Smoking article with non-overlapping, radially separated, dual heat-conducting elements

Abstract

A smoking article is provided, including a combustible heat source having opposed front and rear faces; an aerosol-forming substrate downstream of the rear face of the heat source; a first heat-conducting element including one or more radially inner layers of heat-conductive material overlying a rear portion of the combustible heat source; and a second heat-conducting element including one or more radially outer layers of heat-conductive material overlying at least a portion of the aerosol-forming substrate, such that the one or more radially outer layers of heat-conductive material do not overlie the one or more radially inner layers of heat-conductive material.

Claims

1. A smoking article, comprising: a combustible heat source having opposed front and rear faces; an aerosol-forming substrate downstream of the rear face of the combustible heat source; a first heat-conducting element comprising one or more radially inner layers of heat-conductive material overlying a rear portion of the combustible heat source; and a second heat-conducting element comprising one or more radially outer layers of heat-conductive material overlying at least a portion of the aerosol-forming substrate, wherein a radial distance between a longitudinal axis of the smoking article and the one or more radially outer layers of heat-conductive material is greater than a radial distance between the longitudinal axis of the smoking article and the one or more radially inner lavers of heat-conductive material, and wherein the one or more radially outer layers of heat-conductive material do not overlie the one or more radially inner layers of heat-conductive material.

2. The smoking article according to claim 1, wherein the one or more radially inner layers of heat-conductive material overlying the rear portion of the combustible heat source also overlie a front portion of the aerosol-forming substrate, and wherein the one or more radially outer layers of heat-conductive material also overlie a rear portion of the aerosol-forming substrate.

3. The smoking article according to claim 1, wherein the one or more radially outer layers of heat-conductive material overlie an entire length of the aerosol-forming substrate.

4. The smoking article according to claim 1, wherein the one or more radially outer layers of heat-conductive material of the second heat-conducting element are longitudinally spaced apart from the one or more radially inner layers of heat-conductive material of the first heat-conducting element.

5. The smoking article according to claim 1, wherein the second heat-conducting element is formed of a laminate material comprising one or more layers of heat-conductive-material and one or more layers of heat-insulative material.

6. The smoking article according to claim 1, wherein the second heat-conducting element comprises one or more layers of heat-reflective material.

7. The smoking article according to claim 6, wherein the heat-reflective material reflects more than 50% of incident radiation.

8. The smoking article according to claim 1, wherein the first heat-conducting element and the second heat-conducting element are radially separated by one or more layers of heat-insulative material.

9. The smoking article according to claim 1, further comprising an outer wrapper around at least a portion of the second heat-conducting element.

10. The smoking article according to claim 1, wherein a radially outer layer of heat-conductive material of the one or more radially outer layers is provided on an outside of the smoking article, such that the radially outer layer of heat-conductive material is visible on an exterior of the smoking article.

11. The smoking article according to claim 1, further comprising a non-combustible substantially air impermeable barrier between the rear face of the combustible heat source and the aerosol-forming substrate.

12. The smoking article according to claim 1, wherein the combustible heat source is a blind combustible heat source.

13. The smoking article according to claim 1, further comprising one or more airflow channels extending from the front face to the rear face of the combustible heat source.

14. The smoking article according to claim 13, further comprising a non-combustible substantially air impermeable barrier between the combustible heat source and the one or more airflow channels.

15. The smoking article according to claim 1, further comprising one or more air inlets around a periphery of the aerosol-forming substrate.

16. The smoking article according to claim 1, wherein the aerosol-forming substrate is spaced apart from the rear face of the combustible heat source.

17. The smoking article according to claim 16, further comprising one or more air inlets between the rear face of the combustible heat source and the aerosol-forming substrate.

18. The smoking article according to claim 1, further comprising one or more air inlets downstream of the aerosol-forming substrate.

19. The smoking article according to claim 1, further comprising one or more aerosol modifying agents downstream of the aerosol-forming substrate.

Description

(1) The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1 shows a schematic longitudinal cross-section of a smoking article according to a first embodiment of the invention;

(3) FIG. 2 shows a schematic longitudinal cross-section of a smoking article according to a third embodiment of the invention; and

(4) FIG. 3 shows a schematic longitudinal cross-section of a smoking article according to a fifth embodiment of the invention.

(5) The smoking article 2 according to the first embodiment of the invention shown in FIG. 1 comprises a blind combustible heat source 4 having a front face 6 and an opposed rear face 8, an aerosol-forming substrate 10, a transfer element 12, an aerosol-cooling element 14, a spacer element 16 and a mouthpiece 18 in abutting coaxial alignment.

(6) The blind combustible heat source 4 is a blind carbonaceous combustible heat source and is located at the distal end of the smoking article 2. As shown in FIG. 1, a non-combustible substantially air impermeable barrier 22 in the form of a disc of aluminium foil is provided between the rear face 8 of the blind combustible heat source 4 and the aerosol-forming substrate 10. The barrier 22 is applied to the rear face 8 of the blind combustible heat source 4 by pressing the disc of aluminium foil onto the rear face 8 of the blind combustible heat source 4 and abuts the rear face 8 of the combustible carbonaceous heat source 4 and the aerosol-forming substrate 10. It will be appreciated that in other embodiments of the invention (not shown), the non-combustible substantially air impermeable barrier 22 between the rear face 8 of the blind combustible heat source 4 and the aerosol-forming substrate 10 may be omitted.

(7) The aerosol-forming substrate 10 is located immediately downstream of the first barrier 22 applied to the rear face 8 of the blind combustible heat source 4. The aerosol-forming substrate 10 comprises a cylindrical plug of homogenised tobacco-based material 24 including an aerosol former such as, for example, glycerine, wrapped in plug wrap 26.

(8) The transfer element 12 is located immediately downstream of the aerosol-forming substrate 10 and comprises a cylindrical open-ended hollow cellulose acetate tube 28.

(9) The aerosol-cooling element 14 is located immediately downstream of the transfer element 12 and comprises a gathered sheet of biodegradable polymeric material such as, for example, polylactic acid.

(10) The spacer element 16 is located immediately downstream of the aerosol-cooling element 14 and comprises a cylindrical open-ended hollow paper or cardboard tube 30.

(11) The mouthpiece 18 is located immediately downstream of the spacer element 16. As shown in FIG. 1, the mouthpiece 18 is located at the proximal end of the smoking article 2 and comprises a cylindrical plug of suitable filtration material 32 such as, for example, cellulose acetate tow of very low filtration efficiency, wrapped in filter plug wrap 34.

(12) The smoking article 2 comprises a first heat-conducting element 36 comprising a radially inner layer of heat-conductive material such as, for example, aluminium foil, overlying and in direct contact with a rear portion of the blind combustible heat source 4 and a front portion of the aerosol-forming substrate 10. The smoking article 2 also comprises a second heat-conducting element 38 comprising a radially outer layer of heat-conductive material such as, for example, aluminium foil, overlying a rear portion of the aerosol-forming substrate 10 and the entire length of the transfer element 12. As shown in FIG. 1, the radially outer layer of heat-conductive material of the second heat-conducting element 38 does not overlie the radially inner layer of heat-conductive material of the first heat-conducting element 36.

(13) In other embodiments of the invention (not shown), the first heat-conducting element 36 may comprise one or more radially inner layers of heat-conductive material that overlie a rear portion of the blind combustible heat source 4 and the second heat-conducting element 38 may comprise one or more radially outer layers of heat-conductive material that overlie the entire length of the aerosol-forming substrate 10.

(14) Alternatively or in addition, in other embodiments of the invention (not shown), the transfer element 12 may extend beyond the one or more radially outer layers of heat-conductive material of the second heat-conducting element 38 in the downstream direction. In such embodiments, the one or more radially outer layers of heat-conductive material of the second heat-conducting element 38 may overlie only a front portion of the transfer element 12. Alternatively, in such embodiments, the one or more radially outer layers of heat-conductive material of the second heat-conducting element 38 may not overlie any of the transfer element 12.

(15) In the first embodiment of the invention shown in FIG. 1, the position around the aerosol-forming substrate 10 to which the radially inner layer of heat-conductive material of the first heat-conducting element 36 extends in the downstream direction is approximately the same as the position around the aerosol-forming substrate 10 to which the radially outer layer of heat-conductive material of the second heat-conducting element 38 extends in the upstream direction. That is, the downstream end of the radially inner layer of heat-conductive material of the first heat-conducting element 36 and the upstream end of the radially outer layer of heat-conductive material of the second heat-conducting element 38 are substantially aligned over the aerosol-forming substrate 10. In other embodiments of the invention (not shown), the one or more radially outer layers of heat-conductive material of the second heat-conducting element 38 may be longitudinally spaced apart from the one or more radially inner layers of heat-conductive material of the first heat-conducting element 36.

(16) The first heat-conducting element 36 and the second heat-conducting element 38 are radially separated by a layer of heat-insulative material 40 such as, for example, cigarette paper, that overlies the entire length of the radially inner layer of heat-conductive material of the first heat-conducting element 36 and underlies the entire length of the radially outer layer of heat-conductive material of the second heat-conducting element 38.

(17) As shown in FIG. 1, the layer of heat-insulative material 40 circumscribes the radially inner layer of heat-conductive material of the first heat-conducting element 36, the aerosol-forming substrate 10, the transfer element 12, the aerosol-cooling element 14, the spacer element 16 and the mouthpiece 18.

(18) The smoking article may further comprise a band of tipping paper (not shown) circumscribing a downstream end portion of the layer of heat-insulative material 40.

(19) The smoking article 2 according to the first embodiment of the invention comprises one or more first air inlets 42 around the periphery of the aerosol-forming substrate 10. As shown in FIG. 1, a circumferential arrangement of first air inlets 42 is provided in the plug wrap 26 of the aerosol-forming substrate 10 and the radially outer layer of heat-conductive material of the second heat conducting element 38 to admit cool air (shown by dotted arrows in FIG. 1) into the aerosol-forming substrate 10.

(20) In use, a user ignites the blind combustible heat source 4 of the smoking article 2 according to the first embodiment of the invention and then draws on the mouthpiece 18. When a user draws on the mouthpiece 18, cool air (shown by dotted arrows in FIGS. 1) is drawn into the aerosol-forming substrate 10 of the smoking article 2 through the first air inlets 42.

(21) The front portion of the aerosol-forming substrate 10 is heated by conduction through the rear face 8 of the blind combustible heat source 4 and the barrier 22 and the first heat-conducting element 36. The heating of the aerosol-forming substrate 10 by conduction releases glycerine and other volatile and semi-volatile compounds from the plug of homogenised tobacco-based material 24. The compounds released from the aerosol-forming substrate 10 form an aerosol that is entrained in the air drawn into the aerosol-forming substrate 10 of the smoking article 2 through the first air inlets 42 as it flows through the aerosol-forming substrate 10. The drawn air and entrained aerosol (shown by dashed arrows in FIG. 1 pass downstream through the interior of the cylindrical open-ended hollow cellulose acetate tube 28 of the transfer element 12, the aerosol-cooling element 14 and the spacer element 16, where they cool and condense. The cooled drawn air and entrained aerosol pass downstream through the mouthpiece 18 and are delivered to the user through the proximal end of the smoking article 2 according to the first embodiment of the invention. The non-combustible substantially air impermeable barrier 22 on the rear face 8 of the blind combustible heat source 4 isolates the blind combustible heat source 4 from air drawn through the smoking article 2 such that, in use, air drawn through the smoking article 2 does not come into direct contact with the blind combustible heat source 4.

(22) In use, the second heat-conducting element 38 reduces radiative heat losses from the outer surfaces of the smoking article 2. This in turn helps maintain the temperature of the aerosol-forming substrate 10 to facilitate continued and enhanced aerosol delivery.

(23) It will be appreciated that in other embodiments of the invention (not shown), the smoking article may further comprise an outer wrapper of sheet material such as, for example, cigarette paper, of low air permeability, which circumscribes the aerosol-forming substrate 10, the transfer element 12, the aerosol-cooling element 14, the spacer element 16, the mouthpiece 18 and a rear portion of the blind combustible heat source 4 and which overlies the second heat-conducting element.

(24) In such embodiments, the circumferential arrangement of first air inlets 42 is provided in the plug wrap 26 of the aerosol-forming substrate 10, the radially outer layer of heat-conductive material of the second heat conducting element 38, and the overlying outer wrapper to admit cool air (shown by dotted arrows in FIG. 1) into the aerosol-forming substrate 10.

(25) A smoking article according to a second embodiment of the invention (not shown) is of largely identical construction to the smoking article according to the first embodiment of the invention shown in FIG. 1. However, in the smoking article according to the second embodiment of the invention, the layer of heat-insulative material 40 overlying the first heat-conducting element 36 and underlying the second heat-conducting element 38 is omitted and the second heat-conducting element 38 is formed of a laminate material comprising an outer layer of heat-conductive material such as, for example, aluminium, and an inner layer of heat-insulative material such as, for example, paper.

(26) The smoking article 44 according to the third embodiment of the invention shown in FIG. 2 is of largely identical construction to the smoking article according to the first embodiment of the invention shown in FIG. 1. However, in the smoking article 44 according to the third embodiment of the invention, the first air inlets 42 around the periphery of the aerosol-forming substrate 10 are omitted and the combustible heat source 4 is a non-blind combustible carbonaceous heat source comprising a single central airflow channel 46 extending from the front face 6 to the rear face 8 of the non-blind combustible heat source 4.

(27) As shown in FIG. 2, a non-combustible substantially air impermeable barrier 48 is provided between the combustible heat source 4 and the central airflow channel 46. The barrier 48 comprises a non-combustible substantially air impermeable barrier coating provided on the entire inner surface of the single central airflow channel 46. In other embodiments of the invention (not shown), the non-combustible substantially air impermeable barrier 48 between the combustible heat source 4 and the central airflow channel 46 may be omitted.

(28) Like the smoking article according to the first embodiment of the invention shown in FIG. 1, the smoking article 44 according to the third embodiment of the invention shown in FIG. 2 comprises a first heat-conducting element 36 comprising a radially inner layer of heat-conductive material overlying and in direct contact with a rear portion of the blind combustible heat source 4 and a front portion of the aerosol-forming substrate 10 and a second heat-conducting element 38 comprising a radially outer layer of heat-conductive material overlying the a rear portion of the aerosol-forming substrate 10 and the entire length of the transfer element 12. However, as shown in FIG. 1, in the smoking article 44 according to the second embodiment of the invention, the radially outer layer of heat-conductive material of the second heat-conducting element 38 is longitudinally spaced apart from the radially inner layer of heat-conductive material of the first heat-conducting element 36.

(29) In use, a user ignites the non-blind combustible heat source 4 of the smoking article 44 according to the second embodiment of the invention and then draws on the mouthpiece 18. When a user draws on the mouthpiece 18, cool air (shown by dotted arrows in FIG. 2) is drawn into the aerosol-forming substrate 10 of the smoking article 2 through the central airflow channel 46. The non-combustible substantially air impermeable barrier 22 on the rear face 8 of the non-blind combustible heat source 4 and the non-combustible substantially air impermeable barrier 48 on the inner surface of the single central airflow channel 46 isolate the non-blind combustible heat source 4 from air drawn through the smoking article 44 such that, in use, air drawn through the smoking article 44 does not come into direct contact with the non-blind combustible heat source 4.

(30) A smoking article according to a fourth embodiment of the invention (not shown) is of largely identical construction to the smoking article according to the third embodiment of the invention shown in FIG. 2. However, in the smoking article according to the third embodiment of the invention, the layer of heat-insulative material 40 overlying the first heat-conducting element 36 and underlying the second heat-conducting element 38 is omitted and the second heat-conducting element 38 is formed of a laminate material comprising an outer layer of heat-conductive material such as, for example, aluminium, and an inner layer of heat-insulative material such as, for example, paper.

(31) The smoking article 50 according to the fifth embodiment of the invention shown in FIG. 3 is of largely identical construction to the smoking article according to the first embodiment of the invention shown in FIG. 1. However, in the smoking article 50 according to the fifth embodiment of the invention, the first air inlets 42 around the periphery of the aerosol-forming substrate 10 and the transfer element 12 are omitted, being replaced by third air inlets 52 and an airflow directing element 54 respectively.

(32) The airflow directing element 54 is located downstream of the aerosol-forming substrate 10 and comprises an open-ended, substantially air impermeable hollow tube 56 made of, for example, cardboard, which is of reduced diameter compared to the aerosol-forming substrate 10. The upstream end of the open-ended hollow tube 56 abuts the aerosol-forming substrate 10. The downstream end of the open-ended hollow tube 56 is surrounded by an annular substantially air impermeable seal 58 of substantially the same diameter as the aerosol-forming substrate 10. The remainder of the open-ended hollow tube is embedded in a cylindrical plug of cellulose acetate tow 60 of substantially the same diameter as the aerosol-forming substrate 10.

(33) The open-ended hollow tube 56 and cylindrical plug of cellulose acetate tow 60 are circumscribed by an air permeable inner wrapper 62.

(34) As also shown in FIG. 3, a circumferential row of the third air inlets 52 are provided in the layer of heat-insulative material 40 circumscribing the inner wrapper 62.

(35) In use, when a user draws on the mouthpiece 10, cool air is drawn into the smoking article 50 according to the second embodiment of the invention through the third air inlets 52. The drawn air passes upstream between the exterior of the open-ended hollow tube 56 and the inner wrapper 62 through the cylindrical plug of cellulose acetate tow 60 to the aerosol-forming substrate 10.

(36) As in the smoking article 2 according to the first embodiment of the invention shown in FIG. 1 and described above, the aerosol-forming substrate 10 is heated by conduction to form an aerosol that is entrained in the drawn air as it flows through the aerosol-forming substrate 10. The drawn air and entrained aerosol pass downstream through the interior of the hollow tube 56 of the airflow directing element 54 to the aerosol-cooling element 14 and the spacer element 16, where they cool and condense. The cooled aerosol then passes downstream through the mouthpiece 18 of the smoking article 50 into the mouth of the user.

(37) The aerosol-cooling element 14 is located immediately downstream of the airflow directing element 54 and, similarly to the first embodiment, comprises a gathered sheet of biodegradable polymeric material such as, for example, polylactic acid.

(38) The spacer element 16 is located immediately downstream of the aerosol-cooling element 14 and comprises a cylindrical open-ended hollow paper or cardboard tube 30.

(39) The mouthpiece 18 is located immediately downstream of the spacer element 16. As shown in FIG. 3, the mouthpiece 18 is located at the proximal end of the smoking article 50 and comprises a cylindrical plug of suitable filtration material 32 such as, for example, cellulose acetate tow of very low filtration efficiency, wrapped in filter plug wrap 34.

(40) The non-combustible substantially air impermeable barrier coating 22 provided on the entire rear face of the combustible carbonaceous heat source 4 isolates the combustible carbonaceous heat source 4 from the airflow pathways through the smoking article 50 such that, in use, air drawn through the smoking article 50 along the airflow pathways does not directly contact the combustible carbonaceous heat source 4.

(41) As described with reference to the first embodiment shown in FIG. 1, in use, the second heat-conducting element 64 reduces radiative heat losses from the outer surfaces of the smoking article 50. This in turn helps maintain the temperature of the aerosol-forming substrate 10 to facilitate continued and enhanced aerosol delivery. As can be seen with reference to FIG. 3, the second heat-conducting element 64 only overlies the aerosol-forming substrate 10 and not the transfer element 12 as in the embodiment described with reference to FIG. 1.

(42) A smoking article according to a sixth embodiment of the invention (not shown) is of largely identical construction to the smoking article according to the fifth embodiment of the invention shown in FIG. 3. However, in the smoking article according to the fifth embodiment of the invention, the layer of heat-insulative material 40 overlying the first heat-conducting element 36 and underlying the second heat-conducting element 64 is omitted and the second heat-conducting element 64 is formed of a laminate material comprising an outer layer of heat-conductive material such as, for example, aluminium, and an inner layer of heat-insulative material such as, for example, paper.

(43) The specific embodiments shown in the Figures and described above are intended to illustrate the invention. However, other embodiments may be made without departing from the spirit and scope of the invention as defined in the claims, and it is to be understood that the specific embodiments described above are not intended to be limiting.