Heating assembly for an aerosol generating device - Patent application

Abstract

There is provided a heating assembly (10) for an aerosol generating device comprising an elongated heating cup (12) having a tubular wall (14) defining a cavity for receiving a tubular aerosol generating article therein, and a resistive heater (16) arranged for heating upon application of an electric current, the resistive heater being arranged in thermal communication with an outer surface of the tubular wall, the tubular wall having a continuous, circumferentially alternating distribution of substantially planar wall portions (14a) and convex wall portions (14b) about its circumference, the number of substantially planar wall portions being three or more, the substantially planar wall portions being substantially planar on both the outer and inner surfaces of the tubular wall. Also provided is an aerosol generating device comprising such a heating assembly, and a system comprising the aerosol generating device.

Description

[Technical field]

[0001] The present disclosure relates to a heating assembly for an aerosol generating device. Also provided is an aerosol generating device with such a heating assembly, and a system including the aerosol generating device. The present disclosure is particularly applicable to portable aerosol generating devices, which may be self-contained and low-temperature. Such devices may heat tobacco or other suitable material by conduction, convection, and / or radiation, rather than by combustion, to generate an aerosol for inhalation. The heating assembly according to the present invention is safe, reliable, easy to manufacture, and has low power requirements. [Background technology]

[0002] The popularity and use of risk reduction or risk modification devices (also called vaporizers) has grown rapidly in recent years as an aid to assist habitual smokers who wish to quit smoking traditional tobacco products such as cigarettes, cigars, cigarillos and rolling tobacco. A variety of devices and systems are available that heat or warm an aerosolizable substance, as opposed to burning tobacco in traditional tobacco products.

[0003] A commonly available risk reduction or risk modification device is the substrate heated aerosol generating device or the heat-not-burn device. This type of device generates an aerosol or vapor by heating an aerosol generating article, which typically includes moist tobacco or other suitable aerosolizable material, to a temperature typically in the range of 150°C to 350°C. By heating the aerosol generating article rather than burning or combusting it, an aerosol is released that includes the ingredients desired by the user but without the toxic and carcinogenic by-products of combustion and burning. Furthermore, since the aerosol generated by heating tobacco or other aerosolizable material typically does not include the burnt or bitter taste resulting from burning and burning that can be unpleasant to the user, the substrate therefore does not require the sugars and other additives typically added to such materials to make the smoke and / or vapor more palatable to the user.

[0004] However, thermal management of aerosol generating devices can prove problematic, especially during periods of frequent or prolonged use. Furthermore, the power required to heat the aerosol generating article can be quite high, necessitating frequent recharging or replacement of batteries in conventional devices. It is also desirable to simplify the manufacture of aerosol generating devices. Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to address the above problems and provide an aerosol generating device with improved safety and reduced power requirements. [Means for solving the problem]

[0006] According to a first aspect of the present invention, there is provided a heating assembly for an aerosol generating device comprising an elongated heating cup having a tubular wall forming a cavity for receiving a tubular aerosol generating article therein, and a resistive heater arranged for heating upon application of an electric current, the resistive heater being arranged in thermal conductivity to an outer surface of the tubular wall, the tubular wall having a continuous, circumferentially alternating distribution of substantially planar and convex wall portions around its circumference, the number of substantially planar wall portions being three or more, and the substantially planar wall portions being substantially planar on both the outer and inner surfaces of the tubular wall.

[0007] Thus, a tubular aerosol-generating article, such as a tobacco stick, can be inserted into the heating cup of the heating assembly and heated using a resistive heater to release an aerosol. The aerosol can then be inhaled by a user. As explained below, such heating assemblies require a lower overall temperature to generate these aerosols and therefore require less power to operate. In addition, the heating assemblies are convenient to manufacture and simple to use.

[0008] The substantially planar wall is preferably a flat, planar portion of the tubular wall extending longitudinally along the length of the heating cup. The substantially planar wall may extend in a tangential plane - i.e., a plane perpendicular to a radial direction extending outward from the centerline and parallel to the longitudinal axis of the heating cup.

[0009] By "substantially planar" it is understood that substantially planar walls are generally flat and planar across their entire surface. In particular, substantially planar walls will be significantly flatter than the intervening convex walls. However, substantially planar walls may still include small curvatures and / or small surface reliefs. In a preferred example, the substantially planar walls are planar (i.e. flat) such that the outer and inner surfaces of the tubular wall are planar.

[0010] In contrast, a convex wall portion located between and joining substantially planar walls may be curved or define an interior angle. For example, a convex wall portion may extend circumferentially between two adjacent substantially planar walls. Adjacent substantially planar walls are preferably connected by a convex wall portion such that there is a corresponding number of substantially planar walls and convex walls. Thus, when considering the outer surface of the tubular wall, it will be understood that the convex wall portion is convex.

[0011] The distance between opposing substantially planar walls is typically less than the distance between opposing convex walls, such that an aerosol-generating article inserted into the heating cup cavity will tend to contact the substantially planar walls rather than the convex walls.

[0012] Indeed, the substantially planar walls are preferably configured to contact the aerosol-generating article during use and can grip (i.e., secure or hold) the aerosol-generating article in a predetermined position within the cavity of the heating cup. The three or more substantially planar walls spaced around the tubular wall precisely and stably secure the article in the appropriate position. Thus, the tubular aerosol-generating article is easily aligned and centered within the heating cup by the three or more substantially planar walls. It is therefore easy for the user to correctly insert the aerosol-generating article into the heating cup. The heating assembly is therefore safe and easy to use.

[0013] The resistive heater is provided on the tubular wall, and as used herein the term "on" is understood to mean in contact with or on the underlying component. Good heat transfer is achieved between the aerosol-generating article and the resistive heater. Heat can be transferred rapidly by conduction from the resistive heater through the tubular wall to the aerosol-generating article. This heat transfer is particularly rapid through a substantially planar wall that contacts or grips the aerosol-generating article. This can reduce the maximum overall temperature of the heating assembly, thereby minimizing the power required to heat the aerosol-generating article and improving safety.

[0014] The resistive heater is preferably configured to raise the temperature of the aerosol-generating article received within the heating cup cavity to a temperature between 150° C. and 350° C., more preferably between 190° C. and 310° C., and more preferably even between 230° C. and 260° C. These temperatures are well suited for generating aerosols from a variety of aerosolizable materials, including moist tobacco.

[0015] In addition, it will be appreciated that a tubular heating cup having alternating substantially planar and convex walls is simple to assemble and may be quickly and conveniently manufactured.

[0016] By "disposed in thermal conduction" it is understood that heat may be transferred by conduction between the resistive heater and the exterior tubular wall. Thus, the resistive heater may be disposed on the tubular wall and in direct thermal contact therewith. Thus, the resistive heater may be provided in direct contact with the tubular wall or above the tubular wall, in which case the resistive heater and the tubular wall may be separated by an intervening layer, such as an electrically insulating layer. Thus, no gaps or voids exist between the resistive heater and the tubular wall. This ensures good heat transfer between the resistive heater and the tubular wall.

[0017] Preferably, the substantially planar wall portions are evenly distributed around the circumference of the tubular wall. In other words, the substantially planar wall portions are preferably (but not necessarily) consistently spaced around the circumference of the tubular wall. This rotationally symmetric arrangement simplifies production of the tubular wall. Furthermore, an aerosol-generating article received within the heating assembly can be easily positioned and secured to the center of the elongated heating cup. As a result, the aerosol-generating article can be evenly heated by the heating assembly. This reduces the power requirements of the heating assembly and maximizes the life of the aerosol-generating article.

[0018] In a preferred embodiment, the number of substantially planar walls is between 3 and 5. An elongated heating cup with a tubular wall having three planar areas (spaced apart by three convex walls) provides a particularly stable positioning of the aerosol-generating article. Heating cups that may comprise a tubular cup with a greater number of substantially planar walls are possible as well. However, the manufacture of these elongated heating cups with a greater number of substantially planar walls is more complicated, in part because the heater track applied to the surface of the tubular wall (e.g. the planar walls) must be reduced in size and / or must span a greater number of walls.

[0019] In a particularly preferred embodiment, each substantially planar wall is covered by a respective resistive track of the heater. Thus, the resistive track of the heater overlies each substantially planar wall, said resistive track being provided in direct contact with or above the planar outer surface of each substantially planar wall. The resistive track is configured to heat up when an electric current is passed through it. Thus, heat from the resistive track can be rapidly transferred to an aerosol-generating article fixed or gripped by the planar wall. This arrangement is very efficient. By providing the resistive track of the heater adjacent to the point where the elongated heating cup contacts the aerosol-generating article, rapid heat transfer is possible. Therefore, by arranging the resistive track on the outer surface of the substantially planar wall portion, the overall temperature required for the heating assembly to heat the elongated heating cup is reduced, reducing the power requirements of the heating assembly.

[0020] The resistive tracks of the different substantially planar walls may be arranged in series or in parallel. In such an example, the resistive tracks form part of a single resistive circuit. Alternatively, however, the heating assembly may comprise a number of separate resistive circuits. For example, each circuit may comprise a resistive track provided on a respective substantially planar wall.

[0021] Preferably, the resistive tracks of the different substantially planar walls are connected by lower resistance connecting tracks, which have a lower electrical resistance than the resistive tracks covering the substantially planar walls and therefore preferably do not generate a large amount of heat when supplied with current, thus making it possible to save power and only at the substantially planar walls a large amount of heat is applied to the heating cup (which provides a particularly efficient heat transfer as explained above).

[0022] The lower resistance connection tracks are preferably located on the convex wall portions, in other words the connection tracks are arranged in contact with or above the convex wall portions. The resistive tracks of each substantially planar wall portion can thus be spaced apart around the periphery of the tubular wall by connection tracks that extend across the intervening convex wall portions. In this way the lower resistance connection tracks can electrically connect adjacent resistive tracks to form an electrical circuit around the periphery of the tubular wall.

[0023] It will thus be appreciated that the heating assembly may comprise a number of resistive tracks and less resistive connecting tracks corresponding to the number of substantially planar and convex wall portions, respectively, and furthermore the resistive tracks and less resistive connecting tracks may be arranged consecutively and alternatingly around the tubular wall in a manner corresponding to the substantially planar and convex wall portions.

[0024] Preferably, the lower resistance connection tracks are wider than the resistive tracks on the substantially planar wall portions, so that the wider tracks of the lower resistance connection tracks have a lower electrical resistance than the resistive tacks and are unable to generate large amounts of heat, even when made of the same material as the resistive tracks.

[0025] The resistive tracks and the connecting tracks together form the heating tracks of the resistive heater. The overall electrical resistance of these heating tracks may be 0.5-1.5 ohms, more preferably 0.8-1.2 ohms, more preferably even 1.0-1.1 ohms. In a particularly preferred embodiment the overall resistance of the resistive heater is 1.05 ohms.

[0026] Preferably, the tubular wall comprises a metal or metal alloy of substantially constant thickness. Metals and metal alloys have good heat transfer properties and can rapidly transfer heat from the resistive heater to the aerosol-generating article in the heating assembly. Suitable materials include stainless steel, steel, aluminum and copper. Forming the tubular wall from a material having a substantially constant thickness simplifies manufacturing, especially when the tubular wall is formed from a metal. In a preferred example, the tubular wall comprises stainless steel having a thickness of 1 mm.

[0027] In a preferred example, the heater is formed as a thin film wrapped around the tubular wall of the elongated heating cup. Such a thin film heater can be provided with the resistive tracks and lower resistance connecting tracks described above and can be easily manufactured separately from the tubular wall and then applied (e.g., using an adhesive or a heat shrink film) to the outer surface of the tubular wall in a suitable arrangement. This approach is particularly advantageous since the heater can be conveniently manufactured in a flat or planar form before being applied (i.e., wrapped) around the tubular wall. For example, the resistive heater can be a thin film heater manufactured according to the methods and techniques described in PCT / EP2020 / 074150 (claiming priority from European Patent Application Publication No. 19196024.4) or PCT / CN2019 / 104804, the disclosures of which are incorporated herein by reference.

[0028] In a similarly preferred embodiment, the resistive heater comprises heating tracks printed directly on the outer surface of the tubular wall. These heating tracks may include any of the resistive tracks and lower resistance connecting tracks described above and can be quickly and conveniently applied directly to the tubular wall. Printing the heating tracks in this manner is quick and minimizes material waste. In some preferred embodiments, the heating tracks can be printed directly on the tubular wall such that the heating tracks are provided in contact with the outer surface of the tubular wall. However, in further embodiments, an intervening layer (e.g. an electrically insulating layer) can be provided between the heating tracks and the tubular wall such that the heating tracks are located above the surface of the tubular wall.

[0029] Alternatively, the resistive heater may comprise a number of separate thin film segments, each supporting a single resistive track, each applied on or above a corresponding substantially planar wall. In a further example, the heating tracks may be applied to the heating cup using a transfer.

[0030] In some preferred embodiments, the tubular wall has an electrically insulating layer thereon. Preferably, the electrically insulating layer is a coating or polymer film, although alternative dielectric materials may be used.

[0031] An electrical insulating layer can separate the resistive heater from the tubular wall. Thus, the electrical insulating layer can be provided on the outer surface of the tubular wall between the tubular wall and the heating track described above. This may be necessary when the tubular wall is formed of an electrically conductive material. In these instances, the resistive heater can be provided in contact with the electrical insulating layer so as to maintain thermal conductance with the underlying tubular wall.

[0032] If the heater is a thin film heater, the electrically insulating layer may be a dielectric backing film (i.e., carrier film) onto which the heater tracks are first applied, and the thin film heater is wrapped or applied around the tubular wall such that the backing film is disposed between the resistive tracks and the tubular wall. Alternatively, the electrically insulating layer may be applied to the exterior surface of the tubular wall after the tubular wall is formed and before the heating tracks are printed onto the tubular wall.

[0033] In a further example, an electrically insulating layer may additionally or alternatively be provided over the resistive heater to cover and protect the underlying heating tracks, for example if the heater is a thin film heater then a further dielectric film may be provided over and surround the heater tracks.

[0034] In a preferred embodiment, the flat or substantially flat wall ends before the bottom wall of the heating cup, and the distance between the bottom wall of the heating cup and the end of the flat or substantially flat wall is at least 2 mm. This may allow air to circulate at the closed bottom wall of the heating cup. This may allow for more consistent heat distribution through the heating cup during use.

[0035] Preferably, the planar or substantially planar wall is configured to compress an aerosol-generating article received in the heating cup at the location of the substantially planar wall. As a result, the aerosol-generating article is securely held in the heating cup. Furthermore, due to the increased contact area between the aerosol-generating article and the substantially planar wall, heat may be transferred more quickly from the planar wall (and any overlying resistive track) to the aerosol-generating article. Thus, an aerosol generating device incorporating a heating assembly according to the present invention may be easier to use and may require less power.

[0036] In a preferred example, the convex wall defines an air flow path between the aerosol-generating article received in the heating cup and the heating cup. Thus, a gap or void through which air can flow can be defined between the convex wall and the aerosol-generating article received in the heating cup. This void can extend longitudinally along the heating cup. The flow of air along this air flow path can allow heat to be transferred through the heating cup during use. Thus, the temperature distribution within the heating cup can be more consistent. This can reduce or avoid localized hot and cold spots, improving both the efficiency, safety and taste of the aerosol generated by the aerosol-generating article.

[0037] According to a further aspect of the present invention, there is provided a system comprising an aerosol generating device comprising a heating assembly according to the previous aspect of the present invention, and an aerosol-generating article configured to be inserted into the cavity such that the aerosol-generating article is compressed at the planar or substantially planar wall.

[0038] The aerosol generating device in this system requires reduced power and lower internal temperatures to generate the aerosol from the aerosol-generating article, and therefore can be made safer, more compact, and more reliable.

[0039] The system may include a heating assembly that includes any of the optional or preferred features described above, such that the system can provide any of the corresponding benefits described above.

[0040] The aerosol generating device may include various additional features. These may include a power source (e.g., a battery), one or more temperature sensors, a controller, and insulation. The temperature sensor may be configured to measure the temperature of the resistive heater, the aerosol generating device, and / or the internal temperature of the heating cup. The controller may be configured to control or regulate the operation of the resistive heater - for example, by controlling the power provided to the heater from the power source. The controller may be configured to control the operation of the resistive heater based on measurements received from the temperature sensor described above. Insulation may be disposed around the heating assembly and configured to limit or reduce the flow of heat away from the heating cup. The aerosol generating device may thus be more efficient and safer.

[0041] The aerosol-generating article is preferably tubular. In a preferred embodiment, the aerosol-generating article is a tobacco stick or an equivalent article.

[0042] Specific examples of the present invention will now be described with reference to the following figures: [Brief description of the drawings]

[0043] [Figure 1] 1 shows two perspective views of a heating assembly according to the present invention. [Diagram 2] 1 shows a schematic cross-section of a heating assembly according to one embodiment of the present invention. [Figure 3a] 1 shows a schematic cross-section of an aerosol generating device comprising a heating assembly according to the present invention. [Figure 3b] 3 shows a schematic cross-section of a system according to one embodiment of the invention, the system comprising an aerosol generating device as shown in FIG. 3a and an aerosol-generating article. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] 1a and 1b show perspective views of a heating assembly 10 configured to receive and heat an aerosol-generating article (e.g., a tubular aerosol article such as a tobacco stick). The aerosol-generating article heated using the heating assembly 10 will emit an aerosol that can then be inhaled by a user.

[0045] The heating assembly 10 comprises an elongated heating cup 12 having an open end 12a and an opposed closed bottom end 12b provided with a bottom wall. A tubular wall 14 extends between the open end 12a and the bottom end 12b. The tubular wall 14 and the bottom end 12b define an interior cavity configured to receive an aerosol-generating article. The tubular aerosol-generating article may be partially or wholly inserted into the heating cup 12 through the open end 12a such that it is concentrically surrounded by the tubular wall 14.

[0046] As can be seen, the heating cup 12 includes a lip 12c at its open end 12a. The lip 12c is flared and extends radially outward from the tubular wall 14. The flared lip 12c allows for easy insertion of an aerosol-generating article into the heating cup 12 during use. However, such a lip at the rim of the cup is not required, and other embodiments of the invention may not include a lip.

[0047] The tubular wall 14 has a substantially constant thickness around its circumference and comprises three planar wall portions 14a and three convex wall portions 14b. The planar wall portions 14a and the convex wall portions 14b are alternately distributed around the circumference of the tubular wall 14 such that each planar wall portion 14a is separated from the remaining planar wall portions 14a by the convex wall portions 14b (and vice versa). As can be seen in FIG. 1a, the planar wall portions 14a are planar on both the outer and inner surfaces of the tubular wall 14. The planar wall portions 14a and the convex wall portions 14b are consistently sized such that the planar wall portions 14a are evenly distributed around and about the circumference of the tubular wall 14.

[0048] A tubular aerosol-generating article inserted into the cavity of the heating cup 12 can be held in contact with the planar wall 14a, which compresses and deforms the aerosol-generating article locally at the contact points between the aerosol-generating article and the inner surface of the planar wall 14a. Thus, the aerosol-generating article can be securely held within the heating cup 12, and good thermal conduction can be achieved between the planar wall 14a and the aerosol-generating article.

[0049] The heating assembly 10 further comprises a resistive heater 16 disposed about the exterior (i.e., outer surface) of the tubular wall 14 of the heating cup 12. The resistive heater 16 is disposed in direct thermal contact with the tubular wall 14 of the heating cup 12 and is configured to apply heat through the tubular wall 14 of the heating cup 12 to the interior cavity within the aerosol-generating article (and any aerosol-generating article contained therein). As can be seen from the figure, the resistive heater 16 is disposed in thermal communication with the exterior surface of the tubular wall 14, with the resistive heater 16 disposed on a surface of the tubular wall 14 such that heat may be conducted between the resistive heater and the tubular wall 16.

[0050] Specifically, as shown, the resistive heater 16 comprises three conductive resistive tracks 16a connected by three conductive, less resistive connecting tracks 16b, the resistive tracks 16a being connected in series by the less resistive connecting tracks 16b (although this is not required).

[0051] Each of the three resistive tracks 16a is provided on a respective planar wall portion 14a of the tubular wall 14. Thus, each resistive track 16a is in thermal contact with the respective planar wall portion 14a that it covers. The resistive tracks 16a are configured to heat up through resistive heating when an electric current flows through them. This heat is transferred to the adjacent planar wall portion 14a and through the planar wall portion 14a to the interior of the heating cup 12. Thus, an aerosol-generating article inserted into the heating cup 12 will be efficiently heated by the heating assembly 10 since the article is in strong thermal contact with the resistive tracks 16a through the tubular wall 14 and the resistive tracks 16a are located on or above (i.e. adjacent to) the planar wall portion 14a where the aerosol-generating article contacts the heating cup 12.

[0052] Three lower resistance connecting tracks 16b are each provided between two adjacent resistive tracks 16a on each convex wall portion 14b of the tubular wall 14. As can be seen, the connecting tracks 16b have significantly larger dimensions than the resistive tracks 16a, being wider and thicker than the resistive tracks 16a. The connecting tracks 16b therefore have a lower resistance than the resistive tracks 16a and do not significantly heat the convex wall portion 14b during use.

[0053] As can be seen in FIG. 1, the planar wall 14a and the convex wall 14b extend along substantially the entire length of the tubular wall 16 and the majority of the length of the heating cup 12, respectively. As shown, the planar wall 14a and the convex wall 16b extend between the closed bottom end 12b of the heating cup 12 and the flared lip 12c of the open end 12a of the heating cup 12. These planar walls 14a extending along substantially the entire length of the tubular wall 16 and the majority of the length of the heating cup 12 allow rapid and consistent transfer of heat to the contents of the heating cup 12 along the entire length of the heating cup 12. This reduces energy requirements and provides consistent aerosol generation.

[0054] In a preferred embodiment of the invention, the planar wall portion 14a and / or the convex wall portion 14b extend along at least 75%, more preferably at least 80%, more preferably even at least 90% of the length of the heating cup 12 (but this is not required). Similarly, the planar wall portion 14a and / or the convex wall portion 14b extend along at least 75%, more preferably at least 80%, more preferably even at least 90% of the length of the tubular wall 16 (but this is not required).

[0055] FIG. 2 shows a schematic version of a heating assembly 20 in cross-section. The cross-section extends in a plane perpendicular to a longitudinal axis through the heating assembly 20. This heating assembly 20 shares many features and advantages with the heating assembly 10 shown in FIGS. 1a and 1b. The heating assemblies 10, 20 in these figures operate in the same manner and have similar constructions. The reference numbers of features shared between the two examples are incremented by 10 between the figures.

[0056] The heating assembly 20 comprises a heating cup 22 with an internal cavity 28 into which a tubular aerosol-generating article may be inserted. The heating cup 22 comprises a tubular wall 24 which defines the circumferential boundary of the cavity 28. Provided about the tubular wall 24 is a resistive heater comprising alternating electrically conductive resistive tracks 24a and lower resistance connecting tracks 24b. As can be seen, the resistive heater is disposed in thermal communication with the outer surface of the tubular wall 24 (i.e. the surface of the tubular wall 24 opposite the cavity).

[0057] The tubular wall 24 comprises three planar wall portions 24a and three curved convex wall portions 24b. The planar wall portions 24a and the convex wall portions 24b are alternately arranged around the circumference of the tubular wall 24 such that a convex wall portion 24b is positioned between each planar wall portion 24a (or vice versa) around the circumference of the tubular wall 24. The planar wall portions 24a and the convex wall portions 24b are consistently (i.e., evenly) distributed around the circumference of the tubular wall.

[0058] As can be seen in Figure 2, the cup 20 includes a lip 22c that extends around the tubular wall 24. As in Figure 1, the lip 22c is located at the open end of the heating cup 22. The cross section shown in Figure 2 is looking towards this open end of the heating cup. As such, the lip 22c is seen to surround the tubular wall 24 of the cup 20 in cross section. The lip 22c is preferably flared to facilitate insertion of an aerosol-generating article into the cup 12 during use. Having said this, it will be understood that the lip 22c is optional and not essential to the operation of the resistive heater 26 described below.

[0059] An exemplary cross-section of an aerosol-generating article that may be heated using the heating assembly 20 in an uncompressed state prior to insertion into the heating assembly 20 is shown by dashed line A. As can be seen, the article in an uncompressed state has a circular cross-section, and is preferably substantially cylindrical (although this is not required and the heating assembly according to the present invention can be configured to receive and operate with aerosol-generating devices of various shapes). The cross-section of the article is large enough that the article cannot be contained within the cavity 28 without contacting the planar wall 24a of the tubular wall 24. Instead, when inserted into the heating cup 22 (i.e., into the cavity 28), the planar wall 24a will contact the aerosol-generating article and push against it. This force will deform the aerosol-generating article such that the aerosol-generating article is locally compressed against the planar wall 24a.

[0060] The deformation of the aerosol-generating article after the article is inserted into the heating cup 12 is shown diagrammatically by dashed line A'. As can be seen, the article (originally of substantially circular cross-section as indicated by line A) is locally compressed against the planar wall 24a of the tubular wall 24 such that the exterior of the article in this compressed state fits and conforms to the inner surface of the planar wall 24a of the tubular wall 24. This deformation increases the shared contact surface between the article and the planar wall 24a, ensuring that heat can be rapidly transferred between the article and the planar wall 24a.

[0061] It will be appreciated that the aerosol-generating article, as indicated by dashed lines A and A', is not locally compressed in the convex wall 24b, which is located at a greater radial distance from the center of the heating cup 24 than the flat wall 24a. In these regions, the outer surface of the article will substantially follow its original uncompressed shape, as indicated by line A. Thus, empty channels 28a may be left between the article and each convex wall 24b. These empty channels 28a (i.e., the gap between the article and the convex wall 24b) define air flow paths that extend longitudinally along the heating assembly between the article and the heating cup 22. During use, air can flow along these empty channels 28a to ensure consistent distribution of heat throughout the article in the cavity 28 and the heating cup 22. This ensures consistent aerosol generation and reduces energy requirements.

[0062] It will be appreciated that the planar wall portion 14a of the heating cup 12 described above with reference to Figures 1a and 1b will compress an aerosol-generating article received therein in a similar manner.

[0063] The resistive heater 26 comprises three conductive resistive tracks 26a connected by three conductive lower resistance connecting tracks 26b.

[0064] Each of the three resistive tracks 26a covers a respective planar wall portion 24a of the tubular wall 24. As shown, each resistive track 26a is in direct thermal contact (i.e., thermal conduction) with the respective planar wall portion 24a and with any aerosol-generating article inserted in the heating assembly 20. The resistive tracks 26a are configured to heat up through resistive heating when an electric current is passed through them. This heat is transferred to the adjacent planar wall portion 24a and through the planar wall portion 24a to the interior of the heating cup 22. An aerosol-generating article in the heating cup 22 that is compressed by the planar wall portion (e.g., an aerosol-generating article having a cross section coinciding with dashed line A) can be heated rapidly in this way. Thus, the overall temperature of the resistive heater and its power requirements can be reduced.

[0065] Three lower resistance connection tracks 26b are each provided between two adjacent resistive tracks 26a on each convex wall portion 24b of the tubular wall 24. The connection tracks 26b therefore have a lower resistance than the resistive tracks 26a and preferably do not significantly heat the convex wall portion 24b during use. As shown, the bottom left connection track 26b comprises an electrical connection 29 by which the resistive heater can be connected to further electronic components (e.g. a battery and / or a controller).

[0066] The air flow through the heating cup, and therefore the heat distribution through the heating cup, may be further improved if the planar wall portion (which, as explained above, contacts the aerosol-generating article when inserted into the heating cup) terminates short of the closed end of the heating cup. For example, as shown in Figures 1a and 1b, the planar wall portion 14a terminates about 2 mm short of the bottom wall 12b of the heating cup. In such an example, air can circulate around the end of the aerosol-generating article that is inserted furthest into the heating cup and through empty channels defined between the aerosol-generating article and the different convex wall portions.

[0067] In each of the examples described above with reference to Figures 1a, 1b and 2, the heating assemblies 10, 20 can be made of a variety of materials. Stainless steel with a thickness of 1 mm is particularly preferred for use as the tubular walls 14, 24 of the heating cups 12, 22, as it is cheap, easy to process and offers good thermal properties. The heating tracks (i.e. the resistive tracks 16a, 26a and the connecting tracks 16b, 26b) can be made of any suitable electrically conductive material. Preferably, the heating tracks of each heating assembly 10, 20 have a total resistance of 0.5 to 1.5 ohms, preferably 0.8 to 1.2 ohms, more preferably even 1.0 to 1.1 ohms. As shown in each of the figures described above, the heating tracks of the resistive heaters 16, 26 are provided directly on the outer surface of the tubular walls 14, 24. However, this is not required. In a further example, an electrically insulating layer (e.g. a film or coating) may be provided between the tubular walls 14, 24 and the resistive heaters 16, 26.

[0068] It will be appreciated that the examples of heating cups 12, 22 described above with reference to Figures 1 and 2 avoid relatively sharp protrusions that extend radially inward toward the center of the heating cups 12, 22. Although these radial protrusions can be used to grip or position an aerosol-generating article within the heating cup, their use can result in significant localized deformation of the aerosol-generating article and poor distribution of heat with localized "hot spots" or "hot zones" around the protrusions. In addition, greater forces may be required to insert and remove the article.

[0069] Instead, it will be noted from Figures 1 and 2 that the convex wall portions 14b, 24b and the planar wall portions 14a, 24a are alternately positioned around the tubular wall 24. Moreover, the convex wall portions 14b, 24b and the planar wall portions 14a, 24a extend continuously and alternately around the tubular wall 14, 24 and are adjacent to each other. It will thus be seen that each convex wall portion 14b, 24b is connected or merged along each of its longitudinal edges with the adjacent planar wall portions 14a, 24a. Similarly, each planar wall portion 14a. 14b is connected or merged along each of its longitudinal edges with the adjacent convex wall portions 14b, 24b. In other words, no further wall portions are provided between the convex wall portions 14b, 24b and the adjacent planar wall portions 14a, 24a.

[0070] Moreover, as can be most easily seen in Figure 2, the convex wall portions 14b, 24b are arcuate having a cross section that follows a circular circumference, while the planar wall portions 14a, 24a extend between adjacent arcuate convex wall portions 14b, 24b and extend along a chord of a circle defined by the convex wall portions 14b, 24b. Thus, there are no radial projections or radial walls extending from the tubular walls 14, 24 toward the center of the cavity 28.

[0071] While the above features are not required, avoiding additional walls and any radial protrusions helps ensure rapid transfer of heat to the aerosol-generating articles in the heating cup 12, 22 and consistent heat distribution throughout the aerosol-generating articles, thereby reducing energy requirements.

[0072] Moreover, as can be seen from both Figures 1 and 2, the circumferential distribution and dimensions of the planar wall portions 14a, 24a and the convex wall portions 14b, 24b are similar. The planar wall portions 14a, 24a are provided on approximately half of the circumference of the heating cup 12, 22, and the convex wall portions 14b, 24b are also provided on approximately half of the circumference of the heating cup 12, 22. In other words, approximately half of the tubular wall 14, 24 of the heating cup 12, 24 is defined by the planar wall portions 14a, 24a, while the remaining part of the circumference is defined by the convex wall portions 14b, 24b. Indeed, in a preferred embodiment of the present invention, the planar walls may combine to cover approximately 30-70% of the circumference of the heating cup, more preferably 40-60% of the circumference, more preferably 45-55% of the circumference. Similarly, in preferred embodiments, the convex wall portion may span approximately 30-70% of the circumference of the heating cup, more preferably 40-60% of the circumference, and more preferably 45-55% of the circumference. These arrangements provide for rapid and consistent heat flow from the heating assembly to its contents (e.g., an aerosol-generating article received within the heating assembly), thereby reducing energy requirements.

[0073] Further, as explained, the heating cups 12, 22 shown in Figures 1 and 2 include planar walls 14a, 24a. As shown, these planar walls 14a, 24a are planar (i.e., flat) and extend tangentially to the longitudinal axis of the heating cups 12, 22 such that the inner and outer surfaces of the tubular walls 14, 24 are planar. However, in further examples, the planar walls can be replaced with substantially planar walls in which any of these surfaces of the tubular walls 14, 24 are slightly curved or include a surface relief.

[0074] 1 and 2 show the heating cup having three planar walls 14a, 24a and three convex walls 14b, 24b, this is not required, and further embodiments may include alternative numbers of planar and convex walls (e.g., four, five or more planar and / or convex walls).

[0075] Figures 3a and 3b illustrate generally a system 100 according to the present invention. System 100 comprises an aerosol generating device 110 and an aerosol-generating article 120 that can be inserted into aerosol generating device 110. Figure 3a shows the aerosol generating device 110 alone, while Figure 3b shows the complete system in which the aerosol-generating article 110 is received within device 120.

[0076] The aerosol generating device 110 comprises a heating assembly 111 comprising a heating cup 112 and a resistive heater 113. The heating assembly 111 may follow any of the examples described with reference to Figures 1a, 1b and 2 and may include preferred or optional features described above.

[0077] The aerosol-generating device includes an aerosolizable material, such as moist tobacco, and a heating assembly 111 configured to heat the aerosol-generating article 120 to generate an aerosol when the aerosol-generating article 120 is inserted into the heating cup 112 (as shown in FIG. 3b).

[0078] In addition, the aerosol generating device 110 comprises a controller 114, a battery 115, and a thermal insulation layer 116 disposed around the heating assembly 111. The resistive heater 113, the controller 114, and the battery 115 are in electrical communication as shown by the lines in FIG. 3a. The battery 115 is configured to provide power to the resistive heater 113. The controller 114 is configured to control the heat provided by the resistive heater 113 to the heating cup 112 to regulate the internal temperature of the heating cup 112 and thus control the amount of aerosol formed using the system. The controller 114 can control this heat by varying the power provided by the battery 115 to the resistive heater 113. This control may be empirical or based on pre-determined parameters. However, more preferably, the control is based on measurements made by a thermistor or other temperature sensor configured to measure the temperature of the resistive heater 113, the heating cup 112, and / or the aerosol-generating article 120 when received in the heating cup 112. For example, the controller 114 may use a closed-loop control process to maintain the temperature of the heating cup 112 at a predetermined level.

[0079] 3b, the aerosol-generating article 120 is longer than the heating cup 112 and therefore extends out from the aerosol generating device 110. A user can inhale aerosol from this free tip of the aerosol-generating article 120. However, this is not required and in a further example, the aerosol-generating article 120 may be received entirely within the heating cup 112, in which case the aerosol generating device may include a cap and / or mouthpiece configured to close the open end of the heating cup 112.

Claims

1. An elongated heating cup comprising a tubular wall forming a cavity for receiving a tubular aerosol generating article therein, a resistive heater arranged to heat upon application of an electric current, and comprising, wherein the resistive heater is arranged to conduct heat to an outer surface of the tubular wall, wherein the tubular wall has a substantially planar wall portion and a convex wall portion continuously and alternately distributed circumferentially around the tubular wall, the number of substantially planar wall portions being three or more, wherein the substantially planar wall portion is substantially planar on both the outer surface and the inner surface of the tubular wall, a heating assembly for an aerosol generating device.

2. The substantially planar wall portions are evenly distributed around the tubular wall, The heating assembly according to claim 1.

3. The number of the substantially planar wall portions is three to five, The heating assembly according to claim 1 or 2.

4. Each substantially planar wall portion is covered by a resistive track of the heater, The heating assembly according to any one of claims 1 or 2.

5. The resistive tracks of different substantially planar wall portions are installed in series or in parallel, The heating assembly according to claim 4.

6. The resistive tracks of different substantially planar wall portions are connected by a lower resistance connection track, The heating assembly according to claim 4.

7. The lower resistance connection track is located on the convex wall portion, The heating assembly according to claim 6.

8. The lower resistance connection track is wider than the resistive track on the substantially planar wall portion, The heating assembly according to claim 6.

9. The tubular wall comprises a metal or metal alloy of substantially constant thickness, The heating assembly according to claim 1 or 2.

10. The resistive heater is formed as a thin film wound around the tubular wall of the heating cup, The heating assembly according to claim 1 or 2.

11. The resistive heater comprises a heating track printed on the outer surface of the tubular wall, The heating assembly according to claim 1 or 2.

12. The tubular wall has an electrical insulation layer on the tubular wall, The heating assembly according to claim 1 or 2.

13. The electrical insulation layer is a coating or a polymer film, The heating assembly according to claim 12.

14. The substantially planar wall portion ends in front of the bottom wall of the heating cup. The distance between the bottom wall of the heating cup and the end of the substantially planar wall portion is at least 2 mm. The heating assembly according to claim 1 or 2.

15. The substantially planar wall portion is configured to compress an aerosol-generating article received within the heating cup at the location of the substantially planar wall portion. The heating assembly according to claim 1 or 2.

16. The convex wall portion defines an air flow path between the aerosol-generating article received within the heating cup and the heating cup. The heating assembly according to claim 1 or 2.

17. An aerosol-generating device comprising the heating assembly according to claim 1 or 2, and the aerosol-generating article configured to be inserted into the cavity such that the aerosol-generating article is compressed at the location of the substantially planar wall portion. A system comprising.

Images