EP4651744A1

EP4651744A1 - Aerosol generating device comprising two heating plates

Info

Publication number: EP4651744A1
Application number: EP24700326.2A
Authority: EP
Inventors: Alec WRIGHT; Jaakko MCEVOY
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2023-01-19
Filing date: 2024-01-17
Publication date: 2025-11-26
Also published as: KR20250131815A; JP2026501819A; WO2024153673A1

Abstract

The invention relates to an aerosol generating device configured to operate with a flat-shaped tobacco article (12) and comprising a flat-shaped heating chamber (50) extending along a device longitudinal axis (X'). The heating chamber (50) is configured to receive at least a tobacco portion (15) of the flat-shaped tobacco article (12) and comprises a first heating surface (72A) and a second heating surface (72B) configured to be in contact respectfully with a first external surface and a second external surface of the tobacco portion (15); The first and the second heating surfaces (72A, 72B) are arranged opposite to each other according to an elevation axis (Z) perpendicular to each of the heating surfaces (72A, 72B) and are in offset relative to each other according to an offset axis perpendicular to the elevation axis (Z).

Description

Aerosol generating device comprising two heating plates

FIELD OF THE INVENTION

The present invention concerns an aerosol generating device comprising two heating plates.

Particularly, the aerosol generating device according to the invention is configured to operate with a tobacco article, for example a flat-shaped tobacco article, which comprises for example a solid substrate able to form aerosol when being heated. Thus, such type of aerosol generating devices, also known as heat-not-burn devices, is adapted to heat, rather than burn, the substrate by conduction, convection and/or radiation, to generate aerosol for inhalation.

BACKGROUND OF THE INVENTION

The popularity and use of reduced-risk or modified-risk devices (also known as vaporisers) has grown rapidly in the past few years as an aid to assist habitual smokers wishing to quit smoking traditional tobacco products such as cigarettes, cigars, cigarillos, and rolling tobacco. Various devices and systems are available that heat or warm vaporizable substances as opposed to burning tobacco in conventional tobacco products.

A commonly available reduced-risk or modified-risk device is the heated substrate aerosol generation device or heat-not-burn device. Devices of this type generate aerosol or vapour by heating an aerosol substrate that typically comprises moist leaf tobacco or other suitable vaporizable material to a temperature typically in the range 150°C to 350°C. Heating an aerosol substrate, but not combusting or burning it, releases aerosol that comprises the components sought by the user but not the toxic and carcinogenic byproducts of combustion and burning. Furthermore, the aerosol produced by heating the tobacco or other vaporizable material does not typically comprise the burnt or bitter taste resulting from combustion and burning that can be unpleasant for the user and so the substrate does not therefore require the sugars and other additives that are typically added to such materials to make the smoke and/or vapour more palatable for the user. An aerosol generating device generally encloses at least one heating plate intended to heat the aerosol substrate. During operation, a heat transfer occurs between the heating plate and the aerosol substrate. However, heating plates come with a downside of consuming a lot of energy to be brought up to a predefined temperature and thus to heat the tobacco article to the target temperature. Hence, autonomy of the aerosol generating device is limited and a user needs to reload or to replace the power batteries of the device often.

SUMMARY OF THE INVENTION

One of the aims of the invention is therefore to provide an aerosol generating device requiring less energy to heat and evaporate the vaporizable material from a tobacco article.

For this purpose, the invention relates to an aerosol generating device configured to operate with a flat-shaped tobacco article and comprising a flat-shaped heating chamber extending along a device longitudinal axis, the flat-shaped tobacco article extending along an article longitudinal axis, and comprising a tobacco portion and a non-tobacco portion arranged successively along the article longitudinal axis, the tobacco portion defining a first external surface and a second external surface opposite to the first external surface ; the heating chamber being configured to receive at least the tobacco portion of the flat-shaped tobacco article, and comprising a first heating surface and a second heating surface ; configured to be in contact respectfully with the first external surface and the second external surface of the tobacco portion ; wherein the first and the second heating surfaces are arranged opposite to each other according to an elevation axis perpendicular to each of the heating surfaces, said first and second heating surface being in offset relative to each other according to an offset axis perpendicular to the elevation axis.

Thanks to these features, it is possible to better control the heating of the tobacco portion carried out by the heating surfaces. It is notably possible to create different heating areas in the tobacco portion, depending on their positions relative to the heating surfaces, in order to optimize the heating of the tobacco portion.

The temperature at which each heating surface is heated can be adjusted depending of the position of the heating surface relative to the tobacco portion. For example, a heating surface facing an abutting part of the tobacco portion may be heated at a lower temperature than a heating surface closer to the mouthpiece, reducing vapour formed at the bottom end of the chamber that would otherwise leak, condensate and then require cleaning by the user.

Optional features will now be set out. These are applicable singly or in any combination with any aspect.

According to some embodiments, the area of each heating surface is smaller than the area of the corresponding external surface of the tobacco portion.

The inventors found that, surprisingly, the heating surfaces in contact with the external surfaces of the tobacco portion could be smaller than said external surfaces, while still providing sufficient heating to evaporate the vaporizable material.

Thanks to these features, it is possible to provide an aerosol generating device requiring less energy to heat and evaporate the vaporizable material from a tobacco article, while still heating the tobacco article in an optimal way. Particularly, thanks to their smaller size, the heating surfaces enable to rapidly heat the tobacco article to a predetermined temperature and to maintain its temperature close to this predetermined temperature with little energy, as compared to larger heating surfaces.

A combination of two heating surfaces smaller than the external surface of the tobacco portion thus enables to optimize the heating of the tobacco article.

According to some embodiments, the first and the second heating surfaces are arranged to form in a central plane arranged between the heating surfaces at least one first zone corresponding to an overlapping zone of orthogonal projections of the heating surfaces in the central plane; and at least one second zone corresponding to a nonoverlapping zone of said orthogonal projections. The tobacco portion extending in the or each first zone is thus heated from both sides, allowing a higher thermal penetration into the tobacco article, which enables to rapidly generate vapour with little energy, allowing a fast puff by a user.

The tobacco portion extending in the or each second zone is heated from only one side. Vapour is thus generated after a longer time than in the first zone.

The different zones allow having different heating profiles in the tobacco portion, allowing vapour formation to be more spread out in time during the whole vaping session. Thus, the user experience while using the aerosol generating device can be improved.

According to some embodiments, at least one first zone is comprised between two second zones.

According to some embodiments, said first zone extends between two said second zones along the device longitudinal axis and/or along a device transversal axis perpendicular to the device longitudinal axis.

Thanks to these features, it is possible to create low-heated zones, in which the tobacco portion is heated at a lower temperature. For example, the heating surfaces may be arranged so that an abutting part of the tobacco portion may be in the second zone of the central plane. Said part is thus only in contact with one heating surface and may thus be heated at a lower temperature than if it was heated from both sides. This reduces vapour formed at the bottom end of the chamber that would otherwise leak, condensate and then require cleaning by the user.

According to some embodiments, the first and the second heating surfaces are arranged to further form in the central plane at least one third zone corresponding to a nonoverlapping zone of an orthogonal projection of the tobacco portion with said projections of the heating surfaces.

The tobacco portion extending in said third zone is thus heated only via conduction within the tobacco portion and generates vapour after a longer time than in the second zone. It is particularly advantageous to arrange the heating surfaces so that that the abutting part of the tobacco portion is in said third zone of the central plane. According to some embodiments, the third zone is formed at a periphery of said orthogonal projection of the tobacco portion.

According to some embodiments, the third zone forms a corner of said orthogonal projection of the tobacco portion.

According to some embodiments, the third zone surrounds at least partially said first and second zones.

Depending on the tobacco article, the heating surfaces and the target temperatures, several arrangements can be chosen, in order to provide optimized heating and vapour delivery.

According to some embodiments, the first and the second heating surfaces are operated at different target temperatures.

Thanks to these features, it is possible to control the heating of the tobacco portion carried out by the heating surfaces using different heating profiles. Each heating profile can be chosen for example based on the nature of the heating surface. Thus, the heating of the tobacco portion can be optimized according to the different heating surfaces.

The temperature at which each surface is heated can also be adjusted depending of the position of the heating surface relative to the tobacco portion. For example, a heating surface facing an abutting part of the tobacco portion may be heated at a lower temperature than a heating surface closer to the mouthpiece, reducing vapour formed at the bottom end of the chamber that would otherwise leak, condensate and then require cleaning by the user.

According to some embodiments, at least one second zone is designed to be adjacent to an orthogonal projection of the non-tobacco portion in the central plane; and the heating surface forming said second zone is operated at a higher target temperature than the other heating surface.

The non-tobacco portion acts as a cooling element, so it is possible to operate the heating surface forming said second zone without leakage issue. It allows fast delivery of vapour, while enabling to heat the abutting part of the tobacco portion at a lower temperature to reduce the risks of forming vapour at the bottom end of the chamber.

According to some embodiments, the heating chamber comprises a first plate and a second heating plate forming partially opposite walls of the heating chamber, and comprising respectively the first and second heating surfaces.

Each heating plate includes a planar substrate and a resistive heating track embedded in or mounted on the planar substrate.

According to some embodiments the planar substrate of each heating plate comprises a rigid material. The rigid material is preferably chosen between ceramics and metal.

Metal and ceramics present both good physical properties to ensure the operation of the aerosol generating device according to the invention. For example, it is known that ceramics presents a greater value of heat capacity than metal. Metal heating plates can be heated more rapidly whereas ceramics heating plates can store more thermal energy and heat more homogeneously the tobacco portion.

The heating plates may be made of the same material or of different materials, depending of the thermal properties required.

Each heating plate can present a homogeneous body made from a same material, like as metal or ceramics.

For example, at least one heating plate may be made of oxide ceramic material, such as AI2O3, zirconia, silicon nitride or aluminum nitride.

In a variant, the planar substrate of each heating plate comprises a flexible, heat- resistant resin. The resin is preferably chosen between polyimide and fluororesin.

In a variant, the heating chamber comprises a long strip of flexible heater comprising two separate track patterns and wound around the heating chamber so those two patterns form the first and second heating surfaces respectively. According to some embodiments, each heating surface is continuous.

In other words, each plate is made in one piece, providing a continuous heating surface. It allows a more homogeneous heating of the external surfaces of the tobacco portion, compared to a heating plate made of a plurality of heating elements.

According to some embodiments, each heating surface is flat.

The flat surfaces allows a more homogeneous heating of the tobacco article, whose external surfaces are thus in contact with the heating plates.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its advantages will be better understood upon reading the following description, which is given solely by way of non-limiting example and which is made with reference to the appended drawings, in which:

- Figure 1 is a perspective view of an aerosol generating assembly, the aerosol generating assembly comprising an aerosol generating device according to the invention and a tobacco article usable with the aerosol generating device;

- Figure 2 is a perspective view of the tobacco article of Figure 1 ;

- Figure 3 is a partial cross-sectional view of the aerosol generating assembly of Figure 1 according to plane III;

- Figure 4 is a partial perspective view of the aerosol generating assembly of Figure 1 , in which only the tobacco article and the heating plates of the aerosol generating device has been represented ;

- Figure 5 is a schematic above representation of orthogonal projections in a central plane of the heating plates and tobacco article of Figure 4;

- Figure 6 is a view similar to Figure 5, the tobacco article and the heating plates being arranged according to a second embodiment; - Figure 7 is a view similar to Figure 5, the tobacco article and the heating plates being arranged according to a third embodiment;

- Figure 8 is a view similar to Figure 7, the tobacco article and the heating plates being arranged according to a variant of the third embodiment;

Before describing the invention, it is to be understood that it is not limited to the details of construction set forth in the following description. It will be apparent to those skilled in the art having the benefit of the present disclosure that the invention is capable of other embodiments and of being practiced or being carried out in various ways.

The expression “substantially equal to” is understood hereinafter as an equality at plus or minus 10% and preferably at plus or minus 5%.

As used herein, the term “aerosol generating device” or “device” may include a vaping device to deliver an aerosol to a user, including an aerosol for vaping, by means of a heater element explained in further detail below. The device may be portable. “Portable” may refer to the device being for use when held by a user. The device may be adapted to generate a variable amount of aerosol, e.g. by activating the heater element for a variable amount of time (as opposed to a metered dose of aerosol), which can be controlled by a trigger. The trigger may be user activated, such as a vaping button and/or inhalation sensor. The inhalation sensor may be sensitive to the strength of inhalation as well as the duration of inhalation to enable a variable amount of vapour to be provided (so as to mimic the effect of smoking a conventional combustible smoking article such as a cigarette, cigar or pipe, etc.). The device may include a temperature regulation control to drive the temperature of the heater and/or the heated aerosol generating substance (aerosol pre-cursor) to a specified target temperature and thereafter to maintain the temperature at the target temperature that enables efficient generation of aerosol.

As used herein, the term “aerosol” may include a suspension of vaporizable material as one or more of: solid particles; liquid droplets; gas. Said suspension may be in a gas including air. Aerosol herein may generally refer to/include a vapour. Aerosol may include one or more components of the vaporizable material. As used herein, the term “vaporizable material” or “precursor” may refer to a smokable material which may for example comprise nicotine or tobacco and an aerosol former. Tobacco may take the form of various materials such as shredded tobacco, granulated tobacco, tobacco leaf and/or reconstituted tobacco. Suitable aerosol formers include: a polyol such as sorbitol, glycerol, and glycols like propylene glycol or triethylene glycol; a non-polyol such as 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 comprise at least one of a gelling agent, a binding agent, a stabilizing agent, and a humectant.

DESCRIPTION OF A FIRST EMBODIMENT OF THE INVENTION

Figure 1 shows an aerosol generating assembly 10 comprising an aerosol generating device 1 1 and a tobacco article 12. The aerosol generating device 11 is intended to operate with the tobacco article 12 which is shown in more detail in Figure 2.

In the example of this Figure 2, the tobacco article 12 is a flat-shaped tobacco article presenting for example a flat-shaped cuboid extending along an article longitudinal axis X and an article transversal axis Y and having external dimensions L12xW12xD12. In a typical example, the length L12 of the article 12 according to the article longitudinal axis X equals substantially to 33 mm while its width W12 and depth D12 are substantially equal respectively to 12 mm and 1 ,2 mm. According to different examples, the values L12, W12 and D12 can be selected within a range of +/- 40%, for example. The depth D12 of the tobacco article 12 is formed by a pair of parallel walls 13A, 13B, called hereinafter narrow walls 13A, 13B, and the width W12 of the tobacco article 12 is formed by a pair of parallel walls 14A, 14B, called hereinafter wide walls 14A, 14B. In some embodiments, the edges between the wide and narrow walls 13A, 13B, 14A, 14B can be rounded. According to other embodiments of the invention, the tobacco article 12 can have any other suitable flat shape and/or external dimensions. According to still other embodiments, the tobacco article 12 can present any other suitable shape, as for example a stick shape. According to some embodiments, the wide walls 14A, 14B may present corrugations, as shown in Figure 4. The tobacco article 12 comprises a tobacco portion 15 and a non-tobacco portion 16, also called mouthpiece portion 16, arranged along the article longitudinal axis X. The tobacco portion 15 may for example be slightly longer than the non-tobacco portion 16. The tobacco portion 15 is formed by parallel walls 15A, 15B which are parts of the wide walls 14A, 14B of the tobacco article 12. For example, the length L15 of the tobacco portion 15 according to the article longitudinal axis X may be substantially equal to 18 mm. The width W15 of the tobacco portion 15 is equal to the width W12 of the tobacco article 12. The length L16 of the mouthpiece portion 16 according to the article longitudinal axis X may be substantially equal to 15 mm. The tobacco portion 15 defines an abutting end 18 of the article 12 and the non-tobacco portion 16 defines a mouth end 20 of the article 12. The tobacco portion 15 and the non-tobacco portion 16 may be fixed one to the other by a wrapper 21 extending around the article longitudinal axis X. The wrapper 21 forms the narrow and wide walls 13A, 13B, 14A, 14B of the tobacco article 12. In some embodiments, the wrapper 21 is formed from a same wrapping sheet. In some other embodiments, the wrapper 21 is formed by separate wrapping sheets wrapping separately the portions 15, 16 and fixed one to the other by any other suitable mean. The wrapper 21 may, for example, comprise paper and/or non-woven fabric and/or aluminium foil. The wrapper 21 may be porous or air impermeable and forms a plurality of airflow channels extending inside the article 12 between the abutting end 18 and the mouth end 20.

The non-tobacco portion 16 comprises a core 27 intended to act for example as a cooler to cool slightly the vapour before it is inhaled by the user. The core 27 may comprise for this purpose for example corrugated paper. Advantageously, the core 27 is arranged inside the non-tobacco portion 16 to be entirely in contact with the internal surface of the wrapper 21 delimiting this non-tobacco portion 16.

The tobacco portion 15 comprises a vaporizable material and is intended to be heated by a heating chamber, as it will be explained in further detail below.

The tobacco portion 15 defines a first external surface 30 and a second external surface 32 opposite to the first external surface 30. In the example of Figure 2, the first and second external surfaces 30, 32 correspond to the external surface of the wide walls 14A, 14B.

Referring again to Figure 1 , the aerosol generating device 11 comprises a device body 40, extending along a device axis X’, and a mouthpiece 42. According to the example described below, the mouthpiece 42 and the device body 40 form two different pieces. Particularly, according to this example, the mouthpiece 42 is designed to be fixed on a fixing end of the device body 40.

As it is shown in Figure 3, the mouthpiece 42 comprises a central part 43 and a peripheral part 44 extending around the central part 43. The peripheral part 44 defines for example a collar covering partially an external surface of the device body 40 when the mouthpiece 42 is fixed on the fixing end of the device body 40. For example, the peripheral part 44 can be designed to cooperate with a gasket 45 arranged on the fixing end of the device body 40 in order to seal the space formed between the peripheral part 44 and the external surface of the device body 40. The central part 43 of the mouthpiece 42 defines a through-hole 46 adapted to receive at least partially the tobacco article 12. Particularly, the through-hole 46 can be adapted to receive at least a part of the non-tobacco portion 16 of the tobacco article 12 as it is shown in Figure 3. Advantageously, the through-hole 46 can be adapted to fit tightly the non-tobacco portion 16 of the tobacco article 12 so as to avoid or minimise flow leakage between a wall delimiting the through-hole 46 and an external surface of the tobacco article 12. In some embodiments, the tobacco article 12 can be retained for example by friction in the through-hole 46. In this case, it is possible for example to insert first the mouthpiece portion 16 of the tobacco article 12 inside the through-hole 46 and when fix both elements on the fixing end of the device body 40. As it is also shown in Figure 3, an inner volume 47 is formed between an inner surface 48 of the mouthpiece 42 and the fixing end of the device body 40. This inner volume 47 is crossed by the tobacco article 12 when it is inserted inside the device body 40. For example, the tobacco article 12 can divide the inner volume 47 in two symmetric parts.

The device body 40 delimits an internal space of the device 1 1 receiving various elements designed to carry out different functionalities of the device 1 1 . This internal space can for example receive a battery for powering the device 11 , a controller for controlling the operation of the device 11 , a flat-shaped heating chamber 50 (hereinafter “heating chamber 50”) for heating the tobacco portion 15 of the tobacco article 12, etc. Among these elements, only the flat-shaped heating chamber 50 will be explained in further detail in reference to Figure 3.

Particularly, as it is shown in Figure 3, the heating chamber 50 is configured to receive the tobacco article 12. The heating chamber 50 has a flat shape adapted to receive at least the tobacco portion 15 of the tobacco article 12. As the tobacco article 12, the heating chamber 50 may also form a cuboid shape extending along the device axis X’ and comprising a pair of parallel narrow walls (not visible) extending along the device axis X, a pair of parallel wide walls 54A, 54B extending also along the device axis X’ and a bottom wall 58 adjacent to each of said walls and extending perpendicularly to the device axis X. The bottom wall 58 thus forms a closed end of the chamber 50. Opposite to the bottom wall 58, the heating chamber 50 defines an opening configured to receive the tobacco article 12 so as the corresponding wide walls 14A, 14B of the tobacco article 12 face the corresponding wide walls 54A, 54B of the heating chamber 50, the corresponding narrow walls of the tobacco article 12 face the corresponding narrow walls 53A, 53B of the heating chamber 50 and the abutting end 18 of the tobacco article 12 faces the bottom wall 58.

In the example of Figure 3, the abutting end 18 of the tobacco article 12 faces the bottom wall 58 without being in contact with it. Alternatively the abutting end 18 of the tobacco article 12 abuts against the bottom wall 58. The facing wide walls 14A, 14B, 54A, 54B and the facing narrow walls 53A, 53B can be in contact one with the other or spaced one from the other.

As shown in Figure 3, the heating chamber 50 comprises a first heating plate 70A and a second heating plate 70B forming at least partially walls of the heating chamber 50, more particularly wide walls 54A, 54B of the heating chamber 50. Each heating plate 70A, 70B comprises a respective continuous heating surface 72A, 72B, advantageously a smooth heating surface 72A, 72B, configured to be in contact with an external surface 30, 32 of the tobacco portion 15. Advantageously, each heating surface 72A, 72B is flat.

In a variant (not shown), the heating chamber 50 comprises a long strip of flexible heater comprising two separate track patterns and wound around the heating chamber so those two patterns form the first and second heating surfaces 72A, 72B.

By “continuous” used in relation with a heating surface, it is meant that this surface has no discontinuous portions except its outer borders. In other words, a continuous heating surface extends continuously between its outer borders. Additionally, when a continuous heating surface is smooth, it has at least a first order derivative at each point except the outer borders.

When received within the heating chamber 50, the tobacco portion 15 is sandwiched between the two heating plates 70A, 70B. For example, as shown in Figure 3, the heating surface 72A of the first heating plate 70A is configured to be in contact with the first external surface 30 of the tobacco portion 15, while the heating surface 72B of the second heating plate 70B is configured to be in contact with the second external surface 32 of the tobacco portion 15.

Advantageously, the area of the heating surfaces 72A, 72B is designed to extend along only a partial area of the tobacco portion 15. In other words, the area of said heating surface 72A, 72B is smaller than the area of the corresponding external surface 30, 32 of the tobacco portion. For example, the area of said heating surface 72A, 72B is comprised between 35% and 99%, preferably between 40% and 95%, preferably between 40% and 90%, more preferably between 45% and 85%, more preferably between 50% and 80%, advantageously between 50% and 75%, of the area of the corresponding external surface 30, 32 of the tobacco portion 15.

In other words, as shown in Figure 4, the tobacco portion 15 protrudes from at least one end of the first heating plate 70A and/or the second heating plate 70B. Advantageously, as shown in Figure 4, the length and the width of the first heating plate 70A and/or second heating plate 70B are smaller than the length L15 and width W15 of the tobacco portion 15, so that the tobacco portion 15 protrudes from both ends of the first heating plate 70A and/or second heating plate 70B.

Advantageously, the area of the heating surface 72A, 72B of the first and/or second heating plate 70A, 70B is comprised between 15% and 60%, preferably between 20% and 50%, advantageously between 25% and 40%, of the area of an external surface of the flatshaped tobacco article 12.

For example, as shown in Figures 3 and 4, each heating plate 70A, 70B forms a flatshaped cuboid extending along the device longitudinal axis X’ and having external dimensions L70xW70xD70.

The heating plates 70A, 70B may have substantially the same dimensions. Alternatively, the heating plates 70A, 70B may have different dimensions.

Each heating plate 70A, 70B may present a homogeneous body 75 made from a same material, like as metal (like copper), ceramics, etc. Preferably, at least one or each heating plate 70A, 70B is made from a ceramic substrate, for example made of AI2O3, zirconia, silicon nitride or aluminum nitride. In a variant, the or each heating plate 70A, 70B is made of a resin substrate layer, such as polyimide for example.

The heating plates 70A, 70B may be made of the same material or of different materials, depending of the desired thermal properties.

The or each heating plate 70A, 70B comprises a heating element presenting for example a resistive element. Such a resistive element forms for example a resistive heating track 79, embedded into the body of the heating plate 70A, 70B and connected to the controller, as known per se. In the further description, by powering a heating plate, it is understood powering of the resistive element associated with the respective heating plate 70A, 70B.

According to the invention, the first and the second heating surfaces 72A, 72B are arranged opposite to each other according to an elevation axis Z perpendicular to each of the surfaces 72A, 72B, with an offset between the first and the second heating surfaces 72A, 72B according to an offset axis perpendicular to the elevation axis Z. In other words, a projection of the first heating surface 72A on the second heating surface 72B according to the elevation axis Z does not match said second heating surface 72B.

In particular, the first and the second heating plates 70A, 70B are arranged opposite to each other according to the elevation axis Z with an offset between the first and the second heating plates 70A, 70B according to the offset axis.

The first and the second heating surfaces 72A, 72B are arranged to form in a central plane arranged between the heating surfaces 72A, 72B at least one first zone 80 corresponding to an overlapping zone of orthogonal projections of the heating surfaces 72A, 72B in the central plane and at least one second zone 82 corresponding to a nonoverlapping zone of said orthogonal projections. The first and second heating surfaces 72A, 72B are asymmetrically arranged on either side of the central plane.

The tobacco portion 15 extending in the or each first zone 80 is thus heated from both sides, allowing a higher thermal penetration into the tobacco article 12, which enables to rapidly generate vapour with little energy, allowing a fast puff by a user. The tobacco portion 15 extending in the or each second zone 82 is heated from only one side. Vapour is thus generated after a longer time than in the first zone 80. In the first embodiment illustrated on Figures 3 to 5, the first and the second heating plates 70A, 70B are arranged in offset relative to each other along the device longitudinal axis X’. In other words, the offset axis is parallel to the device longitudinal axis X’.

Orthogonal projections P₇OA of the first heating plate 70A and orthogonal projections P₇OB of the first heating plate 70B in the central plane define one first zone 80 corresponding to an overlapping zone of orthogonal projections P₇OA, P₇OB in the central plane and two second zones 82 corresponding to a non-overlapping zone of said orthogonal projections P₇0A, P₇0B-

In the first embodiment, the first zone 80 is comprised between two second zones 82 and extends between said second zones 82 along the offset axis, which corresponds to the device longitudinal axis X’. The tobacco portion 15 is heated on both side only in a central region of said tobacco portion 15, while regions closer to the abutting end 18 of the tobacco article 12 or of the non-tobacco portion 16 are heated only on one side.

Advantageously, as visible on Figure 5, the first and the second heating plates 70A, 70B are arranged to further form in the central plane at least one third zone 84 corresponding to a non-overlapping zone of an orthogonal projection P15 of the tobacco portion 15 with said projections P₇OA, P₇OB of the heating plates 70A, 70B. In other words, as visible on Figure 4, the heating plates 70A, 70B are arranged so that the tobacco portion 15 comprises a non-sandwiched portion 86 whose corresponding external surfaces 30, 32 are in contact with neither the first heating plate 70A nor the second heating plate 70B.

The tobacco portion 15 extending in said third zone 84 is thus heated only via conduction within the tobacco portion and generates vapour after a longer time than in the second zone 82.

Advantageously, as visible on Figures 3 to 5, the third zone 84 is formed at a periphery of said orthogonal projection Pi₅ of the tobacco portion 15, preferably at least adjacent to the abutting end 18 of the tobacco portion 15, in order to further reduce vapour formed near the bottom wall 58 of the chamber 50. For example, as visible on Figure 5, the third zone 84 may surround at least partially the first and second zones 80, 82. The tobacco portion 15 is thus not heated by contact at its periphery. The controller (not shown) is configured to control the operation and particularly the powering of the or each heating surfaces 72A, 72B, in particular of each heating plate 70A, 70B, so that the or each heating surfaces 72A, 72B reaches a predetermined target temperature.

Said target temperature is for example comprised between 240°C and 320°C, for example equal to 280°C.

The first and the second heating surfaces 72A, 72B may be operated at different target temperatures. Particularly, the controller may be configured to power the first heating plate 70A according to a first target temperature and the second heating plate 70B according to a second target temperature. Each target temperature can be chosen based on the nature of the heating plate and notably, based on the heat capacity and/or position of each heating plate 70A, 70B. Thus, the heating of the tobacco portion can be optimized according to the different heat capacity and/or position of the heating plates 70A, 70B.

In some embodiments, at least one second zone 82 is designed to be adjacent to an orthogonal projection of the non-tobacco portion 16 in the central plane and the heating plate (here the first heating plate 70A) forming said second zone 82 is operated at a higher target temperature than the other heating plate 70B, the non-tobacco portion 16 acting as a cooling element.

DESCRIPTION OF A SECOND EMBODIMENT OF THE INVENTION

Figure 6 shows an aerosol generating assembly 10 according to a second embodiment of the invention.

The aerosol generating assembly 10 according to the second embodiment is similar to the aerosol generating assembly 10 according to the first embodiment explained above except the features described below.

In the second embodiment, the first and the second heating plates 70A, 70B are arranged in offset relative to each other along the device transversal axis Y’. In other words, the offset axis is parallel to the device transversal axis Y’. In the second embodiment, a first zone 80 is comprised between two second zones 82 and extends between two said second zones 82 along the offset axis, which corresponds to the device transversal axis Y’. The tobacco portion 15 is heated on both sides only in a central region of said tobacco portion 15, while regions closer to the narrow walls 13A, 13B of the article 12 are heated only on one side.

Advantageously, as illustrated on Figure 6, the heating plates 70A, 70B are arranged to further form in the central plane at least one third zone 84 at the abutting end 18 of the tobacco portion 15, in order to further reduce vapour formed near the bottom wall 58 of the chamber 50.

The heating plates 70A, 70B have here substantially the same dimensions. Alternatively, the heating plates 70A, 70B may have different dimensions.

DESCRIPTION OF A THIRD EMBODIMENT OF THE INVENTION

Figure 7 shows an aerosol generating assembly 10 according to a third embodiment of the invention.

The aerosol generating assembly 10 according to the third embodiment is similar to the aerosol generating assembly 10 according to the first embodiment explained above except the features described below.

In the third embodiment shown in Figure 7, the first and the second heating plates 70A, 70B are arranged in offset along both the device longitudinal axis X’ and the device transversal axis Y’. In other words, the offset axis has a longitudinal component parallel to the device longitudinal axis X’ and a transversal component parallel to the device transversal axis Y’.

In the third embodiment, a first zone 80 is comprised between two second zones 82 and extends between said second zones 82 along the offset axis. The tobacco portion 15 is heated on both sides only in a central region of said tobacco portion 15, while its periphery is heated only on one side. It is particularly advantageous to reduce vapour formed near the bottom wall 58 of the chamber 50. Advantageously, as visible on Figure 7, the first and the second heating plates 70A, 70B are arranged to further form in the central plane at least one third zone 84. Preferably, the third zone 84 is formed at a periphery of said orthogonal projection Pi₅ of the tobacco portion 15.

The third zone 84 forms for example a corner of said orthogonal projection P15 of the tobacco portion 15.

The heating plates 70A, 70B have here substantially the same dimensions. In a variant, shown in Figure 8, the heating plates 70A, 70B may have different dimensions.

It will be apparent to those skilled in the art that other embodiments may be carried out in various ways by combining the previous embodiments. Arrangements of the heating plates 70A, 70B with offset not shown on the Figures or with different dimensions may notably be chosen, depending on the desired heating properties.

Claims

1 . An aerosol generating device (11 ) configured to operate with a flat-shaped tobacco article (12) and comprising a flat-shaped heating chamber (50) extending along a device longitudinal axis (X’), the flat-shaped tobacco article (12) extending along an article longitudinal axis (X), and comprising a tobacco portion (15) and a non-tobacco portion (16) arranged successively along the article longitudinal axis (X), the tobacco portion (15) defining a first external surface (30) and a second external surface (32) opposite to the first external surface (30); the heating chamber (50) being configured to receive at least the tobacco portion (15) of the flat-shaped tobacco article (12), and comprising a first heating surface (72A) and a second heating surface (72B) configured to be in contact respectfully with the first external surface (30) and the second external surface (32) of the tobacco portion (15); wherein the first and the second heating surfaces (72A, 72B) are arranged opposite to each other according to an elevation axis (Z) perpendicular to each of the heating surfaces (72A, 72B), said first and second heating surface (72A, 72B) being in offset relative to each other according to an offset axis perpendicular to the elevation axis (Z).

2. The aerosol generating device (1 1 ) according to claim 1 , wherein the area of each heating surface (72A, 72B) is smaller than the area of the corresponding external surface (30, 32) of the tobacco portion (15).

3. The aerosol generating device (1 1 ) according to claim 1 or 2, wherein the first and the second heating surfaces (72A, 72B) are arranged to form in a central plane arranged between the heating surfaces (72A, 72B):

- at least one first zone (80) corresponding to an overlapping zone of orthogonal projections of the heating surfaces (72A, 72B) in the central plane;

- at least one second zone (82) corresponding to a non-overlapping zone of said orthogonal projections.

4. The aerosol generating device (1 1 ) according to claim 3, wherein at least one first zone (80) is comprised between two second zones (82).

5. The aerosol generating device (1 1 ) according to claim 4, wherein said first zone (80) extends between two said second zones (82) along the device longitudinal axis (X’) and/or along a device transversal axis (Y’) perpendicular to the device longitudinal axis (X’).

6. The aerosol generating device (11 ) according to any one of claims 3 to 5, wherein the first and the second heating surfaces (72A, 72B) are arranged to further form in the central plane at least one third zone (84) corresponding to a non-overlapping zone of an orthogonal projection of the tobacco portion (15) with said projections of the heating surfaces (72A, 72B).

7. The aerosol generating device (1 1 ) according to claim 6, wherein the third zone (84) is formed at a periphery of said orthogonal projection of the tobacco portion (15).

8. The aerosol generating device (1 1 ) according to claim 7, wherein the third zone (84) forms a corner of said orthogonal projection of the tobacco portion (15).

9. The aerosol generating device (11 ) according to any one of claims 6 to 8, wherein the third zone (84) surrounds at least partially said first and second zones (80, 82).

10. The aerosol generating device (11 ) according to claim any one of the preceding claims, wherein the first and the second heating surfaces (72A, 72B) are operated at different target temperatures.

1 1 . The aerosol generating device (1 1 ) according to any one of claims 3 to 9 taken in combination with claim 10, wherein:

- at least one second zone (82) is designed to be adjacent to an orthogonal projection of the non-tobacco portion (16) in the central plane;

- the heating surface (72A, 72B) forming said second zone (82) is operated at a higher target temperature than the other heating surfaces (72A, 72B).

12. The aerosol generating device (1 1 ) according to any one of the preceding claims, wherein the heating chamber (50) comprises a first heating plate (70A) and a second heating plate (70B) forming partially opposite walls of the heating chamber (50) and comprising respectively the first and second heating surfaces (72A, 72B), each heating plate (70A, 70B) including a planar substrate and a resistive heating track (79) embedded in or mounted on the planar substrate.

13. The aerosol generating device (11 ) according to claim 12, wherein the planar substrate of each heating plate (70A, 70B) comprises a rigid material, preferably chosen between ceramics and metal.

14. The aerosol generating device (11) according to claim 12, wherein the planar substrate of each heating plate (70A, 70B) comprises a flexible, heat-resistant resin, preferably chosen between polyimide and fluororesin.

15. The aerosol generating device (11 ) according to any one of claims 1 to 11 , wherein the heating chamber (50) comprises a long strip of flexible heater comprising two separate resistive track patterns and wound around the heating chamber (50) so the two separate resistive track patterns form the first and second heating surfaces (72A, 72B) respectively.