US20140158144A1 - Smoking article - Google Patents

Abstract

A smoking article10 comprises a source of smokable material11, a filter12, a first layer13 surrounding at least a part of the filter12, a second layer14 surrounding at least a part of the first layer13 and one or more paths15 for ventilating air flow between the first and second layers13, 14. A part of the first layer13 surrounds the source of smokable material11 and is for attaching the filter12 thereto.

Description

FIELD
• The invention relates to a smoking article and a method of manufacture of a smoking article.
BACKGROUND
• As used herein, the term “smoking article” includes smokable products such as cigarettes, cigars and cigarillos whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not-burn products (i.e. products in which flavour is generated from a smoking material by the application of heat without causing combustion of the material). Typically, smoking articles are provided with filters for removing constituents from the smoke.
• It can be desirable to introduce ventilating air into the smoke. Known ways of doing so involve providing ventilation holes in the outside of the filter. The ventilation holes can be provided relatively straightforwardly but have various disadvantages including, for example, that they are prone to being accidentally blocked by the user's fingers. It is also known to provide grooves in the filter for smoke or ventilating air flow. However, smoking articles including grooved filters can be complex and expensive to manufacture.
SUMMARY
• The invention provides, in a first aspect, a smoking article comprising a source of smokable material, a filter, a first layer surrounding at least a part of the filter, a second layer surrounding at least a part of the first layer and one or more paths for ventilating air flow between the first and second layers, wherein a part of the first layer surrounds the source of smokable material and is for attaching the filter thereto.
• Thus, the invention can provide an effective and efficient way of including paths for ventilating air flow in a smoking article, namely between a first layer, which is also for attaching the filter to the source of smoking material, and a surrounding second layer.
• The invention provides, in a second aspect, a smoking article comprising a source of smokable material, a filter, a first layer surrounding at least a part of the filter, a second layer surrounding at least a part of the first layer and one or more paths for ventilating air flow between the first and second layers, wherein at least a part of the one or more paths is located further from an axis of the smoking article than any part of the filter or of the source of smokable material.
• At least a part of the first layer may comprise an irregular outer surface that defines, together with the second layer, the one or more paths. The one or more paths may have one or more air outlets located near to the end of the filter furthest from the source of smokable material. The one or more paths may have one or more air outlets into the filter. The first layer and/or the second layer may be formed from a sheet material.
• The invention provides, in a third aspect, a method of manufacturing a smoking article, the method comprising providing a source of smokable material, providing a filter, surrounding at least a part of the filter with a first layer, surrounding at least a part of the first layer with a second layer, and forming one or more paths for ventilating air flow between the first and second layers, wherein a part of the first layer surrounds the source of smokable material and is for attaching the filter thereto, or wherein at least a part of the one or more paths is located further from an axis of the smoking article than any part of the filter or of the source of smokable material.
BRIEF DESCRIPTION OF THE DRAWINGS
• Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
• FIG. 1 is a partially-cut-away perspective view of a smoking article according to a first embodiment of the invention;
• FIG. 2 is an end view of the mouth end of the smoking article ofFIG. 1;
• FIG. 3 is a sectional view of the smoking article ofFIG. 1 along the line A-A′ ofFIG. 2;
• FIG. 4 is a plan view of an element used to form the inner covering layer of the smoking article ofFIG. 1;
• FIG. 5 is a partially-cut-away perspective view of a smoking article according to a second embodiment of the invention;
• FIG. 6 is a sectional view of the smoking ofFIG. 5;
• FIG. 7 is a plan view of an element used to form the inner covering layer of the smoking article ofFIG. 5.
DETAILED DESCRIPTIONFirst Embodiment
• FIGS. 1,2 and3 show a smokingarticle10 according to a first embodiment of the invention. The smokingarticle10 includes a source of smokable material, which is preferably tobacco, in the form of atobacco rod11. Thesmoking article10 further includes afilter12 co-axially attached to thetobacco rod11. Aninner covering layer13 is provided around thefilter12 and around a length of thetobacco rod11. Anouter covering layer14 is provided around theinner covering layer13. One ormore channels15 are formed between the inner and theouter covering layers13,14. The one ormore channels15 form one or more paths for the flow of ventilating air from the vicinity of the end of thefilter12 which is nearest to thetobacco rod11 towards the other end of thefilter12. The end of thefilter12 nearest to thetobacco rod11 will be referred to hereinafter as the “tobacco end” of thefilter12. The other end of thefilter12 will be referred to hereinafter as the “mouth end” of thefilter12.
• Thetobacco rod11 and thefilter12 are preferably both cylindrical and preferably both have substantially the same outer diameter. Thefilter12 includes filtration material, preferably surrounded by a sheet material, e.g. plugwrap (not shown). The plugwrap is preferably porous, i.e. permeable to fluid flow, but may be non-porous. The filtration material is preferably cellulose acetate tow, bonded together with a plasticiser. The filtration material is preferably homogeneous. The term “homogenous” is used to mean that the filtration material is substantially uniform throughout thefilter12. Thefilter12 may include an additive such as a smoke modifying agent, e.g. activated charcoal. Thefilter12 is preferably a standard filter but may be any other type of filter, e.g. a composite filter.
• Theinner covering layer13 preferably encircles, at least once, the whole length of thefilter12 and a length of thetobacco rod11 adjacent to thefilter12. Theinner covering layer13 is preferably adhered to and/or secured around thefilter12 and thetobacco rod11, as will be described in more detail below. The inner coveringlayer13 is preferably formed from a sheet material, which is preferably a paper. In some embodiments, the sheet material is made of a non-porous plug wrap which has longer fibre lengths and is more resistant to cracking or splitting when embossed. Alternatively, theinner covering layer13 may be formed from a relatively thick tipping paper or any type of tipping paper or any other suitable material, such as a plastics material, a metal foil or a metallized paper. Theinner covering layer13 is preferably substantially non-porous, i.e. impermeable to fluid flow.
• Theinner covering layer13 preferably forms an elongate cylindrical tube which is longitudinally divided into anirregular portion13aand aregular portion13b. Theportions13aand13bare preferably formed from a single piece of the sheet material.
• Theregular portion13bof theinner covering layer13 preferably encircles, at least once, a length of thefilter12 adjacent to thetobacco rod11 and an adjacent length of thetobacco rod11. Theregular portion13bis preferably adhered, at least in part, to the outer surfaces of the lengths of thefilter12 and thetobacco rod11. Theinner covering layer13 is also preferably secured around the lengths of thefilter12 and thetobacco rod11 by a longitudinal seam of adhesive joining opposite edges. Hence theregular portion13bjoins thefilter12 to thetobacco rod11 and also helps to form a seal against ingress of external air into the tobacco end of thefilter12 during use, i.e. when the user draws on thesmoking article10. Since the inner surface of theregular portion13bof theinner covering layer13 and the outer surfaces of thefilter12 and thetobacco rod11 are all preferably smooth, this can help to provide a good join and a good seal.
• Theirregular portion13aof theinner covering layer13 preferably encircles, at least once, the length of thefilter12 that is not encircled by theregular portion13b. Hence theirregular portion13apreferably extends to the mouth end of thefilter12. However, theirregular portion13aneed not extend to, or may extend beyond, the mouth end of thefilter12. Theirregular portion13ais preferably secured around thefilter12 by a longitudinal seam of adhesive joining opposite edges. Theirregular portion13ais also preferably adhered, at least in part, to the outer surface of thefilter12.
• Theirregular portion13aof theinner covering layer13 is shaped so as to define, in combination with theouter covering layer14, the one ormore channels15.
• Thechannels15 are adapted to deliver ventilating air from near to the tobacco end of thefilter52 to near to the mouth end of thefilter12. The ventilating air is from the atmosphere around thesmoking article10. The ventilating air that is delivered to the mouth end of thefilter12 mixes with, and thus dilutes, the smoke which is drawn through thetobacco rod11 and thefilter12. The mixing takes place outside thesmoking article10, e.g. in the user's mouth. Thechannels15 preferably each have one ormore air inlets16 near to the tobacco end of thefilter12 and one ormore air outlets17 near to the mouth end of thefilter12.
• Theirregular portion13apreferably has a corrugated outer surface, particularly a surface having one or moreelongate grooves18 separated byridges19. Theridges19 are preferably raised in relation to theregular portion13bof theinner covering layer13.
• Thegrooves18 preferably all extend substantially parallel to each other and parallel to the longitudinal axis of thefilter12. However, thegrooves18 may extend in one or more different directions. For example, they may follow one or more helical paths or one or more sinuous paths along thefilter12. Such paths can provide a way of increasing the path length and hence increasing the pressure drop along the path. The pressure drop along the path determines the ventilation properties, as will be described in more detail below.
• Thegrooves18 are preferably equally spaced around the circumference of thefilter12. There are preferably between eight and tengrooves18 spaced around the circumference. However, there may befewer grooves18, e.g. one, two, or fourgrooves18, ormore grooves18, e.g. eighteen or thirty-sixgrooves18. Thegrooves18 are preferably spaced around the whole circumference of thefilter12 but may be spaced around one or more parts of the circumference.
• Theridges19 and thegrooves18 preferably each have a pointed profile so as to form a triangular or sawtooth overall profile. However, the profile of theridges19 and/or thegrooves18 may be different. For example, theridges19 and thegrooves18 may both be curved, thereby forming a sinuous overall profile. Theridges19 may be pointed and thegrooves18 may be curved or vice versa, thereby forming a fluted overall profile. Theridges19 and/or thegrooves18 may include one or more substantially flat portions. For example, they may form a castellated overall profile. Theridges19 and thegrooves18 preferably have a constant profile but may have a profile which varies along the length and/or around the circumference of thefilter12. For example, the width of thegrooves18 may increase or decrease gradually towards the mouth end of thefilter12.
• The width of thegrooves18 and the height of thegrooves18 are preferably selected so as to provide the desired ventilation, as will be described in more detail below.
• Theouter covering layer14 preferably encircles, at least once, the whole length of theinner covering layer13. However, theouter covering layer14 need not extend to, or may extend beyond, one or both ends of theinner covering layer13. Theouter covering layer14 is preferably formed from a sheet material, which is preferably a standard tipping paper. However, theouter covering layer14 may be formed from any suitable material, such as a plastics material, a metal foil or a metallized paper. Theouter covering layer14 is preferably substantially non-porous.
• Theouter covering layer14, in combination with theinner covering layer13, defines the one ormore channels15. Theouter covering layer14 preferably forms a substantially smooth cylindrical tube around theinner covering layer13. In particular, theouter covering layer14 preferably forms a substantially smooth cylindrical tube enveloping the ridges19 (or other protrusions) provided on theirregular portion13aof the inner covering layer. Thus,channels15a₁,15a₂, . . . ,15a_nare formed in the spaces between the inner and the outer covering layers13,14, in thegrooves18 in theirregular portion13aof theinner covering layer13. Anannular space15bis also formed between the inner and the outer covering layers13,14 where theouter covering layer14 extends over theregular portion13bof theinner covering layer13.
• Thechannels15apreferably haverespective outlets17 at their ends nearest to the mouth end of thefilter12. The inner and the outer covering layers13,14 preferably both extend to the end of thefilter12 and so theoutlets17 are preferably located at the end of thefilter12. However, the inner and/or the outer covering layers13,14 may have different extents, as described above, and so theoutlets17 may have different locations. Nevertheless, theoutlets17 are preferably located such that, when the user places thesmoking article10 in the mouth, theoutlets17 will also be in the mouth. Thus, when the user draws on thesmoking article10, ventilating air is drawn through thechannels15a.
• Theannular space15bhas an annular opening at its end away from thechannels15a. This annular opening forms aninlet16 for the ventilating air. Theannular space15bis also in fluid communication with each of thechannels15a. However, theouter covering layer14 need not extend over theregular portion13bof theinner covering layer13 and so there may be no annular space. In this case, thechannels15ahaverespective inlets16 for ventilating air which are located where theouter covering layer14 ends.
• Theouter covering layer14 is preferably secured around theinner covering layer13 by a longitudinal seam of adhesive joining opposite edges. Theouter covering layer14 is also preferably adhered, at least in part, to the ridges19 (or other protrusions) provided on theirregular portion13aof theinner covering layer13.
• Instead of the corrugated outer surface described above, theirregular portion13aof theinner covering layer13 may have any shape which, in combination with theouter covering layer14, forms thechannels15 between the inner and the outer covering layers13,14. For example, theirregular portion13amay include isolated protrusions upon which theouter covering layer14 lies, thereby forming air flow paths in the regions between the protrusions.
• In use, when the user draws on thesmoking article10, smoke and air is drawn through thetobacco rod11 and then thefilter12, and ventilating air is drawn through thechannels15.
• The properties of thechannels15 are preferably selected so as to provide the desired ventilation. In particular, the draw resistance of thechannels15 is determined by, amongst other things, their number, cross-sectional area, length and shape. For example, a larger number ofchannels15 and/orlarger channels15 will have a smaller resistance to the flow of air. This resistance is preferably selected, in relation to the flow resistance through thetobacco rod11 and thefilter12, so as to provide the desired ventilation. For example, if the resistance of thechannels15 is lower in relation to the resistance of thetobacco rod11 and thefilter12, then the amount of air drawn through thechannels15 in relation to the amount of smoke and air drawn through thefilter12 will be higher and so the smoke will be more diluted. Conversely, if the resistance of thechannels15 is higher in relation to the resistance of thetobacco rod11 and thefilter12, then the amount of air drawn through thechannels15 in relation to the amount of smoke and air drawn through thefilter12 will be lower and so the smoke will be less diluted.
• Thesmoking article10 can have the advantage that theinlets16 for ventilating air are less likely to be occluded by the user's fingers. Theinlets16 are preferably positioned near to the tobacco end of thefilter12, or even beyond the tobacco end of thefilter12, and so are away from usual holding position of the user's fingers. Furthermore, theinlets16 are preferably orientated such that they face longitudinally along thesmoking article10 and so, even if the fingers are positioned near to theinlets16, the fingers are still unlikely to occlude theinlets16. In contrast, known smoking article including a plurality of vent holes in the tipping paper can have the disadvantage that the vent holes can be relatively easily occluded by the user's fingers. This can have a negative effect on the consistency of the smoke which is delivered to the user.
• Thesmoking article10 can also have the advantage of providing more effective filtration performance. This is because the ventilating air is mixed with the smoke outside thefilter12. In contrast, known smoking articles in which the ventilating air is introduced into thefilter12 can have the disadvantage that the introduced ventilating air increases the flow rate towards the mouth end of thefilter12, and therefore reduces the residence time of the smoke. This can have a negative effect on the filtering performance.
• Because thefilter12 is preferably completely covered by the inner and the outer covering layers13,14, thesmoking article10 can also have the advantage that a reduced amount of smoke will come into contact with the user's fingers. This is because the inlets are away from usual holding position of the user's fingers. In contrast, in known smoking articles including a plurality of vent holes in the tipping paper, smoke can exit the vent holes and come into contact with the user's fingers, e.g. when the user is not drawing on the smoking article.
• FIG. 4 shows asheet40 for forming theinner covering layer13 of thesmoking article10. The sheet is preferably formed from a standard tipping paper, as described above. The sheet is preferably rectangular and is divided into two rectangular portions, namely anirregular portion40aand aregular portion40b. Theirregular portion40acorresponds to theirregular portion13aof theinner covering layer13. Theregular portion40bcorresponds to theregular portion13bof theinner covering layer13.
• Theirregular portion40ahas a profile as described above in relation to theirregular portion13aof the inner covering layer. The profile preferably has a plurality of raised pointedridges41, as described above. The raised pointedridges41 preferably each have an oblique, triangular side wall42 at their ends nearest to theregular portion40bof thesheet40. However, the sidewall42 may be substantially perpendicular to theregular portion40bof thesheet40 and/or may have a different shape.
• The profile of theirregular portion40aof thesheet40 is preferably formed by embossing. The embossing is preferably carried out using methods which will be known per se to persons skilled in the art. However, the profile may be formed using a method other than embossing. For example, if thesheet40 is formed from a plastics material, then this may be moulded to form the profile. The whole thickness of thesheet40 is preferably formed into the corrugations orirregularities41. Hence the top and bottom surfaces of thesheet40 will both have a similar, irregular profile. This is particularly suitable where thesheet40 is formed from a tipping paper. However, the corrugations orirregularities41 may be formed only towards the top surface of thesheet40, and the bottom surface of the sheet may be substantially smooth. This is particularly suitable where thesheet40 is formed from a relatively thick material.
• Thesmoking article10 can be manufactured using a method in which thetobacco rod11 is joined to thefilter12 by means of theinner covering layer13, which is preferably adhered to and/or secured around thefilter12 and thetobacco rod11, as described above. Thesheet40 for forming theinner covering layer13 is preferably embossed (or otherwise shaped) prior to being wrapped around thefilter12 and thetobacco rod11. Theouter covering layer14 is then preferably wrapped around and adhered to and/or secured around theinner covering layer13.
• Thesmoking article10 can also be manufactured using a method in which twotobacco rods11 are simultaneously joined to each end of a double length of thefilter12 and the resulting article is then cut into two halves to form twosmoking articles10. In this case, a double length of thesheet40 for forming theinner covering layer13 and a double length of a sheet for forming theouter covering layer14 are preferably used. The double length of thesheet40 for forming theinner covering layer13 preferably has theregular portion40bat either end and an intermediate double length of theirregular portion40a.
• A sheet having a symmetrical arrangement of regular and irregular portions is generally preferable since the sheet can be wrapped more effectively, for example without the slewing or creasing that can occur when a sheet having a non-symmetric arrangement is used
• Thesmoking article10 can be manufactured efficiently because its formation preferably largely consists of wrapping layers of sheet material around thefilter12 and thetobacco rod11 and because the wrapping processes themselves can be carried out efficiently. Furthermore, thesmoking article10 can be manufactured using methods and apparatuses which are based upon existing methods and apparatuses. The apparatus may include first and second tipping sections for providing the inner and outer covering layers13,14 respectively.
Second Embodiment
• FIGS. 5 and 6 show asmoking article50 according to a second embodiment of the invention. Thesmoking article50 includes a source of smokable material, which is preferably tobacco, in the form of atobacco rod51. Thesmoking article50 further includes afilter52 co-axially attached to thetobacco rod51. Thefilter52 is longitudinally divided into two filter parts, namely a mouth-end filter part52aand a tobacco-end filter part52b. Aninner covering layer53 is provided around thefilter52 and around a length of thetobacco rod51. Anouter covering layer54 is provided around the inner covering layer. One ormore channels55 are formed between the inner and the outer covering layers53,54. The one ormore channels55 form one or more paths for the flow of ventilating air from near to the tobacco end of the filter to one or more intermediate locations in the filter.
• Thetobacco rod51 and the twofilter parts52a,52bare preferably all cylindrical. Thetobacco rod51 and the tobacco-end filter part52bpreferably have substantially the same outer diameter. The mouth-end filter part52apreferably has a slightly larger outer diameter than the tobacco-end filter part52b, as will be described in more detail below. The twofilter parts52a,52beach include filtration material, preferably surrounded by a sheet material, e.g. plugwrap (not shown). The plugwrap is preferably porous, but may be non-porous. The plugwrap need not be included. The filtration material is preferably cellulose acetate tow, bonded together with a plasticiser. The filtration material is preferably homogeneous. The term “homogenous” is used to mean that the filtration material is substantially uniform throughout thefilter52. The mouth-end and/or tobacco-end filter parts52a,52bmay include an additive such as a smoke modifying agent, e.g. activated charcoal. The twofilter parts52a,52bmay include different filtration materials, may be surrounded by different materials and may include different additives.
• Theinner covering layer53 preferably encircles, at least once, the whole length of the tobacco-end filter part52band an adjacent length of thetobacco rod51. Theinner covering layer53 is preferably adhered to and/or secured around the tobacco-end filter part52band thetobacco rod51, as will be described in more detail below. Theinner covering layer53 is preferably formed from a sheet material, which is preferably a paper. In some embodiments, the sheet material is made of a non-porous plug wrap which has longer fibre lengths and is more resistant to cracking or splitting when embossed. Alternatively, theinner covering layer53 may be formed from a relatively thick tipping paper or any type of tipping paper or any other suitable material, such as a plastics material, a metal foil or a metallized paper. Theinner covering layer53 is preferably substantially non-porous.
• Theinner covering layer53 preferably forms an elongate cylindrical tube which is longitudinally divided into anirregular portion53aand aregular portion53b. Theportions53aand53bare preferably formed from a single piece of the sheet material.
• Theregular portion53bof theinner covering layer53 preferably encircles, at least once, a length of the tobacco-end filter part52badjacent to thetobacco rod51 and an adjacent length of thetobacco rod51. Theregular portion53bis preferably adhered, at least in part, to the outer surfaces of the lengths of the tobacco-end filter part52band thetobacco rod51. Theregular portion53bis also preferably secured around the lengths of the tobacco-end filter part52band thetobacco rod51 by a longitudinal seam of adhesive joining opposite edges. Hence theregular portion53bjoins the tobacco-end filter part52bto thetobacco rod51 and also helps to form a seal against ingress of external air into the tobacco end of thefilter52. Since the inner surface of theregular portion53bof theinner covering layer53 and the outer surfaces of the tobacco-end filter part52band thetobacco rod51 are all preferably smooth, this can help to provide a good join and a good seal.
• Theirregular portion53aof theinner covering layer53 preferably encircles, at least once, the length of the tobacco-end filter part52bthat is not encircled by theregular portion53b. The twofilter parts52a,52bpreferably have a similar length and hence theinner covering layer53 preferably extends to around halfway between the tobacco end and the mouth end of thefilter52. For example, thefilter52 may be 27 mm in length and theirregular portion53amay extend to a distance of 13 mm from the mouth end of thefilter52. However, the mouth-end filter part52a, tobacco-end filter part52band/or theirregular portion53amay have different lengths. Also, the edge of theirregular portion53anearest to the mouth end of thefilter52 may be obliquely angled and/or non-straight and hence the extent of theirregular portion53atowards the mouth end of thefilter52 may vary around the circumference of thefilter52. As will be described below, the extent of theirregular portion53adetermines the extent of thechannels55 and hence the location(s) at which the ventilating air is introduced into thefilter52. Theirregular portion53ais preferably secured around the tobacco-end filter part52bby a longitudinal seam of adhesive joining opposite edges. Theirregular portion53ais also preferably adhered, at least in part, to the outer surface of the tobacco-end filter part52b.
• Theirregular portion53aof theinner covering layer53 is shaped so as to define, in combination with theouter covering layer54, the one ormore channels55.
• Thechannels55 are adapted to deliver ventilating air from near to the tobacco end of thefilter52 to one or more intermediate locations in thefilter52. The one or more intermediate locations are preferable in the vicinity of where thefilter part52a,52bmeet. The ventilating air that is delivered to the intermediate locations enters thefilter52 and mixes with, and thus dilutes, the smoke which is drawn through thetobacco rod51 and thefilter52. The mixing takes place mainly in thefilter52. Thechannels55 preferably each have one ormore air inlets56 near to the tobacco end of thefilter52 and one ormore air outlets57 at the intermediate locations in thefilter52.
• Theirregular portion53apreferably has a corrugated outer surface, particularly a surface having one or moreelongate grooves58 separated byridges59. Theridges59 are preferably raised in relation to theregular portion53bof theinner covering layer53.
• Thegrooves58 preferably all extend substantially parallel to each other and parallel to the longitudinal axis of thefilter52. However, thegrooves58 may extend in one or more different directions. For example, they may follow one or more helical paths or one or more sinuous paths along thefilter52. Such paths can provide a way of increasing the path length and hence increasing the pressure drop along the path.
• Thegrooves58 are preferably equally spaced around the circumference of thefilter12. There are preferably between eight and tengrooves58 spaced around the circumference. However, there may befewer grooves58, e.g. one, two, or fourgrooves58, ormore grooves58, e.g. eighteen or thirty-sixgrooves58. Thegrooves58 are preferably spaced around the whole circumference of thefilter52 but may be spaced around one or more parts of the circumference.
• Theridges59 and thegrooves58 preferably each have a pointed profile so as to form a triangular or sawtooth overall profile. However, the profile of theridges59 and/or thegrooves58 may be different. For example, theridges59 and thegrooves58 may both be curved, thereby forming a sinuous overall profile. Theridges59 may be pointed and thegrooves58 may be curved or vice versa, thereby forming a fluted overall profile. Theridges59 and/or thegrooves58 may include one or more substantially flat portions. For example, they may form a castellated overall profile. Theridges59 and thegrooves58 preferably have a constant profile but may have a profile which varies along the length and/or around the circumference of thefilter52. For example, the width of thegrooves58 may increase or decrease gradually towards one end.
• The width of thegrooves58 and the height of thegrooves58 are preferably selected so as to provide the desired ventilation, as will be described in more detail below.
• Theouter covering layer54 preferably encircles, at least once, the whole length of theinner covering layer53 and the whole length of the mouth-end filter part52. Hence theouter covering layer54 preferably extends to the mouth end of thefilter52. However, theouter covering layer54 may extend further or less than this. Theouter covering layer54 is preferably formed from a sheet material, which is preferably a tipping paper. However, theouter covering layer54 may be formed from any suitable material, such as a plastics material, a metal foil or a metallized paper. Theouter covering layer54 is preferably substantially non-porous.
• Theouter covering layer54, in combination with theinner covering layer53, defines the one ormore channels55. Theouter covering layer54 preferably forms a substantially smooth cylindrical tube around theinner covering layer53 and the length of thefilter52 not encircled by theinner covering layer53. In particular, theouter covering layer54 preferably forms a substantially smooth cylindrical tube enveloping the ridges59 (or other protrusions) in theirregular portion53aof the inner covering layer. Thus,channels55a₁,55a₂, . . . ,55a_nare formed in the spaces between the inner and the outer covering layers53,54, in thegrooves58 in theirregular portion53aof the inner covering layer. Anannular space55bis also formed between the inner and the outer covering layers53,54 where theouter covering layer54 extends over theregular portion53bof theinner covering layer53. Theouter covering layer54 also fits closely around the mouth-end filter part52a. The outer diameter of the mouth-end filter part52ais preferably substantially the same as the diameter of the cylinder that envelopes theirregular portion53aof theinner covering layer53. Thus, theouter covering layer54 extends smoothly between theirregular portion53aof theinner covering layer53 and the mouth-end filter part52a.
• The extent of thechannels55atowards the mouth end of thefilter52 is preferably determined by the extent of theirregular portion53aof theinner covering layer53, as described above. Theirregular portion53aand hence thechannels55apreferably end at one or more intermediate locations in thefilter52, preferably in the vicinity of where the twofilter parts52a,52bmeet. Thechannels55apreferably haverespective outlets57 at their ends at the intermediate locations. Because theouter covering layer54 fits closely around the length of thefilter52 not encircled by theinner covering layer53, ventilating air exiting theoutlets57 is directed into the interior of thefilter52 and, in particular, into the interior of the mouth-end filter part52a.
• Theannular space55bhas an annular opening at its end towards the tobacco end of thefilter52. This annular opening forms aninlet56 for the ventilating air. Theannular space55bis also in fluid communication with each of thechannels55a. However, theouter covering layer54 need not extend over theregular portion53bof theinner covering layer53 and so there may be no annular space. In this case, thechannels55ahaverespective inlets56 for ventilating air which are located where theouter covering layer54 ends.
• Theouter covering layer54 is preferably secured around theinner covering layer53 by a longitudinal seam of adhesive joining opposite edges. Theouter covering layer54 is also preferably adhered, at least in part, to the ridges59 (or other protrusions) provided on theirregular portion53aof theinner covering layer53.
• Instead of the corrugated outer surface described above, theirregular portion53aof theinner covering layer53 may have any shape which, in combination with theouter covering layer54, forms the channel between the inner and the outer covering layers53,54. For example, theirregular portion53amay include isolated protrusions upon which theouter covering layer54 lies, thereby forming air flow paths in the regions between the protrusions.
• In use, when the user draws on thesmoking article50, smoke and air is drawn through thetobacco rod51 and then thefilter52, and ventilating air is drawn through thechannels55 and then a length of thefilter52.
• The properties of thechannels55 are preferably selected so as to provide the desired ventilation. In particular, the draw resistance of thechannels55 is determined by, amongst other things, their number, cross-sectional area, length and shape. This resistance and hence the pressure drop is preferably chosen to provide the desired ventilation. The locations of theoutlets57 of thechannels55a, i.e., the distance from either end of thefilter52, can also be selected to provide desired characteristics for thefilter52, e.g. filtering and dilution characteristics.
• Thesmoking article50 can have the advantage that theinlets56 for ventilating air are much less likely to be occluded by the user's fingers as described above in relation to the first embodiment.
• FIG. 7 shows asheet70 for forming theinner covering layer53 of thesmoking article50. Thesheet70 is preferably formed from a standard tipping paper, as described above. Thesheet70 is preferably rectangular and is divided into two rectangular portions, namely anirregular portion70aand aregular portion70b. Theirregular portion70acorresponds to theirregular portion53aof theinner covering layer53. Theregular portion70bcorresponds to theregular portion53bof theinner covering layer53.
• Theirregular portion70ahas a profile as described above in relation to theirregular portion53aof the inner covering layer. The profile preferably has a plurality of raised pointedridges71, as described above. The raised pointedridges71 preferably each have an oblique, triangular side wall72 at their ends nearest to theregular portion70bof thesheet70. However, the sidewall72 may be substantially perpendicular to theregular portion70bof thesheet70 and/or may have a different shape.
• The profile of theirregular portion70aof the sheet is preferably formed by embossing. The embossing is preferably carried out using methods which will be known per se to persons skilled in the art. However, the profile may be formed using a method other than embossing. For example, if thesheet70 is formed from a plastics material, then this may be moulded to form the profile. The whole thickness of thesheet70 is preferably formed into the corrugations orirregularities71. Hence the top and bottom surfaces of thesheet70 will both have a similar, irregular profile. This is particularly suitable where thesheet70 is formed from a tipping paper. However, the corrugations or irregularities may be formed only towards the top surface of thesheet70, and the bottom surface of thesheet70 may be substantially smooth. This is particularly suitable where thesheet70 is formed from a relatively thick material.
• Thesmoking article50 can be manufactured using a method in which thetobacco rod51 is joined to the tobacco-end filter part52bby means of theinner covering layer53, which is preferably adhered to and/or secured around the tobacco-end filter part52band thetobacco rod51, as described above. Thesheet70 for forming theinner covering layer53 is preferably embossed (or otherwise shaped) prior to being wrapped around thefilter52 and thetobacco rod51. The mouth-end filter part52ais then joined to the tobacco-end filter part52bandtobacco rod51 by means of theouter covering layer54, which is preferably wrapped around and adhered to and/or secured around the tobacco-end filter part52aand theinner covering layer53.
• Thesmoking article50 can be manufactured using a method in which twotobacco rods51 are simultaneously joined to each end of a double length of the tobacco-end filter part52b. A double length of thesheet70 for forming theinner covering layer53 is preferably used. The sheet preferably has theregular portion70bat either end and an intermediate double length of theirregular portion70a. The resulting article is then cut into two halves. The tobacco-end filter part52 may be joined to each half as described above. Alternatively, the two halves may be simultaneously joined to each end of a double length of the tobacco-end filter part52a. A double length of a sheet for forming theouter covering layer54 is preferably used. The resulting article is then cut into two halves to form twosmoking articles50.
• Thesmoking article50 can be manufactured efficiently because its formation preferably largely consists of wrapping layers of sheet material around the twofilter parts52a,52band thetobacco rod51 and because the wrapping processes themselves can be carried out efficiently. Furthermore, thesmoking article50 can be manufactured using methods and apparatuses which are based upon existing methods and apparatuses. The apparatus may include first and second tipping sections for providing the inner and outer covering layers53,54 respectively. The twofilter parts52a,52band the separate wrapping thereof can allow thesheet70 for forming theinner covering layer53 to be positioned more easily and can also enable a double length of thesheet70 to be used in the ‘two-up’ manufacturing method described above.
Further Embodiments
• It should be realised that the hereinbefore described example embodiments should not be construed as limiting. Other variations and modifications will be apparent to persons skilled in the art upon reading the present application.
• Theregular portion13b,53bof theinner covering layer13,53 may only encircle a length of thetobacco rod11,51, rather than lengths of thefilter12,52 and thetobacco rod11,51. Theregular portion13b,53bis preferably adhered to and secured around the length of thetobacco rod11,51. This can still help to form a good seal against air ingress between theinner covering layer13,53 and thetobacco rod11,51. In this case, theirregular portion13a,53aof theinner covering layer13,53 is preferably adhered to thefilter12,52 to join thefilter12,52 to thetobacco rod11,51.
• Theinner covering layer13,53 need not include theregular portion13b,53band so may consist of only theirregular portion13a,53a. In this case, theirregular portion13a,53apreferably joins together, and forms a seal between, thefilter12,52 and thetobacco rod11,51. If the inner surface of theirregular portion13a,53ais smooth, then a good seal can be achieved by adhering and/or securing as described above in relation to theregular portion13b,53b. If the inner surface of theirregular portion13a,53ais not smooth, e.g. because theinner covering layer13,53 is formed from an embossed tipping paper, then further modifications may be needed to help to achieve a good seal. For example, a relatively thick layer of adhesive may be provided between theinner covering layer13,53 and thetobacco rod11,51 for bridging the spaces therebetween.
• Instead of the smooth cylindrical shape described above, thefilter12,52 may have a different shape.
• For example, the outer surface of thefilter12,52 may be provided with corrugations or irregularities to complement those provided on the inner surface of theirregular portion13a,53aof theinner covering layer13,53. Hence thefilter12,52 substantially fills the volume inside theinner covering layer13,53. This can help to avoid there being any smoke paths through thesmoking article10,50 which do not pass through the filtration material.
• Furthermore, in relation to the second embodiment only, thefilter52 may not be divided into the twofilter parts52a,52b. In this case, thefilter52 preferably has a length with an increased diameter at its mouth end. The length preferably starts where theirregular portion53aofinner covering layer53 ends. The increased diameter is preferably substantially the same as the diameter of the cylinder that envelopes theirregular portion53aof theinner covering layer53. However, thefilter52 may have a uniform outer diameter instead. In this case, theouter covering layer54 may be provided with a length with an increased thickness at its mouth end. Thus, theouter covering layer54 can be wrapped around theinner covering layer53 and thefilter52 with less mechanical stress in thefilter52 and thelayers53,54.
• Instead of being substantially non-porous, the inner and/or the outer covering layers13,14,53,54 may be porous. For example, they may be formed of a porous material and/or they may be provided with ventilation holes. Thus, in addition to the flow along the whole length of thechannels15,55, ventilating air may also be able to enter thechannels15,55 though theouter covering layer14,54 and/or exit the channels through theinner covering layer13,53 into thefilter12,52. The porosity of the inner and/or the outer covering layers13,14,53,54 can be selected to provide asmoking article10,50 having desired ventilation characteristics.
• Theinner covering layer13,53 need not encircle thetobacco rod11,51 and need not be for joining thefilter12,52 to thetobacco rod11,51. Instead, a further covering layer may be used to join thefilter12,52 to thetobacco rod11,51. For example, a further covering layer may be adhered to and/or secured around a length of theregular portion13b,53bofinner wrapping layer13,53 and a length of thetobacco rod11,51. Thus, in this case, thefilter12,52 may be wrapped with the inner and the outer covering layers13,14,53,54 independently of the formation of thesmoking article10,50.
• Instead of being a substantially smooth cylindrical tube, theouter covering layer14,54 may have a different shape.
• For example, theouter covering layer14,54 may be provided with corrugations or other irregularities on its inner surface. These corrugations or irregularities may be provided instead of those in theinner covering layer13,53 so as to define thechannels15,55. In this case, theinner covering layer13,53 need not be provided with anirregular portion13a,53a. Alternatively, the corrugations or irregularities in theouter covering layer14,54 may be adapted to co-operate with those in theinner covering layer13,53 so as to define thechannels15,55. For example, the inner and the outer covering layers13,14,53,54 may have a plurality of aligned grooves and ridges.
• Furthermore, theouter covering layer14,54 may be provided with corrugations or other irregularities on its inner surface in the region where it encircles theregular portion13a,53aof theinner covering layer13,53. This can help to maintain the space between the inner and the outer covering layers13,14,53,54 in this region and so ensure that the flow of ventilating air into thechannels15a,55ais less likely to be blocked, e.g. by deformation of theouter covering layer14,54 during use.
• Embodiments of the invention are configured to comply with applicable laws and/or regulations, such as, by way of non-limiting example, regulations relating to flavours, additives, emissions, constituents, and/or the like.
• Any of the features described in any embodiment may be used in combination with any other features of any other embodiment.

Claims (23)

1. A smoking article comprising a source of smokable material, a filter, a first layer surrounding at least a part of the filter, a second layer surrounding at least a part of the first layer, and at least one path for ventilating air flow between the first and second layers, wherein a part of the first layer surrounds the source of smokable material and attaches the filter thereto.

2. A smoking article comprising a source of smokable material, a filter, a first layer surrounding at least a part of the filter, a second layer surrounding at least a part of the first layer, and at least one path for ventilating air flow between the first and second layers, wherein at least a part of the at least one path is located further from an axis of the smoking article than any part of the filter or of the source of smokable material.

3. The smoking article according toclaim 1, wherein at least a part of the first layer comprises an irregular outer surface that defines, together with the second layer, the at least one path.

4. The smoking article according toclaim 3, wherein the irregular outer surface comprises a plurality of elongate ridges extending generally along the filter, the at least one path being at least partially located between adjacent ridges.

5. The smoking article according toclaim 1, wherein the first layer comprises a part with a smooth inner surface that surrounds a part of the source of smokable material or surrounds adjacent parts of the source of smokable material and of the filter.

6. The smoking article according toclaim 1, wherein the at least one path has at least one air inlet that is located one of near to and beyond an end of the filter nearest to the source of smokable material, the at least one air inlet defined by extents of the first and the second layers one of towards and beyond the end of the filter.

7. The smoking article according toclaim 1, wherein the at least one path has at least one air outlet located near to an end of the filter furthest from the source of smokable material, the at least one air outlet defined by extents of the first and the second layers one of towards and beyond the end of the filter.

8. The smoking article according toclaim 1, wherein the at least one path has at least one air outlet into the filter, the at least one air outlet into the filter defined by an extent of the first covering layer towards an end of the filter furthest from the source of smokable material, and wherein the second layer extends one of to and near to the end of the filter.

9. The smoking article according toclaim 8, wherein the filter is longitudinally divided into first and second filter parts, the first layer extending one of to and near to the end of the first filter part furthest from the source of smokable material, and wherein the second layer extends one of to and near to the end of the second filter part furthest from the source of smokable material.

10. The smoking article according toclaim 1, wherein at least one of the first layer and the second layer is formed from a sheet material.

11. A method of manufacturing a smoking article, the method comprising providing a source of smokable material, providing a filter, surrounding at least a part of the filter with a first layer, surrounding at least a part of the first layer with a second layer, and forming at least one path for ventilating air flow between the first and second layers, wherein a part of the first layer surrounds the source of smokable material and is configured to attach the filter thereto, or wherein at least a part of the one or more paths is located further from an axis of the smoking article than any part of the filter or of the source of smokable material.

12. The method according toclaim 11, further comprising forming an irregular outer surface on at least a part of the first layer, the irregular outer surface defining, together with the second layer, the at least one path.

13. The method according toclaim 12, wherein the first layer is formed from a sheet material, and wherein forming the irregular outer surface comprises embossing the sheet material.

14. The method according toclaim 11, comprising providing a first filter part, surrounding at least a part of the first filter part with the first layer, providing a second filter part adjacent to the first filter part, and surrounding at least a part of the first layer and at least a part of the second filter part with the second layer.

15. (canceled)

16. The smoking article according toclaim 2, wherein at least a part of the first layer comprises an irregular outer surface that defines, together with the second layer, the at least one path.

17. The smoking article according toclaim 16, wherein the irregular outer surface comprises a plurality of elongate ridges extending generally along the filter, the at least one path being at least partially located between adjacent ridges.

18. The smoking article according toclaim 2, wherein the first layer comprises a part with a smooth inner surface that surrounds a part of the source of smokable material or surrounds adjacent parts of the source of smokable material and of the filter.

19. The smoking article according toclaim 2, wherein the at least one path has at least one air inlet that is located one of near to and beyond an end of the filter nearest to the source of smokable material, the at least one air inlet defined by extents of the first and the second layers one of towards and beyond the end of the filter.

20. The smoking article according toclaim 2, wherein the at least one path has at least one air outlet located near to an end of the filter furthest from the source of smokable material, the at least one air outlet defined by extents of the first and the second layers one of towards and beyond the end of the filter.

21. The smoking article according toclaim 2, wherein the at least one path has at least one air outlet into the filter, the at least one air outlet into the filter defined by an extent of the first covering layer towards an end of the filter furthest from the source of smokable material, and wherein the second layer extends one of to and near to the end of the filter.

22. The smoking article according toclaim 21, wherein the filter is longitudinally divided into first and second filter parts, the first layer extending one of to and near to the end of the first filter part furthest from the source of smokable material, and wherein the second layer extends one of to and near to the end of the second filter part furthest from the source of smokable material.

23. The smoking article according toclaim 2, wherein at least one of the first layer and the second layer is formed from a sheet material.

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