Aerosol-generating article

Abstract

There is provided an aerosol-generating article for use with an aerosol-generating device to generate an aerosol. The aerosol-generating article has a length extending in an x direction, a width extending in a y direction and a height extending in a z direction, the height being less than each of the length and the width. The aerosol-generating article comprises a cavity extending in a downstream direction between an air inlet and an air outlet. The cavity comprises successively arranged upstream and downstream portions. The air inlet forms part of the upstream portion and the air outlet forms part of the downstream portion. The transverse cross-sectional area of the downstream portion of the cavity is less than the transverse cross-sectional area of the upstream portion of the cavity, with the volume of the downstream portion of the cavity being less than the volume of the upstream portion of the cavity. Aerosol-forming substrate is arranged in both upstream and downstream portions of the cavity.

Description

[0001] AEROSOL-GENERATING ARTICLE

[0002] The present disclosure relates to an aerosol-generating article comprising an aerosolforming substrate.

[0003] A typical aerosol-generating article may appear similar to a conventional cigarette. For example, such an aerosol-generating article may be substantially cylindrical and comprise an aerosol-forming substrate and other components such as a mouthpiece filter element and a cooling element, all arranged together in the form of a rod and wrapped in a cigarette paper. Dimensions of such typical aerosol-generating articles are often similar to the dimensions of conventional cigarettes. Cylindrical aerosol-generating articles having a corresponding cylindrical aerosol-forming substrate may be used in conjunction with electrically operated aerosolgenerating devices, the device operable to heat the aerosol-forming substrate of the article. However, a significant period of time is required for pre-heating the aerosol-forming substrate across the cylindrical transverse cross-section of the substrate to a temperature sufficient to vaporise desired volatile compounds of the substrate. The cylindrical geometry of the article has an effect of making it difficult to uniformly heat the substrate throughout across the entire thickness or diameter of the substrate. The use of a flatter geometry of aerosol-forming substrate in place of a cylindrical profile may improve the uniformity of heating through the thickness of the substrate. However, the need to pre-heat the aerosol-forming substrate across the entire transverse crosssection to a given vaporisation temperature before application of a first puff to the article remains, with the time required for pre-heating delaying a user from being able to inhale aerosol generated from the substrate.

[0004] It is an aim of the present disclosure to provide an aerosol-generating article which requires less pre-heating in order to reach a desired aerosolisation temperature.

[0005] According to one aspect of the present disclosure, there may be provided an aerosolgenerating article for use with an aerosol-generating device to generate an aerosol, the aerosolgenerating article having a length extending in an x direction, a width extending in a y direction and a height extending in a z direction, the height being less than each of the length and the width. The aerosol-generating article may comprise a cavity extending in a downstream direction between an air inlet and an air outlet. The cavity may comprise successively arranged upstream and downstream portions. The air inlet may form part of the upstream portion and the air outlet form part of the downstream portion. The transverse cross-sectional area of the downstream portion of the cavity may be less than the transverse cross-sectional area of the upstream portion of the cavity, and the volume of the downstream portion of the cavity less than the volume of the upstream portion of the cavity. Aerosol-forming substrate may be arranged in both upstream and downstream portions of the cavity.

[0006] For the purpose of the present disclosure, the “height” of the aerosol-generating article may also be referred to as the “thickness” of the aerosol-generating article. The smaller transverse cross-sectional area and volume of the downstream portion of the cavity relative to the upstream portion of the cavity provides a smaller space for containment of aerosol-forming substrate. The aerosol-forming substrate in the smaller space of the downstream portion will require less energy and time for pre-heating to a vaporisation temperature of the substrate compared to heating a larger amount of aerosol-forming substrate in the larger upstream portion of the cavity. The presence of the air outlet in the downstream portion of the cavity also means that vapours more rapidly generated by pre-heating of the aerosol-forming substrate in the downstream portion can quickly be conveyed to the air outlet for subsequent inhalation by a user. So, the smaller downstream portion and its proximity to the air outlet allows a user to take a first puff after a shorter duration of pre-heating of the aerosol-forming substrate.

[0007] The aerosol-forming substrate in the downstream portion of the cavity may be associated with the generation of aerosol for a first puff of a series of puffs, whereas the aerosol-forming substrate in the upstream portion of the cavity may be associated with subsequent puffs of the series of puffs. So, preferably the mass of aerosol-forming substrate in the downstream portion of the cavity will be less than the mass of aerosol-forming substrate in the upstream portion of the cavity.

[0008] The transverse cross-sectional area of the air inlet may be smaller than the transverse cross-sectional area of an upstream end of the cavity. Similarly, the transverse cross-sectional area of the air outlet may be smaller than the transverse cross-sectional area of a downstream end of the cavity.

[0009] Preferably, the downstream portion of the cavity may be substantially filled with aerosolforming substrate. This enhances the quantity of volatile compounds evolved from the aerosolforming substrate during pre-heating for use in a first puff of a series of puffs. Each of the upstream and downstream portions of the cavity may be substantially filled with aerosol-forming substrate.

[0010] One or both of the packing density and the bulk density of the aerosol-forming substrate in the downstream portion of the cavity may be greater than for the aerosol-forming substrate in the upstream portion of the cavity. A higher value of packing density and / or bulk density in the downstream portion may enhance the quantity of volatile compounds evolved from the aerosolforming substrate during pre-heating for use in the first puff of a series of puffs.

[0011] The packing density of aerosol-forming substrate in the downstream portion of the cavity may be between 0.5 and 0.9, for example between 0.6 and 0.9, for example between 0.6 and 0.8.

[0012] The mass of aerosol-forming substrate within the cavity may be dependent on various factors, including the proportion of the cavity intended to be filled with aerosol-forming substrate, the density of the aerosol-forming substrate, the level of compaction of the aerosol-forming substrate and the size of the cavity. By way of example, the total mass of the aerosol-forming substrate in the cavity of the aerosol-generating article may be between 50 mg and 350 mg, or between 100 mg and 300 mg, or between 125 mg and 250 mg, or between 150 mg and 200 mg. The aerosol-forming substrate employed in the cavity may be in the form of any one or more of shredded aerosol-forming substrate, strips of aerosol-forming substrate, strands of aerosolforming substrate, particles of aerosol-forming substrate, one or more sheets of aerosol-forming substrate, one or more gathered sheets of aerosol-forming substrate, cut filler dispersed within a solid binder matrix, a plurality of beads or granules of aerosol-forming substrate.

[0013] The aerosol-forming substrate may preferably comprise tobacco, for example, tobacco particles, tobacco cut filler or cast leaf tobacco. The aerosol-forming substrate may comprise homogenised tobacco.

[0014] Preferably, the aerosol-forming substrate may be a free-flowing aerosol-forming substrate. A free-flowing aerosol-forming substrate may be better able to efficiently conform to the size and shape of the cavity, thereby providing for efficient packing of the substrate within the cavity. The free-flowing aerosol-forming substrate may be arranged to substantially fill the entirety of at least the downstream portion of the cavity. In this manner, the quantity of volatile compounds evolved from the aerosol-forming substrate during pre-heating for use in a first puff of a series of puffs may be enhanced. In other examples, the free-flowing aerosol-forming substrate may be arranged to substantially fill the entirety of both the upstream and downstream portions of the cavity. The free-flowing aerosol-forming substrate may comprise or consist of a plurality of beads or granules.

[0015] Where the aerosol-forming substrate is in the form of a plurality of beads or granules, the beads or granules can readily adapt to the specific shape of the cavity. The provision of an aerosol-forming substrate in the form of a plurality of beads or granules also advantageously provides a substrate with a high surface to volume ratio, which optimises release of aerosol from the substrate upon heating.

[0016] Where the aerosol-forming substrate is in the form of a plurality of beads or granules, the bulk density of the plurality of beads or granules is preferably at least 200 mg per cubic centimetre, more preferably at least 210 mg per cubic centimetre, more preferably at least 225 mg per cubic centimetre, more preferably at least 240 mg per cubic centimetre more preferably at least 250 mg per cubic centimetre. Preferably, the bulk density of the plurality of beads or granules is less than or equal to 500 mg per cubic centimetre, more preferably less than or equal to 485 mg per cubic centimetre, more preferably less than or equal to 475 mg per cubic centimetre, more preferably less than or equal to 465 mg per cubic centimetre, more preferably less than or equal to 450 mg per cubic centimetre. For example, the bulk density of the plurality of beads or granules may be between 200 mg per cubic centimetre and 500 mg per cubic centimetre, or between 210 mg per cubic centimetre and 485 mg per cubic centimetre, or between 225 mg per cubic centimetre and 475 mg per cubic centimetre, or between 240 mg per cubic centimetre and 465 mg per cubic centimetre, or between 250 mg per cubic centimetre and 450 mg per cubic centimetre. The bulk density of the plurality of beads or granules is defined as the total weight of the plurality of beads or granules, divided by the volume of the space occupied by the plurality of beads or granules. The aerosol-forming substrate may comprise an aerosol-former, for example an aerosol former selected from the list consisting of glycerine and propylene glycol, for example in which the aerosol-forming substrate has an aerosol-former content of greater than 20 wt % on a dry weight basis, for example greater than 25 wt %, or greater than 30 wt %, for example greater than 35 wt %. The use of an aerosol former may facilitate the promote the generation of aerosol from the aerosol-forming substrate through heating rather than burning of the substrate.

[0017] The aerosol-forming substrate may comprise one or more flavour compounds.

[0018] The downstream portion may have a uniform transverse cross-sectional area over at least 75%, for example at least 85%, for example at least 95%, for example all of a separation distance between an upstream end of the downstream portion and a downstream end of the downstream portion. By way of example, the downstream portion of the cavity may be substantially rectangular when viewed in plan, for example when viewed along the z direction. However, one or more curved transitions may be provided at the upstream end of the downstream portion of the cavity (for example, at a junction between the upstream and downstream portions of the cavity) and / or at the downstream end of the downstream portion of the cavity (for example, at a junction between laterally opposed sidewalls of the downstream portion of the cavity and an downstream end wall of the cavity).

[0019] Alternatively, the downstream portion of the cavity may converge in transverse cross- sectional area on progression in the downstream direction towards the air outlet. The progressive convergence in transverse cross-sectional area may be monotonic between upstream and downstream ends of the downstream portion of the cavity. A progressive reduction in transverse cross-sectional area with closer proximity to the air outlet is consistent with facilitating rapid heating and vaporisation of volatile compounds of the aerosol-forming substrate located immediately adjacent to the air outlet to form an aerosol for a first puff of a series of puffs.

[0020] The downstream portion of the cavity may define between 5% and 35%, for example between 5% and 30%, for example between 5% and 20%, for example between 5% and 15%, for example between 5% and 10% of a separation distance between an upstream end of the cavity and a downstream end of the cavity. This separation distance may define a length of the cavity. Having the downstream portion of the cavity defining a minority of the separation distance between upstream and downstream ends of the cavity is consistent with aerosol-forming substrate in the downstream portion of the cavity serving as a source of volatile compounds for a first puff of a series of puffs, with the substrate in the larger upstream portion of the cavity serving as a source of volatile compounds for subsequent puffs of the series of puffs.

[0021] The upstream portion of the cavity may be substantially uniform in transverse cross-section over at least 75%, for example at least 85%, for example at least 95%, for example all of a separation distance between an upstream end of the upstream portion to a downstream end of the upstream portion. By way of example, the upstream portion of the cavity may be substantially rectangular when viewed in plan, for example when viewed along the z direction. However, one or more curved transitions may be provided at the upstream end of the upstream portion of the cavity (for example, at a junction between an upstream end wall of the cavity and laterally opposed sidewalls of the upstream portion of the cavity) and / or at a downstream end of the upstream portion of the cavity (for example, at a junction between the upstream and downstream portions of the cavity).

[0022] The cavity may have a uniform height between an upstream end of the cavity and a downstream end of the cavity. The provision of a uniform height for the cavity may provide greater uniformity in heating through the thickness (or height) of the aerosol-forming substrate, thereby improving the quality of the resulting aerosol and the user experience during use of the article in a usage session.

[0023] The cavity may preferably be symmetrically arranged across first and second halves of the width of the aerosol-generating article. Additionally or alternatively, the cavity may be symmetrically arranged across first and second halves of the height of the aerosol-generating article.

[0024] The aerosol-generating article may further comprise upper and lower external surfaces separated from each other in the z direction. The separation between the upper and lower external surfaces may define the height of the aerosol-generating article.

[0025] The upper and lower external surfaces may be planar. The upper and lower external surfaces may be parallel to each other.

[0026] The upper and lower external surfaces may each be outwardly-convex.

[0027] The cavity may be at least partially defined by a frame extending between the upper and lower external surfaces.

[0028] The air inlet and air outlet may be defined in the frame.

[0029] The frame may comprise a plurality of layers successively laid over each other in the z direction. The air inlet and air outlet may be defined by respective cut-outs in at least one of the plurality of layers of the frame.

[0030] The frame may comprise a cellulosic material. The cellulosic material may have a grammage between 300 grams per square metre and 900 grams per square metre. The cellulosic material may be paper, paperboard, or cardboard.

[0031] The width of the cavity may be defined by laterally opposed sidewalls of the frame.

[0032] The length of the cavity may extend in the x direction. The width of the cavity may extend in the y direction.

[0033] The cavity may extend in the z direction through the full height of the frame to define opposed upper and lower openings through corresponding upper and lower surfaces of the frame, upper and lower sheets coupled to the respective upper and lower surfaces of the frame to cover the opposed upper and lower openings. The upper and lower sheets may define the respective upper and lower external surfaces.

[0034] The upper and lower sheets may be substantially impermeable, for example being water impermeable.

[0035] The upper and lower sheets may have a permeability of between 1 and 5 Coresta units.

[0036] The upper and lower sheets may each comprise or consist of a metallic layer, for example a metallic foil. The upper and lower sheets may each be formed of a laminate of paper and metallic foil layers. The use of a thermally conductive material for the upper and lower sheets allows the sheets to efficiently be heated and, in turn, convey heat to the aerosol-forming substrate contained within the cavity of the article.

[0037] According to another aspect of the present disclosure, there may be provided an aerosolgenerating system. The aerosol-generating system may comprise an aerosol-generating article according to any of aspects described above, and an aerosol-generating device. The aerosolgenerating device may comprise an electrically-powered heating arrangement and a chamber for receiving the aerosol-generating article. On the aerosol-generating article being operably positioned in the chamber, the heating arrangement and aerosol-generating article may be aligned relative to each other such that the heating arrangement is positioned to overlie a greater percentage proportion of the downstream portion of the cavity than the upstream portion of the cavity.

[0038] Preferably, the heating arrangement may extend over at least 90%, for example at least 95%, for example substantially all of the downstream portion of the cavity.

[0039] The heating arrangement may extend over a length and a width to be substantially rectangular in plan. The length of the heating arrangement may be aligned along the length of the cavity. Laterally opposed outermost regions of the upstream portion of the cavity may be free of coverage by the heating arrangement.

[0040] Conveniently, an upstream end of the heating arrangement may be aligned with an upstream end of the cavity and a downstream end of the heating arrangement aligned with a downstream end of the cavity.

[0041] The heating arrangement may comprise a plurality of tracks aligned parallel to each other.

[0042] The heating arrangement may comprise or consist of a resistive heating element.

[0043] As used herein, the term “aerosol-generating article” may refer to an article able to generate, or release, an aerosol.

[0044] As used herein, the term “aerosol-forming substrate” may refer to a substrate capable of releasing an aerosol or volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. An aerosol-forming substrate may comprise an aerosol-forming material. An aerosol-forming substrate may be adsorbed, coated, impregnated, or otherwise loaded onto a carrier or support. An aerosol-forming substrate may conveniently be part of an aerosol-generating article or smoking article. As used herein, the term “granule” refers to a discrete, solid particle formed of the aerosolforming substrate as defined above. The granule may have a regular or irregular shape.

[0045] As used herein, the term “bead” refers to a discrete, solid particle formed of the aerosolforming substrate as defined above and which has a rounded, typically spherical, form.

[0046] As used herein, the term “aerosol-generating device” may refer to a device for use with an aerosol-generating article to enable the generation, or release, of an aerosol.

[0047] As used herein, the term “aerosol former” may refer to any suitable known compound or mixture of compounds that, in use, facilitates formation of an aerosol. The aerosol may be a dense and stable aerosol. The aerosol may be substantially resistant to thermal degradation at the operating temperature of the aerosol-forming substrate or aerosol-generating article.

[0048] As used herein with reference to the invention, the term “nicotine”, is used to describe nicotine, nicotine base or a nicotine salt.

[0049] As used herein with reference to the invention, the terms “proximal”, “distal”, “upstream” and “downstream” are used to describe the relative positions of components, or portions of components, of the aerosol-generating article.

[0050] As used herein, the term “homogenised tobacco material” encompasses any tobacco material formed by the agglomeration of particles of tobacco material. Sheets or webs of homogenised tobacco material are formed by agglomerating particulate tobacco obtained by grinding or otherwise powdering of one or both of tobacco leaf lamina and tobacco leaf stems. In addition, homogenised tobacco material may comprise a minor quantity of one or more of tobacco dust, tobacco fines, and other particulate tobacco by-products formed during the treating, handling and shipping of tobacco. The sheets of homogenised tobacco material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art.

[0051] The term “cast leaf” is used herein to refer to a product made by a casting process that is based on casting a slurry comprising plant particles (for example, clove particles or tobacco particles and clove particles in a mixture) and a binder (for example, guar gum) onto a supportive surface, such as a belt conveyor, drying the slurry and removing the dried sheet from the supportive surface. An example of the casting or cast leaf process is described in, for example, US-A-5,724,998 for making cast leaf tobacco. In a cast leaf process, particulate plant materials are produced by pulverizing, grinding, or comminuting parts of the plant. The particles produced from one or more plants are mixed with a liquid component, typically water, to form a slurry. Other components in the slurry may include fibres, a binder and an aerosol former. The particulate plant materials may be agglomerated in the presence of the binder. The slurry is cast onto a supportive surface and dried into a sheet of homogenized plant material. Preferably, homogenized plant material used in articles according to the present invention may be produced by casting. Such homogenized plant material may comprise agglomerated particulate plant material. As used herein, resistance to draw is expressed with the units of pressure “mm H2O” or “mm WG” or “mm of water gauge” and may be measured in accordance with ISO 6565:2002.

[0052] The invention is defined in the claims. However, below there 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 another example, embodiment, or aspect described herein.

[0053] Example Ex1 : An aerosol-generating article for use with an aerosol-generating device to generate an aerosol, the aerosol-generating article having a length extending in an x direction, a width extending in a y direction and a height extending in a z direction, the height being less than each of the length and the width, the aerosol-generating article comprising: a cavity extending in a downstream direction between an air inlet and an air outlet, the cavity comprising successively arranged upstream and downstream portions, the air inlet forming part of the upstream portion and the air outlet forming part of the downstream portion, the transverse cross-sectional area of the downstream portion of the cavity being less than the transverse cross- sectional area of the upstream portion of the cavity, the volume of the downstream portion of the cavity being less than the volume of the upstream portion of the cavity, wherein aerosol-forming substrate is arranged in both upstream and downstream portions of the cavity.

[0054] Example Ex1 a: An aerosol-generating article according to Ex1 , wherein the transverse cross-sectional area of the air inlet is smaller than the transverse cross-sectional area of an upstream end of the cavity.

[0055] Example Ex1 b: An aerosol-generating article according to either one of Ex1 or Ex1 a, wherein the transverse cross-sectional area of the air outlet is smaller than the transverse cross- sectional area of a downstream end of the cavity.

[0056] Example Ex2: An aerosol-generating article according to any one of Ex1 to Ex1 b, wherein the downstream portion of the cavity is substantially filled with aerosol-forming substrate.

[0057] Example Ex3: An aerosol-generating article according to Ex2, wherein each of the upstream and downstream portions of the cavity are substantially filled with aerosol-forming substrate.

[0058] Example Ex4: An aerosol-generating article according to any one of Ex1 to Ex3, wherein one or both of the packing density and the bulk density of the aerosol-forming substrate in the downstream portion of the cavity may be greater than for the aerosol-forming substrate in the upstream portion of the cavity.

[0059] Example Ex5: An aerosol-generating article according to any one of Ex1 to Ex4, wherein the packing density of aerosol-forming substrate in the downstream portion of the cavity is between 0.5 and 0.9, for example between 0.6 and 0.9, for example between 0.6 and 0.8.

[0060] Example Ex6: An aerosol-generating article according to any one of Ex1 to Ex5, wherein the aerosol-forming substrate is a free-flowing aerosol-forming substrate. Example Ex7: An aerosol-generating article according to Ex6, wherein the free-flowing aerosol-forming substrate is arranged to substantially fill at least the downstream portion of the cavity.

[0061] Example Ex8: An aerosol-generating article according to Ex7, wherein the free-flowing aerosol-forming substrate is arranged to substantially fill both the upstream and downstream portions of the cavity.

[0062] Example Ex9: An aerosol-generating article according to any one of Ex6 to Ex8, wherein the free-flowing aerosol-forming substrate comprises or consists of a plurality of beads or granules.

[0063] Example Ex10: An aerosol-generating article according to any one of Ex1 to Ex9, wherein the downstream portion has a uniform transverse cross-sectional area over at least 75%, for example at least 85%, for example at least 95%, for example all of a separation distance between an upstream end of the downstream portion and a downstream end of the downstream portion.

[0064] Example Ex1 1 : An aerosol-generating article according to any one of Ex1 to Ex9, wherein the downstream portion of the cavity converges in transverse cross-sectional area on progression in the downstream direction towards the air outlet.

[0065] Example Ex12: An aerosol-generating article according to any one of Ex1 to Ex1 1 , wherein the downstream portion defines between 5% and 35%, for example between 5% and 30%, for example between 5% and 20%, for example between 5% and 15%, for example between 5% and 10% of a separation distance between an upstream end of the cavity and a downstream end of the cavity.

[0066] Example Ex13: An aerosol-generating article according to any one of Ex1 to Ex12, wherein the upstream portion of the cavity is substantially uniform in transverse cross-section over at least 75%, for example at least 85%, for example at least 95%, for example all of a separation distance between an upstream end of the upstream portion to a downstream end of the upstream portion.

[0067] Example Ex14: An aerosol-generating article according to any one of Ex1 to Ex13, wherein the cavity has a uniform height between an upstream end of the cavity and a downstream end of the cavity.

[0068] Example Ex15: An aerosol-generating article according to any one of Ex1 to Ex14 wherein the cavity is symmetrically arranged across first and second halves of the width of the aerosolgenerating article.

[0069] Example Ex16: An aerosol-generating article according to any one of Ex1 to Ex15, wherein the cavity is symmetrically arranged across first and second halves of the height of the aerosolgenerating article.

[0070] Example Ex17: An aerosol-generating article according to any one of Ex1 to Ex16, further comprising upper and lower external surfaces separated from each other in the z direction. Example Ex18: An aerosol-generating article according to Ex17, wherein the upper and lower external surfaces are planar.

[0071] Example Ex19: An aerosol-generating article according to Ex18, wherein the upper and lower external surfaces are parallel to each other.

[0072] Example Ex20: An aerosol-generating article according to Ex17, wherein the upper and lower external surfaces are each outwardly-convex.

[0073] Example Ex21 : An aerosol-generating article according to any one of Ex17 to Ex20, wherein the cavity is at least partially defined by a frame extending between the upper and lower external surfaces.

[0074] Example Ex22: An aerosol-generating article according to Ex21 , wherein the air inlet and air outlet are defined in the frame.

[0075] Example Ex23: An aerosol-generating article according to either one of Ex21 or Ex22, wherein the frame comprises a plurality of layers successively laid over each other in the z direction.

[0076] Example Ex24: An aerosol-generating article according to Ex23, wherein the air inlet and air outlet are defined by respective cut-outs in at least one of the plurality of layers of the frame.

[0077] Example Ex25: An aerosol-generating article according to any one of Ex21 to Ex24, wherein a width of the cavity is defined by laterally opposed sidewalls of the frame.

[0078] Example Ex26: An aerosol-generating article according to any one of Ex21 to Ex25, wherein the cavity extends in the z direction through the full height of the frame to define opposed upper and lower openings through corresponding upper and lower surfaces of the frame, upper and lower sheets coupled to the respective upper and lower surfaces of the frame to cover the opposed upper and lower openings.

[0079] Example Ex27: An aerosol-generating article according to Ex26, wherein the upper and lower sheets define the respective upper and lower external surfaces.

[0080] Example Ex28: An aerosol-generating article according to either one of Ex26 or Ex27, wherein the upper and lower sheets are substantially impermeable, for example being water impermeable.

[0081] Example Ex29: An aerosol-generating article according to Ex28, wherein the upper and lower sheets have a permeability of between 1 and 5 Coresta units.

[0082] Example Ex30: An aerosol-generating article according to any one of Ex26 to Ex29, wherein the upper and lower sheets each comprise or consist of a metallic layer, for example a metallic foil.

[0083] Example Ex31 : An aerosol-generating system comprising: an aerosol-generating article according to any one of Ex1 to Ex30; and an aerosol-generating device comprising an electrically-powered heating arrangement and a chamber for receiving the aerosol-generating article; wherein on the aerosol-generating article being operably positioned in the chamber, the heating arrangement and aerosol-generating article are aligned relative to each other such that the heating arrangement is positioned to overlie a greater percentage proportion of the downstream portion of the cavity than the upstream portion of the cavity.

[0084] Example Ex32: An aerosol-generating system according to Ex31 , wherein the heating arrangement extends over at least 90%, for example at least 95%, for example substantially all of the downstream portion of the cavity.

[0085] Example Ex33: An aerosol-generating system according to either one of Ex31 or Ex32, wherein the heating arrangement extends over a length and a width to be substantially rectangular in plan, the length of the heating arrangement aligned along the length of the cavity, laterally opposed outermost regions of the upstream portion of the cavity being free of coverage by the heating arrangement.

[0086] Example Ex33a: An aerosol-generating system according to any one of Ex31 to Ex33, wherein an upstream end of the heating arrangement is aligned with an upstream end of the cavity and a downstream end of the heating arrangement is aligned with a downstream end of the cavity.

[0087] Example Ex34: An aerosol-generating system according to any one of Ex31 to Ex33a, wherein the heating arrangement comprises a plurality of tracks aligned parallel to each other.

[0088] Example Ex35: An aerosol-generating system according to any one of Ex31 to Ex34, wherein the heating arrangement comprises or consists of a resistive heating element.

[0089] Examples will now be further described with reference to the figures in which:

[0090] Figure 1 is a plan view of a frame of an aerosol-generating article according to a first embodiment of the present disclosure;

[0091] Figure 2 is a perspective view of the frame of figure 1 ;

[0092] Figure 3 is a perspective exploded view of the components of the aerosol-generating article according to the first embodiment of the present disclosure, including the frame of figures 1 and 2;

[0093] Figure 4 is a perspective view of the aerosol-generating article of figure 3 in an assembled state;

[0094] Figure 5 is a partial cut-away plan view of the aerosol-generating article of figure 4 during use, showing the relative positioning of a heating element of an aerosol-generating device and a cavity of the aerosol-generating article;

[0095] Figure 6 is a plan view of a frame of an aerosol-generating article according to a second embodiment of the present disclosure;

[0096] Figure 7 is a perspective view of the frame of figure 6;

[0097] Figure 8 is a perspective exploded view of the components of the aerosol-generating article according to the second embodiment of the present disclosure, including the frame of figures 6 and 7; Figure 9 is a perspective view of the aerosol-generating article of figure 8 in an assembled state;

[0098] Figure 10 is a partial cut-away plan view of the aerosol-generating article of figure 9 during use, showing the relative positioning of a heating element of an aerosol-generating device and a cavity of the aerosol-generating article;

[0099] Figure 11 is a perspective exploded view of a multi-layered frame for use as part of the aerosol-generating article of figures 1 to 5;

[0100] Figure 12 shows a schematic view of an aerosol-generating device according to an embodiment of the present disclosure, the device configured to engage with an aerosolgenerating article, for example the aerosol-generating articles of any of figures 1 to 10;

[0101] Figure 13 shows a schematic end view of the aerosol-generating device of figure 12;

[0102] Figure 14 is a schematic view showing an aerosol-generating article (for example, the aerosol-generating article of any of figures 1 to 10) in engagement with the aerosol-generating device of figure 12;

[0103] Figure 15 is a schematic view of an alternative embodiment to that of figures 12 to 14, showing an aerosol-generating article in engagement with an aerosol-generating device.

[0104] Figure 1 is a plan view of a frame 101 of an aerosol-generating article 100 according to a first embodiment of the present disclosure. Figure 2 is a perspective view of the frame 101 of figure 1 . The frame 101 is shown alongside the x, y and z axes of a cartesian coordinate system. The frame 101 defines a cavity 102. The cavity 102 is located in one half of a length of the frame 101 and extends through the full height of the frame 101 along the z direction between lower and upper surfaces 103, 104 of the frame. The cavity 102 extends in the x direction between an upstream end 105 and a downstream end 106. The separation between the upstream end 105 and downstream end 106 of the cavity 102 defines a length of the cavity. The separation between laterally opposed sidewalls 107, 108 of the frame 101 defines a width of the cavity 102. An air inlet 109 is located at the upstream end 105 of the cavity 102. The air inlet 109 is defined by a cut-out or channel extending in the x direction through an upstream end wall of the frame 101 . An air outlet 110 is located at the downstream end 106 of the cavity 102. The air outlet 1 10 is defined by a cut-out or channel extending through the frame 101 in the x direction. The air outlet 110 extends from the downstream end 106 of the cavity 102, through the frame 101 to emerge through a downstream end wall of the frame 101. The air inlet 109 may be referred to as an air inlet channel and the air outlet 1 10 may be referred to as an air outlet channel. As can be seen in the figures, the transverse cross-sectional area of the air inlet 109 is smaller in size than the transverse cross-sectional area of the upstream end 105 of the cavity 102. Similarly, the transverse cross-sectional area of the air outlet 1 10 is smaller in size than the transverse cross- sectional area of the downstream end 106 of the cavity 102. The cavity 102 has an upstream portion 11 1 and a downstream portion 1 12. The upstream and downstream portions 1 11 , 1 12 are both generally rectangular when viewed in plan along the z direction. However, the laterally opposed sidewalls 107, 108 each include a curved transition 113 between the upstream and downstream portions 111 , 1 12. A curved transition 1 14 is also present between the laterally opposed sidewalls 107, 108 and the upstream end 105 of the cavity 102. Arrows show the intended direction of air-flow into the cavity 102 via air inlet 109 and out from the cavity 102 via air outlet 1 10. The cavity 102 is intended to contain aerosol-forming substrate 120 (not shown in figures 1 and 2). The downstream portion 112 of the cavity 102 extends (in the x direction) for about 25% of the length of the cavity. The width (measured in the y direction) of the downstream portion 1 12 of the cavity 102 is about 60% of the width of the upstream portion 11 1. So, the volume of the downstream portion 112 of the cavity 102 is considerably less than that of the upstream portion 11 1 of the cavity. Although the cavity 102 is asymmetrical long the length of the frame 101 (along the x direction), the cavity is symmetrical across opposite halves of the width of the frame 101 (along the y direction) and opposite halves of the height of the frame 101 (along the z direction).

[0105] Figure 3 is a perspective exploded view of the components of the aerosol-generating article 100, including the frame 101 of figures 1 and 2. Figure 3 shows the entirety of the cavity 102 filled with about 180 mg of aerosol-forming substrate 120. As will be appreciated from figure 3 when seen in conjunction with figures 1 and 2, the volume of aerosol-forming substrate 120 contained in the downstream portion 1 12 of the cavity 102 is less than the volume of aerosolforming substrate 120 contained in the upstream portion 11 1 of the cavity. The aerosol-generating article 100 also includes lower and upper sheets 131 , 132 for fixing to corresponding lower and upper surfaces 103, 104 of the frame 101. It will be appreciated that the mass of aerosol-forming substrate 120 used within the cavity 102 may vary depending on the proportion of the cavity intended to be filled with aerosol-forming substrate, the density of the aerosol-forming substrate, the level of compaction of the aerosol-forming substrate and the size of the cavity 102.

[0106] For the illustrated embodiment, the aerosol-forming substrate 120 is in the form of a plurality of spherical beads of aerosol-generating material. The beads form a free-flowing substrate. The filling of the cavity 102 with the beads reduces scope for movement or redistribution of the beads throughout the cavity. The spherical beads of aerosol-forming substrate 120 have a mean diameter of 1 .5 millimetres and a density of 1 .3 grams per cubic centimetre. The beads are formed of an aerosol-generating material comprising plant particles, aerosol former and a hydrocolloid binder. Some examples of suitable compositions for the aerosol-generating material forming the beads are provided below. Example

[0107] Suitable compositions for forming beads or granules of aerosol-generating material are set out in Table 1 below:

[0108] Table 1

[0109] All amounts are shown as percentages by weight, on a dry weight basis, based on the total weight of the aerosol-generating material.

[0110] It will be appreciated that in other embodiments, other forms of aerosol-forming substrate may be used in place of a plurality of beads, such as cut filler, or shreds, strips or sheets of homogenised tobacco.

[0111] The frame 101 is formed of cardboard. The frame 101 has a length (extending in the x direction) of about 30 mm, a width (extending in the y direction) of about 12 mm and a height (extending in the z direction) of about 3 mm. The cavity 102 has a length (extending in the x direction) of about 14 mm, with the upstream portion 11 1 being about 10.5 mm long and the downstream portion 1 12 being about 3.5 mm long. So, the length of the cavity 102 is divided in a ratio of about 75% : 25% between the upstream and downstream portions 1 11 , 112. The cavity 102 has a maximum width (extending in the y direction) of about 7 mm, with this width being the width of the upstream portion 1 11. The downstream portion 112 has a width of about 4.2 mm (corresponding to around 60% of the width of the wider upstream portion 1 11 ).

[0112] The lower and upper sheets 131 , 132 are formed of a lamination of a layer of paper and a layer of metallic foil. The metallic foil may be aluminium or a similar thermally conductive metallic material. The lower and upper sheets 131 , 132 are essentially impermeable to water. The lower and upper sheets 131 , 132 each have a thickness of about 45 micrometres. The length and width of the lower and upper sheets 131 , 132 correspond to that of the frame 101.

[0113] The aerosol-generating article 100 has a length (extending in the x direction) of about 30 mm, a width (extending in the y direction) of about 12 mm and a height (extending in the z direction) of about 3.1 mm.

[0114] During assembly of the components of the aerosol-generating article 100, the lower sheet 131 is bonded to the lower surface 103 of the frame 101. The cavity 102 is then filled with the beads of aerosol-forming substrate 120 until the beads are approximately level with the upper surface 104 of the frame 101 . The upper sheet 132 is then bonded to the upper surface 104 of the frame 101 to cover and close the cavity 102 (see figure 4).

[0115] Figure 4 is a perspective view of the aerosol-generating article 100 of figure 3 after assembly of the components of the article. In a usage session, heat would be applied to heat the aerosolforming substrate 120 in the cavity 102 to a vaporisation temperature, the vaporisation temperature being sufficient to vaporise one or more desired volatile compounds from the aerosolforming substrate.

[0116] Figure 5 shows a partial cut-away plan view of the aerosol-generating article 100 of figure 4 with a heating element 1040 of an aerosol-generating device 1000 disposed over the cavity 102; figure 5 does not show the upper sheet 132 to enable the relative positioning of the heating element 1040 and the aerosol-forming substrate 120 in the cavity 102 to be clearly seen. The heating element 1040 is generally rectangular in plan and aligned along the length of the cavity 102. As can be seen from figure 5, the heating element 1040 is positioned to not overlie either of the air inlet channel 109 or the air outlet channel 1 10. The heating element 1040 is aligned with the upstream end 105 and the downstream end 106 of the cavity 102. The width of the downstream portion 1 12 of the cavity 102 and the relative positions of the heating element 1040 and the cavity is such that all of the area of the downstream portion 112 of the cavity 102 (when viewed in plan along the z direction) is overlaid by the heating element. Opposed lateral outward portions 1 15, 116 of the upstream portion 1 11 of the cavity 102 are not covered by the heating element 1040 and are therefore subject to a reduced level of heating. The heating element 1040 acts to heat the beads of aerosol-forming substrate 120 within the cavity 102, with the heating effect being strongest for that part of the aerosol-forming substrate 120 overlaid by the heating element 1040. For the aerosol-forming substrate 120 in the upstream portion 1 11 of the cavity 102, heat imparted to the aerosol-forming substrate overlaid by the heating element 1040 would tend to be conducted into the cooler aerosol-forming substrate located in the opposed lateral outward portions 1 15, 116 of the upstream portion 11 1 of the cavity 102. However, as the entirety of the downstream portion 112 of the cavity 102 is overlaid by the heating element 1040, the aerosol-forming substrate 120 in the downstream portion 112 of the cavity 102 suffers less loss of heat. Further, as the volume and mass of aerosol-forming substrate 120 in the downstream portion 1 12 is smaller than in the upstream portion 11 1 , less heat is required to increase the temperature of the aerosol-forming substrate in the downstream portion to a temperature sufficient to attain the vaporisation temperature. The period of time taken for the aerosol-forming substrate 120 to achieve the vaporisation temperature from activation of the heating element 1040 is referred to as the pre-heating time. So, the aerosol-forming substrate 120 in the downstream portion 112 of the cavity 102 will attain the vaporisation temperature before the substrate in the upstream portion 11 1 of the cavity. The location of the aerosol-forming substrate 120 of the downstream portion 112 of the cavity 102 adjacent to the air outlet 1 10 allows for vapours evolved from the rapidly heated aerosol-forming substrate in the downstream portion of the cavity to be carried downstream through the air outlet 110 entrained in an airflow for a first puff applied to article 100 in the usage session. An airflow into and through the cavity 102 may be induced by a user drawing on a proximal or mouth end 117 of the article 100, with the resulting suction causing an inflow of air into the cavity 102 via the air inlet 109, through between the beads of aerosolforming substrate 120 and out through the air outlet 110. Vapours evolved from heating of the aerosol-forming substrate 120 become entrained in the airflow. The entrained airflow cools and condenses to form an aerosol on travelling downstream through the air outlet 1 10 towards the proximal or mouth end 117 for inhalation by a user. Continued heating by the heating element 1040 will act to bring the aerosol-forming substrate 120 in the upstream portion 11 1 of the cavity 102 to the vaporisation temperature, for use in subsequent puffs of the usage session.

[0117] Figure 6 is a plan view of a frame 201 of an aerosol-generating article 200 according to a second embodiment of the present disclosure. Figure 7 is a perspective view of the frame 201 of figure 6. Features in common with the first embodiment of figures 1 to 5 are referred to with like reference signs, but commencing with a ‘2’ instead of a ‘1 ’. The frame 201 differs from frame 101 in that the downstream portion 212 of the cavity 202 progressively reduces in transverse crosssection on moving closer towards the air outlet 210. Figures 6 and 7 show the downstream portion 212 of the cavity 202 being generally trapezoidal in plan. So, the width of the downstream portion 212 of the cavity 202 reduces on progressing in the downstream direction (along the x direction) towards the air outlet 210. Arrows show the intended direction of air-flow into the cavity 202 via the air inlet 209 and out from the cavity 202 via the air outlet 210. The cavity 202 is intended to be occupied with aerosol-forming substrate 220 (not shown in figures 6 and 7) in the same manner described for the cavity 102 of the first embodiment. The volume of the downstream portion 212 of the cavity 202 is considerably less than that of the upstream portion 21 1 of the cavity.

[0118] Figure 8 is a perspective exploded view of the components of the aerosol-generating article 200, including the frame 201 of figures 6 and 7. Figure 8 shows the entirety of the cavity 202 filled with aerosol-forming substrate 220. The aerosol-forming substrate 220 is in the form of a plurality of beads of aerosol-generating material, in common with the aerosol-forming substrate 120 of the first embodiment.

[0119] The components of the aerosol-generating article 200 are assembled in the same manner as described for the components of aerosol-generating article 100.

[0120] Figure 9 is a perspective view of the aerosol-generating article 200 of figure 8 after assembly of the components of the article.

[0121] Figure 10 shows a partial cut-away plan view of the aerosol-generating article 200 of figure 9 with a heating element 2040 of an aerosol-generating device 2000 disposed over the cavity 202; figure 10 does not show the upper sheet 232 to enable the relative positioning of the heating element 2040 and the aerosol-forming substrate 220 within the cavity 202 to be clearly seen. The heating element 2040 has the same geometric profile as the heating element 1040 of the first embodiment and is aligned along the length of the cavity 202. As can be seen from figure 10, the heating element 2040 is positioned to not overlie either of the air inlet channel 209 or the air outlet channel 210. The heating element 2040 is aligned with the upstream end 205 and the downstream end 206 of the cavity 202. The width of the downstream portion 212 of the cavity 202 and the relative positions of the heating element 2040 and the cavity is such that nearly all - in excess of 95% - of the area of the downstream portion 212 of the cavity 202 (when viewed in plan along the z direction) is overlaid by the heating element. Small laterally opposed regions 218, 219 of the downstream portion 212 of the cavity 202 are the only parts of the downstream portion not overlaid by the heating element 2040. In common with the first embodiment, opposed lateral outward portions 215, 216 of the upstream portion 21 1 of the cavity 202 are not overlaid by the heating element 2040. The heating element 2040 acts to heat the beads of aerosol-forming substrate 220 within the cavity 202 in the same manner as described for the first embodiment. The aerosolforming substrate 220 in the downstream portion 212 of the cavity 202 will attain the vaporisation temperature before the relatively larger amount of the aerosol-forming substrate in the upstream portion 21 1 of the cavity. The progressive convergence of the transverse cross-sectional area of the downstream portion 212 of the cavity 202 on approaching the air outlet 210 makes the preheating time required to achieve a desired vaporisation temperature for the aerosol-forming substrate 220 less for the substrate at the downstream end of the downstream portion 212 compared to the substrate at the wider, upstream end of the downstream portion. In a similar manner to as described for the first embodiment, the location of the aerosol-forming substrate 220 in the downstream portion 212 of the cavity 202 adjacent to the air outlet 210 allows for vapours evolved from the rapidly heated aerosol-forming substrate in the downstream portion of the cavity to be carried downstream through the air outlet 210 entrained in an airflow for a first puff applied to article 200 in the usage session. As described for the first embodiment, an airflow into and through the cavity 202 may be induced by a user drawing on a proximal or mouth end 217 of the article 200, with the resulting suction causing an inflow of air into the cavity 202 via the air inlet 209, through between the beads of aerosol-forming substrate 220 and out through the air outlet 210. Vapours evolved from heating of the aerosol-forming substrate 220 become entrained in the airflow. The entrained airflow cools and condenses to form an aerosol on travelling downstream through the air outlet 210 towards the proximal or mouth end 217 for inhalation by a user. Continued heating by the heating element 2040 will act to bring the aerosol-forming substrate 220 in the upstream portion 211 of the cavity 202 to the vaporisation, for use in subsequent puffs of the usage session. For the aerosol-generating articles 100, 200, the frame 101 , 201 is illustrated as a homogenous element. However, in other embodiments the frame 101 , 201 may instead be formed of a plurality of layers successively overlaid over each other, for example in the z direction. Figure 1 1 illustrates an exploded view of a frame 301 formed of three layers 3011 , 3012, 3013. The middle layer 3012 of the three layers is provided with two cut-outs. When the three layers 301 1 , 3012, 3013 are bonded to each other to form the frame 301 , the cut-outs in the middle layer define openings for the flow of air into and / or out of the cavity 302 defined by the frame 301. Where the multilayered frame construction of figure 11 is applied to the frame 101 of the aerosolgenerating article 100 of figures 1 to 5, the cut-outs in the middle layer 3012 may define the air inlet channel 109 and the air outlet channel 110.

[0122] Figures 12 and 13 illustrate an aerosol-generating device 4000 configured for use with an aerosol-generating article 400. The aerosol-generating article 400 may be any one of the aerosolgenerating articles 100, 200 previously described or any other aerosol-generating article of the present disclosure.

[0123] The device 4000 is an elongate aerosol-generating device extending between a proximal end 4001 and a distal end 4002. The device 4000 comprises a battery 4010, a controller 4020 and a heater 4030 located within a housing 4040. The controller 4020 controls supply of power from the battery 4010 to the heater 4030. A cavity 4050 is defined in the device 4000, the cavity having an opening 4051 defined in the proximal end 4001 of the device. The opening 4051 is rectangular in shape and is dimensioned to accommodate the transverse cross-section of the aerosol-generating article 400. The cavity 4050 comprises an upper planar surface 4052 and a lower planar surface 4053. The heater 4030 is located in the lower planar surface 4053 to heat a lower surface of the aerosol-generating article 400 inserted into the cavity 4050. An incoming airflow path (not shown) is configured to allow air to flow into the cavity 4050 from outside the device 4000.

[0124] Figure 14 illustrates the device 4000 of figure 12 in engagement with the aerosol-generating article 400. There is little tolerance between outer surfaces of the aerosol-generating article 400 and the internal surfaces of the cavity 4050. Thus, there is a snug fit between the aerosolgenerating article 400 and the device 4000. As the RTD of the aerosol-generating article 400 is negligible, the RTD of the system formed by the combination of aerosol-generating article 400 and aerosol-generating device 4000 is controlled by the air-flow path defined within the device. A user would insert the aerosol-generating article 400 into the cavity 4050 of the aerosol-generating device 4000 such that the heater 4030 is positioned to overlie a cavity 402 of the article, the cavity containing aerosol-forming substrate 420, with an air inlet (not shown) of the article positioned to be in fluid communication with the incoming air flow path of the aerosol-generating device 4000. The user could then activate the aerosol-generating device 4000 to start a usage session, resulting in the heater 4030 commencing pre-heating of the aerosol-forming substrate 420 of the aerosol-generating article 400. The heater 4030 heats a lower surface of the aerosol-generating article 400, resulting in heating of the aerosol-forming substrate 420 in the manner described above for the first and second embodiments of aerosol-generating article. It will be appreciated that the cavity 420 of the article 400 has a geometric profile in accordance with the present disclosure, resulting in the aerosol-forming substrate closest to the air outlet (not shown) of the article first attaining a vaporisation temperature of the substrate during pre-heating. Volatile components of the aerosol-forming substrate 420 are evaporated and condense on flowing through the air outlet of the aerosol-generating article 400 to form an aerosol. The user inhales the aerosol by drawing on the proximal or mouth end of the aerosol-generating article 400. Once the aerosol-forming substrate 420 of the aerosol-generating article 400 has been depleted of volatile components, the aerosol-generating article is removed from the cavity 4050 of the device 4000 and disposed of.

[0125] Although figure 14 shows part of the aerosol-generating article 400 extending outside of the aerosol-generating device 4000, in other embodiments the entirety of an aerosol-generating article may be wholly enclosed within an aerosol-generating device. By way of example, figure 15 illustrates an alternative embodiment to that of figure 14, with like features referred to by the same reference numbers but with the addition of a prime symbol ’. For the alternative embodiment of figure 15, the entirety of aerosol-generating article 400’ is enclosed within the interior of aerosolgenerating device 4000’.

[0126] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances 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 enumerated herein. In this context, therefore, a number “A” is understood as “A” ± 10% of “A”. Within this context, a number “A” may be considered to include numerical values that are within general standard error for the measurement of the property that the number “A” modifies. The number “A”, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which “A” deviates does not materially affect the basic and novel characteristic(s) 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 enumerated herein. The terms “in which” and “wherein” are used synonymously through this specification.

Claims

CLAIMS1 . An aerosol-generating article for use with an aerosol-generating device to generate an aerosol, the aerosol-generating article having a length extending in an x direction, a width extending in a y direction and a height extending in a z direction, the height being less than each of the length and the width, the aerosol-generating article comprising: a cavity extending in a downstream direction between an air inlet and an air outlet, the cavity comprising successively arranged upstream and downstream portions, the air inlet forming part of the upstream portion and the air outlet forming part of the downstream portion, the transverse cross-sectional area of the downstream portion of the cavity being less than the transverse cross-sectional area of the upstream portion of the cavity, the volume of the downstream portion of the cavity being less than the volume of the upstream portion of the cavity, wherein aerosol-forming substrate is arranged in both upstream and downstream portions of the cavity.

2. An aerosol-generating article according to claim 1 , wherein the aerosol-forming substrate is a free-flowing aerosol-forming substrate.

3. An aerosol-generating article according to claim 2, wherein the free-flowing aerosolforming substrate is arranged to substantially fill at least the downstream portion of the cavity.

4. An aerosol-generating article according to either one of claim 2 or claim 3, wherein the free-flowing aerosol-forming substrate comprises or consists of a plurality of beads or granules.

5. An aerosol-generating article according to any one of claims 1 to 4, wherein the downstream portion has a uniform transverse cross-sectional area over at least 75%, for example at least 85%, for example at least 95%, for example all of a separation distance between an upstream end of the downstream portion and a downstream end of the downstream portion.

6. An aerosol-generating article according to any one of claims 1 to 4, wherein the downstream portion of the cavity converges in transverse cross-sectional area on progression in the downstream direction towards the air outlet.

7. An aerosol-generating article according to any one of claims 1 to 6, wherein the downstream portion defines between 5% and 35%, for example between 5% and 30%, for example between 5% and 20%, for example between 5% and 15%, for example between 5% and 10% of a separation distance between an upstream end of the cavity and a downstream end of the cavity.

8. An aerosol-generating article according to any one of claims 1 to 7, wherein the cavity has a uniform height between an upstream end of the cavity and a downstream end of the cavity.

9. An aerosol-generating article according to any one of claims 1 to 8, further comprising upper and lower external surfaces separated from each other in the z direction.

10. An aerosol-generating article according to claim 9, wherein the upper and lower external surfaces are planar.

11. An aerosol-generating article according to claim 9, wherein the upper and lower external surfaces are each outwardly-convex.

12. An aerosol-generating article according to any one of claims 9 to 11 , wherein the cavity is at least partially defined by a frame extending between the upper and lower external surfaces.

13. An aerosol-generating article according to claim 12, wherein the frame comprises a plurality of layers successively laid over each other in the z direction, for example wherein the air inlet and air outlet are defined by respective cut-outs in at least one of the plurality of layers of the frame.

14. An aerosol-generating article according to either one of claim 12 or claim 13, wherein the cavity extends in the z direction through the full height of the frame to define opposed upper and lower openings through corresponding upper and lower surfaces of the frame, upper and lower sheets coupled to the respective upper and lower surfaces of the frame to cover the opposed upper and lower openings, for example wherein the upper and lower sheets each comprise or consist of a metallic layer, for example a metallic foil.

15. An aerosol-generating system comprising: an aerosol-generating article according to any one of claims 1 to 14; and an aerosol-generating device comprising an electrically-powered heating arrangement and a chamber for receiving the aerosol-generating article; wherein on the aerosol-generating article being operably positioned in the chamber, the heating arrangement and aerosol-generating article are aligned relative to each other such that the heating arrangement is positioned to overlie a greater percentage proportion of the downstream portion of the cavity than the upstream portion of the cavity.

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