Aerosol Generating Device with Optimized Air Inlet Arrangement

The present invention concerns an aerosol generating device configured to operate with a consumable article comprising a substrate portion. The device comprises a heating chamber extending along a chamber axis, configured to receive at least the substrate portion and comprising a plurality of contact walls designed to be in contact with an external surface of the substrate portion. The plurality of contact walls comprises a bottom wall and at least one lateral wall. The heating chamber further comprises an inlet portion comprising an inlet hole of an airflow path extending through the substrate portion. Said inlet portion extends on the bottom wall and/or on the or at least one lateral wall to create an airflow gradient at least at a region of the heating chamber adjacent to this inlet portion.

FIELD OF THE INVENTION

The present invention concerns an aerosol generating device with optimized air inlet arrangement.

The aerosol generating device according to the invention is configured to operate with a consumable article comprising for example a solid substrate, also known as aerosol forming 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 an aerosol generating device known as a heat-not-burn device. Devices of this type generate aerosol or vapour by heating an aerosol forming substrate (usually a solid 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 by-products 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.

Regardless of the heating method used to heat a solid substrate, great care is taken to ensure even heating of the substrate. Particularly, it is known that if a tobacco containing substrate is heated too much, harmful chemicals may develop. If the temperature is too low, flavour and aerosol quantity are too low, hence reducing user experience. It is thus important to evenly heat the tobacco containing substrate at just the right temperature.

According to the prior art, this has been primarily achieved by focusing on the design of the heating element as well as the heating profile used to heat the substrate. This can be complicated and not optimal. For example, in the prevailing tobacco stick consumables, air is drawn in the bottom of the stick, even though this may not be the optimal design.

SUMMARY OF THE INVENTION

One of the aims of the invention is to provide an aerosol generating device allowing evenly heating of a solid substrate without using complex design of the heating element or special heating profiles.

For this purpose, the invention relates to an aerosol generating device configured to operate with a consumable article comprising a substrate portion containing a solid substrate and defining an external surface;the aerosol generating device comprising a heating chamber extending along a chamber axis and configured to receive at least the substrate portion of the consumable article;the heating chamber comprising a plurality of contact walls designed to be in contact with the external surface of the substrate portion of the consumable article, the plurality of contact walls comprising a bottom wall arranged substantially perpendicularly to the chamber axis and at least one lateral wall arranged substantially parallel to the chamber axis, the bottom wall being in contact with the or each lateral wall along a common border;the heating chamber further comprising a heating element extending from a centre of the bottom wall parallel to the or at least one lateral wall;the heating chamber further comprising an inlet portion comprising an inlet hole of an airflow path extending through the substrate portion of the consumable article when it is received in the heating chamber and when the device is operated to generate aerosol;said inlet portion extending on the bottom wall and/or on the or at least one lateral wall to create an airflow gradient at least at a region of the heating chamber adjacent to this inlet portion, said airflow gradient extending from the centre of the bottom wall until the common border.

Particularly, it was observed that in case of a single air inlet arranged in traditional aerosol generating devices in a centre bottom portion of the heating chamber, a cool zone is formed in the substrate portion of the consumable article near the corresponding inlet since the total quantity of fresh air passes through this zone. In this cool zone, the tobacco remains unconsumed. On the contrary, in a top portion of the substrate portion or in a portion immediately adjacent to a heating element, an overheated zone is usually formed. In this overheated zone, the tobacco may be burnt. Creating an airflow gradient toward the common border (i.e. a greater airflow in the periphery region of the substrate in comparison with its central region) makes it possible to counter this effect. Thus, cooling effect in the centre bottom portion of the substrate portion is reduced and heat may be more evenly distributed throughout this substrate portion.

According to some embodiments, said inlet portion extends:on the bottom wall, according to each transversal direction perpendicular to the chamber axis and passing through a centre of the bottom wall, from the common border until ⅜, preferably ¼, of the total length of the bottom wall according to this direction; oron the or at least one lateral wall, according to the chamber axis, preferably from the common border until ⅔ of the total length of this lateral wall according to this axis.

Arranging an air inlet portion close to a common border of the bottom and lateral walls of the heating chamber forces air entering in the periphery region of the substrate. Thus, an airflow gradient is created between the periphery and central regions.

According to some embodiments, said inlet portion comprises a plurality of inlet holes.

Thanks to these features, air can enter through several air inlets holes. Thus, contrary to a single air inlet case, only a part of the fresh air can pass through the corresponding inlet zone. This reduce cooling effect in the inlet zone.

According to some embodiments, the inlet portion extends on the bottom wall.

According to some embodiments, the concentration and/or the dimensions of the inlet holes increase(s) from the centre of the bottom wall to the common border.

Thanks to these features, a greater airflow is created in the periphery region of the substrate. Thus, an airflow gradient is created between the periphery and central regions

According to some embodiments, the inlet portion extends on the bottom wall.

According to some embodiments, the inlet holes are arranged symmetrically in respect with the centre of the bottom wall.

According to some embodiments, the inlet portion extends on the or at least one lateral wall.

According to some embodiments, at least two inlet holes are arranged according to the chamber axis, preferably homogeneously according to the chamber axis.

Thanks to these features, a better heat distribution inside the substrate portion of consumable article can be achieved.

According to some embodiments, the inlet portion extends on a unique lateral wall forming a cylindrical wall.

According to some embodiments, at least two inlet holes are arranged to face each other.

According to some embodiments, a plurality of inlet holes are arranged circumferentially on said cylindrical wall.

Thanks to these features, inlet holes can be arranged symmetrically in respect with a central axis passing through the device. This ensures more homogeneous heat distribution inside the substrate portion of the consumable article.

According to some embodiments, the substrate portion of the consumable article is wrapped in a wrapper, the wrapper comprising a plurality of openings;the inlet hole of the inlet portion being arranged to face said openings.

Thanks to these features, air can enter from the corresponding air inlet holes of the device directly inside the substrate portion of the consumable article, without passing through the wrapper. This ensures a better airflow throughout the consumable article and consequently, better aerosol generation.

According to some embodiments, the heating chamber comprises several inlet portions.

According to some embodiments, at least one inlet portion extends on the bottom wall and at least one inlet portion extends on the or at least one lateral wall.

Thanks to these features, inlet holes can be arranged on both bottom and at least one lateral walls. This can further improve heat transfer inside the substrate portion of consumable article.

According to some embodiments, the heating chamber further defines an open end opposite to the bottom wall.

Thanks to these features, the consumable article can be inserted at least partially in the heating chamber.

According to some embodiments, the or each inlet portion forms a unique air permeable portion on the corresponding contact wall.

Thanks to these features, the airflow inside the consumable article can be better controlled and predicted.

According to some embodiments, the or at least one inlet hole is arranged adjacent to the common border.

Thanks to these features, it is possible to achieve a more even air distribution inside the substrate portion of the consumable article.

DETAILED DESCRIPTION OF THE INVENTION

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.

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 heating 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 forming substrate” or “substrate” may refer to a material which may for example comprise nicotine or tobacco or any other smokable material, 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 former 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.

As used herein, the term “aerosol” may include a suspension of aerosol forming substrate 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 aerosol forming substrate.

An aerosol generating device10according to the invention is shown onFIG.1. This aerosol generating device10is designed to operate with a consumable article12also shown on this Figure.

Particularly, as it is shown onFIG.1, the consumable article12comprises a substrate portion14and a filter portion16. Both portions14,16can be wrapped using a unique wrapper18attaching these portions together. In other examples, the portions14,16may be wrapped by different wrappers and fixed one to the other by any other suitable mean. The or each wrapper18may, for example, comprise paper and/or non-woven fabric and/or aluminium. The or each wrapper18may be porous or air impermeable. Advantageously, according to the embodiments explained below, the or each wrapper18is air impermeable. Additionally, according to these embodiments, the or each wrapper18wraps the corresponding portions14,16only circumferentially. This means that the corresponding ends of the portions14,16can be unwrapped. The consumable article12can have a generally tubular shape defining for example a circular or elliptical cross-section. According to another example, the consumable article12defines a rectangular cross-section.

The substrate portion14contains an aerosol forming substrate intended to be heated by a heating chamber of the aerosol generating device10as it will be explained in further detail below. According to the invention, the aerosol forming substrate comprises a solid substrate. As mentioned above, the solid substrate can comprise shredded tobacco. The shredded tobacco can be advantageously substantially aligned along the direction of extension of the consumable article12. Additionally, according to some examples, the substrate portion14may comprise one or several susceptors integrated into the aerosol forming substrate. The susceptors may be formed from electrical conductor materials able to generate eddy currents when placed within a magnetic field. Eddy currents cause the susceptors to generate heat suitable for heating the aerosol forming substrate to generate aerosol. The magnetic field can be generated by a coil comprised in a heating system of the aerosol generating device10. The substrate portion14may comprise two or more adjacent segments with at least an upstream segment containing an aerosol forming substrate and a downstream segment forming spacer or cooling segment. The downstream segment can be a tube, for example, made of paper or other rigid material such as PLA material. The tube may be hollow or partially filled or reinforced by internal, e.g. radial and/or longitudinal, walls.

The filter portion16comprises a core acting for example like a filter. The core may for example be a foam, or packed strands or fibres. In some examples, the filter portion16can form a mouthpiece intended to be in contact with the user's lips and/or mouth while using the device10. In some other examples, the filter portion16can be inserted into a separate mouthpiece intended to be in contact with the user's lips and/or mouth. According to some other examples, the consumable article12can comprise only the substrate portion14.

The aerosol generating device10comprises a housing20defining an insertion opening21suitable for insertion of the consumable article12. The housing20delimits an internal space of the device10receiving various elements designed to carry out different functionalities of the device10. This internal space can for example receive a battery23for powering the device10, a control module24for controlling the operation of the device10, and a heating chamber25configured to receive and heat at least a part of the consumable article12. Among these elements, only the heating chamber25will be explained in further detail. The other elements, as for example the battery23and the control module24, can be implemented using known techniques.

The heating chamber25extends along a chamber axis X between a closed end30and an open end31, and has substantially the same cross-sectional shape as the consumable article12. The open end31opens to the insertion opening21of the housing20. As it is shown onFIG.1, the heating chamber25is adapted to receive the substrate portion14of the consumable article12through the open end31so as this substrate portion14extends inside the heating chamber25along the chamber axis X. Additionally, as mentioned above, the heating chamber25is adapted to heat at least a part of the substrate portion14.

For this purpose, the heating chamber25comprises a heating element34which is formed in the example ofFIG.1by a heating blade. Such a heating blade is configured to penetrate inside the substrate portion14of the consumable article12while its insertion. The operation of the heating element34may be controlled by the control module24using control methods known per se.

The heating chamber25comprises a plurality of contact walls designed to be in contact with an external surface of the substrate portion14of the consumable article12. In the example ofFIG.1, this external surface is formed by the part of the wrapper18received in the heating chamber25and the unwrapped end of the substrate portion14. The contact walls comprises a bottom wall40arranged substantially perpendicularly to the chamber axis X and at least one lateral wall41arranged substantially parallel to the chamber axis X. The bottom wall40is in contact with the or each lateral wall41along a common border42and defines a centre C. The heating element34extends from the centre C according to the chamber axis X. The centre C of the bottom wall40is defined as a geometrical centre of this wall which can be determined according to the shape of the bottom wall40. For example, when the bottom wall40has a circular shape, the centre C is the centre of the circle forming this shape. When the bottom wall40has a rectangular shape, the centre C is the intersection point of its diagonals. When the bottom wall40has a more complicated shape, the centre C can be defined as the centre of mass of the corresponding shape.

In the example ofFIG.1, the heating chamber25defines generally tubular shape having for example a circular cross-section. In this, case a single lateral wall41is arranged parallel to the chamber axis X. Additionally, in the example ofFIG.1, the lateral wall41of the heating chamber25is in contact with the wrapper18whereas the bottom wall40is in contact with the unwrapped end of the substrate portion14.

According to the invention, the heating chamber25further comprises an inlet portion comprising at least one inlet hole making it possible air entering inside the substrate portion14of the consumable article12. The or each inlet hole is in fluid communication with one or several air inlets arranged for example in the housing20of the device10. Thus, at least one airflow path is formed inside the housing20and extends through the substrate portion14of the consumable article12when it is received in the heating chamber25and when the device10is operated to generate aerosol. According to different embodiments of the invention explained in further detail below, the inlet portion extends on the bottom wall40and/or on the or at least one lateral wall41to create an airflow gradient at least at a region of the heating chamber35adjacent to this inlet portion. The airflow gradient extends from the centre C of the bottom wall40until the common border42.

Particularly, by “airflow gradient”, it is understood a change of airflow (i.e. airflow rate) between at least two different points of the substrate portion14when it is received in the heating chamber25and the device10is operated to generate aerosol. According to the invention, such an airflow gradient extends from the centre C of the bottom wall40until the common border42which means that a greater airflow is generated in regions adjacent to the or at least one lateral wall41than an airflow generated in regions adjacent to the heating element34. In order to achieve such a gradient, several embodiments are possible.

A detailed view of the bottom wall40according to the first embodiment of the invention is shown onFIG.2.

Particularly, according to the first embodiment of the invention, the heating chamber25comprises an inlet portion45which extends on the whole bottom wall40of the heating chamber25and defines a plurality of inlet holes. In order to ensure an airflow gradient extending from the centre C until the common border42, the concentration and/or the dimensions of the inlet holes increase from the centre C of the bottom wall40to the common border42. The holes can be arranged for example symmetrically in respect with the centre C.

In the example ofFIG.2, the bottom wall40has a circular shape. In the examples A), D), and G) of this Figure, the holes formed in the inlet portion45has a circular shape with a diameter increasing from the centre C until the common border42. In the example C) of this Figure, the circular holes have a same diameter but their number is greater near the common border42than near the centre C. In the examples B) and E) of this Figure, the holes extend according to several circumferential directions and are comprised within one or several arcs. Thus, their area increases from the centre C to the common border42. Finally, in the example F) of this Figure, the holes have a rectangular shape oriented toward the centre C. Of course, other hole arrangements and/or shapes can be applied.

A detailed view of a part of the heating chamber25according to the second embodiment of the invention is shown onFIG.3.

Particularly, according to the second embodiment of the invention, the heating chamber25comprises an inlet portion which extends on the bottom wall40according to each transversal direction Y perpendicular to the chamber axis X and passing through the centre C of the bottom wall40, from the common border42until ¼ of the total length L1of the bottom wall40according to this direction Y. Additionally, the length L1of the bottom wall41according to a transversal direction Y passing through the centre C is measured along its surface which is in contact with the external surface of the consumable article12. In other words, this length L1does not include the eventual thickness of one or several lateral walls41. In the example ofFIG.3, the length L1is measured between the internal surfaces of the lateral wall41which are intended to be in contact with the wrapper18of the consumable article12. It is also clear that when the bottom wall40has a circular shape, the length L1according to each transversal direction Y presents the same value.

According to the example ofFIG.3, a circumferential inlet portion50adjacent to the common border42is formed around the heating element34. When the bottom wall40presents a non-circular shape, the inlet portion50is defined as a peripheral zone adjacent to the common border42and extending according to each transversal direction Y passing through the centre C until ¼ of the total length L1of the bottom wall40according to this direction Y. For example, the inlet portion50can be symmetric in respect with the centre C of the bottom wall42.

The inlet portion50comprises at least one inlet hole making it possible air entering inside the substrate portion14of the consumable article12. The or each inlet hole is in fluid communication with one or several air inlets arranged for example in the housing20of the device10. Thus, at least one airflow path is formed inside the housing20. When the substrate portion14is received in the heating chamber25, the or each airflow path extends through this substrate portion14and through the filter portion16of the consumable article12until the non-wrapped end of the filter portion16. Several airflow paths inside the substrate portion14are shown in the example ofFIG.3. Advantageously, according to the invention, said inlet hole(s) is(are) the unique opening(s) formed in the walls of the heating chamber25.

In the example ofFIG.3, the inlet portion50comprises two triplets of inlet holes52A,52B arranged for example on either side of the heating element34according to the same transversal direction Y. In each triplet, the inlet holes can for example be homogeneously along said transversal direction Y. According to another example, the inlet portion50can comprise for example only one inlet hole which can have a greater diameter than the inlet holes of the triplets52A,52B. According to still another example, the inlet portion50can define a plurality of inlet holes arranged according to one or several circumferential directions. Along the corresponding circumferential direction, the inlet holes can for example be arranged homogeneously. According to still another example, the inlet portion50can define a plurality of inlet holes arranged symmetrically in respect with the centre C of the bottom wall40. According to still another example, one or several inlet holes can be arranged adjacent to the common border42. According to still another example, the second embodiment can be combined with the first embodiment. Particularly, in this case, the inlet portion50as defined in relation with the second embodiment, can comprise a plurality of holes those dimensions and/or concentration increase(s) from an internal border surrounding the centre C to the common border42. In this case, the holes can be formed/arranged as shown in the examples ofFIG.2where a central region is excluded from the corresponding inlet portion. Of course, other examples of inlet holes arrangement and their number are still possible.

Additionally, it is clear that when the inlet holes are formed in the bottom wall40of the heating chamber25and the corresponding end of the substrate portion14is unwrapped, no additional opening is necessary on the wrapper18. In some cases, the wrapper18may comprise openings which may be closed by the lateral wall41of the heating chamber25when the substrate portion14is inserted therein.

FIG.4shows an example of the heating chamber25according to the third embodiment of the invention.

Particularly, according to the third embodiment of the invention, the heating chamber25comprises at least one inlet portion which extends on the or at least one lateral wall41, according to the chamber axis X, from the common border42until ⅔ of the total length L2of this lateral wall according to this axis X. As in the previous case, the length L2of the or at least one lateral wall is measured along to its surface which is in contact with the external surface of the consumable article12. In other words, in the example ofFIG.4, the length L2is measured along the chamber axis X between the bottom wall40and the open end31of the heating chamber25.

In the example ofFIG.4, an inlet portion60is formed circumferentially on the lateral wall41to be adjacent to the common border42. As mentioned above, this inlet portion60extends from the common border42along the chamber axis X according to ⅔ of the length L2of the lateral wall41according to this axis X.

As in the previous embodiment, the inlet portion60forms at least one inlet hole which is in fluid communication with one or several air inlets arranged in the housing20of the device10. Thus, one or several airflow paths are formed inside the housing20and extend then through the substrate portion14and the filter portion16of the consumable article12until the non-wrapped end of the filter portion16. These paths inside the substrate portion14are shown onFIG.4.

In the example ofFIG.4, the inlet portion60comprises two triplets of inlet holes62A,62B. The triplets62A,62B can for example be arranged to face each other. In each triplet62A,62B, the inlet holes can be arranged homogenously according to the chamber X. Additionally, at least two inlet holes of different triplets62A,62B can be arranged according to the same transversal direction Y. According to another example, the inlet portion60can comprise for example only one inlet hole which can have a greater diameter than the inlet holes of the triplets62A,62B. According to still another example, the inlet portion60can define a plurality of inlet holes arranged according to one or several circumferential directions extending through the lateral wall41. Along the corresponding circumferential direction, the inlet holes can for example be arranged homogeneously. According to still another example, the inlet portion60can define a plurality of inlet holes arranged symmetrically in respect with a centre axis passing though the centre C of the bottom wall40parallel to the chamber axis X. According to still another example, one or several inlet holes can be arranged adjacent to the common border42. Of course, other examples of inlet holes arrangement and their number are still possible.

Additionally, in the example ofFIG.4, the heating element34extends from the centre C of the bottom wall40and no inlet hole40is formed in this wall. However, in a general case, at least one inlet hole may be formed in the bottom wall40. For example, when the heating is performed by an element other than the heating blade34, an inlet hole may be formed at the centre C of the bottom wall40.

According to the third embodiment of the invention, the wrapper18of the consumable article12forms advantageously an opening facing each inlet hole. In this case, the wrapper18can comprise a label or any other key element indicating to the user the right insertion orientation of the consumable article12in the heating chamber25. According to another example, the wrapper18can be formed at least partially from an air permeable material.

FIG.5shows the heating chamber25according to the fourth embodiment of the invention. This embodiment corresponds to a combination of the previous two embodiments and in some cases, of all of the three previous embodiments.

Particularly, according to the fourth embodiment, an inlet portion is formed on the bottom wall40and an inlet portion is formed on at least one lateral wall41of the heating chamber25. Each of these inlet portions is similar to the respective inlet portion explained above. Thus, the inlet portion formed on the bottom wall40extends on this wall40according to each transversal direction Y perpendicular to the chamber axis X and passing through a centre C of the bottom wall40, from the common border42until ¼ of the total length L1of the bottom wall40according to this direction Y. Similarly, the inlet portion formed on at least one lateral wall41extends on this lateral wall41, according to the chamber axis X, from the common border42until ⅔ of the total length L2of this lateral wall according to this axis X.

In the example ofFIG.5, an inlet portion50is formed on the bottom wall40and an inlet portion60is formed one the lateral wall41.

Additionally, as in the previous cases, each inlet portion50,60comprises at least one inlet hole similar to the inlet holes explained above. For example, as shown onFIG.5, the inlet portion50of the bottom wall40can form two inlet holes arranged according the same transversal direction Y and the inlet portion60can form two triplets of inlet holes facing each other. These inlet holes form several airflow paths inside the substrate portion14as shown onFIG.5.

According to another embodiment (not shown), the third embodiment is combined with the first embodiment to form a bottom wall42as shown in one the examples ofFIG.2and a lateral wall41as shown onFIG.4.