An aerosol-generating article comprising a porous hollow tubular substrate element

Abstract

An aerosol-generating article (10) comprising a rod (12) of an aerosol-generating substrate and a downstream section (14) provided downstream of the rod (12) of the aerosol-generating substrate, wherein the rod (12) of the aerosol-generating substrate is formed of a homogenized tobacco material and defines a longitudinal cavity (44) providing an unrestricted flow channel through the hollow tubular substrate element (40), a hollow tubular substrate element (40) surrounding the hollow tubular substrate element (40), and an outer wrapper (60) disposed such that an empty space (90) is defined between at least a portion of the outer surface of the hollow tubular substrate element (40) and the outer wrapper, the hollow tubular substrate element (40) comprising a plurality of perforations (46) providing fluid communication between the longitudinal cavity (44) of the hollow tubular substrate element (40) and the empty space (90) between at least a portion of the outer surface of the hollow tubular substrate element (40) and the outer wrapper (60), the plurality of perforations (46) of the hollow tubular substrate element (40) being formed through the peripheral wall of the hollow tubular substrate element (40), and the outer wrapper (60) comprising a plurality of perforations (66) overlying the hollow tubular substrate element (40).

Description

Technical Field

[0001] The present invention relates to an aerosol generating article comprising a rod of an aerosol generating substrate adapted to generate an inhalable aerosol upon heating.

Background Art

[0002] Aerosol generating articles in which an aerosol generating substrate such as a tobacco-containing substrate is heated rather than burned 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 in contact with the heat source, within the heat source, around the heat source, 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 entrained in the air drawn through the aerosol generating article. The released compounds condense as they cool 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 electrical heater elements of the aerosol generating device to the aerosol generating substrate of a heated aerosol generating article. For example, an electrically heated aerosol generating device has been proposed that comprises an internal heater blade adapted to be inserted into an aerosol generating substrate. It is also well known to use an aerosol generating article in combination with an external heating system. For example, International Application No. WO-A-2020 / 115151 describes the provision of an external heating element disposed around the perimeter of an aerosol generating article when the aerosol generating article is received within a cavity of an aerosol generating device. Alternatively, an inductively heatable aerosol generating article comprising an aerosol generating substrate and a susceptor disposed within the aerosol generating substrate has been proposed by International Application No. WO-A-2015 / 176898.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, it can be difficult to provide efficient heating of an aerosol generating substrate across the entire rod of the substrate. While the portion of the substrate closest to the heating element is necessarily heated most effectively, if heat transfer is incomplete through the substrate, it means that the portion of the substrate farthest from the heating element may not be heated effectively. Thus, aerosol generation from these portions of the substrate that are not effectively heated is not optimal, and in some cases, portions of the substrate may not reach a temperature high enough to generate aerosol during use. For example, when an external heating element is used to heat the rod of an aerosol generating substrate as described above, the central portion of the rod of the aerosol generating substrate is less likely to generate as much aerosol as the outer portion of the rod, and in some cases, may not generate any aerosol at all. Thus, overall, aerosol generation from the aerosol generating rod can be inefficient, and a portion of the aerosol generating substrate is potentially wasted.

[0005] In addition, the aerosol is generally not immediately generated by the aerosol generating substrate when the heating element is activated. This is because there is a preheating time after activation of the heating element, during which the aerosol generating substrate is heated to the temperature required for aerosol generation. Thus, there can be a relatively long duration between activation of the heating element and the generation of an aerosol that is sensibly acceptable for inhalation by the user.

[0006] Accordingly, it is desirable to provide an aerosol generating article having an aerosol generating substrate that is adapted to provide more efficient aerosolization of the aerosol generating substrate and reduce waste of substrate materials such as tobacco. It is also desirable to provide such an aerosol generating article that can achieve a relatively short preheating time, such that a sensorily acceptable aerosol can be delivered to the user immediately after the start of heating of the aerosol generating substrate. It would be desirable to provide such an aerosol generating article that can provide optimized delivery of the aerosol from the aerosol generating substrate. It would be particularly desirable to provide such an aerosol generating article in a relatively simple design that can be manufactured in a cost-effective manner and incorporated into existing product designs. It would be further desirable to provide such an article that can be easily adapted to be heated by various types of heating devices, including induction heating devices and resistive heating devices.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0008] The present disclosure relates to aerosol generating articles. The aerosol generating article may comprise a rod of an aerosol generating substrate. The aerosol generating article may comprise a downstream section provided downstream of the rod of the aerosol generating substrate. The rod of the aerosol generating substrate may comprise a hollow tubular substrate element. The hollow tubular substrate element may be formed of a homogenized tobacco material. The hollow tubular substrate element may define a longitudinal cavity providing an unrestricted flow path through the hollow tubular substrate element. The aerosol generating substrate may comprise an outer wrapper surrounding the hollow tubular substrate element. The outer wrapper may be arranged such that an empty space is defined between at least a portion of the outer surface of the hollow tubular substrate element and the outer wrapper. The hollow tubular substrate element may comprise a plurality of perforations. The plurality of perforations may provide fluid communication between the longitudinal cavity of the hollow tubular substrate element and the empty space between at least a portion of the outer surface of the hollow tubular substrate element and the outer wrapper.

[0009] According to the present invention, there is provided an aerosol generating article comprising a rod of an aerosol generating substrate and a downstream section provided downstream of the rod of the aerosol generating substrate, wherein the rod of the aerosol generating substrate is formed of a homogenized tobacco material and defines a longitudinal cavity providing an unrestricted flow channel through the hollow tubular substrate element, an outer wrapper surrounding the hollow tubular substrate element and arranged such that an empty space is defined between at least a portion of the outer surface of the hollow tubular substrate element and the outer wrapper, and the hollow tubular substrate element comprises a plurality of perforations providing fluid communication between the longitudinal cavity of the hollow tubular substrate element and the empty space between at least a portion of the outer surface of the hollow tubular substrate element and the outer wrapper.

[0010] As used herein in the context of the present invention, the term "aerosol generating article" is used to describe an article comprising an aerosol generating substrate that generates an inhalable aerosol upon heating and delivers it to a user.

[0011] As used herein in connection with the present invention, the term "aerosol generating substrate" is used to describe a substrate that includes an aerosol generating material having the ability to release a volatile compound that can generate an aerosol upon heating.

[0012] As used herein in connection with the present invention, the term "aerosol" is used to describe a dispersion of solid particles, or droplets, or a combination of solid particles and droplets in a gas. The aerosol may be visible or invisible. The aerosol may include not only vapors of substances that are normally liquid or solid at room temperature, but also solid particles or liquid droplets, or a combination of solid particles and liquid droplets.

[0013] As used herein in connection with the present invention, the term "rod" is used to denote a generally cylindrical element having a substantially circular, oval or elliptical cross-section.

[0014] The aerosol generating article according to the present invention has a downstream end through which the aerosol exits the aerosol generating article for delivery to the user during use. The downstream end of the aerosol generating article may also be referred to as the proximal end or the mouth-side end of the aerosol generating article. During use, the user directly or indirectly inhales the downstream end of the aerosol generating article to inhale the aerosol generated by the aerosol generating article.

[0015] The aerosol generating article according to the present invention has an upstream end. The upstream end is opposite to the downstream end. The upstream end of the aerosol generating article may also be referred to as the distal end of the aerosol generating article.

[0016] The components of the aerosol generating article according to the present invention may be described as being upstream or downstream of each other based on their relative positions between the upstream end and the downstream end of the aerosol generating article.

[0017] As used herein in connection with the present invention, the term "longitudinal direction" refers to the direction between the upstream end and the downstream end of the aerosol generating article facing it.

[0018] As used herein in connection with the present invention, the term "transverse direction" is used to describe a direction perpendicular to the major axis direction.

[0019] As used herein in connection with the present invention, the term "cross-section" is used to refer to the cross-section of the aerosol generating article or its components, unless otherwise specified.

[0020] As used herein in connection with the present invention, the terms "hollow tubular element" and "hollow tubular substrate element" refer to generally elongated elements that define a lumen or air flow passage along their longitudinal axis. In particular, the term "tubular" is used with respect to a tubular element that has a substantially cylindrical cross-section and defines at least one air flow conduit that establishes unbroken fluid communication between the upstream end and the downstream end of the tubular element. However, of course, alternative shapes of the tubular element (e.g., alternative cross-sectional shapes) may be possible. The hollow tubular element can be an individual, separate element of the aerosol generating article having a defined length and thickness.

[0021] As used herein in connection with the present invention, the term "homogenized tobacco material" encompasses any material formed by the aggregation of tobacco particles. The homogenized tobacco material may be produced by casting, extrusion, papermaking processes, or any other suitable process known in the art.

[0022] Regarding the present invention, as used herein, the term "tobacco particle" refers to particles of any plant member of the Nicotiana species. The term "tobacco particle" includes ground or powdered tobacco leaf lamina, ground or powdered tobacco leaf stalks, tobacco dust, tobacco fines, and other particulate tobacco by-products formed during the processing, handling, and shipping of tobacco. Preferably, substantially all of the tobacco particles are derived from tobacco leaf lamina. In contrast, isolated nicotine and nicotine salts, while being compounds derived from tobacco, are not considered tobacco particles for the purposes of the present invention.

[0023] As described above, the present invention provides a hollow tubular substrate element and an outer wrapper that surrounds the hollow tubular substrate element and is arranged such that an empty space is defined between at least a portion of the outer surface of the hollow tubular substrate element and the outer wrapper. Thus, the empty space is located outside the hollow tubular substrate element.

[0024] Providing a hollow tubular substrate element that defines a cavity in the longitudinal axis direction, an empty space located outside the hollow tubular substrate element, and a plurality of perforations through the wall of the hollow tubular substrate element that provide fluid communication between the cavity in the longitudinal axis direction and the empty space advantageously enables the generation of an aerosol and its release from both the inner and outer surfaces of the hollow tubular substrate element. The aerosol released from the outer surface of the hollow tubular substrate element into the empty space may be drawn through the plurality of perforations into the cavity in the longitudinal axis direction of the hollow tubular substrate element when the consumer inhales on the aerosol-generating article. This advantageously may increase the amount of aerosol generated from the aerosol-generating substrate per puff. Thereby, when heating of the aerosol-generating substrate is initiated, it becomes possible to more rapidly generate a sensibly acceptable aerosol. Thus, this may shorten the preheating time of the aerosol-generating article. In particular, when the aerosol-generating substrate is heated by an external heating means, since the outer surface of the hollow tubular substrate element is in proximity to the external heating means, a sensibly acceptable aerosol may be generated more rapidly.

[0025] Furthermore, the provision of a plurality of perforations providing fluid communication between the cavity in the longitudinal axis direction and the empty space advantageously increases, for example, the level of turbulence within the cavity in the longitudinal axis of the hollow tubular substrate element when the consumer inhales on the aerosol generating substrate. This may enhance the mixing of the air and aerosol-forming components released from the hollow tubular substrate element, thereby improving aerosol generation.

[0026] Providing a substrate element in a tubular form advantageously allows the amount of tobacco material in the aerosol generating substrate to be optimized, such that the aerosol can be efficiently generated from the aerosol generating substrate upon heating. Further, the tubular form removes the central portion of the homogenized tobacco material which may not be heated as effectively towards the outer portions, particularly in an aerosol generating device comprising external heating means. Thus, overall, the amount of tobacco material can be significantly reduced compared to a conventional solid plug of homogenized tobacco material, reducing tobacco waste. For example, the amount of tobacco material used in the hollow tubular substrate element of an aerosol generating article according to the present invention can be reduced by up to 40 percent compared to the amount of tobacco material used in the solid plug of the substrate of a conventional aerosol generating article, while still maintaining a similar delivery of aerosol to the consumer.

[0027] The amount of tobacco material supplied within the substrate can be easily adapted by controlling parameters of the hollow tubular substrate element, such as the density of the peripheral wall and the wall thickness of the hollow tubular substrate element. In this way, it is possible to adapt the hollow tubular substrate element to coincide with the heating zone of the associated aerosol generating device. Thus, the proportion of the aerosol generating substrate that can be heated to the temperature required for aerosol generation can be maximized such that the generation of aerosol from the aerosol generating substrate can be optimized.

[0028] The hollow tubular substrate element has a relatively simple structure that can be manufactured in a simple and cost-effective manner using existing equipment. Subsequently, the hollow tubular substrate element can be incorporated into an aerosol-generating article having other components using known assembly methods and equipment.

[0029] As described above, the hollow tubular substrate element is formed of a homogenized tobacco material. Preferably, the hollow tubular substrate element is formed of one or more layers of homogenized tobacco material, such as a cast leaf.

[0030] Preferably, the hollow tubular substrate element is formed of two or more overlapping layers of homogenized tobacco material, more preferably three or more overlapping layers of homogenized tobacco material.

[0031] The hollow tubular substrate element is preferably formed of overlapping layers of homogenized tobacco material within 10 layers, more preferably within 5 layers of homogenized tobacco material. For example, the hollow tubular substrate element can be formed of from about two to about 10 overlapping layers of homogenized tobacco material, or from about three to about five overlapping layers of homogenized tobacco material.

[0032] Preferably, the plurality of overlapping layers of homogenized tobacco material directly overlap each other such that adjacent layers are in direct contact with each other without an intermediate layer.

[0033] The multi-layer arrangement of the layers can provide a relatively dense structure having sufficient structural rigidity to provide an aerosol-generating substrate for an aerosol-generating article without the need for additional support such as a carrier layer or an internal support member within the longitudinal cavity.

[0034] Preferably, the homogenized tobacco material is in the form of a sheet. As used herein in connection with the present invention, the term "sheet" describes a thin, layer-like element having a width and length that are considerably greater than its thickness.

[0035] The hollow tubular substrate element can have a length of at least about 5 millimeters, or at least about 7 millimeters, or at least about 10 millimeters.

[0036] The hollow tubular substrate element can have a length of up to about 30 millimeters, up to about 25 millimeters, or up to about 20 millimeters.

[0037] For example, the hollow tubular substrate element can have a length of from about 5 millimeters to about 30 millimeters, or from about 7 millimeters to about 25 millimeters, or from about 10 millimeters to about 20 millimeters.

[0038] Preferably, the hollow tubular substrate element has a length of about 12 millimeters.

[0039] As described above, the length of the hollow tubular substrate element can advantageously match the longitudinal dimension of the heating element in the corresponding aerosol generating device used to heat the aerosol generating article. In this way, in order to optimize the amount of aerosol that can be generated and reduce the amount of tobacco waste, the aerosol generating substrate can be heated as much as possible during use.

[0040] Preferably, the ratio of the length of the hollow tubular substrate element to the total length of the aerosol generating article can be at least about 0.1. More preferably, the ratio of the length of the hollow tubular substrate element to the total length of the aerosol generating article can be at least about 0.15. More preferably, the ratio of the length of the hollow tubular substrate element to the total length of the aerosol generating article can be at least about 0.2.

[0041] Preferably, the ratio of the length of the hollow tubular substrate element to the total length of the aerosol generating article can be at most about 0.6. More preferably, the ratio of the length of the hollow tubular substrate element to the total length of the aerosol generating article can be at most about 0.55. More preferably, the ratio of the length of the hollow tubular substrate element to the total length of the aerosol generating article can be at most about 0.5.

[0042] For example, the ratio of the length of the hollow tubular substrate element to the total length of the aerosol-generating article substrate can be from about 0.1 to about 0.6, more preferably from about 0.15 to about 0.55, and even more preferably from about 0.2 to about 0.5.

[0043] Preferably, the hollow tubular substrate element has an outer diameter that is smaller than the outer diameter of the aerosol-generating article.

[0044] Preferably, the hollow tubular substrate element can have an outer diameter of at least about 5 millimeters, or at least about 5.5 millimeters, or at least about 6 millimeters.

[0045] Preferably, the hollow tubular substrate element can have an outer diameter of at most about 9 millimeters, or at most about 8 millimeters, or at most about 7.5 millimeters.

[0046] For example, the hollow tubular substrate element can have an outer diameter from about 5 millimeters to about 9 millimeters, or from about 5.5 millimeters to about 8 millimeters, or from about 6 millimeters to about 7.5 millimeters.

[0047] Preferably, the outer diameter of the hollow tubular substrate element is substantially constant along the length of the hollow tubular substrate. Alternatively, different portions of the hollow tubular substrate element may have different outer diameters.

[0048] As used herein with respect to the present invention, the term "outer diameter" refers to the maximum diameter of the aerosol-generating article or a component thereof in the transverse direction of the aerosol-generating article at a position along the length of the aerosol-generating article or the component thereof. When a range or value of the outer diameter of the aerosol-generating article or a component thereof is described herein, the outer diameter of the aerosol-generating article or the component thereof along the entire length of the aerosol-generating article or the component thereof may be within the same range or may have the same value. In other words, when a range or value of the outer diameter of the aerosol-generating article or a component thereof is described herein, the outer diameter of the aerosol-generating article or the component thereof at all positions along the length of the aerosol-generating article or the component thereof may fall within the same range or may have the same value.

[0049] The outer diameter of the hollow tubular substrate element does not include the width of any other component of the aerosol-generating substrate located outside the hollow tubular substrate element.

[0050] The hollow tubular substrate element has a peripheral wall that defines a cavity in the longitudinal axis direction. The wall thickness of the hollow tubular substrate element may be selected based on a desired amount of tobacco material within the hollow tubular substrate. The wall thickness of the hollow tubular substrate element may also be selected such that the hollow tubular substrate element has sufficient rigidity to be self-supporting. The wall thickness of the hollow tubular substrate may also be selected such that the cavity in the longitudinal axis direction has a cross-sectional area that provides a desired draw resistance (RTD) to the hollow tubular substrate element.

[0051] The hollow tubular substrate element may have a wall thickness that is at least about 4 percent of the outer diameter of the hollow tubular substrate element, or at least about 5 percent of the outer diameter of the hollow tubular substrate element, or at least about 6 percent of the outer diameter of the hollow tubular substrate element.

[0052] The hollow tubular substrate element may have a wall thickness that is at most about 40 percent of the outer diameter of the hollow tubular substrate element, or at most about 30 percent of the outer diameter of the hollow tubular substrate element, or at most about 20 percent of the outer diameter of the hollow tubular substrate element.

[0053] For example, the hollow tubular substrate element may have a wall thickness that is about 4 percent to about 40 percent of the outer diameter of the hollow tubular substrate element, or about 5 percent to about 30 percent of the outer diameter of the hollow tubular substrate element, or about 6 percent to about 20 percent of the outer diameter of the hollow tubular substrate element.

[0054] Preferably, the hollow tubular substrate element has a wall thickness of about 7 percent of the outer diameter of the hollow tubular substrate element.

[0055] The hollow tubular substrate element may have a wall thickness of at least about 0.3 millimeters, or at least about 0.35 millimeters, or at least about 0.4 millimeters.

[0056] The hollow tubular substrate element may have a wall thickness of up to about 3 millimeters, or up to about 2 millimeters, or up to about 1 millimeter.

[0057] For example, the hollow tubular substrate element may have a wall thickness of about 0.3 millimeters to about 3 millimeters, or about 0.35 millimeters to about 2 millimeters, or about 0.4 millimeters to about 1 millimeter.

[0058] The hollow tubular substrate element may have a wall thickness of about 0.5 millimeters.

[0059] As described above, the cavity in the longitudinal axis direction provides an unrestricted flow channel through the hollow tubular substrate element. This means that the hollow tubular substrate element provides a negligible level of draw resistance (RTD). The term "negligible level of RTD" is used to represent an RTD of less than 1 mm H2O per 10 millimeters of the length of the hollow tubular substrate element, preferably less than 0.4 mm H2O per 10 millimeters of the length of the hollow tubular substrate element, and more preferably less than 0.1 mm H2O per 10 millimeters of the length of the hollow tubular substrate element.

[0060] Therefore, the cavity in the major axis direction should not include any component that would impede the air flow in the major axis direction. The cavity in the major axis direction is preferably substantially empty. More preferably, the cavity in the major axis direction is empty.

[0061] The cavity in the major axis direction may also be referred to as an air flow channel in the major axis direction.

[0062] The cavity in the major axis direction extends between both ends of the hollow tubular substrate element and is preferably open at both the upstream end and the downstream end. The open upstream end may provide a main air inlet for the consumer to draw air through the aerosol-generating article when smoking the article. The cavity in the major axis direction can thus provide a main passage for the flow of air and aerosol through the article.

[0063] The diameter of the cavity in the major axis direction corresponds to the inner diameter of the hollow tubular substrate element.

[0064] The cavity in the major axis direction can have a diameter of at least about 1 millimeter, or at least about 2 millimeters, or at least about 3 millimeters.

[0065] The cavity in the major axis direction can have a diameter of up to about 8 millimeters, or up to about 7 millimeters, or up to about 6.5 millimeters.

[0066] For example, the longitudinal cavity can have a diameter of from about 1 millimeter to about 8 millimeters, or from about 2 millimeters to about 7 millimeters, or from about 3 millimeters to about 6.5 millimeters.

[0067] The diameter of the cavity in the major axis direction may be about 6 millimeters.

[0068] The diameter of the cavity in the major axis direction may be selected such that the volume of the cavity is large enough to provide a desired level of air flow while maintaining a sufficient wall thickness. This is necessary for specifications such that a sufficient amount of tobacco material is provided within the hollow tubular substrate element and the hollow tubular substrate element has sufficient rigidity to be self-supporting.

[0069] Preferably, the cavity in the major axis direction has a substantially constant cross-sectional shape and size along the length of the hollow tubular substrate. However, one or both of the cross-sectional shape and size of the cavity in the major axis direction may vary along the length of the hollow tubular substrate element.

[0070] Preferably, the cavity in the major axis direction has a substantially circular cross-section. Alternatively, the cavity in the major axis direction may have a substantially elliptical cross-section.

[0071] The cavity in the major axis direction may have a constant diameter along the length of the hollow tubular substrate element. However, the diameter of the cavity in the major axis direction may vary along the length of the hollow tubular substrate element.

[0072] As described above, the hollow tubular substrate element includes a plurality of perforations that provide fluid communication between the cavity in the major axis direction of the hollow tubular substrate element and the empty space between at least a portion of the outer surface of the hollow tubular substrate element and the outer wrapper. The plurality of perforations are formed through the peripheral wall of the hollow tubular substrate element. The provision of the plurality of perforations may enable aerosol released into the empty space, which is generated from the outer portion of the hollow tubular substrate element and inhaled by the consumer through the aerosol-generating article, to be drawn into the cavity in the major axis direction of the hollow tubular substrate element. The provision of the plurality of perforations may increase the level of turbulent flow within the cavity in the major axis direction of the hollow tubular substrate element. This may enhance the mixing of air and aerosol-forming components released from the hollow tubular substrate element, thereby improving aerosol generation.

[0073] Preferably, the plurality of perforations are arranged in one or more circumferentially extending rows around the hollow tubular substrate element. In other words, it is preferred that the hollow tubular substrate element comprises one or more rows of perforations that extend circumferentially around the hollow tubular substrate element.

[0074] The hollow tubular substrate element may comprise at least two rows of perforations that extend circumferentially around the hollow tubular substrate element.

[0075] The hollow tubular substrate element may comprise up to five rows of perforations that extend circumferentially around the hollow tubular substrate element.

[0076] The circumferential rows of perforations may follow various patterns. For example, the circumferential rows of perforations may be arranged circularly or helically around the hollow tubular substrate element.

[0077] Preferably, each circumferential row of perforations contains from 8 to 30 perforations.

[0078] The plurality of perforations may be formed using any suitable well-known method, such as online during the manufacture of the aerosol generating article.

[0079] The plurality of perforations may include at least one perforation having a maximum dimension of at least 200 micrometers, or at least 300 micrometers, or at least about 400 micrometers, or at least about 500 micrometers.

[0080] When the perforation is substantially circular, the maximum dimension of the perforation is the diameter of the perforation. The plurality of perforations may include at least one perforation having a maximum dimension of up to about 1 millimeter, or up to about 900 micrometers, or up to about 800 micrometers, or up to about 700 micrometers.

[0081] The plurality of perforations may include at least one perforation having a maximum dimension of from about 200 micrometers to about 1 millimeter, or from about 200 micrometers to about 900 micrometers, or from about 200 micrometers to about 800 micrometers, or from about 200 micrometers to about 700 micrometers.

[0082] The plurality of perforations may include at least one perforation having a maximum dimension of from about 300 micrometers to about 1 millimeter, or from about 300 micrometers to about 900 micrometers, or from about 300 micrometers to about 800 micrometers, or from about 300 micrometers to about 700 micrometers.

[0083] The plurality of perforations may include at least one perforation having a maximum dimension of from about 400 micrometers to about 1 millimeter, or from about 400 micrometers to about 900 micrometers, or from about 400 micrometers to about 800 micrometers, or from about 400 micrometers to about 700 micrometers.

[0084] The plurality of perforations may include at least one perforation having a maximum dimension of from about 500 micrometers to about 1 millimeter, or from about 500 micrometers to about 900 micrometers, or from about 500 micrometers to about 800 micrometers, or from about 500 micrometers to about 700 micrometers.

[0085] Each of the plurality of perforations may have a maximum dimension of at least 200 micrometers, at least 300 micrometers, at least 400 micrometers, or at least 500 micrometers.

[0086] Each of the plurality of perforations may have a maximum dimension of up to about 1 millimeter, or up to about 900 micrometers, or up to about 800 micrometers, or up to about 700 micrometers.

[0087] Each of the plurality of perforations may have a maximum dimension between about 200 micrometers and about 1 millimeter, or between about 200 micrometers and about 900 micrometers, or between about 200 micrometers and about 800 micrometers, or between about 200 micrometers and about 700 micrometers.

[0088] Each of the plurality of perforations may have a maximum dimension between about 300 micrometers and about 1 millimeter, or between about 300 micrometers and about 900 micrometers, or between about 300 micrometers and about 800 micrometers, or between about 300 micrometers and about 700 micrometers.

[0089] Each of the plurality of perforations may have a maximum dimension between about 400 micrometers and about 1 millimeter, or between about 400 micrometers and about 900 micrometers, or between about 400 micrometers and about 800 micrometers, or between about 400 micrometers and about 700 micrometers.

[0090] Each of the plurality of perforations may have a maximum dimension between about 500 micrometers and about 1 millimeter, or between about 500 micrometers and about 900 micrometers, or between about 500 micrometers and about 800 micrometers, or between about 500 micrometers and about 700 micrometers.

[0091] The plurality of perforations may be composed of at least one perforation having an opening area of at least about 0.01 square millimeters, or at least about 0.03 square millimeters, or at least about 0.05 square millimeters, or at least about 0.07 square millimeters.

[0092] The plurality of perforations may include at least one perforation having an opening area of 1 square millimeter or less, or 0.8 square millimeters or less, or 0.5 square millimeters or less, or 0.3 square millimeters or less, or 0.1 square millimeters or less.

[0093] The plurality of perforation lines may include at least one perforation line having an opening area of from about 0.01 square millimeters to about 1 square millimeter, or from about 0.01 square millimeters to about 0.8 square millimeter, or from about 0.01 square millimeters to about 0.5 square millimeter, or from about 0.01 square millimeters to about 0.3 square millimeter, or from about 0.01 square millimeters to about 0.1 square millimeter.

[0094] The plurality of perforation lines can include at least one perforation line having an opening area of from about 0.03 square millimeters to about 1 square millimeter, or from about 0.03 square millimeters to about 0.8 square millimeter, or from about 0.03 square millimeters to about 0.5 square millimeter, or from about 0.03 square millimeters to about 0.3 square millimeter, or from about 0.03 square millimeters to about 0.1 square millimeter.

[0095] The plurality of perforation lines can include at least one perforation line having an opening area of from about 0.05 square millimeters to about 1 square millimeter, or from about 0.05 square millimeters to about 0.8 square millimeter, or from about 0.05 square millimeters to about 0.5 square millimeter, or from about 0.05 square millimeters to about 0.3 square millimeter, or from about 0.05 square millimeters to about 0.1 square millimeter.

[0096] The plurality of perforation lines can include at least one perforation line having an opening area of from about 0.07 square millimeters to about 1 square millimeter, or from about 0.07 square millimeters to about 0.8 square millimeter, or from about 0.07 square millimeters to about 0.5 square millimeter, or from about 0.07 square millimeters to about 0.3 square millimeter, or from about 0.07 square millimeters to about 0.1 square millimeter.

[0097] Each of the plurality of perforations may have an opening area of at least about 0.01 square millimeters, or at least about 0.03 square millimeters, or at least about 0.05 square millimeters, or at least about 0.07 square millimeters.

[0098] Each of the plurality of perforations may have an opening area of 1 square millimeter or less, or 0.8 square millimeter or less, or 0.5 square millimeter or less, or 0.3 square millimeter or less, or 0.1 square millimeter or less.

[0099] Each of the plurality of perforations may have an opening area between about 0.01 square millimeter and about 1 square millimeter, or between about 0.01 square millimeter and about 0.8 square millimeter, or between about 0.01 square millimeter and about 0.5 square millimeter, or between about 0.01 square millimeter and about 0.3 square millimeter, or between about 0.01 square millimeter and about 0.1 square millimeter.

[0100] Each of the plurality of perforations may have an opening area between about 0.03 square millimeter and about 1 square millimeter, or between about 0.03 square millimeter and about 0.8 square millimeter, or between about 0.03 square millimeter and about 0.5 square millimeter, or between about 0.03 square millimeter and about 0.3 square millimeter, or between about 0.03 square millimeter and about 0.1 square millimeter.

[0101] Each of the plurality of perforations may have an opening area between about 0.05 square millimeter and about 1 square millimeter, or between about 0.05 square millimeter and about 0.8 square millimeter, or between about 0.05 square millimeter and about 0.5 square millimeter, or between about 0.05 square millimeter and about 0.3 square millimeter, or between about 0.05 square millimeter and about 0.1 square millimeter.

[0102] Each of the plurality of perforations may have an opening area between about 0.07 square millimeter and about 1 square millimeter, or between about 0.07 square millimeter and about 0.8 square millimeter, or between about 0.07 square millimeter and about 0.5 square millimeter, or between about 0.07 square millimeter and about 0.3 square millimeter, or between about 0.07 square millimeter and about 0.1 square millimeter.

[0103] The plurality of perforations can have a total opening area of at least about 0.05 square millimeters, or at least about 0.2 square millimeters, or at least about 0.35 square millimeters, or at least about 0.5 square millimeters.

[0104] The plurality of perforations can have a total opening area of at most about 30 square millimeters, or at most about 25 square millimeters, or at most about 15 square millimeters, or at most about 10 square millimeters, or at most about 5 square millimeters.

[0105] The plurality of perforations can have a total opening area of from about 0.05 square millimeters to about 30 square millimeters, or from about 0.05 square millimeters to about 25 square millimeters, or from about 0.05 square millimeters to about 15 square millimeters, or from about 0.05 square millimeters to about 10 square millimeters, or from about 0.05 square millimeters to about 5 square millimeters.

[0106] The plurality of perforations can have a total opening area of from about 0.05 square millimeters to about 30 square millimeters, or from about 0.05 square millimeters to about 25 square millimeters, or from about 0.05 square millimeters to about 15 square millimeters, or from about 0.05 square millimeters to about 10 square millimeters, or from about 0.05 square millimeters to about 5 square millimeters.

[0107] The plurality of perforations can have a total opening area of from about 0.05 square millimeters to about 30 square millimeters, or from about 0.05 square millimeters to about 25 square millimeters, or from about 0.05 square millimeters to about 15 square millimeters, or from about 0.05 square millimeters to about 10 square millimeters, or from about 0.05 square millimeters to about 5 square millimeters.

[0108] The plurality of perforations can have a total opening area of from about 0.05 square millimeters to about 30 square millimeters, or from about 0.05 square millimeters to about 25 square millimeters, or from about 0.05 square millimeters to about 15 square millimeters, or from about 0.05 square millimeters to about 10 square millimeters, or from about 0.05 square millimeters to about 5 square millimeters.

[0109] Preferably, both the shape and size of each of the plurality of perforations are the same. This can advantageously simplify the manufacture of the plurality of perforations.

[0110] The plurality of perforations may be substantially circular. The plurality of perforations may be in the shape of a rectangle or a square.

[0111] The hollow tubular substrate element may have a ventilation level of at least about 5 percent, or at least about 10 percent, or at least about 15 percent.

[0112] The hollow tubular substrate element may have a ventilation level of up to about 60 percent, or up to about 45 percent, or up to about 30 percent.

[0113] As used herein with reference to the present invention, the term "ventilation level" is used to describe the volume ratio between the airflow entering the hollow tubular substrate element through the perforations in the wall of the hollow tubular substrate element, the sum of the airflow into the hollow tubular substrate element through the upstream end of the hollow tubular substrate element, and the airflow into the hollow tubular substrate element through the perforations in the wall of the hollow tubular substrate element. A higher ventilation level may mean that a higher proportion of the aerosol from the empty space is drawn into the hollow cavity.

[0114] The rod of the aerosol generating substrate may comprise one or more protrusions extending across the empty space between the outer surface of the hollow tubular substrate element and the outer wrapper. The one or more protrusions preferably extend from the outer surface of the hollow tubular substrate element to the inner surface of the outer wrapper. Thus, the width of the one or more protrusions is approximately the same as the width of the empty space measured in the radial direction. The width of the one or more protrusions is not taken into account when measuring the outer diameter of the hollow tubular substrate element.

[0115] As used herein with respect to the present invention, the term "radial direction" is used to denote the direction extending in a plane perpendicular to the central longitudinal axis of the aerosol generating article and passing through the point of intersection of the plane perpendicular to the central longitudinal axis. Thus, as used herein with reference to the present invention, the term "radial direction" refers to the direction perpendicular to the central longitudinal axis and is used, for example, when describing an aerosol generating article having a substantially cylindrical shape.

[0116] The outer wrapper may be wound around the one or more protrusions so as to fix the hollow tubular substrate element in place and help maintain the empty space between the hollow tubular substrate element and the outer wrapper.

[0117] The one or more protrusions may be integral with the hollow tubular substrate element.

[0118] The one or more protrusions may be non-integral with the hollow tubular substrate element. That is, the one or more protrusions may be physically separate from the hollow tubular substrate element. The one or more protrusions may be directly or indirectly adhered to the outer surface of the hollow tubular substrate element or otherwise attached.

[0119] The one or more protrusions may be integral with the outer wrapper. The one or more protrusions may be formed by a fold or folds within the outer wrapper. The one or more protrusions may be formed by crimping the outer wrapper.

[0120] One or more protrusions may be non-integral with the outer wrapper. For example, one or more protrusions may be attached directly or indirectly, adhesively or otherwise, to the inner surface of the outer wrapper.

[0121] One or more protrusions can be formed of a homogenized tobacco material. One or more protrusions may be formed of the same material as the hollow tubular substrate element. Advantageously, the aerosol may be generated from such protrusions and released into the empty space. This can further reduce the preheating time of the aerosol-generating article.

[0122] One or more protrusions may be formed of a material different from that of the hollow tubular substrate element.

[0123] One or more protrusions may extend along the entire length of the hollow tubular substrate element. Alternatively, one or more protrusions may not extend along the entire length of the hollow tubular substrate element. One or more protrusions may extend over a portion of the length of the hollow tubular substrate element.

[0124] One or more protrusions may be in the form of one or more disks. The disks may be inserted onto the hollow tubular substrate element. The disks may have an outer diameter substantially the same as the outer diameter of the aerosol-generating article. The disks may have an inner diameter substantially the same as the outer diameter of the hollow tubular substrate element. One or more disks may be arranged so as not to substantially impede or prevent the aerosol within the empty space from being drawn into the cavity in the longitudinal axis direction of the hollow tubular substrate element through the plurality of perforations of the hollow tubular substrate element.

[0125] One or more protrusions may be arranged such that the empty space is discontinuous. That is, the empty space may comprise a plurality of channels defined by one or more protrusions. The plurality of channels of the empty space may be arranged substantially in the longitudinal axis direction along the aerosol-generating substrate. For example, the empty space may comprise a plurality of longitudinal axis channels defined by two or more protrusions extending along the entire length of the hollow tubular substrate element.

[0126] When the aerosol generating substrate includes a plurality of protrusions, the plurality of protrusions may be spaced apart substantially evenly around the hollow tubular substrate element.

[0127] The empty space may be an annular empty space.

[0128] The empty space may have an annular cross-section.

[0129] The empty space may be annular along the entire length of the hollow tubular substrate element. That is, the empty space may have an annular cross-section along the entire length of the hollow tubular substrate element.

[0130] The aerosol generating substrate may be composed of an upstream element adjacent to the upstream end of the hollow tubular substrate element. By providing the upstream element, the hollow tubular substrate element can be more protected than a hollow tubular substrate element without an upstream element upstream of the hollow tubular substrate element. The upstream element may also help to define an empty space between the hollow tubular substrate element and the outer wrapper. The upstream element may be sized and positioned such that the empty space does not extend to the upstream end of the aerosol generating article or the aerosol generating substrate.

[0131] The upstream element may abut against the upstream end of the hollow tubular substrate element. The upstream element may be attached to the hollow tubular substrate element.

[0132] The upstream element may be located at the upstream end of the aerosol generating substrate. The upstream element may be located at the upstream end of the aerosol generating article.

[0133] The outer wrapper may surround at least a portion of the hollow tubular substrate element and the upstream element. The outer wrapper can surround the entire length of the upstream element.

[0134] The upstream element may be an upstream plug element. For example, the upstream element may be a plug of cellulose acetate tow.

[0135] Preferably, the outer diameter of the upstream element is substantially the same as the outer diameter of the aerosol generating substrate. Preferably, the outer diameter of the upstream element is substantially the same as the outer diameter of the aerosol generating article.

[0136] The outer diameter of the upstream element may be at least about 5 millimeters, or at least about 5.5 millimeters, or at least about 6 millimeters.

[0137] The outer diameter of the upstream element may be at most about 10 millimeters, or at most about 9 millimeters, or at most about 8 millimeters.

[0138] For example, the outer diameter of the upstream element may be from about 5 millimeters to about 10 millimeters, or from about 5.5 millimeters to about 9 millimeters, or from about 6 millimeters to about 8 millimeters.

[0139] The outer diameter of the upstream element may be larger than the outer diameter of at least a part of the hollow tubular substrate element. This may be such that an empty space is defined between the outer surface of the hollow tubular substrate element and an outer wrapper surrounding at least a part of the hollow tubular substrate element and the upstream element.

[0140] Preferably, the outer diameter of at least a part of the hollow tubular substrate element is at least about 0.1 millimeter smaller than the outer diameter of the upstream element, or at least about 0.2 millimeter smaller than the outer diameter of the upstream element.

[0141] Preferably, the outer diameter of at least a part of the hollow tubular substrate element is at most about 6 millimeters smaller than the outer diameter of the upstream element, at most about 4.5 millimeters smaller than the outer diameter of the upstream element, or at most 3 millimeters smaller than the outer diameter of the upstream element.

[0142] For example, the outer diameter of at least a part of the hollow tubular substrate element may be from about 0.1 millimeter to about 6 millimeters smaller than the outer diameter of the upstream element, or from about 0.2 millimeter to about 3 millimeters smaller than the outer diameter of the upstream element.

[0143] The outer diameter of at least a part of the hollow tubular base element may be about 0.2 millimeters smaller than the outer diameter of the upstream element.

[0144] The difference between the outer diameter of the hollow tubular base element and the outer diameter of the upstream element can define the size of the empty space. In particular, the difference between the outer diameter of the hollow tubular base element and the outer diameter of the upstream element may be equal to twice the separation across the empty space between the outer surface of the hollow tubular base element and the outer wrapper. Thus, the difference between the outer diameter of the hollow tubular base element and the outer diameter of the upstream element may be selected based on the desired size of the empty space.

[0145] The upstream element can have a length of at least about 2 millimeters, or at least about 3 millimeters, or at least about 5 millimeters.

[0146] The upstream element can have a length of at most about 15 millimeters, or at most about 12 millimeters, or at most about 10 millimeters.

[0147] For example, the upstream element can have a length between about 2 millimeters and about 15 millimeters, or between about 3 millimeters and about 12 millimeters, or between about 5 millimeters and about 10 millimeters.

[0148] The upstream element may have a length of about 5 millimeters.

[0149] The length of the upstream element may be selected based on the position of the external heating element within the corresponding aerosol generating device in order to align the hollow tubular element with the external heating element when the aerosol generating article is fully inserted into the aerosol generating device.

[0150] The aerosol generating substrate may include a downstream element adjacent to the downstream end of the hollow tubular base element. The downstream element may abut against the downstream end of the hollow tubular base element. The downstream element can be attached to the hollow tubular base element.

[0151] The downstream element may be provided at the downstream end of the aerosol generating substrate. The downstream element may be in contact with a section on the downstream side of the aerosol generating article.

[0152] The outer wrapper may surround at least a part of the hollow tubular substrate element and the downstream element. The outer wrapper can surround the entire length of the downstream element.

[0153] The characteristics of the upstream element discussed above may be equally applicable to the downstream element. For example, at least one of the shape, size, and material of the upstream element discussed above may be applied to the downstream element. The downstream element may be the same as the upstream element.

[0154] The downstream element may be a downstream plug element. For example, the downstream element may be a plug of cellulose acetate tow.

[0155] Preferably, the outer diameter of the downstream element is substantially the same as the outer diameter of the aerosol generating substrate. Preferably, the outer diameter of the downstream element is substantially the same as the outer diameter of the aerosol generating article. Preferably, the outer diameter of the downstream element is substantially the same as the outer diameter of the upstream element. More preferably, the outer diameter of the downstream element is substantially the same as the outer diameter of the upstream element and the outer diameter of the aerosol generating article. This can help ensure that the outer diameter of the aerosol generating article is substantially constant along the length of the aerosol generating article.

[0156] The outer diameter of the downstream element may be at least about 5 millimeters, or at least about 5.5 millimeters, or at least about 6 millimeters.

[0157] The outer diameter of the downstream element may be at most about 10 millimeters, or at most about 9 millimeters, or at most about 8 millimeters.

[0158] For example, the outer diameter of the downstream element may be from about 5 millimeters to about 10 millimeters, or from about 5.5 millimeters to about 9 millimeters, or from about 6 millimeters to about 8 millimeters.

[0159] The outer diameter of the downstream element may be larger than the outer diameter of at least a part of the hollow tubular base element. This may be such that an empty space is defined between the outer surface of the hollow tubular base element and an outer wrapper surrounding at least a part of the hollow tubular base element and the downstream element.

[0160] Preferably, the outer diameter of at least a part of the hollow tubular base element is at least about 0.1 millimeter smaller than the outer diameter of the downstream element, or at least about 0.2 millimeter smaller than the outer diameter of the downstream element.

[0161] Preferably, the outer diameter of at least a part of the hollow tubular base element is at most about 6 millimeters smaller than the outer diameter of the downstream element, at most about 4.5 millimeters smaller than the outer diameter of the downstream element, or at most 3 millimeters smaller than the outer diameter of the downstream element.

[0162] For example, the outer diameter of at least a part of the hollow tubular base element may be from about 0.1 millimeter to about 6 millimeters smaller than the outer diameter of the downstream element, or from about 0.2 millimeter to about 3 millimeters smaller than the outer diameter of the downstream element. The outer diameter of at least a part of the hollow tubular base element may be about 0.2 millimeter smaller than the outer diameter of the downstream element.

[0163] The difference between the outer diameter of the hollow tubular base element and the outer diameter of the downstream element may define the size of the empty space. In particular, the difference between the outer diameter of the hollow tubular base element and the outer diameter of the downstream element may be equal to twice the separation across the empty space between the outer surface of the hollow tubular base element and the outer wrapper. Thus, the difference between the outer diameter of the hollow tubular base element and the outer diameter of the downstream element may be selected based on the desired size of the empty space.

[0164] The downstream element can have a length of at least about 2 millimeters, or at least about 3 millimeters, or at least about 5 millimeters.

[0165] The downstream element can have a length of up to about 15 millimeters, or up to about 12 millimeters, or up to about 10 millimeters.

[0166] For example, the downstream element can have a length between about 2 millimeters and about 15 millimeters, or between about 3 millimeters and about 12 millimeters, or between about 5 millimeters and about 10 millimeters.

[0167] The downstream element can have a length of about 5 millimeters.

[0168] The central longitudinal axis of the hollow tubular substrate element is preferably aligned with the central longitudinal axes of other elements of the aerosol-generating article, such as other components of the aerosol-generating substrate and components of the downstream section. For example, the central longitudinal axis of the hollow tubular substrate element preferably aligns with the central longitudinal axes of both the upstream and downstream elements. The central longitudinal axis of the hollow tubular substrate element is preferably aligned with the central longitudinal axis of the aerosol-generating article.

[0169] When the hollow tubular substrate element is disposed in contact with both the upstream and downstream elements, the hollow tubular substrate element may be supported between the upstream and downstream elements. The outer wrapper may be tightly wound around one or both of the upstream element, the hollow tubular substrate element, and the downstream element to hold the upstream element, the hollow tubular substrate element, and the downstream element in place.

[0170] The outer wrapper may not be attached to the hollow tubular substrate element.

[0171] The outer wrapper may be attached to one or both of the upstream and downstream elements.

[0172] The upstream element, the hollow tubular substrate element, and the downstream element may be attached to each other. This can also help hold the upstream element, the hollow tubular substrate element, and the downstream element in place.

[0173] Within the empty space, the outer surface of the hollow tubular substrate element and the outer wrapper may be separated by at least about 0.05 millimeters in the radial direction, or at least about 0.1 millimeters in the radial direction.

[0174] Within the empty space, the outer surface of the hollow tubular substrate element and the outer wrapper may be spaced apart by up to about 3 millimeters in the radial direction, up to about 2.25 millimeters in the radial direction, or up to about 1.5 millimeters in the radial direction.

[0175] For example, within the empty space, the outer surface of the hollow tubular substrate element and the outer wrapper may be spaced apart by about 0.05 millimeters to about 3 millimeters in the radial direction, or about 0.1 millimeters to about 1.5 millimeters in the radial direction.

[0176] Within the empty space, the outer surface of the hollow tubular substrate element and the outer wrapper may be spaced apart by about 0.1 millimeters in the radial direction.

[0177] As described above, the outer wrapper may surround the hollow tubular substrate element and at least a portion of both the upstream element and the downstream element, and may define an empty space between the outer wrapper and the hollow tubular substrate element. In other words, the empty space may be defined by the outer surface of the hollow tubular substrate element, a portion of the outer wrapper surrounding the hollow tubular substrate element, the downstream end face of the upstream element, and the upstream end face of the downstream element. Thus, by providing both the upstream element and the downstream element, an effective method of creating an empty space can be provided without the need for additional elements.

[0178] Preferably, the outer wrapper has sufficient structural rigidity so that it can hold an empty space between the outer wrapper and the hollow tubular substrate element. For example, the outer wrapper may have sufficient structural rigidity so that the outer wrapper does not collapse with the hollow tubular substrate element during the handling or storage of the aerosol generating article. However, it may be desirable for the outer wrapper to have some flexibility so that when the consumer sucks air through the aerosol generating article, the outer wrapper can be drawn towards the outer surface of the hollow tubular substrate element. This can help to force the aerosol in the empty space into the longitudinal cavity. The basis weight of the outer wrapper may be selected so that the outer wrapper has a desired balance between structural rigidity and flexibility.

[0179] The outer wrapper can have a basis weight of at least about 15 grams per square meter, or at least about 20 grams per square meter, or at least about 25 grams per square meter.

[0180] The outer wrapper may have a basis weight of up to about 100 grams per square meter, or up to about 90 grams per square meter, or up to about 80 grams per square meter, or up to 50 grams per square meter.

[0181] In some embodiments, the outer wrapper is preferably stiff, for example, the outer wrapper can have a basis weight of at least about 80 gsm (grams per square meter), or at least about 100 gsm, or at least about 110 gsm.

[0182] The outer wrapper may comprise a plurality of perforations on the hollow tubular substrate element. This allows air to be drawn into the empty space, which can increase the level of turbulence in the empty space.

[0183] Any wrapper surrounding the hollow tubular substrate element may comprise a plurality of perforations that are substantially aligned with the plurality of perforations of the outer wrapper.

[0184] Preferably, the plurality of perforations of the outer wrapper are arranged in one or more circumferential rows. That is, the outer wrapper may comprise one or more circumferential rows of perforations.

[0185] The outer wrapper may include at least two rows of perforations at the periphery.

[0186] The outer wrapper may comprise up to five circumferential rows of perforations.

[0187] The circumferential rows of perforations may follow various patterns. For example, the circumferential rows of perforations may be arranged circularly or helically around the hollow tubular substrate element.

[0188] Preferably, each circumferential row of perforations includes 8 to 30 perforations.

[0189] The characteristics of the plurality of perforations of the above-mentioned hollow tubular substrate element may be equally applicable to the plurality of perforations of the outer wrapper. For example, the outer wrapper may have the same number of rows of perforations and the same number of perforations per row as the hollow tubular substrate element.

[0190] The plurality of perforations of the outer wrapper may comprise at least one perforation having a maximum dimension of at least 200 micrometers, or at least 300 micrometers, or at least about 400 micrometers, or at least about 500 micrometers.

[0191] When the perforations of the outer wrapper are substantially circular, the maximum dimension of the perforation is the diameter of the perforation. The plurality of perforations of the outer wrapper may include at least one perforation having a maximum dimension of up to about 1 millimeter, or up to about 900 micrometers, or up to about 800 micrometers, or up to about 700 micrometers.

[0192] Each of the plurality of perforations of the outer wrapper may have a maximum dimension of at least 200 micrometers, at least 300 micrometers, at least 400 micrometers, or at least 500 micrometers.

[0193] Each of the plurality of perforations in the outer wrapper may have a maximum dimension of about 1 millimeter, or about 900 micrometers, or about 800 micrometers, or about 700 micrometers.

[0194] The plurality of perforations in the outer wrapper may include at least one perforation having an opening area of at least about 0.01 square millimeter, or at least 0.03 square millimeter, or at least 0.05 square millimeter, or at least 0.07 square millimeter.

[0195] The plurality of perforations in the outer wrapper may include at least one perforation having an opening area of 1 square millimeter or less, or 0.8 square millimeter or less, or 0.5 square millimeter or less, or 0.3 square millimeter or less, or 0.1 square millimeter or less.

[0196] Each of the plurality of perforation lines in the outer wrapper may have an opening area of at least about 0.01 square millimeter, or at least about 0.03 square millimeter, or at least about 0.05 square millimeter, or at least about 0.07 square millimeter.

[0197] Each of the plurality of perforations in the outer wrapper may have an opening area of 1 square millimeter or less, or 0.8 square millimeter or less, or 0.5 square millimeter or less, or 0.3 square millimeter or less, or 0.1 square millimeter or less.

[0198] The plurality of perforation lines in the outer packaging material may have a total opening area of at least about 0.05 square millimeter, or at least about 0.2 square millimeter, or at least about 0.35 square millimeter, or at least about 0.5 square millimeter.

[0199] The plurality of perforations in the outer wrapper may have a total opening area of up to about 30 square millimeters, or up to about 25 square millimeters, or up to about 15 square millimeters, or up to about 10 square millimeters, or up to about 5 square millimeters.

[0200] The plurality of perforations in the outer wrapper may be over an empty space.

[0201] The plurality of perforations in the outer wrapper is preferably over the plurality of perforations of the hollow tubular substrate element. That is, the plurality of perforations in the outer wrapper is preferably substantially aligned with the plurality of perforations of the hollow tubular substrate element. This may be such that the aerosol generating article has a desired RTD. This may also simplify the manufacture of the aerosol generating article since the plurality of perforations in the outer wrapper and the plurality of perforations of the hollow tubular substrate element can be formed simultaneously after surrounding the hollow tubular substrate element with the outer wrapper.

[0202] The plurality of perforations may be formed using any suitable well-known method, such as online during the manufacture of the aerosol generating article.

[0203] The outer wrapper is preferably non-porous so that the airflow into the aerosol generating article can be controlled. For example, the non-porous outer wrapper can prevent air from entering the upstream and downstream elements through the outer wrapper.

[0204] The rod of the aerosol generating substrate may include one or more susceptor elements disposed in contact with the hollow tubular substrate element to inductively heat the homogenized tobacco material during use.

[0205] As used herein, the term "susceptor element" refers to an element that includes a material having the ability to convert electromagnetic energy into heat. When the susceptor element is located within an alternating electromagnetic field, the susceptor is heated. The heating of the susceptor element can be the result of at least one of the hysteresis losses and eddy currents induced within the susceptor, depending on the electrical and magnetic properties of the susceptor material.

[0206] Preferably, the rod of the aerosol generating substrate comprises one or more susceptor elements on the surface of a hollow tubular substrate element. The hollow tubular substrate element may comprise one or more susceptor elements on the inner surface of the hollow tubular substrate element. Alternatively or additionally, the rod of the aerosol generating substrate may comprise one or more susceptor elements on the outer surface of the hollow tubular substrate element.

[0207] The one or more susceptor elements may be positioned away from the plurality of perforations of the hollow tubular substrate element such that air and aerosol can flow from the empty space through the plurality of perforations of the hollow tubular substrate element into the hollow cavity.

[0208] The one or more susceptor elements may comprise a plurality of perforations. The plurality of perforations of the one or more susceptor elements are preferably arranged to substantially coincide with the plurality of perforations of the hollow tubular substrate element. That is, the plurality of perforations of the one or more susceptor elements are preferably substantially aligned with the plurality of perforations of the hollow tubular substrate element. This can be such that air and aerosol can flow from the empty space through the plurality of perforations of the hollow tubular substrate element and through the plurality of perforations of the one or more susceptor elements into the hollow cavity. For example, the one or more susceptor elements may be in the form of one or more perforated sheets.

[0209] The one or more susceptor elements may be embedded within the wall of the hollow tubular substrate element.

[0210] The susceptor element can comprise any suitable material. The susceptor element can be formed from any material that can be inductively heated to a temperature sufficient to release volatile compounds from the aerosol-generating substrate. Suitable materials for an elongate susceptor element include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Some susceptor elements include metal or carbon. Advantageously, the susceptor element can comprise or consist of a ferromagnetic material such as, for example, ferromagnetic iron, ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrite. A suitable susceptor element is aluminum or can include aluminum. The susceptor element preferably includes a ferromagnetic material or a paramagnetic material in an amount greater than about 5 percent, preferably greater than about 20 percent, more preferably greater than about 50 percent or greater than about 90 percent. Some elongate susceptor elements can be heated to a temperature in excess of about 250 degrees Celsius.

[0211] The aerosol-generating substrate can have a length of at least about 10 millimeters, at least about 12 millimeters, or at least about 15 millimeters.

[0212] The aerosol-generating substrate can have a length of up to about 40 millimeters, up to about 37 millimeters, or up to about 35 millimeters.

[0213] For example, the aerosol-generating substrate can have a length of from about 10 millimeters to about 40 millimeters, or from about 12 millimeters to about 37 millimeters, or from about 15 millimeters to about 35 millimeters.

[0214] The aerosol-generating substrate can have a length greater than the length of the hollow tubular substrate element.

[0215] As defined above, in the aerosol generating article of the present invention, the aerosol generating substrate including the hollow tubular substrate element is combined with a downstream section located downstream of the aerosol generating substrate. The downstream section is preferably located immediately downstream of the aerosol generating substrate. The downstream section of the aerosol generating article preferably extends between 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 the present disclosure.

[0216] The downstream section preferably comprises at least one hollow tubular element. The hollow tubular element may be adjacent to the downstream end of the rod of the aerosol generating substrate. The hollow tubular element may be installed immediately downstream of the aerosol generating substrate. In other words, the hollow tubular element may abut against the downstream end of the aerosol generating substrate. By this arrangement, the flow of aerosol from the longitudinal airflow channel of the hollow tubular substrate element into the downstream section and through the aerosol generating article can be optimized.

[0217] The downstream section of the aerosol generating article preferably comprises a single hollow tubular element. In other words, the downstream section of the aerosol generating article may comprise only one hollow tubular element.

[0218] The hollow tubular element of the downstream section may also be referred to as the hollow tubular downstream element.

[0219] In the context of the present invention, the hollow tubular element of the downstream section provides an unrestricted flow channel through the airflow path. This means that the hollow tubular element provides a negligible level of draw resistance (RTD) as defined above. Thus, the airflow path should not include any components that would impede the longitudinal airflow. Preferably, the airflow path is substantially empty.

[0220] The hollow tubular element of the downstream section provides an empty cavity downstream of the aerosol generation substrate, whereby the cooling and nucleation of the aerosol particles generated by the aerosol generation substrate can be improved. Thus, the hollow tubular element of the downstream section can function as an aerosol cooling element.

[0221] The length of the hollow tubular element can be at least about 12 mm. The length of the hollow tubular element can be at least about 15 mm. The length of the hollow tubular element can be at least about 20 mm.

[0222] The length of the hollow tubular element of the downstream section can be about 50 mm or less. The length of the hollow tubular element can be about 45 mm or less. The length of the hollow tubular element can be about 40 mm or less.

[0223] For example, the length of the hollow tubular element of the downstream section can be about 12 mm to 50 mm. The length of the hollow tubular element can be about 15 mm to 45 mm. The length of the hollow tubular element can be about 20 mm to about 40 mm. The length of the hollow tubular element can be about 30 mm.

[0224] A relatively long hollow tubular element provides and defines a relatively long internal cavity within the downstream section of the aerosol generating article. By providing a relatively long cavity, the above-mentioned advantages of nucleation can be maximized, thereby improving aerosol formation and cooling.

[0225] The ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element of the downstream section can be about 1.25 or less. Preferably, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element of the downstream section can be about 1 or less. More preferably, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element of the downstream section can be about 0.75 or less.

[0226] The ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element of the downstream section may be at least about 0.2. Preferably, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element of the downstream section may be at least about 0.25. More preferably, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element of the downstream section may be at least about 0.3.

[0227] For example, the ratio of the length of the hollow tubular substrate element to the length of the hollow tubular element of the downstream section may be from about 0.2 to about 1.25, or from about 0.25 to about 1, or from about 0.3 to about 0.75.

[0228] The ratio of the length of the hollow tubular element of the downstream section to the total length of the downstream section may be about 1 or less. Preferably, the ratio of the length of the hollow tubular element of the downstream section to the total length of the downstream section may be about 0.90 or less. More preferably, the ratio of the length of the hollow tubular element of the downstream section to the total length of the downstream section may be about 0.85 or less.

[0229] The ratio of the length of the hollow tubular element of the downstream section to the total length of the downstream section may be at least about 0.35. Preferably, the ratio of the length of the hollow tubular element of the downstream section to the total length of the downstream section may be at least about 0.45. More preferably, the ratio of the length of the hollow tubular element of the downstream section to the total length of the downstream section may be at least about 0.50.

[0230] For example, the ratio of the length of the hollow tubular element of the downstream section to the total length of the downstream section may be from about 0.35 to about 1, or from about 0.45 to about 0.9, or from about 0.5 to about 0.85.

[0231] The ratio of the length of the hollow tubular element in the downstream section to the total length of the aerosol generating article may be about 0.80 or less. Preferably, the ratio of the length of the hollow tubular element in the downstream section to the total length of the aerosol generating article may be about 0.70 or less. More preferably, the ratio of the length of the hollow tubular element in the downstream section to the total length of the aerosol generating article may be about 0.60 or less.

[0232] The ratio of the length of the hollow tubular element in the downstream section to the total length of the aerosol generating article may be at least about 0.25. Preferably, the ratio of the length of the hollow tubular element in the downstream section to the total length of the aerosol generating article may be at least about 0.30. More preferably, the ratio of the length of the hollow tubular element in the downstream section to the total length of the aerosol generating article may be at least about 0.40.

[0233] For example, the ratio of the length of the hollow tubular element in the downstream section to the total length of the aerosol generating article may be from about 0.25 to about 0.8, or from about 0.3 to about 0.7, or from about 0.4 to about 0.6.

[0234] The wall thickness of the hollow tubular element in the downstream section may be at least about 100 micrometers. The wall thickness of the hollow tubular element in the downstream section may be at least about 150 micrometers. The wall thickness of the hollow tubular element in the downstream section may be at least about 200 micrometers, preferably at least about 250 micrometers, and even more preferably at least about 500 micrometers (or 0.5 mm).

[0235] The wall thickness of the hollow tubular element in the downstream section may be about 2 millimeters or less, preferably about 1.5 millimeters or less, and even more preferably about 1.25 mm or less. The wall thickness of the hollow tubular element in the downstream section may be about 1 millimeter or less. The wall thickness of the hollow tubular element in the downstream section may be about 500 micrometers or less.

[0236] The wall thickness of the hollow tubular element of the downstream section can be from about 100 micrometers to about 2 millimeters, preferably from about 150 micrometers to about 1.5 millimeters, and even more preferably from about 200 micrometers to about 1.25 millimeters.

[0237] By keeping the wall thickness of the hollow tubular segment of the downstream section relatively small, the overall internal volume of the hollow tubular element (which is made available for the aerosol to initiate the nucleation process as soon as the aerosol component leaves the aerosol generating substrate) and the cross-sectional surface area of the hollow tubular element are effectively maximized, while at the same time ensuring that the hollow tubular element has the structural strength necessary not only to prevent the disintegration of the aerosol generating article but also to provide some support to the rod of the aerosol generating substrate, and that the RTD of the hollow tubular element is minimized. A larger value of the cross-sectional surface area of the cavity of the hollow tubular element is understood to be associated with a reduced speed of the aerosol flow along the aerosol generating article, which is also expected to be advantageous for aerosol nucleation. Furthermore, by utilizing a hollow tubular element with a relatively small thickness, it may be possible to substantially prevent the diffusion of the ventilation air before it comes into contact with and mixes with the aerosol flow, which is also understood to be more advantageous for the nucleation phenomenon. In fact, by providing a more controllably localized cooling of the flow of the volatile species, it may be possible to enhance the cooling effect on the formation of new aerosol particles.

[0238] The hollow tubular element of the downstream section preferably has an outer diameter substantially equal to the outer diameter of the aerosol generating substrate and the outer diameter of the aerosol generating article. The hollow tubular element of the downstream section preferably has an outer diameter larger than the outer diameter of the hollow tubular substrate element of the aerosol generating substrate.

[0239] The hollow tubular element may have an outer diameter of 5 millimeters to 10 millimeters, for example, 5.5 millimeters to 9 millimeters, or 6 millimeters to 8 millimeters.

[0240] The hollow tubular element of the downstream section may have a constant inner diameter along the length of the hollow tubular element. However, the inner diameter of the hollow tubular element may vary along the length of the hollow tubular element.

[0241] The hollow tubular element of the downstream section may have an inner diameter of at least about 2 millimeters. For example, the hollow tubular element may have an inner diameter of at least about 2.5 millimeters, at least about 3 millimeters, or at least about 3.5 millimeters. By installing a hollow tubular element having an inner diameter as presented above, advantageously, sufficient rigidity and strength can be provided to the hollow tubular element.

[0242] The hollow tubular element of the downstream section may have an inner diameter of about 10 millimeters or less. For example, the hollow tubular element may have an inner diameter of about 9 millimeters or less, about 8 millimeters or less, or about 7.5 millimeters or less. By providing a hollow tubular element having an inner diameter as described above, the pulling resistance of the hollow tubular segment can be advantageously reduced.

[0243] For example, the hollow tubular element of the downstream section may have an inner diameter of about 2 millimeters to about 10 millimeters, about 2.5 millimeters to about 9 millimeters, about 3 millimeters to about 8 millimeters, or 3.5 millimeters to about 7.5 millimeters.

[0244] The ratio of the inner diameter of the hollow tubular base element to the inner diameter of the hollow tubular element of the downstream section is preferably about 0.8 to about 1.2, more preferably about 0.9 to about 1.1, and most preferably about 1.

[0245] Particularly preferably, the inner diameter of the hollow tubular base element is substantially equal to the inner diameter of the hollow tubular element of the downstream section.

[0246] The central longitudinal axis of the hollow tubular substrate element of the aerosol generating substrate may preferably be aligned with the central longitudinal axis of the hollow tubular element of the downstream section. For example, the inner diameter of the hollow tubular substrate element is substantially equal to the inner diameter of the hollow tubular element of the downstream section, and the central longitudinal axis of the hollow tubular substrate element may be aligned with the central longitudinal axis of the hollow tubular element of the downstream section such that the cavity of the hollow tubular substrate element and the cavity of the hollow tubular element of the downstream section can be substantially aligned.

[0247] The hollow tubular element of the downstream section may comprise a paper-based material. The hollow tubular element may comprise at least one layer of paper. The paper can be very stiff paper. The paper can be curled paper such as heat-resistant curled paper or curled sulfuric acid paper.

[0248] Preferably, the hollow tubular element may comprise cardboard. The hollow tubular element can be a cardboard tube. The hollow tubular element can be formed from cardboard. Advantageously, cardboard provides a balance between being deformable to facilitate the insertion of articles into the aerosol generating device and being sufficiently rigid to provide proper engagement of the aerosol generating article with the interior of the device, and is a cost-effective material. Thus, the cardboard tube may provide appropriate resistance to deformation or compression during use.

[0249] The hollow tubular element of the downstream section may be a paper tube. The hollow tubular element may be a tube formed from spirally wound paper. The hollow tubular element may be formed from a plurality of layers of paper. The paper may have a basis weight of about 50 grams per square meter, at least about 60 grams per square meter, at least about 70 grams per square meter, or at least about 90 grams per square meter.

[0250] The hollow tubular element of the downstream section may comprise a polymeric material. For example, the hollow tubular element may comprise a polymeric film. The polymeric film may comprise a cellulose film. The hollow tubular segment may comprise low density polyethylene (LDPE) or polyhydroxyalkanoate (PHA) fibers. The hollow tube may comprise cellulose acetate tow.

[0251] When the hollow tubular element comprises cellulose acetate tow, the cellulose acetate tow may have from about 2 to about 4 denier per filament and from about 25 to about 40 total denier per filament.

[0252] The hollow tubular element may be at the upstream end of the downstream section. The hollow tubular element may abut the downstream end of the aerosol generating substrate. The hollow tubular element may be in contact with the downstream end of a hollow tubular substrate element.

[0253] The outer wrapper of the aerosol generating substrate may also surround at least a portion of the downstream section of the aerosol generating article. For example, the outer wrapper of the aerosol generating substrate may also surround at least a portion of the hollow tubular element of the downstream section.

[0254] The aerosol generating article according to the present invention may include a ventilation zone at a location along the downstream section. More particularly, when the downstream section comprises a hollow tubular element, the ventilation zone may be provided at a position along the hollow tubular element.

[0255] Thus, a vented cavity is provided downstream of the rod of the aerosol generating substrate. Thereby, particularly efficient cooling of the aerosol is provided and improvement of nucleation of aerosol particles can be promoted.

[0256] The ventilation zone may typically include a plurality of perforations through the peripheral wall of the hollow tubular element. The plurality of perforations of the ventilation zone can also penetrate any wrapper surrounding the hollow tubular element. The ventilation zone preferably comprises at least one circumferential row of perforations. The ventilation zone may include 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 includes from 8 to 30 perforations.

[0257] The downstream section may further comprise a mouthpiece element. The mouthpiece element may be located at the downstream end of the aerosol generating article. The mouthpiece element is preferably located downstream of the hollow tubular element of the downstream section as described above. The mouthpiece element may extend between the hollow tubular element of the downstream section and the downstream end of the aerosol generating article.

[0258] Providing a mouthpiece element at the downstream end of the aerosol generating article according to the present invention can provide an attractive appearance and feel for the consumer.

[0259] The mouthpiece element may be a mouthpiece filter element. The mouthpiece element may comprise at least one mouthpiece filter segment formed of a fibrous filter material. Parameters or characteristics described with respect to the entire mouthpiece element may equally apply to the mouthpiece filter segments of the mouthpiece element.

[0260] 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 mouthpiece filter segment includes a cellulose acetate filter segment formed from cellulose acetate tow.

[0261] The mouthpiece element may be composed of a single mouthpiece filter segment. The mouthpiece element may include two or more mouthpiece filter segments that are in contact with each other end-to-end and axially aligned.

[0262] The downstream section may have a mouth-side end cavity at the downstream end of the downstream of the mouthpiece element as described above. The mouth-side end cavity may be defined by a further hollow tubular element provided at the downstream end of the mouthpiece element. The mouth-side end cavity may be defined by an outer wrapper of the aerosol generating article, and the outer wrapper extends in the downstream direction from (or past) the mouthpiece element. For example, the mouth-side indentation may be defined by a tipping wrapper that extends downstream beyond the mouthpiece element.

[0263] The mouthpiece element may optionally contain a flavorant provided in any suitable form. For example, the mouthpiece element may comprise one or more capsules, beads, or granules of flavorant, or one or more threads or filaments loaded with flavor.

[0264] Preferably, the mouthpiece element, or its mouthpiece filter segment, has a low particle filtration efficiency.

[0265] Preferably, the mouthpiece element is surrounded by a plug wrap. Preferably, the mouthpiece element is not ventilated so that air does not enter the aerosol generating article along the mouthpiece element.

[0266] The mouthpiece element preferably has an outer diameter that is approximately equal to the outer diameter of the aerosol generating article. The diameter of the mouthpiece element (or mouthpiece filter segment) may be substantially the same as the outer diameter of the hollow tubular element. As described in the present disclosure, the outer diameter of the hollow tubular element may be about 7.2 mm plus or minus 10 percent.

[0267] The diameter of the mouthpiece element can be from about 5 mm to about 10 mm. The diameter of the mouthpiece element can be from about 5.5 mm to about 9 mm. The diameter of the mouthpiece element can be from about 6 mm to about 8 mm. The diameter of the mouthpiece element can be about 7.2 mm ± 10 percent. The diameter of the mouthpiece element can be about 7.25 mm ± 10 percent.

[0268] Unless otherwise specified, the draw resistance (RTD) of a component or aerosol-generating article is measured in accordance with ISO 6565-2015. RTD refers to the pressure required to pass 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".

[0269] The draw resistance (RTD) of the downstream section can be at least about 0 mmH2O. The RTD of the downstream section can be at least about 3 mmH2O. The RTD of the downstream section can be at least about 6 mmH2O.

[0270] The RTD of the downstream section can be about 12 mmH2O or less. The RTD of the downstream section can be about 11 mmH2O or less. The RTD of the downstream section can be about 10 mmH2O or less.

[0271] The draw resistance of the downstream section can be from about 0 mmH2O or more and less than about 12 mmH2O. Preferably, the draw resistance of the downstream section can be from about 3 mmH2O or more and less than about 12 mmH2O. The draw resistance of the downstream section can be from about 0 mmH2O or more and less than about 11 mmH2O. Even more preferably, the draw resistance of the downstream section can be from about 3 mmH2O or more and less than about 11 mmH2O. Even more preferably, the draw resistance of the downstream section can be from about 6 mmH2O or more and less than about 10 mmH2O. Preferably, the draw resistance of the downstream section can be about 8 mmH2O.

[0272] The pull - out resistance (RTD) characteristics of the downstream section may be entirely or mostly due to the RTD characteristics of the mouthpiece element of the downstream section. In other words, the RTD of the mouthpiece element of the downstream section may fully define the RTD of the downstream section.

[0273] The pull - out resistance (RTD) of the mouthpiece element can be at least about 0 mmH2O. The RTD of the mouthpiece element can be at least about 3 mmH2O. The RTD of the mouthpiece element can be at least about 6 mmH2O.

[0274] The RTD of the mouthpiece element can be about 12 mmH2O or less. The RTD of the mouthpiece element can be about 11 mmH2O or less. The RTD of the mouthpiece element can be about 10 mmH2O or less.

[0275] The pull - out resistance of the mouthpiece element can be more than about 0 mmH2O and less than about 12 mmH2O. Preferably, the pull - out resistance of the mouthpiece element can be more than about 3 mmH2O and less than about 12 mmH2O. The pull - out resistance of the mouthpiece element can be more than about 0 mmH2O and less than about 11 mmH2O. Even more preferably, the pull - out resistance of the mouthpiece element can be more than about 3 mmH2O and less than about 11 mmH2O. Even more preferably, the pull - out resistance of the mouthpiece element can be more than about 6 mmH2O and less than about 10 mmH2O. Preferably, the pull - out resistance of the mouthpiece element can be about 8 mmH2O.

[0276] As described above, the mouthpiece element or mouthpiece filter segment can be formed of a fibrous material. The mouthpiece element can be formed of a porous material. The mouthpiece element can be formed of a biodegradable material. The mouthpiece element can be formed of a cellulose material such as cellulose acetate. For example, the mouthpiece element can be formed from a bundle of cellulose acetate fibers having about 10 to about 15 denier / filament. For example, the mouthpiece element is formed from a relatively low density cellulose acetate tow, such as a cellulose acetate tow containing fibers of about 12 denier per filament.

[0277] The mouthpiece element can be formed of a polylactic acid-based material. The mouthpiece element can be formed of a bioplastic material, preferably a starch-based bioplastic material. The mouthpiece element can be produced by injection molding or extrusion molding. The bioplastic-based material is advantageous because it can provide a simple and inexpensive structure for the mouthpiece element to have a specific and complex cross-sectional profile with a plurality of relatively large air flow channels extending through the material of the mouthpiece element that provide suitable RTD characteristics.

[0278] The mouthpiece element can be formed from a suitable material sheet that is curled, pleated, assembled, woven, or folded into an element that defines a plurality of channels extending in the longitudinal direction. Such sheets of suitable materials can be formed of paper, cardboard, polymers such as polylactic acid, or any other cellulose-based, paper-based material or bioplastic-based material. The cross-sectional profile of such a mouthpiece element may exhibit randomly oriented channels.

[0279] The mouthpiece element can be formed in any other suitable manner. For example, the mouthpiece element can be formed from a bundle of tubes extending in the major axis direction. The tubes extending in the major axis direction can be formed from polylactic acid. The mouthpiece element can be formed by extrusion molding, molding, lamination, injection molding, or shredding of a suitable material. Therefore, it is preferable that the pressure drop (or RTD) is low from the upstream end to the downstream end of the mouthpiece element.

[0280] The length of the mouthpiece element can be at least about 1.5 mm. The length of the mouthpiece element can be at least about 2 mm. The length of the mouthpiece element can be about 7 mm or less. The length of the mouthpiece element can be about 4 mm or less. For example, the length of the mouthpiece element can be about 1.5 mm to about 7 mm. The length of the mouthpiece element can be about 2 mm to about 4 mm.

[0281] The ratio of the length of the mouthpiece element to the length of the downstream section can be about 0.35 or less. Preferably, the ratio of the length of the mouthpiece element to the length of the downstream section can be about 0.30 or less. More preferably, the ratio of the length of the mouthpiece element to the length of the downstream section can be about 0.25 or less.

[0282] The ratio of the length of the mouthpiece element to the length of the downstream section can be at least about 0.03. Preferably, the ratio of the length of the mouthpiece element to the length of the downstream section can be at least about 0.05. More preferably, the ratio of the length of the mouthpiece element to the length of the downstream section can be at least about 0.1.

[0283] For example, the ratio of the length of the mouthpiece element to the length of the downstream section is about 0.03 to about 0.35, preferably about 0.05 to about 0.30, more preferably about 0.1 to about 0.25.

[0284] The ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article can be about 0.20 or less. Preferably, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article can be about 0.15 or less. More preferably, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article can be about 0.1 or less.

[0285] The ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article can be at least about 0.01. Preferably, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article can be at least about 0.02. More preferably, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article can be at least about 0.05.

[0286] For example, the ratio of the length of the mouthpiece element to the overall length of the aerosol-generating article is from about 0.01 to about 0.2, preferably from about 0.02 to about 0.15, more preferably from about 0.05 to about 0.1.

[0287] When the downstream section comprises a hollow tubular element and a mouthpiece element, the ratio of the length of the hollow tubular element to the length of the mouthpiece element can be at least about 1.5. In other words, the length of the hollow tubular element can be at least about 150% of the length of the mouthpiece. The ratio of the length of the hollow tubular element to the length of the mouthpiece element can be at least about 5. The ratio of the length of the hollow tubular element to the length of the mouthpiece element can be at least about 7.5.

[0288] The ratio of the length of the hollow tubular element to the length of the mouthpiece element can be about 20 or less. The ratio of the length of the hollow tubular element to the length of the mouthpiece element can be about 15 or less. The ratio of the length of the hollow tubular element to the length of the mouthpiece element can be about 12.5 or less.

[0289] For example, the ratio of the length of the hollow tubular element to the length of the mouthpiece element can be from about 1.5 to about 20, or from about 5 to about 15, or from about 7.5 to about 10.

[0290] The total length of the downstream section is preferably at least about 15 millimeters, more preferably at least about 20 millimeters, and even more preferably at least about 25 millimeters.

[0291] The total length of the downstream section is preferably less than about 50 millimeters, more preferably less than about 45 millimeters, and even more preferably less than about 40 millimeters.

[0292] For example, the downstream section can have a total length of from about 20 millimeters to about 50 millimeters, more preferably from about 25 millimeters to about 45 millimeters, and even more preferably from about 30 millimeters to about 40 millimeters.

[0293] The ratio of the length of the downstream section to the total length of the aerosol-generating article can be about 0.80 or less. Preferably, the ratio of the length of the downstream section to the total length of the aerosol-generating article can be about 0.75 or less. More preferably, the ratio of the length of the downstream section to the total length of the aerosol-generating article can be about 0.70 or less. Even more preferably, the ratio of the length of the downstream section to the total length of the aerosol-generating article can be about 0.65 or less.

[0294] The ratio of the length of the downstream section to the total length of the aerosol-generating article can be at least about 0.30. Preferably, the ratio of the length of the downstream section to the total length of the aerosol-generating article can be at least about 0.40. More preferably, the ratio of the length of the downstream section to the total length of the aerosol-generating article can be at least about 0.50. Even more preferably, the ratio of the length of the downstream section to the total length of the aerosol-generating article can be at least about 0.60.

[0295] Preferably, the overall length of the aerosol generating article according to the present invention is at least about 35 millimeters. More preferably, the overall length of the aerosol generating article according to the present invention is at least about 40 millimeters. Even more preferably, the overall length of the aerosol generating article according to the present invention is at least about 45 millimeters. Even more preferably, the overall length of the aerosol generating article according to the present invention is at least about 50 millimeters.

[0296] Preferably, the overall length of the aerosol generating article according to the present invention is 110 millimeters or less. More preferably, the overall length of the aerosol generating article according to the present invention is 100 millimeters or less. Even more preferably, the overall length of the aerosol generating article according to the present invention is preferably 75 millimeters or less. Even more preferably, the overall length of the aerosol generating article according to the present invention is 70 millimeters or less.

[0297] For example, the overall length of the aerosol generating article may be from about 35 millimeters to about 110 millimeters, or from about 40 millimeters to about 100 millimeters, or from about 45 millimeters to about 75 millimeters, or from about 50 millimeters to about 70 millimeters.

[0298] Preferably, the aerosol generating article has an outer diameter of at least about 5 millimeters. Preferably, the aerosol generating article has an outer diameter of at least 5.5 millimeters. More preferably, the aerosol generating article has an outer diameter of at least 6 millimeters.

[0299] Preferably, the aerosol generating article has an outer diameter of about 10 millimeters or less. More preferably, the aerosol generating article has an outer diameter of about 9 millimeters or less. Even more preferably, the aerosol generating article has an outer diameter of about 8 millimeters or less.

[0300] For example, the aerosol generating article may have an outer diameter from about 5 millimeters to about 10 millimeters, or from about 5.5 millimeters to about 9 millimeters, or from about 6 millimeters to about 8 millimeters.

[0301] The outer diameter of the aerosol-generating article can be substantially constant over the entire length of the article. Alternatively, different portions of the aerosol-generating article can have different outer diameters.

[0302] One or more of the components of the aerosol-generating article may be individually surrounded by their wrappers.

[0303] The aerosol-generating substrate and the downstream section are preferably combined together with a wrapper such as a tipping wrapper.

[0304] The components of the aerosol-generating article according to the present invention are preferably made from biodegradable materials.

[0305] Preferably, the aerosol-generating article according to the present invention described herein is adapted for use in an electrically operated aerosol-generating system in which the aerosol-generating substrate of the heated aerosol-generating article is heated by an electrical heat source.

[0306] The heating element of such an aerosol-generating device can be in any suitable form for conducting heat. Heating of the aerosol-generating substrate may be achieved from the inside, from the outside, or from both. The heating element may be a heater blade or pin inserted into the aerosol-generating substrate and adapted to heat the substrate from the inside. The heating element preferably surrounds the substrate partially or completely and heats the substrate circumferentially from the outside.

[0307] The aerosol generating system may be an electrically operated aerosol generating system comprising an induction heating device. The induction heating device typically includes an induction source configured to be coupled to a susceptor, which may be provided external to the aerosol generating substrate or, as described above, internal to the aerosol generating substrate. The induction source generates an alternating electromagnetic field that induces magnetization or eddy currents within the susceptor. The susceptor may be heated as a result of hysteresis losses or induced eddy currents, which heat the susceptor through ohmic or resistive heating.

[0308] The electrically operated aerosol generating system comprising an induction heating device also comprises an aerosol generating article having an aerosol generating substrate and a susceptor in thermal proximity to the aerosol generating substrate. Typically, the susceptor is in direct contact with the aerosol generating substrate and heat is transferred from the susceptor to the aerosol generating substrate mainly by conduction. Examples of electrically operated aerosol generating systems having an aerosol generating article with an induction heating device and a susceptor are described in International Application No. WO-A1-95 / 27411 and International Application No. WO-A1-2015 / 177255.

[0309] An electrically operated aerosol generating system may, in some cases, comprise an aerosol generating article as defined above, a source of aerosol former, means for vaporizing the aerosol former, and preferably a heating element. The source of aerosol former can be a reservoir, which can be refillable or replaceable, and which is present on the aerosol generating device. While the reservoir is physically separated from the aerosol generating article, the vapor generated is directed through the aerosol generating article. The vapor contacts the aerosol generating substrate and releases volatile compounds such as nicotine and flavorants in the particulate plant material to form an aerosol. Optionally, to assist the volatilization of the compounds within the aerosol generating substrate, the aerosol generating system may further comprise a heating element for heating the aerosol generating substrate, preferably in a manner coordinated with the aerosol former. However, the heating element used to heat the aerosol generating article can be separated from the heater that heats the aerosol former.

[0310] As described above, the hollow tubular substrate element of the aerosol generating article according to the present invention can advantageously be adapted such that its length substantially matches the longitudinal dimension of the heating element of the aerosol generating system intended to be used to heat the aerosol generating article. Thereby, the hollow tubular substrate element is reliably heated substantially along its entire length, and as a result, the generation of aerosol from the aerosol generating substrate can be maximized.

[0311] The following provides a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more of the features of another example, or embodiment, or aspect described herein.

[0312] Example 1: An aerosol generating article comprising a rod of an aerosol generating substrate and a downstream section provided downstream of the rod of the aerosol generating substrate, wherein the rod of the aerosol generating substrate comprises a hollow tubular substrate element formed of a homogenized tobacco material and an outer wrapper surrounding the hollow tubular substrate element.

[0313] Example 2: The aerosol generating article according to Example 1, wherein the outer wrapper is arranged such that an empty space is defined between at least a part of the outer surface of the hollow tubular substrate element and the outer wrapper.

[0314] Example 3: The aerosol generating article according to Example 2, wherein the hollow tubular substrate element includes a plurality of perforations that provide fluid communication between the longitudinal axis cavity of the hollow tubular substrate element and the outer wrapper.

[0315] Example 4: The aerosol generating article according to any one of Examples 1 to 3, wherein the hollow tubular substrate element is formed from two or more overlapping layers of homogenized tobacco material.

[0316] Example 5: The aerosol generating article according to any one of Examples 1 to 4, wherein the hollow tubular substrate element is formed from a maximum of 10 overlapping layers of homogenized tobacco material.

[0317] Example 6: The aerosol generating article according to any one of Examples 1 to 5, wherein the hollow tubular substrate element has a length of at least 5 millimeters.

[0318] Example 7: The aerosol generating article according to any one of Examples 1 to 6, wherein the hollow tubular substrate element has a length of a maximum of about 30 millimeters.

[0319] Example 8: The aerosol generating article according to any one of Examples 1 to 7, wherein the ratio of the length of the hollow tubular substrate element to the total length of the aerosol generating article is at least about 0.1.

[0320] Example 9: The aerosol generating article according to any one of Examples 1 to 8, wherein the ratio of the length of the hollow tubular substrate element to the total length of the aerosol generating article is about 0.6 or less.

[0321] Example 10: The aerosol generating article according to any one of Examples 1 to 9, wherein the hollow tubular substrate element has an outer diameter that is smaller than the outer diameter of the aerosol generating article.

[0322] Example 11: An aerosol generating article according to any one of Examples 1 to 10, wherein the hollow tubular substrate element has an outer diameter of at least about 5 millimeters.

[0323] Example 12: An aerosol generating article according to any one of Examples 1 to 11, wherein the hollow tubular substrate element has an outer diameter of at most about 9 millimeters.

[0324] Example 13: An aerosol generating article according to any one of Examples 1 to 12, wherein the hollow tubular substrate element has a wall thickness that is at least about 4 percent of the outer diameter of the hollow tubular substrate element.

[0325] Example 14: An aerosol generating article according to any one of Examples 1 to 13, wherein the hollow tubular substrate element has a wall thickness that is at most about 40 percent of the outer diameter of the hollow tubular substrate element.

[0326] Example 15: An aerosol generating article according to any one of Examples 1 to 14, wherein the hollow tubular substrate element has a wall thickness of at least about 0.3 millimeters.

[0327] Example 16: An aerosol generating article according to any one of Examples 1 to 15, wherein the hollow tubular substrate element has a wall thickness of at most 3 millimeters.

[0328] Example 17: An aerosol generating article according to any one of Examples 1 to 16, wherein the cavity in the longitudinal direction has a diameter of at least 1 millimeter.

[0329] Example 18: An aerosol generating article according to any one of Examples 1 to 17, wherein the cavity in the longitudinal direction has a diameter of at most about 8 millimeters.

[0330] Example 19: An aerosol generating article according to any one of Examples 3 to 18, wherein the hollow tubular substrate element includes one or more rows of perforations extending circumferentially around the hollow tubular substrate element.

[0331] Example 20: An aerosol generating article according to any one of Examples 3 to 19, wherein the hollow tubular substrate element comprises at least two circumferentially extending rows of perforations around the hollow tubular substrate element.

[0332] Example 21: An aerosol generating article according to any one of Examples 3 to 20, wherein the hollow tubular substrate element comprises a maximum of five circumferentially extending rows of perforations around the hollow tubular substrate element.

[0333] Example 22: An aerosol generating article according to any one of Examples 19 to 21, wherein the circumferential rows of perforations are arranged circularly or helically around the hollow tubular substrate element.

[0334] Example 23: An aerosol generating article according to any one of Examples 20 to 22, wherein each circumferential row of perforations comprises from 8 to 30 perforations.

[0335] Example 24: An aerosol generating article according to any one of Examples 3 to 23, wherein the plurality of perforations comprises at least one perforation having a maximum dimension of at least about 200 micrometers or each of the plurality of perforations has a maximum dimension of at least about 200 micrometers.

[0336] Example 25: An aerosol generating article according to any one of Examples 3 to 24, wherein the plurality of perforations comprises at least one perforation having a maximum dimension of at most about 1 millimeter or each of the plurality of perforations has a maximum dimension of at most about 1 millimeter.

[0337] Example 26: An aerosol generating article according to any one of Examples 3 to 25, wherein the plurality of perforations comprises at least one perforation having an opening area of at least about 0.01 square millimeters or each of the plurality of perforations has an opening area of at least about 0.01 square millimeters.

[0338] Example 27: An aerosol generating article according to any one of Examples 3 to 26, wherein the plurality of perforations includes at least one perforation having an opening area of 1 square millimeter or less, or each of the plurality of perforations has an opening area of 1 square millimeter or less.

[0339] Example 28: An aerosol generating article according to any one of Examples 3 to 27, wherein the plurality of perforations has a total opening area of at least about 0.05 square millimeters.

[0340] Example 29: An aerosol generating article according to any one of Examples 3 to 28, wherein the plurality of perforations has a total opening area of at most about 30 square millimeters.

[0341] Example 30: An aerosol generating article according to any one of claims 3 to 29, wherein the hollow tubular substrate element has a ventilation level of at least about 5%.

[0342] Example 31: An aerosol generating article according to any one of Examples 3 to 30, wherein the hollow tubular substrate element has a ventilation level of at most about 60 percent.

[0343] Example 32: An aerosol generating article according to any one of Examples 3 to 31, wherein the rod of the aerosol generating substrate includes one or more susceptor elements disposed in contact with the hollow tubular substrate element.

[0344] Example 33: An aerosol generating article according to any one of Examples 1 to 33, wherein no outer wrapper and hollow tubular substrate element are attached.

[0345] Example 34: An aerosol generating article according to any one of Examples 2 to 33, wherein the rod of the aerosol generating substrate includes one or more protrusions extending across the empty space between the outer surface of the hollow tubular substrate element and the outer wrapper.

[0346] Example 35: An aerosol generating article according to Example 33 or Example 34, wherein one or more protrusions are integral with the hollow tubular substrate element.

[0347] Example 36: An aerosol generating article according to any one of Examples 33 to 35, wherein one or more protrusions are non-integral with the hollow tubular substrate element.

[0348] Example 37: An aerosol generating article according to Example 33, 34, or 36, wherein one or more protrusions are integral with the outer wrapper.

[0349] Example 38: An aerosol generating article according to any one of Examples 33 to 36, wherein one or more protrusions are non-integral with the outer wrapper.

[0350] Example 39: An aerosol generating article according to any one of Examples 33 to 36 and 38, wherein one or more protrusions are formed of homogenized tobacco material.

[0351] Example 40: An aerosol generating article according to any one of Examples 33 to 39, wherein one or more protrusions are arranged such that the empty spaces are discontinuous.

[0352] Example 41: An aerosol generating article according to any one of Examples 1 to 40, wherein the rod of the aerosol generating substrate includes an upstream element adjacent to the upstream end of the hollow tubular substrate element.

[0353] Example 42: An aerosol generating article according to Example 41, wherein the upstream element abuts against the upstream end of the hollow tubular substrate element.

[0354] Example 43: An aerosol generating article according to Example 41 or 42, wherein the outer wrapper surrounds at least a part of the hollow tubular substrate element and the upstream element.

[0355] Example 44: An aerosol generating article according to any one of Examples 41 to 43, wherein the upstream element is an upstream plug element.

[0356] Example 45: An aerosol generating article according to any one of Examples 41 to 44, wherein the outer diameter of the upstream element is substantially the same as the outer diameter of the aerosol generating article.

[0357] Example 46: An aerosol generating article according to any one of Examples 41 to 45, wherein the outer diameter of the upstream element is larger than the outer diameter of the hollow tubular substrate element.

[0358] Example 47: An aerosol generating article according to any one of Examples 41 to 46, wherein the outer diameter of at least a part of the hollow tubular substrate element is at least about 0.1 millimeter smaller than the outer diameter of the upstream element.

[0359] Example 48: An aerosol generating article according to any one of Examples 41 to 47, wherein the outer diameter of at least a part of the hollow tubular substrate element is at least about 6 millimeters smaller than the outer diameter of the upstream element.

[0360] Example 49: An aerosol generating article according to any one of Examples 41 to 48, wherein the upstream element has a length of about 2 millimeters to about 6 millimeters.

[0361] Example 50: An aerosol generating article according to any one of Examples 1 to 49, wherein the rod of the aerosol generating substrate comprises a downstream element adjacent to the downstream end of the hollow tubular substrate element.

[0362] Example 51: An aerosol generating article according to Example 50, wherein the downstream element is in contact with the downstream side end portion of the hollow tubular substrate element.

[0363] Example 52: An aerosol generating article according to Example 50 or 51, wherein the outer wrapper surrounds at least a part of the hollow tubular substrate element and the downstream element.

[0364] Example 53: An aerosol generating article according to any one of Examples 50 to 52, wherein the downstream element is a downstream side plug element.

[0365] Example 54: An aerosol generating article according to any one of Examples 50 to 53, wherein the outer diameter of the downstream element is substantially the same as the outer diameter of the upstream element and the outer diameter of the aerosol generating article.

[0366] Example 55: An aerosol generating article according to any one of Examples 50 to 54, wherein the outer diameter of the downstream element is larger than the outer diameter of the hollow tubular substrate element.

[0367] Example 56: An aerosol generating article according to any one of Examples 50 to 55, wherein the downstream element has a length of about 2 millimeters to about 15 millimeters.

[0368] Example 57: An aerosol generating article according to any one of Examples 1 to 56, wherein in the empty space, the outer surface of the hollow tubular substrate element and the outer wrapper are radially spaced apart by at least about 0.05 millimeters.

[0369] Example 58: An aerosol generating article according to any one of Examples 1 to 57, wherein in the empty space, the outer surface of the hollow tubular substrate element and the outer wrapper are radially spaced apart by at most about 3 millimeters.

[0370] Example 59: An aerosol generating article according to any one of Examples 1 to 58, wherein the outer wrapper has a basis weight of about 15 grams to about 100 grams per square meter.

[0371] Example 60: An aerosol generating article according to any one of Examples 1 to 59, wherein the basis weight of the outer wrapper is about 80 grams per square meter.

[0372] Example 61: An aerosol generating article according to any one of Examples 1 to 60, wherein the outer wrapper includes a plurality of perforations on the hollow tubular substrate element.

[0373] Example 62: An aerosol generating article according to Example 61, wherein the plurality of perforations of the outer wrapper are on the plurality of perforations of the hollow tubular substrate element.

[0374] Example 63: An aerosol generating article according to any one of Examples 1 to 62, wherein the rod of the aerosol generating substrate has a length of about 10 millimeters to about 40 millimeters.

[0375] Example 64: An aerosol generating article according to any one of claims 1 to 63, wherein the downstream section comprises at least one hollow tubular element.

[0376] Example 65: An aerosol generating article according to Example 64, wherein the ratio of the inner diameter of the hollow tubular substrate element to the inner diameter of the hollow tubular element of the downstream section is about 0.8 to 1.2.

[0377] Example 66: An aerosol generating article according to any one of Examples 1 to 65, wherein the downstream section consists of a mouthpiece element.

[0378] Example 67: An aerosol generating article according to any one of Examples 66, wherein the mouthpiece element includes at least one segment of a fibrous filter material.

[0379] Example 68: An aerosol generating article according to any one of Examples 1 to 67, wherein the downstream section includes a mouth-side end cavity at the downstream end.

[0380] Example 69: An aerosol generating article according to any one of Examples 1 to 68, wherein the downstream section has an overall length of about 15 millimeters to about 50 millimeters.

[0381] Example 70: An aerosol generating article according to any one of Examples 1 to 69, wherein the aerosol generating article has an overall length of about 35 millimeters to about 110 millimeters.

[0382] Example 71: An aerosol generating article according to any one of Examples 1 to 70, wherein the outer wrapper includes a plurality of perforations over an empty space.

[0383] Example 72: An aerosol generating article according to any one of Examples 1 to 71, wherein the empty space has a substantially annular cross-section.

[0384] Although for illustrative purposes only, the present invention will be further described with reference to the accompanying drawings.

[0385] The aerosol generating article 10 shown in FIG. 1 comprises a rod 12 of an aerosol generating substrate and a downstream section 14 provided downstream of the rod of the aerosol generating substrate 12. The aerosol generating article 10 extends from an upstream or distal end 16 that coincides with the upstream end of the aerosol generating substrate 12 to a downstream or mouth-side end 18 that coincides with the downstream end of the downstream section 14. The downstream section 14 comprises a hollow tubular element 20 and a mouthpiece element 50.

[0386] The aerosol generating article 10 has an overall length of about 55 millimeters and an outer diameter of about 7.2 millimeters.

[0387] The aerosol generating substrate 12 comprises a hollow tubular substrate element 40 formed of a homogenized tobacco material. The hollow tubular substrate element has a peripheral wall 42 that defines a longitudinal cavity 44 that provides an unrestricted flow channel through the hollow tubular substrate element 40. The upstream end of the longitudinal cavity 44 provides an air inlet through which air can be drawn into the aerosol generating article during use. The hollow tubular substrate element 40 has a length of about 12 millimeters.

[0388] The aerosol generating substrate also comprises an upstream plug element 70 of cellulose acetate tow that abuts the upstream end of the hollow tubular substrate element 40 and a downstream plug element 80 of cellulose acetate tow that abuts the downstream end of the hollow tubular substrate element 40. The upstream plug element 70 and the downstream plug element 80 each have a length of about 5 millimeters. The outer diameter of the upstream plug element 70 is substantially the same as the outer diameter of the downstream plug element 80 and substantially the same as the outer diameter of the aerosol generating article 10. The outer diameter of the hollow tubular substrate element 40 is smaller than the outer diameters of both the upstream plug element 70 and the downstream plug element 80.

[0389] The aerosol generating substrate also comprises an outer wrapper 60 surrounding a hollow tubular substrate element 40, an upstream plug element 70, and a downstream plug element 80. The outer wrapper 60 is arranged such that an empty space 90 is defined between the outer surface of the hollow tubular substrate element and the outer wrapper 60.

[0390] The hollow tubular substrate element 40 comprises two circumferential rows of perforations 46 providing fluid communication between the cavity 44 in the longitudinal axis direction of the hollow tubular substrate element 40 and the empty space 90 between the outer surface of the hollow tubular substrate element 40 and the outer wrapper 60. The perforations 46 are provided through the peripheral wall 42 of the hollow tubular substrate element 40.

[0391] The outer wrapper 60 also comprises two rows of perforations 66 which are above the row of perforations 46 within the hollow tubular substrate element 40.

[0392] The hollow tubular substrate element 40 does not substantially contribute to the overall RTD of the aerosol generating article. Accordingly, the RTD of the hollow tubular substrate element 40 is about 0 mmH2O.

[0393] The hollow tubular element 20 of the downstream section 14 is located immediately downstream of the hollow tubular substrate element 40 and the hollow tubular element 20 is longitudinally aligned with the aerosol generating substrate 12. The upstream end of the hollow tubular element 20 abuts against the downstream end of the hollow tubular substrate element 40.

[0394] The hollow tubular element 20 is provided in the form of a hollow cylindrical tube made of cellulose acetate tow. The hollow tubular element 20 defines an internal cavity 22 extending all the way from the upstream end of the hollow tubular element 20 to the downstream end of the hollow tubular element 20. The internal cavity 22 is substantially empty and thus substantially unrestricted air flow is possible along the internal cavity 22. The hollow tubular element 20 does not substantially contribute to the overall RTD of the aerosol generating article 10. Accordingly, the RTD of the hollow tubular element 20 is about 0 mmH2O.

[0395] As shown in FIG. 1, the inner diameter of the hollow tubular element 20 of the downstream section 14 is substantially the same as the inner diameter of the hollow tubular base element 40.

[0396] The mouthpiece element 50 extends from the downstream end of the hollow tubular element 20 to the downstream end or the mouth side end 18 of the aerosol generating article 10. The mouthpiece element 50 comprises a low density cellulose acetate filter segment. The mouthpiece element 50 can be individually wrapped by a plug wrap (not shown).

[0397] The article 10 comprises a tipping wrapper 52 surrounding the hollow tubular element 20 and the mouthpiece element 50. The tipping wrapper 52 is further located on the upstream portion of the downstream plug element 80 for joining the aerosol generating substrate 12 and the downstream section 14.

[0398] The aerosol generating article 10 is particularly suitable for use in an aerosol generating device comprising external heating means for externally heating the aerosol generating substrate 12. Thus, during use, it is preferred that the outer surface of the hollow tubular base element 40 is inserted into the heating cavity of the aerosol generating device in proximity to the heating element within the cavity. By heating the hollow tubular base element 40, an aerosol is generated from the homogenized tobacco material, which is released directly into the cavity 44 in the longitudinal direction of the hollow tubular base element 40 from the inner surface of the hollow tubular base element 40 and from the outer surface of the hollow tubular base element 40 into the empty space 90 defined between the outer wrapper 60 and the outer surface of the hollow tubular base element 40. When the consumer inhales on the aerosol generating article 10, the aerosol released into the empty space 90 is drawn in together with the air entering the empty space 90 through the plurality of perforations 46 of the hollow tubular base element 40 and through the plurality of perforations 66 of the outer wrapper 60 into the cavity 44 in the longitudinal direction of the hollow tubular base element 40. Air also enters the cavity 44 in the longitudinal direction of the hollow tubular base element 40 at the upstream end as the consumer inhales on the article 10. The combined air and aerosol is drawn through the aerosol generating article 10 and supplied to the consumer from the downstream end 18 of the aerosol generating article 10.

[0399] Figure 2 shows a part of an aerosol generation system 100 comprising an aerosol generator 102 and an aerosol article 110 according to a second embodiment of the present invention. The aerosol article 110 is shown in Figure 1 and is the same as that described above and has the same arrangement of similar components. However, the aerosol generation substrate further comprises a plurality of protrusions 140 extending across the empty space 90 between the outer surface of the hollow tubular substrate element 140 and the outer wrapper 160. The outer wrapper 160 is wrapped around the plurality of protrusions 148 and serves to hold the hollow tubular substrate element 140 in place and to hold the empty space 90 between the hollow tubular substrate element 140 and the outer wrapper 160. The plurality of protrusions 148 are physically separate from the hollow tubular substrate element 140 and are directly attached to the outer surface of the hollow tubular substrate element 140.

[0400] As shown in Figure 2, the aerosol generator 102 comprises a longitudinally extending heating cavity 104 for receiving the aerosol article 110. The heating cavity 104 has a closed distal end and an open mouth-side end. The air inlet 106 is installed at the distal end of the cavity such that air can be drawn through the aerosol article 110 during use. The heating cavity 104 comprises an external heating element 108 for resistively heating the aerosol generation substrate of the aerosol article 110 during use.

[0401] The aerosol generator 102 further comprises a power supply (not shown) and a control device (not shown) for controllably heating the aerosol article 110 during use when the aerosol article 110 is received within the device 102.

[0402] The specific embodiments and examples described above illustrate but do not limit the present invention. It is understood that other embodiments of the present invention may be made and that the specific embodiments and examples described herein are not exhaustive.

Claims

**Claim 1** An aerosol generating article comprising a rod of an aerosol generating substrate and a downstream section provided downstream of the rod of the aerosol generating substrate, wherein the rod of the aerosol generating substrate comprises a hollow tubular substrate element formed of a homogenized tobacco material and defining a longitudinal cavity providing an unrestricted flow channel through the hollow tubular substrate element, an outer wrapper surrounding the hollow tubular substrate element and arranged such that an empty space is defined between at least a part of the outer surface of the hollow tubular substrate element and the outer wrapper, the hollow tubular substrate element comprising a plurality of perforations providing fluid communication between the longitudinal cavity of the hollow tubular substrate element and the empty space between at least a part of the outer surface of the hollow tubular substrate element and the outer wrapper, the plurality of perforations of the hollow tubular substrate element being formed through the peripheral wall of the hollow tubular substrate element, the outer wrapper comprising a plurality of perforations overlying the hollow tubular substrate element, the aerosol generating article. **Claim 2** The aerosol generating article according to claim 1, wherein the hollow tubular substrate element comprises at least two rows of perforations extending circumferentially around the hollow tubular substrate element. **Claim 3** The aerosol generating article according to claim 1 or 2, wherein each of the plurality of perforations of the hollow tubular substrate element has an opening area of at least about 0.01 square millimeters. **Claim 4** The aerosol generating article according to any one of claims 1 to 3, wherein the hollow tubular substrate element has a wall thickness that is about 5 percent to about 40 percent of the outer diameter of the hollow tubular substrate element. **Claim 5** The aerosol generating article according to any one of claims 1 to 4, wherein, within the empty space, the outer surface of the hollow tubular substrate element and the outer wrapper are spaced apart radially by at least about 0.1 millimeters. **Claim 6** The aerosol generating article according to any one of claims 1 to 5, wherein the outer wrapper and the hollow tubular substrate element are not attached. **Claim 7** The aerosol generating article according to any one of claims 1 to 6, wherein the plurality of perforations of the outer wrapper are overlying the perforations within the hollow tubular substrate element. **Claim 8** The rod of the aerosol generating substrate further comprises an upstream plug element adjacent to the upstream end of the hollow tubular substrate element, and the outer wrapper surrounds at least a part of the hollow tubular substrate element and the upstream element. The aerosol generating article according to any one of claims 1 to 7.

9. The aerosol generating article according to claim 8, wherein at least a part of the hollow tubular substrate element has an outer diameter that is at least about 0.2 millimeters smaller than the outer diameter of the upstream plug element.

10. The aerosol generating article according to claim 8 or 9, wherein the rod of the aerosol generating substrate further comprises a downstream plug element adjacent to the downstream end of the hollow tubular substrate element and having the same outer diameter as the upstream plug element.

11. The aerosol generating article according to any one of claims 1 to 10, wherein the rod of the aerosol generating substrate comprises one or more protrusions extending across the empty space between the outer surface of the hollow tubular substrate element and the outer wrapper.

12. The aerosol generating article according to any one of claims 1 to 11, wherein the outer wrapper has a basis weight of at least about 80 grams per square meter.

13. The aerosol generating article according to any one of claims 1 to 12, wherein the hollow tubular substrate element is formed from two or more overlapping sheets of homogenized tobacco material.

14. The aerosol generating article according to any one of claims 1 to 13, wherein the downstream section comprises at least one hollow tubular element adjacent to the downstream end of the rod of the aerosol generating substrate.

15. The aerosol generating article according to any one of claims 1 to 14, wherein the downstream section comprises at least one mouthpiece filter element.

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