Tobacco substrates for use in aerosol generating devices, consumable articles, and related manufacturing and optimization methods

Abstract

The present invention relates to a tobacco substrate (25) for use in an aerosol generating device, the substrate comprising a first conductive surface (34A) including air flow passages (41, 51) formed in recesses on the first conductive surface (34A); the air flow passage (41, 51) includes a flow inlet (42, 52A, 52B), a flow outlet (43A, 43B, 53), and a flow groove extending along the first conduction surface (34A) between the flow inlet (42, 52A, 52B) and the flow outlet (43A, 43B, 53); The width and / or depth and / or cross-sectional shape of the flow grooves vary along the length of the flow grooves; The tobacco substrate (25).

Description

[Technical field]

[0001] The present invention relates to a tobacco substrate for use in an aerosol generating device, comprising at least one air flow path. The tobacco substrate according to the invention may be used as such or may be part of a consumable article within the meaning of the present invention.

[0002] In particular, tobacco substrates according to the present invention are adapted to operate with aerosol-generating devices, also known as heat-not-burn or HNB devices, where these types of aerosol-generating devices are adapted to heat, rather than combust, the aerosol-generating substrate contained within the article.

[0003] The present invention also relates to manufacturing methods for producing such tobacco substrates, and optimization methods for optimizing the air channel configurations on the conduction surface of such tobacco substrates. [Background technology]

[0004] The popularity and use of risk reduction or risk modification devices (also known as vaporizers or aerosol generating devices) has grown rapidly in recent years as aids to assist habitual smokers wishing 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 a vaporizable material, as opposed to burning tobacco in traditional tobacco products.

[0005] A commonly available risk reduction or risk modification device is the heated non-burn device, also known as a substrate heated aerosol generating device, or HNB. This type of device typically generates an aerosol or vapor by heating an aerosol-generating substrate, typically comprising moist tobacco or other suitable vaporizable material, to a temperature typically ranging from 150°C to 350°C. By heating, rather than burning or combusting, the aerosol-generating substrate, an aerosol is released that contains the ingredients desired by the user, but does not contain the toxic and carcinogenic by-products of combustion and burning. Furthermore, the aerosol generated by heating tobacco or other vaporizable material typically does not contain the burnt or bitter taste resulting from combustion and burning, which can be unpleasant to the user. Thus, the substrate does not require sugars and other additives that are typically added to such materials to make the smoke and / or vapor more palatable to the user.

[0006] Some HNB devices can be adapted to work with consumable articles having reduced dimensions. Such articles can for example have a flat shape and form a substantially rectangular parallelepiped shape with a thickness of 1 or 2 mm. Their transverse and longitudinal dimensions can be comprised between 10 and 30 mm. Such shape and dimensions make these consumable articles more efficient in heat transfer for steam generation compared to rod-type formats.

[0007] Consumable articles operable with HNB devices generally include a tobacco substrate, which is substantially solid and may be made, for example, by compressing tobacco. Such tobacco substrates may define one or several air flow passages that conduct air flow during a vaping session. However, it has been recognized that the conduction of flow along such air flow passages may not be optimal, leading to uneven heating of the substrate and, as a result, to its suboptimal use. This may result in an unsatisfactory user experience. Summary of the Invention [Problem to be solved by the invention]

[0008] One of the aims of the present invention is to propose a tobacco substrate with improved airflow conducting properties, which leads to a more homogeneous heating of the substrate and an improved user experience. [Means for solving the problem]

[0009] To this end, the present invention relates to a tobacco substrate for use in an aerosol generating device, the tobacco substrate comprising a first conductive surface, the first conductive surface including an air flow passage formed in a recess on the first conductive surface. The air flow passage includes a flow inlet, a flow outlet, and a flow groove extending along the first conductive surface between the flow inlet and the flow outlet. The width and / or depth and / or cross-sectional shape of the flow groove varies along its length.

[0010] These features cause the cross-sectional dimensions and / or shape of the air flow passage to vary along its length. Thus, the conduction of air flow through the air flow passage can be optimized in a desired manner. This optimization can be based on different criteria, such as optimizing the flow rate, pressure drop, temperature and / or material properties across the tobacco substrate. For example, in some cases, it can be advantageous to form an air flow passage that has a larger cross-sectional dimension near the flow inlet compared to the cross-sectional dimension near the flow outlet. In this case, the air flow can be slowed down in the portion of the tobacco substrate adjacent to the flow inlet. This can lead to a more homogeneous heating of the tobacco substrate in this portion. Conversely, near the flow outlet, the cross-sectional dimensions of the air flow passage can be reduced so that the flow accelerates, thereby avoiding overheating of the substrate in the corresponding portion. Optimizing the cross-sectional dimensions of the air flow passage can also reduce the pressure drop along the substrate.

[0011] According to some embodiments, the first conductive surface includes a plurality of air flow channels.

[0012] These features result in several air channels being arranged on the same surface of the tobacco substrate. These air channels may be arranged in any suitable manner to allow the optimization of the air flow as described below. The air channels may, for example, run substantially parallel between themselves or may cross each other at one or several points. Furthermore, the cross-sectional dimensions and / or shapes of the air channels may vary according to the same or different laws. In this latter case, the laws may be independent or may be correlated between them. For example, one law may be deduced from another law. In a variant, it is not possible to associate a specific law with the variation of the cross-sectional dimensions and / or shapes of at least one air channel. In this case, these dimensions may, for example, be selected randomly within a predetermined interval of values.

[0013] According to some embodiments, at least one or each air flow channel comprises multiple flow outlets and / or multiple flow inlets.

[0014] These features allow at least some air channels to be split to form several flow inlets and / or several flow outlets. Furthermore, at least two air channels can share the same flow inlet and at least a common portion adjacent to this inlet. These air channels can then be split into two independent air channels with different flow outlets. Conversely, two air channels can be independent near their respective flow inlets and then merge to form a common flow outlet. In a variant, the two air channels can have a common flow inlet, a common flow outlet and two different flow grooves extending between the flow inlet and the flow outlet. Such an arrangement of the air channels can contribute to an optimized flow conduction along the conduction surface.

[0015] The first and / or second conduction surface are flow conducting surfaces, meaning that the first and / or second conduction surface are configured to conduct air flow.

[0016] Those skilled in the art will appreciate that flow grooves exhibit openings along the length of the groove, particularly along its entire length, which is not the case for channels, for example.

[0017] According to some embodiments, for each air flow passage, one or more straight lines may be defined between the flow inlet and the flow outlet, where the angle formed between the or each straight line and the article axis may be 20 degrees or less, preferably less than 10 degrees. The article axis extends between the inlet end and the mouth end configured to receive the air flow, particularly parallel to the opposing sides of the tobacco substrate.

[0018] According to some embodiments, the second conductive surface includes one or several air flow passages formed in recesses on the second conductive surface.

[0019] These features allow several surfaces of the tobacco substrate to be used to form the air flow channels, and therefore the placement of the air flow channels can be further optimized.

[0020] According to some embodiments, the second conductive surface is opposite the first conductive surface.

[0021] These features allow the air channels to be located on either side of a tobacco substrate having, for example, a flat shape. The air channels can be positioned to face each other or to have an offset between them.

[0022] According to some embodiments, the or each air channel is embossed or debossed onto a corresponding surface of the tobacco substrate.

[0023] These features allow the tobacco substrate to be easily manufactured. Furthermore, embossing or debossing the air channels allows for the formation of air channels of complex shapes, such as air channels having variable cross-sectional dimensions and / or shapes along their length. Any suitable manufacturing method that effects embossing or debossing can be used for this purpose. Some of these methods are described below.

[0024] According to some embodiments, it has a flat shape, is made from a tobacco sheet and has a thickness preferably comprised between 0.5 and 5 mm.

[0025] The flat shape of the tobacco substrate is particularly advantageous for its homogeneous heating. For example, a resistive heater can be applied to both sides of the tobacco substrate. Thus, substantially the entire amount of heat generated by the resistive heater can be transferred to the tobacco substrate by conduction and / or convection. Moreover, this shape of the tobacco substrate can be easily manufactured, for example, from a tobacco sheet. Some of these manufacturing methods are described below.

[0026] According to some embodiments, the tobacco substrate comprises tobacco, an aerosol forming agent, and preferably a binder.

[0027] These characteristics make the tobacco substrate suitable for use with an aerosol generating device. In particular, when heated, the aerosol forming agent forms an aerosol, which is released from the flow outlet. Other ingredients, such as flavoring agents, that ensure a particular taste of the inhaled substance can also be used. For example, flavoring agents with polysaccharide carriers, such as those described in EP 2279677, EP 2682007, EP 2682008, EP 2682009, or EP 3533348, can be used.

[0028] According to some embodiments, the tobacco substrate comprises an interior volume that is at least devoid of interior channels having a width and / or depth according to a cross-section of the channels that is substantially equal to or greater than the average width and / or average depth of the flow grooves of the first conductive surface and / or the second conductive surface. In other words, for example, the interior volume of the tobacco substrate may be devoid of large channels, i.e., channels having a macroscopic or large width or depth.

[0029] The interior volume may be defined as the space between the first conductive surface and the second conductive surface. The interior volume is specifically defined by the interior portion of the tobacco substrate that is not visible from the exterior of the tobacco substrate.

[0030] According to some embodiments, the interior volume lacks a channel that forms an air flow path between the flow inlet and a flow outlet opposite the flow inlet.

[0031] The present invention also relates to consumable articles comprising a tobacco substrate as defined below.

[0032] According to different embodiments of the invention, the tobacco substrate may itself form a consumable article that a user can insert into an aerosol generating device to generate an aerosol and remove from the device when used up. In some cases, the tobacco substrate may be wrapped in a wrapper comprising aluminum and / or paper, which allows to preserve the taste of the tobacco substrate and / or to avoid leakage during its use. In some other embodiments, the consumable article may further comprise additional structures, such as for example a filtering / cooling structure. This structure may be attached to the tobacco substrate using the wrapper or any other suitable means. In any case, the filtering / cooling structure and the tobacco substrate may be wrapped in a common wrapper or different wrappers. As in the previous case, the wrapper may comprise aluminum and / or paper.

[0033] The present invention also relates to a manufacturing method for producing a tobacco substrate as defined above, comprising the step of embossing or debossing a tobacco sheet to form air channels.

[0034] These features allow the tobacco substrate to be easily manufactured, for example, using an embossing roller system. The embossing roller system may include an embossing roller that embosses or debosses a predetermined pattern on a tobacco sheet. The tobacco sheet may then be cut to form a plurality of tobacco substrates. The embossing roller may include, for example, a solid surface (such as metal) on which a predetermined pattern is formed using any suitable method (such as cold spray, SLS, 6-axis CNC, etc.). In particular, such methods allow for the formation of thin, complex-shaped protrusions and complex geometric grooves on the surface of the roller. The protrusions and grooves may have irregular, curvilinear shapes that are complementary to the cross-sectional shapes of the air passages that will be formed by these protrusions and grooves.

[0035] Additionally, all tobacco substrates may be formed using the same pattern, in which case the pattern is repeated along the embossing roller, with all tobacco substrates formed by the roller having substantially the same air channel arrangement. This may be used, for example, to obtain a repeatable effect. Alternatively, different patterns may be used to form different arrangements of channels on different tobacco substrates. In this case, the embossing roller may define a unique, e.g., continuous, pattern, with different portions of the unique pattern applied on the different tobacco substrates.

[0036] According to some embodiments, the method includes the step of cutting the embossed or debossed tobacco sheet.

[0037] According to some embodiments, the cutting step is performed simultaneously with the embossing or debossing step or after the embossing or debossing step.

[0038] A special cutting and embossing roller can be used to perform the embossing (or debossing) and cutting steps simultaneously. For example, such a roller can have a first group of projections that cut the tobacco sheet and a second group of projections that embosses or debosses a specific pattern in the tobacco sheet. The first group of projections can penetrate deeper into the tobacco sheet than the second group of projections. To perform continuous embossing / debossing and cutting, an embossing roller with only the second group of projections can be used. The cut can then be performed using any suitable method, such as a cutting wheel, a stationary blade, or a pneumatically operated blade that vibrates a small amount at a high frequency. This allows for a clean cut and reduces the chance of tobacco consumables sticking to the blade. In either case, the cut material can be recovered and reused.

[0039] According to some embodiments, the method further includes the step of extruding the tobacco dough into a tobacco sheet, the extruding step occurring before the embossing or debossing step.

[0040] These characteristics allow a tobacco sheet of desired thickness to be formed from the tobacco dough. This thickness may be comprised, for example, between 0.5 and 5 mm. The tobacco dough used to form the tobacco sheet comprises vaporizable materials, including, for example, tobacco, an aerosol former, and optionally a binder. The tobacco dough may be extruded using any suitable means, such as, for example, a pair of opposing rollers. The dimensions of the tobacco sheet are adapted to the embossing roller system, for example to reduce the amount of unembossed material.

[0041] According to some embodiments, the tobacco sheet is embossed or debossed with a predetermined pattern of optimized air channel placement on the conductive surface of the tobacco substrate.

[0042] These features allow for the same air flow channel configuration to be obtained for all tobacco substrates. Thus, each tobacco substrate can produce substantially the same effect / flavor during a vaping session. Furthermore, a predefined pattern can be developed to obtain an optimized air flow channel configuration for a given size of tobacco substrate. This optimized air flow channel configuration can be determined, for example, using an optimization methodology described in more detail below.

[0043] The present invention also provides a method for optimizing air flow channel configurations on a conduction surface of a tobacco substrate, comprising the steps of: - providing the dimensions and geometry of a tobacco layer and a build volume, the build volume being intended to be adjacent to the tobacco layer within the tobacco substrate, to form said conductive surface and to contain one or several air flow channels; - providing boundary conditions for a build volume; - providing material input data; - determining an internal structure of a build volume by applying a structure construction method within the build volume, taking into account boundary conditions and material input data, the structure construction method being based on an optimization criterion; - using the determined internal structure of the build volume to determine a pattern of optimized air flow channel arrangement on said conductive surface of the tobacco substrate, the pattern including the geometry, shape and number of air flow channels within the build volume; The process and The present invention relates to a method comprising the steps of:

[0044] These features make it possible to determine a pattern that can be used to manufacture a tobacco substrate according to the invention, with an optimized air flow channel arrangement that ensures efficient heating and air flow conduction of the tobacco substrate. The optimized arrangement is determined based on a number of parameters, including the dimensions and geometry of the tobacco layers forming the substrate, boundary conditions, and material input data. The optimization method may be at least partially implemented by a computer software product that includes software instructions for carrying out at least some of the steps of the optimization method. Such a software product may be executed by a computer that includes, inter alia, a processor and a memory. Alternatively, the software product may be executed by several computers connected by a computer network.

[0045] Advantageously, according to the invention, a "building volume" is used as a starting structure from which the optimized topology is created. It is also conceivable that the optimization is not carried out on the tobacco layer, which remains unchanged after carrying out the optimization method. The tobacco layer may for example be in the shape of a flat rectangle with thickness, width and length of 0.1x10x20 mm, and the building volume above this has thickness, width and length of 1x10x20 mm.

[0046] The output data generated by the optimization method includes a pattern, which may represent, for example, a computer-readable file. For example, the pattern may represent a CAD ("Computer Aided Design") file that includes a 3D shape of the pattern. The pattern may then be applied, for example, onto the surface of an embossing roller as described above, in order to emboss / deboss this pattern onto the surface of the tobacco sheet. The patterned surface of the embossing roller may be realized, for example, by 3D printing or any other known technology.

[0047] According to some embodiments, the method further comprises a verification step to verify whether the internal structure of the construction volume satisfies requirements. The requirements may be determined based on one or several optimization criteria and / or boundary conditions. If the requirements are met, the determined pattern is output. If not, the structure construction method may be repeated one or several times, indicating from the construction volume obtained after the previous iteration.

[0048] According to some embodiments, the boundary conditions include at least one of the following elements: - flow rate, - input energy, - Pressure, - Temperature.

[0049] Boundary conditions can be specified before performing the optimization method, and each boundary condition can be formed by a fixed value or a range of values. If a range of values ​​is used, the scope of the optimization method is greatly increased.

[0050] According to some embodiments, the optimization criteria include at least one of the following criteria: - Optimization of pressure drop across the tobacco substrate; - optimizing the temperature of or at the exit end of the tobacco substrate; - Optimizing the tobacco temperature within or on the surface of the tobacco substrate.

[0051] These features make it possible to optimize at least one of the aforementioned factors. For example, optimizing the pressure drop allows optimizing the amount of aerosol delivered to the user in response to the user's puff. Optimizing the temperature of or at the outlet end of the tobacco substrate allows optimizing the temperature of the aerosol delivered to the user. Optimizing the tobacco temperature inside or on the tobacco substrate allows optimizing the temperature of the tobacco substrate to ensure aerosol generation while avoiding its combustion. It is also possible to use multiple optimization criteria to ensure the simultaneous application of at least some of the aforementioned criteria.

[0052] One or several optimization criteria can be implemented using available computer-implemented optimization tools.

[0053] According to some embodiments, the material input data includes general material properties.

[0054] According to some embodiments, the material properties include at least one of the following elements: - Thermal conductivity, - specific heat, - Density.

[0055] According to some embodiments, the material comprises tobacco, preferably consisting essentially of homogenized tobacco material.

[0056] According to some embodiments, the material properties are modeled using at least one of the following material elements: - Moisture in tobacco, - density, - Type of cigarette, - Compression.

[0057] Generally, materials intended to form tobacco substrates have complex compositions, so it may not usually be possible to directly optimize the air flow path arrangement using detailed properties specific to this composition, such as tobacco grain size, moisture, tobacco type, density, composition, etc. Instead, a generalized material may be defined having standard material properties, such as, for example, thermal conductivity, specific heat, and density. The standard material properties may be determined, for example, based on the specific properties mentioned above, before performing the optimization method. For example, thermal conductivity depends on moisture, composition, component density, etc. Specific heat depends on moisture, etc. Density depends on component density, moisture, compaction, etc.

[0058] The invention also relates to concepts and manufacturing methods which include the optimization methods described above and further include manufacturing methods described above, the manufacturing methods being preferably carried out subsequent to the implementation of at least one of the optimization methods.

[0059] The invention and its advantages will be better understood on reading the following description, given by way of non-limiting example only and with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0060] [Figure 1] FIG. 1 is a perspective view of an aerosol generation assembly including an aerosol generation device and a consumable article according to the present invention, the consumable article being usable with the aerosol generation device. [Diagram 2] 2 is a perspective view of the consumable article of FIG. 1, the consumable article including a tobacco substrate according to the present invention. [Diagram 3] FIG. 3 is a top view of the tobacco substrate of FIG. 2. [Figure 4] FIG. 3 illustrates the airflow conductance of the tobacco substrate of FIG. 2. [Diagram 5] FIG. 3 is a schematic diagram of an apparatus suitable for producing the tobacco substrate of FIG. 2. [Figure 6] 3 is a flow chart of an optimization method according to the present invention, which determines the pattern used to manufacture the tobacco substrate of FIG. 2; [Figure 7] FIG. 7 is a schematic diagram showing one of the steps of the optimization method of FIG. 6. [Figure 8] FIG. 7 is a schematic diagram illustrating another step of the optimization method of FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0061] Before the present invention is described, it should be understood that the invention is not limited to the details of construction set forth in the following description, as it will be apparent to one skilled in the art having the benefit of this disclosure that the invention is capable of other embodiments and of being practiced or carried out in various ways.

[0062] As used herein, the term "aerosol generating device" or "device" may include a vaping device that uses a heater element, which will be described in more detail below, to deliver an aerosol, including an aerosol for vaping, to a user. The device may be portable. "Portable" may refer to a device that is held and used by a user. The device may be adapted to generate a variable amount of aerosol (as opposed to a fixed amount of aerosol), for example, by activating the heater element for a variable amount of time, the generation of which may be controlled by a trigger. The trigger may be user-activated, such as a vaping button and / or an inhalation sensor. The inhalation sensor may be sensitive to the inhalation intensity and duration to allow for providing a variable amount of vapor (to mimic the smoking effect of a conventional combustible smoking article, such as a cigarette, cigar, or pipe). The device may include a temperature regulation control to drive the temperature of the heater and / or heated aerosol generating material (aerosol precursor) to a specific target temperature and then maintain the temperature at that target temperature that allows for efficient generation of aerosol.

[0063] The term "aerosol" as used herein may include a suspension of vaporizable material as one or more of solid particles, liquid droplets, and gas. The suspension may be in a gaseous state, including air. Aerosol herein may generally refer to / include a vapor. Aerosol may include one or more components of vaporizable material.

[0064] As used herein, the term "vaporizable material" or "precursor" may refer to a smokable material that may include, for example, nicotine or tobacco and an aerosol-forming agent. Tobacco may take the form of various materials, such as cut tobacco, granulated tobacco, tobacco leaf, and / or reconstituted tobacco. Suitable aerosol-forming agents include polyols (e.g., sorbitol, glycerol, and glycols, such as propylene glycol or triethylene glycol), non-polyols (e.g., monohydric alcohols, acids, such as lactic acid, glycerol derivatives, esters, such as triacetin, triethylene glycol diacetate, triethyl citrate, glycerin, or vegetable glycerin). In some embodiments, the aerosol-generating agent may be glycerol, propylene glycol, or a mixture of glycerol and propylene glycol. The substrate may also include at least one of a gelling agent, a binder, a stabilizer, and a humectant.

[0065] Figure 1 shows an aerosol generation assembly 10 according to the invention, comprising an aerosol generation device 11 and a consumable article 12. The aerosol generation device 11 is intended to operate together with a consumable article 12, which is shown in more detail in Figure 2.

[0066] With reference to FIG. 1, the aerosol generating device 11 comprises a device body 15 extending along a device axis Y. The device body 15 comprises a mouthpiece 16 and a housing 17 arranged successively along the device axis Y. According to the example of FIG. 1, the mouthpiece 16 and the housing 17 form two distinct parts. In particular, according to this example, the mouthpiece 16 is designed to be fixed to or received in an insertion opening formed at one of the ends of the housing 17. In this case, the consumable article 12 can be inserted into the device 11 when the mouthpiece 16 is removed from the housing 17. According to another example (not shown), the mouthpiece 16 and the housing 17 form one unique part. In this case, the consumable article 12 can be inserted into the device 11, for example, through an exit hole. According to both examples, the mouthpiece 16 defines at least partially a through hole adapted to receive the consumable article 12. In particular, the through hole can be adapted to receive at least the oral end of the consumable article 12, which will be explained in more detail below. According to yet another embodiment (not shown), the mouthpiece 16 is not provided on the aerosol generation device 11. In this case, the mouth end of the consumable article 12 may form a mouthpiece designed to contact the lips and / or mouth of the user during a vaping session.

[0067] The housing 17 defines an interior space of the device 11 that accommodates various elements designed to perform different functions of the device 11. This interior space can accommodate, for example, a battery for powering the device 11, a control module for controlling the operation of the device 11, a heating chamber for heating the consumable article 12, etc. In particular, the heating chamber is designed, at least in part, to accommodate at least the tobacco substrate of the consumable article 12 and heat it using a suitable heater. In the example of Fig. 1, the heating chamber can be arranged, for example, in the extension of the through hole of the mouthpiece 16 according to the device axis Y.

[0068] With reference to Fig. 2, the consumable article 12 is, for example, a flat rectangular parallelepiped extending along an article axis X between an inlet end 18 and a mouth end 19 and having external dimensions LxWxH. As will be explained in more detail below, the consumable article 12 is adapted to conduct an air flow from the inlet end 18 to the mouth end 19. In a typical example, the length L of the article 12 along the article axis X is substantially equal to 25-35 mm, for example 33 mm, its width W is comprised between 8-15 mm, for example substantially equal to 12 mm, and its height H is comprised between 0.8-2 mm, for example substantially equal to 1.2 mm. According to different examples, the values ​​L, W and H may be selected, for example, within a range of + / - 40%.

[0069] In the example of FIG. 2, the consumable article 12 is wrapped in a common wrapper 21. In other words, in this example, the wrapper 21 is formed from a unique sheet that wraps substantially the entire length of the consumable article 12 around the article axis X. In other examples, the wrapper 21 extends along only a portion of the length of the consumable article 12. For example, the wrapper 21 can extend along only the tobacco substrate of the consumable article 12, advantageously wrapping only the tobacco substrate. According to another example, the wrapper 21 is formed from two different sheets that, for example, separately wrap the tobacco substrate and the remaining part of the consumable article 12. The wrapper 21 can be made of aluminum and / or paper. In some embodiments, when the wrapper 21 comprises aluminum, the aluminum can wrap only the tobacco substrate to prevent condensation leakage and / or vapor leakage. Furthermore, the aluminum allows better heat transfer. In some embodiments, the consumable article 12 can be provided and used without the wrapper 21.

[0070] The consumable article 12 includes a tobacco substrate 25 for generating an aerosol and a filtering / cooling structure for filtering and / or cooling the aerosol generated by the tobacco substrate 25. The filtering / cooling structure may also function to collect the aerosol flow from the tobacco substrate 25 and guide it to the user's mouth. The filtering / cooling structure may be completely hollow or may include flow guides and / or filtering elements. The filtering / cooling structure may be disposed in the extension of the tobacco substrate 25 according to the article axis X. Thus, the tobacco substrate 25 is, for example, adjacent to the inlet end 18 of the consumable article 12, and the filtering / cooling structure is adjacent to the mouth end 19 of the consumable article 12. In some embodiments, no filtering / cooling structure is provided. In this case, the tobacco substrate 25 extends between the inlet end 18 and the mouth end 19.

[0071] As shown in FIG. 3, the tobacco substrate 25 defines the inlet end 18 of the consumable article 12 and extends to an outlet end 29 according to the article axis X. According to different embodiments, the outlet end 29 may be adjacent to a filtering / cooling structure or may form the mouth end 19 of the consumable article 12. Its axial extension length L1 is less than or equal to the length L of the consumable article 12. For example, L1 may be substantially equal to ½L. The tobacco substrate 25 includes a vaporizable material as defined above. The vaporizable material may, for example, be compressed to form a solid structure capable of releasing an aerosol upon heating.

[0072] As a consumable article 12, the tobacco substrate 25 defines, for example, a substantially flat rectangular parallelepiped defining a pair of opposing side surfaces 33A, 33B (shown as the upper and lower left sides of the substrate in FIG. 4) and a pair of opposing conductive surfaces 34A, 34B (only conductive surface 34A is visible in FIG. 4), each said surface extending along an article axis X. The pair of opposing conductive surfaces 34A, 34B is, for example, at least 5 times, advantageously 10 times, wider than the pair of side surfaces 33A, 33B. The pair of opposing conductive surfaces 34A, 34B in particular extends according to a direction perpendicular to the direction in which the side surfaces 33A, 33B extend.

[0073] The conductive surfaces 34A, 34B form the exterior surfaces of the tobacco substrate 25. In particular, the conductive surfaces 34A, 34B forming the exterior surfaces are visible from the outside of the tobacco substrate 25. In other words, if the tobacco substrate 25 defines a substantially planar rectangular parallelepiped, the conductive surfaces 34A, 34B form the exterior surfaces of this rectangular parallelepiped. In particular, the conductive surfaces 34A, 34B are not located in an internal cavity, for example, within the rectangular parallelepiped.

[0074] The conductive sides 34A, 34B are designed to be heated by conduction and / or convection by the heating chamber of the device 11. According to another embodiment, the tobacco substrate 25 includes a susceptor and is further designed to be inductively heated by magnetic interaction between the susceptor and a magnetic coil. Each side 33A, 33B may define a generally flat surface that may define rounded edges on each cross section.

[0075] At least one, and advantageously each, of the conduction surfaces 34A, 34B of the tobacco substrate 25 defines one or more air flow passages between the inlet end 18 and the outlet end 29 that are designed to conduct air flow along the corresponding conduction surface 34A, 34B.

[0076] The first and / or second conduction surfaces 34A, 34B are flow conduction surfaces. By "flow conduction surface" it is understood that the corresponding conduction surface is configured to conduct or guide or direct the air flow in an air flow path defined by that surface, in particular between the inlet end 18 and the outlet end 29.

[0077] Each air flow passage can extend generally along the article axis X, meaning that the air flow conducted by this air flow passage is mainly guided from the inlet end 18 to the outlet end 29. In particular, the air flow conducted by the corresponding air flow passage can extend substantially along the article axis X over at least 80% of the length of the air flow passage defined along the direction of the air flow conducted by this air flow passage or defined by the walls of the air flow passage. In this case, an "air flow passage extending substantially along the article axis X" can be preferably understood as an air flow passage extending along a direction parallel to the article axis X with a variation angle of 20 degrees or less. The variation angle is defined between the direction in which the air flow passage extends and the article axis X. If the air flow passage extends strictly along the article axis X, the variation angle is equal to zero.

[0078] At least some of the air flow passages may be straight and / or at least some of the air flow passages may be curvilinear. Each air flow passage includes a flow inlet disposed at the inlet end 18 of the tobacco substrate 25, a flow outlet disposed at the outlet end 29 of the tobacco substrate 25, and a flow groove extending along a corresponding conduction surface 34A, 34B between the flow inlet and the flow outlet.

[0079] In the following, examples of the arrangement of the air flow passages extending generally along the article axis X will be described.

[0080] Preferably, for each air flow passage, a straight line may be defined between a flow inlet located at the inlet end 18 and a flow outlet located at the outlet end 29 of the tobacco substrate 25, in which case the angle formed between this line and the article axis X may be no greater than 20 degrees, preferably less than 10 degrees.

[0081] The transverse distance between the flow inlet and the flow outlet may be defined along a transverse direction perpendicular to the article axis X. The transverse direction in particular extends parallel to the width W of the consumable article 12. The transverse distance between the flow inlet and the flow outlet may be, for example, one third, preferably one quarter, of the overall width of the tobacco substrate 25. The overall width of the tobacco substrate 25 may be defined along the transverse direction, i.e., with reference to FIG. 3, for example, perpendicular to the length L1 of the tobacco substrate 25.

[0082] At least some of the air passages may exhibit variable cross-sectional dimensions and / or shapes along their length. In particular, the width and / or depth of the flow grooves of these air passages may vary along their length. The cross-sectional shapes of the grooves may also vary. For example, in some cross-sections, the grooves may have a rounded shape and in some other cross-sections, a rectangular shape. The change in shape and / or size may be smooth (gradual) or discontinuous.

[0083] Furthermore, at least some of the air flow paths may include multiple flow outlets and / or multiple flow inlets. Furthermore, at least two air flow paths may share at least one common flow inlet and / or at least one common flow outlet and / or at least a common portion of a corresponding flow groove. In particular, at least two air flow paths at the inlet end 18 may merge into a single air flow path at the outlet end 29. Conversely, at least one air flow path at the inlet end 18 may split into two separate air flow paths at the outlet end 29. In the example of FIG. 3, the air flow path 41 includes a single flow inlet 42 and two flow outlets 43A, 43B. Conversely, the air flow path 51 includes two flow inlets 52A, 52B and a single flow outlet 53.

[0084] As shown in FIG. 4, in operation, airflow may first be conducted from the device inlet to the outside of the tobacco substrate 25 along the sides 33A, 33B of the tobacco substrate 25 to the inlet end 18 of the tobacco substrate 25. To this end, the heating chamber of the device 11 may have a cup shape that defines an airflow channel between its sidewalls and the sides 33A, 33B of the tobacco substrate 25. Thus, the airflow enters the tobacco substrate through the flow inlets of the airflow channels formed in each or at least one of the conduction surfaces 34A, 34B of the tobacco substrate 25. The airflow is then conducted by the airflow channels to the corresponding flow outlets at the outlet end 29 of the tobacco substrate 25. Finally, the airflow is delivered to the user from the mouth end 19 of the consumable article 12 or through the mouthpiece 16 of the device 11.

[0085] A variety of manufacturing equipment can be used to produce the tobacco substrate 25 according to the present invention.

[0086] An example of such a manufacturing facility 100 is shown in FIG. 5. Referring to this FIG. 5, the manufacturing facility 100 includes a receiving mechanism 105, a pre-roll system 110, an embossing roller system 120, and a delivery mechanism 130. The receiving mechanism 105 can receive a vaporizable material intended to form a tobacco substrate 25, for example in the form of a tobacco dough. The pre-roll system 110 can pre-roll the tobacco dough with rollers to form a flat sheet. For this purpose, the pre-roll system 110 includes, for example, a pair of rollers connected to the receiving mechanism 105. The embossing roller system 120 includes, for example, an embossing roller 122 and a guide roller 124. The embossing roller 122 is configured to emboss or deboss a predetermined pattern on the tobacco sheet to form at least one tobacco substrate 25 including one or several air channels, as explained above. Advantageously, the embossing roller 122 is configured to emboss / deboss a plurality of predetermined patterns on the tobacco sheet to form a plurality of tobacco substrates 25. These patterns can be the same or different. In this latter case, different air flow channel arrangements can be obtained on the different tobacco substrates 25. The embossing roller 122 can, for example, comprise a solid surface (such as metal) on which a predetermined pattern is formed using any suitable method (such as cold spray, SLS, 6-axis CNC, etc.). In an embodiment in which both conductive surfaces 34A, 34B of the tobacco substrate 25 define air flow channels, two embossing rollers 122 facing each other can be used. In some embodiments, the embossing roller 122 can also perform cutting of the tobacco sheet to form a plurality of tobacco substrates 25. In some other embodiments, a special cutting mechanism is arranged between the embossing roller system 120 and the delivery mechanism 130. The delivery mechanism 130 is configured to deliver the tobacco substrate 25 formed after cutting. In some cases, the delivery mechanism 130 may also be configured to form a wrapper around these substrates 25 and / or assemble these substrates 25 with a filtering / cooling structure.

[0087] The tobacco dough may be a substrate comprising tobacco particles and / or at least one stimulant, such as nicotine and / or flavor, an aerosol-forming agent, and an inhalable agent, including a gelling agent or binder. The aerosol-forming agent may represent 20-70% by weight, based on the dry weight of the substrate. The gelling agent may represent 1-8% by weight, based on the dry weight. The gelling agent may be guar gum, gellan gum, non-proteinaceous polysaccharides, and mixtures thereof. The substrate may further comprise an antidegradant and / or a thickening stabilizer, such as carboxymethylcellulose. Examples of tobacco substrates to be pressed are described in WO2021094365. The mixture may comprise solid tobacco ground to a particle size (D90) of 300 microns or less, preferably 20-220 microns. The tobacco particles may be mixed with the aerosol-forming agent, the gelling agent, optionally a stabilizer and water. A tobacco dough with a liquid content of about 30-50% can be obtained. The production of the tobacco dough may be carried out as described in EP 3852554.

[0088] The method of manufacturing the tobacco substrate 25 may be performed, for example, by the manufacturing facility 100 of FIG. 5. The method includes an initial step of extruding tobacco dough into a tobacco sheet. This step may be performed by a pre-roll system 110. The method then includes a step of embossing / debossing the tobacco sheet with a plurality of patterns corresponding to the air channel arrangements intended to be formed in the tobacco substrate 25. This step is performed by an embossing roller system 120. The method then includes a step of cutting the embossed tobacco sheet to form a plurality of tobacco substrates 25. This step may be performed by the embossing roller system 120 simultaneously with the embossing / debossing step, or by a separate cutting mechanism after the embossing / debossing step. Finally, the tobacco substrate 25 is delivered by a delivery mechanism 130 and wrapped and / or assembled with a filtration / cooling structure, for example, as described above.

[0089] The predetermined pattern used to create one or more air flow channels on a tobacco substrate 25 according to the present invention may be determined using an optimization method 200 performed prior to the manufacturing method. In particular, the optimization method determines an optimized air flow channel arrangement on at least one conduction surface of the tobacco substrate 25 by modeling the airflow behavior around and within the tobacco substrate 25.

[0090] The optimization method may be at least partly implemented by a computer software product comprising software instructions for performing at least some of the steps of the optimization method. Such a software product may be executed by a computer including, inter alia, a processor and a memory. Alternatively, the software product may be executed by several computers linked by a computer network. The optimization method 200 will now be described in detail with reference to Figures 6 to 8.

[0091] Referring to FIG. 6, which shows a flow chart of an optimization method 200, the optimization method 200 includes initial steps 210-230 of providing input data.

[0092] In particular, during step 210, the dimensions and the geometry of the tobacco layer and the build volume are provided. The tobacco layer models a layer of the tobacco substrate 25 that is not intended to include air channels. In other words, the tobacco layer remains unchanged after carrying out the optimization method 200. An example of a tobacco layer 310 is shown in FIG. 7. According to this example, the tobacco layer 310 has a rectangular shape extending along the article axis X. The tobacco layer 310 may for example have a thickness, width and length of 0.1x10x20 mm. The build volume is a volume adjacent to one side of the tobacco layer and is intended to model a layer of the tobacco substrate 25 that includes one or several air channels. The build volume is therefore used as a starting structure from which the optimized topology is created. Initially, the build volume is assumed to be, for example, empty. Furthermore, it is also possible to specify which side of the build volume is considered to be the inflow end of the tobacco substrate 25 and which side of the build volume is considered to be the outflow end of the tobacco substrate 25. According to the example of FIG. 7, as the tobacco layer 310, the build volume 320 has a rectangular shape with thickness, width and length of, for example, 1x10x20 mm. This build volume 320 includes a side 321 considered as the inflow end of the tobacco substrate 25 and a side 322 considered as the outflow end. Furthermore, according to the example of FIG. 7, only one build volume 320 is defined, which is located on one side of the tobacco layer 310. In this case, the modeled tobacco substrate 25 includes only one conductive surface, which includes one or several air flow paths. In the general case, it is possible to define two build volumes, which are located on both sides of the tobacco layer. Alternatively, it is possible to model only half of the tobacco substrate 25 with one build volume. The whole tobacco substrate 25 can be modeled by a symmetric reflection of the modeled half.

[0093] During step 220, boundary conditions for the build volume are provided. The boundary conditions may include at least one of the following elements, preferably a combination of at least two or three of the following elements: - flow rate, - input energy, - Pressure, - Temperature.

[0094] Each boundary condition may be formed by a fixed value or a range of values. Advantageously, boundary conditions may be defined only on the sides of the build volume that are intended to model the inlet and outlet ends of the tobacco substrate 25. Thus, in the example of Figure 7, boundary conditions may be defined only on sides 321 and 322 of the build volume.

[0095] During step 230, material input data is provided. This material input data corresponds to the physical properties of the material intended to form the tobacco substrate 25. In particular, this material may correspond to a vaporizable material, and the input data may correspond to the physical properties of this vaporizable material, such as, for example, tobacco particle size, moisture, tobacco type, density, composition, etc. Alternatively, the material intended to form the tobacco substrate 25 is modeled by a generalized material having standard material properties, such as, for example, thermal conductivity, specific heat, and density. In this case, the standard material properties may be obtained experimentally, for example, by observing the behavior of the vaporizable material.

[0096] During step 240, the internal structure of the build volume is determined by applying a structure build method within this build volume. This internal structure respects the boundary conditions and the material input data. The structure build method can be performed by any commercially available CFD ("Computational Fluid Dynamics") solver equipped with a topology optimization tool. This topology optimization tool includes optimization criteria selected based on the parameters of the modeled tobacco substrate 25 to be optimized. For example, the optimization criteria include at least one of the following criteria: - Optimization of pressure drop across the tobacco substrate 25; - optimizing the temperature of or at the exit end 19 of the tobacco substrate 25; - Optimizing the tobacco temperature within or on the tobacco substrate 25.

[0097] For example, optimizing the pressure drop allows optimizing the amount of aerosol delivered to the user in response to the user's puff. Optimizing the temperature of the outlet end 19 of the tobacco substrate 25 allows optimizing the temperature of the aerosol delivered to the user. Optimizing the tobacco temperature within or on the surface of the tobacco substrate 25 allows optimizing the temperature of the tobacco substrate 25 to ensure aerosol generation while avoiding its combustion. It is also possible to use multiple optimization criteria to ensure the simultaneous application of at least some of the aforementioned criteria.

[0098] The geometry, shape, and number of air channels in the optimized build volume are then determined. For example, as described above, at least some of the air channels can have widths and / or depths that vary along their lengths.

[0099] 8 shows an internal structure of the build volume 320 that has been further determined during step 240, for example by applying one iteration of one of the optimization criteria. Such an internal structure may thus include four walls extending along the article axis X and defining five air channels. This internal structure may be further optimized by applying further iterations of one or several optimization criteria, as described below.

[0100] During step 250, it is verified whether the obtained structure of the optimized build volume meets the above-mentioned requirements. In particular, in this step, the boundary conditions defined in step 220 may be verified. Additionally or alternatively, it may be verified whether one or several optimization criteria with corresponding requirements have been achieved. For example, for the pressure drop optimization criterion, it may be verified whether the pressure drop is less than a predefined threshold value. Similarly, for example, for the tobacco temperature optimization criterion, it may be verified whether this temperature is within a predefined range.

[0101] If the requirements are met, the next step 260 is performed, otherwise another iteration of step 240 is performed, starting from the optimized built volume obtained after the previous iteration of step 250.

[0102] During step 260, a pattern of optimized air channel arrangement on the conductive surface of the modeled tobacco substrate 25 is output. The pattern includes the determined geometry, shape and number of air channels in the build volume. The pattern can represent, for example, a computer-readable file. For example, the pattern can represent a CAD ("Computer Aided Design") file that includes the 3D shape of the pattern. Advantageously, the pattern file can be read and used to execute the corresponding structure by a 3D printer. Alternatively, the pattern file can be used to execute a molding process (e.g. computer numerically controlled injection molding) or laser engraving.

Claims

1. A tobacco substrate (25) for use in an aerosol generating device (11), comprising a first flow conducting surface (34A), the first flow conducting surface (34A) including air flow paths (41, 51) formed in recesses on the first flow conducting surface (34A), the air flow paths (41, 51) including a flow inlet (42, 52A, 52B), a flow outlet (43A, 43B, 53), and a flow groove extending along the first flow conducting surface (34A) between the flow inlet (42, 52A, 52B) and the flow outlet (43A, 43B, 53), wherein the width and / or depth and / or cross-sectional shape of the flow groove varies along the length of the flow groove, a tobacco substrate (25).

2. The tobacco substrate (25) according to claim 1, wherein the first flow conducting surface (34A) includes a plurality of air flow paths (41, 51).

3. The tobacco substrate (25) according to claim 1, wherein at least one or each of the air flow paths (41, 51) includes a plurality of flow outlets (43A, 43B) and / or a plurality of flow inlets (52A, 52B).

4. The tobacco substrate (25) according to claim 1, further comprising a second flow conducting surface (34B) including one or several air flow paths (41, 51) formed in a recess on the second flow conducting surface (34B).

5. The tobacco substrate (25) according to claim 4, wherein the second flow conducting surface (34B) is on the opposite side of the first flow conducting surface (34A).

6. The tobacco substrate (25) according to claim 1, wherein the or each air flow path (41, 51) is embossed or debossed on the corresponding surface (34A, 34B) of the tobacco substrate (25).

7. The tobacco substrate (25) according to claim 1, having a flat shape, formed from a tobacco sheet, and preferably having a thickness included in the range of 0.5 to 5 mm.

8. The tobacco substrate (25) according to claim 1, comprising tobacco, an aerosol forming agent, and preferably a binder.

9. A consumable article (12) comprising the tobacco substrate (25) according to any one of claims 1 to 8.

10. A manufacturing method for manufacturing the tobacco substrate (25) according to any one of claims 1 to 8, the manufacturing method including a step of embossing or debossing a tobacco sheet to form an air flow path.

11. The manufacturing method according to claim 10, further comprising the step of cutting the embossed or debossed tobacco sheet.

12. The step of cutting is performed simultaneously with the step of embossing or debossing, or after the step of embossing or debossing, according to the manufacturing method of claim 11.

13. The manufacturing method according to claim 10, further comprising the step of extruding tobacco base material into a tobacco sheet, and the step of extruding is performed before the step of embossing or debossing.

14. The tobacco sheet is embossed or debossed using a predetermined pattern of an optimized air flow path arrangement on the flow conduction surfaces (34A, 34B) of the tobacco base material (25), according to the manufacturing method of claim 10.

15. An optimization method (200) for an air flow path arrangement on the flow conduction surfaces (34A, 34B) of a tobacco base material (25), comprising: - A step (210) of providing dimensions and geometric shapes of a tobacco layer (310) and a construction volume (320) that model a layer of the tobacco base material (25) including one or several air flow paths (41, 51), wherein the construction volume (320) is adjacent to the tobacco layer (310) within the tobacco base material (25) and forms the flow conduction surface, the step (210); - A step (220) of providing boundary conditions for the construction volume (320); - A step (230) of providing material input data; - A step (240) of determining the internal structure of the construction volume (320) by applying a structural construction method within the construction volume (320) while considering the boundary conditions and the material input data, wherein the structural construction method is based on optimization criteria, the step (240); - A step (260) of determining a pattern of an optimized air flow path arrangement on the flow conduction surfaces (34A, 34B) of the tobacco base material (25) using the determined internal structure of the construction volume (320), wherein the pattern includes the geometric shape, shape, and number of air flow paths within the construction volume (320), the step (260); The method (200) comprising the above steps.

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