Aerosol-generating article having a compressible upstream element

Abstract

The aerosol-generating article (10) for producing an inhalable aerosol upon heating comprises a rod (12) of aerosol-generating substrate having a density of less than 300 mg per cubic centimeter, a downstream section (14) located downstream of the rod (12) of aerosol-generating substrate, the downstream section (14) extending from the downstream end of the rod (12) of aerosol-generating substrate to the mouth end (18) of the aerosol-generating article, and a compressible upstream element (42) located upstream of the rod (12) of aerosol-generating substrate, the upstream element (42) having a density of less than 140 mg per cubic centimeter.

Description

[Technical Field]

[0001] The present invention relates to an aerosol-generating article comprising an upstream element, and to a system comprising such an aerosol-generating article. [Background technology]

[0002] Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-containing substrate, is heated rather than combusted are known in the art. Typically, in such heated smoking articles, an aerosol is generated by transferring heat from a heat source to a physically separated aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in the air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

[0003] Numerous prior art documents disclose aerosol generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosol generating devices in which an aerosol is generated by heat transfer from one or more electric heater elements of the aerosol generating device to an aerosol-generating substrate of the heated aerosol-generating article. For example, an electrically heated aerosol generating device has been proposed that includes an internal heater blade adapted to be inserted into the aerosol-generating substrate. Alternatively, International Publication No. 2015 / 176898 proposes an inductively heated aerosol-generating article that includes an aerosol-generating substrate and a susceptor disposed within the aerosol-generating substrate. A further alternative is described in International Publication No. 2020 / 115151, which discloses an aerosol-generating article used in combination with an external heating system that includes one or more heating elements disposed around the outer surface of the aerosol-generating article.

[0004] Typically, aerosol-generating articles are manufactured with a substantially round cross-section so that the aerosol-generating substrate is cylindrical. The device cavity of a corresponding aerosol-generating device for heating the aerosol-generating article often has a cylindrical shape and size configured to substantially match the shape and size of the aerosol-generating substrate so that the aerosol-generating substrate can be easily received and held within the device cavity during heating.

[0005] However, it has been proposed to provide an improved aerosol generating device having a device cavity with a rectangular cross-section with opposing planar walls, at least one of which is provided with a heater element on its surface. Such an arrangement provides a potentially larger surface area over which the aerosol-generating substrate can be heated, significantly improving the efficiency of heating the aerosol-generating substrate. Such an arrangement also provides a more compact aerosol generating system that is easier to manufacture. However, consumers may have difficulty using such an aerosol generating device with a conventional cylindrical aerosol-generating article, as it may be difficult to compress or deform the cylindrical aerosol-generating substrate sufficiently to insert it into the rectangular device cavity. This is particularly true when the planar walls of the device cavity are relatively close together, such that the distance between the planar walls is significantly less than the diameter.

[0006] Therefore, there is a need for aerosol-generating articles that are adapted to be more compatible with aerosol-generating devices having rectangular device cavities. Summary of the Invention

[0007] According to the present invention, there is provided an aerosol-generating article for generating an inhalable aerosol upon heating, the aerosol-generating article extending from an oral end to a distal end. The aerosol-generating article may comprise a rod of aerosol-generating substrate. The rod of aerosol-generating substrate may have a density of less than 300 mg per cubic centimeter. The aerosol-generating article may further comprise a downstream section located downstream of the rod of aerosol-generating substrate, the downstream section extending from the downstream end of the rod of aerosol-generating substrate to the oral end of the aerosol-generating article. The aerosol-generating article may further comprise a compressible upstream element located upstream of the rod of aerosol-generating substrate. The upstream element may have a density of less than 140 mg per cubic centimeter.

[0008] According to the present invention, there is provided an aerosol-generating article for producing an inhalable aerosol when heated, the aerosol-generating article comprising: a rod of aerosol-generating substrate extending from a mouth end to a distal end thereof and having a density of less than 300 mg per cubic centimeter; a downstream section located downstream of the aerosol-generating substrate and extending from the downstream end of the rod of aerosol-generating substrate to the mouth end of the aerosol-generating article; and a compressible upstream element located upstream of the rod of aerosol-generating substrate, the upstream element having a density of less than 140 mg per cubic centimeter. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows a schematic side perspective view of a first aerosol-generating article for use in an aerosol-generating system according to the present invention; [Figure 2] 1 shows a schematic cross-sectional side view of a first aerosol-generating article for use in an aerosol-generating system according to the present invention. [Figure 3] 1 shows a schematic side cross-sectional view of an aerosol generating device for use in an aerosol-generating article system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The invention will now be further described with reference to the accompanying drawings.

[0011] 1 comprises a rod of aerosol-generating substrate 12 and a downstream section 14 located downstream of the rod of aerosol-generating substrate 12. The aerosol-generating article 10 thus extends from an upstream or distal end 16, which is substantially coincident with the upstream end of the rod 12, to a downstream or oral end 18, which is coincident with the downstream end of the downstream section 14. The downstream section 14 comprises a hollow tubular element 20 and a mouthpiece element 50.

[0012] The aerosol-generating article 10 has an overall length of about 45 millimeters and an outer diameter of about 7.1 millimeters.

[0013] The aerosol-generating substrate rod 12 has a length of 12 millimeters and contains shredded tobacco material. The aerosol-generating substrate rod 12 contains approximately 70 milligrams of shredded tobacco material containing 13 to 16 weight percent glycerin. The bulk density of the aerosol-generating substrate rod 12 is approximately 150 mg per cubic centimeter. The aerosol-generating substrate rod 12 is cylindrical and has a circular cross-section with an outer diameter of 7.1 millimeters. Therefore, because the cross-section is circular, the maximum diameter of the aerosol-generating substrate rod is also 7.1 millimeters. The initial cross-sectional area of ​​the aerosol-generating substrate rod is approximately 39.5 square millimeters.

[0014] The rods 12 of aerosol-generating substrate are individually wrapped in plug wrap (not shown).

[0015] The hollow tubular element 20 is located immediately downstream of the aerosol-generating substrate rod 12, and is longitudinally aligned with the rod 12. The upstream end of the hollow tubular element 20 abuts the downstream end of the aerosol-generating substrate rod 12.

[0016] The hollow tubular element 20 defines the hollow section of the aerosol-generating article 10. The hollow tubular element does not contribute substantially to the overall RTD of the aerosol-generating article. More specifically, the RTD of the hollow tubular element 20 is about 0 mmH2O.

[0017] 2, the hollow tubular element 20 is provided in the form of a hollow cylindrical tube made of cardboard. The hollow tubular element 20 defines an interior cavity 22 that extends from the upstream end of the hollow tubular element 20 all the way to the downstream end of the hollow tubular element 20. The interior cavity 22 is substantially empty, such that substantially unrestricted airflow is possible along the interior cavity 22. The hollow tubular element 20 does not substantially contribute to the overall RTD of the aerosol-generating article 10.

[0018] The hollow tubular element 20 has a length of about 21 millimeters, an outer diameter of about 7.1 millimeters, and an inner diameter of about 6.7 millimeters. The peripheral wall thickness of the hollow tubular element 20 is therefore about 0.25 millimeters.

[0019] The aerosol-generating article 10 includes a ventilation zone 30 provided along the hollow tubular element 20. More specifically, the ventilation zone 30 is located approximately 16 millimeters from the downstream end 18 of the article 10. The ventilation zone 30 is located approximately 12 mm downstream from the downstream end of the aerosol-generating substrate rod 12. The ventilation zone 30 is provided approximately 9 millimeters upstream from the upstream end of the mouthpiece element 50. The ventilation zone 30 includes a circumferential row of openings or perforations surrounding the hollow tubular element 20. The perforations in the ventilation zone 30 extend through the wall of the hollow tubular element 20 to allow fluid to enter the interior cavity 22 from outside the article 10. The perforations in the ventilation zone 30 have a permeability level of approximately 16 percent.

[0020] The aerosol-generating article 10 further comprises an upstream section 40 located upstream of the rod 12 of aerosol-generating substrate. The aerosol-generating article 10 therefore extends from a distal end 16 that is substantially coincident with the upstream end of the upstream section 40 to a mouth or downstream end 18 that is substantially coincident with the downstream end of the downstream section 14.

[0021] The upstream section 40 includes an upstream element 42 located immediately upstream of the aerosol-generating substrate rod 12, with the upstream element 42 being longitudinally aligned with the rod 12. The downstream end of the upstream element 42 abuts the upstream end of the aerosol-generating substrate rod 12. The upstream element 42 is provided in the form of a solid, cylindrical plug of cellulose acetate tow. The upstream element has a bulk density of approximately 120 mg per cubic centimeter. The upstream element 42 has a length of approximately 5 millimeters. The outer diameter of the upstream element 42 is approximately 7.1 millimeters.

[0022] The mouthpiece element 50 extends from the downstream end of the hollow tubular element 20 to the downstream or mouth end of the aerosol-generating article 10. The mouthpiece element 50 has a length of approximately 7 millimeters. The outer diameter of the mouthpiece element 50 is approximately 7.1 millimeters. The mouthpiece element 50 comprises a low-density cellulose acetate filter segment. The RTD of the mouthpiece element 50 is approximately 8 mmH2O. The mouthpiece elements 50 may be individually wrapped in plug wrap (not shown).

[0023] 1 and 2, article 10 includes an upstream wrapper 44 that surrounds upstream element 42, aerosol-generating substrate rod 12, and hollow tubular element 20. Ventilation zone 30 may also include a circumferential row of perforations disposed on upstream wrapper 44. The perforations in upstream wrapper 44 overlap with perforations provided on hollow tubular element 20. Thus, upstream wrapper 44 overlies the perforations of ventilation zone 30 provided on hollow tubular element 20.

[0024] The article 10 also includes a tipping wrapper 52 that surrounds the hollow tubular element 20 and the mouthpiece element 50. The tipping wrapper 52 overlies the portion of the upstream wrapper 44 that overlies the hollow tubular element 20. In this manner, the tipping wrapper 52 effectively connects the mouthpiece element 50 to the remaining components of the article 10. The width of the tipper wrapper 52 is approximately 26 mm. Additionally, the ventilation zone 30 may include a circumferential row of perforations provided on the tipping wrapper 52. The perforations in the tipping wrapper 52 overlap with the perforations provided on the hollow tubular element 20 and the upstream wrapper 44. Thus, the tipping wrapper 52 overlies the perforations of the ventilation zone 30 that are provided on the hollow tubular element 20 and the upstream wrapper 44.

[0025] Figure 3 shows an aerosol-generating device for use in combination with the aerosol-generating article 10 as shown in Figures 1 and 2. The aerosol-generating device is shown prior to insertion of the aerosol-generating article.

[0026] The aerosol generating device 100 shown in Figure 3 comprises a housing (or body) 102 extending between a mouth end 104 and a distal end (not shown). The housing 102 comprises a peripheral wall 106. The peripheral wall 106 defines an elongated heating chamber 108 for receiving the aerosol-generating article 10. The heating chamber 108 is defined by a closed distal end and an open mouth end. The mouth end 104 of the heating chamber 108 is located at the mouth end of the aerosol generating device 100. The aerosol-generating article 10 is configured to be received through the mouth end 104 of the heating chamber 108 and to abut the closed end of the heating chamber 108.

[0027] The heating chamber 108 has a substantially rectangular cross-section defining a pair of opposing flat walls 109 that are substantially parallel to one another and spaced about 2 millimeters from each other. During use, the aerosol-generating substrate rod 12 of the aerosol-generating article 10 is inserted between the opposing flat walls 109. Each of the opposing flat walls 109 is provided with a planar heating element (not shown) in the form of a resistive heating element. The heating chamber thus provides a heater assembly comprising a pair of opposing flat heater elements, or heater plates. During use, when the aerosol-generating substrate rod 12 is inserted between the opposing flat walls 109, the aerosol-generating substrate is heated from the top and bottom by the opposing heater elements.

[0028] The spacing between the opposing flat walls 109 of the heating chamber 108 is approximately 5 millimeters less than the diameter of the rod of aerosol-generating substrate 12 before the aerosol-generating article 10 is inserted into the aerosol-generating device 100. Thus, the rod of aerosol-generating substrate 12 is significantly compressed when inserted into the heating chamber 108, as will be described in more detail below.

[0029] An airflow channel 105 of the device is defined in a peripheral wall 106. The airflow channel 105 extends between an inlet 107 located at the mouth end of the aerosol-generating device 100 and the closed end of the heating chamber. Air can enter the aerosol-generating substrate 12 through an opening (not shown) provided in the closed end of the device cavity, ensuring fluid communication between the airflow channel 105 and the aerosol-generating substrate 12.

[0030] The aerosol-generating device 100 further includes a power supply (not shown) for supplying power to the heater element. A controller (not shown) is also provided for controlling such power supply to the heater element. The heater element is configured to controllably heat the aerosol-generating article 10 during use when the aerosol-generating article 10 is received within the device 100. The heater is preferably arranged to externally heat the aerosol-generating substrate 12 for optimal aerosol generation. The ventilation zone 30 is arranged to be exposed to the aerosol-generating article 10 when received within the aerosol-generating device 100.

[0031] To insert the aerosol-generating article 10 into the aerosol-generating device 100, the upstream element 42 and the rod of aerosol-generating substrate 12 must be compressed and flattened so that the cross-sectional dimensions of the upstream element 42 and the rod of aerosol-generating substrate 12 substantially match the cross-sectional dimensions of the heating chamber 108 of the aerosol-generating device. In particular, the upstream element and the rod of aerosol-generating substrate, both of which have initial diameters of 7.1 millimeters, must be compressed so that they are flattened in one dimension to a thickness that substantially matches the spacing between the opposing flat walls 109 of the heating chamber 108 (approximately 2 millimeters).

[0032] To insert the upstream end of the rod of aerosol-generating substrate 12 into the heating chamber 108, the consumer may need to squeeze or pinch the upstream end to flatten it. Once the end of the aerosol-generating article 10 is in place within the heating chamber 108, the aerosol-generating article 10 may then be pushed in an upstream direction, inserting as much of the rod of aerosol-generating substrate as possible into the heating chamber 108. The remaining portion of the rod of aerosol-generating substrate 12 is compressed and flattened as the aerosol-generating article 10 is pushed inward.

[0033] Once the aerosol-generating substrate rod 12 is fully received within the heating chamber 108, the rod has a rectangular cross-section with a height of 2 millimeters and a width of approximately 9 millimeters. This width corresponds to the final maximum diameter of the aerosol-generating substrate rod 12. Therefore, the final maximum diameter is approximately 1.25 times the initial maximum diameter. After compression of the aerosol-generating substrate rod 12, the rod has an increase in density of approximately 315 mg per cubic centimeter. Therefore, the final density of the aerosol-generating substrate is more than twice the initial density. The cross-sectional area is reduced to approximately 18 square millimeters. Therefore, the initial cross-sectional area is more than twice the final cross-sectional area.

[0034] Compressing the rod 12 of aerosol-generating substrate into a rectangular shape increases the contact area between the aerosol-generating substrate and the heater element and also reduces the distance heat must travel to effectively heat the entire aerosol-generating substrate within the rod. Thus, the aerosol-generating substrate can be heated very efficiently, resulting in minimal wastage of tobacco material.

[0035] The upstream element 42 is also compressed to a cross-sectional shape and size similar to that of the rod of aerosol-generating substrate 12. After compression of the upstream element 42, the upstream element has a final density of 150 mg per cubic centimeter. Thus, the final density is approximately 1.25 times its initial density. The changes in shape and dimensions of the upstream element 42 as a result of its compression are substantially the same as those defined above for the rod of aerosol-generating substrate.

[0036] As used herein, the term "aerosol-generating article" is used herein to refer to an article that includes an aerosol-generating substrate that is heated to generate and deliver an inhalable aerosol to a consumer. As used herein, the term "aerosol-generating substrate" means a substrate that has the ability to release volatile compounds upon heating to generate an aerosol.

[0037] As used herein, the term "aerosol-generating device" refers to a device that includes a heater element that interacts with an aerosol-generating substrate of an aerosol-generating article to generate an aerosol.

[0038] As used herein in connection with the present invention, the term "rod" is used to denote a generally elongated element, preferably a cylindrical element of substantially circular, oval or elliptical cross section.

[0039] As used herein, the term "longitudinal" refers to a direction corresponding to the major longitudinal axis of the aerosol-generating article extending between the upstream and downstream ends of the aerosol-generating article. As used herein, the terms "upstream" and "downstream" refer to the relative positions of elements (or portions of elements) of the aerosol-generating article with respect to the direction in which aerosol is transported through the aerosol-generating article during use.

[0040] During use, air is drawn longitudinally through the aerosol-generating article. The term "transverse" refers to a direction perpendicular to the longitudinal axis. Any reference to a "cross section" of an aerosol-generating article or a component of an aerosol-generating article refers to a transverse cross section, unless otherwise specified.

[0041] The term "length" refers to the dimension of a component of an aerosol-generating article in the longitudinal direction. For example, it can be used to refer to the dimension of a rod or downstream section in the longitudinal direction.

[0042] The term "density" as used herein in relation to the aerosol-generating substrate and the upstream element refers to the bulk density of the aerosol-generating substrate or the upstream element, respectively. For a rod of aerosol-generating substrate, this can be calculated by measuring the total weight of the aerosol-generating substrate and dividing it by the volume of the segment of the aerosol-generating substrate (excluding the wrapper). The initial density of the aerosol-generating substrate refers to the density of the aerosol-generating substrate before insertion into the aerosol-generating device. The final density of the aerosol-generating substrate refers to the density of the aerosol-generating substrate after it has been placed in the aerosol-generating device. For an upstream element, bulk density can be calculated by measuring the total weight of the upstream element and dividing it by the volume of the upstream element (excluding the wrapper).

[0043] Thus, the present invention provides an aerosol-generating article having a novel configuration, which includes a rod of aerosol-generating substrate having a relatively low density of less than 300 mg per cubic centimeter, in combination with an upstream element that also has a relatively low density of less than 140 mg per cubic centimeter. This combination of features provides the upstream element and rod of aerosol-generating substrate with greater compressibility than typical aerosol-generating articles. This advantageously facilitates the compression and deformation of the aerosol-generating substrate required for insertion of the aerosol-generating article into an aerosol-generating device having a heating chamber with a cross-section other than that of the rod of aerosol-generating substrate, particularly a cross-section that is rectangular, as discussed above.

[0044] The relatively low density of the rod of aerosol-generating substrate allows the aerosol-generating substrate to be compressed more easily, and the initial density of the rod of aerosol-generating substrate before inserting the aerosol-generating article into the aerosol-generating device is selected so that the final density of the rod of aerosol-generating substrate after insertion into the aerosol-generating device and compression provides an appropriate level of resistance to withdrawal (RTD).

[0045] Similarly, the relatively low density of the upstream element also allows it to be compressed more easily than conventional upstream elements. As noted above, compressing the upstream element to the same extent as the aerosol-generating substrate rod is likely essential for inserting the aerosol-generating article into an aerosol-generating device having a rectangular heating chamber. Therefore, the inclusion of the upstream element should facilitate, rather than hinder, the insertion of the aerosol-generating article into the heating chamber of the aerosol-generating device. The inclusion of the upstream element may provide additional protection for the end of the aerosol-generating substrate rod during insertion into the article cavity, thereby minimizing the risk of damage to the substrate. This may be particularly important in view of the increased manipulation of the aerosol-generating substrate rod that is likely to be required for insertion into the heating chamber.

[0046] The upstream element additionally provides further technical advantages. The upstream element advantageously prevents direct physical contact with the upstream end of the aerosol-generating substrate. For example, if the aerosol-generating substrate comprises a susceptor element, the upstream element may prevent direct physical contact with the upstream end of the susceptor element. This helps to prevent displacement or deformation of the susceptor element during handling or transport of the aerosol-generating article. This, in turn, helps to fix the shape and position of the susceptor element. Furthermore, the presence of the upstream element helps to prevent loss of the substrate, which may be particularly advantageous in the present invention where the initial density of the aerosol-generating substrate is relatively low. If the aerosol-generating substrate comprises shredded tobacco, such as tobacco cut filler, the upstream section or element thereof may additionally help to prevent loss of loose tobacco particles from the upstream end of the article.

[0047] The upstream element may also provide at least some coverage of the upstream end of the aerosol-generating substrate that would otherwise be exposed, and therefore may provide some additional protection to the aerosol-generating substrate during storage.

[0048] The upstream element may also provide an improved appearance to the upstream end of the aerosol-generating article. Additionally, if desired, the upstream element may be used to provide information about the aerosol-generating article, such as the brand, flavor, content, or details of the aerosol-generating device in which the article is intended to be used.

[0049] The upstream element may have a density of less than 200 grams per cubic centimeter, or less than 175 grams per cubic centimeter, or less than 150 grams per cubic centimeter. According to the present invention, the upstream element has a density of less than 140 grams per cubic centimeter. Preferably, the density of the upstream element is less than 138 grams per cubic centimeter, more preferably less than 136 grams per cubic centimeter, more preferably less than 134 grams per cubic centimeter, more preferably less than 132 grams per cubic centimeter, more preferably less than 130 grams per cubic centimeter.

[0050] The upstream element preferably has a density of at least 85 mg per cubic centimeter, more preferably at least 90 mg per cubic centimeter, more preferably at least 95 mg per cubic centimeter, more preferably at least 100 mg per cubic centimeter, more preferably at least 105 mg per cubic centimeter, more preferably at least 110 mg per cubic centimeter, more preferably at least 120 mg per cubic centimeter.

[0051] For example, the upstream element may have a density of 85 mg per cubic centimeter to 140 grams per cubic centimeter, or 90 mg per cubic centimeter to 138 grams per cubic centimeter, or 95 mg per cubic centimeter to 136 grams per cubic centimeter, or 100 mg per cubic centimeter to 134 grams per cubic centimeter, or 105 mg per cubic centimeter to 132 grams per cubic centimeter, or 110 mg per cubic centimeter to 130 grams per cubic centimeter, or 120 mg per cubic centimeter to 130 mg per cubic centimeter.

[0052] Reducing the density of the upstream element compared to the typical density of such elements increases the compressibility of the upstream element.

[0053] The upstream element is adapted to compress the upstream element and the rod of aerosol-generating substrate to a final density after insertion into the heating chamber of the aerosol-generating device. The upstream element is preferably adapted to be compressible to a final density that is at least 1.1 times, more preferably at least 1.25 times, more preferably 1.5 times, more preferably 1.75 times, or more preferably 2 times the initial density. The upstream element may be compressible to a final density that is up to 4 times the initial density.

[0054] For example, the upstream element may be adapted to be compressible to a final density that is 1.1 to 4 times, or 1.25 to 4 times, or 1.5 to 4 times, or 1.75 to 4 times, or 2 to 4 times, or 1.1 to 3 times, or 1.25 to 3 times, or 1.5 to 3 times, or 1.75 to 3 times, or 2 to 3 times the initial density.

[0055] Preferably, the upstream element is adapted to be compressible to a final density of at least 100 mg per cubic centimeter, more preferably at least 110 mg per cubic centimeter, more preferably at least 120 mg per cubic centimeter, more preferably at least 125 mg per cubic centimeter, more preferably at least 130 mg per cubic centimeter, more preferably at least 135 mg per cubic centimeter, more preferably at least 140 mg per cubic centimeter.

[0056] Preferably, the upstream element is adapted to be compressible to a final density of less than 350 mg per cubic centimeter, more preferably less than 300 mg per cubic centimeter, more preferably less than 275 mg per cubic centimeter, more preferably less than 250 mg per cubic centimeter, more preferably less than 225 mg per cubic centimeter, more preferably less than 200 mg per cubic centimeter, more preferably less than 175 mg per cubic centimeter.

[0057] For example, the upstream element is preferably adapted to be compressible to a final density of from 100 mg per cubic centimeter to 350 mg per cubic centimeter, or from 110 mg per cubic centimeter to 300 mg per cubic centimeter, or from 120 mg per cubic centimeter to 275 mg per cubic centimeter, or from 125 mg per cubic centimeter to 250 mg per cubic centimeter, or from 130 mg per cubic centimeter to 225 mg per cubic centimeter, or from 135 mg per cubic centimeter to 200 mg per cubic centimeter, or from 140 mg per cubic centimeter to 175 mg per cubic centimeter.

[0058] The upstream element may be made of any material suitable for use in an aerosol-generating article that provides the desired degree of compressibility. Suitable materials for forming the upstream element include filter material, ceramic, polymeric material, cellulose acetate, cardboard, zeolite, or an aerosol-generating substrate.

[0059] In a preferred embodiment, the upstream element is formed from a fibrous filtering material, and most preferably, the upstream element is formed from a segment of cellulose acetate tow.

[0060] Preferably, the upstream element is formed of a fibrous filtration material having a denier per filament (dpf) of less than 12, or less than 8, or less than 4. More preferably, the denier per filament (dpf) is less than 3. The denier per filament (dpf) of the fibrous filtration material is preferably less than 2.9, more preferably less than 2.8, more preferably less than 2.7, more preferably less than 2.6.

[0061] Preferably, the denier per filament (dpf) of the fibrous filtration material is at least 2, more preferably at least 2.1, more preferably at least 2.2, more preferably at least 2.3, more preferably at least 2.4.

[0062] For example, the denier per filament (dpf) may be 2 to 12, or 2 to 8, or 2 to 4, or 2 to 3, or 2.1 to 2.9, or 2.2 to 2.8, or 2.3 to 2.7, or 2.4 to 2.6. The denier per filament may be about 2.5.

[0063] The denier per filament corresponds to the average denier of the individual fibers in the upstream element and is the weight in grams of a single fiber or filament having a length of 9000 meters. Therefore, in the present invention, the dpf value indicates the thickness of each individual fiber in the upstream element. The denier per filament is expressed in units of denier, with 1 denier equaling 1 gram per 9000 meters. The dpf of a filter or filter segment can be easily determined based on measuring the weight and length of a representative sample of fibers from the filter or filter segment.

[0064] Thus, the fibrous filtration material forming the upstream element has a relatively low denier per filament, which further enhances the compressibility of the upstream element.

[0065] Preferably, the upstream element is formed of a fibrous filtration material having a total denier of less than 30,000, more preferably less than 25,000. The total denier may be about 20,000.

[0066] The "total denier" of a filtration material defines the total weight in grams of 9000 meters of combined fibers forming the filtration material. Thus, the total denier of a filter segment is equal to the denier per filament multiplied by the total number of fibers in the filter segment.

[0067] When the upstream element is formed of a fibrous filtration material, the fibrous filtration material preferably includes a filter plasticizer. The amount of filter plasticizer in the upstream element is preferably less than 4 weight percent, more preferably less than 3.9 weight percent, more preferably less than 3.8 weight percent, more preferably less than 3.7 weight percent, and more preferably less than 3.6 weight percent, based on the total weight of the upstream element (excluding the wrapper). The amount of filter plasticizer in the upstream element is preferably at least 3 weight percent, more preferably at least 3.1 weight percent, more preferably at least 3.2 weight percent, more preferably at least 3.3 weight percent, and more preferably at least 3.4 weight percent, based on the total weight of the upstream element.

[0068] For example, the upstream element may have a filter plasticizer content of 3 to 4 weight percent, or 3.1 to 3.9 weight percent, or 3.2 to 3.8 weight percent, or 3.3 to 3.7 weight percent, or 3.4 to 3.6 weight percent, based on the total weight of the upstream element. The upstream element may have a filter plasticizer content of about 3.5 weight percent, based on the total weight of the upstream element.

[0069] Thus, the amount of filter plasticizer in the fibrous filtration material is relatively low, which further improves the compressibility of the upstream element. A relatively low level of filter plasticizer can also ensure that compression of the upstream element does not result in an unacceptable increase in the resistance to draw (RTD) of the upstream element. In general, maintaining a relatively low level of filter plasticizer advantageously allows for better control of the RTD as the upstream element is compressed. Providing a higher level of filter plasticizer may make it more difficult to compress the upstream element, but may also set up undesirable channels outside the upstream element as it is compressed, resulting in an unacceptable decrease in overall RTD.

[0070] Suitable filter plasticizers for use in the upstream element of the aerosol-generating article of the present invention will be known to those skilled in the art. Preferably, the filter plasticizer is triacetin. Preferably, the upstream element comprises cellulose acetate tow containing triacetin as the filter plasticizer.

[0071] The upstream element may alternatively be formed from cardboard or paper material.

[0072] In certain preferred embodiments, the upstream element is formed of a solid, cylindrical plug element having a filled cross-section. Such a plug element may be referred to as a "plain" element. The solid plug element may be porous, but does not have a tubular configuration and therefore does not provide a longitudinal flow channel. Preferably, the solid plug element has a substantially uniform cross-section.

[0073] In such embodiments, the upstream element preferably has a resistance to withdrawal (RTD) of less than 25 millimeters of H2O, or less than 22 millimeters of H2O, or less than 20 millimeters of H2O. Preferably, the upstream element has an RTD of at least 10 millimeters of H2O, or at least 12 millimeters of H2O, or at least 14 millimeters of H2O, or at least 16 millimeters of H2O. For example, the upstream element may have an RTD of between 10 millimeters of H2O and 25 millimeters of H2O, or between 12 millimeters of H2O and 22 millimeters of H2O, or between 14 millimeters of H2O and 20 millimeters of H2O, or between 16 millimeters of H2O and 20 millimeters of H2O.

[0074] Unless otherwise specified, the resistance to draw (RTD) of a component or aerosol-generating article is measured in accordance with ISO 6565-2015. RTD refers to the pressure required to pump air through the entire length of the component. The terms "pressure drop" or "draw resistance" of a component or article may also refer to "resistance to draw." Such terms generally refer to measurements in accordance with ISO 6565-2015 performed normally under test at a temperature of 22 degrees Celsius, a pressure of 101 kPa (approximately 760 Torr), and 60% relative humidity, with a volumetric flow rate of 17.5 milliliters per second at the output or downstream end of the measured component. Smoking conditions and smoking machine specifications are provided in ISO Standard 3308 (ISO 3308:2000). Conditioning and testing atmospheres are provided in ISO Standard 3402 (ISO 3402:1999).

[0075] In other preferred embodiments, the upstream element is formed from a hollow tubular segment defining a longitudinal cavity that provides an unrestricted flow channel. In such embodiments, the upstream element can provide protection for the aerosol-generating substrate, as described above, while having only a minimal effect on the overall resistance to draw (RTD) and filtration properties of the article.

[0076] Preferably, the diameter of the longitudinal cavity of the hollow tubular segment forming the upstream element is at least about 4 millimeters, more preferably at least about 4.5 millimeters, more preferably at least about 5 millimeters, more preferably at least about 5.5 millimeters. Preferably, the diameter of the longitudinal cavity is maximized to minimize the RTD of the upstream section or element. The inner diameter of the upstream element may be about 5.1 mm.

[0077] Preferably, the wall thickness of the hollow tubular segment is less than about 2 millimeters, more preferably less than about 1.5 millimeters, more preferably less than about 1.25 millimeters. The wall thickness of the hollow tubular segment defining the upstream element may be about 1 mm.

[0078] In such embodiments, the upstream element preferably has an RTD of less than 10 millimeters HO, more preferably less than 5 millimeters HO, and even more preferably less than 2.5 millimeters HO. Preferably, in such embodiments, the upstream element has an RTD of at least 0.1 millimeters HO, or at least about 0.25 millimeters HO, or at least about 0.5 millimeters HO. For example, the upstream element may have an RTD of between 0.1 millimeters HO and 10 millimeters HO, or between 0.25 millimeters HO and 5 millimeters HO, or between 0.5 millimeters HO and 2.5 millimeters HO.

[0079] Preferably, prior to insertion of the aerosol-generating article into the aerosol-generating device, the upstream element has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. Preferably, the outer diameter of the upstream element, before any compression, is between about 6 mm and about 8 mm, more preferably between about 7 mm and about 7.5 mm. Preferably, the upstream element has an outer diameter that is about 7.1 mm.

[0080] Preferably, the upstream element has a length of 2 to 8 millimeters, more preferably 3 to 7 millimeters, and even more preferably 4 to 6 millimeters. In a particularly preferred embodiment, the upstream element has a length of about 5 millimeters. The length of the upstream section or element may be advantageously varied to provide a desired overall length for the aerosol-generating article. For example, if it is desired to reduce the length of one of the other components of the aerosol-generating article, the length of the upstream section or element may be increased to maintain the same overall length of the article.

[0081] Additionally, the length of the upstream element can be used to control the position of the aerosol-generating article within the heating chamber of the aerosol-generating device relative to the article intended to be externally heated, thereby advantageously ensuring that the position of the aerosol-generating substrate within the heating chamber can be optimized for heating, and the position of any ventilation can also be optimized.

[0082] The upstream element is preferably surrounded by a wrapper, such as plug wrap, which is preferably adapted to allow the necessary compression of the upstream element when the aerosol-generating article is inserted into the aerosol-generating device.

[0083] Preferably, the upstream element is surrounded by a wrapper having a thickness of less than 50 microns, more preferably less than 45 microns, more preferably less than 40 microns, more preferably less than 35 microns, more preferably less than 30 microns.

[0084] Preferably, the upstream element is surrounded by a wrapper having a basis weight of less than 35 grams per square meter, more preferably less than 30 grams per square meter, more preferably less than 25 grams per square meter, more preferably less than 20 grams per square meter.

[0085] Therefore, the wrapper surrounding the upstream element preferably has a relatively low thickness and basis weight so that the wrapper allows for the required level of compression of the upstream element.

[0086] The upstream element is preferably connected to the rod, and optionally to at least part of the downstream section, of the aerosol-generating substrate by an outer wrapper as described herein, which also preferably has a relatively low thickness and basis weight to allow the necessary level of compression of the upstream element and the aerosol-generating substrate.

[0087] Preferably, the outer wrapper has a thickness of less than 75 microns, more preferably less than 70 microns, more preferably less than 65 microns, more preferably less than 60 microns, more preferably less than 55 microns.

[0088] Preferably, the upstream element is surrounded by a wrapper having a basis weight of less than 50 grams per square meter, more preferably less than 45 grams per square meter, more preferably less than 40 grams per square meter, more preferably less than 35 grams per square meter.

[0089] A rod of aerosol-generating substrate, as defined above, is provided downstream of the upstream element. Preferably, the upstream end of the rod of aerosol-generating substrate abuts the downstream end of the upstream element.

[0090] According to the present invention, the rod of aerosol-generating substrate has a density of less than 300 mg per cubic centimetre, more preferably less than 275 mg per cubic centimetre, more preferably less than 250 mg per cubic centimetre, more preferably less than 225 mg per cubic centimetre, more preferably less than 200 mg per cubic centimetre, more preferably less than 175 mg per cubic centimetre, more preferably less than 150 mg per cubic centimetre, more preferably less than 125 mg per cubic centimetre, which corresponds to the initial density of the rod of aerosol-generating substrate before insertion of the aerosol-generating article into the aerosol-generating device.

[0091] Preferably, the density of the rods of the aerosol-generating substrate is at least 75 mg per cubic centimeter, more preferably at least 80 mg per cubic centimeter, more preferably at least 85 mg per cubic centimeter, more preferably at least 90 mg per cubic centimeter, more preferably at least 95 mg per cubic centimeter, more preferably at least 100 mg per cubic centimeter, more preferably at least 105 mg per cubic centimeter, more preferably at least 110 mg per cubic centimeter.

[0092] For example, the density of the rods of the aerosol-generating substrate may be from 75 mg per cubic centimeter to 300 mg per cubic centimeter, or from 80 mg per cubic centimeter to 275 mg per cubic centimeter, or from 85 mg per cubic centimeter to 250 mg per cubic centimeter, or from 90 mg per cubic centimeter to 225 mg per cubic centimeter, or from 95 mg per cubic centimeter to 200 mg per cubic centimeter, or from 100 mg per cubic centimeter to 175 mg per cubic centimeter, or from 105 mg per cubic centimeter to 150 mg per cubic centimeter, or from 110 mg per cubic centimeter to 125 mg per cubic centimeter.

[0093] The rod of aerosol-generating substrate is adapted to be compressible to a final density after insertion of the rod into the heating chamber of the aerosol-generating device. Preferably, the rod of aerosol-generating substrate is adapted to be compressible to a final density that is at least 1.1 times, more preferably at least 1.25 times, more preferably at least 1.5 times, more preferably at least 1.75 times, and more preferably twice its initial density. The rod of aerosol-generating substrate may be compressible to a final density that is up to four times its initial density.

[0094] For example, the rod of aerosol-generating substrate may be adapted to be compressible to a final density that is from 1.1 to 4 times its initial density, or from 1.25 to 4 times its initial density, or from 1.5 to 4 times its initial density, or from 1.75 to 4 times its initial density, or from 2 to 4 times its initial density, or from 1.1 to 3 times its initial density, or from 1.25 to 3 times its initial density, or from 1.5 to 3 times its initial density, or from 1.75 to 3 times its initial density, or from 2 to 3 times its initial density.

[0095] Preferably, the rod of aerosol-generating substrate is adapted to be compressible to a final density of at least 150 mg per cubic centimeter, more preferably at least 175 mg per cubic centimeter, more preferably at least 200 mg per cubic centimeter, more preferably at least 225 mg per cubic centimeter, more preferably at least 250 mg per cubic centimeter, more preferably at least 275 mg per cubic centimeter, more preferably at least 300 mg per cubic centimeter.

[0096] Preferably, the rod of aerosol-generating substrate is adapted to be compressible to a final density of less than 500 mg per cubic centimeter, more preferably less than 475 mg per cubic centimeter, more preferably less than 450 mg per cubic centimeter, more preferably less than 425 mg per cubic centimeter, more preferably less than 400 mg per cubic centimeter, more preferably less than 375 mg per cubic centimeter, more preferably less than 350 mg per cubic centimeter.

[0097] For example, the rod of aerosol-generating substrate may be adapted to be compressible to a final density of from 150 mg per cubic centimeter to 500 mg per cubic centimeter, or from 175 mg per cubic centimeter to 475 mg per cubic centimeter, or from 200 mg per cubic centimeter to 450 mg per cubic centimeter, or from 225 mg per cubic centimeter to 425 mg per cubic centimeter, or from 250 mg per cubic centimeter to 400 mg per cubic centimeter, or from 275 mg per cubic centimeter to 375 mg per cubic centimeter, or from 300 mg per cubic centimeter to 350 mg per cubic centimeter.

[0098] Preferably, the rod of the aerosol-generating substrate has a density that is relatively similar to that of the upstream element, so that it is easier to compress the upstream element and the rod of the aerosol-generating substrate to the same extent when inserting the aerosol-generating article into an aerosol-generating device.

[0099] Preferably, the density of the rods of the aerosol-generating substrate is at least 0.6 times, more preferably at least 0.7 times, more preferably at least 0.8 times the density of the upstream element.

[0100] Preferably, the density of the rods of the aerosol-generating substrate is less than 1.4 times, more preferably less than 1.3 times, more preferably less than 1.3 times the density of the upstream element.

[0101] For example, the density of the rods of the aerosol-generating substrate may be 0.6 to 1.4 times the density of the upstream element, or 0.7 to 1.3 times the density of the upstream element, or 0.8 to 1.2 times the density of the upstream element. The density of the rods of the aerosol-generating substrate may be substantially the same as or about the same as the density of the upstream element.

[0102] Preferably, the rod of aerosol-generating substrate has a substantially circular cross-section before insertion of the aerosol-generating article into the aerosol-generating device. After insertion of the aerosol-generating article into the aerosol-generating device, the rod of aerosol-generating substrate preferably has a substantially rectangular cross-section. Alternatively, after insertion of the aerosol-generating article into the aerosol-generating device, the rod of aerosol-generating substrate may have a substantially elliptical cross-section.

[0103] Preferably, the aerosol-generating substrate rod has a length of at least 8 mm, more preferably at least 9 mm, and even more preferably at least 10 mm. Preferably, the aerosol-generating substrate rod has a length of less than 16 mm, more preferably less than 15 mm, and even more preferably less than 14 mm. For example, the aerosol-generating substrate rod may have a length of 8 mm to 16 mm, or 9 mm to 15 mm, or 10 mm to 14 mm. In a particularly preferred embodiment, the aerosol-generating substrate rod has a length of about 12 mm.

[0104] The ratio of the length of the rod of the aerosol-generating substrate to the total length of the aerosol-generating article is preferably at least 0.10, more preferably at least 0.15, more preferably at least 0.20, and more preferably at least 0.25. Preferably, the ratio of the length of the rod of the aerosol-generating substrate to the total length of the aerosol-generating article is less than 0.50, more preferably less than 0.45, more preferably less than 0.40, and more preferably less than 0.35. For example, the ratio of the length of the rod of the aerosol-generating substrate to the total length of the aerosol-generating article may be 0.1 to 0.5, or 0.15 to 0.45, or 0.2 to 0.4, or 0.25 to 0.35.

[0105] Prior to insertion of the aerosol-generating article into the aerosol-generating device, the rod of aerosol-generating substrate preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article.

[0106] Preferably, before inserting the aerosol-generating article into the aerosol-generating device, the rod of aerosol-generating substrate has an outer diameter of at least 5 millimeters, more preferably at least 6 millimeters, more preferably at least 7 millimeters. Before inserting the aerosol-generating article into the aerosol-generating device, the rod of aerosol-generating substrate preferably has an outer diameter of less than 12 millimeters, more preferably less than 10 millimeters, more preferably less than 8 millimeters. For example, the outer diameter may be between 5 millimeters and 12 millimeters, or between 6 millimeters and 10 millimeters, or between 7 millimeters and 8 millimeters. In a particularly preferred embodiment, the rod of aerosol-generating substrate has an outer diameter of about 7.1 millimeters.

[0107] Preferably, the rod of aerosol-generating substrate has a substantially uniform cross-section along the length of the rod, and most preferably, the rod of aerosol-generating substrate has a substantially circular cross-section prior to insertion of the aerosol-generating article into the aerosol-generating device.

[0108] The aerosol-generating substrate may be a solid aerosol-generating substrate. Suitable types of materials for use in aerosol-generating substrates are described below and include, for example, tobacco cut filler, homogenized tobacco materials such as cast leaf, aerosol-generating films, and gel compositions.

[0109] The aerosol-generating substrate preferably includes an aerosol former. The aerosol former can be any suitable known compound or mixture of compounds that promotes the formation of a dense, stable aerosol during use. The aerosol former can promote the aerosol to be substantially resistant to thermal decomposition at temperatures typically encountered during use of the aerosol-generating article. Suitable aerosol formers include, for example, polyhydric alcohols (e.g., triethylene glycol, 1,3-butanediol, propylene glycol, glycerin, etc.), esters of polyhydric alcohols (e.g., glycerol mono-, di-, or triacetate, etc.), aliphatic esters of mono-, di-, or polycarboxylic acids (e.g., dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.), and combinations thereof.

[0110] The aerosol former preferably comprises one or more of glycerin and propylene glycol. The aerosol former may consist of glycerin, or propylene glycol, or a combination of glycerin and propylene glycol.

[0111] In certain embodiments, the aerosol-generating substrate preferably comprises at least 5 weight percent aerosol formers, based on the dry weight of the aerosol-generating substrate, more preferably at least 10 weight percent, and even more preferably at least 15 weight percent. In such embodiments, the aerosol-generating substrate preferably comprises no more than 30 weight percent aerosol formers, more preferably no more than 25 weight percent, and even more preferably no more than 20 weight percent aerosol formers, based on the dry weight of the aerosol-generating substrate. For example, the aerosol-generating substrate may have an aerosol-former content of 5 to 30 weight percent, or 10 to 25 weight percent, or about 15 to about 20 weight percent, based on the dry weight of the aerosol-generating substrate. Thus, in such embodiments, the aerosol-former content is relatively low.

[0112] In other embodiments, the aerosol-generating substrate preferably comprises at least 40 weight percent aerosol formers, based on the dry weight of the aerosol-generating substrate, more preferably at least 45 weight percent, and more preferably at least 50 weight percent. In such embodiments, the aerosol-generating substrate preferably comprises no more than 80 weight percent aerosol formers, based on the dry weight of the aerosol-generating substrate, more preferably no more than 75 weight percent, and more preferably no more than 70 weight percent. For example, the aerosol-generating substrate may have an aerosol-former content of 40 to 80 weight percent, or 45 to 75 weight percent, or 50 to 70 weight percent, based on the dry weight of the aerosol-generating substrate. Thus, in such embodiments, the aerosol-former content is relatively high.

[0113] In some preferred embodiments, the aerosol-generating substrate comprises tobacco material. For example, the aerosol-generating substrate may comprise shredded tobacco material. For example, the shredded tobacco material may be in the form of cut filler, as described in more detail below. Alternatively, the shredded tobacco material may be in the form of shredded sheets of homogenized tobacco material. Suitable homogenized tobacco materials for use in the present invention are described below.

[0114] Within the context of this specification, the term "cut filler" is used to refer to a blend of shredded plant material, such as tobacco plant material, including, inter alia, one or more of leaf laminae, processed stems and veins, and homogenized plant material.

[0115] Cut filler may also include other cuts, filler tobacco, or casings.

[0116] Preferably, the cut filler comprises at least 25 percent plant leaf lamina, more preferably at least 50 percent plant leaf lamina, even more preferably at least 75 percent plant leaf lamina, and most preferably at least 90 percent plant leaf lamina. Preferably, the plant material is one of tobacco, mint, tea, and cloves. Most preferably, the plant material is tobacco. However, the present invention is equally applicable to other plant materials capable of releasing a substance upon application of heat and subsequently forming an aerosol.

[0117] The cut filler suitable for use in the present invention may generally be similar to the cut filler used in conventional smoking articles. The cut width of the cut filler may preferably be 0.3 mm to 2.0 mm, or 0.5 mm to 1.2 mm, or 0.6 mm to 0.9 mm.

[0118] Preferably, the strands have a length of from about 10 millimeters to about 40 millimeters, and the strands are then aligned to form a rod of the aerosol-generating substrate.

[0119] In a preferred embodiment, the weight of the cut filler is between 25 milligrams and 150 milligrams, preferably between 30 milligrams and 125 milligrams, and more preferably between 40 milligrams and 100 milligrams. This amount of cut filler typically provides sufficient material for aerosol formation during the initial puff.

[0120] Preferably, the cut filler is immersed in the aerosol former. The immersion of the cut filler can be achieved by spraying or other suitable application methods. The aerosol former can be applied to the blend during the preparation of the cut filler. For example, the aerosol former can be applied to the blend in a direct conditioning casing cylinder (DCCC). Conventional machines can be used to apply the aerosol former to the cut filler. Suitable aerosol formers are presented above.

[0121] The aerosol former in the cut filler preferably comprises one or more of glycerol and propylene glycol. The aerosol former may comprise glycerol, or propylene glycol, or a combination of glycerin and propylene glycol.

[0122] In another preferred embodiment, the aerosol-generating substrate comprises homogenized plant material, preferably homogenized tobacco material.

[0123] As used herein, the term "homogenized plant material" encompasses any plant material formed by agglomeration of plant particles. For example, a sheet or web of homogenized tobacco material for an aerosol-generating substrate of the present invention may be formed by agglomerating particles of tobacco material obtained by grinding, crushing, or comminuting plant material and, optionally, one or more of tobacco lamina and tobacco stems. Homogenized plant material may be produced by molding, extrusion, a papermaking process, or any other suitable process known in the art.

[0124] The homogenized plant material may be provided in any suitable form.

[0125] In some embodiments, the homogenized plant material may be in the form of one or more sheets. As used herein with respect to the present invention, the term "sheet" refers to a layered element having a width and length that is substantially greater than its thickness.

[0126] The homogenized plant material may be in the form of a plurality of pellets or granules.

[0127] The homogenized plant material may be in the form of multiple strands, pieces, or fragments. As used herein, the term "strand" refers to an elongated element of material having a length that is substantially greater than its width and thickness. The term "strand" should be considered to encompass pieces, fragments, and any other homogenized plant material having a similar morphology. Strands of homogenized plant material may be formed from a sheet of homogenized plant material, for example, by cutting or chopping, or by other methods, such as extrusion.

[0128] The aerosol former content of the homogenized tobacco material is preferably within the range defined above for aerosol-generating substrates having relatively low aerosol former contents.

[0129] In another preferred embodiment, the aerosol-generating substrate is in the form of an aerosol-generating film comprising a cellulosic film-forming agent, nicotine, and an aerosol former. The aerosol-generating film may further comprise a cellulosic reinforcing agent. The aerosol-generating film may further comprise water, preferably less than 30 weight percent water.

[0130] The term "film" as used herein refers to a solid layered element having a thickness smaller than its width or length. The film may be self-supporting. In other words, even if the film is obtained by casting a film-forming formulation on a support surface, the film may have cohesive and mechanical properties that allow it to be separated from the support surface. Alternatively, the film may be placed on a support or sandwiched between other materials. This may enhance the mechanical stability of the film.

[0131] The aerosol-forming film has an aerosol-forming content within the ranges defined above for aerosol-forming substrates having relatively high aerosol-forming content.

[0132] In the context of the present invention, the term "cellulosic film former" is used to denote a cellulose polymer capable of forming a continuous film by itself or in the presence of an auxiliary thickener. Preferably, the cellulose film former is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethyl methylcellulose (HEMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and combinations thereof. In a particularly preferred embodiment, the cellulose film former is HPMC.

[0133] The aerosol-generating film may have a cellulosic film-forming agent content of from 10 weight percent to 40 weight percent, or from 15 weight percent to 35 weight percent, or from 20 weight percent to 30 weight percent, on a dry weight basis.

[0134] The aerosol-generating film preferably further comprises a cellulosic reinforcing agent, preferably selected from the group consisting of cellulose fibers, microcrystalline cellulose (MCC), cellulose powder, and combinations thereof.

[0135] The aerosol-generating film may have a cellulosic strength agent content of from 0.5 weight percent to 40 weight percent on a dry weight basis, or from 5 weight percent to 30 weight percent on a dry weight basis, or from 10 weight percent to 25 weight percent on a dry weight basis.

[0136] The aerosol-generating film may further comprise carboxymethylcellulose, preferably sodium carboxymethylcellulose.

[0137] The aerosol-generating film may have a carboxymethylcellulose content of from 1 weight percent to 15 weight percent, or from 2 weight percent to 12 weight percent, or from 4 weight percent to 10 weight percent on a dry weight basis.

[0138] Preferably, the aerosol-generating film comprises nicotine. As used herein in connection with the present invention, the term "nicotine" is used to refer to nicotine, nicotine base, or nicotine salts. In embodiments where the aerosol-generating film comprises nicotine base or nicotine salts, the amounts of nicotine recited herein are the amounts of free base nicotine or the amounts of protonated nicotine, respectively.

[0139] The aerosol-generating film may include natural or synthetic nicotine.

[0140] The aerosol-generating film may comprise one or more monobasic nicotine salts. As used herein in connection with the present invention, the term "monobasic nicotine salt" is used to refer to a nicotine salt of a monobasic acid.

[0141] Preferably, the aerosol-generating film comprises, on a dry weight basis, from 0.5 weight percent to 10 weight percent nicotine, or from 1 weight percent to about 8 weight percent nicotine, or from about 2 weight percent to about 6 weight percent nicotine.

[0142] The aerosol-generating film may be a substantially tobacco-free aerosol-generating film.

[0143] In a preferred embodiment, the aerosol-generating film comprises an acid. More preferably, the aerosol-generating film comprises one or more organic acids. Even more preferably, the aerosol-generating film comprises one or more carboxylic acids. In a particularly preferred embodiment, the acid is lactic acid, benzoic acid, fumaric acid, or levulinic acid.

[0144] Preferably, the aerosol-generating film comprises, on a dry weight basis, 0.25 to 3.5 weight percent acid, or 0.5 to 3 weight percent acid, or about 1 to 2.5 weight percent acid.

[0145] The aerosol-generating film may have a thickness of about 0.1 millimeter to about 1 millimeter, more preferably about 0.1 millimeter to about 0.75 millimeter, and even more preferably about 0.1 millimeter to about 0.5 millimeter. In particularly preferred embodiments, a layer of the film-forming composition is formed having a thickness of about 50 micrometers to 400 micrometers, more preferably about 100 micrometers to 200 micrometers.

[0146] The aerosol-generating film may optionally be provided within the aerosol-generating segment on a suitable carrier element.

[0147] In an alternative embodiment of the present invention, the aerosol-generating substrate may comprise a gel composition comprising nicotine, at least one gelling agent, and an aerosol former. Preferably, the gel composition is substantially tobacco-free.

[0148] The preferred weight ranges of nicotine in the gel composition are the same as those defined above in connection with the aerosol-generating film.

[0149] The gel composition preferably comprises at least 50 weight percent aerosol former, more preferably at least 60 weight percent, more preferably at least 70 weight percent aerosol former, on a dry weight basis. The gel composition may comprise up to 80 weight percent aerosol former. The aerosol former in the gel composition is preferably glycerol.

[0150] The gel composition preferably includes at least one gelling agent in a total amount ranging from about 0.4 weight percent to about 10 weight percent, or from about 0.5 weight percent to about 8 weight percent, or from about 1 weight percent to about 6 weight percent, or from about 2 weight percent to about 4 weight percent, or from about 2 weight percent to about 3 weight percent.

[0151] The term "gelling agent" refers to a compound that, when added in an amount of about 0.3 weight percent to a 50 weight percent water / 50 weight percent glycerol mixture, leads to the homogeneous formation of a solid medium or support matrix, leading to a gel. Gelling agents include, but are not limited to, hydrogen-bond cross-linking gelling agents and ionic cross-linking gelling agents.

[0152] The term "hydrogen-bond cross-linking gelling agent" refers to a gelling agent that forms non-covalent or physical cross-links via hydrogen bonds. The hydrogen-bond cross-linking gelling agent may include one or more of galactomannan, gelatin, agarose, konjac gum, or agar. Preferably, the hydrogen-bond cross-linking gelling agent includes agar.

[0153] The term "ionically cross-linked gelling agent" refers to a gelling agent that forms non-covalent or physical cross-links via ionic bonds. Ionically cross-linked gelling agents may include low acyl gellan, pectin, kappa carrageenan, iota carrageenan, or alginate. Preferably, the ionically cross-linked gelling agent may include low acyl gellan.

[0154] The gelling agent may include one or more biopolymers. The biopolymer may be formed of a polysaccharide. Examples of biopolymers include gellan gum (preferably native gellan gum, low acyl gellan gum, or high acyl gellan gum with low acyl gellan gum), xanthan gum, alginate (alginic acid), agar, guar gum, etc.

[0155] The gel composition may further comprise a thickener. The term "thickener" refers to a compound that, when uniformly added in an amount of 0.3 percent by weight to a 50 percent by weight water / 50 percent by weight glycerol mixture at 25 degrees Celsius, increases the viscosity and causes the mixture to remain fluid without forming a gel. The thickener may comprise one or more of xanthan gum, carboxymethylcellulose, microcrystalline cellulose, methylcellulose, gum arabic, guar gum, lambda carrageenan, or starch. Preferably, the thickener may comprise xanthan gum.

[0156] The gel composition may further comprise a divalent cation. Preferably, the divalent cation comprises calcium ions, such as calcium lactate in solution. The divalent cation may be present in the gel composition in a range of about 0.1 to about 1 weight percent, or about 0.5 weight percent.

[0157] The gel composition may further comprise an acid, which may comprise a carboxylic acid such as levulinic acid or lactic acid.

[0158] The gel composition preferably contains some water. The gel composition is more stable when the composition contains some water. Preferably, the gel composition contains about 8 weight percent to about 32 weight percent water, or about 15 weight percent to about 25 weight percent water, or about 18 weight percent to about 22 weight percent water, or about 20 weight percent water.

[0159] Preferably, when a gel composition is used, the aerosol-generating substrate comprises a porous medium filled with the gel composition, the term "porous" being used herein to refer to a material that provides a plurality of pores or openings that allow the passage of air through the material.

[0160] In certain embodiments of the present invention, the aerosol-generating article further comprises one or more elongated susceptor elements within the rod of the aerosol-generating substrate, for example, the one or more elongated susceptor elements may be disposed substantially longitudinally within the aerosol-generating rod and in thermal contact with the aerosol-generating substrate.

[0161] As used herein with respect to the present invention, the term "susceptor element" refers to a material capable of converting electromagnetic energy into heat. Eddy currents induced within the susceptor element result in heating of the susceptor element when it is located within a varying electromagnetic field. Because the susceptor element is located in thermal contact with the aerosol-generating substrate, the aerosol-generating substrate is heated by the susceptor element.

[0162] When used to refer to a susceptor element, the term "elongated" means that the susceptor element has a length dimension that is greater than its width dimension or its thickness dimension, for example, more than twice its width dimension or its thickness dimension.

[0163] The susceptor elements are longitudinally disposed within the rod of the aerosol-generating substrate. This means that the length dimension of the elongated susceptor elements is generally parallel to the longitudinal axis of the rod, for example, within ±10 degrees of the longitudinal axis of the rod. In a preferred embodiment, the elongated susceptor elements may be positioned at a radially central location within the rod or segment and extend along the longitudinal axis of the rod or segment.

[0164] The susceptor elements are preferably in the form of pins, rods, strips or blades.

[0165] The susceptor element preferably has a width of between 1 millimeter and 5 millimeters.

[0166] The susceptor element may generally have a thickness of 0.01 millimeters to 2 millimeters, for example, 0.5 millimeters to 2 millimeters. In some embodiments, the susceptor element preferably has a thickness of 10 micrometers to 500 micrometers, more preferably 10 micrometers to 100 micrometers.

[0167] Preferably, the elongate susceptor elements have a length that is the same as or shorter than the length of the aerosol-generation segment in which they are incorporated. Preferably, the elongate susceptor elements have a length that is the same as the length of the aerosol-generation segment in which they are incorporated.

[0168] The susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-generating substrate. Preferred susceptor elements include metal or carbon.

[0169] Suitable susceptor elements may include or consist of a ferromagnetic material, such as, for example, a ferromagnetic alloy, ferritic iron, or ferromagnetic steel or stainless steel. Suitable susceptor elements may be or include aluminum.

[0170] Preferably, the rod of aerosol-generating substrate is surrounded by a wrapper, which may be a paper wrapper or a non-paper wrapper.

[0171] Suitable paper wrappers for use in certain embodiments of the present invention are known in the art and include, but are not limited to, cigarette paper and filter plug wrap. Suitable non-paper wrappers for use in certain embodiments of the present invention are known in the art and include, but are not limited to, sheets of homogenized tobacco material.

[0172] The aerosol-generating article of the aerosol-generating system according to the present invention preferably further comprises a downstream section located downstream of the rod of the aerosol-generating substrate. The downstream section is preferably located immediately downstream of the rod of the aerosol-generating substrate. The downstream section of the aerosol-generating article preferably extends between the rod of the aerosol-generating substrate and the downstream end of the aerosol-generating article. The downstream section may comprise one or more elements, each of which is described in more detail within this disclosure.

[0173] The length of the downstream section may be between 20 mm and 70 mm, or between 25 mm and 60 mm, or between 30 mm and 50 mm.

[0174] The downstream section preferably comprises a hollow tubular cooling element provided downstream of the rod of aerosol-generating substrate, which may advantageously provide an aerosol cooling element for the aerosol-generating article.

[0175] The hollow tubular cooling element may be provided immediately downstream of the rod of the aerosol-generating substrate. In other words, the hollow tubular cooling element may abut the downstream end of the rod of the aerosol-generating substrate. The hollow tubular cooling element may define the upstream end of the downstream section of the aerosol-generating article. The downstream end of the aerosol-generating article may coincide with the downstream end of the downstream section. In some embodiments, the downstream section of the aerosol-generating article comprises a single hollow tubular element. In other words, the downstream section of the aerosol-generating article may comprise only one hollow tubular element. In other embodiments, the downstream section comprises two or more hollow tubular elements, as described below.

[0176] As used throughout this disclosure, the term "hollow tubular element" means a generally elongated element that defines a lumen or airflow passageway along its longitudinal axis.

[0177] In the context of the present invention, a hollow tubular cooling element provides an unrestricted flow channel. This means that the hollow tubular cooling element provides a negligible resistance to withdrawal (RTD). The term "negligible RTD" is used to indicate an RTD of less than 1 millimeter of HO per 10 millimeters of hollow tubular cooling element length, preferably less than 0.4 millimeters of HO per 10 millimeters of hollow tubular cooling element length, and more preferably less than 0.1 millimeters of HO per 10 millimeters of hollow tubular cooling element length.

[0178] The RTD of the hollow tubular cooling element is preferably 10 millimeters HO or less, or 5 millimeters HO or less, or 2.5 millimeters HO or less, or 2 millimeters HO or less, or 1 millimeter HO or less. The RTD of the hollow tubular cooling element can be at least 0 millimeters HO, or at least 0.25 millimeters HO, or at least 0.5 millimeters HO, or at least 1 millimeter HO.

[0179] Therefore, the flow channels should not include any components that would obstruct the longitudinal air flow. Preferably, the flow channels are substantially empty, and it is particularly preferred that the flow channels are empty.

[0180] The aerosol-generating article may include a ventilation zone located along the downstream section. In some embodiments, the aerosol-generating article may include a ventilation zone located along the hollow tubular cooling element. Such a ventilation zone, or any ventilation zone, may extend through the peripheral wall of the hollow tubular cooling element. Thus, fluid communication is established between the flow channel defined internally by the hollow tubular cooling element and the external environment. Ventilation zones are described further within this disclosure.

[0181] The length of the hollow tubular cooling element may be between 15 mm and 50 mm, or between 20 mm and 45 mm, or between 20 mm and 40 mm, or between 20 mm and 30 mm, or between 25 mm and 40 mm, or between 30 mm and 40 mm.

[0182] The wall thickness of the hollow tubular cooling element may be between 100 micrometers and 2 millimeters, or between 150 micrometers and 1.5 millimeters, or between 200 micrometers and 1.25 millimeters.

[0183] The hollow tubular cooling element preferably has an outer diameter approximately equal to the outer diameter of the rod of the aerosol-generating substrate and the outer diameter of the aerosol-generating article.

[0184] Preferably, the outer diameter of the hollow tubular cooling element is between 5 and 12 millimeters, more preferably between 6 and 10 millimeters, more preferably between 7 and 8 millimeters. In some embodiments, the outer diameter of the hollow tubular cooling element is less than 7 millimeters, for example, between 5 and 7 millimeters, or between 6 and 7 millimeters.

[0185] Preferably, the hollow tubular cooling element may have a constant inner diameter along the length of the hollow tubular cooling element. However, the inner diameter of the hollow tubular cooling element may vary along the length of the hollow tubular cooling element.

[0186] The hollow tubular cooling element may have an inner diameter of at least 2 millimeters. For example, the hollow tubular cooling element may have an inner diameter of at least 3 millimeters, at least 4 millimeters, or at least 5 millimeters.

[0187] The hollow tubular cooling element may have an inner diameter of 10 millimeters or less. For example, the hollow tubular cooling element may have an inner diameter of 9 millimeters or less, 8 millimeters or less, or 7 millimeters or less.

[0188] The hollow tubular cooling element may have an inner diameter of 2 millimeters to 10 millimeters, 3 millimeters to 9 millimeters, 4 millimeters to 8 millimeters, or 5 millimeters to 7 millimeters.

[0189] The lumen or cavity of the hollow tubular cooling element may have any cross-sectional shape. The lumen of the hollow tubular cooling element may have a circular cross-sectional shape.

[0190] The hollow tubular cooling element may comprise a paper-based material. The hollow tubular cooling element may comprise at least one layer of paper. The paper may be a very stiff paper. The paper may be a crimped paper, such as crimped heat-resistant paper or crimped parchment paper.

[0191] Preferably, the hollow tubular cooling element may comprise cardboard. The hollow tubular cooling element may be a cardboard tube. The hollow tubular cooling element may be formed from cardboard.

[0192] The hollow tubular cooling element can be a paper tube. The hollow tubular cooling element can be a tube formed from spirally wound paper. The hollow tubular cooling element can be formed from multiple layers of paper. The paper can have a basis weight of at least 50 grams per square meter, at least 60 grams per square meter, at least 70 grams per square meter, or at least 90 grams per square meter.

[0193] The hollow tubular cooling element may comprise a polymeric material. For example, the hollow tubular cooling element may comprise a polymeric film. The polymeric film may comprise a cellulose film. The hollow tubular cooling element may comprise low density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibers. The hollow tube may comprise cellulose acetate tow.

[0194] When the hollow tubular cooling element comprises cellulose acetate tow, the cellulose acetate tow can have a denier per filament of 2 to 4 and a total denier of 25,000 to 40,000.

[0195] In some embodiments, the aerosol-generating article of an aerosol-generating system according to the present invention may include a ventilation zone along the downstream section. More particularly, in those embodiments in which the downstream section comprises a hollow tubular cooling element, a ventilation zone may be provided along the hollow tubular cooling element.

[0196] The ventilation zone typically comprises a plurality of perforations through the peripheral wall of the hollow tubular cooling element. Preferably, the ventilation zone comprises at least one circumferential row of perforations. In some embodiments, the ventilation zone may comprise two circumferential rows of perforations. For example, the perforations may be formed online during the manufacture of the aerosol-generating article. Preferably, each circumferential row of perforations comprises between 8 and 30 perforations.

[0197] The aerosol-generating article of the aerosol-generating system of the present invention may have a breathability level of at least 25 percent.

[0198] The term "ventilation level" is used throughout this specification to mean the volume ratio of the airflow entering the aerosol-generating article via the ventilation zone (ventilation airflow) to the sum of the aerosol airflow and the ventilation airflow. The greater the ventilation level, the greater the dilution of the aerosol stream delivered to the consumer. The aerosol-generating article preferably has a ventilation level of at least 25 percent, more preferably at least 30 percent, even more preferably at least 40 percent, and even more preferably at least 50 percent.

[0199] The aerosol-generating articles of the aerosol-generating systems of the present invention may have a breathability level of up to 90 percent. Preferably, the aerosol-generating articles of the present invention have a breathability level of 80 percent or less, more preferably 70 percent or less, and even more preferably 60 percent or less.

[0200] For example, the aerosol-generating article of the aerosol-generating system of the present invention may have a breathability level of between 25 percent and 90 percent, preferably between 30 percent and 80 percent, more preferably between 40 percent and 70 percent, and even more preferably between 50 percent and 60 percent.

[0201] The downstream section may further include a downstream filter segment. The downstream filter segment may extend to a downstream end of the downstream section. The downstream filter segment may be located at the downstream end of the aerosol-generating article. The downstream end of the downstream filter segment may define the downstream end of the aerosol-generating article.

[0202] The downstream filter segment may be located downstream of the hollow tubular cooling element, as described above, and may extend between the hollow tubular cooling element and the downstream end of the aerosol-generating article.

[0203] The downstream filter segment is preferably a solid plug, which may also be described as a "plain" plug, and is non-tubular. Thus, the filter segment preferably has a substantially uniform cross-section.

[0204] The downstream filter segment is preferably formed of a fibrous filter material. The fibrous filter material may be for filtering the aerosol generated from the aerosol-generating substrate. Suitable fibrous filter materials will be known to those skilled in the art. Particularly preferably, at least one downstream filter segment comprises a cellulose acetate filter segment formed from cellulose acetate tow.

[0205] In certain preferred embodiments, the downstream section comprises a single downstream filter segment. In alternative embodiments, the downstream section comprises two or more downstream filter segments axially aligned in end-to-end abutting relationship with one another.

[0206] The downstream filter segment preferably has a low particle filtration efficiency.

[0207] The downstream filter segment is preferably surrounded by plug wrap. The downstream filter segment is preferably non-vented so that air does not enter the aerosol-generating article along the downstream filter segment.

[0208] The downstream filter segment is preferably connected to one or more of the adjacent upstream components of the aerosol-generating article by a tipping wrapper.

[0209] The downstream filter segment preferably has an outer diameter of 5 to 12 millimeters, more preferably 6 to 10 millimeters, and more preferably 7 to 8 millimeters. In some embodiments, the outer diameter of the downstream filter segment may be less than 7 millimeters, for example, 5 to 7 millimeters, or 6 to 7 millimeters.

[0210] As described above, the downstream filter segment may be formed of a fibrous filtration material. The downstream filter segment may be formed of a porous material. The downstream filter segment may be formed of a biodegradable material. The downstream filter segment may be formed of a cellulosic material, such as cellulose acetate.

[0211] The downstream filter segment may be formed from a polylactic acid-based material. The downstream filter segment may be formed from a bioplastic material, preferably a starch-based bioplastic material. The downstream filter segment may be made by injection molding or extrusion.

[0212] The length of the downstream filter segment may be between 5 millimeters and 25 millimeters, or between 10 millimeters and 25 millimeters, or between 5 millimeters and 20 millimeters, or between 10 millimeters and 20 millimeters.

[0213] The downstream section may further comprise one or more additional hollow tubular elements.

[0214] In certain embodiments, the downstream section may comprise a hollow tubular support element upstream of the hollow tubular cooling element described above. Preferably, the hollow tubular support element abuts the downstream end of the rod of the aerosol-generating substrate. Preferably, the hollow tubular support element abuts the upstream end of the hollow tubular cooling element. Preferably, the hollow tubular support element and the hollow tubular cooling element are adjacent to each other and together provide a hollow tubular section within the downstream section.

[0215] Preferably, the hollow tubular support element is compressible.

[0216] The hollow tubular support element may be formed from any suitable material or combination of materials. For example, the support element may be formed from one or more materials selected from the group consisting of cellulose acetate, cardboard, crimped paper (such as crimped heat-resistant paper or crimped parchment paper), and polymeric materials (such as low-density polyethylene (LDPE)). In a preferred embodiment, the support element is formed from cellulose acetate. Other suitable materials include polyhydroxyalkanoate (PHA) fibers. In a preferred embodiment, the hollow tubular support element comprises a hollow acetate tube.

[0217] The hollow tubular support element preferably has an outer diameter that is approximately equal to the outer diameter of the rod of the aerosol-generating substrate and the outer diameter of the aerosol-generating article.

[0218] Preferably, the outer diameter of the hollow tubular support element is between 5 and 12 millimeters, more preferably between 6 and 10 millimeters, and more preferably between 7 and 8 millimeters. In some embodiments, the outer diameter of the hollow tubular support element can be less than 7 millimeters, for example, between 5 and 7 millimeters, or between 6 and 7 millimeters.

[0219] The hollow tubular support element may have a wall thickness of at least 1 millimeter, preferably at least 1.5 millimeters, more preferably at least 2 millimeters.

[0220] The hollow tubular support element may have a length of 5 to 15 millimeters, preferably 6 to 15 millimeters, and more preferably 7 to 15 millimeters. In other embodiments, the support element has a length of 5 to 12 millimeters, preferably 6 to 12 millimeters, and more preferably 7 to 12 millimeters. In further embodiments, the support element has a length of 5 to 10 millimeters, preferably 6 to 10 millimeters, and more preferably 7 to 10 millimeters.

[0221] Preferably, the hollow tubular support element is adapted to be as compressible as the rod of aerosol-generating substrate, thereby allowing at least the upstream portion of the hollow tubular support element to be compressible for insertion of the aerosol-generating article into the heating device. Partial compression of the hollow tubular support element may be necessary in aerosol-generating systems in which the rod of aerosol-generating substrate is fully received within the heating chamber, and the upstream end of the hollow tubular segment may also be received within the heating chamber.

[0222] Preferably, the hollow tubular support element has a peripheral wall having a density of less than 200 mg per cubic centimeter, more preferably less than 175 mg per cubic centimeter, more preferably less than 150 mg per cubic centimeter, more preferably less than 140 mg per cubic centimeter, more preferably less than 130 mg per cubic centimeter.

[0223] As an alternative or in addition to the hollow tubular support element, the downstream section may further comprise a downstream hollow tubular element downstream of the hollow tubular cooling element.

[0224] After insertion of the aerosol-generating article into the aerosol-generating device, the overall RTD of the aerosol-generating article is preferably at least 10 millimeters HO, more preferably at least 15 millimeters HO, more preferably at least 20 millimeters HO, more preferably at least 25 millimeters HO, more preferably at least 30 millimeters HO.

[0225] After insertion of the aerosol-generating article into the aerosol-generating device, the overall RTD of the aerosol-generating article is preferably 70 millimeters HO or less, more preferably 60 millimeters HO or less, more preferably 55 millimeters HO or less, more preferably 50 millimeters HO or less, more preferably 45 millimeters HO or less.

[0226] For example, after insertion of the aerosol-generating article into an aerosol-generating device, the overall RTD of the aerosol-generating article may be between 10 millimeters HO and 70 millimeters HO, or between 15 millimeters HO and 60 millimeters HO, or between 20 millimeters HO and 55 millimeters HO, or between 25 millimeters HO and 45 millimeters HO, or between 30 millimeters HO and 45 millimeters HO.

[0227] The aerosol-generating article preferably has a total length of 40 millimeters to 80 millimeters, or 40 millimeters to about 70 millimeters, or 40 millimeters to about 60 millimeters, or 45 millimeters to about 80 millimeters, or about 45 millimeters to about 70 millimeters, or 45 millimeters to 60 millimeters, or 50 millimeters to 80 millimeters, or 50 millimeters to about 70 millimeters, or about 50 millimeters to about 60 millimeters. In an exemplary embodiment, the total length of the aerosol-generating article is about 45 millimeters.

[0228] The aerosol-generating article preferably has an outer diameter of from 5 mm to 12 mm, or from 6 mm to 12 mm, or from 7 mm to 12 mm, or from 5 mm to 10 mm, or from 6 mm to 10 mm, or from 7 mm to 10 mm, or from 5 mm to 8 mm, or from 6 mm to 8 mm, or from 7 mm to 8 mm. In other embodiments, the aerosol-generating article has an outer diameter of less than 7 mm.

[0229] The outer diameter of the aerosol-generating article may be substantially constant along the entire length of the article before insertion of the aerosol-generating article into the aerosol-generating device. Alternatively, different portions of the aerosol-generating article may have different outer diameters. In particular, the rod of the aerosol-generating substrate may have different outer diameters after insertion of the aerosol-generating article into the aerosol-generating device.

[0230] In a particularly preferred embodiment, one or more of the components of the aerosol-generating article are individually enclosed by their own wrapper.

[0231] Preferably, at least one of the components of the aerosol-generating article is packaged in a hydrophobic wrapper.

[0232] The term "hydrophobic" refers to a surface that exhibits water-repellent properties. One useful way to determine this is to measure the water contact angle. The "water contact angle" is the angle, traditionally measured through a liquid, where the liquid / vapor interface meets a solid surface. The water contact angle quantifies the wettability of a solid surface by a liquid via Young's equation. Hydrophobicity or water contact angle can be determined by utilizing the TAPPI T558 test method, with results expressed as interfacial contact angle, reported in degrees, and can range from approximately zero to approximately 180 degrees.

[0233] In a preferred embodiment, the hydrophobic wrapper is a wrapper that includes a paper layer that has a water contact angle of about 30 degrees or greater, preferably about 35 degrees or greater, or about 40 degrees or greater, or about 45 degrees or greater.

[0234] By way of example, the paper layer may comprise PVOH (polyvinyl alcohol) or silicone. The PVOH may be applied to the paper layer as a surface coating, or the paper layer may comprise a surface treatment that includes PVOH or silicone.

[0235] According to the present invention, there is further provided an aerosol generation system comprising the aerosol-generating article according to the present invention as described above and an aerosol-generating device. The aerosol-generating device comprises a body defining a heating chamber for removably receiving at least a portion of a rod of an aerosol-generating substrate of the aerosol-generating article when the aerosol-generating article is inserted into the aerosol-generating device, and a heater assembly disposed along at least a portion of the heating chamber for heating the rod of the aerosol-generating substrate when the aerosol-generating article is received in the aerosol-generating device. According to the present invention, the heating chamber comprises a pair of opposing flat surfaces configured to receive the rod of the aerosol-generating substrate therebetween, and a heater element provided on or near at least one of the pair of opposing flat surfaces. According to the present invention, the cross-section of the heating chamber is configured, as described above, such that the rod of the aerosol-generating substrate and the upstream element are compressed after the rod of the aerosol-generating substrate is inserted into the heating chamber.

[0236] As used herein with respect to the present invention, the term "heater assembly" refers to a component of an aerosol-generating device that is responsible for heating the aerosol-generating substrate of an aerosol-generating article. As explained in more detail below, the heater assembly may directly heat the aerosol-generating substrate, which may be the case when the heater assembly includes a resistive heater. The heater assembly may indirectly heat the aerosol-generating substrate, which may be the case when the heater assembly includes an induction coil.

[0237] The heating chamber of the aerosol-generating device may include an open downstream end and a closed upstream end. In use, the upstream end of the aerosol-generating device may be inserted into the open downstream end of the heating chamber. In use, the upstream end of the aerosol-generating article may abut against the upstream end of the heating chamber. Alternatively, the upstream end of the aerosol-generating article may abut against another component within the heating chamber, preventing the aerosol-generating article from moving further upstream.

[0238] As used herein with respect to the present invention, the term "fully received" refers to the position of the aerosol-generating article when it is inserted as far as possible into the heating chamber. This may be when the upstream end of the aerosol-generating article abuts the upstream end of the heating chamber. Alternatively, this may be when the upstream end of the aerosol-generating article abuts another component within the heating chamber, preventing the aerosol-generating article from moving further upstream. When the aerosol-generating article is "fully received" within the heating chamber, a portion of the aerosol-generating article may protrude beyond the open downstream end of the aerosol-generating article. This may be, for example, when the length of the aerosol-generating article is greater than the length of the heating chamber, or when the length of the aerosol-generating article is greater than the distance between the downstream end of the heating chamber and the component within the heating chamber, to prevent the aerosol-generating article, if present, from moving further upstream.

[0239] As noted above, inserting the aerosol-generating article into the heating chamber requires that both the upstream element and the rod of aerosol-generating substrate be compressed and deformed from their initial shapes to a final shape that substantially conforms to the shape of the heating chamber. As noted above, this compression also increases the density of the upstream element and the rod of aerosol-generating substrate. Preferably, the initial and final densities of the upstream element and the rod of aerosol-generating substrate are within the ranges defined above for the aerosol-generating article.

[0240] The length of the heating chamber may be between 15 mm and 80 mm. The length of the heating chamber is preferably between 20 mm and 70 mm. The length of the heating chamber is more preferably between 25 mm and 60 mm. The length of the heating chamber is more preferably between 25 mm and 50 mm.

[0241] The length of the heating chamber may be between 25 mm and 29 mm. Preferably, the length of the heating chamber is between 25 mm and 29 mm. More preferably, the length of the heating chamber is between 26 mm and 29 mm. Even more preferably, the length of the heating chamber is 27 mm or 28 mm.

[0242] The length of the heating chamber may be the same as or longer than the length of the rod of aerosol-generating substrate. The length of the heating chamber is preferably such that, when the aerosol-generating article is fully received within the heating chamber, at least 75 percent of the rod of aerosol-generating substrate is inserted or received within the heating chamber of the device. More preferably, the length of the heating chamber is such that, when the aerosol-generating article is fully received within the heating chamber, at least 80 percent of the rod of aerosol-generating substrate is inserted or received within the heating chamber. More preferably, the length of the heating chamber is such that, when the aerosol-generating article is fully received within the heating chamber, at least 90 percent of the rod of aerosol-generating substrate is inserted or received within the heating chamber. This maximizes the length of the rod of aerosol-generating substrate along which the aerosol-generating substrate can be heated during use, thereby optimizing aerosol generation from the aerosol-generating substrate and reducing waste.

[0243] The length of the heating chamber may be such that when the aerosol-generating article is fully received within the heating chamber, the downstream section, or a portion thereof, protrudes from the heating chamber.The length of the heating chamber may be such that when the aerosol-generating article is fully received within the heating chamber, a portion of the downstream section protrudes from the heating chamber.

[0244] As defined above, the heating chamber is configured to deform or transform the rod of aerosol-generating substrate after insertion of the aerosol-generating article into the aerosol-generating device. Accordingly, the shape and size of the heating chamber are configured relative to the shape and size of the rod of aerosol-generating substrate to effect the desired deformation or transformation of the aerosol-generating substrate after insertion of the rod of aerosol-generating substrate into the heating chamber. In particular, the cross-sectional area of ​​the heating chamber is adapted such that insertion of the rod of aerosol-generating substrate into the heating chamber results in at least one of an increase in the density of the aerosol-generating substrate, a decrease in the cross-sectional area of ​​the aerosol-generating substrate, and an increase in the maximum diameter of the rod of aerosol-generating substrate.

[0245] The cross-sectional area of ​​the heating chamber is preferably smaller than the initial cross-sectional area of ​​the rod of the aerosol-generating substrate.

[0246] As defined above, the heating chamber of the aerosol-generating device of the aerosol-generating system according to the present invention comprises a pair of opposing flat surfaces configured to receive the rod of the aerosol-generating substrate. The resulting heating assembly is preferably planar. The aerosol-generating device may be flat. Preferably, the opposing flat surfaces are fixed to one another within the heating chamber. The heater assembly preferably comprises a heater element provided on or near at least one of the opposing flat surfaces. Preferably, the heater assembly comprises a heater element provided on or near each of the opposing flat surfaces so that the rod of the aerosol-generating substrate is heated from both sides. In such an arrangement, the heater assembly comprises a pair of opposing heater elements that heat the rod of the aerosol-generating substrate from opposite sides. The opposing heater elements are also preferably planar, to provide a planar heating assembly.

[0247] As used herein, the term "planar" refers to a feature that extends substantially in a two-dimensional plane. Defining the surface of a heating chamber as "planar" means that the surface of the heating chamber extends substantially in a two-dimensional plane. Thus, the surface has minimal curvature, and preferably no curvature. Using a heating chamber with opposing flat surfaces on which the heater elements are mounted increases the contact area between the heater elements and the rod of the aerosol-generating substrate, resulting in more efficient heating of the aerosol-generating substrate. The spacing between the opposing heater elements can be adjusted so that the distance between them is relatively small, allowing heat to be efficiently transferred throughout the rod of the aerosol-generating substrate.

[0248] The pair of opposing flat surfaces of the heating chamber are preferably substantially parallel to one another so that the spacing between the opposing flat surfaces is substantially the same along the length of the heating chamber, and thus the heating chamber preferably has a substantially rectangular transverse cross-section.

[0249] The average spacing between the pair of opposing flat surfaces of the heating chamber is preferably less than 5 millimeters, more preferably less than 4.5 millimeters, more preferably less than 4 millimeters, more preferably less than 3.5 millimeters, and more preferably less than 3 millimeters. The average spacing between the pair of opposing flat surfaces of the heating chamber is preferably at least 2 millimeters, more preferably at least 2.5 millimeters. Thus, the average spacing may be 2 millimeters to 5 millimeters, or 2 millimeters to 4.5 millimeters, or 2 millimeters to 4 millimeters, or 2 millimeters to 3.5 millimeters, or 2 millimeters to 3 millimeters, or 2.5 millimeters to 5 millimeters, or 2.5 millimeters to 4.5 millimeters, or 2.5 millimeters to 4 millimeters, or 2.5 millimeters to 3.5 millimeters, or 2.5 millimeters to 3 millimeters.

[0250] Thus, the average spacing between a pair of opposing surfaces of the heating chamber is typically much smaller than the diameter or maximum diameter of the rod of the aerosol-generating substrate prior to insertion into the aerosol-generating device.

[0251] Preferably, the average spacing between the pair of opposing surfaces of the heating chamber is at least 1 millimeter smaller than the maximum diameter of the rod of the aerosol-generating substrate before the aerosol-generating article is inserted into the aerosol-generating device. More preferably, the spacing between the pair of opposing surfaces of the heating chamber is at least 1.5 millimeters, or at least 2 millimeters, or at least 2.5 millimeters, or at least 3 millimeters smaller than the maximum diameter of the rod of the aerosol-generating substrate before the aerosol-generating article is inserted into the aerosol-generating device. The spacing between the pair of opposing surfaces of the heating chamber may be up to 6 millimeters or up to 5 millimeters smaller than the maximum diameter of the rod of the aerosol-generating substrate before the aerosol-generating article is inserted into the aerosol-generating device.

[0252] Preferably, the ratio of the initial outer diameter of the rod of aerosol-generating substrate to the spacing between the pair of opposing surfaces of the heating chamber is at least 1.5, more preferably at least 1.75, more preferably at least 2, more preferably at least 2.25. This ratio indicates the degree of compression of the rod of aerosol-generating substrate that is required to insert it into the heating chamber.

[0253] Preferably, the heating chamber comprises a funnel-shaped portion at its open downstream end, which has a cross-sectional area that gradually decreases from the downstream end to the upstream end, which may advantageously facilitate the insertion of the rod of aerosol-generating substrate into the heating chamber, and in particular the gradual compression or flattening of the rod of aerosol-generating substrate from its initial shape to its final compressed shape.

[0254] In another preferred embodiment of the present invention, the heating chamber may comprise a pair of movable walls, at least one of which comprises a heater element on or near its inner surface. The movable walls are adapted to be movable relative to one another between an open position and a closed position. In the open position, the movable walls are spaced apart from one another so that a rod of aerosol-generating substrate can be inserted therebetween. The movable walls may then be moved toward one another to a closed position, in which the walls close around the rod of aerosol-generating substrate. Once the movable walls are closed in the closed position, the rod of aerosol-generating substrate is then held between the walls and in contact with its inner surface.

[0255] The movable wall is adapted to cause the desired compression and flattening of the rod of aerosol-generating substrate when the movable wall is closed. In such an embodiment, the rod of aerosol-generating substrate is thus compressed in a single step after inserting the aerosol-generating article into the aerosol-generating device. This may facilitate insertion of the aerosol-generating article into the aerosol-generating device and compression of the rod of aerosol-generating substrate.

[0256] Preferably, in the closed position, the movable walls may have an average spacing within the ranges indicated above for embodiments in which a pair of flat opposing surfaces are provided within the heating chamber. The aerosol generating device may be provided with means for locking the movable walls in the closed position during use, so that a desired compression level can be maintained during heating.

[0257] Preferably, the movable walls are interconnected at one end so that they form a jaw-like arrangement and can pivot relative to one another between open and closed positions, thereby optimizing the degree to which the movable walls open relative to one another to facilitate insertion of the aerosol-generating article into the aerosol-generating device.

[0258] The heater assembly may include a single heater element or multiple heater elements. Any suitable type of heater element may be used. The heater assembly may include at least one of a resistive heating element and an induction heating assembly. The heater assembly may include an external heater or external heating element.

[0259] The heater assembly may externally heat the rod of the aerosol-generating substrate when the aerosol-generating article is received within the aerosol-generating device. Such an external heater assembly may be provided on at least one side of the rod of the aerosol-generating substrate when received within the heating chamber of the aerosol-generating device. Preferably, the external heater assemblies are provided to heat opposing sides of the rod of the aerosol-generating substrate, as described above.

[0260] The heater assembly may include at least one resistive heating element. The at least one resistive heating element may be any suitable type of resistive heating element. In some embodiments, the heater assembly includes only one resistive heating element. In some embodiments, the heater assembly includes multiple resistive heating elements. The heater may include at least one resistive heating element. Preferably, the heater assembly includes multiple resistive heating elements. The resistive heating elements are preferably electrically connected in a parallel arrangement. Advantageously, providing multiple resistive heating elements electrically connected in a parallel arrangement may facilitate delivery of desired power to the heater while reducing or minimizing the voltage required to provide the desired power. Advantageously, reducing or minimizing the voltage required to operate the heater may facilitate reducing or minimizing the physical size of the power supply.

[0261] In some embodiments, the at least one heating element comprises an electrically insulating substrate and the at least one resistive heating element is provided on the electrically insulating substrate.

[0262] In some embodiments, the heater assembly comprises an induction heating assembly. The induction heating assembly may comprise an inductor coil. The aerosol generating device may comprise a power source configured to provide a high frequency oscillating current to the inductor coil.

[0263] The heater assembly may include an induction heating element. The induction heating element may be a susceptor element. In these embodiments, the susceptor element is preferably located in contact with the aerosol-generating substrate. In some embodiments, the susceptor element is located within the aerosol-generating device. In these embodiments, the susceptor element may be located within a heating chamber. The aerosol-generating device may include only one susceptor element. The aerosol-generating device may include multiple susceptor elements. In some embodiments, the susceptor element is preferably arranged to heat the outer surface of the aerosol-generating substrate.

[0264] When the heater assembly includes both an induction coil and an induction heating element, the heating zone is defined as the longitudinal space between the upstream-most portion of the induction coil and induction heating element and the downstream-most portion of the induction coil and induction heating element.

[0265] The susceptor elements may comprise any suitable material. Suitable materials for the elongated susceptor elements include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Some susceptor elements comprise metal or carbon. Advantageously, the susceptor elements may comprise or consist of ferromagnetic materials, such as, for example, ferritic iron, ferromagnetic alloys such as ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrite. Suitable susceptor elements may be or include aluminum.

[0266] As explained in more detail above, in some embodiments in which the aerosol-generating device comprises an induction coil, the aerosol-generating article may comprise at least one susceptor element.

[0267] In some embodiments, the aerosol generating device may comprise at least one resistive heating element and at least one inductive heating assembly, hi some embodiments, the aerosol generating device may comprise a combination of a resistive heating element and an inductive heating assembly.

[0268] The aerosol generating device may include an airflow channel extending between the channel inlet and the channel outlet. The airflow channel may be configured to establish fluid communication between the interior of the device cavity and the exterior of the aerosol generating device. The airflow channel of the aerosol generating device may be defined within the body of the aerosol generating device and allow fluid communication between the interior of the heating chamber and the exterior of the aerosol generating device. When an aerosol-generating article is received within the heating chamber, the airflow channel may be configured to provide airflow through the article to deliver the generated aerosol to a user who inhales through the mouth end of the article.

[0269] The aerosol generating device may include a power source. The power source may be a DC power source. In some embodiments, the power source is a battery. [Example]

[0270] The following provides a non-exhaustive list of non-limiting examples, any one or more of the features of which may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0271] Example 1 An aerosol-generating article comprising: a rod of aerosol-generating substrate; a downstream section extending from the downstream end of the rod of aerosol-generating substrate to the mouth end of the aerosol-generating article; and a compressible upstream element located upstream of the rod of aerosol-generating substrate. Example 2. 10. The aerosol-generating article of claim 1, wherein the rod of aerosol-generating substrate has a density of less than 300 mg per cubic centimeter. Example 3 3. The aerosol-generating article of claim 1 or 2, wherein the compressible upstream element has a density of less than 140 mg per cubic centimeter. Example 4. An aerosol-generating article according to any one of Examples 1 to 3, wherein the upstream element is adapted to be compressible to a final density that is at least 1.5 times the initial density. Example 5. An aerosol-generating article according to any one of Examples 1 to 4, wherein the upstream element is adapted to be compressible to a final density of at least 140 mg per cubic centimeter. Example 6 6. An aerosol-generating article according to any one of Examples 1 to 5, wherein the upstream element is formed from a fibrous filtering material. Example 7 7. The aerosol-generating article of example 6, wherein the fibrous filtration material has a denier per filament of less than 3. Example 8 8. The aerosol-generating article of any one of Examples 6 and 7, wherein the fibrous filtration material has a total denier of less than 30,000. Example 9. An aerosol-generating article according to any one of Examples 6 to 8, wherein the fibrous filtering material comprises a filter plasticizer, and the amount of filter plasticizer in the upstream element is less than 4 weight percent of the upstream element. Example 10. 10. An aerosol-generating article according to any one of Examples 1 to 9, wherein the upstream element has a withdrawal resistance of less than 25 millimeters of H2O. Example 11 An aerosol-generating article according to any one of Examples 1 to 10, wherein the upstream element has a length of between 3 millimeters and 7 millimeters. Example 12 An aerosol-generating article according to any one of Examples 1 to 11, wherein the upstream element is surrounded by a wrapper. Example 13 13. The aerosol-generating article of example 12, wherein the wrapper has a thickness of less than 40 microns. Example 14. 14. The aerosol-generating article of claim 12 or 13, wherein the wrapper has a basis weight of less than 25 grams per square meter. Example 15. An aerosol-generating article according to any one of Examples 1 to 14, wherein the density of the rods of the aerosol-generating substrate is less than 125 mg per cubic centimeter. Example 16. An aerosol-generating article according to any one of Examples 1 to 15, wherein the rod of aerosol-generating substrate is adapted to be compressible to a final density that is at least 1.1 times its initial density. Example 17. An aerosol-generating article according to any one of Examples 1 to 16, wherein the rod of aerosol-generating substrate is adapted to be compressible to a final density of at least 300 mg per cubic centimeter. Example 18. An aerosol-generating article according to any one of Examples 1 to 17, wherein the rod of the aerosol-generating substrate has a density 0.8 to 1.2 times that of the upstream element. Example 19. 19. The aerosol-generating article of Example 18, wherein the density of the rod of the aerosol-generating substrate is substantially the same as the density of the upstream element. Example 20. An aerosol-generating article according to any one of Examples 1 to 19, wherein the rod of aerosol-generating substrate has a substantially circular transverse cross-section prior to insertion of the aerosol-generating article into an aerosol-generating device. Example 22. An aerosol-generating article according to any one of Examples 1 to 20, wherein the rod of the aerosol-generating substrate has a length of 10 mm to 14 mm. Example 23. 23. The aerosol-generating article of any one of Examples 1 to 22, wherein the aerosol-generating substrate comprises at least 15 weight percent of an aerosol former. Example 24. 24. The aerosol-generating article of any one of Examples 1 to 23, wherein the aerosol-generating substrate comprises at least 40 weight percent aerosol formers. Example 25. An aerosol-generating article according to any one of Examples 1 to 24, wherein the aerosol-generating substrate does not substantially contain tobacco. Example 26. An aerosol-generating article according to any one of Examples 1 to 24, wherein the aerosol-generating substrate comprises homogenized tobacco material. Example 27. The aerosol-generating article according to any one of Examples 1 to 24, wherein the aerosol-generating substrate comprises a cut filler. Example 28. 26. The aerosol-generating article of any one of Examples 1 to 25, wherein the aerosol-generating substrate comprises an aerosol-generating film comprising a cellulosic film-forming agent, nicotine, and an aerosol former. Example 29. 26. An aerosol-generating article according to any one of Examples 1 to 25, wherein the aerosol-generating substrate comprises a gel composition comprising nicotine, at least one gelling agent, and an aerosol former. Example 30. 30. The aerosol-generating article of Example 29, wherein the gel composition is loaded onto a porous medium. Example 31. An aerosol-generating article according to any one of Examples 1 to 30, further comprising one or more elongated susceptor elements within the rod of the aerosol-generating substrate. Example 32. An aerosol-generating article according to any one of Examples 1 to 31, further comprising a downstream section located downstream of the rod of the aerosol-generating substrate. Example 33. 33. The aerosol-generating article of Example 32, wherein the downstream section comprises a compressible hollow tubular support element. Example 34. 34. An aerosol-generating article as described in Example 32 or 33, wherein the hollow tubular support element has a peripheral wall with a density of less than 140 mg per cubic centimeter. Example 35. An aerosol-generating article according to any one of Examples 32 to 34, wherein the downstream section further comprises a hollow tubular cooling element. Example 36. 36. The aerosol-generating article of Example 35, further comprising a ventilation zone located along the hollow tubular cooling element. Example 37. An aerosol-generating article according to any one of Examples 32 to 36, wherein the downstream section further comprises a downstream filter segment. Example 38. An aerosol-generating article according to any one of Examples 1 to 37, wherein the overall RTD of the aerosol-generating article is at least 25 millimeters HO. Example 39. An aerosol-generating article according to any one of Examples 1 to 38, wherein the rod of aerosol-generating substrate has a density of less than 200 mg per cubic centimeter. Example 40. 40. An aerosol-generating article according to any one of Examples 1 to 39, wherein the upstream element has a density of less than 125 mg per cubic centimeter. Example 41. An aerosol-generating article according to any one of Examples 1 to 40, further comprising an outer wrapper. Example 42. 42. The aerosol-generating article of example 41, wherein the outer wrapper has a thickness of less than 65 microns. Example 43. 43. The aerosol-generating article of claim 41 or 42, wherein the outer wrapper has a basis weight of less than 45 grams per square meter. Example 44. An aerosol generating system comprising the aerosol-generating article according to any one of Examples 1 to 43 and an aerosol generating device. Example 45. An aerosol generating system as described in Example 44, wherein the aerosol generating device comprises: a body defining a heating chamber for removably receiving at least a portion of the rod of the aerosol-generating substrate of the aerosol-generating article when the aerosol-generating article is inserted into the aerosol generating device; and a heater assembly arranged along at least a portion of the heating chamber for heating the rod of the aerosol-generating substrate when the aerosol-generating article is received in the aerosol generating device. Example 46. An aerosol generating system as described in Example 45, wherein the heating chamber comprises a pair of opposing flat surfaces configured to receive a rod of the aerosol generating substrate therebetween, and a heater element provided on or near at least one of the pair of opposing flat surfaces. Example 47. 47. The aerosol generation system of Example 46, wherein the pair of opposing flat surfaces of the heating chamber are substantially parallel to each other. Example 48. An aerosol generation system as described in Example 46 or 47, wherein the average distance between a pair of opposing flat surfaces of the heating chamber is less than 5 millimeters. Example 49. An aerosol generating system described in any of Examples 46 to 48, wherein the average spacing between a pair of opposing surfaces of the heating chamber is at least 1 millimeter smaller than the maximum diameter of the rod of the aerosol-generating substrate before insertion of the aerosol-generating article into the aerosol-generating device. Example 50. 50. An aerosol-generating article according to any one of Examples 46 to 49, wherein the ratio of the initial diameter of the rod of the aerosol-generating substrate to the spacing between the pair of opposing surfaces of the heating chamber is at least 1.5. Example 51. An aerosol generation system according to any one of Examples 46 to 50, wherein the cross section of the heating chamber is configured such that after insertion of the rod of the aerosol-generating substrate into the heating chamber, the rod of the aerosol-generating substrate and the upstream element are compressed. Example 52. 52. The aerosol-generating system of Example 51, wherein the cross-sectional area of ​​the heating chamber is smaller than the initial cross-sectional area of ​​the rod of the aerosol-generating substrate. Example 53. An aerosol generation system described in any of Examples 45 to 52, wherein the heating chamber has a funnel-shaped portion at the open downstream end, which has a cross-sectional area that gradually decreases from the downstream end to the upstream end. Example 54. An aerosol generation system described in any of Examples 45 to 52, wherein the heating chamber includes a pair of movable walls, at least one of which has a heater element on or near its inner surface, and the movable walls are adapted to be movable relative to each other between an open position and a closed position. Example 55. An aerosol generation system described in any of Examples 45 to 54, wherein the heater assembly comprises an induction heating assembly.

Claims

1. 1. An aerosol-generating article for generating an inhalable aerosol upon heating, the article extending from an oral end to a distal end; a rod of aerosol-generating substrate having a density of less than 300 mg per cubic centimeter; a downstream section located downstream of the rod of aerosol-generating substrate and extending from the downstream end of the rod of aerosol-generating substrate to the mouth end of the aerosol-generating article; an upstream compressible element located upstream of the rod of the aerosol-generating substrate, the upstream element having a density of less than 140 mg per cubic centimeter;

2. 10. The aerosol-generating article of claim 1, wherein the upstream element comprises a segment of fibrous filtration material having a denier per filament (dpf) of less than 3.

3. 3. The aerosol-generating article of claim 2, wherein the upstream element comprises a segment of cellulose acetate tow.

4. 3. The aerosol-generating article of claim 2, wherein the fibrous filtering material includes a plasticizer, the amount of plasticizer being less than 4 percent by weight of the upstream element.

5. The aerosol-generating article of claim 1 , wherein the upstream element comprises cardboard or paper.

6. 10. The aerosol-generating article of claim 1, wherein the upstream element is a hollow tubular segment having a central longitudinal cavity extending therethrough.

7. The upstream element is 25 mmH 2 10. The aerosol-generating article of claim 1, having a resistance to withdrawal (RTD) of less than O.

8. 10. The aerosol-generating article of claim 1, wherein the upstream element is surrounded by a wrapper having a thickness of less than 35 microns.

9. 10. The aerosol-generating article of claim 1, wherein the upstream element is surrounded by a wrapper having a basis weight of less than 30 grams per square meter.

10. 2. The aerosol-generating article of claim 1, wherein the density of the aerosol-generating substrate is 0.6 to 1.4 times the density of the upstream element.

11. 2. The aerosol-generating article of claim 1, wherein the downstream section comprises a compressible hollow tubular support element abutting the downstream end of the aerosol-generating substrate rod, the hollow tubular support element having a peripheral wall with a density of less than 200 mg per cubic centimeter.

12. 10. The aerosol-generating article of claim 1, wherein the aerosol-generating substrate comprises a cut tobacco material.

13. 10. The aerosol-generating article of claim 1, wherein the aerosol-generating substrate comprises an aerosol-generating film comprising nicotine and at least one aerosol former.

14. 10. The aerosol-generating article of claim 1, further comprising an elongated susceptor element extending longitudinally through the rod of the aerosol-generating substrate.

15. 1. An aerosol generating system comprising: The aerosol-generating article of claim 1; An aerosol generating device, comprising: a body defining a heating chamber for removably receiving at least a portion of the rod of the aerosol-generating substrate of the aerosol-generating article when the aerosol-generating article is inserted into the aerosol-generating device; an aerosol-generating device comprising: a heater assembly disposed along at least a portion of the heating chamber for heating the rod of aerosol-generating substrate when the aerosol-generating article is received within the aerosol-generating device, the heating chamber comprising a pair of opposing flat surfaces configured to receive the rod of aerosol-generating substrate therebetween, at least one of the opposing flat surfaces comprising a heater element; An aerosol generation system, wherein the cross-section of the heating chamber of the aerosol-generating device is configured such that after insertion of the rod of aerosol-generating substrate into the heating chamber, the rod of aerosol-generating substrate and the upstream element are compressed.

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