Induction heating device with gas permeable segmented induction heating element

Abstract

The present invention provides an induction heating element (10) for an aerosol generating system, an induction heating device for an aerosol generating system, an aerosol generating device with an induction heating device, and an aerosol generating system with an aerosol generating device having an induction heating device. The induction heating element (10) comprises: a cavity (20) for receiving an aerosol-forming substrate to be heated by the induction heating element (10); a first susceptor (12); a second susceptor (14); and an intermediate element (16) disposed between the first susceptor (12) and the second susceptor (14), the intermediate element (16) being air-permeable, wherein the intermediate element (16) comprises at least one of the following: a thermal insulation material for thermally insulating the first susceptor (12) from the second susceptor (14); and an electrical insulation material for electrically insulating the first susceptor (12) from the second susceptor (14).

Description

Technical Field

[0001] The present disclosure relates to an induction heating element for an aerosol generating system, an induction heating device for an aerosol generating system, an aerosol generating device with an induction heating device, and an aerosol generating system with an aerosol generating device with an induction heating device. Background Art

[0002] A number of electrically powered aerosol-generating systems have been proposed in the art, in which an aerosol-generating device with an electric heater is used to heat an aerosol-forming substrate, such as a tobacco filter segment. One purpose of such aerosol-generating systems is to reduce the known types of harmful smoke constituents produced by the combustion and pyrolytic degradation of tobacco in conventional cigarettes. Typically, the aerosol-generating substrate is provided as part of an aerosol-generating article, which is inserted into the cavity of the aerosol-generating device. In some known systems, in order to heat the aerosol-forming substrate to a temperature capable of releasing volatile components that can form an aerosol, a resistive heating element (such as a heating blade) is inserted into or around the aerosol-forming substrate when the article is received in the aerosol-generating device. In other aerosol-generating systems, an induction heater is used rather than a resistive heating element. The induction heater typically comprises an inductor coil forming part of the aerosol-generating device, and a susceptor arranged so that it is thermally adjacent to the aerosol-forming substrate. The inductor generates a varying magnetic field to generate eddy currents and hysteresis losses in the susceptor, causing the susceptor to heat up, thereby heating the aerosol-forming substrate. Induction heating allows an aerosol to be generated without exposing the heater to the aerosol-generating article. This may improve the ease with which the heater can be cleaned.

[0003] Some known aerosol-generating devices include more than one inductor coil, each arranged to heat a different portion of a susceptor. Such aerosol-generating devices can be used to heat different portions of an aerosol-generating article at different times or at different temperatures. However, such aerosol-generating devices may have difficulty heating a portion of an aerosol-generating article without indirectly heating adjacent portions of the aerosol-generating article.

[0004] It would be desirable to provide an aerosol generating device which alleviates or overcomes these problems of known systems. Summary of the Invention

[0005] According to the present disclosure, there is provided an induction heating element for an aerosol generating system.

[0006] The induction heating element may include a first susceptor. The induction heating element may include a second susceptor. The induction heating unit may include an intermediate element disposed between the first susceptor and the second susceptor. The intermediate element may be air permeable.

[0007] Specifically, according to the present disclosure, there is provided an induction heating element for an aerosol generating system, the induction heating element comprising: a first susceptor; a second susceptor; and an intermediate element disposed between the first susceptor and the second susceptor, the intermediate element being air permeable.

[0008] Providing an air permeable intermediate element between the first and second susceptors enables air to be drawn through the inductive heating element at the intermediate element.

[0009] Drawing air through the induction heating element at the intermediate element can provide cooling for the ends of the first and second susceptors adjacent to the intermediate member. Advantageously, cooling the ends of the first and second susceptors adjacent to the intermediate element can facilitate selective heating of the aerosol-forming substrate in the region of the first and second susceptors. When one of the susceptors is heated to a higher temperature than the other, the air-permeable intermediate element can help reduce heat transfer from the higher-temperature susceptor to the lower-temperature susceptor by cooling the adjacent ends of the susceptors as air is drawn through the intermediate element.

[0010] According to the present disclosure, there is provided an induction heating device for an aerosol generating system.

[0011] An induction heating device may include an induction heating element. The induction heating element may include: a first susceptor; a second susceptor; and an intermediate element disposed between the first and second susceptors. The intermediate element may be air-permeable. The induction heating device may also include a first inductor coil. The induction heating device may also include a second inductor coil. The first inductor coil may be arranged relative to the induction heating element such that a varying current supplied to the first inductor coil generates a varying magnetic field that heats the first susceptor of the induction heating element. The second inductor coil may be arranged relative to the induction heating element such that a varying current supplied to the second inductor coil generates a varying magnetic field that heats the second susceptor of the induction heating element.

[0012] Specifically, according to the present disclosure, an induction heating device for an aerosol generating system is provided, comprising an induction heating element, a first inductor coil, and a second inductor coil. The induction heating element comprises a first susceptor, a second susceptor, and an intermediate element disposed between the first and second susceptors, the intermediate element being air-permeable. The first inductor coil is arranged relative to the induction heating element such that a varying current supplied to the first inductor coil generates a varying magnetic field that heats the first susceptor of the induction heating element. The second inductor coil is arranged relative to the induction heating element such that a varying current supplied to the second inductor coil generates a varying magnetic field that heats the second susceptor of the induction heating element.

[0013] Providing an induction heating device having a first induction coil arranged to heat a first susceptor of the induction heating element and a second induction coil arranged to heat a second susceptor of the induction heating element enables selective heating of the first and second susceptors. Such selective heating enables the induction heating device to heat different portions of the aerosol-forming substrate at different times and may enable one of the susceptors to be heated to a different temperature than another susceptor.

[0014] According to the present disclosure, there is provided an aerosol generating device comprising an induction heating device.

[0015] An induction heating device may include an induction heating element. The induction heating element may include a first susceptor; a second susceptor; and an intermediate element disposed between the first and second susceptors. The intermediate element may be air-permeable. The induction heating device may also include a first inductor coil. The induction heating device may also include a second inductor coil. The first inductor coil may be arranged relative to the induction heating element such that a varying current supplied to the first inductor coil generates a varying magnetic field that heats the first susceptor of the induction heating element. The second inductor coil may be arranged relative to the induction heating element such that a varying current supplied to the second inductor coil generates a varying magnetic field that heats the second susceptor of the induction heating element.

[0016] Specifically, according to the present disclosure, an aerosol-generating device is provided, comprising a device housing defining a device cavity for receiving an aerosol-forming substrate. The aerosol-generating device also includes an induction heating device, the induction heating device including an induction heating element, the induction heating element comprising: a first susceptor disposed around a first portion of the device cavity; a second susceptor disposed around a second portion of the device cavity; and an intermediate element disposed around an intermediate portion of the device cavity between the first and second portions of the device cavity, the intermediate element being air-permeable. The aerosol-generating device also includes: a first inductor coil disposed around at least a portion of the first susceptor and the first portion of the device cavity; a second inductor coil disposed around at least a portion of the second susceptor and the second portion of the device cavity; and a power source connected to the induction heating device and configured to supply a varying current to the first inductor coil and the second inductor coil. When the varying current is supplied to the first inductor coil, the first inductor coil generates a varying magnetic field that heats the first susceptor. When the varying current is supplied to the second inductor coil, the second inductor coil generates a varying magnetic field that heats the second susceptor.

[0017] In addition to enabling efficient selective heating of the first portion of the device cavity and the second portion of the device cavity, the air permeable intermediate element can also enable air to be drawn into the device cavity between the first portion of the device cavity and the second portion of the device cavity. Thus, the air permeable intermediate element can enable air to be supplied directly to the first portion of the aerosol-forming substrate received in the first portion of the device cavity without the air first passing through the second portion of the aerosol-forming substrate received in the second portion of the device cavity. Similarly, the air permeable intermediate element can enable air to be supplied directly to the second portion of the aerosol-forming substrate received in the second portion of the device cavity without the air first passing through the first portion of the aerosol-forming substrate received in the first portion of the device cavity. Advantageously, supplying air directly to a portion of the aerosol-forming substrate received in a portion of the device cavity can provide improved control over the properties of the aerosol generated by the aerosol-forming substrate when the portion of the aerosol-forming substrate is heated by one of the susceptors.

[0018] According to the present disclosure, an aerosol-generating system is provided. The aerosol-generating system also includes an aerosol-generating article including an aerosol-forming substrate and an aerosol-generating device configured to receive at least a portion of the aerosol-generating article. The aerosol-generating article may include a first aerosol-forming substrate and a second aerosol-forming substrate. The aerosol-generating device may include an induction heating device. The induction heating device may include an induction heating element. The induction heating element may include a first susceptor; a second susceptor; and an intermediate element disposed between the first and second susceptors. The intermediate element may be air-permeable. The induction heating device may also include a first inductor coil. The induction heating device may also include a second inductor coil. The first inductor coil may be arranged relative to the induction heating element such that a varying current supplied to the first inductor coil generates a varying magnetic field that heats the first susceptor of the induction heating element. The second inductor coil may be arranged relative to the induction heating element such that a varying current supplied to the second inductor coil generates a varying magnetic field that heats the second susceptor of the induction heating element. The induction heating device may be arranged such that when the aerosol-generating article is received in the aerosol-generating device, the first susceptor is positioned to heat a first aerosol-forming substrate of the aerosol-generating article. The induction heating device may be arranged such that when the aerosol-generating article is received in the aerosol-generating device, the second susceptor is positioned to heat a second aerosol-forming substrate of the aerosol-generating article.

[0019] As used herein, the term "aerosol-forming substrate" relates to a substrate capable of releasing volatile compounds that can form an aerosol. Such volatile compounds can be released by heating the aerosol-forming substrate. The aerosol-forming substrate is part of an aerosol-generating article.

[0020] As used herein, the term "aerosol-generating article" refers to an article comprising an aerosol-forming substrate capable of releasing volatile compounds that can form an aerosol. For example, an aerosol-generating article can be an article that generates an aerosol that can be directly inhaled by a user drawing or puffing on a mouthpiece at the proximal or user end of the system. The aerosol-generating article can be disposable. An article comprising an aerosol-forming substrate comprising tobacco can be referred to as a tobacco stick.

[0021] As used herein, the term "aerosol-generating device" refers to a device that interacts with an aerosol-forming substrate to generate an aerosol.

[0022] As used herein, the term "aerosol-generating system" refers to the combination of an aerosol-generating device and an aerosol-generating article. In an aerosol-generating system, the aerosol-generating article and the aerosol-generating device cooperate to generate a respirable aerosol.

[0023] As used herein, the term "varying current" includes any current that varies over time to generate a varying magnetic field. The term "varying current" is intended to include alternating current. In the case where the varying current is an alternating current, the alternating current generates an alternating magnetic field.

[0024] As used herein, the term "length" refers to the principal dimension in the longitudinal direction of an aerosol-generating device, or an aerosol-generating article, or a component of an aerosol-generating device or an aerosol-generating article.

[0025] As used herein, the term "width" refers to the major dimension in the transverse direction of an aerosol-generating device, or an aerosol-generating article, or a component of an aerosol-generating device or an aerosol-generating article, at a particular location along its length. The term "thickness" refers to the dimension in the transverse direction perpendicular to the width.

[0026] As used herein, the term "cross-section" is used to describe a cross-section of an aerosol-generating device, or an aerosol-generating article, or a component of an aerosol-generating device or an aerosol-generating article, at a particular position along its length, in a direction perpendicular to the longitudinal direction.

[0027] As used herein, the term "proximal" refers to the user end or mouth end of an aerosol-generating device or an aerosol-generating article. The proximal end of a component of an aerosol-generating device or an aerosol-generating article is the end of the component closest to the user end or mouth end of the aerosol-generating device or an aerosol-generating article. As used herein, the term "distal" refers to the end opposite the proximal end.

[0028] According to the present disclosure, there is provided an induction heating element for an aerosol generating system.

[0029] In some embodiments, the inductive heating element may comprise an internal heating element.As used herein, the term "internal heating element" refers to a heating element configured to be inserted into an aerosol-forming substrate.

[0030] The internal heating element is preferably configured to be insertable into the aerosol-forming substrate. The internal heating element may be in the form of a blade. The internal heating element may be in the form of a needle. The internal heating element may be in the form of a cone. Where the aerosol-generating device comprises a device cavity for receiving the aerosol-forming substrate, preferably the internal heating element extends into the device cavity.

[0031] In some embodiments, the induction heating element may comprise an external heating element.As used herein, the term "external heating element" refers to a heating element configured to heat the outer surface of the aerosol-forming substrate.

[0032] The external heating element is preferably configured to at least partially surround the aerosol-forming substrate when the aerosol-forming substrate is received by the aerosol-generating device.

[0033] In some embodiments, the induction heating device includes at least one internal heating element and at least one external heating element.

[0034] The induction heating element may include a cavity for receiving the aerosol-forming substrate. Specifically, where the induction heating element is an external heating element, the induction heating element may include a cavity for receiving the aerosol-forming substrate. The induction heating element may be configured to heat the outer surface of the aerosol-forming substrate when the aerosol-forming substrate is received in the induction heating element cavity.

[0035] The induction heating element may include an outer side and an inner side opposite the outer side. The inner side may at least partially define an induction heating element cavity for receiving the aerosol-forming substrate. The intermediate element may be configured to permit air to flow from the outer side to the inner side. The intermediate element may include one or more air passages configured to permit air to flow from the outer side to the inner side. The one or more air passages may extend from the outer side to the inner side of the induction heating element.

[0036] In some preferred embodiments, the induction heating element is a tubular induction heating element. The inner surface of the tubular induction heating element may define the induction heating element cavity. The first susceptor may be a tubular susceptor that defines a portion of the induction heating element cavity. The second susceptor may be a tubular susceptor that defines a portion of the induction heating element cavity. The intermediate element may be a tubular intermediate element that defines a portion of the induction heating element cavity.

[0037] In embodiments where the aerosol-generating device comprises a device cavity for receiving the aerosol-forming substrate, the induction heating element may at least partially define the device cavity.The induction heating element cavity may be aligned with the device cavity.

[0038] The induction heating element includes a first susceptor and a second susceptor.

[0039] As used herein, the term "susceptor" refers to an element comprising a material capable of converting electromagnetic energy into heat. When the susceptor is placed in a varying magnetic field, the susceptor is heated. The heating of the susceptor may be the result of at least one of hysteresis losses and eddy currents induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material.

[0040] The susceptor may comprise any suitable material. The susceptor may be formed of any material that can be inductively heated to a temperature sufficient to aerosolize the aerosol-forming substrate. Preferred susceptors may be heated to a temperature exceeding about 250 degrees Celsius. Preferred susceptors may be formed of electrically conductive materials. As used herein, "electrically conductive" means having a conductivity of less than or equal to 1 x 10 at 20 degrees Celsius. -4 The preferred susceptor may be formed of a thermally conductive material. As used herein, the term "thermally conductive material" is used to describe a material having a thermal conductivity of at least 10 watts per meter Kelvin (W / (mK)) at 23 degrees Celsius and 50% relative humidity as measured using the modified transient planar heat source (MTPS) method.

[0041] Suitable materials for the susceptor include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Some preferred susceptors include metal or carbon. Some preferred susceptors include ferromagnetic materials, such as ferritic iron, ferromagnetic alloys (such as ferromagnetic steel or stainless steel), ferromagnetic particles, and ferrites. Some preferred susceptors are composed of ferromagnetic materials. Suitable susceptors may include aluminum. Suitable susceptors may be composed of aluminum. The susceptor may include at least about 5%, at least about 20%, at least about 50%, or at least about 90% ferromagnetic or paramagnetic material.

[0042] Preferably, the susceptor is formed of a material that is substantially impermeable to air. In other words, preferably, the susceptor is formed of a material that is impermeable to air.

[0043] The susceptor of the induction heating element can have any suitable form. For example, the susceptor can be elongated. The susceptor can have any suitable cross-section. For example, the susceptor can have a circular, oval, square, rectangular, triangular, or other polygonal cross-section. The susceptor can be tubular. A tubular susceptor includes an annular body defining an inner cavity. The susceptor cavity can be configured to receive the aerosol-forming substrate. The susceptor cavity can be an open cavity. The susceptor cavity can be open at one end. The susceptor cavity can be open at both ends.

[0044] In the case where the susceptor is a tubular susceptor having a cavity for receiving the aerosol-forming substrate that is open at one or both ends, the susceptor is preferably substantially gas-impermeable from the outer surface to the inner surface defining the inner cavity. In other words, the susceptor is preferably substantially impermeable to gas passing through the sidewalls of the susceptor.

[0045] In some embodiments, each susceptor is substantially identical. For example, the second susceptor can be substantially identical to the first susceptor. Each susceptor can be formed from the same material. Each susceptor can have substantially the same shape and size. Making each susceptor substantially identical to the other susceptors can allow each susceptor to be heated to substantially the same temperature and at substantially the same rate when exposed to a given varying magnetic field.

[0046] In some embodiments, the second susceptor differs from the first susceptor in at least one characteristic. The second susceptor may be formed of a different material than the first susceptor. The second susceptor may have a different shape and size than the first susceptor. The second susceptor may have a length that is longer than the length of the first susceptor. Making each susceptor different from the other susceptors can allow each susceptor to be tailored to provide optimal heat for different aerosol-forming substrates.

[0047] In one example, a first aerosol-forming substrate may need to be heated to a first temperature in order to generate a first aerosol having desired properties, and a second aerosol-forming substrate may need to be heated to a second temperature different from the first temperature in order to generate a second aerosol having desired properties. In this example, the first susceptor may be formed of a first material suitable for heating the first aerosol-forming substrate to the first temperature, and the second susceptor may be formed of a second material different from the first material suitable for heating the second aerosol-forming substrate to the second temperature.

[0048] In another example, an aerosol-generating article may include a first aerosol-forming substrate having a first length and a second aerosol-forming substrate having a second length different from the first length, such that heating the second aerosol-forming substrate generates a different amount of aerosol than heating the first aerosol-forming substrate. In this embodiment, the first susceptor may have a length substantially equal to the first length, and the second susceptor may have a length substantially equal to the second length.

[0049] In some preferred embodiments, the first susceptor is an elongated tubular susceptor and the second susceptor is an elongated tubular susceptor. In these preferred embodiments, the first susceptor and the second susceptor can be substantially aligned. In other words, the first susceptor and the second susceptor can be coaxially aligned.

[0050] The induction heating element may include any suitable number of susceptors. The induction heating element may include a plurality of susceptors. The induction heating element may include at least two susceptors. For example, the induction heating element may include three, four, five, or six susceptors. Where the induction heating element includes more than two susceptors, an intermediate element may be disposed between each adjacent pair of susceptors.

[0051] In some preferred embodiments, the susceptor can include a susceptor layer disposed on a support. Each of the first and second susceptors can be formed from a support and a susceptor layer. Arranging the susceptor in a varying magnetic field induces eddy currents near the susceptor surface, an effect known as the skin effect. Consequently, the susceptor can be formed from a relatively thin layer of susceptor material while ensuring that the susceptor is effectively heated in the presence of a varying magnetic field. Fabricating the susceptor from a support and a relatively thin susceptor layer can facilitate the manufacture of simple, inexpensive, and robust aerosol-generating articles.

[0052] The support may be formed from a material that is not susceptible to induction heating. Advantageously, this may reduce heating of the surface of the susceptor that is not in contact with the aerosol-forming substrate, wherein the surface of the support forms the surface of the susceptor that is not in contact with the aerosol-forming substrate.

[0053] The support may comprise an electrically insulating material. As used herein, "electrically insulating" means having a resistance of at least 1 x 10 4 The resistivity of a material is measured in ohm-meters (Ω.m).

[0054] The support may include a thermally insulating material for thermally insulating the first susceptor from the second susceptor. As used herein, the term "thermally insulating material" is used to describe a material having a bulk thermal conductivity of less than or equal to about 40 watts per meter Kelvin (W / (mK)) at 23 degrees Celsius and 50% relative humidity as measured using a modified transient plane source (MTPS) method.

[0055] Forming the support from a thermally insulating material may provide a thermally insulating barrier between the susceptor layer and other components of the induction heating apparatus, such as the inductor coils defining the induction heating element. Advantageously, this may reduce heat transfer between the susceptor and other components of the induction heating system.

[0056] In the case where the susceptor is a tubular susceptor comprising a cavity for receiving the aerosol-forming substrate, the support may be a tubular support, and the susceptor layer may be provided on the inner surface of the tubular support. Providing the susceptor layer on the inner surface of the support may position the susceptor layer in the cavity of the induction heating element adjacent to the aerosol-forming substrate to improve heat transfer between the susceptor layer and the aerosol-forming substrate.

[0057] In some preferred embodiments, the first susceptor comprises a tubular support formed of a thermally insulating material and a susceptor layer on the inner surface of the tubular support. In some preferred embodiments, the second susceptor comprises a tubular support formed of a thermally insulating material and a susceptor layer on the inner surface of the tubular support.

[0058] The susceptor may be provided with a protective outer layer, such as a protective ceramic layer or a protective glass layer. The protective outer layer may improve the durability of the susceptor and facilitate cleaning of the susceptor. The protective outer layer may substantially surround the susceptor. The susceptor may include a protective coating formed from glass, ceramic, or an inert metal.

[0059] The induction heating element includes an intermediate element disposed between a first susceptor and a second susceptor.

[0060] The intermediate element may have any suitable form. The intermediate element may have any suitable cross-section. For example, the intermediate element may have a circular, oval, square, rectangular, triangular, or other polygonal cross-section. The intermediate element may be tubular. The tubular intermediate element includes an annular body defining an inner cavity. The intermediate element may be configured to allow gas to permeate from the outside of the intermediate element into the inner cavity. The intermediate element cavity may be configured to receive a portion of the aerosol-generating article. The intermediate element cavity may be an open cavity. The intermediate element cavity may be open at one end. The intermediate element cavity may be open at both ends.

[0061] In some preferred embodiments, the first and second susceptors are tubular susceptors, and the intermediate element is a tubular intermediate element. In these embodiments, the first tubular susceptor, the second tubular susceptor, and the intermediate element can be substantially aligned. The first tubular susceptor, the intermediate element, and the second tubular susceptor can be arranged end-to-end in the form of a tubular rod. The inner lumens of the first tubular susceptor, the intermediate element, and the second tubular susceptor can be substantially aligned. The inner lumens of the first tubular susceptor, the intermediate element, and the second tubular susceptor can define an induction heating element cavity.

[0062] The intermediate element may be formed from any suitable material.

[0063] In some embodiments, the intermediate element is formed of the same material as the first susceptor. In some embodiments, the intermediate element is formed of the same material as the second susceptor. In some embodiments, the first susceptor, the second susceptor, and the intermediate element are formed of the same material.

[0064] In some preferred embodiments, the intermediate element is formed of a different material than the first and second susceptors.

[0065] The intermediate element may comprise a thermally insulating material for thermally insulating the first susceptor from the second susceptor.

[0066] The intermediate element may comprise an electrically insulating material for electrically insulating the first susceptor from the second susceptor.

[0067] The intermediate element may include at least one of: a thermally insulating material for thermally insulating the first susceptor from the second susceptor; and an electrically insulating material for electrically insulating the first susceptor from the second susceptor. In some preferred embodiments, the intermediate element includes a thermally insulating material for thermally insulating the first susceptor from the second susceptor, and an electrically insulating material for electrically insulating the first susceptor from the second susceptor.

[0068] Particularly suitable materials for the intermediate element may include polymeric materials such as polyetheretherketone (PEEK), liquid crystal polymers such as ), certain cements, glass and ceramic materials (such as zirconium dioxide (ZrO2), silicon nitride (Si3N4) and aluminum oxide (Al2O3)).

[0069] The intermediate element is gas-permeable. In other words, the intermediate element is configured to allow gas to permeate through the intermediate element. Typically, the intermediate element is configured to allow gas to permeate from one side of the intermediate element to the other side of the intermediate element. The intermediate element may include an outer side and an inner side opposite the outer side. The intermediate element may be configured to allow gas to permeate from the outer side to the inner side.

[0070] In some embodiments, the intermediate element includes an air passage configured to allow air to pass through the intermediate element. In these embodiments, the intermediate element may not need to be formed from a breathable material. Therefore, in some embodiments, the intermediate element is formed from an airtight material and includes an air passage configured to allow air to pass through the intermediate element. The intermediate element may include a plurality of air passages. The intermediate element may include any suitable number of air passages, for example, two, three, four, five or six air passages. When the intermediate element includes a plurality of air passages, the air passages may be regularly spaced apart on the intermediate element.

[0071] In the case where the intermediate element is a tubular intermediate element defining an inner lumen, the intermediate element may include an air passage configured to allow air to flow from an outer surface of the intermediate element into the inner lumen. The intermediate element may include an air passage extending from the outer surface to the inner surface. In the case where the tubular intermediate element includes a plurality of air passages, the air passages may be regularly spaced around the circumference of the tubular intermediate element.

[0072] In some embodiments, the intermediate element may comprise a porous material that is breathable. In these embodiments, the porosity of the material can provide gas permeability. In other words, the pores of the porous material can be of sufficient size and interconnected to allow gas to permeate through the porous material. Such porous materials may not require dedicated air passages to be provided through the porous material in order for the porous material to be breathable. However, it is also contemplated that in some embodiments, the intermediate element may comprise a porous material having at least one air passage.

[0073] The intermediate element may include a first porous material and a second porous material. The second porous material may have a higher porosity than the first porous material. In these embodiments, the increased porosity of the second porous material relative to the first porous material may promote airflow in the direction of the second porous material.

[0074] The intermediate element may include a distal end adjacent to the first susceptor and a proximal end opposite the distal end and adjacent to the second susceptor. The first porous material may be arranged toward the distal end of the intermediate element. The second porous material may be arranged toward the proximal end of the intermediate element. Thus, the arrangement of the first and second porous materials may promote airflow in the direction of the proximal end of the intermediate element, and in the direction of the second porous material and the second susceptor.

[0075] In some preferred embodiments, the porosity of the second porous material, as measured by mercury intrusion porosimetry according to ISO 15901-1:2005, is at least 1.5 times the porosity of the first porous material. More preferably, the porosity of the second porous material, as measured by mercury intrusion porosimetry, is at least twice the porosity of the first porous material.

[0076] In certain preferred embodiments, the second porous material may have a porosity of between about 20% and about 50% as measured by mercury intrusion porosimetry according to ISO 15901-1:2005, and the first porous material may have a porosity of between about 5% and about 35% as measured by mercury intrusion porosimetry according to ISO 15901-1:2005.

[0077] In certain embodiments, the porosity of the second porous material, as measured by mercury intrusion porosimetry according to ISO 15901-1:2005, may be between about 1.5 and about 10 times the porosity of the first porous material, preferably between about 1.5 and about 5 times the porosity of the first porous material. In other embodiments, the porosity of the second porous material, as measured by mercury intrusion porosimetry according to ISO 15901-1:2005, may be between about 2 and about 10 times the porosity of the first porous material, preferably between about 2 and about 5 times the porosity of the first porous material.

[0078] In some embodiments, the intermediate element includes a third porous material. The third porous material can be arranged between the first porous material and the second porous material. The third porous material can have a higher porosity than the first porous material. The third porous material can have a lower porosity than the second porous material.

[0079] The induction heating element may be included in an induction heating device.

[0080] The induction heating device further includes a first inductor coil and a second inductor coil.

[0081] The first inductor coil is configured such that a varying current supplied thereto generates a varying magnetic field. The first inductor coil is arranged relative to the induction heating element such that a varying current supplied thereto generates a varying magnetic field that heats a first susceptor of the induction heating element.

[0082] The second inductor coil is configured such that a varying current supplied thereto generates a varying magnetic field. The second inductor coil is arranged relative to the induction heating element such that a varying current supplied thereto generates a varying magnetic field that heats the second susceptor of the induction heating element.

[0083] The inductor coil may have any suitable form. For example, the inductor coil may be a flat inductor coil. The flat inductor coil may be wound helically in a substantially flat plane. Preferably, the inductor coil is a tubular inductor coil defining an inner cavity. Typically, the tubular inductor coil is wound helically around an axis. The inductor coil may be elongated. Particularly preferably, the inductor coil may be an elongated tubular inductor coil. The inductor coil may have any suitable cross-section. For example, the inductor coil may have a circular, oval, square, rectangular, triangular, or other polygonal cross-section.

[0084] The inductor coil may be formed from any suitable material. The inductor coil is formed from a conductive material. Preferably, the inductor coil is formed from a metal or a metal alloy.

[0085] When the inductor coil is a tubular inductor coil, preferably, a portion of the induction heating element is disposed within the lumen of the inductor coil. Particularly preferably, the first inductor coil is a tubular inductor coil, and at least a portion of the first susceptor is disposed within the lumen of the first inductor coil. The length of the first tubular inductor coil can be substantially similar to the length of the first susceptor. Particularly preferably, the second inductor coil is a tubular inductor coil, and at least a portion of the second susceptor is disposed within the lumen of the second inductor coil. The length of the second tubular inductor coil can be substantially similar to the length of the second susceptor.

[0086] In some embodiments, the second inductor coil is substantially identical to the first inductor coil. In other words, the first inductor coil and the second inductor coil have the same shape, size, and number of turns. Particularly preferably, in embodiments where the second inductor coil is substantially identical to the first inductor coil, the second inductor coil is substantially identical to the first inductor coil.

[0087] In some embodiments, the second inductor coil is different from the first inductor coil. For example, the second inductor coil may have a different length, number of turns, or cross-section than the first inductor coil. Particularly preferably, in embodiments where the second susceptor is different from the first susceptor, the second inductor coil is different from the first inductor coil.

[0088] The first inductor coil and the second inductor coil may be arranged in any suitable arrangement. It is particularly preferred that the first inductor coil and the second inductor coil are coaxially aligned along an axis. Where the first inductor coil and the second inductor coil are elongated tubular inductor coils, the first inductor coil and the second inductor coil may be coaxially aligned along the longitudinal axis such that the inner lumens of the coils are aligned along the longitudinal axis.

[0089] The induction heating device may include any suitable number of induction coils. The induction heating element may include a plurality of induction coils. The induction heating device may include at least two induction coils. Preferably, the number of induction coils in the induction heating device is the same as the number of susceptors in the induction heating element. The number of induction coils in the induction heating device may be different from the number of susceptors in the induction heating element. Where the number of induction coils is the same as the number of susceptors, each induction coil is preferably disposed around a susceptor. Particularly preferably, each induction coil extends substantially the length of the susceptor around which the induction coil is disposed.

[0090] The induction heating element may include a flux concentrator. The flux concentrator may be disposed around the induction coil of the induction heating device. The flux concentrator is configured to distort a changing magnetic field generated by the induction coil toward the induction heating element.

[0091] Advantageously, the flux concentrator can concentrate the magnetic field at the induction heating element by twisting the magnetic field toward the induction heating element. This can improve the efficiency of the induction heating device compared to an embodiment in which the flux concentrator is not provided. As used herein, the phrase "concentrating the magnetic field" means twisting the magnetic field so that the magnetic energy density of the magnetic field is increased at the location where the magnetic field is "concentrated."

[0092] As used herein, the term "flux concentrator" refers to a component with high relative magnetic permeability that is used to concentrate and guide the magnetic field or magnetic field lines generated by the inductor coil. As used herein, the term "relative magnetic permeability" refers to the ratio of the magnetic permeability of a material or medium such as a flux concentrator to the magnetic permeability of free space "μ0", where μ0 is 4π×10 -7 Newton per ampere squared (NA -2 ).

[0093] As used herein, the term "high relative permeability" refers to a relative permeability at 25 degrees Celsius of at least 5, for example at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 80, or at least 100. These example values ​​preferably refer to values ​​of relative permeability for frequencies between 6 and 8 MHz and a temperature of 25 degrees Celsius.

[0094] The flux concentrator may be formed from any suitable material or combination of materials. Preferably, the flux concentrator comprises a ferromagnetic material, such as a ferrite material, ferrite powder held in a binder, or any other suitable material containing a ferrite material, such as ferromagnetic iron, ferromagnetic steel or stainless steel.

[0095] In some embodiments, the induction heating device includes a flux concentrator disposed around the first inductor coil and the second inductor coil. In these embodiments, the flux concentrator is configured to distort the changing magnetic field generated by the first inductor coil toward the first susceptor of the induction heating element, and to distort the changing magnetic field generated by the second inductor coil toward the second susceptor of the induction heating element.

[0096] In some of these embodiments, a portion of the flux concentrator extends into an intermediate element between the first and second susceptors. Extending a portion of the flux concentrator into the intermediate element between the first and second susceptors can further distort the magnetic field generated by the first inductor coil and the magnetic field generated by the second inductor coil. This further distortion can cause the magnetic field generated by the first inductor coil to be further concentrated toward the first susceptor, and the magnetic field generated by the second inductor coil to be further concentrated toward the second susceptor. This can further improve the efficiency of the induction heating device.

[0097] In some embodiments, the induction heating device includes multiple flux concentrators. In some preferred embodiments, a separate flux concentrator is disposed around each inductor coil. Providing a dedicated flux concentrator for each inductor coil allows the flux concentrator to be optimally configured to distort the magnetic field generated by the inductor coil. This arrangement also allows the induction heating device to be formed from modular induction heating units. Each induction heating unit can include an inductor coil and a flux concentrator. Providing modular induction heating units can facilitate standardized manufacturing of the induction heating device and enable individual units to be removed and replaced.

[0098] In some preferred embodiments, the induction heating device includes: a first flux concentrator disposed around a first inductor coil, the first flux concentrator configured to distort a changing magnetic field generated by the first inductor coil toward the first susceptor; and a second flux concentrator disposed around a second inductor coil, the second flux concentrator configured to distort a changing magnetic field generated by the second inductor coil toward the second susceptor.

[0099] In these preferred embodiments, a portion of the first flux concentrator may extend into an intermediate element between the first and second susceptors. In these preferred embodiments, a portion of the second flux concentrator may extend into an intermediate element between the first and second susceptors. Extending a portion of the flux concentrator into the intermediate element between the susceptors may enable the flux concentrator to further distort the magnetic field generated by the inductor coil toward the susceptors.

[0100] The induction heating device may further include an induction heating device housing. The housing may hold the induction heating element, the induction coil, and the flux concentrator together. This may help stabilize the relative arrangement of the components of the induction heating device and improve the coupling between the components. Preferably, the induction heating device housing is formed from an electrically insulating material.

[0101] Where the induction heating device includes separate induction heating units each including an induction coil and a flux concentrator, each induction heating unit may include an induction heating unit housing. The induction heating unit housing may hold the components of the induction heating unit together and improve coupling between the components. Preferably, the induction heating unit housing is formed from an electrically insulating material.

[0102] The induction heating device may be included in the aerosol generating device.

[0103] The aerosol generating device may include a power source. The power source may be any suitable type of power source. The power source may be a DC power source. In some preferred embodiments, the power source is a battery, such as a rechargeable lithium-ion battery. The power source may be another form of charge storage device, such as a capacitor. The power source may need to be recharged. The power source may have a capacity that allows sufficient energy to be stored for one or more uses of the device. For example, the power source may have sufficient capacity to allow continuous aerosol generation for a period of approximately six minutes, corresponding to the typical time spent smoking a conventional cigarette, or for a period of multiple six minutes. In another example, the power source may have sufficient capacity to allow a predetermined number of uses of the device or discontinuous activation. In one embodiment, the power source is a DC power source having 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 ampere to about 10 amperes (corresponding to a DC supply between about 2.5 watts and about 45 watts).

[0104] The aerosol generating device may include a controller connected to the induction heating device and a power supply. Specifically, the aerosol generating device may include a controller connected to the first inductor coil, the second inductor coil and the power supply. The controller is configured to control the supply of power from the power supply to the induction heating device. The controller may include a microprocessor, which may be a programmable microprocessor, a microcontroller or an application specific integrated circuit (ASIC) or other circuit capable of providing control. The controller may include other electronic components. The controller may be configured to regulate the current supply to the induction heating device. The current may be continuously supplied to the induction heating device after the aerosol generating device is activated, or may be supplied intermittently, such as on a puff-by-puff basis.

[0105] The controller may advantageously comprise a DC / AC inverter, which may include a class C, class D or class E power amplifier.

[0106] The controller may be configured to supply a varying current with any suitable frequency to the induction heating device. The controller may be configured to supply a varying current with a frequency between about 5 kHz and about 30 MHz to the induction heating device. In some preferred embodiments, the controller is configured to supply a varying current between about 5 kHz and about 500 kHz to the induction heating device. In some embodiments, the controller is configured to supply a high-frequency varying current to the induction heating device. As used herein, the term "high-frequency varying current" refers to a varying current with a frequency between about 500 kHz and about 30 MHz. The high-frequency varying current may have a frequency between about 1 MHz and about 30 MHz (such as between about 1 MHz and about 10 MHz, or such as between about 5 MHz and about 8 MHz).

[0107] The aerosol generating device may include a device housing. The device housing may be elongated. The device housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of those materials, or thermoplastic materials suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. Preferably, the material is lightweight and non-brittle.

[0108] The device housing may define a device cavity for receiving the aerosol-forming substrate. The device cavity is configured to receive at least a portion of the aerosol-generating article. The device cavity may have any suitable shape and size. The device cavity may be substantially cylindrical. The device cavity may have a substantially circular cross-section.

[0109] The induction heating element may be disposed in the device cavity. The induction heating element may be disposed around the device cavity. In the case where the induction heating element is a tubular induction heating element, the induction heating element may define the device cavity. The inner surface of the induction heating element may form the inner surface of the device cavity.

[0110] The first inductor coil and the second inductor coil may be disposed in the device cavity. The first inductor coil and the second inductor coil may be disposed around the device cavity. The first inductor coil and the second inductor coil may define the device cavity. The inner surfaces of the first inductor coil and the second inductor coil may form the inner surface of the device cavity.

[0111] The device may have a proximal end and a distal end opposite the proximal end.Preferably, the device lumen is arranged at the proximal end of the device.

[0112] The device housing may include an air inlet. The air inlet may be configured to allow ambient air to enter the device housing. The device housing may include any number of air inlets. The device housing may include multiple air inlets.

[0113] The device housing may include an air outlet. The air outlet may be configured to allow air to enter the device cavity from within the device housing. The device housing may include any suitable number of air outlets. The device housing may include multiple air outlets.

[0114] The aerosol generating device may define an air flow path extending from the air inlet to the intermediate element of the inductive heating element. This air flow path may enable air to be drawn from the air inlet through the aerosol generating device and through the intermediate element into the device cavity.

[0115] In some embodiments, a portion of the airflow path can be defined between the sensor coil and the device housing. A portion of the airflow path can be defined between the first sensor coil and the device housing. A portion of the airflow path can be defined between the second sensor coil and the device housing. Providing an airflow path between the sensor coil and the device housing can help insulate the device housing from the heated susceptor and the sensor coil, which can also be heated during use. This can help maintain the outer surface of the device housing at a comfortable temperature for the user to touch during use.

[0116] In these embodiments, when a flux concentrator is provided around the inductor coil, a portion of the airflow path defined between the inductor coil and the device housing may be defined between the flux concentrator and the device housing. Similarly, when an induction heating device housing is provided, a portion of the airflow path defined between the inductor coil and the device housing may be defined between the induction heating device housing and the device housing.

[0117] In some embodiments, a portion of the airflow path is defined between the inductor coil and the induction heating element. A portion of the airflow path may be defined between the first inductor coil and the first susceptor. A portion of the airflow path may be defined between the second inductor coil and the second susceptor. Providing an airflow path between the inductor coil and the induction heating element may help insulate the inductor coil from the heated susceptor. Advantageously, this may help reduce any increase in the resistance of the inductor coil during use due to heating from the heated induction heating element.

[0118] In some embodiments, the device cavity may include a proximal end and a distal end opposite the proximal end. In these embodiments, the device cavity may be open at the proximal end for receiving the aerosol generating article. In these embodiments, the device cavity may be substantially closed at the distal end. The device housing may include an air outlet at the distal end of the device cavity. The aerosol generating device may further include an annular seal toward the proximal end of the device cavity. The annular seal may extend into the device cavity. The annular seal may provide a substantially airtight seal between the device housing and the outer surface of the aerosol generating article received in the device cavity. This may reduce the volume of air drawn into the device cavity during use by any gaps existing between the outer surface of the aerosol generating article and the inner surface of the device cavity. This may increase the volume of air drawn into the aerosol generating article through the permeable intermediate element.

[0119] In some embodiments, the device housing includes a mouthpiece. The mouthpiece may include at least one air inlet and at least one air outlet. The mouthpiece may include more than one air inlet. The one or more air inlets may reduce the temperature of the aerosol before it is delivered to the user, and may reduce the concentration of the aerosol before it is delivered to the user.

[0120] In some embodiments, a mouthpiece is provided as part of the aerosol-generating article. As used herein, the term "mouthpiece" refers to a portion of an aerosol-generating system that is placed in the mouth of a user in order to inhale an aerosol generated by the aerosol-generating system directly from an aerosol-generating article received by the aerosol-generating device.

[0121] The aerosol generating device may include a temperature sensor. The temperature sensor may be arranged to sense the temperature of the inductive heating element. The aerosol generating device may include a first temperature sensor arranged to sense the temperature of the first susceptor. The aerosol generating device may include a second temperature sensor arranged to sense the temperature of the second susceptor.

[0122] The aerosol-generating device may comprise a user interface to activate the device, such as a button to initiate heating of the aerosol-generating article.

[0123] An aerosol-generating device may comprise a display to indicate the status of the device or the aerosol-forming substrate.

[0124] The aerosol generating device may comprise a puff sensor for sensing puffing of the aerosol generating system by a user.

[0125] Preferably, the aerosol generating device is portable. The aerosol generating device may be of a size comparable to a conventional cigar or cigarette. The aerosol generating device may have an overall length between about 30 mm and about 150 mm. The aerosol generating device may have an outer diameter between about 5 mm and about 30 mm.

[0126] The aerosol-generating device may form part of an aerosol-generating system.

[0127] The aerosol-generating system may further include an aerosol-generating article. The aerosol-generating article may include a first aerosol-forming substrate; and a second aerosol-forming substrate. When the aerosol-generating article is received in the device cavity, at least a portion of the first aerosol-forming substrate may be received in a first portion of the device cavity, and at least a portion of the second aerosol-forming substrate may be received in a second portion of the device cavity.

[0128] The induction heating element forming part of the induction heating device of the aerosol-generating device is configured to heat the aerosol-forming substrate.

[0129] The aerosol-forming substrate may comprise nicotine. The nicotine-containing aerosol-forming substrate may be a nicotine salt matrix.

[0130] The aerosol-forming substrate may be a liquid. The aerosol-forming substrate may comprise a solid component and a liquid component. Preferably, the aerosol-forming substrate is a solid.

[0131] The aerosol-forming substrate may comprise a plant-based material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a tobacco-containing material comprising volatile tobacco flavoring compounds that are released from the aerosol-forming substrate when heated. The aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may comprise a homogenized plant-based material. The aerosol-forming substrate may comprise a homogenized tobacco material. The homogenized tobacco material may be formed by agglomerating particulate tobacco. In a particularly preferred embodiment, the aerosol-forming substrate comprises a curled sheet of aggregated homogenized tobacco material. As used herein, the term "curled sheet" refers to a sheet having a plurality of roughly parallel ridges or wrinkles.

[0132] The aerosol-forming substrate may include at least one aerosol-forming agent. An aerosol-forming agent is any suitable known compound or mixture of compounds that, in use, facilitates the formation of a dense and stable aerosol and is substantially resistant to thermal degradation at the operating temperature of the system. Suitable aerosol-forming agents are well known in the art and include, but are not limited to, polyols such as triethylene glycol, 1,3-butanediol, and glycerol; esters of polyols such as glycerol mono-, di-, or triacetate; and fatty acid esters of mono-, di-, or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanoic acid. Preferred aerosol-forming agents may include polyols or mixtures thereof, such as triethylene glycol, 1,3-butanediol. Preferably, the aerosol-forming agent is glycerol. If present, the aerosol-forming agent content of the homogenized tobacco material may be equal to or greater than 5 weight percent on a dry weight basis, for example, between about 5 weight percent and about 30 weight percent on a dry weight basis. The aerosol-forming substrate may include other additives and ingredients, such as flavorings.

[0133] The aerosol-forming substrate may be included in an aerosol-generating article. The aerosol-generating device including the induction heating device may be configured to receive at least a portion of the aerosol-generating article. The aerosol-generating article may have any suitable form. The aerosol-generating article may be substantially cylindrical in shape. The aerosol-generating article may be generally elongated. The aerosol-generating article may have a length and a circumference substantially perpendicular to the length.

[0134] The aerosol-forming substrate may be provided as an aerosol-generating segment comprising an aerosol-forming substrate. The aerosol-generating segment may comprise a plurality of aerosol-forming substrates. The aerosol-generating segment may comprise a first aerosol-forming substrate and a second aerosol-forming substrate. In some embodiments, the second aerosol-forming substrate is substantially identical to the first aerosol-forming substrate. In some embodiments, the second aerosol-forming substrate is different from the first aerosol-forming substrate.

[0135] Where the aerosol-generating segment comprises a plurality of aerosol-forming substrates, the number of aerosol-forming substrates may be the same as the number of susceptors in the induction heating element. Similarly, the number of aerosol-forming substrates may be the same as the number of inductor coils in the induction heating device.

[0136] The aerosol-generating segment may be substantially cylindrical in shape. The aerosol-generating segment may be substantially elongated. The aerosol-generating segment may also have a length and a circumference substantially perpendicular to the length.

[0137] Where the aerosol-generating segment comprises a plurality of aerosol-forming substrates, the aerosol-forming substrates may be arranged end-to-end along the axis of the aerosol-generating segment.In some embodiments, the aerosol-generating segment may comprise spaces between adjacent aerosol-forming substrates.

[0138] In some preferred embodiments, the aerosol-generating article can have an overall length of between about 30 mm and about 100 mm. In some embodiments, the aerosol-generating article has an overall length of about 45 mm. The aerosol-generating article can have an outer diameter of between about 5 mm and about 12 mm. In some embodiments, the aerosol-generating article can have an outer diameter of about 7.2 mm.

[0139] The aerosol-generating segment may have a length of between about 7 mm and about 15 mm. In some embodiments, the aerosol-generating segment may have a length of about 10 mm or 12 mm.

[0140] The aerosol-generating segment preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The outer diameter of the aerosol-generating segment may be between about 5 mm and about 12 mm. In one embodiment, the aerosol-generating segment may have an outer diameter of about 7.2 mm.

[0141] The aerosol-generating article may include a filter segment. The filter segment may be located at the downstream end of the aerosol-generating article. The filter segment may be a cellulose acetate filter plug. In some embodiments, the filter segment may have a length of about 5 mm to about 10 mm. In some preferred embodiments, the filter segment may have a length of about 7 mm.

[0142] The aerosol-generating article may comprise an outer wrapping material. The outer wrapping material may be formed of paper. The outer wrapping material may be breathable at the aerosol-generating segment. Specifically, in embodiments comprising a plurality of aerosol-forming substrates, the outer wrapping material may comprise perforations or other air inlets at the interface between adjacent aerosol-forming substrates. Where a gap is provided between adjacent aerosol-forming substrates, the outer wrapping material may comprise perforations or other air inlets at the gap. This may enable an aerosol-forming substrate to be directly provided with air that has not been drawn through another aerosol-forming substrate. This may increase the amount of air received by each aerosol-forming substrate. This may improve the properties of the aerosol generated from the aerosol-forming substrate.

[0143] The aerosol-generating article may further comprise a spacing between the aerosol-forming substrate and the filter segment. The spacing may be about 18 mm, but may be in the range of about 5 mm to about 25 mm.

[0144] It will also be appreciated that specific combinations of the various features described above can be implemented, provided, and used independently. BRIEF DESCRIPTION OF THE DRAWINGS

[0145] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0146] Figure 1 shows a schematic diagram of an induction heating element according to an embodiment of the present disclosure arranged between a pair of inductor coils;

[0147] Figure 2 shows an exploded perspective view of an induction heating element according to an embodiment of the present disclosure;

[0148] Figure 3 Shown Figure 2 A perspective view of an induction heating element;

[0149] Figure 4 shows a cross-sectional view of an aerosol-generating system according to an embodiment of the present disclosure, the aerosol-generating system comprising an aerosol-generating article and an aerosol-generating device having an induction heating device;

[0150] Figure 5 Shown Figure 4 a cross-sectional view of the proximal end of an aerosol generating device, including an airflow path through the device;

[0151] Figure 6 Shown Figure 5 a cross-sectional view of an aerosol-generating device, wherein the aerosol-generating article is received in the device cavity;

[0152] Figure 7 shows a cross-sectional view of the proximal end of an aerosol-generating device according to the present disclosure, with an aerosol-generating article received in a cavity of the device;

[0153] Figure 8 shows an exploded perspective view of an intermediate element of an induction heating element according to an embodiment of the present disclosure; and

[0154] Figure 9 A cross-sectional view of an induction heating device according to an embodiment of the present disclosure is shown, comprising Figure 8 The intermediate element is an induction heating element. DETAILED DESCRIPTION

[0155] Figure 1 A schematic diagram of an induction heating element 10 according to an embodiment of the present disclosure is shown. The induction heating element 10 is an elongated tubular element having a circular cross-section. The induction heating element 10 includes a first susceptor 12; a second susceptor 14; and an intermediate element 16 disposed between the first susceptor 12 and the second susceptor 14. The first susceptor 12 and the second susceptor 14 are each elongated tubular elements having a circular cross-section. The intermediate element 16 is a tubular element having a circular cross-section. The first susceptor 12, the second susceptor 14, and the intermediate element 16 are coaxially aligned end-to-end along a longitudinal axis AA.

[0156] The induction heating element 10 comprises a cylindrical cavity 20 open at both ends, which is defined by the inner surface of the tubular induction heating element 10. The cavity 20 is configured to receive a portion of a cylindrical aerosol-generating article (not shown) comprising an aerosol-forming substrate, such that the outer surface of the aerosol-generating article can be heated by the first and second susceptors, thereby heating the aerosol-forming substrate.

[0157] The cavity 20 comprises three portions: a first portion 22 at a first end defined by the inner surface of the tubular first susceptor 12; a second portion 24 at a second end opposite the first end defined by the inner surface of the tubular second susceptor 14; and a middle portion 26 defined by the inner surface of the tubular intermediate element 16. The first susceptor 12 is arranged to heat a first portion of an aerosol-generating article received in the first portion 22 of the cavity 20, and the second susceptor 14 is arranged to heat a second portion of the aerosol-generating article received in the second portion 24 of the cavity 20.

[0158] The first inductor coil 32 is disposed around the first susceptor 12 and extends substantially the length of the first susceptor 12. Thus, the first susceptor 12 is substantially defined along its length by the first inductor coil 32. When a varying current is supplied to the first inductor coil 32, the first inductor coil 32 generates a varying magnetic field that is concentrated in the first portion 22 of the cavity 20. This varying magnetic field generated by the first inductor coil 32 induces eddy currents in the first susceptor 12, causing the first susceptor 12 to be heated.

[0159] The second inductor coil 34 is disposed around the second susceptor 14 and extends substantially the length of the second susceptor 14. Thus, the second susceptor 14 is substantially defined along its length by the second inductor coil 34. When a varying current is supplied to the second inductor coil 34, the second inductor coil 34 generates a varying magnetic field that is concentrated in the second portion 24 of the cavity 20. This varying magnetic field generated by the second inductor coil 34 induces eddy currents in the second susceptor 14, causing the second susceptor 14 to be heated.

[0160] The intermediate element 16 is not a susceptor because it is formed from an electrically and thermally insulating material. Thus, when exposed to a changing magnetic field generated by the first inductor coil 32 or the second inductor coil 34, the intermediate element 16 does not heat by induction. Furthermore, because the intermediate element is formed from a thermally insulating material, the rate of heat transfer between the first and second susceptors 12, 14 is reduced compared to an induction heating element in which the first and second susceptors are arranged adjacent to each other in direct thermal contact. Consequently, providing the intermediate element 16 between the first and second susceptors 12, 14 enables the first susceptor 12 to selectively heat the first portion 22 of the cavity 20 with minimal heating of the second portion 24 of the cavity 20, and enables the second susceptor 14 to selectively heat the second portion 24 of the cavity 20 with minimal heating of the first portion 22 of the cavity 20.

[0161] Because the intermediate element 16 is also air permeable and enables air to flow into the intermediate portion 26 of the cavity 20, the airflow through the intermediate element 16 also cools the intermediate portion 26 of the cavity 20 and the ends of the first susceptor 12 and the second susceptor 14 adjacent the intermediate element 16. Thus, during heating of the first susceptor 12 to generate an aerosol from an aerosol-forming substrate received in the first portion 22 of the cavity 20, the airflow through the intermediate element 16 further insulates the second susceptor 14 and the second portion 24 of the cavity 20 from being heated by the first susceptor 12. Similarly, during heating of the second susceptor 14 to generate an aerosol from an aerosol-forming substrate received in the second portion 24 of the cavity 20, the airflow through the intermediate element 16 further insulates the first susceptor 12 and the first portion 22 of the cavity 20 from being heated by the second susceptor 14.

[0162] By simultaneously supplying varying currents to first inductor coil 32 and second inductor coil 34, first susceptor 12 and second susceptor 14 may be heated simultaneously. Alternatively, first susceptor 12 and second susceptor 14 may be heated independently or alternately by supplying varying current to first inductor coil 32 without supplying current to second inductor coil 34, and then supplying varying current to second inductor coil 34 without supplying current to first inductor coil 32. It is also contemplated that different currents may be supplied sequentially to first inductor coil 32 and second inductor coil 34.

[0163] Figures 2 to 6 A schematic diagram of an aerosol generating system according to an embodiment of the present disclosure is shown. The aerosol generating system comprises an aerosol generating device 100 and an aerosol generating article 200. The aerosol generating device 100 comprises an induction heating device 110 according to the present disclosure. The induction heating device 110 comprises an induction heating element 120 according to the present disclosure.

[0164] Figure 2 and Figure 3 FIG2 shows a schematic diagram of an induction heating element 120. The induction heating element 120 includes a first susceptor 122, a second susceptor 124, a third susceptor 126, a first intermediate element 128, a second intermediate element 130, and an end element 132. The first intermediate element 128 is disposed between the first susceptor 122 and the second susceptor 124. The second intermediate element 130 is disposed between the second susceptor 124 and the third susceptor 126. The end element 132 is disposed at the distal end of the induction heating element 120, which is the end of the first susceptor 122 opposite the end adjacent to the first intermediate element 128.

[0165] In this embodiment, each of the first susceptor 122, the second susceptor 124, and the third susceptor 126 are identical. Each susceptor 122, 124, 126 is an elongated tubular susceptor defining an internal lumen. Each susceptor and its corresponding internal lumen are substantially cylindrical, having a circular cross-section that is constant along the length of the susceptor. The internal lumen of the first susceptor 122 defines a first region 134. The internal lumen of the second susceptor 124 defines a second region 136. The internal lumen of the third susceptor defines a third region 138.

[0166] Similarly, the first intermediate element 128 and the second intermediate element 130 are identical. The intermediate elements 128, 130 are tubular and define an internal lumen. Each intermediate element 128, 130 is substantially cylindrical, having a circular cross-section that is constant along the length of the intermediate element. The outer diameter of the intermediate elements 128, 130 is the same as the outer diameter of the susceptors 122, 124, 126, so that the outer surface of the intermediate elements 128, 130 can be flushly aligned with the outer surface of the susceptors 122, 124, 126. The inner diameter of the intermediate elements 128, 130 is also the same as the inner diameter of the susceptors 122, 124, 126, so that the inner surface of the intermediate elements 128, 130 can be flushly aligned with the inner surface of the susceptors 122, 124, 126.

[0167] The first susceptor 122, the first intermediate element 128, the second susceptor 124, the second intermediate element 130, and the third susceptor 126 are arranged end-to-end and coaxially aligned on the axis BB. In this arrangement, the susceptors 122, 124, 126 and the intermediate elements 128, 130 form a tubular elongated cylindrical structure. In some embodiments, this structure can form an induction heating element according to the present disclosure.

[0168] The end element 132 is also identical to the intermediate elements 128 , 130 . The end element 132 is disposed at the distal end of the first susceptor 122 and extends the tubular elongated cylindrical structure formed by the susceptors 122 , 124 , 126 and the intermediate elements 128 , 130 to form the induction heating element 120 .

[0169] The elongated tubular induction heating element 120 includes an interior lumen 140. The interior lumen 140 of the induction heating element 120 is defined by the interior lumens of the susceptors 122, 124, 126 and the interior lumens of the intermediate elements 128, 130, and the end element 132. As described in more detail below, the interior lumen 140 of the induction heating element 120 is configured to receive the aerosol-generating segment of the aerosol-generating article 200.

[0170] Intermediate elements 128, 130 and end element 132 are formed from an electrically and thermally insulating material, which in this embodiment is a ceramic material such as zirconium dioxide (ZrO2). Thus, susceptors 122, 124, 126 are substantially electrically and thermally insulated from one another. The material of intermediate elements 128, 130 and end elements is also substantially impermeable to air. However, intermediate elements 128, 130, and end element 132 are permeable to air. Each of intermediate elements 128, 130, and end element 132 includes a plurality of air passageways in the form of elongated slots 142. The slots 142 extend from the outer surface to the inner surface and allow air to flow from the outer surface into the inner cavity.

[0171] Figure 4 、 Figure 5 and Figure 6 Schematic cross-sections of an aerosol-generating device 100 and an aerosol-generating article 200 are shown.

[0172] The aerosol-generating device 100 includes a generally cylindrical device housing 102 having a shape and size similar to that of a conventional cigar. The device housing 102 defines a device cavity 104 at a proximal end. The device cavity 104 is substantially cylindrical, open at the proximal end, and substantially closed at a distal end opposite the proximal end. The device cavity 104 is configured to receive the aerosol-generating segment 210 of the aerosol-generating article 200. Thus, the length and diameter of the device cavity 104 are substantially similar to the length and diameter of the aerosol-generating segment 210 of the aerosol-generating article 200.

[0173] The aerosol generating device 100 further comprises a power source 106 in the form of a rechargeable nickel-cadmium battery, a controller 108 in the form of a printed circuit board comprising a microprocessor, an electrical connector 109 and an induction heating device 110. The power source 106, the controller 108 and the induction heating device 110 are all housed within the device housing 102. The induction heating device 110 of the aerosol generating device 100 is arranged at the proximal end of the device 100 and is generally arranged around the device cavity 104. The electrical connector 109 is arranged at the distal end of the device housing 102, opposite the device cavity 104.

[0174] The controller 108 is configured to control the supply of power from the power source 106 to the induction heating device 110. The controller 108 further includes a DC / AC inverter, which includes a class D power amplifier and is configured to supply a varying current to the induction heating device 110. The controller 108 is also configured to control the recharging of the power source 106 from the electrical connector 109. Additionally, the controller 108 includes a puff sensor (not shown) configured to sense when a user takes a puff on an aerosol-generating article received in the device cavity 104.

[0175] The induction heating device 110 includes three induction heating units, including a first induction heating unit 112, a second induction heating unit 114, and a third induction heating unit 116. The first induction heating unit 112, the second induction heating unit 114, and the third induction heating unit 116 are substantially identical.

[0176] The first induction heating unit 112 includes a cylindrical tubular first inductor coil 150 , a cylindrical tubular first flux concentrator 152 disposed around the first inductor coil 150 , and a cylindrical tubular first inductor unit housing 154 disposed around the first flux concentrator 152 .

[0177] The second induction heating unit 114 includes a cylindrical tubular second inductor coil 160 , a cylindrical tubular second flux concentrator 162 disposed around the second inductor coil 160 , and a cylindrical tubular second inductor unit housing 164 disposed around the second flux concentrator 162 .

[0178] The third induction heating unit 116 includes a cylindrical tubular third inductor coil 170 , a cylindrical tubular third flux concentrator 172 disposed around the third inductor coil 170 , and a cylindrical tubular third inductor unit housing 174 disposed around the third flux concentrator 172 .

[0179] Thus, each induction heating unit 112, 114, 116 forms a substantially tubular unit having a circular cross-section. In each induction heating unit 112, 114, 116, a flux concentrator extends over the proximal and distal ends of the inductor coil, such that the inductor coil is disposed within the annular cavity of the flux concentrator. Similarly, each induction heating unit housing extends over the proximal and distal ends of the flux concentrator, such that the flux concentrator and the inductor coil are disposed within the annular cavity of the induction heating unit housing. This arrangement enables the flux concentrator to concentrate the magnetic field generated by the inductor coil within the inner cavity of the inductor coil. This arrangement also enables the inductor unit housing to retain the flux concentrator and the inductor coil within the inductor unit housing.

[0180] The induction heating device 110 further includes an induction heating element 120. The induction heating element 120 is disposed around the inner surface of the device cavity 104. In this embodiment, the device housing 102 defines the inner surface of the device cavity 104. However, it is contemplated that in some embodiments, the inner surface of the device cavity is defined by the inner surface of the induction heating element 120.

[0181] The induction heating units 112, 114, 116 are disposed around the induction heating element 120 such that the induction heating element 120 and the induction heating units 112, 114, 116 are concentrically arranged around the device cavity 104. The first induction heating unit 112 is disposed at the distal end of the device cavity 104 around a first susceptor 122. The second induction heating unit 114 is disposed at the central portion of the device cavity 104 around a second susceptor 124. The third induction heating unit 116 is disposed at the proximal end of the device cavity 104 around a third susceptor 126. It is contemplated that in some embodiments, the flux concentrator may also extend into the intermediate elements of the induction heating elements to further distort the magnetic field generated by the inductor coil toward the inductor.

[0182] The first inductor coil 150 is connected to the controller 108 and the power supply 106, and the controller 108 is configured to supply a varying current to the first inductor coil 150. When the varying current is supplied to the first inductor coil 150, the first inductor coil 150 generates a varying magnetic field that heats the first susceptor 122 by induction.

[0183] The second inductor coil 160 is connected to the controller 108 and the power supply 106, and the controller 108 is configured to supply a varying current to the second inductor coil 160. When the varying current is supplied to the second inductor coil 160, the second inductor coil 160 generates a varying magnetic field that heats the second susceptor 124 by induction.

[0184] The third inductor coil 170 is connected to the controller 108 and the power supply 106, and the controller 108 is configured to supply a varying current to the third inductor coil 170. When the varying current is supplied to the third inductor coil 170, the third inductor coil 170 generates a varying magnetic field that heats the third susceptor 126 by induction.

[0185] The device housing 102 also defines an air inlet 180 proximate the distal end of the device cavity 104. The air inlet 180 is configured to allow ambient air to be drawn into the device housing 102. Airflow paths are defined through the device to allow air to be drawn from the air inlet 180 into the device cavity 104. A first airflow path 181 is defined between the air inlet 180 and an air outlet in the distal end of the device cavity 104. A second airflow path 182 is defined between the air inlet 180 and the slot 142 of the end member 132 of the induction heating element 120. A third airflow path 184 is defined between the air inlet 180 and the slot 142 of the first intermediate member 128 of the induction heating element 120, extending between the first induction heating unit housing 154 and the device housing 102. A fourth airflow path 186 is defined between the air inlet 180 and the slot 142 of the second intermediate member 130, extending between the second induction heating unit housing 174 and the device housing 102.

[0186] The aerosol-generating article 200 is generally in the form of a cylindrical rod having a diameter similar to the inner diameter of the device cavity 104. The aerosol-generating article 200 comprises a cylindrical cellulose acetate filter segment 204 and a cylindrical aerosol-generating section 210 wrapped together by an outer wrapper 220 of cigarette paper.

[0187] The filter segment 204 is arranged at the proximal end of the aerosol-generating article 200 and forms the mouthpiece of the aerosol-generating system, upon which a user draws to receive the aerosol generated by the system.

[0188] The aerosol-generating segment 210 is disposed at the distal end of the aerosol-generating article 200 and has a length substantially equal to the length of the device cavity 104. The aerosol-generating segment 210 comprises a plurality of aerosol-forming substrates, including: a first aerosol-forming substrate 212 at the distal end of the aerosol-generating article 200, a second aerosol-forming substrate 214 adjacent to the first aerosol-forming substrate 212, and a third aerosol-forming substrate 216 adjacent to the second aerosol-forming substrate 214 at the proximal end of the aerosol-generating segment 210. It will be appreciated that in some embodiments, two or more aerosol-forming substrates may be formed from the same material. However, in this embodiment, each of the aerosol-forming substrates 212, 214, 216 is different. The first aerosol-forming substrate 212 comprises a gathered, curled sheet of homogenized tobacco material without an added flavoring agent. The second aerosol-forming substrate 214 comprises a gathered, curled sheet of homogenized tobacco material including a flavoring agent in the form of menthol. The third aerosol-forming substrate may include a flavoring agent in the form of menthol and does not include tobacco material or any other nicotine source. Each of the aerosol-forming substrates 212, 214, 216 may also include additional components, such as one or more aerosol-forming agents and water, so that heating the aerosol-forming substrate generates an aerosol having desired sensory properties.

[0189] The proximal end of the first aerosol-forming substrate 212 is exposed in that it is not covered by the outer wrap material 220. The outer wrap material 220 comprises a row of first perforations 222 surrounding the aerosol-generating article 200 at the interface between the first aerosol-forming substrate 212 and the second aerosol-forming substrate 214. The outer wrap material 220 also comprises a row of second perforations 224 surrounding the aerosol-generating article 200 at the interface between the second aerosol-forming substrate 214 and the third aerosol-forming substrate 216. The perforations 222, 224 enable air to be drawn into the aerosol-generating segment 210.

[0190] In this embodiment, the first aerosol-forming substrate 212, the second aerosol-forming substrate 214, and the third aerosol-forming substrate 216 are arranged end to end. However, it is envisaged that in other embodiments, a spacing may be provided between the first aerosol-forming substrate and the second aerosol-forming substrate, and a spacing may be provided between the second aerosol-forming substrate and the third aerosol-forming substrate.

[0191] like Figure 6As shown, the length of the first aerosol-forming substrate 212 is such that the first aerosol-forming substrate 212 extends from the distal end of the device cavity 104, through the first region 134 of the first susceptor 122, and to the slot 142 of the first intermediate element 128. The length of the second aerosol-forming substrate 214 is such that the second aerosol-forming substrate 214 extends from the slot 142 of the first intermediate element 128, through the second region 136 of the second susceptor 124, and to the slot 142 of the second intermediate element 130. The length of the third aerosol-forming substrate 216 is such that the third aerosol-forming substrate 216 extends from the slot 142 of the second intermediate element 130 to the proximal end of the device cavity 104.

[0192] In use, when the aerosol-generating article 200 is received in the device cavity 104, a user can draw on the proximal end of the aerosol-generating article 200 to inhale the aerosol generated by the aerosol-generating system. When the user draws on the proximal end of the aerosol-generating article 200, air is drawn into the device housing 102 at the air inlet 180 and into the aerosol-generating segment 210 of the aerosol-generating article 200 along air flow paths 181, 182, 184, 186. Air is drawn into the proximal end of the first aerosol-forming substrate 212 through the slots 142 in the end element 132 and the outlet in the distal end of the device cavity 104. Air is drawn into the proximal end of the second aerosol-forming substrate 214 through the slots 142 in the first intermediate element 128 and the first perforations 222 in the outer wrapping material 220 of the article 200. Air is drawn into the proximal end of the third aerosol-forming substrate 216 through the slots 142 in the second intermediate element 130 and the second perforations 224 in the outer wrapper 220 of the article 200. In this way, each of the aerosol-forming substrates 212, 214, 216 directly receives ambient air.

[0193] In this embodiment, the controller 108 of the aerosol-generating device 100 is configured to supply power to the induction coils of the induction heating device 110 in a predetermined sequence. The predetermined sequence includes supplying a varying current to the first induction coil 150 during the first puff from the user; then, after the first puff has been completed, supplying a varying current to the second induction coil 160 during the second puff from the user; and then, after the second puff has been completed, supplying a varying current to the third induction coil 170 during the third puff from the user. At the fourth puff, the sequence begins again at the first induction coil 150. This sequence results in heating the first aerosol-forming substrate 212 during the first puff, heating the second aerosol-forming substrate 214 during the second puff, and heating the third aerosol-forming substrate 216 during the third puff. Because the aerosol-forming substrates 212, 214, 216 of the article 200 are all different, this sequence results in a different experience for the user with each puff on the aerosol-generating system.

[0194] It will be appreciated that the controller 108 may be configured to supply power to the inductor coils in a different sequence or simultaneously, depending on the desired aerosol delivery to the user. In some embodiments, the aerosol generating device may be controlled by a user to change this sequence.

[0195] Figure 7 shows a substantially similar Figures 2 to 6 A schematic cross-section of an aerosol generating system of an aerosol generating system is shown in FIG, wherein like reference numerals are used to refer to like features. Figure 7 In an embodiment of the present invention, the air flow path is provided in the aerosol generating device 100 between the induction coil and the susceptor, rather than between the induction heating unit and the device housing. Figure 7 The arrows shown in show the airflow path through the system.

[0196] Figure 8 and Figure 9 A schematic representation of an intermediate element 300 according to another embodiment of the present disclosure is shown. In this embodiment, the intermediate element between adjacent susceptors of the inductive heating element and any provided end elements comprises a porous material. The porous material is breathable, and therefore, the intermediate element 300 does not need to provide air passages, such as the slots 142 of the intermediate elements 128, 130 described above.

[0197] Specifically, the intermediate element 300 includes three porous materials, a first porous material 302, a second porous material 304, and a third porous material 306. The porosity of each of the first porous material 302, the second porous material 304, and the third porous material 306 is different, resulting in a different gas permeability of each material. Figure 9As shown, the differences in porosity and gas permeability of the porous materials enable the intermediate element 300 to be configured to promote gas flow in a particular direction.

[0198] The first porous material 302, the second porous material 304, and the third porous material 306 are each formed from a tubular body of porous material defining an inner cavity. Figure 8 As shown, the outer diameter and inner diameter of the porous materials 302, 304, 306 are substantially the same, so that the porous materials 302, 304, 306 can be stacked to form a tubular intermediate element with a substantially constant outer diameter and inner diameter. The first porous material 302 and the third porous material 306 have substantially the same thickness and are relatively thin compared to the thickness of the second porous material 304.

[0199] Specifically, in this embodiment, the second porous material 304 is disposed above the first porous material 302, and the third porous material 306 is disposed above the second porous material 304. The second porous material 304 has a higher porosity than the first porous material 302, and the third porous material 306 has a higher porosity than the second porous material 304.

[0200] exist Figure 9 In the figure, the intermediate element 300 is shown as being arranged at Figures 2 to 6 The intermediate element 300 is positioned between the first susceptor 122 and the second susceptor 124 of the embodiment of the present invention. The intermediate element 300 is arranged such that the first porous material 302 is adjacent to the first susceptor 122 and the third porous material 306 is adjacent to the second susceptor 124. Thus, the porosity of the intermediate element 300 increases in the proximal direction from the first susceptor 122 to the second susceptor 124. Advantageously, this can promote airflow in the proximal direction toward the lumen of the second susceptor 124, as shown in FIG. Figure 9 As shown, the airflow is directed toward the inner cavity of the first susceptor 122 rather than the inner cavity of the first susceptor 122 .

[0201] It will be appreciated that the embodiments described above are merely specific examples and that other embodiments are contemplated in light of the present disclosure.

Claims

1. An induction heating element for an aerosol generating system, the induction heating element comprising: a cavity for receiving an aerosol-forming substrate to be heated by the induction heating element; First receptor; Second receptor; as well as an intermediate element, the intermediate element being disposed between the first susceptor and the second susceptor, the intermediate element being breathable, wherein the intermediate element comprises at least one of the following: a thermal insulation material for thermally insulating the first susceptor from the second susceptor; as well as An electrically insulating material is provided for electrically insulating the first susceptor from the second susceptor.

2. The induction heating element according to claim 1, wherein: The first susceptor is a tubular susceptor defining a portion of the induction heating element cavity; The second susceptor is a tubular susceptor defining a portion of the induction heating element cavity; and The intermediate element is a tubular intermediate element defining a portion of the induction heating element cavity.

3. An induction heating element according to claim 1 or 2, wherein the induction heating element comprises an outer side and an inner side opposite the outer side, the inner side at least partially defining the cavity for receiving the aerosol-forming substrate, and wherein the intermediate element comprises one or more air passages configured to permit air to flow from the outer side to the inner side. The induction heating element of claim 1 , wherein the intermediate element comprises a porous material.

5. The induction heating element of claim 4, wherein the intermediate element comprises a first porous material and a second porous material, the second porous material having a higher porosity than the first porous material.

6. The induction heating element of claim 5, wherein the intermediate element includes a distal end adjacent to the first susceptor and a proximal end opposite the distal end and adjacent to the second susceptor, and wherein the first porous material is disposed toward the distal end of the intermediate element and the second porous material is disposed toward the proximal end of the intermediate element.

7. The induction heating element according to claim 5 or 6, wherein the intermediate element comprises a third porous material arranged between the first porous material and the second porous material, the third porous material having a higher porosity than the first porous material, and the third porous material having a lower porosity than the second porous material.

8. An induction heating device, comprising: The induction heating element according to any one of claims 1 to 7; a first inductor coil; as well as Second inductor coil, wherein: the first inductor coil is arranged relative to the induction heating element such that a varying current supplied to the first inductor coil generates a varying magnetic field that heats the first susceptor of the induction heating element; and The second inductor coil is arranged relative to the induction heating element such that a varying current supplied to the second inductor coil generates a varying magnetic field that heats the second susceptor of the induction heating element.

9. The induction heating device according to claim 8, wherein: The first inductor coil is a tubular coil having an inner cavity, the first susceptor being arranged within the inner cavity of the first susceptor coil; and The second inductor coil is a tubular coil having an inner cavity, and the second susceptor is arranged in the inner cavity of the second inductor coil.

10. An aerosol generating device, comprising the induction heating device according to claim 8 or 9.

11. An aerosol generating device, comprising: A device housing defining a device cavity for receiving an aerosol-forming substrate ； An induction heating device, comprising: An induction heating element, comprising: a cavity for receiving an aerosol-forming substrate to be heated by the induction heating element; a first susceptor disposed around a first portion of the device cavity; a second susceptor disposed around a second portion of the device lumen; and an intermediate element disposed around a middle portion of the device lumen between the first portion and the second portion of the device lumen, the intermediate element being gas permeable, wherein the intermediate element comprises at least one of: a thermal insulation material for thermally insulating the first susceptor from the second susceptor; and an electrically insulating material for electrically insulating the first susceptor from the second susceptor; a first inductor coil disposed around at least a portion of the first susceptor and the first portion of the device lumen; and a second inductor coil disposed around at least a portion of the second susceptor and the second portion of the device lumen; and a power supply electrically connected to the induction heating device and configured to provide a varying current to the first inductor coil and the second inductor coil, in: When the varying current is supplied to the first inductor coil, the first inductor coil generates a varying magnetic field that heats the first susceptor; and When the varying current is supplied to the second inductor coil, the second inductor coil generates a varying magnetic field that heats the second susceptor.

12. An aerosol generating device according to claim 11, wherein the device housing further comprises an air inlet, and the aerosol generating device defines an air flow path extending from the air inlet to the intermediate element of the induction heating element, so that air can be drawn from the air inlet through the aerosol generating device and into the device cavity through the intermediate element.

13. An aerosol generating device according to claim 12, wherein a portion of the airflow path is defined between the first inductor coil and the device housing, and a portion of the airflow path is defined between the second inductor coil and the device housing.

14. An aerosol generating device according to claim 12 or 13, wherein a portion of the airflow path is defined between the first inductor coil and the first susceptor, and a portion of the airflow path is defined between the second inductor coil and the second susceptor.

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