Aerosol-generating device with wet expanding material

Abstract

The invention relates to an aerosol-generating device that comprises a cavity for receiving an aerosol-forming substrate. The aerosol-generating device comprises a major airflow channel extending from an air inlet to an air outlet via the cavity of the device and comprises a resistance-to-draw modifying mechanism comprising a wet expanding material. The wet expanding material is in fluid connection with ambient air. The wet expanding material is configured to expand its volume if in contact with water comprised in the ambient air. The device is configured such that a cross-sectional area of the major airflow channel is at least partly reduced as a result of an expansion of the wet expanding material. The invention further relates to an aerosol-generating system comprising the aerosol-generating device and an article comprising an aerosol-forming substrate.

Description

[0001] AEROSOL-GENERATING DEVICE WITH WET EXPANDING MATERIAL

[0002] The present disclosure relates to an aerosol-generating device. The present disclosure further relates to an aerosol-generating system comprising an aerosol-generating device and an article comprising an aerosol-forming substrate.

[0003] It is known to provide an aerosol-generating device for generating an inhalable vapor. Such devices may heat an aerosol-forming substrate contained in an aerosol-generating article without burning the aerosol-forming substrate. The aerosol-generating article may have a rod shape for insertion of the aerosol-generating article into a heating chamber of the aerosol-generating device. A heating element is typically arranged in or around the heating chamber for heating the aerosol-forming substrate, once the aerosol-generating article is inserted into the heating chamber of the aerosol-generating device.

[0004] Ambient conditions may influence the quality of the generated aerosol. Particularly high humidity conditions may lead to the aerosol-forming substrate having a high humidity. Particularly low humidity conditions may lead to the aerosol-forming substrate having a low humidity. An aerosol-forming substrate having a high humidity may lead to a “warm aerosol perception” effect, also known as “hot aerosol effect”, when the vaporized humidity in the aerosol-forming substrate is inhaled during the first puff. Particularly in humid environments, an undesirable warm first puff may be created due to a high moisture content in the aerosolforming substrate of the aerosol-generating article.

[0005] It would be desirable to have an aerosol-generating device with improved aerosol consistency. It would be desirable to have an aerosol-generating device for reducing or preventing the “hot aerosol effect”. It would be desirable to have an aerosol-generating device with reduced humidity in the first generated aerosol puff. It would be desirable to have an aerosol-generating device preventing an undesirable warm first puff in humid environments.

[0006] According to an embodiment of the invention there is provided an aerosol-generating device that may comprise a cavity for receiving an aerosol-forming substrate. The aerosolgenerating device may comprise a major airflow channel extending from an air inlet to an air outlet via the cavity of the device. The aerosol-generating device may comprise a resistance- to-draw modifying mechanism. The resistance-to-draw modifying mechanism may comprise a wet expanding material. The wet expanding material may be in fluid connection with ambient air. The wet expanding material may be configured to expand its volume if in contact with water comprised in the ambient air. The device may be configured such that a cross- sectional area of the major airflow channel is at least partly reduced as a result of an expansion of the wet expanding material. According to an embodiment of the invention there is provided an aerosol-generating device that comprises a cavity for receiving an aerosol-forming substrate. The aerosolgenerating device comprises a major airflow channel extending from an air inlet to an air outlet via the cavity of the device. The aerosol-generating device comprises a resistance-to- draw modifying mechanism. The resistance-to-draw modifying mechanism comprises a wet expanding material. The wet expanding material is in fluid connection with ambient air. The wet expanding material is configured to expand its volume if in contact with water comprised in the ambient air. The aerosol-generating device is configured such that a cross-sectional area of the major airflow channel is at least partly reduced as a result of an expansion of the wet expanding material.

[0007] By the aerosol-generating device according to the invention, an aerosol-generating device with improved aerosol consistency may be provided. By the aerosol-generating device of the invention, an aerosol-generating device for reducing or preventing the “hot aerosol effect” may be provided. By the aerosol-generating device according to the invention, an aerosol-generating device with reduced humidity in the first generated aerosol puff may be provided. By the aerosol-generating device according to the invention, an aerosolgenerating device preventing an undesirable warm first puff in humid environments may be provided. By the aerosol-generating device according to the invention, an aerosol-generating device that automatically adjusts the air intake that is heated by the device to the humidity level of the environment may be provided.

[0008] By means of the resistance-to-draw modifying mechanism, the airflow within the device may be regulated or controlled based on the humidity of the environment. By reducing the cross-sectional area of the major airflow channel, the resistance-to-draw modifying mechanism may influence the speed, pressure, or distribution of the airflow. For example, the amount of airflow through the cavity may be reduced in humid environments, thereby avoiding the hot aerosol effect. The resistance-to-draw modifying mechanism may utilize the expansion properties of the wet expanding material to actively control or modulate the cross- sectional area of the major airflow channel. This may allow for customization and optimization of the airflow characteristics within the system.

[0009] As used herein, the term “wet expanding material” refers to a substance or mixture that has the ability to increase in volume or size when exposed to moisture or water. The wet expanding material may undergo a physical or chemical change when it comes into contact with water, resulting in expansion or swelling. This expansion may occur due to various mechanisms, such as absorption of water molecules, the formation of gels or foams, or chemical reactions that generate gas or vapors. The wet expanding material may be one or more of a polymer, a gel, a hydrogel, a foam, and minerals. The wet expanding material may be configured such that the expansion is irreversible. The wet expanding material may be configured such that the expansion is reversible. The wet expanding material may be configured such that its volume increases when being exposed to a high humidity environment and, afterwards, decreases again when being subsequently exposed to a low humidity environment.

[0010] The degree of expansion may vary depending on factors such as the amount of water absorbed, temperature, and the specific chemical reactions or physical processes involved.

[0011] As used herein, the term "in fluid connection" refers to a state where the wet expanding material and ambient air are linked together in a manner that allows the flow of fluid between them. It implies that there is a pathway or conduit established to enable the transfer of ambient air to the wet expanding material.

[0012] As used herein, the term “cross-sectional area” refers to the measure of the two- dimensional extent or area of a shape or object when it is cut perpendicular to a specific plane. It represents the area of the shape or object as seen from the direction of the cut.

[0013] Accordingly, when an object or structure is cut across or sliced through, the resulting shape or surface that is exposed is called a “cross-section”. The cross-sectional area is the area of this resulting shape when viewed from the cut plane.

[0014] As used herein, the term “cross-sectional area of the major airflow channel” refers to the total cross-sectional area of the inner space of the major airflow channel that allows the airflow to pass therethrough. The cross-sectional area of the major airflow channel generally extends in a direction perpendicular to a principal flow axis of the airflow. When it is referred herein to “the cross-sectional area of the major airflow channel being at least partly reduced as a result of an expansion of the wet expanding material”, this means that the cross- sectional area of the major airflow channel, at a certain position or interval between the upstream end and the downstream end, changes to become smaller caused by the expansion of the wet expanding material.

[0015] The expansion of a wet expanding material refers to the increase in volume or size that occurs when the material absorbs moisture or comes into contact with water.

[0016] The aerosol-generating device may be configured such that the cross-sectional area of the major airflow channel is at least partly reduced at a position upstream of the cavity as a result of an expansion of the wet expanding material. The aerosol-generating device may be configured such that the cross-sectional area of the major airflow channel measured at a position of the major airflow channel upstream of the cavity is at least partly reduced as a result of an expansion of the wet expanding material. The wet expanding material may be attached to an inner wall of the major airflow channel. The wet expanding material may be attached to an inner wall of the major airflow channel by means of an adhesive. The wet expanding material may be attached to an inner wall of the major airflow channel by means of a form-fit. The wet expanding material may be attached to an inner wall of the major airflow channel by means of a friction-fit.

[0017] A portion of the inner wall of the major airflow channel may comprise a recess. The wet expanding material may be at least partly arranged within the recess.

[0018] The major airflow channel may comprise a plurality of, at least partially, spatially separated air channel portions which are arranged in parallel with respect to the airflow through the major airflow channel. The cross-sectional area of the major airflow channel may be a total cross-sectional area of the major airflow channel given by the sum of the cross- sectional areas of the plurality of the air channel portions.

[0019] The major airflow channel may comprise a first air channel portion and a second air channel portion which are arranged in parallel with respect to the airflow, and which are at least partially spatially separated. The first air channel portion may comprise a first cross- sectional area. The second air channel portion may comprise a second cross-sectional area. The total cross-sectional area of the major airflow channel may be the sum of the first cross- sectional area and the second cross-sectional area.

[0020] The resistance-to-draw modifying mechanism may be configured such that only one of the first and second cross-sectional areas is at least partly reduced as a result of an expansion of the wet expanding material.

[0021] The first air channel portion may surround the second air channel portion. The first air channel portion may coaxially surround the second air channel portion. The second air channel portion may be confined by a tubular element. The tubular element may be disposed in the first air channel portion.

[0022] The wet expanding material may be attached to an inner wall of the first air channel portion. The wet expanding material may be attached to an inner wall of the second air channel portion.

[0023] One or both of the first and second air channel portions may be at least partly tubular.

[0024] The resistance-to-draw modifying mechanism may comprise an air communication channel comprising a separate air inlet. The wet expanding material may be provided in the air communication channel. Thereby, it may be avoided that the wet expanding material is located within the major airflow channel.

[0025] The air communication channel may extend from a separate air inlet to a chamber. The chamber of the air communication channel may accommodate the wet expanding material. The air communication channel may serve as a means of connecting the separate air inlet to the designated chamber, facilitating the movement of air between them. It may take various forms, such as ductwork, piping, or other types of conduits, depending on the specific system or application.

[0026] Within the aerosol-generating device, the chamber of the air communication channel may be fluidly isolated from the cavity. Within the aerosol-generating device, the air communication channel may be fluidly isolated from the cavity. Within the aerosol-generating device, the air communication channel may be fluidly isolated from the major airflow channel.

[0027] It is understood that "fluidly isolated" from the major airflow channel means that there is a barrier or separation between the two. This barrier prevents the direct flow of air between the major airflow channel and the chamber. As a result, air movement or exchange between the two spaces is restricted or limited, at least except for an exchange via the ambient environment outside of the device.

[0028] The fluid isolation may be achieved through various means, such as the use of valves, gates, doors, partitions, or physical barriers that prevent the free flow of air between the major airflow channel and the chamber.

[0029] The resistance-to-draw modifying mechanism may comprise a transmission means. The transmission means may be configured to at least partly reduce the cross-sectional area of the major airflow channel as a result of an expansion of the wet expanding material. The transmission means may be particularly preferable for embodiments where the wet expanding material is not provided within the major airflow channel, for example where the wet expanding material is provided in the chamber of the air communication channel.

[0030] The transmission means refers to a mechanism or system that is adapted to partially decrease the available cross-sectional area of the major airflow channel when the wet expanding material expands due to an increase in the humidity of the environment.

[0031] The transmission means, which may be a mechanical or structural component, is specifically adapted to respond to the expansion of the wet expanding material. When the wet expanding material absorbs moisture and expands, the transmission means may adjust or modify the cross-sectional area of the major airflow channel, reducing its size to some extent.

[0032] The exact mechanism employed to achieve this reduction in cross-sectional area may vary depending on the specific design. It may involve the use of movable parts, adjustable structures, or other means of modifying the shape or dimensions of the channel.

[0033] The transmission means may comprise a lever arrangement or a tap-like rotation arrangement.

[0034] The transmission means may comprise a lever arrangement. A lever arrangement may refer to the configuration or setup of one or more levers in a system or mechanism. A lever may be a configuration consisting of a rigid bar or beam that pivots around a fixed point called a fulcrum. The lever arrangement may describe how the levers are positioned and interconnected within a system to achieve a specific mechanical advantage or function.

[0035] The lever arrangement may comprise a small arm, a long arm, a lever axis, and a hatch.

[0036] The resistance-to-draw modifying mechanism may be configured such that an expansion of the wet expanding material causes a movement of the small arm which, in turn, causes the long arm to rotate around the lever axis, such that the hatch moves inside the major airflow channel to at least partly reduce the cross-sectional area of the major airflow channel.

[0037] By utilizing the wet expanding material and the lever system, the resistance-to-draw modifying mechanism may allow for adjustable resistance-to-draw within the major airflow channel. As the wet expanding material expands, it may trigger the movement of the lever system, which in turn controls the position of the hatch. A precise regulation of the airflow resistance may be provided. Customization and optimization of the airflow conditions within the channel may be allowed.

[0038] Further advantages of this mechanism may include a dynamic response. The mechanism may respond dynamically to changes in the wet expanding material. When the wet expanding material expands due to moisture absorption, it may trigger the movement of the lever system, causing the hatch to move and reduce the cross-sectional area of the major airflow channel. This dynamic response may ensure that the resistance-to-draw and airflow characteristics may be actively adjusted in real-time, adapting to varying conditions or requirements.

[0039] Further advantages of this mechanism may include an efficient airflow control. It may allow for precise modulation of the airflow speed, pressure, or distribution, optimizing the performance and functionality of the overall system or device. This may be particularly useful in applications where precise control of ventilation, air quality, or pressure levels is required.

[0040] Further advantages of this mechanism may include an adaptive functionality. The resistance-to-draw modifying mechanism may adapt to changes in the wet expanding material. As the wet expanding material expands or contracts based on the moisture content, the lever system and hatch may respond accordingly, actively modifying the cross-sectional area of the major airflow channel. This adaptability may ensure that the mechanism may maintain optimal airflow conditions regardless of variations in the wet expanding material properties. By utilizing the wet expanding material and lever system, it may enable precise regulation and optimization of the airflow conditions within the major airflow channel, enhancing the overall performance and functionality of the system or device.

[0041] The resistance-to-draw modifying mechanism may comprise a spring element configured to push onto the wet expanding material. The pushing spring element may help to bring an expanded wet expanding material back into the unexpanded state, when the device is relocated from a high humidity environment into a low humidity environment.

[0042] The resistance-to-draw modifying mechanism may comprise a spring element configured to push directly onto the wet expanding material. The resistance-to-draw modifying mechanism may comprise a spring element configured to push onto the wet expanding material via an intermediary component.

[0043] The resistance-to-draw modifying mechanism may comprise a spring element configured to push a portion of the lever arrangement onto the wet expanding material.

[0044] The presence of a spring element may allow for increased responsiveness and sensitivity of the mechanism. When the wet expanding material expands, the spring element may exert pressure on the lever arrangement, facilitating a quick and immediate response. This may ensure that the resistance-to-draw modification occurs promptly and accurately in direct relation to the expansion of the wet expanding material.

[0045] A further advantage of a spring element may be a precise adjustment. The spring element may provide a means for fine-tuning the resistance-to-draw modification. By adjusting the characteristics of the spring, such as its stiffness or compression, the amount of force exerted on the lever arrangement may be controlled. This precise adjustment may enable fine regulation of the resistance within the system, allowing for customized airflow control according to specific requirements or conditions.

[0046] A further advantage of a spring element may be a reliable and consistent performance. The incorporation of a spring element may add reliability and consistency to the resistance-to-draw modifying mechanism. Springs are known for their predictable and consistent behaviour, providing a stable and repeatable force. This may ensure that the mechanism consistently responds to the expansion of the wet expanding material, maintaining the desired level of resistance and airflow control over multiple cycles or under varying conditions.

[0047] Accordingly, the spring element may offer versatility in accommodating different variations of the wet expanding material. By adjusting the spring characteristics, the mechanism may adapt to variations in the expansion properties of the wet expanding material, ensuring reliable operation regardless of moisture levels or material differences. This versatility may allow the mechanism to be applied to various systems or devices that utilize different types of wet expanding materials.

[0048] Furthermore, springs are known for their durability and longevity. They may withstand repeated cycles of compression and decompression without significant wear or degradation. Incorporating a spring element in the resistance-to-draw modifying mechanism may contribute to its durability and reduces the need for frequent maintenance or replacement, resulting in a more reliable and cost-effective system.

[0049] The wet expanding material may comprise one or more of a Super Absorbent Polymer (SAP), a water swellable elastomer, a silica gel, calcium chloride, wood, and a cellulose with low degree of acetylation.

[0050] The wet expanding material may comprise a Super Absorbent Polymer (SAP) selected from one or more of sodium polyacrylate, polyacrylamide, and starch-based polymers.

[0051] The wet expanding material may comprise a cellulose with low degree of acetylation. The cellulose with low degree of acetylation may be cotton.

[0052] The wet expanding material may comprise a water swellable elastomer. The water swellable elastomer may be selected from polyurethane elastomers, styrene-butadiene rubber (SBR), ethylene propylene diene monomer (EPDM), natural rubber, nitrile rubber, silicone rubber, chloroprene rubber, and fluoroelastomers.

[0053] The wet expanding material may form an integral piece together with at least one substrate which does not significantly expand when in contact with water.

[0054] The advantages of a wet expanding material that forms an integral piece with at least one substrate that does not significantly expand when in contact with water may include controlled expansion. The wet expanding material, when exposed to water or moisture, may undergo expansion while remaining firmly bonded to the substrate that does not significantly expand. This may allow for controlled and predictable expansion behavior of the wet expanding material. By combining it with a substrate that maintains its dimensional stability, the overall expansion process may be more precisely controlled, ensuring consistent and reliable performance.

[0055] The integration of the wet expanding material with a non-expanding substrate may help to maintain the structural integrity of the material system. The substrate may provide stability and support, preventing excessive deformation or warping that could occur if the wet expanding material were to expand freely. This may ensure that the material system retains its shape, strength, and overall functionality, even during expansion and contraction cycles.

[0056] Further advantages may be improved handling and processing. The combination of the wet expanding material and the non-expanding substrate may simplify the handling and processing of the material system. The substrate may provide a solid base or framework, making it easier to work with the material during fabrication, installation, or assembly. It may enhance the material's rigidity and stability, facilitating precise shaping, cutting, or forming operations. This may simplify manufacturing processes and improves overall product quality and consistency.

[0057] A further advantage may be versatility in application. The integration of a wet expanding material with a non-expanding substrate may offer versatility in application. The wet expanding material may be selected based on its desired properties, such as its expansion rate, moisture absorption characteristics, or sealing capabilities.

[0058] A further advantage may be enhanced durability. The use of a non-expanding substrate alongside the wet expanding material may contribute to the overall durability and longevity of the material system. The substrate may provide mechanical strength and protection, helping to shield the wet expanding material from external stresses, impacts, or environmental factors. This may improve the material system's resistance to wear, tear, and degradation, ensuring long-term performance and reliability.

[0059] The wet expanding material may be provided on an inner wall of the major airflow channel. The wet expanding material provided on the inner wall of the major airflow channel may occupy between 5 percent and 50 percent, preferably between 10 percent and 40 percent, more preferably between 10 percent and 35 percent, more preferably between 10 percent and 30 percent, more preferably between 10 percent and 20 percent of the cross- sectional area surrounded by the inner wall of the major airflow channel.

[0060] The resistance-to-draw modifying mechanism may be configured to reduce the cross- sectional area of the major airflow channel as a result of an expansion of the wet expanding material by between 5 percent and 50 percent, preferably between 10 percent and 40 percent, more preferably between 15 percent and 35 percent. The resistance-to-draw modifying mechanism may be configured to reduce the cross-sectional area of the major airflow channel at a position upstream of the cavity as a result of an expansion of the wet expanding material by between 5 percent and 50 percent, preferably between 10 percent and 40 percent, more preferably between 15 percent and 35 percent.

[0061] The resistance-to-draw modifying mechanism may be configured such that the cross- sectional area of the at least a portion of the major airflow channel is reduced by at least 5 percent, preferably at least 10 percent, more preferably at least 15 percent in an ambient environment with a relative humidity of 100 percent at 20 degrees Celsius in comparison to an ambient environment with a relative humidity of 50 percent at 20 degrees Celsius.

[0062] The resistance-to-draw modifying mechanism may be configured such that the cross- sectional area of the at least a portion of the major airflow channel is reduced by at least 5 percent, preferably at least 10 percent, more preferably at least 15 percent in an ambient environment with a relative humidity of 70 percent at 30 degrees Celsius in comparison to an ambient environment with a relative humidity of 20 percent at 20 degrees Celsius.

[0063] The wet expanding material may be configured such that a volume of the wet expanding material increases by at least 10 percent, preferably at least 15 percent, more preferably at least 20 percent, more preferably at least 25 percent, more preferably at least 30 percent, more preferably at least 35 percent, more preferably 40 percent, more preferably at least 50 percent as a result of an increase in relative humidity of 50 percent at 20 degrees Celsius.

[0064] The resistance-to-draw modifying mechanism may be configured to reduce the resistance-to-draw of the major airflow channel by at least 5 percent, preferably by at least 10 percent, more preferably by at least 15 percent, more preferably by at least 20 percent as a result of the expansion of the wet expanding material.

[0065] The resistance-to-draw modifying mechanism may be configured to reduce the resistance-to-draw of the major airflow channel upstream of the cavity by at least 5 percent, preferably by at least 10 percent, more preferably by at least 15 percent, more preferably by at least 20 percent as a result of the expansion of the wet expanding material.

[0066] A cross-section of the major airflow channel may be at least partly circular shaped.

[0067] The aerosol-generating device may comprise a heater assembly configured for heating an aerosol-forming substrate arranged in the cavity. The heater assembly may comprise one or more heating elements configured for heating an aerosol-forming substrate arranged in the cavity. The aerosol-generating device may comprise one or more heating elements configured for heating an aerosol-forming substrate arranged in the cavity.

[0068] The aerosol-generating device may comprise an auxiliary air channel. The auxiliary air channel may comprise an infusion air inlet. The auxiliary air channel may extend from the infusion air inlet to an auxiliary inlet opening into the cavity. The auxiliary air channel may extend from the infusion air inlet to an auxiliary inlet opening into the major airflow channel. The auxiliary inlet opening into the major airflow channel may be located downstream of the resistance-to-draw modifying mechanism. The auxiliary inlet opening into the major airflow channel may be located downstream of the cavity.

[0069] The auxiliary air channel may advantageously function synergistically together with the resistance-to-draw modifying mechanism. For example, when the resistance-to-draw modifying mechanism reduces the cross-sectional area of the major airflow channel in a humid environment, less air may pass through the major airflow channel and the cavity, and more air may pass through the auxiliary air channel. Thus, the total amount of airflow reaching a user may remain essentially constant, while less air passes through the heated cavity such that the hot aerosol effect may be reduced or avoided. The hot aerosol-effect may thus be reduced or avoided while maintaining the overall amount of airflow reaching a user. The hot aerosol-effect may thus be reduced or avoided while substantially maintaining the overall resistance-to-draw experienced by a user. The hot aerosol-effect may thus be reduced or avoided while maintaining a convenient user experience.

[0070] The auxiliary air channel may allow an enhanced airflow control. The presence of an auxiliary air channel may allow for additional control and manipulation of the airflow within the device. By introducing air through the infusion air inlet and directing it to the auxiliary inlet opening in the major airflow channel, the device may regulate the quantity and direction of the auxiliary air that mixes with the primary airflow. This may provide finer control over the aerosol generation process, allowing for optimized performance and desired outcomes.

[0071] A further advantage may be versatility in application. The incorporation of an auxiliary air channel downstream of the resistance-to-draw modifying mechanism and the cavity may enhance the versatility of the aerosol-generating device. It may enable the device to adapt to different conditions or applications by providing the means to introduce auxiliary air selectively and precisely into the major airflow channel.

[0072] The aerosol-generating device may comprise a mouthpiece. The infusion air inlet may be provided in the mouthpiece. The mouthpiece may be removably attachable.

[0073] According to an embodiment of the invention there is provided an aerosol-generating system comprising the aerosol-generating device as described herein and an article. The article may comprise an aerosol-forming substrate. The article may be an aerosol-generating article.

[0074] The article may comprise at least one infusion hole. The at least one infusion hole may be provided downstream of the aerosol-forming substrate. The at least one infusion hole may advantageously function synergistically together with the resistance-to-draw modifying mechanism. For example, when the resistance-to-draw modifying mechanism reduces the cross-sectional area of the major airflow channel in a humid environment, less air may pass through the major airflow channel and the cavity, and more air may pass through the at least one infusion hole. Thus, the total amount of airflow reaching a user may remain essentially constant, while less air passes through the heated cavity such that the hot aerosol effect may be reduced or avoided. The hot aerosol-effect may thus be reduced or avoided while maintaining the overall amount of airflow reaching a user. The hot aerosol-effect may thus be reduced or avoided while maintaining the overall resistance-to-draw experienced by a user. The hot aerosol-effect may thus be reduced or avoided while maintaining a convenient user experience. The aerosol-generating device may comprise at least one infusion air inlet. The at least one infusion air inlet may be provided in a mouthpiece of the device. The system may comprise an auxiliary airflow route. The system may be configured such that the auxiliary airflow route extends from the at least one fusion air inlet into the article via the at least one infusion hole of the article.

[0075] As used herein, the terms ‘proximal’, ‘distal’, ‘downstream’ and ‘upstream’ are used to describe the relative positions of components, or portions of components, of the aerosolgenerating device in relation to the direction in which a user draws on the aerosol-generating device during use thereof.

[0076] The aerosol-generating device may comprise a mouth end through which in use an aerosol exits the aerosol-generating device and is delivered to a user. The mouth end may also be referred to as the proximal end. In use, a user draws on the proximal or mouth end of the aerosol-generating device in order to inhale an aerosol generated by the aerosolgenerating device. Alternatively, a user may directly draw on an aerosol-generating article inserted into an opening at the proximal end of the aerosol-generating device. The opening at the proximal end may be an opening of the cavity. The cavity may be configured to receive the aerosol-generating article. The aerosol-generating device comprises a distal end opposed to the proximal or mouth end. The proximal or mouth end of the aerosol-generating device may also be referred to as the downstream end and the distal end of the aerosolgenerating device may also be referred to as the upstream end. Components, or portions of components, of the aerosol-generating device may be described as being upstream or downstream of one another based on their relative positions between the proximal, downstream or mouth end and the distal or upstream end of the aerosol-generating device.

[0077] As used herein, an ‘aerosol-generating device’ relates to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-forming substrate may be part of an aerosol-generating article, for example part of a smoking article. An aerosolgenerating device may be a smoking device that interacts with an aerosol-forming substrate of an aerosol-generating article to generate an aerosol that is directly inhalable into a user’s lungs thorough the user's mouth. An aerosol-generating device may be a holder. The device may be an electrically heated smoking device. The aerosol-generating device may comprise a housing, electric circuitry, a power supply, a heating chamber and a heating element.

[0078] As used herein with reference to the present invention, the term ‘smoking’ with reference to a device, article, system, substrate, or otherwise does not refer to conventional smoking in which an aerosol-forming substrate is fully or at least partially combusted. The aerosol-generating device of the present invention is arranged to heat the aerosol-forming substrate to a temperature below a combustion temperature of the aerosol-forming substrate, but at or above a temperature at which one or more volatile compounds of the aerosolforming substrate are released to form an inhalable aerosol.

[0079] The aerosol-generating device may comprise electric circuitry. The electric circuitry may comprise a microprocessor, which may be a programmable microprocessor. The microprocessor may be part of the controller. The electric circuitry may comprise further electronic components. The electric circuitry may be configured to regulate a supply of power to the heating element. Power may be supplied to the heating element continuously following activation of the aerosol-generating device or may be supplied intermittently, such as on a puff-by-puff basis. The power may be supplied to the heating element in the form of pulses of electrical current. The electric circuitry may be configured to monitor the electrical resistance of the heating element, and preferably to control the supply of power to the heating element dependent on the electrical resistance of the heating element.

[0080] The aerosol-generating device may comprise a power supply, typically a battery, within a main body of the aerosol-generating device. In one embodiment, the power supply is a Lithium-ion battery. Alternatively, the power supply may be a Nickel-metal hydride battery, a Nickel cadmium battery, or a Lithium based battery, for example a Lithium-Cobalt, a Lithium-lron-Phosphate, Lithium Titanate or a Lithium-Polymer battery. As an alternative, the power supply may be another form of charge storage device such as a capacitor. The power supply may require recharging and may have a capacity that enables to store enough energy for one or more usage experiences; for example, the power supply may have sufficient capacity to continuously generate aerosol for a period of around six minutes or for a period of a multiple of six minutes. In another example, the power supply may have sufficient capacity to provide a predetermined number of puffs or discrete activations of the heating element.

[0081] The cavity of the aerosol-generating device may have an open end into which the aerosol-generating article is inserted. The open end may be a proximal end. The cavity may have a closed end opposite the open end. The closed end may be the base of the cavity. The closed end may be closed except for the provision of air apertures arranged in the base. The base of the cavity may be flat. The base of the cavity may be circular. The base of the cavity may be arranged upstream of the cavity. The open end may be arranged downstream of the cavity. The cavity may have an elongate extension. The cavity may have a longitudinal central axis. A longitudinal direction may be the direction extending between the open and closed ends along the longitudinal central axis. The longitudinal central axis of the cavity may be parallel to the longitudinal axis of the aerosol-generating device.

[0082] The cavity may be configured as a heating chamber. The cavity may have a cylindrical shape. The cavity may have a hollow cylindrical shape. The cavity may have a shape corresponding to the shape of the aerosol-generating article to be received in the cavity. The cavity may have a circular cross-section. The cavity may have an elliptical or rectangular cross-section. The cavity may have an inner diameter corresponding to the outer diameter of the aerosol-generating article.

[0083] The airflow channel may run through the aerosol-generating device and into the cavity. Ambient air may be drawn into the aerosol-generating device, into the cavity and towards the user through the airflow channel. Downstream of the cavity, a mouthpiece may be arranged or a user may directly draw on the aerosol-generating article. The airflow channel may extend through the mouthpiece.

[0084] In any of the aspects of the disclosure, the heating element may comprise an electrically resistive material. Suitable electrically resistive materials include but are not limited to: semiconductors such as doped ceramics, electrically "conductive" ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum platinum, gold and silver. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminium- titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, gold- and iron- containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetai® and iron-manganese-aluminium based alloys. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated or coated with an insulating material or vice-versa, depending on the kinetics of energy transfer and the external physicochemical properties required.

[0085] As described, in any of the aspects of the disclosure, the heating element may be part of an aerosol-generating device. The aerosol-generating device may comprise an internal heating element or an external heating element, or both internal and external heating elements, where "internal" and "external" refer to the aerosol-forming substrate. An internal heating element may take any suitable form. For example, an internal heating element may take the form of a heating blade. Alternatively, the internal heater may take the form of a casing or substrate having different electro-conductive portions, or an electrically resistive metallic tube. Alternatively, the internal heating element may be one or more heating needles or rods that run through the center of the aerosolforming substrate. Other alternatives include a heating wire or filament, for example a Ni-Cr (Nickel-Chromium), platinum, tungsten or alloy wire or a heating plate. Optionally, the internal heating element may be deposited in or on a rigid carrier material. In one such embodiment, the electrically resistive heating element may be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track on a suitable insulating material, such as ceramic material, and then sandwiched in another insulating material, such as a glass. Heaters formed in this manner may be used to both heat and monitor the temperature of the heating elements during operation.

[0086] An external heating element may take any suitable form. For example, an external heating element may take the form of one or more flexible heating foils on a dielectric substrate, such as polyimide. The flexible heating foils can be shaped to conform to the perimeter of the substrate receiving cavity. Alternatively, an external heating element may take the form of a metallic grid or grids, a flexible printed circuit board, a molded interconnect device (MID), ceramic heater, flexible carbon fibre heater or may be formed using a coating technique, such as plasma vapour deposition, on a suitable shaped substrate. An external heating element may also be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track between two layers of suitable insulating materials. An external heating element formed in this manner may be used to both heat and monitor the temperature of the external heating element during operation.

[0087] As an alternative to an electrically resistive heating element, the heating element may be configured as an induction heating element. The induction heating element may comprise an induction coil and a susceptor. In general, a susceptor is a material that is capable of generating heat, when penetrated by an alternating magnetic field. When located in an alternating magnetic field. If the susceptor is conductive, then typically eddy currents are induced by the alternating magnetic field. If the susceptor is magnetic, then typically another effect that contributes to the heating is commonly referred to hysteresis losses. Hysteresis losses occur mainly due to the movement of the magnetic domain blocks within the susceptor, because the magnetic orientation of these will align with the magnetic induction field, which alternates. Another effect contributing to the hysteresis loss is when the magnetic domains will grow or shrink within the susceptor. Commonly all these changes in the susceptor that happen on a nano-scale or below are referred to as “hysteresis losses”, because they produce heat in the susceptor. Hence, if the susceptor is both magnetic and electrically conductive, both hysteresis losses and the generation of eddy currents will contribute to the heating of the susceptor. If the susceptor is magnetic, but not conductive, then hysteresis losses will be the only means by which the susceptor will heat, when penetrated by an alternating magnetic field. According to the invention, the susceptor may be electrically conductive or magnetic or both electrically conductive and magnetic. An alternating magnetic field generated by one or several induction coils heat the susceptor, which then transfers the heat to the aerosol-forming substrate, such that an aerosol is formed. The heat transfer may be mainly by conduction of heat. Such a transfer of heat is best, if the susceptor is in close thermal contact with the aerosol-forming substrate.

[0088] As used herein, the term ‘aerosol-generating article’ refers to an article comprising an aerosol-forming substrate that is capable of releasing volatile compounds that can form an aerosol. For example, an aerosol-generating article may be a smoking article that generates an aerosol that is directly inhalable into a user’s lungs through the user's mouth. An aerosolgenerating article may be disposable.

[0089] As used herein, the term ‘aerosol-forming substrate’ relates to a substrate capable of releasing one or more volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. An aerosol-forming substrate may conveniently be part of an aerosol-generating article or smoking article.

[0090] The aerosol-forming substrate may be a solid aerosol-forming substrate. The aerosolforming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds which are released from the substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may comprise an aerosol former that facilitates the formation of a dense and stable aerosol. Examples of suitable aerosol formers are glycerine and propylene glycol.

[0091] The aerosol-generating substrate preferably comprises homogenised tobacco material, an aerosol-former and water. Providing homogenised tobacco material may improve aerosol generation, the nicotine content and the flavour profile of the aerosol generated during heating of the aerosol-generating article. Specifically, the process of making homogenised tobacco involves grinding tobacco leaf, which more effectively enables the release of nicotine and flavours upon heating.

[0092] As used herein, the term "aerosol-generating system" refers to the combination of an aerosol-generating device with an aerosol-forming substrate. When the aerosol-forming substrate forms part of an aerosol-generating article, the aerosol-generating system refers to the combination of the aerosol-generating device with the aerosol-generating article. In the aerosol-generating system, the aerosol-forming substrate and the aerosol-generating device cooperate to generate an aerosol.

[0093] Below, there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0094] Example E1: An aerosol-generating device comprising: a cavity for receiving an aerosol-forming substrate; a major airflow channel extending from an air inlet to an air outlet via the cavity of the device; and a resistance-to-draw modifying mechanism comprising a wet expanding material, wherein the wet expanding material is in fluid connection with ambient air, wherein the wet expanding material is configured to expand its volume if in contact with water comprised in the ambient air, and wherein the device is configured such that a cross-sectional area of the major airflow channel is at least partly reduced as a result of an expansion of the wet expanding material.

[0095] Example E2: The aerosol-generating device according to Example E1, wherein the device is configured such that the cross-sectional area of the major airflow channel is at least partly reduced at a position upstream of the cavity as a result of an expansion of the wet expanding material.

[0096] Example E3: The aerosol-generating device according to Example E1 or Example E2, wherein the wet expanding material is attached to an inner wall of the major airflow channel.

[0097] Example E4: The aerosol-generating device according to Example E3, wherein the inner wall of the major airflow channel comprises a recess, wherein the wet expanding material is arranged at least partly within the recess.

[0098] Example E5: The aerosol-generating device according to any of the preceding examples, wherein the major airflow channel comprises a first air channel portion with a first cross-sectional area and a second air channel portion with a second cross-sectional area, wherein the cross-sectional area of the major airflow channel is the sum of the first cross- sectional area and the second cross-sectional area, and wherein the resistance-to-draw modifying mechanism is configured such that only one of the first and second cross-sectional areas is at least partly reduced as a result of an expansion of the wet expanding material.

[0099] Example E6: The aerosol-generating device according to Example E5, wherein the first air channel portion surrounds the second air channel portion, and wherein the wet expanding material is attached to an inner wall of the first air channel portion.

[0100] Example E7: The aerosol-generating device according to Example E5, wherein the first air channel portion surrounds the second air channel portion, and wherein the wet expanding material is attached to an inner wall of the second air channel portion.

[0101] Example E8: The aerosol-generating device according to any of Examples E5 to E7, wherein one or both of the first and second air channel portions are at least partly tubular.

[0102] Example E9: The aerosol-generating device according to Example E1 or Example

[0103] E2, wherein the resistance-to-draw modifying mechanism comprises an air communication channel extending from a separate air inlet to a chamber, the chamber housing the wet expanding material, and wherein the resistance-to-draw modifying mechanism comprises a transmission means, the transmission means being configured to at least partly reduce the cross-sectional area of the major airflow channel as a result of an expansion of the wet expanding material.

[0104] Example E10: The aerosol-generating device according to Example E9, wherein the chamber is fluidly isolated from the major airflow channel within the device.

[0105] Example E11 : The aerosol-generating device according to Example E9 or Example E10, wherein the transmission means comprises a lever arrangement or a tap-like rotation arrangement.

[0106] Example E12: The aerosol-generating device according to Example E11, wherein the transmission means comprises a lever arrangement.

[0107] Example E13: The aerosol-generating device according to Example E12, wherein the lever arrangement comprises a small arm; a long arm; a lever axis; and a hatch, wherein the resistance-to-draw modifying mechanism is configured such that an expansion of the wet expanding material causes a movement of the small arm which, in turn, causes the long arm to rotate around the lever axis, such that the hatch moves inside the major airflow channel to at least partly reduce the cross-sectional area of the major airflow channel.

[0108] Example E14: The aerosol-generating device according to Example E13 or Example E14, wherein the resistance-to-draw modifying mechanism comprises a spring element configured to push a portion of the lever arrangement onto the wet expanding material.

[0109] Example E15: The aerosol-generating device according to any of the preceding examples, wherein the wet expanding material comprises one or more of a Super Absorbent Polymer (SAP), a water swellable elastomer, a silica gel, calcium chloride, wood, and a cellulose with low degree of acetylation.

[0110] Example E16: The aerosol-generating device according to Example E15, wherein the wet expanding material comprises a Super Absorbent Polymer (SAP) selected from one or more of sodium polyacrylate, polyacrylamide, and a starch-based polymer.

[0111] Example E17: The aerosol-generating device according to Example E15, wherein the wet expanding material comprises a cellulose with low degree of acetylation, and wherein the cellulose with low degree of acetylation is cotton.

[0112] Example E18: The aerosol-generating device according to Example E15, wherein the wet expanding material comprises a water swellable elastomer, and wherein the water swellable elastomer is selected from polyurethane elastomers, styrene-butadiene rubber (SBR), ethylene propylene diene monomer (EPDM), natural rubber, nitrile rubber, silicone rubber, chloroprene rubber, and fluoroelastomers.

[0113] Example E19: The aerosol-generating device according to any of the preceding examples, wherein the wet expanding material forms an integral piece together with at least one substrate which does not significantly expand when in contact with water.

[0114] Example E20: The aerosol-generating device according to any of the preceding examples, wherein the wet expanding material is provided on an inner wall of the major airflow channel, and wherein the wet expanding material occupies between 5 percent and 50 percent, preferably between 10 percent and 40 percent, more preferably between 10 percent and 35 percent, more preferably between 10 percent and 30 percent, more preferably between 10 percent and 20 percent of the cross-sectional area surrounded by the inner wall of the major airflow channel.

[0115] Example E21 : The aerosol-generating device according to any of the preceding examples, wherein the resistance-to-draw modifying mechanism is configured to reduce the cross-sectional area of the major airflow channel as a result of an expansion of the wet expanding material by between 5 percent and 50 percent, preferably between 10 percent and 40 percent, more preferably between 15 percent and 35 percent.

[0116] Example E22: The aerosol-generating device according to any of the preceding examples, wherein the resistance-to-draw modifying mechanism is configured such that the cross-sectional area of the at least a portion of the major airflow channel is reduced by at least 5 percent, preferably at least 10 percent, more preferably at least 15 percent in an ambient environment with a relative humidity of 100 percent at 20 degrees Celsius in comparison to an ambient environment with a relative humidity of 50 percent at 20 degrees Celsius.

[0117] Example E23: The aerosol-generating device according to any of the preceding examples, wherein the resistance-to-draw modifying mechanism is configured such that the cross-sectional area of the at least a portion of the major airflow channel is reduced by at least 5 percent, preferably at least 10 percent, more preferably at least 15 percent in an ambient environment with a relative humidity of 70 percent at 30 degrees Celsius in comparison to an ambient environment with a relative humidity of 20 percent at 20 degrees Celsius.

[0118] Example E24: The aerosol-generating device according to any of the preceding examples, wherein the wet expanding material is configured such that a volume of the wet expanding material increases by at least 10 percent, preferably at least 15 percent, more preferably at least 20 percent, more preferably at least 25 percent, more preferably at least 30 percent, more preferably at least 35 percent, more preferably 40 percent, more preferably at least 50 percent as a result of an increase in relative humidity of 50 percent at 20 degrees Celsius.

[0119] Example E25: The aerosol-generating device according to any of the preceding examples, wherein the resistance-to-draw modifying mechanism is configured to reduce the resistance-to-draw of the major airflow channel by at least 5 percent, preferably by at least 10 percent, more preferably by at least 15 percent, more preferably by at least 20 percent as a result of the expansion of the wet expanding material.

[0120] Example E26: The aerosol-generating device according to any of the preceding examples, wherein a cross-section of the major airflow channel is at least partly circular shaped.

[0121] Example E27: The aerosol-generating device according to any of the preceding examples, comprising a heater assembly configured for heating an aerosol-forming substrate arranged in the cavity.

[0122] Example E28: The aerosol-generating device according to any of the preceding examples, comprising an auxiliary air channel extending from an infusion air inlet to an auxiliary inlet opening into the major airflow channel, wherein the auxiliary inlet opening into the major airflow channel is located downstream of the resistance-to-draw modifying mechanism, preferably, downstream of the cavity.

[0123] Example E29: The aerosol-generating device according to Example E28, comprising a mouthpiece, wherein the infusion air inlet is provided in the mouthpiece, preferably wherein the mouthpiece is removably attachable.

[0124] Example E30: An aerosol-generating system comprising the aerosol-generating device according to one of the preceding examples and an article comprising an aerosolforming substrate.

[0125] Example E31 : The aerosol-generating system according to Example E30, wherein the article comprises at least one infusion hole, preferably wherein the at least one infusion hole is provided downstream of the aerosol-forming substrate.

[0126] Example E32: The aerosol-generating system according to Example E31, wherein the aerosol-generating device comprises a mouthpiece, and wherein the mouthpiece comprises at least one infusion air inlet.

[0127] Example E33: The aerosol-generating system according to Example E32, comprising an auxiliary airflow route, the auxiliary airflow route extending from the at least one fusion air inlet into the article via the at least one infusion hole of the article.

[0128] Features described in relation to one embodiment may equally be applied to other embodiments of the invention. The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

[0129] Figs. 1a to 1c show an aerosol-generating device;

[0130] Fig. 2 shows an aerosol-generating system;

[0131] Figs. 3a and 3b show a resistance-to-draw modifying mechanism;

[0132] Figs. 4a to 4c show resistance-to-draw modifying mechanisms;

[0133] Fig. 5 shows an aerosol-generating system; and

[0134] Figs. 6a to 6c show aerosol-generating systems.

[0135] Fig. 1a shows, in cross-sectional view, an aerosol-generating device 10 comprising a cavity 12 for receiving an aerosol-forming substrate. The aerosol-generating device 10 comprises a major airflow channel extending from an air inlet to 14 an air outlet 16 via the cavity 12 of the device. The major airflow channel comprises an upstream portion 18 extending from the air inlet 14 to a cavity inlet 20 of the cavity 12. The aerosol generating device 10 may comprise a heater assembly 22 configured for heating an aerosol-forming substrate arranged in the cavity 12.

[0136] The aerosol-generating device 10 comprises a resistance-to-draw modifying mechanism arranged in the upstream portion 18 of the major airflow channel as shown in Figs. 1b and 1c.

[0137] The resistance-to-draw modifying mechanism comprises a wet expanding material 24. The wet expanding material 24 is attached to an inner wall of the upstream portion 18 of the major airflow channel. The wet expanding material 24 is in fluid connection with ambient air via the air inlet 14 and the upstream portion 18 of the major airflow channel. The wet expanding material 24 is configured to expand its volume if in contact with water comprised in the ambient air.

[0138] Fig. 1b shows the wet expanding material 24 in an unexpanded state. This is due to the fact that the incoming air entering the device 10 via air inlet 14 possesses a low or standard concentration of water vapor.

[0139] The expanded state of the wet expanding material 24 is shown in Fig. 1c. This expansion occurs when the incoming air has a high concentration of water vapor. By the expansion of the wet expanding material 24 in Fig. 1c, in comparison to Fig. 1b, a reduction of the cross-sectional area of the major airflow channel in a direction perpendicular to a principal flow axis 26 of the airflow is achieved. The aerosol-generating device is thereby configured such that a cross-sectional area of the major airflow channel is at least partly reduced as a result of an expansion of the wet expanding material. As a result, the expanded wet material 24 in Fig. 1c restricts the amount of outside air that can pass through the major airflow channel, as compared to the configuration shown in Fig. 1b.

[0140] Fig. 2 shows an aerosol-generating system comprising the aerosol-generating device 10 of Figs. 1a-1c and an aerosol-generating article 100 comprising an aerosol-forming substrate. The aerosol-generating article 100 is inserted into the cavity 12.

[0141] The device 10 operates by drawing outside air 28 through the air inlet 14 into the major airflow channel which serves as the primary path for the airflow. The ambient air from outside enters the heated aerosol-generating article 100 to successively form an aerosol. Before reaching a user, this aerosol-air mixture 30 may be further combined with additional outside air 32 which may be drawn into the aerosol-generating article 100 through optional infusion holes 110. In a high humidity environment, a reduced airflow through the upper portion 18 of the major airflow channel may be at least partly compensated by an increased airflow through the infusion holes 110 such that the total volume of airflow may be held substantially constant for both low and high humidity environments.

[0142] Overall, Figs. 1 and 2 show the process within the device 10, involving the intake and mixing of outside air with aerosol, as well as the role of the wet expanding material 24 in regulating the airflow based on the water vapor concentration in the incoming air.

[0143] Figs. 3a and 3b show an embodiment of a resistance-to-draw modifying mechanism comprising an air communication channel extending from a separate air inlet 34 to a chamber 36, the chamber 36 housing the wet expanding material 24. The chamber 36 is fluidly isolated from the major airflow channel within the device.

[0144] The resistance-to-draw modifying mechanism comprises a transmission means. The transmission means is configured to at least partly reduce the cross-sectional area of the upper portion 18 of the major airflow channel as a result of an expansion of the wet expanding material 24. The transmission means comprises a lever arrangement. The lever arrangement comprises a small arm 38, a long arm 40, a lever axis 42, and a hatch 44. The resistance-to-draw modifying mechanism is configured such that an expansion of the wet expanding material 24 causes a movement of the small arm 38 which, in turn, causes the long arm 40 to rotate around the lever axis 42, such that the hatch 44 moves inside the upper portion 18 of the major airflow channel to reduce the cross-sectional area of the upper portion 18 of the major airflow channel. Movement of components is indicated by arrows in Fig. 3b.

[0145] The wet expanding material 24 has the capability to expand or contract based on the ambient conditions. It interacts with the lever mechanism which enables controlling the airflow inlet. In the initial configuration shown in Fig. 3a, the lever mechanism allows for relatively unimpeded airflow through the upper portion 18 of the major airflow channel. In Fig. 3b, the wet expanding material 24 is shown in an expanded state due to the presence of high humidity in the ambient air. This expansion exerts pressure on the small arm 38 of the lever mechanism, triggering the rotation of the long arm 40 around a lever axis 42. As a result, the hatch 44 is pushed, and thereby significantly restricting the cross-sectional area of the major airflow channel. This restriction leads to a controlled and reduced airflow passing through the major airflow channel, resulting in an increased resistance-to-draw within the device.

[0146] The expanded wet expanding material thus restricts the airflow and effectively increases its resistance-to-draw, causing it to move at a slower pace. This controlled airflow may aid in optimizing the performance and functionality of the device.

[0147] Simultaneously, the lever mechanism may direct the airflow towards the optional infusion air inlet(s) (not shown), providing an alternative path for air entry. By adjusting the position of the hatch 44, the lever mechanism may ensure that the airflow is redirected appropriately to meet the desired objectives of the device 10.

[0148] To maintain the adjustability and responsiveness of the lever mechanism, a spring mechanism (not shown) may be employed. This spring mechanism may apply a force on the lever mechanism, ensuring its return to the original position when the wet expanding material 24 dries out and reverts to its initial volume. The spring mechanism may contribute to the overall functionality and adaptability of the system.

[0149] In summary, Figs. 3a and 3b show a lever mechanism, demonstrating how the expansion of a wet expanding material 24 under humid conditions significantly restricts the airflow through the major airflow channel. This controlled airflow, characterized by an increased resistance-to-draw, may optimize the device's performance and may enhance its operational efficiency.

[0150] Figs. 4a to 4c show embodiments of a resistance-to-draw modifying mechanism, wherein the major airflow channel comprises a first air channel portion 46 with a first cross- sectional area 46’ and a second air channel portion 48 with a second cross-sectional area 48’, wherein the cross-sectional area of the major airflow channel is the sum of the first cross-sectional area 46’ and the second cross-sectional area 48’, and wherein the resistance-to-draw modifying mechanism is configured such that only one of the first and second cross-sectional areas 46’, 48’ is at least partly reduced as a result of an expansion of the wet expanding material 24. The embodiments of Figs. 4a to 4c may ensure that the expansion of the wet expanding material 24 does not obstruct the first air channel 46, allowing for the accurate calculation of the maximum resistance-to-draw of the major airflow channel.

[0151] Figs. 4a to 4c each show two cross-sectional views, wherein the right-hand side views show cut views along line A-A’ as indicated at the respective left-hand side views. Fig. 4a shows a part of the upstream portion 18 of the major airflow channel of the device 10 with the wet expanding material 24 being enclosed within a second air channel portion 48. This configuration effectively limits the expansion of the wet expanding material 24 by confining it within the walls of the second air channel portion 48.

[0152] Fig. 4b shows an alternative setup where the wet expanding material 24 is located in the bigger channel portion. Depending on the desired level of variation in the resistance-to- draw, one may choose between the embodiments of Fig. 4a and Fig. 4b.

[0153] Fig. 4c shows another embodiment, wherein the wet expanding material 24 is situated within a "mostly" closed recess to form the second portion 48 within the major airflow channel. As long as the expansion of the wet expanding material 24 is confined within the recess, this configuration may remain effective.

[0154] Figs. 4a to 4c show the versatility in incorporating the wet expanding material 24 into different configurations. By separating it within a second air channel portion 48, the expansion of the wet material 24 may be controlled and confined, enabling accurate assessment of the resistance-to-draw in the major airflow channel. These various configurations may offer flexibility in adapting the device 10 to meet specific requirements and target the desired variation in resistance-to-draw.

[0155] Fig. 5 shows an aerosol-generating system similar to the system of Fig. 2. The upper portion 18 of the major airflow channel comprises a recess filled with the wet expanding material 24 as shown in the magnified subs-section on the right hand-side. The upper portion 18 of the major airflow channel of the aerosol-generating device 10 exhibits a resistance-to- draw denoted as “R1”. Additionally, the aerosol-generating article 100 within the cavity 12 possesses its own resistance-to-draw denoted as “R2”, extending up to its infusion holes 110. The air flows 28 and 32 correspondingly pass through the major airflow channel and the aerosol-generating article 100, contributing to the overall airflow in the system.

[0156] Under normal conditions, the ratio of the air flow 28 relative to the total air flow drawn by the user (28 + 32) may be about 60%. However, in humid environmental conditions, this ratio may be targeted to decrease to about 50%. This adjustment is attributed to the presence of the wet expanding material 24. The wet expanding material 24 occupies a specific percentage “a(%)” of the length of the major airflow channel, which possesses a diameter “D” under standard conditions as shown in the magnified subs-section on the right hand-side. In humid environmental conditions, the wet expanding material expands such that the diameter “D” shrinks and the cross-sectional area of the major airflow channel shrinks correspondingly in the area where the wet expanding material 24 is provided. Thereby, less air will flow through the major airflow channel such that the ratio of the air flow 28 relative to the total air flow drawn by the user (28 + 32) may be reduced, for example from about 60 percent to about 50 percent.

[0157] Overall, Fig. 5 shows a configuration that aims to achieve specific air flow ratios under different environmental conditions. The presence of the wet expanding material 24 within the major airflow channel may play a crucial role in regulating the airflow and achieving the desired air flow distribution between the major airflow channel and the aerosol-generating article 100.

[0158] Figs. 6a to 6c show aerosol-generating systems. The devices 10 of Figs. 6a to 6c each comprise a resistance-to-draw modifying mechanism (not shown) provided upstream of the cavity 12 housing the article 100. The resistance-to-draw modifying mechanism may be, for example, resistance-to-draw modifying mechanisms as those explained in conjunction with Figs. 1 and 2 above.

[0159] Figs. 6a to 6c show various options for a system comprising an aerosol generating device 10 equipped with a heater assembly 22 configured to heat an aerosol-generating article 100 inserted into the cavity 12 of the device 10. The system features a major airflow channel comprising an upstream portion 18 through which outside air 28 is drawn. This air 28 subsequently passes into the aerosol-generating article 100, gets heated, and finally carries the generated aerosol to a user’s mouth.

[0160] The device 10 of the system of Fig. 6a comprises a mouthpiece part 60 that includes infusion air inlets 62. These inlets allow outside air 32 to be drawn into the device 10, but not directly into the aerosol-generating article 100. The mixture of aerosol, along with the air 32 drawn through the infusion air inlets 62, converges within the mouthpiece part 60 before being inhaled by the user.

[0161] In Fig. 6b, a similar system is presented, with the addition that the air 32 passing through the infusion air inlets 62 of the device's mouthpiece 60 also enters the article 100 through its infusion holes 110. This allows the air 32 to combine with the mixture of heated aerosol and air within the article 100 before reaching the user. In both the embodiments of Figs. 6a and 6b, the user draws additional air 32 into the system through the device's mouthpiece 60.

[0162] The devices 10 of Figs. 6a and 6b thus each comprise an auxiliary air channel extending from an infusion air inlet 62 into a downstream portion of the major airflow channel via a to an auxiliary inlet opening 64. The auxiliary inlet opening 64 into the major airflow channel is located downstream of the resistance-to-draw modifying mechanism.

[0163] Fig. 6c shows a system with a device 10 without a mouthpiece 60. Instead, the aerosol-generating article 100 itself comprises infusion holes 110 through which outside air 32 enters when the user directly inhales air 28 from the aerosol-generating article 100. In this case, the user bypasses the mouthpiece 60 and draws air directly from the aerosolgenerating article 100.

[0164] All Figs. 6a to 6c show a visual representation of the system's flexibility, presenting different options for the integration of a mouthpiece 60 and the infusion air inlets 62 and infusion holes 110. The various configurations may accommodate the user's preference for drawing air either through the device's mouthpiece 60 or directly from the aerosol-generating article 100. This may allow for a customizable and user-friendly experience.

Claims

CLAIMS1. An aerosol-generating device comprising: a cavity for receiving an aerosol-forming substrate; a major airflow channel extending from an air inlet to an air outlet via the cavity of the device; and a resistance-to-draw modifying mechanism comprising a wet expanding material, wherein the wet expanding material is in fluid connection with ambient air, wherein the wet expanding material is configured to expand its volume if in contact with water comprised in the ambient air, and wherein the device is configured such that a cross-sectional area of the major airflow channel is at least partly reduced as a result of an expansion of the wet expanding material.

2. The aerosol-generating device according to claim 1, wherein the device is configured such that the cross-sectional area of the major airflow channel is at least partly reduced at a position upstream of the cavity as a result of an expansion of the wet expanding material.

3. The aerosol-generating device according to claim 1 or claim 2, wherein the wet expanding material is attached to an inner wall of the major airflow channel.

4. The aerosol-generating device according to any of the preceding claims, wherein the major airflow channel comprises a first air channel portion with a first cross-sectional area and a second air channel portion with a second cross-sectional area, wherein the cross-sectional area of the major airflow channel is the sum of the first cross- sectional area and the second cross-sectional area, and wherein the resistance-to-draw modifying mechanism is configured such that only one of the first and second cross-sectional areas is at least partly reduced as a result of an expansion of the wet expanding material.

5. The aerosol-generating device according to claim 1 or claim 2, wherein the resistance-to-draw modifying mechanism comprises an air communication channel extending from a separate air inlet to a chamber, the chamber housing the wet expanding material, and wherein the resistance-to-draw modifying mechanism comprises a transmission means, the transmission means being configured to at least partly reduce the cross-sectional area of the major airflow channel as a result of an expansion of the wet expanding material,preferably wherein the chamber is fluidly isolated from the major airflow channel within the device.

6. The aerosol-generating device according to claim 5, wherein the transmission means comprises a lever arrangement.

7. The aerosol-generating device according to claim 6, wherein the lever arrangement comprises a small arm; a long arm; a lever axis; and a hatch, wherein the resistance-to-draw modifying mechanism is configured such that an expansion of the wet expanding material causes a movement of the small arm which, in turn, causes the long arm to rotate around the lever axis, such that the hatch moves inside the major airflow channel to at least partly reduce the cross-sectional area of the major airflow channel.

8. The aerosol-generating device according to any of the preceding claims, wherein the wet expanding material comprises one or more of a Super Absorbent Polymer (SAP), a water swellable elastomer, a silica gel, calcium chloride, wood, and a cellulose with low degree of acetylation.

9. The aerosol-generating device according to any of claims 1 , 2, 3, 4, and 8, wherein the wet expanding material is provided on an inner wall of the major airflow channel, and wherein the wet expanding material occupies between 5 percent and 50 percent, preferably between 10 percent and 40 percent, more preferably between 10 percent and 35 percent, more preferably between 10 percent and 30 percent, more preferably between 10 percent and 20 percent of the cross-sectional area surrounded by the inner wall of the major airflow channel.

10. The aerosol-generating device according to any of the preceding claims, wherein the resistance-to-draw modifying mechanism is configured to reduce the cross- sectional area of the major airflow channel as a result of an expansion of the wet expanding material by between 5 percent and 50 percent, preferably between 10 percent and 40 percent, more preferably between 15 percent and 35 percent.

11. The aerosol-generating device according to any of the preceding claims, wherein the resistance-to-draw modifying mechanism is configured such that the cross- sectional area of the at least a portion of the major airflow channel is reduced by at least 5percent, preferably at least 10 percent, more preferably at least 15 percent in an ambient environment with a relative humidity of 70 percent at 30 degrees Celsius in comparison to an ambient environment with a relative humidity of 20 percent at 20 degrees Celsius.

12. The aerosol-generating device according to any of the preceding claims, wherein the wet expanding material is configured such that a volume of the wet expanding material increases by at least 10 percent, preferably at least 15 percent, more preferably at least 20 percent, more preferably at least 25 percent, more preferably at least 30 percent, more preferably at least 35 percent, more preferably 40 percent, more preferably at least 50 percent as a result of an increase in relative humidity of 50 percent at 20 degrees Celsius.

13. The aerosol-generating device according to any of the preceding claims, wherein the resistance-to-draw modifying mechanism is configured to reduce the resistance- to-draw of the major airflow channel by at least 5 percent, preferably by at least 10 percent, more preferably by at least 15 percent, more preferably by at least 20 percent as a result of the expansion of the wet expanding material.

14. The aerosol-generating device according to any of the preceding claims, comprising an auxiliary air channel extending from an infusion air inlet to an auxiliary inlet opening into the major airflow channel, wherein the auxiliary inlet opening into the major airflow channel is located downstream of the resistance-to-draw modifying mechanism, preferably, downstream of the cavity.

15. An aerosol-generating system comprising the aerosol-generating device according to one of the preceding claims and an article comprising an aerosol-forming substrate.

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