Aerosol generating devices, aerosol generating articles, and aerosol delivery systems

Abstract

The aerosol generating device (100) is configured for use in heating an aerosol-generating (200) article to generate an inhalable aerosol from an aerosol-forming substrate of the aerosol-generating article. The aerosol generating device comprises a housing (101). The housing (101) comprises a cavity (105) configured to receive the aerosol-generating article (200). The housing (101) is adapted to define a cooling airflow path extending from an exterior of the housing (101), through an interior of the housing (101), to an air-permeable portion of a wall (106) of the cavity (105). The wall (106) of the cavity (105) is tubular. The air-permeable portion of the wall of the cavity comprises at least one annular air-permeable band (112). The annular air-permeable band (112) is configured to direct airflow radially from the cooling airflow path into the cavity (105) around a periphery of the tubular wall (106) of the cavity (105).

Description

[Technical field]

[0001] The present disclosure relates to an aerosol generating device, an aerosol generating article for use with the aerosol generating device, and an aerosol delivery system formed from both the aerosol generating device and the aerosol generating article. [Background technology]

[0002] Aerosol-generating devices configured to generate an aerosol from an aerosol-forming substrate, such as a tobacco-containing substrate, are known in the art. Such known devices may generate an aerosol from a substrate by application of heat to the substrate, rather than by combustion of the substrate. The aerosol-forming substrate may be present as a component of an aerosol-generating article, where the aerosol-generating article is physically separate from the aerosol-generating device. In use, the aerosol-generating device may be received by the aerosol-generating article. The device may provide electrical power to enable transfer of heat from a heat source to the aerosol-forming substrate of the aerosol-generating article. During use of such known aerosol-generating devices and aerosol-generating articles, volatile compounds are released from the aerosol-forming substrate by heat transfer from the heat source and are entrained in the air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol, which is inhaled by the consumer. The transfer of heat to the aerosol-forming substrate to generate the aerosol may result in the aerosol emitted from the aerosol-forming substrate having a very high temperature, with the substrate being known in some known aerosol-generating articles to reach temperatures of about 270° C. when heated. Known aerosol-generating articles may require a complex arrangement of different components downstream of the substrate to cool the substrate to a level sufficient to avoid burning the user's mouth or throat. Summary of the Invention

[0003] The present disclosure is concerned with providing improvements in airflow management in aerosol generating devices and aerosol generating articles.

[0004] According to a first aspect of the present disclosure, there is provided an aerosol generating device configured for use in heating an aerosol-generating article to generate an inhalable aerosol from an aerosol-forming substrate of the aerosol-generating article. The aerosol generating device comprises a housing. The housing comprises a cavity configured to receive the aerosol-generating article. The housing is adapted to define a cooling airflow path extending from an exterior of the housing, through an interior of the housing, to an air permeable portion of a wall of the cavity.

[0005] Ambient air outside the device housing is likely to be cooler than within the housing when the device is operating. Thus, having a housing that defines a cooling airflow path extending from the outside of the housing provides a readily available source of ambient cooling air during use of the device. Providing a breathable portion in the wall of the cavity may allow the inflow of ambient cooling air received from the outside of the device to be directed through the cooling airflow path into the interior of the cavity. This may provide the beneficial effect of cooling the interior of the cavity. Furthermore, when the aerosol generating device is used in combination with an aerosol-generating article docked within the cavity, the cooling air received through the breathable portion of the wall of the cavity may be used to cool certain portions of the aerosol-generating article.

[0006] The aerosol generating device is preferably configured, for use with an aerosol-generating article docked within the cavity, such that an air permeable portion of the wall of the cavity matches a corresponding air permeable portion of the exterior wall of the aerosol-generating article. Matching the air permeable portion of the wall of the cavity of the aerosol generating device with the exterior wall of the aerosol-generating article allows efficient channeling of airflow from the cooling airflow path of the device into the interior of the aerosol-generating article.

[0007] As used herein, the term "breathable" is used in reference to an entity that allows air to pass through. The term "breathable" also encompasses the volumetric properties of a suitable material, for example a material that has porosity throughout all or a portion of the material's volume, in reference to either all or a portion of its volume.

[0008] As used herein, the term "match" is used to mean exactly or partially overlapping.

[0009] As used herein, the term "aerosol-generating device" is used to describe a device that interacts with an aerosol-forming substrate of an aerosol-generating article to generate an aerosol. The aerosol-generating device is preferably a smoking device that interacts with an aerosol-forming substrate of an aerosol-generating article to generate an aerosol that is inhalable directly through the user's mouth into the user's lungs. The aerosol-generating device may be a holder for a smoking article.

[0010] Preferably, the aerosol-generating article is a smoking article that generates an aerosol that is inhalable directly through the user's mouth into the user's lungs. More preferably, the aerosol-generating article is a smoking article that generates a nicotine-containing aerosol that is inhalable directly through the user's mouth into the user's lungs.

[0011] As used herein, the term "aerosol-forming substrate" means a substrate made of or including an aerosol-forming material capable of releasing volatile compounds upon heating to generate an aerosol.

[0012] Advantageously, the wall of the cavity may be tubular. The cavity may be provided with an open end and a closed end. The aerosol-generating device may be configured to receive the aerosol-generating article through the open end of the tubular cavity. Providing the device with a tubular cavity is particularly appropriate when the device is intended to be used with an aerosol-generating article that defines a rod form, with the tubular shape of the cavity corresponding to the geometric profile of such a rod. For example, when the aerosol-generating article is a smoking article, the use of a rod-shaped geometry in the article corresponds to the geometry of known smoking articles such as conventional cigarettes and electronic cigarettes.

[0013] As used herein, the term "rod" is used to mean a generally cylindrical element of substantially circular, oval, or elliptical cross-section.

[0014] The breathable portion of the cavity wall may comprise one or more of a porous material, a plurality of slits, a plurality of holes. By way of example and without limitation, the breathable portion of the cavity wall may be provided as a mesh, with mesh gaps defining openings in the mesh, thereby providing permeability for airflow through the mesh. Alternatively, the downstream end of the cooling airflow path may terminate in an open end, free of any mesh or other restriction, which is the breathable portion of the cavity wall, directing the cooling air from the cooling air path directly into the cavity. In a further alternative, the breathable portion of the cavity wall may comprise a plurality of voids, where the plurality of voids define voids in the material of the wall. The size of any voids, slits, or holes that may form part of the breathable portion of the cavity wall directly affects the permeability of the breathable portion to airflow. Thus, the size of any such voids, slits, or holes may be selected according to the desired volumetric flow rate of cooling air within the cavity of the aerosol generating device.

[0015] As used herein, the terms "upstream" and "downstream" are used to describe the relative position of an element or portion of an element of a heated aerosol-generating article with respect to the direction in which a user draws on the aerosol-generating article during use of the article.

[0016] Preferably, the cavity wall is tubular and the breathable portion of the cavity wall comprises at least one annular breathable band. Provision of the breathable portion of the cavity wall as one or more annular bands allows cooling air from the cooling airflow path to be directed radially into the cavity around the periphery of the tubular cavity wall. When the apparatus is used with an aerosol-generating article docked into the cavity, comprising an outer wall of the aerosol-generating article having a corresponding breathable portion provided as an annular band, matching alignment of the annular band of the apparatus with the annular band of the article may provide a uniform radial inflow of cooling air into the interior of the aerosol-generating article around the periphery of the outer wall of the article.

[0017] Advantageously, the at least one annular air permeability zone may include a first annular air permeability zone and a second annular air permeability zone. The first and second zones may be axially spaced apart from one another along the longitudinal axis of the cavity and have distinct first and second permeabilities to air flow through the zones. Providing the first and second annular air permeability zones with different permeabilities to air flow may enable correspondingly different flow rates through the first and second annular zones. This may in turn enable different levels of cooling to be achieved in different regions of the cavity.

[0018] Advantageously, the aerosol generating device may further comprise control electronics provided within the housing. The cooling airflow path may extend through or adjacent to the control electronics to provide cooling to the control electronics. In this way, cooling air from outside the housing may help to avoid overheating of the control electronics of the device.

[0019] The aerosol generating device preferably does not include any fan or similar means for forcing a flow of air from outside the housing of the device along the cooling airflow path. Rather, the flow of air from outside the housing along the cooling airflow path is instead preferably driven by a user applying suction to the mouth end of an aerosol-generating article docked in the cavity of the device. These features are discussed in more detail below with respect to the second aspect of the present disclosure defining an aerosol delivery system. However, in an alternative embodiment, the aerosol generating device may be configured to force a flow of air from outside the housing along the cooling airflow path towards a breathable portion of the wall of the cavity. By way of example, the device may include an electric fan provided within the housing for driving the flow of air along the cooling airflow path, the fan being provided with power from a power source provided within the device.

[0020] Conveniently, the aerosol generating device may be an electrical device for heating an aerosol-forming substrate of the aerosol-generating article by either or both of induction and resistance heating. The device may comprise a power source for providing electrical power. The power source is preferably a battery, thereby providing the device with the advantage of portability. The battery is preferably a rechargeable battery.

[0021] In one embodiment of the inductively heated version of the device, the wall of the cavity may comprise a susceptor portion. The susceptor portion may be axially spaced apart from the air permeable portion of the wall of the cavity along the longitudinal axis of the cavity. The aerosol generating device may further comprise an inductor coil surrounding the susceptor portion. Preferably, the inductor coil may surround the susceptor portion radially outside the susceptor portion. Locating the inductor coil radially outside the susceptor portion avoids the inductor coil being damaged from contact with the aerosol-generating article during insertion of the article into the cavity. In use, power supplied to the inductor coil (e.g. by the above-mentioned power supply of the device) causes the inductor coil to induce eddy currents in the susceptor portion. These eddy currents in turn cause the susceptor portion of the wall of the cavity to generate heat. As mentioned above, when an aerosol-generating article is docked in the cavity, heat generated in the cavity by the susceptor portion may be transferred to the article and heat an aerosol-forming substrate within the article to a temperature sufficient to cause an aerosol to emanate from the substrate. The susceptor portion is formed of a material capable of absorbing electromagnetic energy and converting it to heat. By way of example and without limitation, the susceptor portion may be formed of a ferromagnetic material, such as steel.

[0022] In a variation of the inductively heated version of the apparatus outlined above, the wall of the cavity may be devoid of any susceptor but still comprise an inductor coil surrounding the wall of the cavity. Preferably, the inductor coil may surround the wall of the cavity radially outward of the wall. Alternatively, the susceptor may be provided as part of the aerosol-generating article, and may preferably be wholly or partially enclosed within the aerosol-forming substrate of the aerosol-generating article.

[0023] In one embodiment of a resistively heated version of the device, the cavity may comprise a resistive heating element. The resistive heating element may be arranged to surround (in use) an aerosol-generating article docked in the cavity of the device. By way of example, the resistive heating element may have the form of an annular sleeve. The annular sleeve may be located in the wall of the cavity or may form part of the wall of the cavity. Alternatively, the resistive heating element may be arranged to be inserted (in use) into the interior of an aerosol-generating article docked in the cavity of the device, so as to be in close proximity to or in direct contact with the aerosol-forming substrate of the article. By way of example, the resistive heating element may have the form of a blade. In use, power is supplied to the resistive heating element (e.g. by the above-mentioned power supply of the device), which will result in heating of the heating element.

[0024] According to a second aspect of the present disclosure, there is provided an aerosol delivery system comprising an aerosol-generating article and an aerosol-generating device. The aerosol-generating article defines a rod. The rod contains an aerosol-forming substrate. An outer wall of the rod comprises a breathable portion. The breathable portion of the outer wall of the rod is located downstream of the aerosol-forming substrate. The device and article are configured such that when the aerosol-generating article is docked in the cavity, the breathable portion of the wall of the cavity coincides with the breathable portion of said outer wall of the rod. The aerosol-generating device may be as described above for any of the embodiments relating to the first aspect of the present disclosure.

[0025] In this second aspect of the disclosure, the matching alignment of the air-permeable portion of the cavity wall with the outer wall of the rod serves to facilitate efficient channeling of cooling air from the cooling airflow path of the apparatus into the interior of the aerosol-generating article.

[0026] The aerosol-forming substrate is preferably a solid aerosol-forming substrate. However, the aerosol-forming substrate may comprise both solid and liquid components. Alternatively, the aerosol-forming substrate may be a liquid aerosol-forming substrate.

[0027] Preferably the aerosol-forming substrate comprises nicotine. More preferably the aerosol-forming substrate comprises tobacco. Alternatively, or additionally, the aerosol-forming substrate may comprise a non-tobacco-containing aerosol-forming material.

[0028] Where the aerosol-forming substrate is a solid aerosol-forming substrate, the solid aerosol-forming substrate may comprise, for example, one or more of powders, granules, pellets, shreds, threads, strips, or sheets containing one or more of herb leaves, tobacco leaves, tobacco stems, expanded tobacco, and homogenized tobacco.

[0029] Optionally, the solid aerosol-forming substrate may contain tobacco or non-tobacco volatile flavour compounds, which are released upon heating of the solid aerosol-forming substrate. The solid aerosol-forming substrate may also contain one or more capsules, e.g., containing additional tobacco or non-tobacco volatile flavour compounds, which may melt during heating of the solid aerosol-forming substrate.

[0030] Optionally, the solid aerosol-forming substrate may be provided on or embedded in a thermally stable carrier. The carrier may take the form of a powder, granules, pellets, pieces, threads, strips, or sheets. The solid aerosol-forming substrate may be deposited on the surface of the carrier, for example in the form of a sheet, foam, gel, or slurry. The solid aerosol-forming substrate may be deposited on the entire surface of the carrier, or alternatively, in a pattern to provide a non-uniform flavor delivery during use.

[0031] In one preferred embodiment, the aerosol-forming substrate comprises a homogenized tobacco material. As used herein, the term "homogenized tobacco material" refers to a material formed by agglomerating particulate tobacco.

[0032] The aerosol-forming substrate preferably comprises an assembly of a sheet of homogenized tobacco material. As used herein, the term "sheet" refers to a layered element having a width and length substantially greater than its thickness. As used herein, the term "assembled" is used to describe a sheet that is rolled, folded, or otherwise compressed or clamped substantially transversely to the longitudinal axis of the aerosol-generating article.

[0033] The aerosol-forming substrate preferably comprises an aerosol former. As used herein, the term "aerosol former" is used to describe any suitable known compound or mixture of compounds that, in use, facilitates the formation of an aerosol and is generally resistant to thermal decomposition at the operating temperatures of the aerosol-generating article.

[0034] Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (such as propylene glycol, triethylene glycol, 1,3-butanediol, glycerin, etc.), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.). Preferred aerosol formers are polyhydric alcohols or mixtures thereof (such as propylene glycol, triethylene glycol, 1,3-butanediol, and most preferably glycerin).

[0035] The aerosol-forming substrate may comprise a single aerosol former, alternatively, the aerosol-forming substrate may comprise a combination of two or more aerosol formers.

[0036] Preferably, the aerosol-generating article may further comprise a first airflow path and a second airflow path. The rod has an oral end and a distal end, the oral end being located downstream of the distal end. The first airflow path may extend downstream along the interior of the rod through the aerosol-forming substrate towards the oral end, whereby upon application of suction at the oral end, air is drawn into the aerosol-generating article and passes through the aerosol-forming substrate along the interior of the rod downstream towards the oral end. The second airflow path may extend through a breathable portion of the exterior wall of the rod to supply the cooling airflow received from the cooling airflow path to a mixing region in the interior of the rod when the article is docked in the cavity of the device. The breathable portion and the mixing region may be located downstream of and immediately adjacent to the aerosol-forming substrate, whereby in use, the airflow along the second airflow path mixes with the aerosol flow along the first airflow path in the mixing region. By locating the breathable portion and the mixing area downstream and immediately adjacent to the aerosol-forming substrate, the air received from the cooling airflow path of the device and flowing along the second airflow path can efficiently cool any hot aerosol gas emanating from the heating of the aerosol-forming substrate and flowing along the first airflow path. Locating the breathable portion and the mixing area downstream and immediately adjacent to the aerosol-forming substrate may also ensure that the cooling air and the aerosol are efficiently mixed before reaching the mouth end of the rod. Efficient mixing of the cooling air and the aerosol in the rod of the aerosol-generating article is important in providing an enhanced experience to the user of the system. This efficient mixing of the cooling air and the aerosol is in contrast to conventional ventilated cigarettes, which introduce air into the cigarette through perforations provided far from the aerosol-forming substrate at or in close proximity to the mouth end of the cigarette. As a result, conventional ventilated cigarettes do not achieve complete and efficient mixing of the incoming ventilated air with the hot aerosol gas, which can result in a poor user experience.

[0037] Conveniently, the aerosol-forming substrate is located at the distal end or closer to the distal end than the oral end.

[0038] The interior of the rod is preferably free of obstacles from the mixing area to the mouth end, so that the mixed flow is not impeded when it flows from the mixing area to the mouth end during use. For example, the aerosol-generating article may lack a mouthpiece filter or an aerosol cooling element that impedes the downstream flow path toward the mouth end, as is commonly found in known electronic cigarettes. The lack of any such obstacles within the interior of the rod downstream of the aerosol-forming substrate may help to reduce the drawing resistance of the first and second airflow paths, and may also help to reduce the amount of suction that a user needs to apply at the mouth end to inhale a given amount of the mixed flow of aerosol and cooling air. Moreover, this may also help to reduce the complexity of manufacturing the aerosol-generating article.

[0039] The breathable portion of the rod's exterior wall may comprise one or more of a porous material, a plurality of slits, a plurality of holes. By way of example and without limitation, the breathable portion of the rod's exterior wall may be provided as a mesh, with mesh gaps defining openings in the mesh, thereby providing permeability for airflow through the mesh (i.e., through the exterior wall). In a further alternative, the breathable portion of the rod's exterior wall may comprise a plurality of voids, in which the plurality of voids define voids in the material of the exterior wall. The size of any voids, slits, or holes that may form part of the breathable portion of the rod's exterior wall directly affects the permeability of the breathable portion to airflow. The size of any such voids, slits, or holes may be selected according to the desired volumetric flow rate of cooling air within the interior of the aerosol-generating article.

[0040] The outer wall of the rod may be provided as a wrapper, which surrounds the aerosol-forming substrate. By way of example, the wrapper may be cigarette paper. The wrapper may be provided with perforations to form breathable portions of the outer wall of the rod. The wrapper preferably has a thickness of approximately 0.02 to 0.07 mm, or approximately 0.03 to 0.05 mm. The aerosol-generating article defined by the rod preferably has a diameter of approximately 3.7 to 9 mm, or approximately 5.7 to 7.9 mm. The aerosol-generating article may have an overall length of approximately 30 mm to approximately 100 mm. In a preferred embodiment, the aerosol-generating article has an overall length of approximately 45 mm.

[0041] The air permeable portion of the outer wall of the rod preferably comprises at least one annular air permeable zone. The use of the annular air permeable zone provides for uniform radial inflow of cooling air into the interior of the aerosol-generating article around the periphery of the article and improved mixing with the hot aerosol emitted from the aerosol-forming substrate.

[0042] Advantageously, the at least one breathability zone of the outer wall of the rod may include a first annular breathability zone and a second annular breathability zone. The first and second zones may be axially spaced apart from one another along the longitudinal axis of the rod and have distinct first and second permeabilities to airflow through the zones. Providing the first and second annular breathability zones with different permeabilities to airflow may enable correspondingly different flow rates through the first and second annular zones. This may in turn enable different levels of cooling to be achieved in different regions of the interior of the aerosol-generating article.

[0043] Preferably, the breathable portion of the outer wall of the rod may have an axial length of 0.2 to 4 millimeters, or more preferably 0.2 to 2.5 millimeters, or more preferably 0.2 to 1.8 millimeters, or more preferably 0.2 to 1.5 millimeters. Limiting the axial length of the breathable portion of the outer wall of the rod may help to concentrate the mixing of the cooling air received through the breathable portion and the aerosol emitted from the substrate to a narrow mixing region located downstream of the substrate.

[0044] Advantageously, the breathable portion of the outer wall of the rod may extend downstream of the aerosol-forming substrate by no more than 4 millimeters, or preferably no more than 2.5 millimeters, or more preferably no more than 1.8 millimeters, or more preferably no more than 1.5 millimeters, or more preferably no more than 0.2 millimeters. By restricting the breathable portion to extend downstream from the aerosol-forming substrate to no more than a certain distance, mixing of the cooling air received through the breathable portion with the aerosol emitted from the substrate can be achieved immediately downstream of the substrate. This helps to ensure that the user receives a thoroughly mixed inhalable vapor when the mixed flow reaches the mouth end of the rod, thereby enhancing the user's experience.

[0045] Advantageously, the article and the device may be configured such that upon application of suction to the mouth end with the article docked in the device, 50% to 90% of the combined volumetric flow along the first and second airflow paths flows through the breathable portion of the outer wall of the rod along the second airflow path. Advantageously, the article and the device may be configured such that upon application of suction to the mouth end with the article docked in the device, 55% to 75% of the combined volumetric flow along the first and second airflow paths flows through the breathable portion of the outer wall of the rod along the second airflow path. The proportion of the combined volumetric flow that flows along the second airflow path rather than the first airflow path is influenced by the degree of breathability of the breathable portion of the outer wall of the rod and the nature of the aerosol-forming substrate within the rod. For example, different aerosol-forming substrates present different draw resistances to the first airflow path, and draw resistance is also influenced by factors such as compaction of the substrate (e.g., when the substrate is a solid aerosol-forming substrate).

[0046] According to a third aspect of the present disclosure, there is provided an aerosol-generating article for use in an aerosol generating device. The aerosol-generating article defines a rod. The rod contains an aerosol-forming substrate and has a distal end and a mouth end, the mouth end being located downstream of the distal end. The aerosol-generating article comprises a first airflow path and a second airflow path. An outer wall of the rod comprises an air permeable portion, the air permeable portion of the outer wall of the rod being located downstream of the aerosol-forming substrate. The first airflow path extends through the aerosol-forming substrate along the interior of the rod downstream towards the mouth end, such that upon application of suction to the mouth end, air is drawn into the aerosol-generating article and passes through the aerosol-forming substrate along the interior of the rod downstream towards the mouth end. The second airflow path extends through the air permeable portion of the outer wall of the rod to supply cooling air from outside the rod to a mixing region inside the rod. The breathable portion and the mixing region are located together downstream and immediately adjacent to the aerosol-forming substrate, so that, in use, airflow along the second airflow path mixes with the aerosol flow along the first airflow path in the mixing region.

[0047] It will be appreciated that the aerosol-generating article of this third aspect is suitable for use with the aerosol-generating device of the first aspect discussed in the preceding paragraph and may also correspond to an aerosol-generating article forming part of the aerosol delivery system of the second aspect of the present disclosure.

[0048] By locating the breathable portion and the mixing area downstream and immediately adjacent to the aerosol-forming substrate, the air received through the breathable portion of the outer wall of the rod and flowing along the second airflow path may efficiently cool the hot aerosol emanating from the heating of the aerosol-forming substrate and flowing along the first airflow path. Locating the breathable portion and the mixing area downstream and immediately adjacent to the aerosol-forming substrate may also ensure that the cooled air and the aerosol are thoroughly mixed before reaching the mouth end of the rod. Efficient mixing of the cooled air and the aerosol within the rod of the aerosol-generating article is important in providing an enhanced experience to the user of the system. This efficient mixing of the cooled air and the aerosol is in contrast to conventional ventilated cigarettes, which introduce air into the cigarette through perforations provided far downstream from the aerosol-forming substrate at or in close proximity to the mouth end of the cigarette. Conventional ventilated cigarettes do not achieve efficient mixing of the incoming ventilation air with the hot aerosol gas, which can result in a poor user experience.

[0049] The aerosol-forming substrate is preferably located at the distal end of the rod or closer to the rod distal end than to the oral end of the rod.

[0050] The interior of the rod is preferably free of obstacles from the mixing area to the mouth end, so that the mixed flow is not impeded when it flows from the mixing area to the mouth end during use. As an example, the aerosol-generating article may lack a mouthpiece filter or an aerosol cooling element that impedes the downstream flow path toward the mouth end, as is commonly found in known electronic cigarettes. The lack of any such obstacles within the interior of the rod may help to reduce the drawing resistance of the first and second airflow paths, and may also help to reduce the amount of suction that a user needs to apply at the mouth end to inhale a given amount of the mixed flow of aerosol and cooling air. This may also reduce the complexity of manufacturing the article.

[0051] As described with respect to the aerosol delivery system of the second aspect of the present disclosure, the breathable portion of the outer wall of the rod may comprise one or more of a porous material, a plurality of slits, a plurality of holes. By way of example and without limitation, the breathable portion of the outer wall of the rod may be provided as a mesh, with mesh gaps defining openings in the mesh, thereby providing permeability for airflow through the mesh (i.e., through the outer wall of the rod). In a further alternative, the breathable portion of the outer wall of the rod may comprise a plurality of voids, in which the plurality of voids define voids in the material of the outer wall. The size of any voids, slits, or holes that may form part of the breathable portion of the outer wall of the rod directly affects the permeability of the breathable portion to airflow. The size of any such voids, slits, or holes may be selected according to the desired volumetric flow rate of cooling air within the interior of the aerosol-generating article.

[0052] Where the aerosol-generating article is a smoking article used to generate an inhalable aerosol directly into the user's lungs via the user's mouth, the outer wall of the rod may be provided as cigarette paper, the cigarette paper being provided with perforations to form breathable portions of the outer wall of the rod.

[0053] Again, as described with respect to the aerosol delivery system of the second aspect of the present disclosure, preferably the air-permeable portion of the outer wall of the rod may comprise at least one annular air-permeable zone. The use of an annular air-permeable zone provides for a uniform radial inflow of cooling air into the interior of the aerosol-generating article around the periphery of the article and improved mixing with the hot aerosol stream emanating from the aerosol-forming substrate.

[0054] Advantageously, the at least one annular breathability zone comprises a first annular breathability zone and a second annular breathability zone. The first and second zones may be axially spaced apart from one another along the longitudinal axis of the rod and have distinct first and second permeabilities to airflow through the zones. Providing the first and second annular breathability zones with different permeabilities to airflow may enable correspondingly different flow rates through the first and second annular zones. Accordingly, this may enable different levels of cooling to be achieved in different regions within the aerosol-generating article depending on whether those regions are adjacent to the first or second annular zones having their respective different permeabilities to airflow.

[0055] As described with respect to the aerosol delivery system of the second aspect of the present disclosure, preferably the breathable portion of the outer wall of the rod may have an axial length of 0.2 to 4 millimeters, or more preferably 0.2 to 2.5 millimeters, or more preferably 0.2 to 1.8 millimeters, or more preferably 0.2 to 1.5 millimeters. Limiting the axial length of the breathable portion of the outer wall of the rod may help to concentrate the mixing of the cooling air received through the breathable portion and the aerosol emitted from the substrate to a narrow area located downstream of the substrate.

[0056] As described with respect to the aerosol delivery system of the second embodiment, advantageously, the breathable portion of the outer wall of the rod may extend downstream of the aerosol-forming substrate by no more than 4 millimeters, or preferably no more than 2.5 millimeters, or more preferably no more than 1.8 millimeters, or more preferably no more than 1.5 millimeters, or more preferably no more than 0.2 millimeters. By restricting the breathable portion to extend downstream from the aerosol-forming substrate to no more than a certain minimum distance, mixing of the cooling air received through the breathable portion with the aerosol emitted from the substrate can be achieved immediately downstream of the substrate. This helps to ensure that the user receives a thoroughly mixed inhalable vapor when the mixed flow reaches the mouth end of the rod.

[0057] As described with respect to the aerosol delivery system of the second aspect of the present disclosure, advantageously, the article is configured such that, upon application of suction to the mouth end, 50%-90% of the combined volumetric flow along the first and second airflow paths flows through the breathable portion of the outer wall of the rod along the second airflow path. Advantageously, the article may be configured such that, upon application of suction to the mouth end of the aerosol-generating article, 55%-75% of the combined volumetric flow along the first and second airflow paths flows through the breathable portion of the outer wall of the rod along the second airflow path. The proportion of the combined volumetric flow that flows along the second airflow path rather than the first airflow path is influenced by the degree of breathability of the breathable portion of the outer wall of the rod and the nature of the aerosol-forming substrate within the rod. For example, different aerosol-forming substrates present different draw resistances to the first airflow path, and draw resistance is also influenced by factors such as compaction of the substrate (e.g., when the substrate is a solid aerosol-forming substrate).

[0058] The present invention is defined in the claims. However, below is provided 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 features of any other example, embodiment, or aspect described herein.

[0059] Example 1: An aerosol generating device configured for use in heating an aerosol-generating article to generate an inhalable aerosol from an aerosol-forming substrate of the aerosol-generating article, the aerosol generating device comprising a housing, the housing comprising a cavity configured to receive the aerosol-generating article, the housing adapted to define a cooling airflow path extending from an exterior of the housing, through an interior of the housing, to an air permeable portion of a wall of the cavity. Example 2: An aerosol generating device as described in Example 1, in which, in use with an aerosol-generating article docked within the cavity, the breathable portion of the wall of the cavity coincides with a corresponding breathable portion of the outer wall of the aerosol-generating article. Example 3: An aerosol generating device as described in any one of Examples 1 or 2, wherein the walls of the cavity are tubular, the cavity is provided with an open end and a closed end, and the aerosol generating device is configured to receive an aerosol-generating article through the open end of the tubular cavity. Example 4: An aerosol generating device according to any one of Examples 1 to 3, wherein the air-permeable portion of the wall of the cavity comprises one or more of a porous material, a plurality of slits, and a plurality of holes. Example 5: An aerosol generating device according to any one of Examples 1 to 4, wherein the wall of the cavity is tubular and the breathable portion of the wall of the cavity comprises at least one annular breathable zone. Example 6: An aerosol generating device as described in Example 5, wherein at least one annular breathable zone comprises a first annular breathable zone and a second annular breathable zone, the first zone and the second zone being axially spaced from one another along the longitudinal axis of the cavity and having distinct first and second permeabilities to airflow through the annular breathable zones. Example 7: An aerosol generating device as described in any one of Examples 1 to 6, further comprising a control electronics provided within the housing, and a cooling airflow path extending through or adjacent to the control electronics to provide cooling to the control electronics. Example 8: An aerosol generating device as described in any one of Examples 1 to 7, wherein the aerosol generating device is configured to force a flow of air from outside the housing along a cooling airflow path towards a breathable portion of the wall of the cavity. Example 9: An aerosol generating apparatus as described in any one of Examples 1 to 8, wherein the aerosol generating apparatus is an electrical device for heating an aerosol-forming substrate of the aerosol-generating article by either or both of induction heating and resistance heating, the device comprising a power source for supplying electrical power. Example 10: An aerosol generating device as described in Example 9, wherein the wall of the cavity comprises a susceptor portion, the susceptor portion being axially spaced from the air permeable portion of the wall of the cavity along the longitudinal axis of the cavity, and the aerosol generating device further comprises an inductor coil surrounding the susceptor portion. Example 11: An aerosol generating device as described in any one of Examples 9 or 10, wherein the device comprises a resistive heating element provided within the cavity and configured, in use, to surround or be inserted within an aerosol generating article docked within the cavity. Example 12: An aerosol delivery system comprising an aerosol generating device according to any one of Examples 1 to 11; and an aerosol-generating article, the aerosol-generating article defining a rod, the rod containing an aerosol-forming substrate, an outer wall of the rod having a breathable portion, the breathable portion of the outer wall of the rod being positioned downstream of the aerosol-forming substrate, the device and article being configured such that when the aerosol-generating article is docked within the cavity, the breathable portion of the wall of the cavity coincides with the breathable portion of the outer wall of the rod. Example 13: An aerosol delivery system as described in Example 12, wherein the aerosol-generating article further comprises a first airflow path and a second airflow path, the rod having an oral end and a distal end, the oral end being located downstream of the distal end, the first airflow path extending downstream along the interior of the rod through the aerosol-forming substrate towards the oral end, whereby upon application of suction at the oral end, air is drawn into the aerosol-generating article and passes downstream along the interior of the rod through the aerosol-forming substrate towards the oral end, and the second airflow path extending through an air-permeable portion of an outer wall of the rod when the article is docked in the cavity of the device to supply cooled airflow received from the cooled airflow path to a mixing region within the rod, the air-permeable portion, and a mixing region located downstream of and immediately adjacent to the aerosol-forming substrate, whereby in use the airflow along the second airflow path mixes with the aerosol flow along the first airflow path in the mixing region. Example 14: An aerosol delivery system as described in Example 13, wherein the aerosol-forming substrate is located at the distal end or closer to the distal end than to the oral end. Example 15: An aerosol delivery system as described in either Example 13 or Example 14, wherein the interior of the rod is free of obstacles from the mixing region to the mouth end, such that in use, the mixed flow is not impeded as it flows from the mixing region to the mouth end. Example 16: An aerosol delivery system described in any one of Examples 12 to 15, wherein the breathable portion of the outer wall of the rod comprises one or more of a porous material, a plurality of slits, and a plurality of holes. Example 17: An aerosol delivery system described in any one of Examples 12 to 16, wherein the breathable portion of the outer wall of the rod comprises at least one annular breathable zone. Example 18: An aerosol delivery system as described in Example 17, wherein at least one breathable zone of the outer wall of the rod comprises a first annular breathable zone and a second annular breathable zone, the first zone and the second zone being axially spaced from one another along the longitudinal axis of the rod and having distinct first and second permeabilities to airflow through the annular breathable zone. Example 19: An aerosol delivery system described in any one of Examples 12 to 18, wherein the breathable portion of the outer wall of the rod has an axial length of 0.2 to 4 millimeters, or 0.2 to 2.5 millimeters, or 0.2 to 1.8 millimeters, or 0.2 to 1.5 millimeters. Example 20: An aerosol delivery system described in any one of Examples 12 to 19, wherein the breathable portion of the outer wall of the rod extends downstream of the aerosol-forming substrate by no more than 4 millimeters, or no more than 2.5 millimeters, or no more than 1.8 millimeters, or no more than 1.5 millimeters, or no more than 0.2 millimeters. Example 21: An aerosol delivery system described in any of Examples 13-20, wherein the aerosol-generating article and the aerosol-generating device are configured such that upon application of suction to the oral end with the article docked in the device, 50% to 90% of the combined volumetric flow along the first airflow path and the second airflow path flows through the breathable portion of the outer wall of the rod along the second airflow path. Example 22: An aerosol delivery system as described in Example 21, wherein the aerosol-generating article and the aerosol-generating device are configured such that upon application of suction to the oral end with the article docked within the device, 55% to 75% of the combined volumetric flow along the first airflow path and the second airflow path flows through the breathable portion of the outer wall of the rod along the second airflow path. Example 23: An aerosol-generating article for use in an aerosol-generating device, the aerosol-generating article defining a rod, the rod containing an aerosol-forming substrate and having an oral end and a distal end, the oral end being located downstream of the distal end, the aerosol-generating article comprising a first airflow path and a second airflow path, an exterior wall of the rod comprising a breathable portion, the breathable portion of the exterior wall of the rod being located downstream from the aerosol-forming substrate, the first airflow path extending downstream towards the oral end along an interior of the rod and through the aerosol-forming substrate, whereby An aerosol-generating article, wherein upon application of suction to the mouth end, air is drawn into the aerosol-generating article and passes along the interior of the rod downstream towards the mouth end through the aerosol-forming substrate, and a second airflow path extends through an air-permeable portion of the exterior wall of the rod to supply a cooling airflow from outside the rod to a mixing region within the interior of the rod, the air-permeable portion, and a mixing region located downstream of and immediately adjacent to the aerosol-forming substrate, whereby, in use, the airflow along the second airflow path mixes with the aerosol flow along the first airflow path in the mixing region. Example 24: An aerosol-generating article as described in example 23, wherein the aerosol-forming substrate is located at the distal end of the rod or closer to the distal end of the rod than to the oral end of the rod. Example 25: An aerosol delivery system as described in either Example 23 or Example 24, wherein the interior of the rod is free of obstacles from the mixing region to the mouth end, such that in use, the mixed flow is not impeded as it flows from the mixing region to the mouth end. Example 26: An aerosol-generating article described in any one of Examples 22 to 25, wherein the breathable portion comprises one or more of a porous material, a plurality of slits, and a plurality of holes. Example 27: An aerosol-generating article according to any one of Examples 23 to 26, wherein the breathable portion of the outer wall of the rod comprises at least one annular breathable zone. Example 28: An aerosol-generating article as described in Example 27, wherein at least one annular ventilation zone comprises a first annular ventilation zone and a second annular ventilation zone, the first zone and the second zone being axially spaced from each other along the longitudinal axis of the rod and having distinct first and second permeabilities to airflow through the annular ventilation zones. Example 29: An aerosol-generating article described in any one of Examples 23 to 28, wherein the breathable portion of the outer wall of the rod has an axial length of 0.2 to 4 mm, or 0.2 to 2.5 mm, or 0.2 to 1.8 mm, or 0.2 to 1.5 mm. Example 30: An aerosol-generating article described in any one of Examples 23 to 29, wherein the breathable portion of the outer wall of the rod extends downstream of the aerosol-forming substrate by no more than 4 millimeters, or no more than 2.5 millimeters, or no more than 1.8 millimeters, or no more than 1.5 millimeters, or no more than 0.2 millimeters. Example 31: An aerosol-generating article described in any of Examples 23-30, wherein the article is configured such that upon application of suction to the mouth end, 50% to 90% of the combined volumetric flow along the first airflow path and the second airflow path flows through the breathable portion of the outer wall of the rod along the second airflow path. Example 32: An aerosol-generating article as described in Example 31, wherein the article is configured such that upon application of suction to the mouth end, 55% to 75% of the combined volumetric flow along the first airflow path and the second airflow path flows through the breathable portion of the outer wall of the rod along the second airflow path.

[0060] The embodiments will now be further described with reference to the following figures: [Brief description of the drawings]

[0061] [Figure 1] FIG. 1 illustrates a perspective view of an aerosol generating device according to the present disclosure. [Diagram 2] FIG. 2 illustrates a further perspective view of the aerosol generating device of FIG. 1, but with a portion of the device's housing removed to allow viewing of the interior of the device. [Diagram 3] FIG. 3 corresponds to the view of FIG. 2, but with an aerosol-generating article coupled to an aerosol generating device to provide an aerosol delivery system. [Figure 4] FIG. 4 illustrates a perspective view of the aerosol-generating article shown in FIG. [Figure 5a-5c] 5a, 5b, and 5c illustrate three different side elevational views of the aerosol-generating article of FIG. [Figure 6a-6b] Figures 6a and 6b relate to a second embodiment and show a detailed view of a) a portion of the cavity wall of the device and b) a portion of the external wall of the article. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] 1 shows an aerosol generating device 100. The device 100 has a housing 101. An activation button 102 is integrated into the housing 101.

[0063] 2, a power source in the form of a rechargeable battery 103 is located within the housing 101. Control electronics 104 are also located within the housing 101. The control electronics 104 are positioned adjacent to the rechargeable battery 103. The housing 101 has a tubular cavity 105 extending into the interior of the device 100. The cavity 105 is defined by a tubular wall 106 that extends into the device 100 along a longitudinal axis 107. The cavity 105 has an open end 108 and a closed end 109, the open end and the closed end being located at opposite ends of the cavity. The housing 101 is provided with a slidable cover 110 that can be moved to expose or close the open end 108 of the cavity 105.

[0064] As shown in Figures 2 and 3, the tubular wall 106 has a lower portion 106a and an upper portion 106b. The lower portion 106a is formed of a material different from the upper portion 106b. The lower portion 106a is formed of a material capable of absorbing electromagnetic energy and converting it into heat. Therefore, in this embodiment, the lower portion 106a is a susceptor portion. Accordingly, the terms lower portion and susceptor portion are used interchangeably with reference numeral 106a. In this example, the susceptor portion 106a is formed of steel. However, in other embodiments (not shown), the susceptor portion 106a may be formed of other materials capable of absorbing electromagnetic energy and converting it into heat. The inductor coil 111 circumferentially surrounds the susceptor portion 106a. The upper portion 106b of the tubular wall 106 is formed of a polymeric material. An annular region of the upper portion 106 b of the tubular wall 106 of the cavity 105 is provided with a uniform distribution of holes extending radially through the tubular wall to form an annular breathable zone 112 .

[0065] 2 and 3, a row of air inlets 113 is provided in the bottom surface of the housing 101, and a circular arrangement of air inlets 114 is provided in the side wall of the housing 101. Air entering the housing 101 through the air inlets 113, 114 flows through the interior of the housing and is in fluid communication with the annular breathable band 112, as shown by the fluid flow lines in FIG.

[0066] 3, a single air inlet 115 is also provided in the bottom surface of the housing 101 directly beneath the closed end 109 of the cavity 105, with a fluid flow channel extending from the air inlet 115 to an opening (not shown) formed in the closed end 109 of the cavity 105. Fluid flow lines are included in FIG. 3 showing how air entering through the air inlet 115 is in fluid communication with the closed end 109 of the cavity 105.

[0067] 3, the aerosol-generating article 100 is used in conjunction with an aerosol-generating device 200. The aerosol-generating device 100 and the aerosol-generating article 200 together form an aerosol delivery system 300.

[0068] 4, the aerosol-generating article 200 has the form of an elongated cylindrical rod. Accordingly, the terms aerosol-generating article and rod are used interchangeably herein with reference to the reference numeral 200. The aerosol-generating article 200 has a diameter d of approximately 3.7 to 9 millimeters. 200 However, in an alternative embodiment, the diameter d 200 is approximately 5.7 to 7.9 millimeters. The aerosol-generating article 200 has a distal end 201 and an oral end 202. The aerosol-generating article 200 has a cigarette paper wrapper 203. The wrapper 203 forms the outer wall of the rod 200. As shown in Figures 5b and 5c, the porous forward plug 204, the plug of aerosol-forming substrate 205, and the tubular core element 206 are assembled sequentially and coaxially within the wrapper 203. The porous forward plug 204 is located at the distal end 201. The plug of aerosol-forming substrate 205 is positioned immediately downstream of the forward plug 204. The tubular core element 206 is positioned immediately downstream of the plug of aerosol-forming substrate 205 and extends downstream towards the oral end 202. In the embodiment shown, the hollow interior 207 of the tubular core element 206 is free of obstructions such as a mouthpiece filter element to define an empty space. The hollow interior 207 therefore means that the interior of the rod 200 between the downstream end of the aerosol-forming substrate 205 and the mouth end 202 defines an unobstructed flow path. However, in an alternative embodiment (not shown), a filter element may be located within the rod 200 adjacent the mouth end 202. For the embodiment shown and described herein, the aerosol-forming substrate 205 is a solid substrate containing tobacco. The annular region of the wrapper 203 is provided with a uniform distribution of holes extending radially through the tubular wall to form an annular breathability zone 208 within the wrapper 203 (i.e., the outer wall) of the rod 200.

[0069] A first airflow path 209 extends through the aerosol-forming substrate 205 and along the hollow interior 207 of the tubular core element 206. A second airflow path 210 extends through the annular breathable zone 208 to a mixing region 211 located within the rod 200. The mixing region 211 is where the first airflow path 209 and the second airflow path 210 coincide and their respective fluid flows intermix and combine, as described in more detail below.

[0070] The aerosol-generating article 200 shown in the figures and described herein is a smoking article intended for use in an aerosol-generating device 100 to generate an aerosol from an aerosol-forming substrate 205 for inhalation by a user. While the aerosol-generating device 100 is reusable, the aerosol-generating article 200 is disposable and intended for single use only.

[0071] In use, a user would first slide the slidable cover 110 aside to expose the open end 108 of the cavity 105. The user would then insert a new, unused aerosol-generating article 200 into the cavity 105 via the open end 108 until the distal end 201 of the article touches the closed end 109 of the cavity. In this position, the aerosol-generating article 200 is said to be docked into the cavity 105 of the aerosol-generating device 200. The combination of the aerosol-generating device 100 and the aerosol-generating article 200 forms an aerosol delivery system 300. When the aerosol-generating article 200 is docked in the cavity 105, the annular breathability zone 112 of the tubular wall 106 of the cavity 105 coincides with the annular breathability zone 208 of the wrapper 203 of the aerosol-generating article 200. Furthermore, when the aerosol-generating device 200 is docked in the cavity 105 , the plug of the aerosol-forming substrate 205 is located entirely within the susceptor portion 106 a and the inductor coil 111 .

[0072] As the user presses the activation button 102, the control electronics 104 controls the supply of power from the rechargeable battery 103 to the inductor coil 111. The resulting current flow through the inductor coil 111 induces eddy currents in the steel susceptor portion 106a. These eddy currents in turn result in heating of the susceptor portion 106a. Heat from the susceptor portion 106a is radiated onto the aerosol-generating article 200 contained within the cavity 105. Because the plug of the aerosol-forming substrate 205 is located entirely within the susceptor portion 106a and the inductor coil 111, heat from the susceptor portion is radiated onto the wrapper 203 of the aerosol-generating article 200 and conducted to the plug of the aerosol-forming substrate 205. The resulting heating of the aerosol-forming substrate 205 causes the substrate to emit an aerosol.

[0073] The control electronics 104 are configured to regulate the temperature of the susceptor portion 106a according to a predetermined thermal profile. Once the susceptor portion 106a reaches a temperature high enough to generate an aerosol from the plug of aerosol-forming substrate 205, the user may then suck on the mouth end 202 of the aerosol-generating article 200 to apply suction to the mouth end. Each suck taken by the user on the aerosol-generating article 200 is commonly referred to as a "puff."

[0074] Suction resulting from a user sucking on the mouth end 202 causes air to be drawn into the aerosol-generating device 100 via the inlet opening 115 and carried through the closed end 109 of the cavity 105. The suction causes this air to flow along a first airflow path 209 by entering the aerosol-generating article 200 through the porous front plug 204 and forward through the plug of the aerosol-forming substrate 205. This air becomes entrained with aerosol emitted by the aerosol-forming substrate 205 due to heating by the susceptor portion 106a and continues to flow along the first airflow path 209 to emerge from the downstream end of the plug of the aerosol-forming substrate 205 into a mixing region 211.

[0075] The suction provided by the user sucking on the oral end 202 also causes outside air to be drawn into the housing 101 of the aerosol generating device 100 via the air inlets 113, 114. This air then flows past the battery 103 and the control electronics 104 within the interior of the housing 101, thereby serving to cool both the battery 103 and the control electronics 104. This air then flows forward to and through an annular breathable zone 112 defined in the upper portion 106b of the tubular wall 106 of the cavity 105. The matching alignment of the annular breathability zone 112 defined in the tubular wall 106 of the cavity 105 of the device 100 with the annular breathability zone 208 defined in the wrapper 203 of the aerosol-generating article 200 results in a majority of the air flowing through the breathability zone 112 and then passing along a second airflow path 210 across the radial gap separating the tubular wall 106 and the article 200 and through the breathability zone 208. In this manner, external air can be delivered through the interior of the housing 101 of the aerosol-generating device 100 to provide cooling to the battery 103 and the control electronics 104 and then into the aerosol-generating article 200 docked in the cavity 105. Upon passing through the annular breathability zone 208 defined in the wrapper 203 of the article 200, the external air enters a mixing region 211.

[0076] In the mixing region 211, the heated aerosol flowing along the first airflow path 209 mixes with the cooled outside air flowing along the second airflow path 210, resulting in cooling of the aerosol. The cooled mixed air then flows downstream along the hollow interior 207 of the tubular core element 206 towards the mouth end 202 to be inhaled by the user.

[0077] In the illustrated aerosol-generating article 200, the annular breathable zone 208 has an axial length L 208 , with the upstream end of the annular band 208 approximately coinciding with the downstream end of the plug of aerosol-forming substrate 205. In an alternative embodiment, the axial length L 208may be as little as 0.2 millimeters. The aerosol-generating article 200 shown in the figures may have a length of between approximately 30 millimeters and approximately 100 millimeters.

[0078] In an alternative embodiment, as shown in FIG. 6a, the annular breathable zone 112 of the tubular wall 106 of the cavity 105 of the aerosol generating device 100 is formed of two annular zones, a first annular zone 112a and a second annular zone 112b. FIG. 6a shows region "A" (see FIG. 3) of the tubular wall 106. The first annular zone 112a and the second annular zone 112b are axially spaced apart from each other along the longitudinal axis 107, with the first annular zone 112a being closer to the closed end 109 of the cavity 105 than the second annular zone 112b. However, the first annular zone 112a and the second annular zone 112b have distinct (i.e., different) levels of permeability to airflow through the annular zones. In the embodiment shown in FIG. 6a, both the annular zone 112a and the annular zone 112b are provided with a uniform arrangement of holes extending through the tubular wall 106. However, the holes in the first annular zone 112a are larger in area than the holes in the second annular zone 112b. This difference in hole area has the effect that, in use, a larger volumetric flow of external cooling air flows through the first annular zone 112a than through the second annular zone 112b. This difference in volumetric flow rate provides differential cooling along the length or axis 107 of the cavity 105. To complement the first annular zone 112a and the second annular zone 112b provided on the tubular wall 106 of the aerosol-generating device 100, the annular breathability zone 208 of the wrapper 203 of the aerosol-generating article 200 is similarly formed of two annular zones, namely a first annular zone 208a and a second annular zone 208b (as shown in FIG. 6b). FIG. 6b shows region "B" (see FIG. 4) of the wrapper 203 of the aerosol-generating article 200. The first annular band 208a and the second annular band 208b are axially spaced apart from one another along the length of the article 200, with the first annular band 208a being closer to the distal end 201 of the article 200 than the second annular band 208b. However, the first annular band 208a and the second annular band 208b have distinct (i.e., different) levels of permeability to airflow therethrough. In the embodiment shown in FIG. 6b, both the annular band 208a and the annular band 208b are provided with a uniform arrangement of holes extending through the wrapper 203. However, the holes in the first annular band 208a are larger in area than the holes in the second annular band 208b.This difference in hole area has the effect that, in use, a greater volumetric flow of air flows through the first annular zone 208a than through the second annular zone 208b. This difference in volumetric flow rates provides differential cooling within the interior of the article 200 along the length of the article, with a higher level of cooling air being introduced closer to the aerosol-forming substrate, but immediately downstream, i.e., via the first annular zone 208a. The first annular zone 112a, 208a and the second annular zone 112b, 208b of the apparatus 100 and article 200 are arranged such that, when the article is docked in the cavity 105 of the apparatus, the first annular zone 112a of the apparatus coincides with the first annular zone 208a of the article, and the second annular zone 112b of the apparatus coincides with the second annular zone 208b of the article. 6a and 6b, the first annular bands 112a, 208a are of equal length and completely overlap one another, and similarly, the second annular bands 112b, 208b are of equal length and completely overlap one another. However, in a further alternative embodiment (not shown), the first annular bands 112a, 208a may instead only partially overlap, and similarly, the second annular bands 112b, 208b may instead only partially overlap.

[0079] As an alternative to the use of different hole sizes in the first annular zone 112a, 208a and the second annular zone 112b, 208b, different air permeabilities in the first zone and the second zone may instead be provided by the use of different hole densities in the first zone and the second zone, or by the use of materials having different porosities for the first zone and the second zone.

[0080] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like, should be understood in all instances as modified by the term "about." Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number "A" is understood as "A" ± 10%. Within this context, the number "A" may be considered to include a numerical value that is within the general standard error for the measurement of the property that the number "A" modifies. The number "A" may, in some cases as used in the appended claims, deviate by the percentages recited above, provided that the amount by which "A" deviates does not materially affect the basic and novel property(ies) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. 1. An aerosol generating apparatus configured for use in heating an aerosol-generating article to generate an inhalable aerosol from an aerosol-forming substrate of the aerosol-generating article, comprising: the aerosol generating device comprises a housing; the housing comprises a cavity configured to receive the aerosol-generating article; the housing is adapted to define a cooling airflow path extending from an exterior of the housing, through an interior of the housing, to an air permeable portion of a wall of the cavity; An aerosol generating device, wherein the wall of the cavity is tubular, and the air-permeable portion of the wall of the cavity comprises at least one annular air-permeable band, the annular air-permeable band being configured to direct airflow radially from the cooling airflow path into the cavity around a periphery of the tubular wall of the cavity.

2. 2. The aerosol generating device of claim 1, wherein an aerosol-generating article is docked into the cavity, and the breathable portion of the wall of the cavity coincides with a corresponding breathable portion of an outer wall of the aerosol-generating article.

3. 3. The aerosol generating device of claim 1 or 2, wherein the wall of the cavity is tubular, the cavity is provided with an open end and a closed end, and the aerosol generating device is configured to receive the aerosol-generating article through the open end of the tubular cavity.

4. The air permeable portion of the wall of the cavity A porous material; A plurality of slits; The aerosol generating device according to any one of claims 1 to 3, further comprising one or more of:

5. 5. An aerosol generating device as described in any one of claims 1 to 4, wherein the at least one annular air permeability zone comprises a first annular air permeability zone and a second annular air permeability zone, the first and second zones being axially spaced from one another along the longitudinal axis of the cavity and having distinct first and second permeabilities to airflow through the annular air permeability zones.

6. An aerosol generating device as described in any one of claims 1 to 5, wherein the aerosol generating device is configured to force a flow of air from outside the housing along the cooling airflow path towards the breathable portion of the wall of the cavity.

7. 1. An aerosol delivery system comprising: An aerosol generating device according to any one of claims 1 to 6, an aerosol-generating article defining a rod, said rod containing an aerosol-forming substrate, an outer wall of said rod comprising a breathable portion, said breathable portion of said outer wall of said rod being positioned downstream of said aerosol-forming substrate; and an article configured such that when the aerosol-generating article is docked within the cavity, the breathable portion of the wall of the cavity coincides with the breathable portion of the outer wall of the rod.

8. the aerosol-generating article further comprising a first airflow path and a second airflow path; the rod having an oral end and a distal end, the oral end being downstream from the distal end; the first airflow path extends downstream towards the mouth end along an interior of the rod and through the aerosol-forming substrate, such that upon application of suction at the mouth end, air is drawn into the aerosol-generating article and downstream towards the mouth end along the interior of the rod and through the aerosol-forming substrate; 8. The aerosol delivery system of claim 7, wherein the second airflow path extends through the breathable portion of the outer wall of the rod when the article is docked in the cavity of the device to supply cooled airflow received from the cooled airflow path to a mixing region within the rod, the breathable portion, and the mixing region located downstream and immediately adjacent to the aerosol-forming substrate, whereby, in use, the airflow along the second airflow path mixes with the aerosol flow along the first airflow path in the mixing region to provide a mixed flow.

9. The air permeable portion of the outer wall of the rod A porous material; A plurality of slits; 9. The aerosol delivery system of claim 7 or 8, comprising one or more of:

10. 1. An aerosol-generating article for use in an aerosol generating device, the aerosol-generating article defining a rod, the rod containing an aerosol-forming substrate and having a distal end and an oral end, the oral end being located downstream of the distal end; the aerosol-generating article comprising a first airflow path and a second airflow path; an outer wall of the rod having a breathable portion, the breathable portion of the outer wall of the rod being positioned downstream of the aerosol-forming substrate; the first airflow path extends along an interior of the rod and through the aerosol-forming substrate downstream towards the mouth end, such that upon application of suction to the mouth end, air is drawn into the aerosol-generating article and through the aerosol-forming substrate along the interior of the rod downstream towards the mouth end; the second airflow path extends through the air permeable portion of the outer wall of the rod to supply cooling air from outside the rod to a mixing region within the rod, to the air permeable portion, and to the mixing region located downstream of and immediately adjacent to the aerosol-forming substrate, whereby, in use, airflow along the second airflow path mixes in the mixing region with the aerosol flow along the first airflow path; the air-permeable portion of the outer wall of the rod comprises at least one annular air-permeable zone, the at least one annular air-permeable zone comprising a first annular air-permeable zone and a second annular air-permeable zone, the first zone and the second zone being axially spaced from one another along a longitudinal axis of the rod and having distinct first and second permeabilities to air flow through the annular air-permeable zones.

11. 11. The aerosol-generating article of claim 10, wherein the aerosol-forming substrate is located at the distal end of the rod or closer to the distal end of the rod than to the oral end of the rod.

12. 12. The aerosol-generating article of claim 10 or 11, wherein the interior of the rod is free of obstructions from the mixing region to the mouth end, such that, in use, the mixed flow is unimpeded as it flows from the mixing region to the mouth end.

13. The breathable portion is A porous material; A plurality of slits; A plurality of holes.

14. 14. An aerosol-generating article according to any one of claims 10 to 13, wherein the breathable portion of the outer wall of the rod has an axial length of from 0.2 to 4 mm, or from 0.2 to 2.5 mm, or from 0.2 to 1.8 mm, or from 0.2 to 1.5 mm.

15. 15. An aerosol-generating article according to any one of claims 10 to 14, wherein the breathable portion of the outer wall of the rod extends downstream of the aerosol-forming substrate by no more than 4 millimeters, or by no more than 2.5 millimeters, or by no more than 1.8 millimeters, or by no more than 1.5 millimeters, or by no more than 0.2 millimeters.

Images