WO2024126100A1

WO2024126100A1 - Aerosol generating device

Info

Publication number: WO2024126100A1
Application number: PCT/EP2023/083946
Authority: WO
Inventors: Jaakko MCEVOY
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2022-12-14
Filing date: 2023-12-01
Publication date: 2024-06-20
Anticipated expiration: 2025-06-14

Abstract

An aerosol generating device (100) configured to generate an aerosol for inhalation by a user is disclosed, comprising: a first planar heater (104) and a second planar heater (106) controllable independently from the first heater, each arranged to heat different surfaces of a consumable and configured to heat an aerosol forming substance to generate an aerosol; a cavity (108) provided between the first heater and the second heater, configured to receive the aerosol forming substance; and a controller (114) configured to operate the first heater and the second heater by setting target heating temperatures for the first heater and the second heater using a first temperature profile (200) and a second temperature profile (210), respectively; wherein, at all times during the first temperature profile or the second temperature profile, the target heating temperature of the first temperature profile is higher than the target heating temperature of the second temperature profile.

Description

AEROSOL GENERATING DEVICE

FIELD OF INVENTION

The invention relates to aerosol generating devices. In particular, the invention relates to aerosol generating devices with independently heatable heaters.

BACKGROUND TO THE INVENTION

Aerosol generating devices can generate an aerosol by heating a consumable including an aerosol generating substance above an aerosol generating temperature, using one or more heaters. The choice of temperature profile for the heater or heaters during an aerosol generation session strongly affects the quality of the aerosol and the efficiency of the aerosol generating device. For example, a high vapour volume can be achieved using high temperatures at the start of the session, which is enjoyable for the user, but this increases the energy consumption of the device. In another example, using a flat temperature profile for heaters in the session can provide a poor sensory experience for the user and fails to account for changes in the properties of the aerosol generating substance over the course of a session. There is therefore a demand to balance the competing requirements of vapour quality and device efficiency. Additionally, different types of consumables and heaters require different temperature profiles for maximising aerosol quality and device efficiency.

Aerosol generating devices can also become hot in use, which can pose a comfort risk for the user holding the aerosol generating device. There is therefore a demand for better thermal management of aerosol generating devices.

SUMMARY OF INVENTION

According to an aspect of the invention there is provided an aerosol generating device configured to generate an aerosol for inhalation by a user, comprising: a first planar heater and a second planar heater controllable independently from the first heater, each configured to heat an aerosol forming substance to generate an aerosol; a cavity provided between the first heater and the second heater, configured to receive the aerosol forming substance; and a controller configured to operate the first heater and the second heater by setting target heating temperatures for the first heater and the second heater using a first temperature profile and a second temperature profile, respectively; wherein, at any time during the first temperature profile or the second temperature profile, the target heating temperature of the first temperature profile is higher than the target heating temperature of the second temperature profile.

In this way, the first heater operates at a higher temperature than the second heater for the entirety of an aerosol generating (or “vaping”) session. This allows the aerosol generating device to heat a consumable comprising the aerosol generating substance having a larger surface area on one side (or surface) more evenly when placed into the cavity with side having the larger surface area adjacent the second heater. Heating the consumable more evenly produces a higher quality aerosol.

Furthermore, having only one heater in operation during a vaping session has been found to provide a cooler vapour that is less enjoyable for the user. By having one heater at a higher temperature for aerosol generation and the remaining heater at a lower, moderately high temperature, the lower temperature heater can heat the aerosol received by the user to provide a more enjoyable aerosol. Additionally, setting one heater to a lower temperature reduces the heat flux onto the substrate from one side, meaning that the other heater has a preferrable thermal gradient and can theoretically push more energy into the substrate from its corresponding side.

The first temperature profile and the second temperature profile each comprise a plurality of target heating temperatures. It should be understood that the term “target heating temperature” refers to an aerosol generation temperature and can therefore be distinguished from a non-heating target temperature. For example, an ambient temperature would be a non-heating target temperature applied when the first and second heater are not in use or the aerosol generating device is turned off. Furthermore, the skilled person would understand that “target heating temperature” refers to a desired temperature that may not reflect the actual temperature of the first or second heater at a given moment. In general, the actual temperature of the first or second heater lags behind the target heating temperature. The amount of lag is influenced by the change in electrical power provided to the heaters when switching between different target heating temperatures as well as other factors such as the material used in the heaters, the ambient temperature, and the depletion level of an aerosol forming substance in the cavity.

The first heater and the second heater are controllable independently. In one example, the first and second heaters may be wired separately to the controller so that the controller can control the delivery of electrical power to each heater independently. In other examples, any control electronics that enable the first and second heater to operate at different temperatures at the same point in time may be implemented.

Planar heaters are known to be able to heat a planar consumable more quickly compared to other arrangements of heaters and consumables, such as cylindrical heaters and consumables. It is therefore desirable to use such a heating assembly in aerosol generating devices. The first and second temperature profiles of the invention have been found to be particularly suitable for planar heaters. The first heater may be a first planar heater and the second heater may be a second planar heater. The cavity is preferably provided in a layer between the first planar heater and the second planar heater, wherein each heater provides a layer adjacent to the cavity. The cavity may be configured to receive a planar consumable through a door or other suitable opening in a housing of the aerosol generating device. The first and second planar heaters may have a rectangular shape. Other suitable shapes, such as circular or square, may also be implemented. In a further example, each of the first and second planar heater could comprise a plurality of adjacent separated sections arranged in a common plane. The first and second planar heaters may each comprise a single planar surface. Alternatively, the first and second planar heaters may comprise a respective plurality of adjacent separated sections arranged in a common plane.

The first and second heaters, which may be planar heaters, may be configured to generate heat using electrical resistive heating.

In other examples, the first and second heaters may have other, non-planar shapes, such as a rod shape configured to penetrate a consumable, or a curved film shape lining the walls of the cavity for receiving the aerosol generating substance.

The first heater and the second heater may be arranged to face different areas of an aerosol generating consumable. The cavity may also be at least partially formed by the first heater and the second heater. The first heater and the second heater may be planar or non-planar, in these examples.

The first temperature profile preferably comprises an initial target heating temperature, a final target heating temperature, a maximum target heating temperature and a minimum target heating temperature. The second temperature profile preferably comprises an initial target heating temperature, a final target heating temperature, a maximum target heating temperature and a minimum target heating temperature.

The maximum target heating temperature for the first heating profile may correspond to a maximum rate of aerosol generation that is acceptable to avoid an overly rapid depletion of the aerosol generating substance. Similarly, the minimum target heating temperature may correspond to a minimum rate of aerosol generation that is acceptable for providing a good quality aerosol.

The maximum and minimum target heating temperatures may be selected based on the boiling point of ingredients in the aerosol generating substance. In one example, the maximum, initial, and minimum target heating temperatures can be 260 °C, 230 °C, and 180 °C, respectively. In this case, the aerosol generating substance may include ingredients with boiling points between 180 °C and 260 °C.

Preferably, the initial target heating temperature of the first temperature profile is equal to the maximum target heating temperature of the first temperature profile. In one example, the initial target heating temperature of the first temperature profile is about 270°C. Having an initially high target heating temperature can also produce a high vapour volume at the start of the session, which is enjoyable for the user.

Preferably, the second temperature profile comprises a plurality of target heating temperatures that decrease progressively from the initial to the final target heating temperature of the second temperature profile. In this way, the efficiency of the device can be increased. This is achieved because the actual operating temperature of each heater lags behind their corresponding target heating temperature. By transitioning to successively lower target heating temperatures the energy consumption of the second heater is reduced in the period following each transition due to the lower power required to maintain the heater at lower temperatures. Meanwhile, the actual temperature of the second heater decreases more gradually. This momentarily allows the second heater to have a higher temperature while expending less energy. Conserving energy by dropping the target heating temperature without allowing a significant drop in actual heater temperature can also be described as “temperature coasting”.

Put differently, the area under a temperature profile of target heating temperatures is proportional to, or at least correlates with, the energy consumption of the corresponding heater. Thus, including large drops in a temperature profile can significantly reduce the energy consumption of the profile without necessarily causing undesirable sudden drops in the actual temperature of the heater, due to the lagging effect.

Additionally, using an initially high target heating temperature can produce a high vapour volume at the start of the session, which is enjoyable for the user. The second temperature profile can comprise three, four, five, or more progressively decreasing target heating temperatures.

Preferably, the maximum target heating temperature of the second temperature profile is greater than the minimum target heating temperature of the first temperature profile. This has been found to provide a particularly effective balance between efficiency and vapour quality for the arrangement of two heaters with the cavity positioned between them. In addition, this ensures that the first and second heaters are operating in similar temperature ranges to promote more even heating of the consumable. This also allows for the depletion of the consumable at different rates at different times during a vaping session and at different locations in the consumable. Varying the depletion of the consumable in this way has been found to generate more vapour and deplete the consumable more evenly, leading to a higher quality aerosol.

Preferably, the difference between the initial target heating temperature of the first temperature profile and the initial target heating temperature of the second temperature profile is less than the difference between the final target heating temperature of the first temperature profile and the final target heating temperature of the second temperature profile. This has been found to provide a particularly effective balance between efficiency and vapour quality for the arrangement of two heaters with the cavity positioned between them. In one example, the difference between initial target heating temperatures can be about 40°C and the difference between final target heating temperatures can be about 50°C.

Preferably, the difference in target heating temperatures between the first temperature profile and the second temperature profile is greatest at the end of the first and second temperature profiles compared to any other time during the first or second temperature profiles. This has been found to provide a particularly effective balance between efficiency and vapour quality for the arrangement of two heaters with the cavity positioned between them. Preferably, the first temperature profile comprises at least one decrease and at least one increase in target heating temperature. Preferably, the increase occurs after the decrease. More preferably, the target heating temperature before the decrease is equal to the target heating temperature after the increase. This enables the first temperature profile to benefit from temperature coasting.

Preferably, the first heater is positioned adjacent a first external surface of the aerosol generating device, the second heater is positioned adjacent a second external surface of the aerosol generating device, and the aerosol generating device is configured to be held in use preferentially with the second external surface having a greater surface area in contact with a user than the first external surface.

In general, users hold aerosol generating devices with an overhand grip, or with two fingers on an upper external surface and a thumb on a lower external surface. In either case, the upper surface generally has more surface area in contact with the user than the lower surface. High operating temperatures of the first and second heaters can cause external surfaces of the aerosol generating device to reach moderately high temperatures. Positioning the first and second heaters in this orientation makes the aerosol generating device more comfortable to hold because the first heater, which operates at higher temperatures compared to the second heater, is positioned at the side of less contact surface area with the user. Thus, the likelihood of a hotspot forming at the region of most contact with the user is reduced.

The aerosol generating device can be configured to be held preferentially in a particular orientation in several ways. In one example, an input mechanism may be positioned to encourage the user to hold the aerosol generating device in a particular orientation. In other examples, the aerosol generating device can have an ergonomic shape, or an indicator such as a light source or surface marking, that encourages the user to grip the aerosol generating device so that the second external surface has more contact with the user. The first external surface and the second external surface can be different sides of the same continuous surface of a housing of the aerosol generating device. Alternatively, the first and second external surfaces can be different surfaces of a housing.

Preferably, the first heater and/or the second heater comprise ceramic. This has been found to provide a particularly effective balance between efficiency and vapour quality for the arrangement of two heaters with the cavity positioned inbetween, in conjunction with the features of the first and second temperature profiles described above. In particular, ceramic heaters generally have a higher specific heat capacity compared to metal heaters and therefore require specifically tailored temperature profiles. The higher specific heat capacity of ceramic heaters means the actual temperatures of the first and second heaters can drop more slowly compared to some metal heaters. This is due to their higher specific heat capacity causing the actual temperature of the heaters to lag behind their target heating temperature to a greater extent and allows ceramic heaters to derive a greater benefit from temperature coasting.

Preferably, the first temperature profile and the second temperature profile are configured for heating an aerosol forming substance comprising tobacco. The temperature profiles of the present invention have been found to provide a particularly effective balance between efficiency and vapour quality for the arrangement of two heaters with the cavity positioned in-between, in conjunction with the use of tobacco as an aerosol generating substance. This is particularly the case when the first and second heaters comprise ceramic and are planar. For example, the maximum and minimum target heating temperatures of the first and second temperature profiles may be selected based on known properties of tobacco to generate a high vapour volume without burning the tobacco.

Preferably, the first heater is substantially planar and the second heater is substantially planar. In this way, the first and second temperature profiles provide a particularly effective balance between vapour quality and device efficiency because the first and second temperature profiles have been found to be particularly effective for such an arrangement of heaters. The first heater and the second heater can also be arranged to heat two different surfaces of a consumable. According to a further aspect of the invention there is provided a method of operating an aerosol generating device comprising a first heater and a second heater controllable independently from the first heater, comprising: operating the first heater and the second heater by setting target heating temperatures for the first heater and the second heater using a first temperature profile and a second temperature profile, respectively; wherein, at any time during the first temperature profile or the second temperature profile, the target heating temperature of the first temperature profile is higher than the target heating temperature of the second temperature profile.

According to a further aspect of the invention there is provided a non-transitory computer readable medium comprising executable instructions that, when executed by a processor on an aerosol generating device comprising a first heater and a second heater controllable independently from the first heater, cause the aerosol generating device to perform steps comprising: operating the first heater and the second heater by setting target heating temperatures for the first heater and the second heater using a first temperature profile and a second temperature profile, respectively; wherein, at any time during the first temperature profile or the second temperature profile, the target heating temperature of the first temperature profile is higher than the target heating temperature of the second temperature profile.

According to a further aspect of the invention, there is provided an aerosol generating device configured to generate an aerosol for inhalation by a user, comprising: a first heater and a second heater controllable independently from the first heater, arranged to face different areas of an aerosol generating consumable and configured to heat the consumable to generate an aerosol; a cavity at least partially formed by the first heater and the second heater, configured to receive the consumable; and a controller configured to operate the first heater and the second heater by setting target heating temperatures for the first heater and the second heater using a first temperature profile and a second temperature profile, respectively; wherein, at any time during the first temperature profile or the second temperature profile, the target heating temperature of the first temperature profile is higher than the target heating temperature of the second temperature profile.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are now described, by way of example, with reference to the drawings, in which:

Figure 1 shows a schematic cross-sectional diagram of an aerosol generating device according to an embodiment of the invention;

Figure 2 shows a schematic control diagram according to an embodiment of the invention;

Figure 3 shows a schematic cross-sectional view of a heating apparatus in use according to an embodiment of the invention;

Figure 4 shows a schematic perspective view of a consumable suitable for use with an embodiment of the invention;

Figure 5 shows an end view of a consumable suitable for use with an embodiment of the invention;

Figure 6 shows a schematic perspective view of an aerosol generating device according to an embodiment of the invention;

Figure 7 shows a schematic cross-sectional diagram of an aerosol generating device according to an embodiment of the invention; and

Figure 8 shows a graph plotting a first temperature profile and a second temperature profile according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 shows a schematic diagram of an aerosol generating device 100 according to an embodiment of the invention. The aerosol generating device 100 comprises a tubular housing 102 for containing and protecting the internal components of the aerosol generating device 100. A first planar heater 104 and a second planar heater 106 are provided in a substantially parallel orientation, spaced apart to create a cavity 108 in a layer between them. Each of the first planar heater 104 and the second planar heater 106 are configured to heat an aerosol generating substance received in the cavity 108. The housing 102 may comprise a mechanism (not shown), such as a door or a removable part that enables insertion of the aerosol generating substance into the cavity 108. An air inlet 110 is provided on the housing 102 and is fluidically connected to the cavity 108. An airflow channel (A) connects the cavity 108 to an air outlet 113 provided on a mouthpiece 112 to enable a user to draw air from the air inlet 110 through the cavity 108.

A controller 114 is provided and is configured to control target heating temperatures of the first planar heater 104 and the second planar heater 106 using a first temperature profile and a second temperature profile, respectively. A button 116 is provided on the housing 102 in electrical connection with the controller 114 for enabling a user to initiate aerosol generation. A battery 118 is provided for providing power to the first planar heater 104, the second planar heater 106, the controller 114, and any other electric components of the aerosol generating device 100.

Figure 2 shows a schematic control diagram of the aerosol generating device 100. The controller 114 comprises at least one processor 114a and a memory 114b for executing and storing executable instructions 114c, respectively. The instructions 114c include instructions for implementing the first and second temperature profiles. The controller 114 is configured to receive or send signals from the components shown in Figure 2 to control the various operations of the aerosol generating device 100.

Temperature sensors 107 are provided on or near the first and second planar heaters 104, 106 for monitoring the temperature of each of the first and second planar heaters 104, 106. The temperature sensors 107 are connected to the controller 114 for relaying temperature measurements, or, alternatively, relaying data from which a temperature measurement can be determined by the controller 114. Temperature can be measured directly using sensors such as a thermocouple or indirectly by measuring a property such as electrical resistance.

The housing 102 may comprise any suitable material known in the art, such as plastic or metal. The housing 102 has a tubular shape which can have any suitable cross section, such as a square, oval or circular cross section. The housing 102 comprises a first external surface 102a and a second external surface 102b. The first planar heater 104 is positioned closest to the first external surface 102a. The second planar heater 106 is positioned closest to the second external surface 102b. In the example embodiment of Figure 1 the button 116 is positioned on the second external surface 102b. This encourages the user to hold the aerosol generating device 100 with the second external surface 102b pointing upwards so that the button 116 can be pressed with an index finger in an overhand grip. In other embodiments, the housing 102 may have other features that encourage the user to hold the aerosol generating device 100 in this orientation. In one example, the housing 102 can have an ergonomic shape designed to be held in an orientation with the second external surface 102b oriented upwards, i.e. oriented at the user’s upper lip rather than their lower lip.

In other embodiments, the button 116 can be replaced with or used alongside any other suitable input mechanism, such as a fingerprint sensor, a gesture sensor, or an air flow sensor. The battery 118 may be permanently fixed within the housing 102 and rechargeable. Alternatively, the battery 118 may be removable. In other embodiments, the aerosol generating device may be provided without a battery 118 and the user may supply a separate battery pack or disposable power source.

The first planar heater 104 and the second planar heater 106 form a heating assembly 120, as shown in a cross-sectional view in Figure 3 with a consumable 10 including tobacco as an aerosol generating substance placed in the cavity 108. Figures 1 and 3 show a simplified depiction of the aerosol generating device 100 and the heating assembly 120. Figures 6 and 7 show the aerosol generating device 100 and the heating assembly 120 in greater detail.

The consumable 10 has a substantially planar shape and comprises a plurality of air channels 32 positioned on alternating sides of the consumable 10, such that the consumable 10 also has a corrugated shape. The air channels 32 are advantageous for improving airflow through the consumable 10 so that a user can draw generated aerosol from the cavity 108 more easily. There are a greater number of air channels 32 on the side of the consumable 10 adjacent the first planar heater 104 compared to the side adjacent the second planar heater 106. This causes the “upper” side, from the perspective of Figure 3, to have a larger surface area in contact with the second planar heater 106 compared to the “lower” side of the consumable 10 with the first planar heater 104. As described further below, the first and second temperature profiles are configured to compensate for this difference in contacting surface area between each side of the consumable 10.

In the example of Figure 3, there are three air channels 32 adjacent the first planar heater 104 and two air channels 32 adjacent the second planar heater 106. Other consumables may have a larger or smaller number of air channels 32 with one side having a greater number than the other side.

Each heater of the heating assembly 120 comprises a rectangular ceramic plate with an electrical heating element (not shown) embedded inside the ceramic plate. The electrical heating elements have a high electrical resistance and generate heat in response to an electric current flow. The ceramic plates, which are in contact with the consumable 10 during use, conduct heat from the heating elements and transfer the heat to the consumable 10 by conduction. The air in the cavity 108 is also heated. In this way, the heating assembly 120 and the cavity 108 form a heating oven for the tobacco in the consumable 10.

The heating element embedded in each ceramic plate is electrically connected to the controller 114, which controls the amount of electrical power flowing to each heater of the heating assembly 120 from the battery 118. Each heater of the heating assembly 120 is connected to the controller 114 to enable independent heating. In other words, the heating assembly is electrically connected to the controller 114 to enable the first planar heater 104 to have a different target heating temperature from the second planar heater 106 at any given time. In other embodiments, the heating elements can be provided on the ceramic plates. Alternatively, the first and second planar heaters 104, 106 may be other types of heater, such as non-ceramic metal heating plates.

The first and second planar heaters 104, 106 may, in other embodiments, be replaced with non-planar heaters, such as rod-shaped or curved film heaters.

Temperature sensors 107 are provided for each of the first planar heater 104 and the second planar heater 106 in the heating assembly 120. This can allow the controller 114 to ensure the temperature of each heater does not exceed a desired target heating temperature. The temperature sensors 107 can be embodied as a thermistor or thermocouple, for example. Alternatively, the controller 114 may be able to infer the temperature of each heater of the heating assembly 120 by tracking the amount of electrical power provided to each heater or the electrical resistance of each heater, in which case temperature sensors 107 may not be necessary.

The controller 114 controls the target heating temperature of the first planar heater 104 using a first temperature profile. The second planar heater 106 is controlled by the controller 114 using a second temperature profile, which is different from the first temperature profile. The first and second temperature profiles and the heating assembly 120 are configured specifically to heat but not bum the consumable 10 comprising tobacco. However, in other embodiments, other forms of aerosol forming substances may be used.

The heating assembly 120 may be provided with a hinge or other mechanism (not shown) that enables the first planar heater 104 and the second planar heater 106 to be moved apart so that the consumable 10 can be inserted more easily. The mechanism may be incorporated into a door of the housing 102, in one example. Alternatively, as described further below, the consumable 10 may be insertable through an opening in the mouthpiece 112.

Figure 4 shows a more detailed view of the consumable 10 according to an example embodiment.

The consumable 10 is a flat-shaped tobacco article having, for example, a flat cuboid shape extending along an article axis X and having external dimensions LxWxD. In a typical example, the length L of the consumable 10 according to the article axis X equals substantially to 33 mm while its width W and depth D are substantially equal respectively to 12 mm and 1 ,2 mm. According to different examples, the values L, W and D can be selected within a range of +/- 40%, for example. The depth D of the consumable 10 is formed by a pair of parallel walls 13A, 13B, called hereinafter narrow walls 13A, 13B, and the width W of the consumable 10 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 consumable 10 can have any other suitable flat shape and/or external dimensions. According to still other embodiments, the consumable 10 can present any other suitable shape, as for example a stick shape.

The consumable 10 comprises a substrate portion 15 and a mouthpiece portion 16 arranged along the article axis X. The substrate portion 15 may for example be slightly longer than the mouthpiece portion 16. For example, the length L2 of the substrate portion 15 according to the article axis X may be substantially equal to 18 mm and the length L1 of the mouthpiece portion 16 according to the article axis X may be substantially equal to 15 mm. The substrate portion 15 defines an abutting end 18 of the consumable 10 and the mouthpiece portion 16 defines a mouth end 20 of the consumable 10. The substrate portion 15 and the mouthpiece portion 16 may be fixed one to the other by a wrapper 21 extending around the substrate axis X. The wrapper 21 forms the narrow and wide walls 13A, 13B, 14A, 14B of the consumable 10. 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 means. 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 consumable 10 between the abutting end 18 and the mouth end 20.

The mouthpiece 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 corrugated paper, for example, as shown in Figure 4. The core 27 may be formed through an extrusion and/or rolling process into a stable shape. Advantageously, the core 27 is arranged inside the mouthpiece portion 16 to be entirely in contact with the internal surface of the wrapper 21 delimiting this mouthpiece portion 16.

In some example embodiments, the consumable 10 can have a total volume of 2118 or 554 mm³. The aerosol generating substance in the consumable 10 can comprise, by percentage of weight, 50% tobacco, 11.5% Propylene Glycol (PG), 20% Glycerin, 11.0% binder, 4.5% gum, and 3% water. The aerosol generating substance in the consumable 10 can have a weight of 200 mg. The aerosol generating substance can contain 3.07 mg of Nicotine.

Alternatively, the aerosol generating substance can have a weight of 275mg, contain 4.76 mg of Nicotine, 0.9 mg of PG, 44.5 mg of Glycerin, and can be in an elongated stick form.

The wrapper 21 can include a base paper of 0.13 mm thickness and a basis weight of 100 g/m². The wrapper 21 can include an aluminium foil of 0.006 mm thickness. The core 27 can comprise paper having 0.13 mm thickness and basis weight of 100 g/m².

Figure 5 shows an end view of the substrate portion 15. The substrate portion 15 comprises a vaporizable material for heating in the heating assembly 120. In this example, the vaporizable material comprises tobacco 30. The tobacco 30 is arranged within the wrapper 21 and has a corrugated shape so that a plurality of air channels 32 aligned with the substrate axis X are formed within the substrate portion 15. The air channels 32 allow air to be drawn through the consumable 10 during use so that generated aerosol can be drawn from the cavity 108 more easily.

A more detailed depiction of the aerosol generating device 100 is shown in Figures 6 and 7.

The aerosol generating device 100 comprises a housing 102 extending along a device axis Y and a mouthpiece 112. According to the example described below, the mouthpiece 112 and the housing 102 form two different pieces. Particularly, according to this example, the mouthpiece 112 is designed to be fixed on a fixing end of the housing 102.

As shown in Figure 7, the mouthpiece 112 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 housing 102 when the mouthpiece 112 is fixed on a fixing end of the housing 102. For example, the peripheral part 44 can be designed to cooperate with a gasket 45 arranged on the fixing end of the housing 102 in order to seal the space formed between the peripheral part 44 and the external surface of the housing 102. The peripheral part 44 also has an intermediate portion extending for example transversally to the device axis Y and forming a transition between the central part 43 of the mouthpiece 112 and the collar defined by the peripheral part 44. The central part 43 of the mouthpiece 112 defines a through hole 46 adapted to receive at least partially the consumable 10. Particularly, the through hole 46 can be adapted to receive at least a part of the mouthpiece portion 16 of the consumable 10, as shown in Figure 7. Advantageously, the through hole 46 can be adapted to fit tightly the mouthpiece portion 16 of the consumable 10 so as to avoid or minimise flow leakage between a wall delimiting the through hole 46 and an external surface of the consumable 10. In some embodiments, the consumable 10 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 consumable 10 inside the through hole 46.

As shown in Figure 7, an inner volume 47 is formed between an inner surface 48 of the mouthpiece 112 and the fixing end of the housing 102. This inner volume 47 is crossed by the consumable 10 when it is inserted inside the housing 102. For example, the consumable 10 can divide the inner volume 47 in two symmetric parts.

The housing 102 delimits an internal space of the aerosol generating device 100 receiving various elements designed to carry out different functionalities of the aerosol generating device 100. This internal space can, for example, receive the battery 118 and controller 114. The internal space also comprises a heating chamber 50 containing the heating assembly 120 for heating the substrate portion 15 of the consumable 10.

As shown in this Figure 7, the heating chamber 50 can form a cup shape adapted to receive at least the substrate portion 15 of the consumable 10 and, in some cases, at least a part of the mouthpiece portion 16. The heating chamber 50 may form a cuboid shape, similar to the consumable 10, extending along the device axis Y and comprising a pair of parallel narrow walls extending along the device axis Y, a pair of parallel wide walls 54A, 54B extending also along the device axis Y and a bottom wall 58 adjacent to each of said walls and extending perpendicularly to the device axis Y. The bottom wall 58 forms a closed end of the chamber 50. Opposite to the bottom wall 58, the heating chamber 50 defines an opening 60 configured to receive the consumable 10 so that the corresponding wide walls 14A, 14B of the consumable 10 face the corresponding wide walls 54A, 54B of the heating chamber 50 and the corresponding narrow walls 13A, 13B of the consumable 10 face the corresponding narrow walls of the heating chamber 50 and the abutting end 18 of the consumable 10 abuts against the bottom wall 58 or at least a rib extending from this bottom wall 58. Alternatively, the abutting end 18 faces the bottom wall 58 without being in contact with it. The heating chamber 50 is thus configured to receive the consumable 10 so that the narrow walls 13A, 13B of the consumable 10 face the narrow walls of the heating chamber 50, and the wide wall 14A (respectfully 14B) of the consumable 10 faces the wide wall 54B (respectfully 54A) of the heating chamber 50. The facing wide walls 14A, 14B, 54A, 54B and the facing narrow walls can be in contact one with the other or spaced one from the other. In this way, the heating chamber 50 provides the cavity 108 for receiving the consumable 10, as discussed previously.

The heating chamber 50 further comprises the first planar heater 104 and the second planar heater 106, which are arranged in the heating chamber 50 to heat the substrate portion 15 of the consumable 10. In the example embodiment of Figure 7, the first planar heater 104 and the second planar heater 106 are arranged on the inner faces of the wide walls 54A, 54B, with the intervening space between the first and second planar heaters 104, 106 forming the cavity 108. The first and second planar heaters 104, 106 can have other arrangements within the heating chamber 50 in other example embodiments.

An airflow channel extending from an air inlet 110 until the closed end of the heating chamber 50 is formed inside the aerosol generating device 100. Thus, air can enter the heating chamber 50 through the airflow channel and pass first to the substrate portion 15 and then through the mouthpiece portion 16 of the consumable 10 before being delivered to the user. The air inlet 110 is shown positioned on the housing 102 in Figure 1 ; however, in other embodiments the air inlet 110 can also be arranged in or on the mouthpiece 112. Specifically, the air inlet can be arranged in the intermediate portion of the peripheral part 44 of the mouthpiece 112. The air inlet 110 can be formed by a through hole.

An example use of the aerosol generating device 100 will now be described.

In use, a user inserts the consumable 10 into the cavity 108 and presses the button 116 to initiate aerosol generation, or, in other words, initiate a vaping session. The controller 114 then sets a sequence of target heating temperatures for the first planar heater 104 using the first temperature profile over the course of the session.

In this example embodiment, the controller 114 implements each target heating temperature in the first temperature profile by varying the duty cycle of the first planar heater 104 to a corresponding value, so that more or less power is delivered to the first planar heater 104. In general, the controller 114 is able to change the target heating temperature near-instantaneously, whereas the first planar heater 104 changes temperature more gradually. The controller 114 may receive feedback from one of the temperature sensors 107 to ensure the first planar heater 104 does not exceed the current target heating temperature. The controller 114 may turn off the first planar heater 104 completely if the current target heating temperature is exceeded, until the temperature drops to a value below a threshold based on the target heating temperature. Alternatively, the duty cycle of the first planar heater 104 may be lowered. Similarly, the controller 114 may increase the amount of power to the first planar heater 104 if the first planar heater 104 drops below a threshold temperature based on the current target heating temperature.

At the same time, the controller 114 instructs the second planar heater 106 to operate in the same manner using the second temperature profile, which also comprises a plurality of target heating temperatures. A vaping session may have a pre-defined duration, such as about 5 minutes, and the first heating and second temperature profiles each have a total duration equal to the duration of the vaping session. The first and second temperature profiles are initiated simultaneously by the controller 114 and have the same total duration. However, in other embodiments, the first and second temperature profiles may have different durations and the controller 114 may initiate the first and second temperature profiles at different times. However, in any case, the first temperature profile always has a higher target heating temperature than the second temperature profile.

The consumable 10 in the cavity 108 then generates an aerosol in response to the heat delivered by the heating assembly 120 during the vaping session. The user inhales through the air outlet 113 on the mouthpiece 112, causing air to flow through the air inlet 110 and the cavity 108 towards the mouthpiece 112. This carries the generated aerosol to the user to enjoy. Once the session is finished, the consumable 10 is expended and can be removed from the aerosol generating device 100 by the user.

Advantageously, at any time during the vaping session, the first temperature profile has a higher target heating temperature than the second temperature profile. As shown in Figure 3, the first planar heater 104 is in contact with the side of the consumable having a lower surface area. By operating the first planar heater 104 using higher target heating temperatures, underheating of the lower side (as viewed in Figure 3) of the consumable 10, which could otherwise be caused by this side’s lower surface area in contact with the first planar heater 104, is avoided. Thus, the consumable 10 is heated more evenly and a higher quality aerosol can be produced. The aerosol generating device 100 and/or the consumable 10 may comprise a visual marking indicating the correct way in which to insert the consumable 10 into the cavity 108 so that the correct sides is exposed to higher temperatures in use.

Additionally, the button 116 is positioned on the second external surface 102b so that the user is prompted to hold the aerosol generating device 100 so that the button 116 can be pressed with an index finger in an overhand grip. This generally leads to the user being in contact mainly with the second external surface 102b. The second planar heater 106 is positioned adjacent the second external surface 102b and the first planar heater 104 is positioned away from the second external surface 102b. Thus, the first planar heater 104, which is hotter during use, is moved away from the point of greatest contact with the user, reducing the temperature of the second external surface 102b. This reduces the risk of a hotspot on the housing 102 at the point of greatest contact with the user.

More aerosol (or “vapour”) is, in general, generated at a given point in time depending on the actual temperatures of the first and second planar heaters 104, 106. More or less energy is consumed by the heating apparatus 120 depending on the target heating temperatures used at a given point during the session. Advantageously, in some embodiments the first and second temperature profiles can comprise one or more transitions to lower target heating temperature. Following a transition, the actual temperature of the first or second planar heater 104, 106 drops gradually towards the lower target heating temperature. This gradual drop means that a higher level of vapour generation can be prolonged while at the same time enacting a lower target heating temperature for the first planar heater 104, thereby reducing energy usage. The first and second planar heaters 104, 106 comprise ceramic and, consequently, are able to retain their temperature for longer following a drop in target heating temperature, compared to some other materials often used for heaters, such as metal. This provides a particularly effective profile for planar ceramic planar heaters heating tobacco.

Figure 8 shows a graph plotting an example first temperature profile 200 and an example second temperature profile 210 according to an embodiment of the invention.

The first temperature profile 200 comprises a plurality of target heating temperatures including a first, second, third, and fourth target heating temperature 202, 204, 206, 208, referred to hereafter as “temperatures” for brevity. The second temperature profile 210 comprises a plurality of target heating temperatures including a first, second, third, and fourth target heating temperature 212, 214, 216, 218, also referred to hereafter as “temperatures” for brevity. Times t0-t7 shown in Figure 8 denote transitions between target heating temperatures.

The first temperature profile 200 begins at the first (and initial) temperature 202 and drops to the second temperature 204 at time t1. In this example, the first temperature 202 is the maximum temperature of the first temperature profile 200. At time t4, the first temperature profile 200 drops to the third temperature 206, which is the minimum temperature of the first temperature profile 200, before rising to the fourth (and final) temperature 208 at time t6. The first temperature profile 200 ends at time t7. The second temperature profile 210 begins at the first (and initial) temperature 212 and drops to the second temperature 214 at time t2. In this example, the first temperature 212 is the maximum temperature of the second temperature profile 210. At time t3, the second temperature profile 210 drops to the third temperature 216 before dropping to the fourth and final temperature 218 at time t5. The fourth temperature 218 is also the minimum temperature of the second temperature profile 218. The second temperature profile 210 ends at time t7.

The first temperature profile 200 always has a higher target heating temperature compared to the second temperature profile 210. This enables more even heating of the consumable 10 during use. Additionally, in some embodiments the aerosol generating device 100 is configured to be held in a particular orientation so that the user has a lower amount of surface area in contact with the external surface of the aerosol generating device 100 adjacent the planar heater operating the first heating profile 200. This avoids introducing a hotspot on the external surface of the aerosol generating device at the point of most contact with the user.

Table 1 shows the temperature values for each target heating temperature in the specific example of the first temperature profile 200 and the second temperature profile 210.

Table 1 : example target heating temperatures for the first temperature profile 200 and the second temperature profile 210.

Table 2 (left two columns) shows the values of times t0-t7 in the specific example of Figure 8. Table 2 (right two columns) shows the example durations that have been used in the first and second temperature profiles 200, 210.

Table 2: The two leftmost columns show the specific values of times t0-t7 used in the example profiles of Figure 8. The two rightmost columns show the example periods that have been used in the first temperature profile 200 and the second temperature profile 210. The second temperature profile 210 decreases progressively to lower target heating temperatures at each transition over the course of the session. This allows the second temperature profile 210 to benefit from temperature coasting. The maximum temperature 212 of the second temperature profile 210 is greater than the minimum temperature 206 of the first temperature profile 200. The largest temperature difference between the first and second temperature profiles 200, 210 occurs at the end of each profile, i.e. at time t7. The first temperature profile 200 comprises at least one decrease and at least one increase, in order to make use of temperature coasting. The increase occurs after the decrease and results in no net change in target heating temperature.

Over a vaping session, the consumable 10 loses mass, may expand and contract in line with the associated heating and mass loss, and, consequently, undergoes changes in material properties (e.g., specific heat, density, thermal conductivity). It has been found that the above-described features of the first and second temperature profiles 200, 210 are particularly effective for accounting for these issues in the heating apparatus of Figure 3.

The features of the first and second temperature profiles 200, 210 described above may be implemented using values other than those shown in Figure 8 and Tables 1 and 2. In particular, the timing and target heating temperature values used may be selected to optimise use of the aerosol generating device 100 with tobacco as the aerosol generating substance. For example, the maximum temperatures 202, 212 may be selected for being below the combustion temperature of tobacco and at or above temperatures known to generate a large quantity of vapour from tobacco to maximise the user experience.

As described previously, the first temperature profile 200 comprises a transition from temperature 204 to the lower temperature 206. The durations of periods tO- t1 and t4-t6 and temperatures 204, 206 are such that the total area under the first temperature profile 200 is less compared to a flat profile of 250°C. This reduces the energy consumption of operating the first planar heater 104 because the target heating temperature is proportional to, or at least correlates with, power consumption. Due to the lag in actual temperature of the first planar heater 104, a prolonged period of higher vapour volume is maintained in the period t4-t6, despite the lower energy expenditure.

Similarly, the successive transitions to lower target heating temperatures of the second temperature profile 200 provides the second temperature profile 210 with a total area under the second temperature profile 210 that is less than a flat temperature profile of 230 °C. The second temperature profile 210 can effectively temperature coast in the period t2-t7 for improved efficiency and while prolonging higher vapour generation.

Claims

1. An aerosol generating device configured to generate an aerosol for inhalation by a user, comprising: a first heater and a second heater controllable independently from the first heater, each configured to heat an aerosol forming substance to generate an aerosol; a cavity provided between the first heater and the second heater, configured to receive the aerosol forming substance; and a controller configured to operate the first heater and the second heater by setting target heating temperatures for the first heater and the second heater using a first temperature profile and a second temperature profile, respectively; wherein, at all times during the first temperature profile or the second temperature profile, the target heating temperature of the first temperature profile is higher than the target heating temperature of the second temperature profile; wherein the first heater and the second heater are substantially planar and arranged to heat two different surfaces of a consumable.

2. The aerosol generating device of claim 1 , wherein the first temperature profile comprises an initial target heating temperature, a final target heating temperature, a maximum target heating temperature and a minimum target heating temperature; and wherein the second temperature profile comprises an initial target heating temperature, a final target heating temperature, a maximum target heating temperature and a minimum target heating temperature.

3. The aerosol generating device of claim 2, wherein the initial target heating temperature of the first temperature profile is equal to the maximum target heating temperature of the first temperature profile.

4. The aerosol generating device of claim 2 or claim 3, wherein the second temperature profile comprises a plurality of target heating temperatures that decrease progressively from the initial to the final target heating temperature of the second temperature profile.

5. The aerosol generating device of claims 2 to 4, wherein the maximum target heating temperature of the second temperature profile is greater than the minimum target heating temperature of the first temperature profile.

6. The aerosol generating device of claims 2 to 5, wherein the difference between the initial target heating temperature of the first temperature profile and the initial target heating temperature of the second temperature profile is less than the difference between the final target heating temperature of the first temperature profile and the final target heating temperature of the second temperature profile.

7. The aerosol generating device of claims 2 to 6, wherein the difference in target heating temperatures between the first temperature profile and the second temperature profile is greatest at the end of the first and second temperature profiles compared to any other time during the first or second temperature profiles.

8. The aerosol generating device of claims 2 to 7, wherein the first temperature profile comprises at least one decrease and at least one increase in target heating temperature.

9. The aerosol generating device of claim 8, wherein the increase occurs after the decrease.

10. The aerosol generating device of claim 9, wherein the target heating temperature before the decrease is equal to the target heating temperature after the increase.

11. The aerosol generating device of any of the preceding claims, wherein the first heater is positioned adjacent a first external surface of the aerosol generating device, the second heater is positioned adjacent a second external surface of the aerosol generating device, and the aerosol generating device is configured to be held in use preferentially with the second external surface having a greater surface area in contact with a user than the first external surface.

12. The aerosol generating device of any of the preceding claims, wherein the first heater and/or the second heater comprise ceramic.

13. A method of operating an aerosol generating device comprising a first heater and a second heater controllable independently from the first heater, comprising: operating the first heater and the second heater by setting target heating temperatures for the first heater and the second heater using a first temperature profile and a second temperature profile, respectively; wherein, at all times during the first temperature profile or the second temperature profile, the target heating temperature of the first temperature profile is higher than the target heating temperature of the second temperature profile; wherein the first heater and the second heater are substantially planar and arranged to heat two different surfaces of a consumable.

14. A non-transitory computer readable medium comprising executable instructions that, when executed by a processor on an aerosol generating device comprising a first heater and a second heater controllable independently from the first heater, cause the aerosol generating device to perform steps comprising: operating the first heater and the second heater by setting target heating temperatures for the first heater and the second heater using a first temperature profile and a second temperature profile, respectively; wherein, at all times during the first temperature profile or the second temperature profile, the target heating temperature of the first temperature profile is higher than the target heating temperature of the second temperature profile; wherein the first heater and the second heater are substantially planar and arranged to heat two different surfaces of a consumable.