Aerosol-generating device with improved inductor coil

Abstract

Am aerosol-generating device (12) comprising a cavity (41) that is configured to: removably receive at least a portion of a first aerosol-generating article (14), the first aerosol-generating article (14) comprising a first susceptor (31), and a first aerosol-forming substrate (26); and removably receive at least a portion of a second aerosol-generating article (114), separately from the first aerosol- generating article (14), the second aerosol-generating article (114) comprising a second susceptor (131), and a second aerosol-forming substrate (126), the second aerosol-forming substrate (126) being different from the first aerosol-forming substrate (26). The aerosol-generating device (12) further comprises a DC power supply (44), and an inductive heating arrangement (45) connected to the DC power supply (44). The inductive heating arrangement (45) comprises an inductor coil (42) comprising a litz wire, and the inductor coil (42) is arranged to generate an alternating magnetic field in the cavity (41) to heat a susceptor (31, 131) in a portion of an aerosol- generating article (14, 114) received in the cavity (41). The aerosol-generating device (12) further comprises power control electronics (43) configured to control the supply of power from the DC power supply (44) to the inductive heating arrangement (45) in a first heating profile, the first heating profile generating an alternating magnetic field in the cavity (41) that causes heating of the first susceptor (31) of the first aerosol-generating article (14) when the first aerosol-generating article (14) is received in the cavity (41). The power control electronics (43) are further configured to control the supply of power from the DC power supply (44) to the inductive heating arrangement (45) in a second heating profile, different to the first heating profile, to generate an alternating magnetic field in the cavity (41) that causes heating of the second susceptor (131) of the second aerosol-generating article (114) when the second aerosol-generating article (114) is received in the cavity (41).

Description

[0001] P / 90044.W001

[0002] 1

[0003] AEROSOL-GENERATING DEVICE WITH IMPROVED INDUCTOR COIL

[0004] The present disclosure relates to an aerosol-generating device. In particular, the present invention relates to an aerosol-generating device comprising an inductive heating arrangement that is configured to be used with different types of aerosol-generating article.

[0005] Some known aerosol-generating systems comprise an aerosol-generating device having an inductive heating arrangement, and an aerosol-generating article comprising an aerosol-forming substrate configured to be heated by the aerosol-generating device.

[0006] In some of these known systems, the aerosol-generating device comprises a power supply, such as a battery, power control electronics, and an inductive heating arrangement comprising an inductor coil, and the aerosol-generating article comprises a susceptor element. The inductor coil generates a varying magnetic field when supplied with a varying current, and the susceptor element is heated when it is arranged in the varying magnetic field. In use, the aerosol-generating article is inserted into a cavity of the aerosol-generating device, and a varying current is supplied to the inductor coil from the power supply to generate a varying magnetic field. The varying magnetic field penetrates the susceptor element, heating the susceptor element, which in turn heats the aerosol-forming substrate in the aerosol-generating article, releasing volatile components which condense to form an aerosol, which is inhalable by a user.

[0007] Different types of aerosol-generating articles and aerosol-forming substrates are also known. Some known aerosol-generating systems comprise an article holding a solid aerosolforming substrate. Different types of aerosol-forming substrate can require different heating arrangements and regimes to generate an optimal aerosol. Some known aerosol-generating systems comprise an article in the form of a cartridge holding a liquid aerosol-forming substrate. Accordingly, known aerosol-generating devices may not be configured to be used with different types of aerosol-generating articles and aerosol-forming substrates.

[0008] It would be desirable to provide an aerosol-generating device that is configured to be used with different types of aerosol-generating articles and aerosol-forming substrates. It would be desirable to provide an aerosol-generating device that is capable of generating an optimal aerosol from different types of aerosol-generating articles and aerosol-forming substrates.

[0009] According to the present disclosure, there is provided an aerosol-generating device. The aerosol-generating device may comprise a cavity. The cavity may be configured to removably receive at least a portion of an aerosol-generating article. The aerosol-generating device may comprise a DC power supply. The aerosol-generating device may comprise an inductive heating arrangement. The inductive heating arrangement may be connected to the DC power supply. The inductive heating arrangement may comprise an inductor coil. The inductor coil may comprise a litz wire. The inductor coil may be arranged to generate an alternating magnetic field in the cavity to heat a susceptor in a portion of an aerosol-generating article received in the cavity. The aerosolgenerating device may comprise power control electronics. The power control electronics may be configured to control the supply of power from the DC power supply to the inductive heating arrangement in a first heating profile. The first heating profile may generate an alternating magnetic field in the cavity that causes heating of a first susceptor of a first aerosol-generating article when the first aerosol-generating article is received in the cavity. The power control electronics may be configured to control the supply of power from the DC power supply to the inductive heating arrangement in a second heating profile, different to the first heating profile, to generate an alternating magnetic field in the cavity that causes heating of a second susceptor of a second aerosol-generating article, different to the first aerosol-generating article, when the second aerosol-generating article is received in the cavity.

[0010] According to the present disclosure, there is provided an aerosol-generating device. The aerosol-generating device comprises a cavity that is configured to: removably receive at least a portion of a first aerosol-generating article, the first aerosol-generating article comprising a first susceptor, and a first aerosol-forming substrate; and removably receive at least a portion of a second aerosol-generating article, separately from the first aerosol-generating article, the second aerosol-generating article comprising a second susceptor, and a second aerosol-forming substrate, the second aerosol-forming substrate being different from the first aerosol-forming substrate. The aerosol-generating device comprises a DC power supply. The aerosol-generating device also comprises an inductive heating arrangement connected to the DC power supply. The inductive heating arrangement comprises an inductor coil comprising a litz wire. The inductor coil is arranged to generate an alternating magnetic field in the cavity to heat a susceptor in a portion of an aerosol-generating article received in the cavity. The aerosol-generating device further comprises power control electronics. The power control electronics are configured to control the supply of power from the DC power supply to the inductive heating arrangement in a first heating profile, the first heating profile generating an alternating magnetic field in the cavity that causes heating of the first susceptor of the first aerosol-generating article when the first aerosol-generating article is received in the cavity. The power control electronics are further configured to control the supply of power from the DC power supply to the inductive heating arrangement in a second heating profile, different to the first heating profile, to generate an alternating magnetic field in the cavity that causes heating of the second susceptor of the second aerosol-generating article when the second aerosol-generating article is received in the cavity.

[0011] Litz wire is a type of wire comprised of a plurality of individual wires, each individual wire being electrically insulated from the other individual wires, and the individual wires being at least one of: bundled, twisted, woven, and bunched together. As used herein, “litz wire” refers to a wire comprised of a plurality of individual wires, each of the plurality of individual wires being electrically isolated from the other ones of the plurality of individual wires. A litz wire is especially suited to carry alternating currents, as the provision of a plurality of individual, electrically isolated wires, instead of a single wire having a large continuous cross-sectional area, reduces the skin effect and proximity effect losses in the wire when carrying an alternating current, particularly at high frequencies.

[0012] Advantageously, using a litz wire to form at least a portion of the inductor coil of the inductive heating arrangement of the aerosol-generating device may improve the efficiency of the inductive heating arrangement, compared to an inductive heating arrangement having an inductor coil formed from a single wire having a large cross-sectional area.

[0013] Advantageously, forming the inductor coil from litz wire may reduce the high frequency losses that would arise due to the skin effect in an equivalent inductor coil formed from a single stranded wire of similar diameter when a high frequency alternating current is driven through the inductor coil.

[0014] Typically, minimising the size and cost of an aerosol-generating device in a hand-held aerosol-generating system are highly important factors in the design of the system. In addition, in aerosol-generating systems in which an aerosol-generating device is configured to inductively heat a single type of aerosol-generating article, it is typically possible to design the aerosol-generating device and the aerosol-generating article to achieve a highly efficient coupling of an inductor coil in the aerosol-generating device to a susceptor in the aerosol-generating article. As a result, forming an inductor coil in an aerosol-generating device from a litz wire, which would typically increase the size and cost of the aerosol-generating device without providing appreciable improvements in efficiency, is generally not desirable.

[0015] However, the inventors have realised that specifically in aerosol-generating systems in which an aerosol-generating device is configured to be used to inductively heat multiple different types or designs of aerosol-generating articles, having differently arranged and configured susceptors, it is often not possible to optimise the design of the system to achieve highly efficient coupling between the inductor coil in the aerosol-generating device and the susceptor in all of the different types or designs of aerosol-generating articles. As such, the inventors have recognised that in aerosol-generating systems in which multiple different types or designs of aerosolgenerating article are inductively heated by a single aerosol-generating device, there is a need to improve the efficiency of the inductive heating arrangement in order to achieve efficient operation of the aerosol-generating system regardless of the aerosol-generating article that is used with the aerosol-generating device. Accordingly, the inventors have recognised that in these types of aerosol-generating systems, it is advantageous to form at least a portion of the inductor coil in the aerosol-generating device from a litz wire.

[0016] Preferably, each individual wire of the plurality of wires of a litz wire has a width or a diameter that is smaller than the skin depth of the wire at the frequency of the current that is to be driven through the litz wire, in order to minimise losses due to the skin effect and proximity effect. This may further increase the efficiency of the inductive heating arrangement, and allow the interior of the wire material of the inductor coil to contribute to the conductivity of the inductor coil.

[0017] In some preferred embodiments, the first aerosol-generating article is configured to be heated by a first heating profile, the first heating profile being a puff-actuated heating profile, and the second aerosol-generating article is configured to be heated by a second heating profile, the second heating profile being a continuous heating profile. Accordingly, the first aerosol-generating article has a first susceptor that is required to be relatively small, and to have a relatively low electrical resistance so that it may be heated and cooled quickly on puff actuation of the heating profile. In contrast, the second aerosol-generating article has a second susceptor that is required to be relatively large, and to have a relatively high electrical resistance compared to the second susceptor, in order to provide efficient continuous heating throughout the continuous heating profile. In these preferred embodiments, the inductor coil may be required to have a length that is larger than the length of the first susceptor, so that the length of the inductor coil is equivalent to the length of the second susceptor, and the inductor coil is configured to generate an alternating magnetic field in the cavity that penetrates the entire length of the second susceptor when the second susceptor is received in the cavity. As a result, the inductor coil may be optimised to couple with the second susceptor, and not optimised to couple with the first susceptor, which can result in reduced efficiency when heating the first susceptor compared to heating the second susceptor. Therefore, reducing losses in the inductor coil is particularly important in such systems, so that operation of the aerosol-generating system may be adequately efficient regardless of the aerosolgenerating article being heated by the aerosol-generating device. A reduction in losses in the inductor coil may be achieved by replacing a single stranded inductor coil with a litz wire inductor coil, which reduces the high frequency losses that would arise in the inductor coil due to the skin effect.

[0018] As used herein, “aerosol-generating system” refers to a system that interacts with an aerosol-forming substrate to generate an aerosol. Preferably, the aerosol-generating system is a system that interacts with an aerosol-forming substrate to generate an inhalable aerosol that is directly inhalable into a user’s lungs thorough the user's mouth. As used herein, an aerosolgenerating system comprises an aerosol-generating article and an aerosol-generating device. As used herein, “aerosol-forming substrate” refers to a substrate capable of releasing volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. In this disclosure, an aerosol-forming substrate refers to aerosol-forming substrates in any form, such as solid aerosol-forming substrates and liquid aerosolforming substrates.

[0019] As used herein, “aerosol-generating article” refers to an article comprising an aerosolforming substrate. An aerosol-generating article is typically configured for used with an aerosolgenerating device, which cooperate to generate an aerosol from the aerosol-forming substrate. An aerosol-generating article may be disposable.

[0020] The aerosol-generating article may be a cartridge. As used herein, “cartridge” refers to an article comprising an aerosol-forming substrate. A cartridge typically comprises a liquid aerosolforming substrate stored in a reservoir.

[0021] As used herein, “aerosol-generating device” refers to a device that is configured to interact with an aerosol-forming substrate or an aerosol-generating article comprising an aerosol-forming substrate to generate an aerosol. Typically, an aerosol-generating device is a portable device. Typically, an aerosol-generating device is a handheld device.

[0022] As used herein, “upstream” and “downstream” are used to describe the relative positions of components, or portions of components, of an aerosol-generating system. The terms upstream and downstream are relative to the direction of airflow or the flow of aerosol through the aerosol generating system when a user draws on the air outlet of the airflow path through the aerosolgenerating system.

[0023] As used herein, “puff” is used to describe the action of a user of the aerosol-generating system drawing on an air outlet of an airflow path through the aerosol-generating system to receive and inhale aerosol generated by the aerosol-generating system.

[0024] As used herein, “length” refers to the maximum dimension of a feature in a longitudinal direction of the feature.

[0025] As used herein, “width” or “diameter” refers to the maximum dimension of a feature in a transverse direction of the feature. The transverse direction is perpendicular to the longitudinal direction.

[0026] As used herein, “thickness” and “depth” refer to the maximum dimension of a feature in a direction perpendicular to the longitudinal direction of the feature and perpendicular to the transverse direction of the feature.

[0027] As used herein, “alternating current” refers to a current that periodically reverses direction. The alternating current may have any suitable frequency. Suitable frequencies for the alternating current may be between 100 kilohertz (kHz) and 30 megahertz (MHz), or between 1 megahertz (MHz) and 20 megahertz (MHz), or greater than 5 megahertz (MHz), or between 5 megahertz (5 MHz) and 15 megahertz (15 MHz) or around 6.78 megahertz (MHz). In some embodiments where the at least one inductor coil is a tubular inductor coil, the alternating current may have a frequency of between 500 kilohertz (kHz) and 30 megahertz (MHz). In some embodiments where the at least one inductor coil is a flat coil, the alternating current may have a frequency of between 100 kilohertz (kHz), and 1 megahertz (MHz).

[0028] The aerosol-generating device is configured to be used with different types of aerosolgenerating article. The cavity is configured to receive different types of aerosol-generating articles. The cavity of the aerosol-generating device may be configured to removably receive at least a portion of the first aerosol-generating article, the first aerosol-generating article comprising the first susceptor, and the first aerosol-forming substrate. The cavity of the aerosol-generating device may be configured to removably receive at least a portion of the second aerosol-generating article, separately from the first aerosol-generating article, the second aerosol-generating article comprising the second susceptor, and the second aerosol-forming substrate. In other words, the cavity may be configured to receive, individually, not simultaneously, at least a portion of the first aerosol-generating article, and at least a portion of the second aerosol-generating article. In other words, the cavity is not configured to receive both at least a portion of the first aerosol-generating article and at least a portion of the second aerosol-generating article at the same time.

[0029] The litz wire may comprise any suitable number of individual wires or strands. For example, the litz wire may comprise at least 500 individual wires, at least 1000 individual wires, at least 1500 individual wires, at least 2000 individual wires, or at least 2500 individual wires. The litz wire may comprise between 1000 and 4000 individual wires, or may preferably comprise around 2000 individual wires.

[0030] Each individual wire of the litz wire may have any suitable configuration. Each individual wire may have a circular cross-section, an oval cross-section, a square cross-section, a rectangular cross-section, or any other suitable cross-sectional shape.

[0031] Each individual wire of the litz wire may have a diameter of at least 10 microns (pm), or at least 15 microns (pm), or at least 20 microns (pm), or at least 30 microns, or at least 40 microns, or at least 50 microns.

[0032] Each of the individual wires of the litz wire may be surrounded by an electrically insulative material to electrically insulate the wire from the other ones of the plurality of wires. Each individual wire of the litz wire may have an electrically insulating coating. For example, each individual wire may have a coating of a polymeric material, such as polyurethane, polyesterimide, or polyimide. Particularly preferably, each individual wire is coated in an electrically insulating layer of polyurethane. Each individual wire of the litz wire may be formed from any suitable material. For example, each individual wire of the litz wire may be formed from: copper, silver, gold, aluminium, brass, zinc, iron, nickel, and alloys of thereof, and electrically conductive ceramics, such as yttrium-doped zirconia, indium tin oxide, and yttrium doped titanate.

[0033] The individual wires of the litz wire may be bundled or twisted together. The litz wire may be a multi stage litz wire, in which bundles of the individual wires are twisted together in multiple stages. The litz wire may be a multi stage litz wire having at least two, three, four, five, or six bundling stages. In some preferred embodiments, the litz wire has a four stage bundling construction.

[0034] The litz wire may have any suitable form. For example, the litz wire may have a circular cross-section, an oval cross-section, a square cross-section, a rectangular cross-section, or any other suitable cross-sectional shape.

[0035] The litz wire may have any suitable length of lay. As used herein, “length of lay” refers to the distance required for an individual wire of the litz wire to complete one rotation around the litz wire circumference. The litz wire may have a length of lay of between about 5 millimetres (mm) and about 30 millimetres (mm), or between about 5 millimetres (mm) and about 25 millimetres (mm), or between about 5 millimetres (mm) and about 20 millimetres (mm), or between about 10 millimetres (mm) and about 30 millimetres (mm), or between about 10 millimetres (mm) and about 25 millimetres (mm), or 10 millimetres (mm) and about 20 millimetres (mm), or between about 12 millimetres or about 18 millimetres (mm), or about 16 millimetres (mm).

[0036] The form of the litz wire may be optimised to minimise the total winding volume of the coil. The form of the litz wire may be optimised to minimise the outer diameter of the coil. The form of the litz wire is preferably optimised to minimise skin effect losses at the frequencies at which the current is driven through the inductor coil during operation of the aerosol-generating device. In particular, the litz wire form may be optimised to be driven with a current having a frequency of over 5 megahertz (MHz), and particularly at a frequency of around 6.78 megahertz (MHz). The diameter of the individual wires may be chosen to minimise skin effect losses at the operating frequencies of the aerosol-generating device. The number of individual wires of the litz wire may be chosen to achieve the desired resistance of the inductor coil. The number of bundles or bundling stages may be chosen to minimise skin effect losses at the bundle level at the operating frequencies of the aerosol-generating device.

[0037] The inductive heating arrangement of the aerosol-generating device comprises an inductor coil formed from litz wire. The inductor coil may have any suitable configuration to generate an alternating magnetic field in the cavity. The inductor coil may be arranged in any suitable location to generate an alternating magnetic field in the cavity. The inductor coil may be located in or around the cavity. The inductor coil may circumscribe the cavity. The inductor coil may be arranged at or near a boundary of the cavity. The inductor coil may be arranged at a side or an end of the cavity. The inductor coil may be at least partially wrapped around the cavity.

[0038] The inductor coil may have any suitable form. The inductor coil may be a tubular inductor coil. The inductor coil may be a cylindrical coil. The inductor coil may be a planar inductor coil. The inductor coil may be a flat inductor coil. Preferably, the inductor coil is a cylindrical, tubular coil that circumscribes the cavity.

[0039] The inductor coil may have any suitable number of turns.

[0040] The inductive heating arrangement may comprise any suitable number of inductor coils. For example, the inductive heating arrangement may comprise one, two, three, four, five or six inductor coils. The inductive heating arrangement may comprise a plurality of inductor coils. Each of the plurality of inductor coils may be configured to generate an alternating magnetic field in the cavity.

[0041] The power control electronics may be configured to control the supply of power from the DC power supply to the inductive heating arrangement in a first heating profile. The first heating profile may be any suitable type of heating profile for the first aerosol-generating article.

[0042] The first heating profile may be constant over time. The first heating profile may comprise supplying power to the inductive heating arrangement to heat the first susceptor of the first aerosolgenerating article to a target temperature. The first heating profile may vary with time. The first heating profile may comprise supplying power to the inductive heating arrangement to heat the first susceptor of the first aerosol-generating article to a target temperature that varies with time.

[0043] The power control electronics may be configured to control the supply of power from the DC power supply to the inductive heating arrangement in a second heating profile. The second heating profile may be any suitable type of heating profile for the second aerosol-generating article.

[0044] The second heating profile may be constant over time. The second heating profile may comprise supplying power to the inductive heating arrangement to heat the second susceptor of the second aerosol-generating article to a target temperature. The second heating profile may vary with time. The second heating profile may comprise supplying power to the inductive heating arrangement to heat the second susceptor of the second aerosol-generating article to a target temperature that varies with time.

[0045] In some embodiments, the heating profile is a continuous heating profile. In a continuous heating profile, the power control electronics are configured to continuously generate an alternating magnetic field in the cavity that causes continuous heating of a susceptor of an aerosol-generating article when the aerosol-generating article is received in the cavity. The strength of the alternating magnetic field generated in the continuous heating profile may remain constant. The strength of the alternating magnetic field generated in the continuous heating profile may vary over time. Typically, continuous heating profiles are most suitable for use with solid aerosol-forming substrates. The first heating profile may be a continuous heating profile. The second heating profile may be a continuous heating profile.

[0046] In some embodiments, the heating profile is a puff actuated heating profile. In a puff actuated heating profile, the power control electronics are configured to generate an alternating magnetic field in the cavity that causes heating of a susceptor of an aerosol-generating article when the aerosol-generating article is received in the cavity only when a puff is detected by the power control electronics. In some of these embodiments, the power control electronics are configured to detect when a user takes a puff on the aerosol-generating device. The power electronics may be further configured to generate an alternating magnetic field in the cavity that causes heating of a susceptor of an aerosol-generating article when the power control electronics detect when a user is taking a puff on the aerosol-generating device. Typically, puff actuated heating profiles are most suitable for use with liquid aerosol-forming substrates. The first heating profile may be a puff actuated heating profile. The second heating profile may be a puff actuated heating profile.

[0047] In some embodiments, the power control electronics comprise a puff sensor configured to detect when a user takes a puff on the aerosol-generating device. The puff sensor may be any suitable sensor configured to detect a user taking a puff on the aerosol-generating device. For example, the puff sensor may comprise at least one of an airflow sensor and a pressure sensor.

[0048] In some preferred embodiments, the power control electronics are configured to detect when a user takes a puff on the aerosol-generating device, and the first heating profile is a puff actuated heating profile, wherein the power control electronics are configured to generate an alternating magnetic field in the cavity that causes heating of the first susceptor of the first aerosolgenerating article when the power control electronics detect when a user is taking a puff on the aerosol-generating device. In some preferred embodiments, the second heating profile is a continuous heating profile, wherein the power control electronics are configured to continuously generate an alternating magnetic field in the cavity that causes continuous heating of the second susceptor of the second aerosol-generating article when the second aerosol-generating article is received in the cavity. In some of these preferred embodiments, the first aerosol-generating article comprises a liquid aerosol-forming substrate, and the second aerosol-generating article comprises a solid aerosol-forming substrate.

[0049] The power control electronics may be configured to determine whether an aerosolgenerating article is received in the cavity. The power control electronics may be configured to identify an aerosol-generating article received in the cavity. The power control electronics may be configured to determine whether an aerosolgenerating article is received in the cavity in an article detection mode. The power control electronics may be configured to identify an aerosol-generating article received in the cavity in an article detection mode. The article detection mode may be triggered or engaged when the aerosolgenerating device is turned on by a user. In some embodiments, the article detection mode may be triggered or engaged when the aerosol-generating device is extracted from a power charging unit. In some of these embodiments, the aerosol-generating device may be configured to detect the extraction of the device from a power charging unit.

[0050] The power control electronics may be configured to supply power to the inductive heating arrangement in probing pulses, and determine from the probing pulses at least one property of the inductive heating arrangement that changes when a susceptor of an aerosol-generating article is received in the cavity. The power control electronics may be configured to supply power to the inductive heating arrangement in probing pulses when the power control electronics are in the article detection mode.

[0051] In some embodiments, the power control electronics are configured to determine when an aerosol-generating article is received in the cavity based on the determined property of the inductive heating arrangement. In some embodiments, the power control electronics are configured to supply power to the inductive heating arrangement for heating an aerosol-generating article received in the cavity when it is determined that an aerosol-generating article is received in the cavity.

[0052] In some embodiments, the power control electronics are configured to determine when no aerosol-generating article is received in the cavity based on the determined property of the inductive heating arrangement. In some of these embodiments, the power control electronics are configured to notify a user that no aerosol-generating article is received in the cavity. In some of these embodiments, the power control electronics are configured to prevent the supply of power to the inductive heating arrangement for heating an aerosol-generating article when it is determined that an aerosol-generating article is not received in the cavity.

[0053] In some embodiments, the power control electronics are configured to determine when the first aerosol-generating article having the first susceptor and the first aerosol-forming substrate is received in the cavity based on the determined property of the inductive heating arrangement. When it is determined that the first aerosol-generating article is received in the cavity, the power control electronics may be configured to control the aerosol-generating device in the first mode.

[0054] In some embodiments, the power control electronics are configured to determine when the second aerosol-generating article having the second susceptor and the second aerosol-forming substrate is received in the cavity based on the determined property of the inductive heating arrangement. When it is determined that the second aerosol-generating article is received in the cavity, the power control electronics may be configured to control the aerosol-generating device in the second mode, different to the first mode.

[0055] Advantageously, determining the type of aerosol-generating article received in the cavity, and controlling the aerosol-generating device based on the detected type of aerosol-generating article, enables the aerosol-generating device to optimise the experience for a user of the aerosolgenerating device based on the type of aerosol-generating article that is used with the aerosolgenerating device.

[0056] In some embodiments, the controlling the aerosol-generating device in a first mode comprises notifying a user that the first aerosol-generating article is received in the cavity. In some embodiments, the controlling the aerosol-generating device in a second mode comprises notifying a user that the second aerosol-generating article is received in the cavity.

[0057] The notifying the user that the first aerosol-generating article is received in the cavity, and the notifying he user that the second aerosol-generating article is received in the cavity may take any suitable form. The notifying may comprise the power control electronics issuing a visual, audible, or haptic notification. For example, the power control electronics may issue at least one of: an audible notification, through a loudspeaker or a buzzer; a visual notification by displaying an icon or a message on a display; a visual notification by illumination a LED; and a haptic notification by actuating an actuator or a vibratable element.

[0058] In some preferred embodiments, the controlling the aerosol-generating device in a first mode comprises controlling the supply of power from the DC power supply to the inductive heating arrangement in the first heating profile to generate an alternating magnetic field in the cavity that causes heating of the first susceptor of the first aerosol-generating article to generate an aerosol from the first aerosol-forming substrate. In some preferred embodiments, the controlling the aerosol-generating device in a second mode comprises controlling the supply of power from the DC power supply to the inductive heating arrangement in the second heating profile, different to the first heating profile, to generate an alternating magnetic field in the cavity that causes heating of the second susceptor of the second aerosol-generating article to generate an aerosol from the second aerosol-forming substrate.

[0059] Separate from supplying power from the DC power supply to the inductive heating arrangement to generate an alternating magnetic field in the cavity that causes heating of a susceptor, the power control electronics may be configured to supply power to the inductive heating arrangement in probing pulses. The power control electronics may be configured to determine from the probing pulses at least one property of the inductive heating arrangement that changes when a susceptor of an aerosol-generating article is received in the cavity. The probing pulses may be pulses of current supplied to the inductor coil from the DC power supply. The probing pulses may generate an alternating magnetic field in the cavity. However, the strength and duration of the alternating magnetic field generated by the probing pulses is not sufficient to substantially heat a susceptor arranged in the cavity.

[0060] Preferably, the power supplied to the inductive heating arrangement in the probing pulses is not sufficient to generate an alternating magnetic field in the cavity to heat the first susceptor to generate an aerosol from the first aerosol-forming substrate when the first aerosol-generating article is received in the cavity.

[0061] Preferably, the power supplied to the inductive heating arrangement in the probing pulses is not sufficient to generate an alternating magnetic field in the cavity to heat the second susceptor to generate an aerosol from the second aerosol-forming substrate when the second aerosolgenerating article is received in the cavity.

[0062] The pulse duration of the probing pulses and the time interval between two consecutive probing pulses may be configured to provide a reliable measurement of the property, while minimising heat generation in a susceptor arranged in the cavity.

[0063] Each probing pulse may have any suitable pulse duration. For example, each probing pulse may have a pulse duration of between 1 microsecond and 500 microseconds, or between 10 microseconds and 300 microseconds, or between 15 microseconds and 120 microseconds, or between 30 microseconds to 100 microseconds. As used herein, the term "pulse duration" denotes the time interval during which the inductive heating arrangement is powered on to provide a probing pulse.

[0064] The time interval between two consecutive probing pulses may be any suitable interval. For example, the time interval between two consecutive power pulses may be between 50 milliseconds and 2 seconds, or between 100 milliseconds and 2 seconds, or between 500 milliseconds and 1 second.

[0065] The power control electronics may be configured to determine, from the probing pulses, at least one property of the inductive heating arrangement that changes when a susceptor of an aerosol-generating article is received in the cavity.

[0066] The property of the inductive heating arrangement may be any suitable property. The change in the property of the inductive heating arrangement that occurs when a susceptor of an aerosol-generating article is received in the cavity may be due to an interaction between an alternating magnetic field generated in the cavity by the inductive heating arrangement and the susceptor. The property of the inductive heating arrangement may be an electrical property of the inductive heating arrangement. The at least one property may be conductance, resistance, inductance, current, voltage, frequency, and phase. As used herein, the term "inductance" refers to the imaginary part of a complex impedance defined as the ratio of the supplied AC voltage to the measured AC current. Inductance, generally speaking, includes the property of an electric circuit to be susceptible to exterior electromagnetic influences. The property may be an equivalent resistance of the inductive heating arrangement. As used herein, the term "equivalent resistance" refers to the real part of a complex impedance defined as the ratio of the supplied AC voltage to the measured AC current. Accordingly, the "equivalent resistance" may also be denoted as the resistive load of the inductive heating arrangement.

[0067] Preferably, the at least one property is an electric property of the inductive heating arrangement. Preferably, the at least one property may be a magnetic property of the inductive heating arrangement. Particularly preferably, the property of the inductive heating arrangement is conductance.

[0068] The change of at least one property of the inductive heating arrangement may be due to a specific magnetic permeability and / or a specific electrical resistivity of the susceptor. That is, the susceptor within the aerosol-generating article may include a material having a specific magnetic permeability and / or a specific electrical resistivity.

[0069] The change of the property may be observed by measuring a change in a parameter of the inductive heating arrangement. The parameter may be measured either directly or indirectly. The presence of the susceptor, and therefore the article, may be determined by measuring the parameter and observing that the parameter has a different value in the presence of the susceptor compared to the value in the absence of the susceptor. Preferably, the parameter may be a current. Accordingly, the control circuitry may comprise a measurement device for measuring a current indicative of the at least one property of the inductive heating arrangement. In particular, the parameter may be a DC current supplied from the DC power supply to the inductive heating arrangement. Accordingly, the control circuitry may comprise a measurement device arranged and configured for measuring a DC current supplied from the DC power supply to the inductive heating arrangement. That is, the measurement device may comprise a DC current measurement device arranged in series connection between the DC power supply and the inductive heating arrangement. For example, the measurement device may comprise a resistance and a shunt amplifier.

[0070] The power control electronics are configured to control the supply of power to the inductor coil of the inductive heating arrangement. The power control electronics may be configured to control the supply of power to the inductor coil by controlling the supply of an alternating current to the inductor coil. The alternating current supplied to the inductor coil may have a frequency of between about 100 kilohertz (kHz), and about 30 megahertz (MHz), or between 1 megahertz (MHz) and 20 megahertz (MHz), or greater than 5 megahertz (MHz), or between 5 megahertz (5 MHz) and 15 megahertz (15 MHz) or around 6.78 megahertz (MHz).

[0071] In some preferred embodiments, the power control electronics comprise a controller. The controller may comprise a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application specific integrated chip (ASIC) or other electronic circuitry capable of providing control.

[0072] The power control electronics may be configured to supply an alternating current to the inductor coil continuously following activation of the aerosol-generating system. The power control electronics may be configured to supply current to the inductor coil intermittently, such as on a puff by puff basis.

[0073] The power control electronics may comprise further electronic components. The power control electronics may comprise a DC / AC inverter, which may comprise a Class-D power amplifier or a Class-E power amplifier.

[0074] The aerosol-generating device comprises a DC power supply. The DC power supply may comprise at least one of a battery and a capacitor. The DC power supply may be a battery. The battery may be any suitable type of battery. The battery may be a Lithium based battery, for example a Lithium-Cobalt, a Lithium-lron-Phosphate, a Lithium Titanate, or a Lithium-Polymer battery. The battery may be a Nickel metal hydride battery or a Nickel cadmium battery. The DC power supply may be another form of charge storage device, such as a capacitor. In some embodiments, the DC power supply has a DC supply voltage in the range of about 2.5 Volts to about 4.5 Volts, and a DC supply current in the range of about 1 Amp to about 10 Amps (corresponding to a DC power supply in the range of about 2.5 Watts to about 45 Watts).

[0075] The DC power supply and the power control electronics may be configured to operate at high frequency. The DC power supply and the power control electronics may be configured to supply a high frequency oscillating current to the inductor coil. As used herein, the term “high frequency oscillating current” means an oscillating current having a frequency of between about 100 kilohertz and about 30 megahertz. The high frequency oscillating current may have a frequency of from about 1 megahertz to about 30 megahertz, preferably from about 1 megahertz to about 10 megahertz and more preferably from about 5 megahertz to about 8 megahertz.

[0076] The power control electronics may be configured to control the supply of power to the inductor coil in any suitable way. In some embodiments, the power control electronics are configured to control the supply of power to the inductor coil in pulses. Where the power control electronics are configured to control the supply of power to the inductor coil in pulses, the power control electronics may be configured to control the supply of power to the inductor coil by pulse width modulation. The aerosol-generating device may form part of an aerosol-generating system. The aerosol-generating system may comprise an aerosol-generating device as described above, a first aerosol-generating article, and a second aerosol-generating article. The first aerosol-generating article may comprise a first susceptor, and a first aerosol-forming substrate. The second aerosolgenerating article may comprise a second susceptor, and a second aerosol-forming substrate. The second aerosol-forming substrate may be different from the first aerosol-forming substrate.

[0077] According to the present disclosure, there is provided an aerosol-generating system comprising: an aerosol-generating device as described above; a first aerosol-generating article; and a second aerosol-generating article. The first aerosol-generating article comprises a first susceptor, and a first aerosol-forming substrate. The second aerosol-generating article comprises a second susceptor, and a second aerosol-forming substrate. The second aerosol-forming substrate is different from the first aerosol-forming substrate.

[0078] In some preferred embodiments, the first aerosol-forming substrate is a liquid aerosolforming substrate.

[0079] In some preferred embodiments, the second aerosol-forming substrate is a solid aerosolforming substrate. Particularly preferably, the second aerosol-forming substrate may comprise a gathered, crimped sheet of homogenised tobacco material.

[0080] The aerosol-generating system may be a handheld aerosol-generating system. The aerosol-generating system may be a handheld aerosol-generating system configured to allow a user to draw on a mouthpiece end to draw an aerosol through the air outlet. The aerosolgenerating system may have a size comparable to a conventional cigar or cigarette. The aerosolgenerating system may have a total length between about 25 mm and about 150 mm. The aerosolgenerating system may have an external width or diameter between about 5 mm and about 30mm.

[0081] The first aerosol-generating article comprises an aerosol-forming substrate. The second aerosol-generating article comprises an aerosol-forming substrate.

[0082] The aerosol-forming substrate may form one of a plurality of component parts of an aerosolgenerating article. In some embodiments, the aerosol-forming substrate alone may form the aerosolgenerating article.

[0083] The aerosol-forming substrate may take any suitable form. Preferably, the aerosol-forming substrate may be a solid aerosol-forming substrate. The aerosol-forming substrate may be a liquid aerosol-forming substrate. The aerosol-forming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a solid. The aerosol-forming substrate may comprise a liquid. The aerosol-forming substrate may comprise a gel. The aerosol-forming substrate may comprise any combination of two or more of a solid, a liquid and a gel. The aerosol-forming substrate may comprise nicotine, a nicotine derivative, or a nicotine analogue. The aerosol-forming substrate may comprise one or more nicotine salts. The one or more nicotine salts may be selected from the list consisting of nicotine citrate, nicotine lactate, nicotine pyruvate, nicotine bitartrate, nicotine pectates, nicotine aginates, and nicotine salicylate.

[0084] The aerosol-forming substrate may comprise tobacco. Alternatively or in addition, the aerosolforming substrate may comprise a non-tobacco material or tobacco-substitute material containing aerosol-forming material.

[0085] Where the aerosol-forming substrate is a solid aerosol-forming substrate or comprises a solid aerosol-forming substrate, the solid aerosol-forming substrate may comprise, for example, one or more of: powder, granules, pellets, shreds, strands, strips, or sheets containing one or more of: herb leaf, tobacco leaf, tobacco ribs, expanded tobacco and homogenised tobacco.

[0086] Optionally, the solid aerosol-forming substrate may contain tobacco or non-tobacco volatile flavour compounds, which are released upon heating of the solid aerosol-forming substrate. The solid aerosol-forming substrate may also contain one or more capsules that, for example, include additional tobacco volatile flavour compounds or non-tobacco volatile flavour compounds and such capsules may melt during heating of the solid aerosol-forming substrate.

[0087] In some embodiments, the solid aerosol-forming substrate comprises homogenised tobacco material. As used herein, the term “homogenised tobacco material” refers to a material formed by agglomerating particulate tobacco.

[0088] The solid aerosol-forming substrate may comprise a gathered sheet of homogenised tobacco material. As used herein, the term “sheet” refers to a laminar element having a width and length substantially greater than the thickness thereof. As used herein, the term “gathered” is used to describe a sheet that is convoluted, folded, or otherwise compressed or constricted substantially transversely to the longitudinal axis of the aerosol-generating article.

[0089] The aerosol-forming substrate may comprise one or more botanicals, and / or one or more pharmaceutical agents.

[0090] Where the aerosol-forming substrate is a liquid aerosol-forming substrate or comprises a liquid aerosol-forming substrate, the liquid aerosol-forming substrate may comprise nicotine. The nicotine containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may comprise plant-based material. The liquid aerosol-forming substrate may comprise tobacco. The liquid aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds, which are released from the aerosol-forming substrate upon heating. The liquid aerosol-forming substrate may comprise homogenised tobacco material. The liquid aerosol-forming substrate may comprise a non-tobacco-containing material. The liquid aerosolforming substrate may comprise homogenised plant-based material. Where the aerosol-forming substrate comprises a liquid or a gel, the liquid may be located inside a container, or cartridge, or porous body. Where the aerosol-forming substrate is a liquid aerosol-forming substrate, the aerosol-generating article comprising the liquid aerosol-forming substrate may comprise a liquid reservoir configured to hold the liquid aerosol-forming substrate.

[0091] Where the aerosol-forming substrate comprises a liquid or a gel, in some embodiments, the aerosol-generating article may comprise an absorbent carrier. The aerosol-forming substrate may be coated on or impregnated into the absorbent carrier. For example, the nicotine compound and the aerosol-former may be combined with water as a liquid formulation. The liquid formulation may, in some embodiments, further comprise a flavourant. Such a liquid formulation may then be absorbed by the absorbent carrier or coated onto the surface of the absorbent carrier. The absorbent carrier may be a sheet or tablet of cellulosic-based material onto which the nicotine compound and the aerosol former may be coated or absorbed. The absorbent carrier may be a metallic, polymer or vegetal foam having liquid retaining and capillary properties and onto which the liquid or gel aerosol-forming substrate is coated or absorbed.

[0092] The aerosol-forming substrate may comprise an aerosol former. As used herein, an “aerosol former” refers to any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol and that is substantially resistant to thermal degradation at the operating temperature of the aerosol-generating article. Suitable aerosol-formers are well known in the art and include, but are not limited to: polyhydric alcohols, such as triethylene glycol, 1 ,3- butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Preferred aerosol formers are polyhydric alcohols or mixtures thereof, such as triethylene glycol, 1 ,3-butanediol and glycerine.

[0093] The aerosol-forming substrate may comprise a single aerosol former. Alternatively, the aerosol-forming substrate may comprise a combination of two or more aerosol formers.

[0094] The first aerosol-generating article comprises a first susceptor. The second aerosolgenerating article comprises a second susceptor.

[0095] Preferably, the second susceptor is different from the first susceptor.

[0096] The size of the second susceptor may be different from the size of the first susceptor. The length of the second susceptor may be different from the length of the first susceptor. The width of the second susceptor may be different from the width of the first susceptor. The thickness of the second susceptor may be different from the thickness of the first susceptor.

[0097] The second susceptor may be formed from a different material than the first susceptor. The second susceptor may have a different form or shape to the first susceptor. In some embodiments, the second susceptor is in the form of a strip, and the first susceptor is in the form of a mesh.

[0098] An electrical property of the second susceptor may be different to an electrical property of the first susceptor. A magnetic property of the second susceptor may be different to a magnetic property of the first susceptor. The electrical resistance of the second susceptor may be different to the electrical resistance of the first susceptor. The electrical resistance of the second susceptor at room temperature (i.e. at 20 degrees Celsius) may be different to the electrical resistance of the first susceptor at room temperature (i.e. at 20 degrees Celsius).

[0099] The second susceptor may be arranged in the second aerosol-generating article such that when the second aerosol-generating article is received in the cavity of the aerosol-generating device, the second susceptor is arranged in the cavity at a different location to the location of the first susceptor in the cavity when the first aerosol-generating article is received in the cavity. The second susceptor may be arranged in the second aerosol-generating article such that when the second aerosol-generating article is received in the cavity of the aerosol-generating device, the second susceptor is arranged in the cavity at a different orientation to the orientation of the first susceptor in the cavity when the first aerosol-generating article is received in the cavity.

[0100] The susceptor of an aerosol-generating article may have any suitable form and be formed from any suitable material.

[0101] Preferably, the susceptor comprises an electrically conductive material. For example, the susceptor may comprise a metallic material. The metallic material may be, for example, one of aluminium, nickel, iron, or alloys thereof, for example, carbon steel or ferritic stainless steel. Aluminium has an electrical resistivity of about 2.65 x 1O'08Ohm-meter, measured at room temperature (20°C), and a magnetic permeability of about 1.256 x 10'06Henry per meter. Likewise, ferritic stainless steel has an electrical resistivity of about 6.9 x 10'07Ohm-meter, measured at room temperature (20°C), and a magnetic permeability in a range of 1.26 x 10'03Henry per meter to 2.26 x 10-03Henry per meter.

[0102] Preferably, the susceptor comprises a magnetic material that is heatable by penetration with a varying magnetic field. The magnetic material may be a ferromagnetic material, such as ferrite, ferritic iron, a ferromagnetic alloy, a ferromagnetic steel, or a ferromagnetic stainless steel such as SAE 400 series stainless steels, SAE type 409, 410, 420 or 430 stainless steels.

[0103] As used herein, “magnetic material” refers to a material which is able to interact with a magnetic field, including both paramagnetic and ferromagnetic materials. In some preferred embodiments, the susceptor comprises at least about 5 percent, or at least about 20 percent, or at least about 50 percent, or at least about 90 percent of ferromagnetic or paramagnetic materials on a dry weight basis.

[0104] The susceptor may have any suitable form. The susceptor may be one of a particulate susceptor, or a susceptor filament, or a susceptor mesh, or a susceptor wick, or a susceptor pin, or a susceptor rod, or a susceptor blade, or a susceptor strip, or a susceptor sleeve, or a susceptor cup or a cylindrical susceptor, or a planar susceptor. For example, the susceptor may be an elongate susceptor strip having a length in a range of 4 millimetres to 16 millimetres, or 5 millimetres to 16 millimetres, or 6 millimetres to 16 millimetres, or 7 millimetres to 16 millimetres, or 8 millimetres to 16 millimetres, or 5 millimetres to 14 millimetres, or 5 millimetres to 12 millimetres, or 5 millimetres to 10 millimetres, or 5 millimetres to 9 millimetres, or 10 millimetres to 14 millimetres, or 7 millimetres, or 8 millimetres, or 9 millimetres, or 10 millimetres, or 11 millimetres, or 12 millimetres. The susceptor strip may have a width in a range of 1 millimetre to 6 millimetres, or

[0105] 1 millimetre to 5 millimetres, or 1 millimetre to 4 millimetres, or 1.5 millimetres to 3.5 millimetres, or

[0106] 2 millimetres to 6 millimetres, or 4 millimetres to 5 millimetres. The susceptor strip may have a thickness in a range of 0.03 millimetres to 0.15 millimetres, or 0.05 millimetres to 0.09 millimetres, or 0.08 millimetres to 0.12 millimetres, or 0.8 millimetres, or 0.1 millimetres, or 0.12 millimetres.

[0107] The susceptor may be a multi-layer susceptor, for example a multi-layer susceptor strip. In particular, the multi-layer susceptor may comprise a first susceptor material and a second susceptor material. The first susceptor material preferably is optimized with regard to heat loss and heating efficiency. For example, the first susceptor material may be aluminium, or a ferrous material such as a stainless steel. In contrast, the second susceptor material may be used as temperature marker. For this, the second susceptor material is chosen such as to have a Curie temperature corresponding to a predefined heating temperature of the susceptor. At its Curie temperature, the magnetic properties of the second susceptor material change from ferromagnetic to paramagnetic, accompanied by a temporary change of its electrical resistance. Thus, by monitoring a corresponding change of the electrical current absorbed by the inductive heating arrangement, it can be detected when the second susceptor material has reached its Curie temperature and, thus, when the predefined heating temperature has been reached. The second susceptor material preferably has a Curie temperature that is below the ignition point of the aerosolforming substrate, that is, preferably lower than 500 degrees Celsius. Suitable materials for the second susceptor material may include nickel and certain nickel alloys.

[0108] The invention is defined in the claims. However, 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. EX1. An inductive heating arrangement of an aerosol-generating device, wherein the inductive heating arrangement comprises an inductor coil comprising a litz wire.

[0109] EX2. An inductive heating arrangement according to example EX1 , wherein the litz wire comprises at least 500 individual wires, or at least 1000 individual wires, or at least 1500 individual wires, or at least 2000 individual wires, or at least 2500 individual wires.

[0110] EX3. An inductive heating arrangement according to example EX 1, wherein the litz wire comprises between 1000 and 4000 individual wires, or around 2000 individual wires.

[0111] EX4. An inductive heating arrangement according to any one of examples EX1 to EX3, wherein each individual wire of the litz wire has one of: a circular cross-sectional shape, an oval cross-sectional shape, a square cross-sectional shape, or a rectangular cross-sectional shape.

[0112] EX5. An inductive heating arrangement according to any one of examples EX1 to EX4, wherein each individual wire of the litz wire has a diameter of at least 10 microns (pm), or at least 15 microns (pm), or at least 20 microns (pm).

[0113] EX6. An inductive heating arrangement according to any one of examples EX1 to EX5, wherein each individual wire of the litz wire has an electrically insulating coating, and optionally wherein each individual wire has a coating of a polymeric material, optionally wherein the polymeric material is one of polyurethane, polyesterimide, or polyimide.

[0114] EX7. An inductive heating arrangement according to any one of examples EX1 to EX6, wherein the litz wire is a multi stage litz wire in which each individual wire of the litz wire is bundled or twisted together in multiple stages, and optionally wherein the multi stage litz wire comprises two, three, four, five, or six bundling stages.

[0115] EX8. An inductive heating arrangement according to any one of examples EX1 to EX7, wherein the litz wire has one of a circular cross-sectional shape, or an oval cross-sectional shape. Or a square cross-sectional shape, or a rectangular cross-sectional shape.

[0116] EX9. An inductive heating arrangement according to any one of examples EX1 to EX8, wherein the litz wire has a length of lay of between about 10 millimetres (mm) and about 20 millimetres (mm), or between about 12 millimetres or about 18 millimetres (mm), or about 16 millimetres (mm).

[0117] EX10. An aerosol-generating device comprising an inductive heating arrangement according to any one of examples 1 to 10.

[0118] EX11. An aerosol-generating device comprising: a cavity, wherein the cavity is configured to removably receive at least a portion of an aerosol-generating article comprising a susceptor and an aerosol-forming substrate; a DC power supply; an inductive heating arrangement according to any one of examples EX1 to EX10, wherein the inductive heating arrangement is connected to the DC power supply, and the inductor coil is arranged to generate an alternating magnetic field in the cavity to heat a susceptor in a portion of an aerosol-generating article received in the cavity; and power control electronics, wherein the power control electronics are configured to: control the supply of power from the DC power supply to the inductive heating arrangement in a first heating profile to generate an alternating magnetic field in the cavity that causes heating of a susceptor of an aerosol-generating article when an aerosolgenerating article is received in the cavity; and control the supply of power from the DC power supply to the inductive heating arrangement in a second heating profile, different to the first heating profile, to generate an alternating magnetic field in the cavity that causes heating of a susceptor of the aerosolgenerating article when an aerosol-generating article is received in the cavity.

[0119] EX12. An aerosol-generating device comprising: a cavity, wherein the cavity is configured to removably receive at least a portion of an aerosol-generating article comprising a susceptor and an aerosol-forming substrate; a DC power supply; an inductive heating arrangement connected to the DC power supply, the inductive heating arrangement comprising an inductor coil comprising a litz wire, wherein the inductor coil is arranged to generate an alternating magnetic field in the cavity to heat a susceptor in a portion of an aerosolgenerating article received in the cavity; and power control electronics, wherein the power control electronics are configured to: control the supply of power from the DC power supply to the inductive heating arrangement in a first heating profile to generate an alternating magnetic field in the cavity that causes heating of a susceptor of an aerosol-generating article when an aerosolgenerating article is received in the cavity; and control the supply of power from the DC power supply to the inductive heating arrangement in a second heating profile, different to the first heating profile, to generate an alternating magnetic field in the cavity that causes heating of a susceptor of the aerosolgenerating article when an aerosol-generating article is received in the cavity.

[0120] EX13. An aerosol-generating device comprising: a cavity, wherein the cavity is configured to: removably receive at least a portion of a first aerosol-generating article, the first aerosol-generating article comprising a first susceptor, and a first aerosol-forming substrate; and removably receive at least a portion of a second aerosol-generating article, separately from the first aerosol-generating article, the second aerosol-generating article comprising a second susceptor, and a second aerosol-forming substrate, the second aerosol-forming substrate being different from the first aerosol-forming substrate; a DC power supply; an inductive heating arrangement connected to the DC power supply, the inductive heating arrangement comprising an inductor coil comprising a litz wire, wherein the inductor coil is arranged to generate an alternating magnetic field in the cavity to heat a susceptor in a portion of an aerosolgenerating article received in the cavity; and power control electronics, wherein the power control electronics are configured to: control the supply of power from the DC power supply to the inductive heating arrangement in a first heating profile to generate an alternating magnetic field in the cavity that causes heating of the first susceptor of the first aerosol-generating article when the first aerosol-generating article is received in the cavity; and control the supply of power from the DC power supply to the inductive heating arrangement in a second heating profile, different to the first heating profile, to generate an alternating magnetic field in the cavity that causes heating of the second susceptor of the second aerosol-generating article when the second aerosol-generating article is received in the cavity.

[0121] EX14. An aerosol-generating device according to example EX12 or example EX13, wherein the litz wire comprises at least 500 individual wires, or at least 1000 individual wires, or at least 1500 individual wires, or at least 2000 individual wires, or at least 2500 individual wires.

[0122] EX15. An aerosol-generating device according to any one of examples EX12 to EX14, wherein the litz wire comprises between 1000 and 4000 individual wires, or around 2000 individual wires.

[0123] EX16. An aerosol-generating device according to any one of examples EX12 to EX15, wherein each individual wire of the litz wire has one of: a circular cross-sectional shape, an oval cross-sectional shape, a square cross-sectional shape, or a rectangular cross-sectional shape.

[0124] EX17. An aerosol-generating device according to any one of examples EX12 to EX16, wherein each individual wire of the litz wire has a diameter of at least 10 microns (pm), or at least 15 microns (pm), or at least 20 microns (pm).

[0125] EX18. An aerosol-generating device according to any one of examples EX12 to EX17, wherein each individual wire of the litz wire has an electrically insulating coating, and optionally wherein each individual wire has a coating of a polymeric material, optionally wherein the polymeric material is one of polyurethane, polyesterimide, or polyimide. EX19. An aerosol-generating device according to any one of examples EX12 to EX18, wherein the litz wire is a multi stage litz wire in which each individual wire of the litz wire is bundled or twisted together in multiple stages, and optionally wherein the multi stage litz wire comprises two, three, four, five, or six bundling stages.

[0126] EX20. An aerosol-generating device according to any one of examples EX12 to EX19, wherein the litz wire has one of a circular cross-sectional shape, or an oval cross-sectional shape. Or a square cross-sectional shape, or a rectangular cross-sectional shape.

[0127] EX21. An aerosol-generating device according to any one of examples EX12 to EX20, wherein the litz wire has a length of lay of between about 10 millimetres (mm) and about 20 millimetres (mm), or between about 12 millimetres or about 18 millimetres (mm), or about 16 millimetres (mm).

[0128] EX22. An aerosol-generating device according to any one of examples EX12 to EX21 , wherein the inductor coil circumscribes the cavity, and optionally wherein the inductor coil is a cylindrical coil.

[0129] EX23. An aerosol-generating device according to any one of examples EX12 to EX22, wherein the inductor coil is a flat coil, and optionally wherein the inductor coil is arranged at or near a boundary of the cavity.

[0130] EX24. An aerosol-generating device according to any one of examples EX12 to EX23, wherein the power control electronics are configured to control the supply of power to the inductor coil by controlling the supply of an alternating current to the inductor coil, the alternating current having a frequency of between about 100 kilohertz (kHz), and about 30 megahertz (MHz) ), or between 1 megahertz (MHz) and 20 megahertz (MHz), or greater than 5 megahertz (MHz), or between 5 megahertz (5 MHz) and 15 megahertz (15 MHz) or around 6.78 megahertz (MHz).

[0131] EX25. An aerosol-generating device according to any one of examples EX12 to EX24, wherein the first heating profile is a continuous heating profile, wherein the power control electronics are configured to continuously generates an alternating magnetic field in the cavity that causes continuous heating of the first susceptor of the first aerosol-generating article when the first aerosol-generating article is received in the cavity.

[0132] EX26. An aerosol-generating device according to any one of examples EX12 to EX25, wherein the power control electronics are configured to detect when a user takes a puff on the aerosol-generating device, and wherein the second heating profile is a puff actuated heating profile, wherein the power control electronics are configured to generate an alternating magnetic field in the cavity that causes heating of the second susceptor of the second aerosol-generating article when the power control electronics detect when a user is taking a puff on the aerosol-generating device, and when the second aerosol-generating article is received in the cavity. EX27. An aerosol-generating device according to any one of examples EX12 to EX26, wherein the power control electronics comprise a puff sensor configured to detect when a user takes a puff on the aerosol-generating device, and optionally wherein the puff sensor comprises at least one of an airflow sensor and a pressure sensor.

[0133] EX28. An aerosol-generating system comprising: an aerosol-generating device according to any one of examples EX10 to EX27; a first aerosol-generating article, the first aerosol-generating article comprising a first susceptor, and a first aerosol-forming substrate; and a second aerosol-generating article, the second aerosol-generating article comprising a second aerosol-forming substrate, separately from the first aerosol-generating article, the second aerosol-generating article comprising a second susceptor, and a second aerosol-forming substrate, the second aerosol-forming substrate being different from the first aerosol-forming substrate.

[0134] EX29. An aerosol-generating system according to example EX28, wherein the first aerosolforming substrate is a liquid aerosol-forming substrate.

[0135] EX30. An aerosol-generating system according to example EX28 or example EX29, wherein the second aerosol-forming substrate is a solid aerosol-forming substrate, and optionally wherein the second aerosol-forming substrate comprises a gathered, crimped sheet of homogenised tobacco material.

[0136] EX31. An aerosol-generating system according to any one of examples EX28 to EX30, wherein the size of the second susceptor is different from the size of the first susceptor, optionally wherein the length of the second susceptor is different from the length of the first susceptor, optionally wherein the width of the second susceptor is different from the width of the first susceptor, and optionally wherein the thickness of the second susceptor is different from the thickness of the first susceptor.

[0137] EX32. An aerosol-generating system according to any one of examples EX28 to EX31 , wherein the second susceptor is formed from a different material than the first susceptor.

[0138] EX33. An aerosol-generating system according to any one of examples EX28 to EX32, wherein the second susceptor has a different form or shape to the first susceptor, and optionally wherein the second susceptor is in the form of a strip, and the first susceptor is in the form of a mesh.

[0139] EX34. An aerosol-generating system according to any one of examples EX28 to EX33, wherein at least one of an electrical property of the second susceptor is different to an electrical property of the first susceptor, and a magnetic property of the second susceptor is different to a magnetic property of the first susceptor. EX35. An aerosol-generating system according to any one of examples EX28 toEX34, wherein the electrical resistance of the second susceptor at room temperature is different to the electrical resistance of the first susceptor at room temperature, and optionally wherein room temperature is 20 degrees Celsius.

[0140] The invention is further described, by way of example only, with reference to the accompanying drawings in which:

[0141] Figure 1 shows a schematic illustration of a first aerosol-generating article for an aerosolgenerating system according to an embodiment of the disclosure;

[0142] Figure 2 shows a schematic illustration of an aerosol-generating device of an aerosolgenerating system according to an embodiment of the disclosure;

[0143] Figure 3 shows a schematic illustration of an aerosol-generating system according to an embodiment of the present disclosure, the aerosol-generating system comprising the aerosolgenerating article of Figure 1, and the aerosol-generating device of Figure 2;

[0144] Figure 4 shows a schematic illustration of a second aerosol-generating article for an aerosolgenerating system according to an embodiment of the disclosure;

[0145] Figure 5 shows a schematic illustration of the aerosol-generating system of Figure 3, the aerosol-generating system comprising the aerosol-generating article of Figure 4, and the aerosolgenerating device of Figure 2;

[0146] Figure 6 shows a circuit diagram of the aerosol-generating device of Figure 2;

[0147] Figure 7 shows a schematic illustration of a graph of the evolution of probing current pulses l_DC with time of the aerosol-generating device of Figure 2, with the first aerosol-generating article of Figure 1 received in the cavity of the aerosol-generating device; and

[0148] Figure 8 shows a schematic illustration of a graph of the evolution of probing current pulses l_DC with time of the aerosol-generating device of Figure 2, with the second aerosol-generating article of Figure 4 received in the cavity of the aerosol-generating device.

[0149] An example of an aerosol-generating system 10 according to the present disclosure is shown in Figures 1-5. The aerosol-generating system 10 comprises an aerosol-generating device 12, and two aerosol-generating articles, a first aerosol-generating article 14 comprising a first aerosolforming substrate 26 and a first susceptor 31, and a second aerosol-generating article 114, the second aerosol-generating article 114 comprising a second aerosol-forming substrate 126 and a second susceptor 131.

[0150] Figure 1 shows a schematic illustration of the first aerosol-generating article 14 of the aerosol-generating system 10. The first aerosol-generating article 14 is in the form of a cartridge. The cartridge 14 comprises a cartridge housing 16, which is substantially tubular, defining an inner passage 19. The housing 16 defines a liquid reservoir 25 that is configured to hold the first aerosol-forming substrate 26. In this embodiment, the first aerosol-forming substrate comprises a liquid aerosolforming substrate of one of the types described above. The inner passage 19 extends centrally through the liquid reservoir 25 such that the liquid reservoir 25 is a substantially annular reservoir.

[0151] The cartridge 14 comprises a mouth end 20 and a connection end 21. At the mouth end 20, the cartridge 14 comprises an air outlet 22, in the form of an opening at one end of the inner passage 19. At the connection end 21 , the cartridge 14 comprises an air inlet 35, in the form of an opening at the opposite end of the inner passage 19 to the air outlet 22.

[0152] The cartridge 14 further comprises a heater assembly 30. The heater assembly 30 is generally in the form of a flat, planar sheet. The heater assembly 30 comprises a heating element 31 , in the form of the first susceptor 31 , and a wicking element 32 arranged in fluid communication with the first susceptor 31. In this embodiment, the first susceptor 31 comprises a sintered mesh formed from ferritic stainless steel filaments and austenitic stainless steel filaments. The wicking element 32 comprises a porous body of rayon filaments.

[0153] The heater assembly 30 is arranged to extend across the inner passage 19, with the first susceptor 31 arranged in the inner passage 19. The wicking element 32 extends outwardly beyond the first susceptor 31 at opposing ends, with each end extending through the housing 16 and into reservoir 25. In use, the first aerosol-forming substrate 26 held in the reservoir 25 comes into contact with the ends of the wicking element 32 of the heater assembly 30, and is drawn by capillary action through the wicking element 32 and onto the first susceptor 31 in the inner passage 19.

[0154] Figure 2 shows a schematic illustration of the aerosol-generating device 12 of the aerosolgenerating system 10.

[0155] The aerosol-generating device 12 comprises a connection end 38 and a distal end opposite the connection end 38. The aerosol-generating device 12 comprises a device housing 40, which defines a cavity 41 at the connection end 38. The cavity 41 is open at the connection end 38 of the aerosol-generating device 12, and is substantially closed at the opposite end.

[0156] The cavity 41 is configured to receive the connection end 21 of the first aerosol-generating article 14. The cavity 41 is also configured to receive a connection end 121 of the second aerosolgenerating article 114, which is described in more detail below with reference to Figures 4, and 5.

[0157] The aerosol-generating device 12 further comprises an inductor coil 42. In this embodiment, the inductor coil 42 is a helical coil circumscribing a portion of the cavity 41, and has a circular cross-section when viewed parallel to the longitudinal axis of the aerosol-generating device 12.

[0158] In this embodiment, the inductor coil 42 is formed from litz wire. The litz wire comprises 2000 strands of copper wire, each individual wire having a circular cross-section with a diameter of 20 microns (pm), and being coated in an electrically insulating layer of polyurethane. The litz wire is a multi stage litz wire, in which bundles of the individual wires are twisted together in multiple stages. The litz wire has a four stage bundling construction. In a first bundling stage, sixteen of the individual copper wires are bundled or twisted together, in a second bundling stage, five of the first bundles are bundled or twisted together, in a third bundling stage, five of the second bundles are bundled or twisted together, and in a fourth bundling stage, five of the third bundles are bundled or twisted together to form the multi stage litz wire. The litz wire has a circular cross-section and a length of lay of about 16 millimetres (mm).

[0159] In order to generate the required alternating magnetic field in the cavity 41 to heat a susceptor of an aerosol-generating article received in the cavity 41 , the inductor coil 42 is driven during use with a high frequency alternating current, typically at frequencies over 5 megahertz (MHz), and often at frequencies of around 6.78 megahertz (MHz). The inductor coil 42 is formed from a litz wire to reduce the high frequency losses that would arise due to the skin effect at such high frequencies in a single stranded wire of similar diameter. The relatively small diameter of the individual wires of the litz wire is required to avoid skin effect losses at the high operating frequencies, the relatively high number of wires is required to achieve a low resistance for the coil, and the relatively large number of bundling stages is required to keep the number of wires per stage low, to reduce skin effect losses in each bundle at the high operating frequencies.

[0160] The inductor coil 42 is arranged such that when the connection end 21 of the first aerosolgenerating article 14 is received in the cavity 41 of the aerosol-generating device 12, as shown in Figure 3, the inductor coil 42 is aligned with the susceptor 31 of the first aerosol-generating article 14.

[0161] The aerosol-generating device 12 further comprises power control electronics 43, and a DC power supply 44. The DC power supply 44 comprises a rechargeable lithium ion battery, which is rechargeable via an electrical connector (not shown) at a distal end of the aerosol-generating device 12, opposite the connection end 38. The power control electronics 43 comprise a controller (not shown) that is connected to the power supply 44, and to the inductor coil 42, such that the power control electronics 43 are able to control a supply of power to the inductor coil 42 from the DC power supply 44. The controller of the power control electronics 43, and the DC power supply 44 are configured to supply an alternating current to the inductor coil 42.

[0162] In this embodiment, the first susceptor 31, the inductor coil 42, and a portion of the power control electronics 43 together form an inductive heating arrangement 45 when the first susceptor 31 is received in the cavity 41 of the aerosol-generating device 12. In this embodiment, the inductor coil 42, and a portion of the power control electronics 43 together form the inductive heating arrangement 45 when the first susceptor 31 is not received in the cavity 41 of the aerosol-generating device 12. It will be appreciated that in other embodiments, the power control electronics may not form part of the inductive heating arrangement. In these embodiments, the inductive heating arrangement may comprise inductive heating electronics connected to the power control electronics. In these embodiments, the susceptor, the inductor coil, and the inductive heating electronics may form the inductive heating arrangement when the susceptor is received in the cavity of the aerosol-generating device, and the inductor coil, and the inductive heating electronics may form the inductive heating arrangement when the susceptor is not received in the cavity of the aerosol-generating device.

[0163] When an alternating current is supplied to the inductor coil 42, the inductor coil 42 generates an alternating magnetic field in the cavity 41. When the connection end 21 of the first aerosolgenerating article 14 is received in the cavity 41 of the aerosol-generating device 12, the alternating magnetic field generated by the inductor coil 42 is generated in the region of the first susceptor 31 , which is aligned with the inductor coil 42.

[0164] The aerosol-generating device 12 further comprises a flux concentrator 46, which partially surrounds the inductor coil 42 and is configured to attenuate the alternating magnetic field generated by the inductor coil 42 in the direction radially outwardly from the device. This may reduce interference between the alternating magnetic field and other nearby electronic devices and reduce the risk of the alternating magnetic field inductively heating nearby objects outside of the aerosolgenerating system.

[0165] Figure 3 shows the first aerosol-generating article 14 in use with the aerosol-generating device 12, with the connection end 21 of the first aerosol-generating article 14 received in the cavity 41 of the aerosol-generating device 12.

[0166] As shown in Figure 3, when the connection end 21 of the cartridge 14 is received in the cavity 41 , the inductor coil 42 is aligned with the heater assembly 30 of the first aerosol-generating article 14, such that the inductor coil 42 is aligned with the first susceptor 31. When the connection end 21 of the cartridge 14 is received in the cavity 41 , the alternating magnetic field generated by the inductor coil 42 is generated in the region of the first susceptor 31 .

[0167] Also as shown in Figure 3, when the connection end 21 of the cartridge 14 is received in the cavity 41 , an air inlet 48, and air gap 49 are defined between the first cartridge housing 18 and the device housing 40 to enable ambient air to be drawn into the aerosol-generating system 10. The air gap 49 extends the length of the connection end 21 of the cartridge 14 and the length of the cavity 41 to the air inlet 35 of the cartridge 14.

[0168] An airflow path is defined through the aerosol-generating system 10 when the connection end 21 of the cartridge 14 is received in the cavity 41. The airflow path comprises the air inlet 48, the air gap 49, the air inlet 35, the inner passage 19, and the air outlet 22. A user may draw on the mouth end 20 of the cartridge 14, and draw ambient air into the aerosol-generating system 10 at the air inlet 48, through the airflow path, and out of the aerosol-generating system 10 at the air outlet 22. Air drawn through the inner passage 19 of the cartridge 14 flows over the first susceptor 31.

[0169] In use, the connection end 21 of the cartridge 14 is inserted into the cavity 41 of the aerosolgenerating device 12. The power control electronics 43 determine that the cartridge 14 is received in the cavity 41 , as described in more detail below, and supply power from the DC power supply 44 to the inductive heating arrangement 45 in a first heating profile, which in this embodiment is a puff- actuated heating profile. When a user takes a puff on the mouth end 20 of the cartridge 14, air is drawn into the aerosol-generating system 10 at the air inlet 48, through the air gap 49. The user’s puff is detected by the power control electronics 43, and the controller of the power control electronics 43 determines that a puff has been taken on the aerosol-generating system 10. The power control electronics 43, on detecting a puff, cause an alternating current from the power supply 44 to be supplied to the inductor coil 42, which generates an alternating magnetic field in the cavity 41. The first susceptor 31 of the cartridge 14 is penetrated by the alternating magnetic field and is heated by Joule heating through induction of eddy currents in the susceptor and through hysteresis losses. The heated first susceptor 31 heats liquid first aerosol-forming substrate 26 drawn from the reservoir 25 by the wicking element 32 to the first susceptor 31 , and the heated aerosol-forming substrate 26 releases volatile compounds as a vapour into the inner passage 19 of the cartridge 14. The vapour is entrained in airflow through the inner passage 19, cools as it is drawn along the inner passage 19, and condenses to form an aerosol. The aerosol is drawn out of the aerosol-generating system 10 at the air outlet 22 of the cartridge 14, where it is inhaled by the user.

[0170] Figure 4 shows a schematic illustration of the second aerosol-generating article 114 of the aerosol-generating system 10.

[0171] The second aerosol-generating article 114 comprises a mouth end 120 and a connection end 121.

[0172] At the mouth end 120, the second aerosol-generating article 114 comprises a mouthpiece element 115, and a hollow tubular segment 117. The mouthpiece element 115 is arranged at a location immediately downstream of the hollow tubular segment 117, such that an upstream end of the mouthpiece element 115 abuts the downstream end of the hollow tubular segment 117.

[0173] The mouthpiece element 115 is provided in the form of a cylindrical plug of low-density cellulose acetate. The mouthpiece element 115 has a length of about 12 millimetres, and an external diameter of about 7.25 millimetres.

[0174] The hollow tubular segment 117 is provided in the form of a hollow cylindrical tube made of cellulose acetate. The hollow tubular segment 117 defines an internal cavity that is substantially empty, and so substantially unrestricted airflow is enabled along the internal cavity. The hollow tubular segment 17 has a length of about 8 millimetres, an external diameter of about 7.25 millimetres, and an internal diameter (DSTS) of about 3.25 millimetres. A thickness of a peripheral wall of the hollow tubular segment 17 is about 2 millimetres.

[0175] At the connection end 121 , the second aerosol-generating article 114 comprises a rod of the second aerosol-forming substrate 126. In this embodiment, the rod of the second aerosol-forming substrate 126 comprises a solid aerosol-forming substrate of one of the types described above. The rod of the second aerosol-forming substrate 126 has an external diameter of about 7.25 millimetres and a length of about 12 millimetres.

[0176] At the connection end 121 , the second aerosol-generating article 114 further comprises the second susceptor 131 , in the form of an elongate susceptor element within the rod of the second aerosol-forming substrate 126. The second susceptor 131 is provided in the form of a strip and has a length of about 10 millimetres, a thickness of about 60 micrometres, and a width of about 4 millimetres.

[0177] In more detail, the second susceptor 131 is arranged substantially longitudinally within the rod of the second aerosol-forming substrate 126, such as to be approximately parallel to the longitudinal direction of the rod of the second aerosol-forming substrate 126. The second susceptor 131 is positioned in a radially central position within the rod of the second aerosol-forming substrate 126, and extends effectively along the longitudinal axis of the rod. The second susceptor 131 extends substantially from an upstream end to a downstream end of the rod of the second aerosol-forming substrate 126. In effect, the second susceptor 131 has the same length as the rod of the second aerosol-forming substrate 126.

[0178] At the connection end 121 , the second aerosol-generating article 114 further comprises an upstream element 133 located immediately upstream of the rod of the second aerosol-forming substrate 126. The upstream element 133 is in longitudinal alignment with the rod of the second aerosol-forming substrate 126. A downstream end of the upstream element 133 abuts an upstream end of the rod of the second aerosol-forming substrate 126. This arrangement advantageously prevents the second susceptor 131 from being dislodged. Further, this arrangement ensures that the consumer cannot accidentally contact the second susceptor 131 after use, when it has been heated. The upstream element 133 is provided in the form of a cylindrical plug of cellulose acetate circumscribed by a stiff wrapper. The upstream element 133 has a length of about 5 millimetres. An upstream end 135 of the upstream element 133 is open to enable air to be drawn into the second aerosol-generating article 114 through the upstream end. Figure 5 shows the second aerosol-generating article 114 in use with the aerosol-generating device 12, with the connection end 121 of the second aerosol-generating article 114 received in the cavity 41 of the aerosol-generating device 12.

[0179] The inductor coil 42 is arranged such that when the connection end 121 of the second aerosolgenerating article 114 is received in the cavity 41 of the aerosol-generating device 12, as shown in Figure 5, the inductor coil 42 is aligned with the second susceptor 131 of the second aerosolgenerating article 114.

[0180] The inductor coil 42 has a similar length to the second susceptor 131 , such that the alternating magnetic field generated by the inductor coil 42 penetrates the length of the second susceptor 131 , when the second susceptor 131 is received in the cavity 41. In contrast, the first susceptor 31 has a length that is about half the length of the second susceptor 131. Accordingly, the inductor coil 42 has a length that is larger than the length of the first susceptor 31 . The alternating magnetic field generated by the inductor coil 42 penetrates the length of the first susceptor 31 , although the efficiency of the coupling between the inductor coil 42 and the first susceptor 31 is less than that between the inductor coil 42 and the second susceptor 131 in the second aerosol-generating article 114, as more energy is dissipated in the inductor coil 42 when it is coupled with the first susceptor 31 compared to when it is coupled with the second susceptor 131. In order to ensure that the aerosolgenerating system 10 operates with an acceptable efficiency (i.e. with minimal losses) when used with the first aerosol-generating article 14, it is particularly advantageous to use a litz wire to form the inductor coil 42 in this system.

[0181] Although in this embodiment the first susceptor 31 has a length that is about half the length of the second susceptor 131 , it will be appreciated that in other embodiments the first susceptor may have a length that is less than half the length of the second susceptor, or a length that is greater than half the length of the second susceptor. For example, the first susceptor may have a length that is a third the length of the second susceptor, or a quarter the length of the second susceptor. For example, the first susceptor may have a length that is two thirds the length of the second susceptor, or three quarters the length of the second susceptor.

[0182] In this embodiment, the second susceptor 131 , the inductor coil 42, and a portion of the power control electronics 43 together form an inductive heating arrangement 45 when the second susceptor 131 is received in the cavity 41 of the aerosol-generating device 12. In this embodiment, the inductor coil 42, and a portion of the power control electronics 43 together form the inductive heating arrangement 45 when the second susceptor 131 is not received in the cavity 41 of the aerosolgenerating device 12.

[0183] As shown in Figure 5, in use, when the connection end 121 of the second aerosol-generating article 114 is received in the cavity 41 , the upstream end 135 of the upstream element 133 of the second aerosol-generating article 114 abuts the closed end of the cavity 41 of the aerosolgenerating device 12.

[0184] Also as shown in Figure 5, when the connection end 121 of the second aerosol-generating article 114 is received in the cavity 41, an air inlet 48, and air gap 49 are defined between an outer surface of the second aerosol-generating article 114 and the device housing 40 to enable ambient air to be drawn into the aerosol-generating system 10.

[0185] An airflow path is defined through the aerosol-generating system 10 when the connection end 121 of the second aerosol-generating article 114 is received in the cavity 41. The airflow path comprises the air inlet 48, the air gap 49, and the second aerosol-generating article 114.

[0186] A user may draw on the mouth end 120 of the second aerosol-generating article 114, and draw ambient air into the aerosol-generating system 10 at the air inlet 48, through the airflow path, and out of the aerosol-generating system 10 at the mouthpiece element 115. Ambient air enters the aerosol-generating system 10 at the air inlet 48, between the second aerosol-generating article 114 and the device housing 40, through the air gap 49, and into the second aerosol-generating article 114 at the upstream end 135 of the upstream element 133. Air flows through the second aerosol-generating article 114, from the upstream end to the downstream end, through the upstream element 133, through the second aerosol-forming substrate 126, through the hollow tubular segment 117, and out of the aerosol-generating system 10 at the mouthpiece element 115.

[0187] In use, the connection end 121 of the second aerosol-generating article 114 is inserted into the cavity 41 of the aerosol-generating device 12. The power control electronics 43 determine that the second aerosol-generating article 114 is received in the cavity 41, as described in more detail below, and supply power from the DC power supply 44 to the inductive heating arrangement 45 in a second heating profile, which in this embodiment is a continuous heating profile. The power control electronics 43 cause an alternating current from the power supply 44 to be supplied to the inductor coil 42, which generates an alternating magnetic field in the cavity 41. The second susceptor 131 of the second aerosol-generating article 114 is penetrated by the alternating magnetic field and is heated by Joule heating through induction of eddy currents in the susceptor, and through hysteresis losses. The heated second susceptor 131 heats the second aerosol-forming substrate 126, which releases volatile compounds in a vapour. When a user takes a puff on the mouthpiece element 115 of the second aerosol-generating article 114, air is drawn into the aerosol-generating system 10 at the air inlet 48, through the air gap 49, and into the second aerosol-generating article 114 at the upstream end 135 of the upstream element 133. The vapour from the heated second aerosolforming substrate 126 is entrained in the airflow through the second aerosol-forming substrate 126, and cools and condenses into an aerosol as it is drawn along the second aerosol-generating article 114 to the mouthpiece element 115. The aerosol is drawn out of the aerosol-generating system 10 at the mouthpiece element 115, where it is inhaled by the user.

[0188] Figure 6 shows further details of the inductive heating arrangement 45 used to generate an alternating magnetic field within the cavity 41 of the aerosol-generating device 12. According to the present embodiment, the inductive heating arrangement 45 comprises a DC / AC inverter which is connected to the DC power supply 44, shown in Figures 2, 3, and 5. The DC / AC inverter includes a Class-E power amplifier which in turn includes the following components: a transistor switch 51 comprising a Field Effect Transistor T (FET), for example a Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET), a transistor switch supply circuit indicated by the arrow 52 for supplying the switching signal (gate-source voltage) to the transistor switch 51, and an LC load network 53 comprising a shunt capacitor C1 and a series connection of a capacitor C2 and inductor L2. The inductor L2 corresponds to the inductor coil 42 shown in Figures 2, 3, and 5 used to generate an alternating magnetic field within the cavity 41. In addition, there is provided a choke L1 for supplying a DC supply voltage +V_DC from the DC power supply 44. Also shown in Figure 6 is the ohmic resistance R representing the total equivalent resistance or total resistive load 54, which - in use of the system, that is, when the article is inserted in the cavity 41 of the aerosol-generating device 12 - is the sum of the ohmic resistance of the inductor coil 42, marked as L2, and the ohmic resistance of the susceptor 31. Otherwise, in case no article is inserted in the cavity 41, the equivalent resistance or resistive load 54 only corresponds to the ohmic resistance of the inductor coil 42.

[0189] Further details of the inductive heating arrangement 45 according to the present embodiment, in particular with regard to its working principles, are disclosed, for example, in WO 2015 / 177046 A1.

[0190] The power control electronics 43 of the aerosol-generating device 12 are configured to detect insertion of an aerosol-generating article into the cavity 41, and to automatically enable or disable the heating process based on whether an aerosol-generating article is received in the cavity 41. The power control electronics 43 are also configured to identify the type of aerosol-generating article received in the cavity 41, and to adapt the heating process to the type of aerosol-generating article that is received in the cavity 41.

[0191] Detection of insertion of an aerosol-generating article in the cavity 41, and identification of the type of aerosol-generating article received in the cavity 41 is realized via the inductive heating arrangement 45 itself. Advantageously, this avoids the need for separate sensors. Detection of an aerosol-generating article received in the cavity 41, and identification of the type of aerosolgenerating article received in the cavity 41 is achieved by detecting at least one property of the inductive heating arrangement 45 that changes when a susceptor of an aerosol-generating article is received in the cavity 41.

[0192] Detection of insertion of an aerosol-generating article, and identification of the type of aerosol-generating article received in the cavity 41 is achieved by detection of a change in at least one property of the inductive heating arrangement 45 due to the presence of the susceptor when an aerosol-generating article is received in the cavity 41.

[0193] In the present embodiment, the conductance of the total resistive load 54 of the inductive heating arrangement 45 is used as a property of the inductive heating arrangement 45 that is monitored to detect insertion of an aerosol-generating article into the cavity 41 , and to determine the type of aerosol-generating article that is received in the cavity 41. The value of the conductance of the total resistive load 54 of the inductive heating arrangement 45 depends on the presence of a susceptor of an aerosol-generating article in the cavity 41, in close proximity to the inductor coil 42.

[0194] When an aerosol-generating article is inserted in the cavity 41 of the aerosol-generating device 12, the conductance of the total resistive load 54 of the inductive heating arrangement 45 comprises the combination of the conductance of the inductor coil 42 and the conductance of the susceptor of the aerosol-generating article. Whereas, when an aerosol-generating article is not received in the cavity 41 of the aerosol-generating device 12, the conductance of the total resistive load 54 of the inductive heating arrangement 45 comprises the conductance of the inductor coil 42 only, without the conductance of a susceptor.

[0195] The difference in the conductance of the total resistive load 54 of the inductive heating arrangement 45 when an aerosol-generating article is received in the cavity 41 compared to when an aerosol-generating article is not received in the cavity 41 may be detected via the DC current l_DC provided from the DC power supply 44 to the inductive heating arrangement 45, that is, to the LC load network 53. For this, the power control electronics 43 comprise a current measurement device 55 arranged in series connection between the DC power supply 44 and the LC load network 53. Accordingly, when an aerosol-generating article is inserted into the cavity 41 of the aerosolgenerating device 12, the presence of the susceptor of the aerosol-generating article in the cavity 41 decreases the conductance of the total resistive load 54 of the inductive heating arrangement 45. This in turn causes a decrease in the DC current feeding the inductive heating arrangement 45. The change in the DC current l_DC is detected by the current measurement device 55, which in turn is used to determine that an aerosol-generating article is received in the cavity 41 , and also to determine the type of aerosol-generating article received in the cavity 41. When it is determined that a known type of aerosol-generating article is received in the cavity 41, this triggers a signal to activate a heating operation of the inductive heating arrangement 45 that is specifically configured for heating the type of aerosol-generating article that is received in the cavity 41. The power control electronics 43 are configured to perform different heating operations of the inductive heating arrangement 45 for different types of aerosol-generating article, and different signals are triggered when it is determined that different types of aerosol-generating article are received in the cavity 41.

[0196] The power control electronics 43 are configured to operate the aerosol-generating device 12 in an article detection mode before it is determined that an aerosol-generating article is received in the cavity 41. This reduces power consumption compared to continuous operation in a heating mode. The article detection mode is triggered when the aerosol-generating device 12 is turned on by a user. The article detection mode is a pulsed mode, in which the power control electronics 43 supply power to the inductive heating arrangement 45 from the DC power supply 44 in a series of probing pulses. For this, the power control electronics 43 comprise a switch 56 that is arranged and configured to control a supply of power from the DC power supply 44 to the inductive heating arrangement 45. In the present embodiment, the switch 56 is arranged in series connection between the DC power supply 44 and the LC load network 53. During the article detection mode, the switch 56 is intermittently opened and closed such as to generate probing pulses for intermittently powering on the inductive heating arrangement 45. In contrast, during some heating modes of the aerosol-generating device 12, the switch 56 may be permanently closed to continuously apply a DC voltage from the DC power supply 44 to the inductive heating arrangement 45.

[0197] As shown in Figure 6, the switch 56 and the current measurement device 55 are both part of a control circuit which also includes a microprocessor 57. The microprocessor 57 is configured to control the switch 56 used to generate the probing pulses for intermittently powering on the inductive heating arrangement 45, to read out the measurement device 55 for measuring the current l_DC supplied from the DC power supply to the inductive heating arrangement 45, and to control the transistor switch driver circuit 52 of the inductive heating arrangement 45.

[0198] In the article detection mode, the microprocessor 57 starts driving the switch 56 by closing it for a pre-determined closing time interval, thereby generating a probing pulse, which is a current pulse having a pulse duration T1, corresponding to the closing time interval. The pulse duration T1 of the probing pulse may be in a range between 1 microsecond and 500 microseconds, in particular between 10 microseconds and 300 microseconds, preferably between 15 microseconds and 120 microseconds, most preferably between 30 microseconds to 100 microseconds. At the end of the closing time interval, the microprocessor 57 opens the switch 56 again for a pre-determined opening time interval, thereby interrupting the current passage to the inductive heating arrangement 45. The opening time interval corresponds to the time interval between two consecutive probing pulses, which may be in a range between 50 milliseconds and 2 seconds, in particular between 100 milliseconds and 2 seconds, preferably between 500 milliseconds and 1 second. Closing and opening of the switch 56 may occur at regular time intervals such as to generate periodic probing pulses for periodically powering on the inductive heating arrangement 45. Thus, the sum of the closing time interval and the opening time interval, or the sum of the pulse duration and the time interval between two consecutive power pulses corresponds to the periodicity of the probing pulse series.

[0199] Figures 7 and 8 show graphs of the evolution of current pulses l_DC with time t according to an exemplary embodiment of the present invention.

[0200] Figure 7 is a graph showing the evolution of the probing pulses l_DC from the aerosolgenerating device 12 when the first aerosol-generating article 14 is received in the cavity 41.

[0201] Figure 8 is a graph showing the evolution of the probing pulses l_DC from the aerosolgenerating device 12 when the second aerosol-generating article 114 is received in the cavity 41.

[0202] When in the article detection mode, the power control electronics 43 generate a series of probing pulses, causing a pulsed alternating magnetic field to be generated in the cavity 41. The probing pulses have a pulse duration T1 of 100 microseconds and a time interval between two consecutive probing pulses of 1 second. It will be appreciated that these values are only exemplary and may change in other embodiments.

[0203] The current measuring device 55 measures the DC current feeding the inductive heating arrangement 45, which depends on the conductivity of the total resistive load 54 of the inductive heating arrangement 45.

[0204] As shown in Figure 7 and Figure 8, when no aerosol-generating article is received in the cavity 41, the current measuring device 55 measures a current having a value of l_NA (where “NA” stands for “no article”) for each probing pulse. In Figure 7 and Figure 8, the first four probing pulses indicate that no aerosol-generating article is received in the cavity 41, as the current measured for each probing pulse is l_NA.

[0205] When the current measured by the current measuring device 55, l_DC, is different from l_N A, this can indicate that an aerosol-generating article is received in the cavity 41.

[0206] When the first aerosol-generating article 14 is received in the cavity 41, the DC current feeding the inductive heating arrangement 45 is reduced, due to the reduced conductivity of the total resistive load 54 of the inductive heating arrangement 45. The reduced conductivity of the total resistive load 54 of the inductive heating arrangement 45 is reduced because the total resistive load 54 comprises the ohmic resistance of the inductor coil 42 and the ohmic resistance of the first susceptor 31. As such, l_DC for a probing pulse when the first aerosol-generating article 14 is received in the cavity 41 is reduced to l_A1 (where the “A” stands for “article inserted”), as shown in the fifth pulse of Figure 7. The difference between l_NA and l_A1 is Al_1.

[0207] When the second aerosol-generating article 114 is received in the cavity 41, the DC current feeding the inductive heating arrangement 45 is reduced by a greater amount than when the first aerosol-generating article is received in the cavity 41. This is due to a greater reduction in the conductivity of the total resistive load 54 of the inductive heating arrangement when the second aerosol-generating article 114 is received in the cavity 41 compared to when the first aerosolgenerating article 14 is received in the cavity 41. As such, l_DC for a probing pulse when the second aerosol-generating article 114 is received in the cavity 41 is reduced to l_A2, as shown in the fifth pulse of Figure 8.

[0208] The difference between l_NA and l_A2 is Al_2.

[0209] In this embodiment, a reference value for l_NA, a reference value for the difference between l_NA and l_A1 (i.e. Al_1), and a reference value for the difference between l_NA and l_A2 (i.e. Al_2) are recorded in a memory of the power control electronics 43. The reference value for Al_1 is used as a threshold to determine whether an aerosol-generating article is received in the cavity 41. The difference between l_DC for each probing pulse and the reference value for l_NA is determined, and the determined difference is compared to the stored reference value for Al_1. When the power control electronics 43 determine that l_DC for a probing pulse and the reference value for l_NA is equal to or greater than the stored reference value for A l_1 , the power control electronics 43 are configured to determine that an aerosol-generating article is received in the cavity 41.

[0210] Where the power control electronics 43 determine that the difference between l_DC for a probing pulse and the reference value for l_NA is equal to the stored reference value for Al_1, the control electronics are configured to determine that the first aerosol-generating article is received in the cavity 41.

[0211] Where the power control electronics 43 determine that the difference between l_DC for a probing pulse and the reference value for l_NA is greater than the stored reference value for Al_1, the power control electronics are configured to compare the difference between l_DC for the probing pulse and the reference value for l_NA to the stored reference value for Al_2. Where the power control electronics 43 determine that the difference between l_DC for the probing pulse and the reference value for l_NA is equal to the stored reference value for Al_2, the control electronics are configured to determine that the second aerosol-generating article is received in the cavity 41.

[0212] The reference values for l_NA, Al_1, and Al_2 may be determined and stored in the memory of the power control electronics in a factory calibration procedure. In some embodiments, the reference value for l_NA may be determined using one or more initial current measurements each time the article detection mode is triggered, or the reference value for l_NA may be a moving average of previously measured currents for a plurality of earlier probing pulses.

[0213] In some embodiments, reference value for l_A1 and a reference value for l_A2 may be stored in the memory of the power control electronics 43, and may be compared to current measurements from the current measuring device 55 to determine whether the first aerosol-generating article 14 or the second aerosol-generating article 114 is received in the cavity 41. This may replace the comparisons to Al_1, and Al_2 or may be conducted as an additional confirmation step.

[0214] When the power control electronics 43 determine that the first aerosol-generating article 14 is received in the cavity 41 , the power control electronics 43 are configured to supply power from the DC power supply 44 to the inductive heating arrangement 45 in a first heating profile, which in this embodiment is a puff-actuated heating profile that is optimised for heating the first aerosol-forming substrate 26.

[0215] When the power control electronics 43 determine that the second aerosol-generating article 114 is received in the cavity 41, the power control electronics 43 are configured to supply power from the DC power supply 44 to the inductive heating arrangement 45 in a second heating profile, which in this embodiment is a continuous heating profile that is optimised for heating the second aerosol-forming substrate 126.

[0216] It will be appreciated that the above described examples are exemplary, and other embodiments with different features are envisaged in this disclosure. For example, it is envisaged that in some embodiments the litz wire of the inductor coil 42 may have a different number of individual wires, and may have a different form, such as a rectangular cross-sectional shape. It is also envisaged that in some embodiments, the inductor coil 42 may have a different form, such as a flat coil, and the aerosol-generating device 12 may be provided with more than one inductor coil 42. It is also envisaged that in some embodiments, the power control electronics comprise a puff sensor, such as an airflow sensor or a pressure sensor, which may be used by the power control electronics to determine when a user is taking a puff on the aerosol-generating system. It is also envisaged that the article detection mode may be triggered, for example, by extracting the aerosolgenerating device 12 from a power charging unit. For this, the aerosol-generating device 12 may be configured to detect the extraction of the device from a power charging unit.

[0217] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 10 percent (10%) of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

CLAIMS1. An aerosol-generating device comprising: a cavity, wherein the cavity is configured to: removably receive at least a portion of a first aerosol-generating article, the first aerosol-generating article comprising a first susceptor, and a first aerosol-forming substrate; and removably receive at least a portion of a second aerosol-generating article, separately from the first aerosol-generating article, the second aerosol-generating article comprising a second susceptor, and a second aerosol-forming substrate, the second aerosol-forming substrate being different from the first aerosol-forming substrate; a DC power supply; an inductive heating arrangement connected to the DC power supply, the inductive heating arrangement comprising an inductor coil comprising a litz wire, wherein the inductor coil is arranged to generate an alternating magnetic field in the cavity to heat a susceptor in a portion of an aerosolgenerating article received in the cavity; and power control electronics, wherein the power control electronics are configured to: control the supply of power from the DC power supply to the inductive heating arrangement in a first heating profile to generate an alternating magnetic field in the cavity that causes heating of the first susceptor of the first aerosol-generating article when the first aerosol-generating article is received in the cavity; and control the supply of power from the DC power supply to the inductive heating arrangement in a second heating profile, different to the first heating profile, to generate an alternating magnetic field in the cavity that causes heating of the second susceptor of the second aerosol-generating article when the second aerosol-generating article is received in the cavity.

2. An aerosol-generating device according to claim 1 , wherein the litz wire comprises between 1000 and 4000 individual wires, or around 2000 individual wires.

3. An aerosol-generating device according to claim 1 or claim 2, wherein each individual wire of the litz wire has a diameter of at least 10 microns (pm), or at least 15 microns (pm), or at least 20 microns (pm).

4. An aerosol-generating device according to any one of claims 1 to 3, wherein the litz wire is a multi stage litz wire in which each individual wire of the litz wire is bundled or twisted together in multiple stages, and optionally wherein the multi stage litz wire comprises two, three, four, five, or six bundling stages.

5. An aerosol-generating device according to any one of claims 1 to 4, wherein the litz wire has a length of lay of between about 10 millimetres (mm) and about 20 millimetres (mm), or between about 12 millimetres or about 18 millimetres (mm), or about 16 millimetres (mm).

6. An aerosol-generating device according to any one of claims 1 to 5, wherein the inductor coil circumscribes the cavity, and optionally wherein the inductor coil is a cylindrical coil.

7. An aerosol-generating device according to any one of claims 1 to 6, wherein the cavity is configured to: removably receive at least a portion of the first aerosol-generating article, the first aerosol-generating article comprising the first susceptor; and removably receive at least a portion of the second aerosol-generating article, separately from the first aerosol-generating article, the second aerosol-generating article comprising the second susceptor, wherein the second susceptor is different from the first susceptor.

8. An aerosol-generating device according to any one of claims 1 to 7, wherein the power control electronics are configured to control the supply of power to the inductor coil by controlling the supply of an alternating current to the inductor coil, the alternating current having a frequency of between about 100 kilohertz (kHz), and about 30 megahertz (MHz) ), or between 1 megahertz (MHz) and 20 megahertz (MHz), or greater than 5 megahertz (MHz), or between 5 megahertz (5 MHz) and 15 megahertz (15 MHz) or around 6.78 megahertz (MHz).

9. An aerosol-generating device according to any one of claims 1 to 8, wherein the first heating profile is a continuous heating profile, wherein the power control electronics are configured to continuously generates an alternating magnetic field in the cavity that causes continuous heating of the first susceptor of the first aerosol-generating article when the first aerosol-generating article is received in the cavity.

10. An aerosol-generating device according to any one of claims 1 to 9, wherein the power control electronics are configured to detect when a user takes a puff on the aerosol-generating device, and wherein the second heating profile is a puff actuated heating profile, wherein the power control electronics are configured to generate an alternating magnetic field in the cavity that causes heating of the second susceptor of the second aerosol-generating article when the power control electronics detect when a user is taking a puff on the aerosol-generating device, and when the second aerosol-generating article is received in the cavity.

11. An aerosol-generating system comprising: an aerosol-generating device according to any one of claims 1 to 10; a first aerosol-generating article, the first aerosol-generating article comprising a first susceptor, and a first aerosol-forming substrate; and a second aerosol-generating article, the second aerosol-generating article comprising a second aerosol-forming substrate, separately from the first aerosol-generating article, the second aerosol-generating article comprising a second susceptor, and a second aerosol-forming substrate, the second aerosol-forming substrate being different from the first aerosol-forming substrate.

12. An aerosol-generating system according to claim 11 , wherein the first aerosol-forming substrate is a liquid aerosol-forming substrate, and wherein the second aerosol-forming substrate is a solid aerosol-forming substrate, and optionally wherein the second aerosol-forming substrate comprises a gathered, crimped sheet of homogenised tobacco material.

13. An aerosol-generating system according to claim 11 or claim 12, wherein at least one of: the size of the second susceptor is different from the size of the first susceptor; and the second susceptor has a different form or shape to the first susceptor, optionally wherein the second susceptor is in the form of a strip, and the first susceptor is in the form of a mesh.

14. An aerosol-generating system according to any one of claims 11 to 13, wherein at least one of: an electrical property of the second susceptor is different to an electrical property of the first susceptor; and a magnetic property of the second susceptor is different to a magnetic property of the first susceptor.

15. An aerosol-generating system according to any one of claims 11 to 14, wherein the electrical resistance of the second susceptor at room temperature is different to the electrical resistance of the first susceptor at room temperature.

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