Aerosol generating system with multiple susceptors

Abstract

To provide an aerosol generating device which improves heat distribution when heating an aerosol generating article.SOLUTION: Provided is an aerosol generating system having an aerosol generating device 100 including: a housing 110 having a chamber 120 sized to receive at least a portion of an aerosol generating article 10; and an induction element 130 disposed around at least a portion of the chamber. The aerosol generating device includes a plurality of elongated susceptor elements 180 protruding into the chamber, and the plurality of elongated susceptor elements extend along the long axis of the chamber and are spaced from each other. The aerosol generating device also includes a power supply 140 and a controller 150 connected to an inductor coil 130. The controller controls the induction element 130 so as to sequentially provide a second alternating magnetic field for a second period of time after providing a first alternating magnetic field for a first period of time, and provides an alternating current to the inductor coil.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an aerosol generating device. In particular, the present invention relates to an aerosol generating device having an induction heater for heating an aerosol-generating article using a susceptor. The present invention also relates to an aerosol generating system including such an aerosol generating device in combination with an aerosol-generating article for use in the aerosol generating device. [Background technology]

[0002] Several electrically operated aerosol generating systems have been proposed in the art, in which an aerosol generating device having an electric heater is used to heat an aerosol-forming substrate, such as a tobacco plug. One purpose of such aerosol generating systems is to reduce known harmful smoke components of the type produced by the combustion and pyrolysis of tobacco in conventional cigarettes. Typically, the aerosol-generating substrate is provided as part of an aerosol-generating article that is inserted into a chamber or cavity of the aerosol generating device. In some known systems, a resistive heating element, such as a heating blade, is inserted into or around the aerosol-generating substrate when the aerosol-generating article is received by the aerosol generating device in order to heat the aerosol-generating substrate to a temperature capable of releasing volatile components capable of forming an aerosol. In other aerosol generating systems, an induction heater is used rather than a resistive heating element. An induction heater typically comprises an inductor forming part of the aerosol generating device and a conductive susceptor element that is positioned in thermal proximity to the aerosol-forming substrate. During use, the inductor generates an alternating magnetic field which creates eddy currents and hysteresis losses in the susceptor element, causing heating of the susceptor element and thereby heating the aerosol-forming substrate.

[0003] In known systems having an inductor and a conductive susceptor element, the susceptor element is typically secured within the chamber of the aerosol-generating device and configured to extend at least partially into an aerosol-generating article received within the cavity. When energized by the inductor coil, the susceptor element heats an aerosol-forming substrate of the aerosol-generating article from within. For example, the susceptor element may be positioned to penetrate the aerosol-forming substrate of the aerosol-generating article when the aerosol-generating article is received within the chamber.

[0004] It would be desirable to provide an aerosol generating device that provides improved heat distribution when heating an aerosol-generating article. Summary of the Invention

[0005] According to a first aspect of the present invention, there is provided an aerosol generation system comprising an aerosol generator having a housing, a heating chamber defining a heating zone and sized to receive at least a portion of an aerosol-forming substrate within the heating zone, an inductive element disposed around or adjacent to the heating zone, a power source, and a controller connected to the inductive element and configured to provide an alternating current to the inductive element to generate an alternating magnetic field within the heating zone, The inductive element may be controlled to sequentially provide a first alternating magnetic field having a first frequency for a first period followed by a second alternating magnetic field having a second frequency for a second period.

[0006] Advantageously, in use, the first alternating magnetic field may cause preferential heating of a first susceptor located within the heating zone, and the second alternating magnetic field may cause preferential heating of a second susceptor located within the heating zone. This may result in the first susceptor being heated to a higher temperature than the second susceptor during the first time period, and the second susceptor being heated to a higher temperature than the first susceptor during the second time period. Thus, both the first and second susceptors may be heated simultaneously, but the first alternating magnetic field is more efficiently coupled to the first susceptor than the first alternating current is coupled to the second susceptor during the first time period, resulting in a higher temperature of the first susceptor than the second susceptor during the first time period. Alternatively, the second alternating magnetic field may cause preferential heating of a first susceptor located within the heating zone, and the first alternating magnetic field may cause preferential heating of a second susceptor located within the heating zone. This can result in the second susceptor being heated to a higher temperature than the first susceptor during a first period of time, and the first susceptor being heated to a higher temperature than the second susceptor during a second period of time.

[0007] An alternating magnetic field having any particular frequency may produce different induction behavior in different types of susceptors. For example, if the first and second susceptors have different physical dimensions, they may behave differently when placed in the alternating magnetic field, and one or the other of the susceptors may be heated to a higher temperature than the other of the susceptors. Similarly, if the shapes of the first and second susceptors are different, the induction behavior may be different. Similarly, if the materials of the first and second susceptors are different, for example, if the resistivity or permeability of the first and second susceptors are different, the induction behavior may be different.

[0008] The first susceptor may have a first shape, a first cross-section, a first length dimension, a first width dimension, and a first thickness dimension, and the second susceptor may have a second shape, a second cross-section, a second length dimension, a second width dimension, and a second thickness dimension, where at least one of the first and second shapes, the first and second cross-sections, the first and second length dimensions, the first and second width dimensions, and the first and second thickness dimensions are different. More than one of the first and second shapes, the first and second cross-sections, the first and second length dimensions, the first and second width dimensions, and the first and second thickness dimensions may be different.

[0009] The first susceptor may have a shape selected from the list consisting of rod-shaped, pin-shaped, tubular, blade-shaped, sheet, or a specific shape, and the second susceptor may have a shape selected from the list consisting of rod-shaped, pin-shaped, tubular, blade-shaped, sheet, or a specific shape, where the shape of the second susceptor is different from the shape of the first susceptor.

[0010] The first susceptor may have a cross-section selected from the list consisting of a circle, an ellipse, a square, a rectangle, and a triangle, and the second susceptor may have a cross-section selected from the list consisting of a circle, an ellipse, a square, a rectangle, and a triangle, the cross-section of the second susceptor being different in shape from the first susceptor.

[0011] The first susceptor may be formed from a first material and the second susceptor may be formed from a second material, where the first material has one or more material properties different from the second material. The one or more properties may include the resistivity of the material and the magnetic permeability of the material.

[0012] The first susceptor may have a material selected from the list consisting of iron alloy, stainless steel, aluminum, nickel, nickel alloy, graphite, or carbon, and the second susceptor may have a material selected from the list consisting of iron alloy, stainless steel, aluminum, nickel, nickel alloy, graphite, or carbon, the material of the second susceptor being different from the shape of the first susceptor. The first and second susceptors may be formed from different compositions of the same alloy, for example different compositions of stainless steel, where the different compositions result in different material properties, particularly resistivity or magnetic permeability.

[0013] By selecting different parameters, the first and second susceptors can be optimized for heating with alternating magnetic fields of different frequencies, which can allow an aerosol generation system to operate with two different susceptors, each optimized for heating with alternating magnetic fields of different frequencies.

[0014] When the aerosol generating device is operated, if the temperature of the first susceptor is high enough to aerosolize material from the aerosol-forming substrate, but the temperature of the second susceptor is not high enough to aerosolize material from the aerosol-forming substrate, a portion of the aerosol-forming substrate located near the first susceptor may be preferentially aerosolized for a first period of time. Thus, sequential heating of different portions of the aerosol-forming substrate may be achieved by operating the device to generate a first alternating magnetic field having a first frequency to first heat the first susceptor preferentially relative to the second susceptor, and then generate a second alternating magnetic field having a second frequency to heat the second susceptor preferentially relative to the second susceptor. Sequential heating may advantageously allow for optimized delivery of aerosol to a user over the duration of a smoking experience.

[0015] One of the first or second susceptor may be associated with a first aerosol-forming substrate and intended to heat the first aerosol-forming substrate, and the other of the first or second susceptor may be associated with a second aerosol-forming substrate and intended to heat the second aerosol-forming substrate.

[0016] Furthermore, the frequency of the alternating magnetic field may be adjusted between the first and second frequencies to optimize heating of the aerosol-forming substrate during consumption.

[0017] A method of consuming an aerosol-generating article comprising an aerosol-forming substrate using the above-mentioned aerosol-generating system may comprise the steps of: inserting the aerosol-generating article into a heating chamber of an aerosol-generating device such that at least a portion of the aerosol-forming substrate is located within the heating zone; activating the inductive element to provide a first alternating magnetic field having a first frequency for a first period of time, thereby preferentially heating a first susceptor located within the heating zone for the first period of time; and activating the inductive element to provide a second alternating magnetic field having a second frequency for a second period of time, thereby preferentially heating a second susceptor located within the heating zone for the second period of time. The first portion of the aerosol-forming substrate is heated by the first susceptor for the first period of time, and the second portion of the aerosol-forming substrate is heated by the second susceptor for the second period of time.

[0018] In some embodiments, the inductive element can be controlled to provide three or more different alternating magnetic fields for three or more separate periods, each of the three or more alternating magnetic fields having a different frequency. Thus, three or more susceptors can be preferentially heated by each of the three or more different alternating magnetic fields. In this way, sequential heating in three or more zones within the aerosol-forming substrate can be achieved. Furthermore, adjustment of the frequency can enable optimized heating of three or four zones of the aerosol-forming substrate.

[0019] In some embodiments of the aerosol generating system, the aerosol generating device may include a first susceptor and a second susceptor. That is, the first and second susceptors may be components of the aerosol generating device. Such susceptors may, for example, extend into or be associated with a heating chamber of the aerosol generating device. The aerosol generating device may include a plurality of elongated susceptor elements that protrude into the heating chamber, the plurality of elongated susceptor elements extending in a longitudinal direction of the heating chamber and spaced apart from one another, the plurality of elongated susceptor elements including at least a first susceptor and a second susceptor.

[0020] The plurality of elongated susceptor elements may be substantially parallel to one another. Each of the first and second susceptor elements, or the plurality of elongated susceptor elements, may be removably attached to the aerosol generating device. The aerosol generating system may comprise the first and second susceptor elements, or the plurality of elongated susceptor elements, and a base portion configured for removably attaching to a housing of the aerosol generating device. The first and second susceptor elements, or the plurality of elongated susceptor elements, may be attached to the base portion such that when the base portion is removably coupled to the housing, the first and second susceptor elements, or the plurality of elongated susceptor elements protrude into the heating chamber.

[0021] Preferably, the aerosol-generating system comprises an aerosol-generating device and an aerosol-generating article, the aerosol-generating article including an aerosol-forming substrate and dimensioned to be received by the heating chamber such that at least a portion of the aerosol-forming substrate is within the heating zone. The aerosol-generating article may include a first susceptor and a second susceptor, i.e. the first susceptor and the second susceptor may be components of the aerosol-generating article arranged to heat the aerosol-forming substrate.

[0022] Regardless of whether the susceptor is located within an aerosol-generating device or an aerosol-generating article, the first susceptor may have a first shape and the second susceptor may have a second shape that is different from the first shape. The first susceptor may have a first cross-section and the second susceptor may have a second cross-section that is different from the first cross-section. For example, the first susceptor may be in the shape of an elongated blade having a rectangular cross-section and the second susceptor may be in the shape of an elongated tube having a circular cross-section. The first susceptor may have different dimensions relative to the second susceptor.

[0023] The first susceptor may be formed of a first material and the second susceptor may be formed of a second material different from the first material. For example, the first material may be a magnetic material and the second material may be a non-magnetic material. The first material may have a first resistivity and the second material may have a second resistivity different from the first resistivity. The first susceptor may be an iron-based material such as stainless steel and the second susceptor may be a carbon material or an aluminum material.

[0024] The inductive element may be a single coil configured to provide both the first and second alternating magnetic fields, and the controller may control a parameter to determine whether the single coil generates the first or second alternating magnetic field.

[0025] The inductive element may include at least a first coil and a second coil. The first coil may be operable to provide a first alternating magnetic field and the second coil may be operable to provide a second alternating magnetic field. The controller may control whether the first coil or the second coil is operated to generate either the first alternating magnetic field or the second alternating magnetic field.

[0026] In an alternative aspect, an aerosol generating device may include a housing having a chamber sized to receive at least a portion of an aerosol-generating article, a plurality of elongated susceptor elements projecting into the chamber, an inductor coil disposed about at least a portion of the chamber, and a power supply and controller connected to the inductor coil and configured to provide an alternating current to the inductor coil such that, in use, the inductor coil generates an alternating magnetic field to heat the plurality of elongated susceptor elements, thereby heating at least a portion of the aerosol-generating article received in the chamber. The plurality of elongated susceptor elements extend along a longitudinal axis of the chamber and are spaced apart from one another.

[0027] This alternative embodiment of the aerosol generating device may be used in any of the aerosol generating systems described above. The following preferred features may relate to both the aerosol generating system and the alternative embodiment of the aerosol generating device described above.

[0028] As used herein, the term "longitudinal" is used to describe a direction along a major axis of an aerosol-generating device, an aerosol-generating article, or a component of an aerosol-generating device or an aerosol-generating article, and the term "transverse" is used to describe a direction perpendicular to the longitudinal axis. The heating chamber is sometimes simply referred to as the "chamber." When referring to the chamber, the term "longitudinal" refers to the direction in which the aerosol-generating article is inserted into the chamber, and the term "transverse" refers to the direction perpendicular to the direction in which the aerosol-generating article is inserted into the chamber.

[0029] Typically, the chamber has an open end through which the aerosol-generating article is inserted and a closed end opposite the open end. In such embodiments, the longitudinal direction is the direction extending between the open end and the closed end. In certain embodiments, the longitudinal axis of the chamber is parallel to the longitudinal axis of the aerosol-generating device. For example, the open end of the chamber is located at the proximal end of the aerosol-generating device. In other embodiments, the longitudinal axis of the chamber is at an angle to the longitudinal axis of the aerosol-generating device, for example, transverse to the longitudinal axis of the aerosol-generating device. For example, the open end of the chamber is located along one side of the aerosol-generating device such that the aerosol-generating article can be inserted into the chamber in a direction perpendicular to the longitudinal axis of the aerosol-generating device.

[0030] As used herein, the term "proximal" refers to the user end of the aerosol generating device, or the mouth end of the aerosol generating device, and the term "distal" refers to the end opposite the proximal end. When referring to a chamber or inductor coil, the term "proximal" refers to the area closest to the open end of the chamber, and the term "distal" refers to the area closest to the closed end. The ends of the aerosol generating device or chamber may also be referred to in terms of the direction in which air flows through the aerosol generating device. The proximal end may be referred to as the "downstream end" and the distal end may be referred to as the "upstream end."

[0031] As used herein, the term "length" refers to the maximum longitudinal dimension of an aerosol generating device, an aerosol generating article, or a component of an aerosol generating device or a component of an aerosol generating article.

[0032] As used herein, the term "width" refers to the major transverse dimension of an aerosol-generating device, an aerosol-generating article, or a component of an aerosol-generating device, or a component of an aerosol-generating article, at a particular location along its length. The term "thickness" refers to the transverse dimension perpendicular to the width.

[0033] The term "aerosol-forming substrate" as used herein relates to a substrate capable of releasing volatile compounds capable of forming 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.

[0034] The term "aerosol-generating article" as used herein refers to an article that includes an aerosol-forming substrate capable of releasing a volatile compound capable of forming an aerosol. For example, the aerosol-generating article may be an article that generates an aerosol that can be directly inhaled by a user sucking or puffing on a mouthpiece at the proximal or user end of the system. The aerosol-generating article may be disposable. An article that includes an aerosol-forming substrate that includes tobacco is called a tobacco stick.

[0035] As used herein, the term "aerosol-generating device" refers to a device that interacts with an aerosol-generating article to generate an aerosol.

[0036] As used herein, the term "aerosol-generating system" refers to the combination of an aerosol-generating article as further described and illustrated herein with an aerosol-generating device as further described and illustrated herein, in which the aerosol-generating article and the aerosol-generating device cooperate to generate a respirable aerosol.

[0037] As used herein, the term "elongated" refers to a component that has a length that is greater than (eg, twice as great as) both its width and thickness.

[0038] As used herein, "susceptor element" means a conductive element that heats up when subjected to a varying magnetic field. This can be the result of eddy currents induced in the susceptor element, hysteresis losses, or both eddy currents and hysteresis losses. In use, the susceptor element is positioned in thermal contact or thermal proximity with an aerosol-forming substrate of an aerosol-generating article received in the chamber of an aerosol-generating device. In this manner, the aerosol-forming substrate is heated by the susceptor element, resulting in the formation of an aerosol.

[0039] Advantageously, providing multiple elongated susceptor elements spaced apart from one another may facilitate uniform heating of the aerosol-forming substrate across the width of the aerosol-generating article. Uniform heat distribution may result in more consistent aerosol characteristics and more efficient use of the aerosol-forming substrate. The use of different susceptors having differences such as different dimensions, shapes, or materials allows for sequential heating of different parts of the aerosol-forming substrate, which may also facilitate more efficient use of the aerosol-forming substrate. By heating the aerosol-forming substrate more efficiently, the power required to heat the aerosol-forming substrate may be reduced relative to existing systems. This may increase the efficiency of the device according to the invention. This may reduce battery size or increase battery life for a given battery size. This may facilitate a more compact arrangement.

[0040] The plurality of elongated susceptor elements may be spaced apart from one another across the chamber.The plurality of elongated susceptor elements may be spaced apart from one another along a plane perpendicular to the longitudinal axis of the chamber.

[0041] By providing more uniform heating across the width of the aerosol-generating article, the width or thickness, or width and thickness, of each individual susceptor element may be reduced, which may advantageously reduce the force required to insert the aerosol-generating article into the chamber. Reducing the width or thickness, or width and thickness, of each individual susceptor element may reduce the amount of aerosol-forming substrate displaced during insertion, thereby reducing or eliminating the need to clean the chamber after use.

[0042] Furthermore, in embodiments in which the chamber and aerosol-generating article of the aerosol-generating device have circular cross-sections, the arrangement of the claimed elongated susceptor elements may reduce or prevent unintended rotation of the aerosol-generating article within the chamber that could otherwise cause damage to the heater.

[0043] The use of induction heating has the advantage that the heating element (in this case the susceptor element) does not need to be electrically coupled to any other components, eliminating the need for solder or other coupling elements for the heating element. Furthermore, the inductor coil is provided as part of the aerosol generating device, allowing a simple, inexpensive and robust aerosol generating article to be constructed. Aerosol generating articles are generally disposable and are manufactured in much larger quantities than the aerosol generating devices they operate with. Thus, the reduced cost of the aerosol generating article, even when more expensive equipment is required, can lead to significant cost savings for both manufacturers and consumers.

[0044] Furthermore, due to the power losses associated with resistive coils, particularly losses due to contact resistance at the connection between the resistive coil and the power source, the use of inductive heating rather than resistive coils may provide improved energy conversion.

[0045] Advantageously, the use of an inductor coil rather than a resistive coil may extend the life of the aerosol generating device as the inductor coil itself experiences minimal heating during use of the aerosol generating device.

[0046] The elongated susceptor elements may be arranged such that their respective longitudinal axes are at an angle to one another, i.e., the elongated susceptor elements may be non-parallel. In a preferred embodiment, the elongated susceptor elements are substantially parallel to one another.

[0047] As used herein, the term "substantially parallel" means within plus or minus 10 degrees, preferably within plus or minus 5 degrees.

[0048] The plurality of elongated susceptor elements extend along the longitudinal axis of the chamber. That is, at least a portion of each susceptor element preferably extends substantially parallel to the longitudinal axis of the chamber. Advantageously, this facilitates insertion of at least a portion of the elongated susceptor element into the aerosol-generating article when the aerosol-generating article is inserted into the chamber. The plurality of elongated susceptor elements may be arranged such that their longitudinal axes are at an angle to, i.e., non-parallel to, the longitudinal axis of the chamber. One or more of the plurality of elongated susceptor elements may be substantially parallel to the longitudinal axis of the chamber.

[0049] In a preferred embodiment, the plurality of elongated susceptor elements are substantially parallel to the longitudinal axis of the chamber, such that the susceptor elements can be more easily inserted into the aerosol-generating article when the aerosol-generating article is inserted into the chamber.

[0050] The magnetic axis of the inductive element, e.g., the inductor coil, may be at an angle to the longitudinal axis of the chamber, i.e., non-parallel. In a preferred embodiment, the magnetic axis of the inductor coil is substantially parallel to the longitudinal axis of the chamber. This may facilitate a more compact arrangement. Preferably, at least a portion of each elongated susceptor element is substantially parallel to the magnetic axis of the inductor coil. This may facilitate uniform heating of the elongated susceptor elements by the inductor coil. In a particularly preferred embodiment, the plurality of elongated susceptor elements are substantially parallel to the magnetic axis of the inductor coil and the longitudinal axis of the chamber.

[0051] One or more of the plurality of elongated susceptor elements may be at least partially coincident with the longitudinal axis of the chamber. For example, one or more of the plurality of elongated susceptor elements may be at an angle to the longitudinal axis of the chamber and may pass through the longitudinal axis of the chamber at a location along its length. Alternatively, or in addition, one or more of the plurality of elongated susceptor elements may be parallel to the longitudinal axis of the chamber and centrally positioned within the chamber so as to extend along the longitudinal axis of the chamber.

[0052] In a preferred embodiment, each of the plurality of elongated susceptor elements is spaced from the longitudinal axis of the chamber. As such, the plurality of elongated susceptor elements are spaced from each other and from the longitudinal axis of the chamber. This can facilitate uniform heat distribution across the chamber, and therefore across the width of the aerosol-generating article received within the chamber.

[0053] When the elongated susceptor elements are spaced apart from the longitudinal axis of the chamber, one or more of the elongated susceptor elements may be spaced a different distance from the longitudinal axis than one or more of the other elongated susceptor elements, which may enable the aerosol-generating device to more uniformly heat an asymmetric aerosol-forming substrate.

[0054] In a preferred embodiment, the elongated susceptor elements are equidistant from the longitudinal axis of the chamber, i.e., the distance of each of the elongated susceptor elements from the longitudinal axis is the same at a given position along the length of the susceptor element. This may facilitate uniform heating of a symmetric aerosol-forming substrate by distributing heat evenly across the width of the chamber. It may also avoid the need to insert the aerosol-generating article into the chamber in a specific orientation, as would be the case for an asymmetric aerosol-forming substrate where the susceptor elements are at different distances from the longitudinal axis.

[0055] The plurality of elongated susceptor elements may include any suitable number of susceptor elements projecting into the chamber. The number of susceptor elements may be selected based on, for example, the size of the chamber, the size, geometry, and composition of the susceptor elements, and the size and composition of the aerosol-forming substrate intended for use with the aerosol-generating device. For example, the plurality of elongated susceptor elements may consist of two elongated susceptor elements spaced apart across the chamber.

[0056] In certain embodiments, the plurality of elongated susceptor elements includes three or more elongated susceptor elements. For example, the plurality of elongated susceptor elements may include three, four, five, six, seven, eight, nine, ten or more elongated susceptor elements. In such embodiments, the plurality of elongated susceptor elements may be spaced apart from one another in a single transverse direction such that they extend along substantially the same plane. This may allow for more uniform heating of the aerosol-forming substrate compared to an arrangement consisting of two elongated susceptor elements. Alternatively, the plurality of elongated susceptor elements may be spaced apart in a first transverse direction of the chamber and in a second transverse direction of the chamber perpendicular to the first transverse direction. In this manner, the plurality of elongated susceptor elements are spaced apart over an area. This may result in particularly uniform heating of the aerosol-forming substrate of the aerosol-generating article received in the chamber.

[0057] When the plurality of elongated susceptor elements includes three or more elongated susceptor elements, the three or more elongated susceptor elements may be spaced apart from one another in an irregular pattern with non-uniform spacing between one or more pairs of adjacent susceptor elements. The plurality of elongated susceptor elements may be arranged in a configuration in which each susceptor element is located at the vertices of a polygon having sides of unequal length, unequal corner angles, or unequal sides and corner angles. For example, the plurality of elongated susceptor elements may consist of four elongated susceptor elements located at the vertices of a rectangle, trapezoid, diamond, kite, arranged on a single circle, or in another other irregular configuration.

[0058] In a preferred embodiment, the plurality of elongated susceptor elements may be arranged in a regular pattern. As used herein, the term "regular pattern" is used to mean a pattern comprising a consistently spaced arrangement of the elongated susceptor elements. For example, the elongated susceptor elements may be arranged in a regular stripe pattern, a regular grid or square pattern, a regular brick pattern, a regular honeycomb or tortoise shell pattern, or any other regular geometric pattern. The arrangement of the plurality of elongated susceptor elements may be selected based on the cross-sectional shape of the inductor coil, or vice versa.

[0059] The inductor coil may have a circular cross-sectional shape. The inductor coil may have a non-circular cross-sectional shape. For example, the inductor coil may have an elliptical, triangular, square, rectangular, trapezoidal, rhombus, diamond, kite-shaped, pentagonal, hexagonal, octagonal, octagonal, decagonal, or any other polygonal cross-sectional shape. The inductor coil may have a regular polygonal cross-sectional shape. For example, an equilateral triangle, square, regular pentagon, regular hexagon, regular heptagon, regular octagon, regular nonagon, or regular decagon.

[0060] The plurality of elongated susceptor elements may be arranged in a configuration in which each susceptor element is located at a vertex of a regular polygon, i.e., at the vertices of an equiangular and equilateral polygon. This may allow for more consistent heating across an area of ​​the chamber. For example, if the plurality of elongated susceptor elements includes three elongated susceptor elements, they may be arranged in a triangular configuration, such as an equilateral triangle configuration. If the plurality of elongated susceptor elements includes four elongated susceptor elements, they may be arranged in a square configuration.

[0061] The plurality of elongated susceptor elements protrude into the chamber. Preferably, each of the elongated susceptor elements has a free end protruding into the chamber. Preferably, the free end is configured for insertion into the aerosol-generating article when the aerosol-generating article is inserted into the chamber. Preferably, one or more of the free ends of the plurality of elongated susceptor elements are tapered. This means that the cross-sectional area of ​​a portion of the elongated susceptor element decreases in a direction towards the free end. Advantageously, the tapered free end facilitates insertion of the elongated susceptor element into the aerosol-generating article. Advantageously, the tapered free end may reduce the amount of aerosol-forming substrate displaced by the elongated susceptor element during insertion of the aerosol-generating article into the chamber. This may reduce the amount of cleaning required. In a preferred embodiment, each of the plurality of elongated susceptor elements is tapered at its free end. Preferably, each of the plurality of elongated susceptor elements is tapered at its free end towards a sharp tip.

[0062] The aerosol generating apparatus includes a plurality of elongated susceptor elements that protrude into the chamber. The aerosol generating apparatus may further include non-elongated susceptor elements within the chamber. The aerosol generating apparatus may further include one or more external susceptor elements. The external susceptor elements are configured to remain outside of the aerosol-generating article received in the chamber. For example, the one or more external susceptor elements may extend at least partially around the periphery of the aerosol-generating article when received in the chamber.

[0063] The elongated susceptor elements may be formed from any material that can be inductively heated to a temperature sufficient to aerosolize the aerosol-forming substrate. Suitable materials for the elongated susceptor elements include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Preferred elongated susceptor elements include metal or carbon. Advantageously, each elongated susceptor element may include or consist of a ferromagnetic material, such as ferritic iron, ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrite. Suitable elongated susceptor elements may be or include aluminum. It is preferred that the elongated susceptor elements include more than 5%, preferably more than 20%, more preferably more than 50% or more than 90% ferromagnetic or paramagnetic material. Preferred elongated susceptor elements may be heated to a temperature of more than 250 degrees Celsius.

[0064] One or more of the elongated susceptor elements may be formed from a single layer of material, which may be a layer of steel.

[0065] The elongated susceptor elements may include a non-metallic core having a metallic layer disposed thereon. For example, one or more of the elongated susceptor elements may include a ceramic core or a metallic track formed on an outer surface of the substrate.

[0066] One or more of the susceptor elements may be formed from a layer of austenitic steel. One or more layers of stainless steel may be disposed on the layer of austenitic steel. For example, one or more of the susceptor elements may be formed from a layer of austenitic steel having a layer of stainless steel on each of its upper and lower sides.

[0067] Each of the elongated susceptor elements may include a first susceptor material and a second susceptor material. The first susceptor material is disposed in close physical contact with the second susceptor material. The first susceptor material and the second susceptor material may be in close contact to form a unitary susceptor. In a particular embodiment, the first susceptor material is stainless steel and the second susceptor material is nickel. One or more of the susceptor elements may have a bi-layer structure. Such a susceptor element may be formed from a stainless steel layer and a nickel layer.

[0068] The adhesion between the first susceptor material and the second susceptor material may be achieved by any suitable means. For example, the second susceptor material may be plated, evaporated, coated, clad or welded onto the first susceptor material. Preferred methods include electroplating, galvanic plating and cladding.

[0069] The Curie temperature of the second susceptor material may be lower than 500°C. The first susceptor material may be primarily used to heat the susceptor when it is placed in an alternating electromagnetic field. Any suitable tobacco material may be used. For example, the first susceptor material may be aluminum or a ferrous material such as stainless steel. The second susceptor material is preferably primarily used to indicate when the susceptor has reached a certain temperature, the temperature being the Curie temperature of the second susceptor material. The Curie temperature of the second susceptor material may be used to regulate the temperature of the entire susceptor during operation. Thus, the Curie temperature of the second susceptor material should be lower than the ignition point of the aerosol-forming substrate. Suitable materials for the second susceptor material may include nickel and certain nickel alloys. The Curie temperature of the second susceptor material may be preferably selected to be lower than 400°C, and may preferably be lower than 380°C or lower than 360°C. The second susceptor material is preferably a magnetic material selected to have a Curie temperature that is substantially the same as the desired maximum heating temperature. That is, the Curie temperature of the second susceptor material is preferably approximately the same as the temperature to which the susceptor should be heated to generate an aerosol from the aerosol-forming substrate. The Curie temperature of the second susceptor material may be, for example, in the range of 200° C. to 400° C., or 250° C. to 360° C. In some embodiments, it may be preferred that the first susceptor material is in the form of a strip having a width of 3 mm to 6 mm and a thickness of 10 micrometers to 200 micrometers, and the second susceptor material is in the form of a discontinuous patch that is plated, evaporated, or welded onto the first susceptor material. For example, the first susceptor material may be a strip of grade 430 stainless steel, or a strip of aluminum, and the second material may be in the form of patches of nickel 5 micrometers to 30 micrometers thick deposited at intervals along the strip of first susceptor material. The patches of second susceptor material may have a width between 0.5 mm and the thickness of the strip. For example, the width may be 1 mm to 4 mm, or 2 mm to 3 mm.The patch of second susceptor material may be from 0.5 mm to about 10 mm in length, preferably from 1 mm to 4 mm or from 2 mm to 3 mm.

[0070] In some embodiments, it may be preferred that the first susceptor material and the second susceptor material are laminated together in the form of a strip having a width of 3 mm to 6 mm and a thickness of 10 micrometers to 200 micrometers. The first susceptor material is preferably thicker than the second susceptor material. The laminating together may be by any suitable means. For example, the strip of first susceptor material may be welded or diffusion bonded to the strip of second susceptor material. Alternatively, the layer of second susceptor material may be evaporated or plated onto the strip of first susceptor material.

[0071] In some embodiments, it may be preferred that each elongated susceptor has a width of 3 mm to 6 mm and a width of 10 micrometers to 200 micrometers, the susceptor comprising a core of a first susceptor material encapsulated by a second susceptor material. Thus, each susceptor may comprise a strip of a first susceptor material coated or clad with a second susceptor material. As an example, the susceptor may comprise a strip of grade 430 stainless steel having a length of 12 mm, a width of 4 mm, and a thickness of 10 micrometers to 50 micrometers (e.g., 25 micrometers). The grade 430 stainless steel may be coated with a layer of nickel having a thickness of 5 micrometers to 15 micrometers (e.g., 10 micrometers).

[0072] One or more of the elongated susceptor elements may include a first susceptor material, a second susceptor material, and a protective layer. The first susceptor material is disposed in physical contact with the second susceptor material. The protective layer may be disposed in physical contact with one or both of the first susceptor material and the second susceptor material. The first and second susceptor materials and the protective layer may be in contact to form a unitary susceptor. The protective layer may be a layer of austenitic steel. In certain embodiments, one or more of the elongated susceptor elements comprises a layer of steel, a layer of nickel, and a protective layer of austenitic steel. The protective layer of austenitic steel may be applied to the nickel layer. This may help protect the nickel layer from adverse environmental effects such as oxidation, corrosion, diffusion, etc.

[0073] The elongated susceptor elements may be formed from the same material. Alternatively, one or more of the elongated susceptor elements may include a susceptor material or materials having different susceptor properties relative to at least one of the other susceptor elements. This may facilitate fine tuning of the heat distribution. This may also facilitate sequential heating of the susceptor elements, such as by forming the susceptor elements from materials for which optimal heating occurs at different frequencies of the alternating current.

[0074] The elongated susceptor elements may have any suitable cross-section. For example, the elongated susceptor elements may have a square, oval, rectangular, triangular, pentagonal, hexagonal or similar cross-sectional shape. The elongated susceptor elements may have a planar or flat cross-sectional area.

[0075] The elongated susceptor elements may be solid, hollow or porous. Each of the elongated susceptor elements is preferably solid. Each of the susceptor elements is preferably in the form of a pin, rod, blade or plate. The length of each of the susceptor elements is preferably 5 millimeters to 15 millimeters, for example 6 millimeters to 12 millimeters, or 8 millimeters to 10 millimeters. The width of each of the susceptor elements is preferably 1 millimeter to 8 millimeters, more preferably about 3 millimeters to about 5 millimeters. The thickness of each of the susceptor elements may be about 0.01 millimeters to about 2 millimeters. When the susceptor element has a constant cross-section, for example a circular cross-section, it preferably has a preferred width or diameter of 1 millimeter to 5 millimeters.

[0076] The plurality of elongated susceptor elements may have substantially the same length, i.e., the length of each of the elongated susceptor elements may be plus or minus 10 percent, preferably plus or minus 5 percent, of the length of the other elongated susceptor elements. The length of one or more of the plurality of elongated susceptor elements may be different from the length of the other elongated susceptor elements. The plurality of elongated susceptor elements may all have different lengths.

[0077] The plurality of elongated susceptor elements may have substantially the same width, i.e., the width of each elongated susceptor element may be plus or minus 10 percent, preferably plus or minus 5 percent, of the width of the other elongated susceptor elements. The width of one or more of the plurality of elongated susceptor elements may be different from the width of the other elongated susceptor elements. The plurality of elongated susceptor elements may all have different widths.

[0078] The plurality of elongated susceptor elements may have substantially the same thickness, i.e., the thickness of each of the elongated susceptor elements may be plus or minus 10 percent, preferably plus or minus 5 percent, of the thickness of the other elongated susceptor elements. The thickness of one or more of the plurality of elongated susceptor elements may be different from the thickness of the other elongated susceptor elements. The plurality of elongated susceptor elements may all have different thicknesses.

[0079] Each elongated susceptor element may have a protective outer layer, such as a protective ceramic or glass layer. The protective outer layer may encapsulate the elongated susceptor element. Each elongated susceptor element may include a protective coating formed of glass, ceramic, or an inert metal formed over a core of susceptor material.

[0080] The aerosol generating device is preferably portable. The aerosol generating device may be comparable in size to a conventional cigar or cigarette. The aerosol generating device may have a total length of about 30 mm to about 150 mm. The aerosol generating device may have an outer diameter of about 5 mm to about 30 mm.

[0081] The aerosol generating device housing may be elongated. The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composites containing one or more of these materials, or thermoplastics suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. Preferably, the material is lightweight and not brittle.

[0082] The housing may comprise a mouthpiece. The mouthpiece may comprise at least one air inlet and at least one air outlet. The mouthpiece may comprise two or more air inlets. One or more of the 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.

[0083] Alternatively, the mouthpiece may be provided as part of the aerosol-generating article.

[0084] As used herein, the term "mouthpiece" refers to a portion of an aerosol generating device that is placed in a user's mouth to directly inhale aerosol generated by the aerosol generating device from an aerosol-generating article received in the chamber of the housing.

[0085] The aerosol generating device may include a user interface for activating the aerosol generating device, such as a button to initiate heating of the aerosol generating device, or a display indicating the status of the aerosol generating device or the aerosol-forming substrate.

[0086] The aerosol generating device may include a power source. The power source may be a battery, such as a rechargeable lithium ion battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging. The power source may have a capacity that allows for the storage of sufficient energy for one or more uses of the aerosol generating device. For example, the power source may have a capacity sufficient to allow continuous production of aerosol for approximately six minutes, or a multiple of six minutes, corresponding to the typical time it takes to smoke one conventional cigarette. In another embodiment, the power source may have a capacity sufficient to allow a predetermined number of puffs, or discontinuous activation.

[0087] The power source may be a DC power source, hi 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 amp to about 10 amps (corresponding to a DC power range of about 2.5 watts to about 45 watts).

[0088] The power source may be configured to operate at a high frequency. As used herein, the term "high frequency oscillating current" refers to an oscillating current having a frequency between 500 kilohertz and 30 megahertz. The high frequency oscillating current may have a frequency between about 1 megahertz and about 30 megahertz, preferably between about 1 megahertz and about 10 megahertz, and more preferably between about 5 megahertz and about 8 megahertz.

[0089] The aerosol generating device includes a controller and a power supply connected to the inductor coil. The controller is configured to control the power supply from the power supply to the inductor. The controller may comprise a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application specific integrated circuit chip (ASIC) or other electronic circuit capable of providing control. The controller may comprise further electronic components. The controller may be configured to regulate the current supply to the inductor coil. The current may be continuously supplied to the inductor coil after activation of the aerosol generating device, or may be intermittently supplied (such as after every puff). The electrical circuit may advantageously comprise a DC / AC inverter, which may comprise a class D or class E power amplifier.

[0090] One or more of the plurality of elongated susceptor elements may be fixedly attached to the housing of the aerosol generation device In such embodiments, the fixedly attached susceptor element may not, for example, be easily removed from the aerosol generation device housing without damaging the susceptor element or the housing.

[0091] Advantageously, one or more of the plurality of elongated susceptor elements may be removably attached to the housing. For example, one or more of the plurality of elongated susceptor elements may be removably attached to the housing in the chamber. The susceptor elements are part of the aerosol generating device that is heated and therefore exhibit a short lifespan. Thus, providing a removable elongated susceptor element may allow the elongated susceptor element to be easily replaced and the lifespan of the aerosol generating device to be extended. Also, advantageously, providing a removable elongated susceptor element may facilitate cleaning of the susceptor element, replacement of the susceptor element, or both. This may also facilitate cleaning of the chamber. It may be possible for the susceptor element to be selectively replaced by a user depending on the aerosol generating article with which it is used. For example, a particular susceptor element may be adapted or tailored for use with a particular type of aerosol generating article or with an aerosol generating article having a particular arrangement or type of aerosol-forming substrate. This may allow for optimization of the performance of the aerosol generating device used with the susceptor element based on the type of aerosol generating article.

[0092] The plurality of elongated susceptor elements may be removably attached to the housing. In such embodiments, the plurality of elongated susceptor elements may be removably attached to the housing by any suitable mechanism, such as by a threaded connection, by frictional engagement, or by a bayonet, clip, or equivalent mechanical connection. The plurality of susceptor elements may be removable from the aerosol generating device individually or together with one or more of the other elongated susceptor elements.

[0093] The plurality of elongated susceptor elements may be attached to the housing directly or via one or more intermediate components. The plurality of elongated susceptor elements may be attached to a base portion configured for removable attachment to the aerosol generating device. The elongated susceptor elements may extend perpendicularly from the base portion. This may facilitate insertion of the elongated susceptor elements into the aerosol generating device.

[0094] The base portion may be configured for detachable connection to a housing of the aerosol generating device by at least one of an interference fit, a BNC terminal, and a threaded connector. The base portion may be configured for releasable attachment to the housing by magnetic attachment. Advantageously, magnetic attachment provides a simple and effective mechanism for releasably attaching the elongated susceptor element to the aerosol generating device.

[0095] The base portion may include a permanent magnet and the aerosol generating device may include a ferromagnetic material at the upstream end of the chamber. The base portion may include a ferromagnetic material and the aerosol generating device may include a permanent magnet at the upstream end of the chamber. Advantageously, providing a permanent magnet in only one of the base portion and the aerosol generating device may result in simplified and less expensive manufacture of the aerosol generating device.

[0096] The base portion may include a permanent magnet and the aerosol generating device may include a permanent magnet at the upstream end of the chamber. Advantageously, providing permanent magnets in both the base portion and the aerosol generating device may improve the strength of the magnetic attachment compared to an embodiment including only a single permanent magnet. Advantageously, the permanent magnet in the base portion and the permanent magnet in the aerosol generating device may each be oriented such that the attractive force between the two permanent magnets results in a desired orientation of the elongated susceptor element when the elongated susceptor element is inserted into the chamber.

[0097] In embodiments in which the base portion is configured for releasable attachment to the housing by magnetic attachment, the aerosol generating device may be combined with a removal tool for removing the elongated susceptor elements from the chamber. Preferably, the removal tool is sized for insertion into the chamber and includes a permanent magnet on an end of the removal tool. The permanent magnet on the end of the removal tool provides an attractive force between the removal tool and the base portion that is greater than the attractive force between the base portion and the aerosol generating device. Preferably, the removal tool includes a single recess or multiple recesses for receiving one or more of the elongated susceptor elements when the removal tool is inserted into the chamber.

[0098] Preferably, the housing includes an opening at an end of the chamber for insertion of the aerosol-generating article into the chamber. Preferably, the base portion is sized and shaped for insertion of the elongated susceptor element and the base portion into the chamber through the opening. Advantageously, this may eliminate the need for a separate opening to facilitate insertion of the elongated susceptor element into the chamber.

[0099] Preferably, the cross-sectional shape of the base portion is substantially the same as the cross-sectional shape of the chamber. The base portion may have a substantially circular cross-sectional shape.

[0100] The plurality of elongated susceptor elements may be removable from the base portion. Advantageously, this may facilitate reuse of the base portion with the plurality of elongated susceptor elements. This may be desirable because build-up of deposits may occur more quickly on the elongated susceptor elements than on the base portion.

[0101] According to a second aspect of the present invention, there is provided a removable susceptor assembly for an aerosol generating device according to the first aspect of the present invention, according to any of the embodiments described herein, wherein the removable susceptor assembly includes a base portion configured to be removably attached to a housing. A plurality of elongated susceptor elements are attached to the base portion such that when the base portion is removably coupled to the housing, the plurality of elongated susceptor elements protrude into the chamber. This may facilitate insertion of the elongated susceptor elements into the aerosol generating device. The base portion may be configured to detachably connect to the housing of the aerosol generating device by at least one of an interference fit, a BNC terminal, and a threaded connector. The base portion may be configured for removable attachment to the housing by magnetic attachment. Advantageously, the magnetic attachment provides a simple and effective mechanism for removably attaching the elongated susceptor elements to the aerosol generating device. The base portion may include a permanent magnet for removably attaching the base portion to the base portion of the housing of the aerosol generating device.

[0102] The plurality of elongated susceptor elements may be removable from the base portion. Advantageously, this may facilitate reuse of the base portion with the plurality of elongated susceptor elements. This may be desirable because build-up of deposits may occur more quickly on the elongated susceptor elements than on the base portion.

[0103] According to a further aspect of the present invention, there is provided an aerosol generation system comprising an aerosol generating device according to the alternative aspect of the present invention and an aerosol-generating article having an aerosol-forming substrate configured for use in the aerosol generating device.

[0104] According to a still further aspect of the invention there is provided an aerosol generation system comprising an aerosol generating device and an aerosol-generating article having an aerosol-forming substrate configured for use in the aerosol generating device, the aerosol generating device comprising a housing having a chamber sized to receive at least a portion of the aerosol-generating article, an inductor coil arranged around at least a portion of the chamber, and a controller connected to a power source and to the inductor coil, the aerosol generating system further comprising a plurality of elongated susceptor elements positioned such that when the aerosol-generating article is received in the chamber the plurality of elongated susceptor elements extend along a longitudinal axis of the chamber and are spaced apart from one another, the power source and controller configured to provide an alternating current to the inductor coil such that, in use, the inductor coil generates an alternating magnetic field to heat the plurality of elongated susceptor elements and thereby heat at least a portion of the aerosol-generating article.

[0105] The plurality of elongated susceptor elements may be positioned such that, when the aerosol-generating article is received in the chamber, the plurality of elongated susceptor elements are spaced apart from one another across the chamber.

[0106] The plurality of elongated susceptor elements may be provided as part of an aerosol generation apparatus, in such an embodiment, the aerosol generation apparatus may be substantially as described herein in relation to the first aspect of the invention.

[0107] The plurality of elongated susceptor elements may be provided as part of an aerosol-generating article. The plurality of elongated susceptor elements may be in thermal proximity to the aerosol-forming substrate. The plurality of elongated susceptor elements may be embedded within the aerosol-forming substrate. The form, type, distribution and arrangement of the plurality of elongated susceptor elements may be selected according to the needs of a user. The plurality of elongated susceptor elements may be substantially longitudinally arranged within the aerosol-generating article. This means that the length dimension of each of the elongated susceptor elements may be arranged approximately parallel to the longitudinal axis of the aerosol-generating article, for example within ±10 degrees of parallel to the longitudinal axis of the aerosol-generating article.

[0108] Advantageously, by providing more uniform heating of the aerosol-forming substrate, the size of the individual susceptor elements may be reduced. When these are provided as part of an aerosol-generating article, the volume occupied by the smaller susceptor elements is reduced. This may increase the amount of aerosol-forming substrate within an aerosol-generating article of a given size. This may allow for improved aerosol properties of the aerosol-generating article. The size of the aerosol-generating article may be reduced for a given amount of aerosol-forming substrate.

[0109] When a plurality of elongated susceptor elements are provided as part of an aerosol-generating article, the elongated susceptor elements are preferably in the form of pins, rods, blades or plates. The length of each of the elongated susceptor elements is preferably between 5 mm and 15 mm, for example between 6 mm and 12 mm, or between 8 mm and 10 mm. The width of each of the susceptor elements is preferably between 1 mm and 8 mm, preferably between about 3 mm and about 5 mm. The thickness of each of the elongated susceptor elements may be between 0.01 mm and 2 mm, for example between 0.5 mm and 2 mm. When each of the elongated susceptor elements has a constant cross-section, for example a circular cross-section, it has a preferred width or diameter of between 1 mm and 5 mm.

[0110] The elongated susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-forming substrate. Preferred susceptor elements include metal or carbon. Suitable susceptor elements may include ferromagnetic materials, such as ferritic iron, or ferromagnetic steel or stainless steel. Suitable susceptor elements may be or include aluminum. Preferred susceptor elements may be formed from 400 series stainless steel, such as grade 410, or grade 420, or grade 430 stainless steel. Different materials dissipate different amounts of energy when positioned in a magnetic field having similar values ​​of frequency and field strength. Thus, the parameters of the elongated susceptor element, such as material type, length, width, and thickness, may all be altered during manufacture to provide the desired power dissipation in a known magnetic field.

[0111] The plurality of susceptor elements may be provided as part of both the aerosol generating device and the aerosol generating article, for example the plurality of elongated susceptor elements may include a plurality of elongated susceptor elements forming part of the aerosol generating device and one or more elongated susceptor elements forming part of the aerosol generating article.

[0112] The aerosol generating system may be an electrically operated smoking system. The system may be a handheld aerosol generating system. The aerosol generating system may be comparable in size to a conventional cigar or cigarette. The overall length of the smoking system may be between about 30 mm and about 150 mm. The outer diameter of the smoking system may be between about 5 mm and about 30 mm.

[0113] An aerosol generating system may be a combination of an aerosol generating device and one or more aerosol generating articles for use with the aerosol generating device, however, the aerosol generating system may also include additional components, such as a charging unit for recharging an on-board power source within an electrically powered or electric aerosol generating device.

[0114] The aerosol-forming substrate of any aspect described herein may comprise nicotine. The nicotine-containing aerosol-forming substrate may be a nicotine salt matrix. The aerosol-forming substrate may comprise a plant-derived material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a tobacco-containing material comprising volatile tobacco flavour compounds that are released from the aerosol-forming substrate upon heating. Alternatively, the aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may comprise a homogenized plant-derived 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 an assembly of crimped sheets of homogenized tobacco material. As used herein, the term "crimped sheet" refers to a sheet having a plurality of substantially parallel ridges or wrinkles.

[0115] The aerosol-forming substrate may include at least one aerosol former. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense, stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperature of the system. Suitable aerosol formers are known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, and glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate and dimethyl tetradecanedioate). A preferred aerosol former is a polyhydric alcohol or mixtures thereof (such as triethylene glycol, 1,3-butanediol, and the like). Preferably, the aerosol former is glycerin. When present, the aerosol former content of the homogenized tobacco material is 5 percent or more on a dry weight basis, and preferably between 5 percent and 30 percent by weight on a dry weight basis. The aerosol-forming substrate may contain other additives and ingredients, such as flavourants.

[0116] In any of the above-described embodiments, the aerosol-generating article and the chamber of the aerosol-generating device may be arranged such that the aerosol-generating article is partially received within the chamber of the aerosol-generating device. The chamber of the aerosol-generating device and the aerosol-generating article may be arranged such that the aerosol-generating article is entirely received within the chamber of the aerosol-generating device.

[0117] The aerosol-generating article may be substantially cylindrical in shape. The aerosol-generating article may be substantially elongated. The aerosol-generating article may have a length and a circumference substantially perpendicular to the length. The aerosol-forming substrate may be provided as an aerosol-forming segment comprising an aerosol-forming substrate. The aerosol-forming segment may be substantially cylindrical in shape. The aerosol-forming segment may be substantially elongated. The aerosol-forming segment may have a length and a circumference substantially perpendicular to the length.

[0118] The aerosol-generating article may have an overall length of about 30 mm to about 100 mm. In one embodiment, the overall length of the aerosol-generating article is about 45 mm. The outer diameter of the aerosol-generating article may be about 5 mm to about 12 mm. In one embodiment, the aerosol-generating article may have an outer diameter of about 7.2 mm.

[0119] The aerosol-forming substrate may be provided as an aerosol-forming segment having a length of about 7 millimeters to about 15 millimeters. In one embodiment, the aerosol-forming segment may have a length of approximately 10 mm. Alternatively, the aerosol-forming segment may have a length of approximately 12 millimeters.

[0120] The aerosol-generation segment preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The outer diameter of the aerosol-forming segment may be from approximately 5 millimeters to approximately 12 millimeters. In one embodiment, the aerosol-forming segment may have an outer diameter of approximately 7.2 millimeters.

[0121] The aerosol-generating article may include a filter plug. The filter plug may be located at a downstream end of the aerosol-generating article. The filter plug may be a cellulose acetate filter plug. In one embodiment, the filter plug is about 7 millimeters long, but may have a length of about 5 millimeters to about 10 millimeters.

[0122] The aerosol-generating article may comprise an outer paper wrapper. Additionally, the aerosol-generating article may comprise a separation between the aerosol-forming substrate and the filter plug. The separation may be approximately 18 millimeters, but may range from approximately 5 millimeters to approximately 25 meters.

[0123] Features described with respect to one or more aspects may be equally applicable to the other aspects of the invention.

[0124] The aerosol generating systems described herein may include any of the following features.

[0125] The aerosol generating device may include a housing having a chamber sized to receive at least a portion of an aerosol-generating article, an inductor coil arranged around at least a portion of the chamber, a plurality of elongated susceptor elements protruding into the chamber, extending in a longitudinal direction of the chamber and spaced apart from one another, and a power source and controller connected to the inductor coil and configured to provide an alternating current to the inductor coil such that, in use, the inductor coil generates an alternating magnetic field to heat the plurality of elongated susceptor elements, thereby heating at least a portion of the aerosol-generating article received in the chamber.

[0126] The aerosol generating device may include a plurality of elongated susceptor elements that are substantially parallel to one another.

[0127] The aerosol generating device may include a plurality of elongated susceptor elements substantially parallel to the longitudinal axis of the chamber.

[0128] The aerosol generating device may include a plurality of elongated susceptor elements, each spaced apart from the longitudinal axis of the chamber.

[0129] The aerosol generating device may include a plurality of elongated susceptor elements equidistant from the longitudinal axis of the chamber.

[0130] The aerosol generating device may include a plurality of elongated susceptor elements, including three or more elongated susceptor elements spaced apart in a first transverse direction of the chamber and in a second transverse direction of the chamber perpendicular to the first transverse direction.

[0131] The aerosol generating device may include three or more elongated susceptor elements arranged in a regular pattern.

[0132] The aerosol generating device may include a plurality of elongated susceptor elements, each of which is tapered at its free end.

[0133] The aerosol generating device may include a plurality of elongated susceptor elements removably mounted to a housing.

[0134] A removable susceptor assembly for an aerosol generating device may include a plurality of elongated susceptor elements and a base portion configured to be removably attached to a housing of the aerosol generating device, where the plurality of elongated susceptor elements are attached to the base portion such that when the base portion is removably attached to the housing, the plurality of elongated susceptor elements protrude into a chamber.

[0135] An aerosol generating system may comprise an aerosol generating device as described anywhere herein and an aerosol-generating article having an aerosol-forming substrate configured for use in the aerosol generating device.

[0136] The aerosol generating system may comprise an aerosol generating device and an aerosol generating article having an aerosol-forming substrate and configured for use with the aerosol generating device, the aerosol generating device comprising a housing having a chamber sized to receive at least a portion of the aerosol generating article, an inductor coil arranged around at least a portion of the chamber, and a power source and controller connected to the inductor coil, wherein the aerosol generating system further comprises a plurality of elongated susceptor elements arranged such that, in use, the plurality of elongated susceptor elements extend in the longitudinal direction of the chamber and are spaced apart from one another, and the power source and controller are configured to provide an alternating current to the inductor coil such that, in use, the inductor coil generates an alternating magnetic field to heat the plurality of elongated susceptor elements, thereby heating at least a portion of the aerosol generating article.

[0137] The aerosol generating system may comprise a plurality of elongated susceptor elements provided as part of an aerosol generating device.

[0138] The aerosol generating system may comprise a plurality of elongated susceptor elements provided as part of an aerosol generating article. The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0139] [Figure 1] FIG. 1 is a schematic cross-sectional view of an aerosol generation system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a side perspective view of the aerosol generation system of FIG. 1, also showing the inductor coil and susceptor element. [Diagram 3] FIG. 3 is an end perspective view of the aerosol generation system of FIG. [Figure 4] FIG. 4 is an end view of the inductor coil and susceptor element of the aerosol generation system of FIG. 1 with all other components omitted for clarity. [Diagram 5] FIG. 5 is a schematic cross-sectional view of an aerosol generation system according to a second embodiment of the present invention. [Figure 6] FIG. 6 is a side perspective view of the aerosol generation system of FIG. 5, also showing the inductor coil and susceptor element. [Figure 7] FIG. 7 is a perspective end view of the aerosol generation system of FIG. [Figure 8] FIG. 8 is an end view of the inductor coil and susceptor element of the aerosol generation system of FIG. 5 with all other components omitted for clarity. [Figure 9] FIG. 9 is a schematic cross-sectional view of an aerosol generation system according to one embodiment of the present invention. [Figure 10] FIG. 10 is a schematic end view showing one possible susceptor configuration for the aerosol generating system of FIG. [Figure 11] FIG. 11 is a schematic end view showing one further possible susceptor configuration for the aerosol generating system of FIG. [Figure 12] FIG. 12 is a schematic end view showing one further possible susceptor configuration for the aerosol generating system of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0140] Figure 1 shows a schematic cross-sectional view of an aerosol generating system according to a first embodiment of the present invention. The aerosol generating system comprises an aerosol generating device 100 according to the first embodiment and an aerosol-generating article 10 configured for use in the aerosol generating device 100. Figures 2, 3 and 4 show different views of the aerosol generating device 100.

[0141] The aerosol-forming article 10 includes an aerosol-forming segment 20 at its distal end. The aerosol-forming segment 20 contains an aerosol-forming substrate, such as a plug including tobacco material and an aerosol former, that can be heated to generate an aerosol.

[0142] The aerosol generating device 100 comprises a device housing 110 that defines a chamber 120 for receiving the aerosol generating article 10. The proximal end of the housing 110 has an insertion opening 125 through which the aerosol generating article 10 can be inserted into and removed from the chamber 120. The inductor coil 130 is disposed within the aerosol generating device 100 between the outer wall of the housing 110 and the chamber 120. The inductor coil 130 is a helical inductor coil having a magnetic axis that corresponds to the longitudinal axis of the chamber 120, which in this embodiment corresponds to the longitudinal axis of the aerosol generating device 100. As shown in FIG. 1, the inductor coil 130 is located adjacent to a distal portion of the chamber 120, which in this embodiment extends along a portion of the length of the chamber 120. In other embodiments, the inductor coil 130 may extend along the entire or substantially the entire length of the chamber 120, or may extend along a portion of the length of the chamber 120 and be located away from the distal portion of the chamber 120. For example, the inductor coil 130 may extend along a portion of the length of the chamber 120 and adjacent a proximal portion of the chamber 120. The inductor coil 130 is formed from a wire and has multiple turns or turns extending along its length. The wire may have any suitable cross-sectional shape, such as square, oval, or triangular. In this embodiment, the wire has a circular cross-sectional shape. In other embodiments, the wire may have a flat cross-sectional shape. For example, the inductor coil may be formed from a wire having a rectangular cross-sectional shape and wound such that the maximum width of the wire's cross section extends parallel to the magnetic axis of the inductor coil. Such a flat inductor coil may allow the outer diameter of the inductor, and therefore the outer diameter of the aerosol generating device, to be minimized.

[0143] The aerosol generating device 100 also includes an internal power source 140 (e.g., a rechargeable battery) and a controller 150 (e.g., a printed circuit board having circuitry), both located in a distal region of the housing 110. Both the controller 150 and the inductor coil 130 receive power from the power source 140 via electrical connections (not shown) that extend through the housing 110. Preferably, the chamber 120 is separated from the inductor coil 130 and the distal region of the housing 110 containing the power source 140 and the controller 150 by a liquid-tight separator. Thus, the electrical components within the aerosol generating device 100 may remain separated from the aerosol or residue generated within the chamber 120 by the aerosol generation process. This may also facilitate cleaning of the aerosol generating device 100, as the chamber 120 may be completely emptied by simply removing the aerosol generating components. This configuration may also reduce the risk of damage to the aerosol-generating device, either during insertion of the aerosol-generating article or during cleaning, since potentially fragile elements are not exposed within the chamber 120. Ventilation holes (not shown) may be provided in the walls of the housing 110 to allow airflow into the chamber 120. Alternatively, or additionally, airflow may enter the chamber 120 at the opening 125 and flow along the length of the chamber 120 between the outer wall of the aerosol-generating article 10 and the inner wall of the chamber 120.

[0144] The aerosol generating device 100 also includes a susceptor assembly 160 located within the chamber 120. The susceptor assembly 160 includes a base portion 170 and two elongated susceptor elements 180 attached to the base portion 170 and projecting into the chamber 120. The elongated susceptor elements 180 are mutually parallel to the longitudinal axis of the chamber 120 and the magnetic axis of the inductor coil 130.

[0145] As best seen in Figures 2, 3 and 4, the susceptor elements 180 are uniformly spaced apart from the longitudinal axis of the chamber 120 with gaps in the transverse direction. The susceptor elements 180 are located within a portion of the chamber 120 surrounded by the inductor coil 130 and are inductively heated by the inductor coil 130. Each of the susceptor elements 180 tapers toward its free end to form a sharp tip. This may facilitate inserting the susceptor elements 180 into an aerosol-generating article received within the cavity. In this embodiment, the base portion 170 is secured within the chamber 120 and the susceptor elements 180 are secured to the base portion 170. In other embodiments, the base portion 170 may be removably coupled to the housing 110 to allow the susceptor assembly 160 to be removed from the chamber 120 as a single component. For example, base portion 170 may be removably coupled to housing 110 using a removable clip (not shown), a threaded connection, or a similar mechanical connection.

[0146] When the aerosol generating device 100 is operated, a high frequency alternating current is passed through the inductor coil 130 to generate an alternating magnetic field within the distal end portion of the chamber 120 of the aerosol generating device 100. The frequency of the magnetic field varies between 1 and 30 MHz, preferably between 2 and 10 MHz, for example between 5 and 7 MHz. When the aerosol-generating article 10 is properly positioned within the chamber 120, the susceptor element 180 is located within the aerosol-forming substrate 20 of the aerosol-generating article. The varying electromagnetic field generates eddy currents within the susceptor element 180, which in turn heats up. Further heating is provided by magnetic hysteresis losses within the susceptor element 180. The heated susceptor element 180 heats the aerosol-forming substrate 20 of the aerosol-generating article 10 to a temperature sufficient to form an aerosol. The aerosol is drawn downstream through the aerosol-generating article 10 and can be inhaled by a user. Such actuation may be manual, or may occur automatically in response to a user inhaling the aerosol-generating article 10, for example, by use of a puff sensor.

[0147] The aerosol generating device may further include a magnetic flux concentrator (not shown) located around the inductor coil 130 and formed from a material having a high relative magnetic permeability, such that the magnetic field generated by the inductor coil 130 is attracted to and guided by the magnetic flux concentrator. In this manner, the magnetic flux concentrator may limit the extent to which the magnetic field generated by the inductor coil 130 extends beyond the housing 110, and may increase the density of the magnetic field within the chamber 120. This may increase the current generated within the susceptor element to allow for more efficient heating. Such a magnetic flux concentrator may be made of any suitable material or materials having a high relative magnetic permeability. For example, the magnetic flux concentrator may be formed from one or more ferromagnetic materials (e.g., ferrite materials, ferrite powder held in a binder, etc.), or any other suitable material including ferrite materials such as ferritic iron, ferromagnetic steel, or stainless steel. The magnetic flux concentrator is preferably made from a material or materials having a high relative magnetic permeability. It is a material that has a relative permeability of at least 5 (e.g., 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) when measured at 25 degrees Celsius. These exemplary values ​​may refer to the relative permeability of the magnetic flux concentrator material for frequencies between 6 and 8 MHz and a temperature of 25 degrees Celsius.

[0148] Figure 5 shows a schematic cross-sectional view of an aerosol generating system according to a second embodiment of the invention. The aerosol generating system comprises an aerosol generating device 200 according to the second embodiment and an aerosol-generating article 10 configured for use in the aerosol generating device 200. Figures 6, 7 and 8 show different views of the aerosol generating device 200.

[0149] The aerosol generating device 200 of the second embodiment is similar to the aerosol generating device 100 of the first embodiment in terms of structure and operation, and similar reference numbers are used where identical features exist. However, unlike the aerosol generating device 100 of the first embodiment, the aerosol generating device 200 has an inductor assembly 260 including three elongated susceptor elements 280 attached to a base portion 270. The three susceptor elements 280 are arranged in a regular pattern. In particular, the susceptor elements 280 are arranged such that each susceptor element 280 is located at the apex of an equilateral triangle. In this manner, the plurality of elongated susceptor elements 280 are spaced apart both in a first transverse direction of the chamber and in a second transverse direction of the chamber perpendicular to the first transverse direction. This means that the plurality of elongated susceptor elements 280 are spaced apart across the area of ​​the chamber 120, each extending along a different plane. This may result in more uniform heating of the aerosol-forming substrate of the aerosol-generating article received within the chamber.

[0150] Figure 9 shows a schematic cross-sectional view of an aerosol generation system according to one embodiment of the present invention. The embodiment shown in Figure 9 is similar to the embodiment described above in relation to Figure 1. Therefore, the components of the system that are the same as those described above in relation to Figure 1 are given the same reference numerals and the relevant description will not be repeated. Figure 10 shows an end view of the aerosol generation device 100 of Figure 9, revealing the configuration of the two susceptors 960, 980.

[0151] The embodiment of Figure 9 differs from the embodiment of Figure 1 in that the aerosol generating device 100 includes an inductive element 930 having two separately operable inductive coils. The first inductive coil 931 is configured to generate an alternating magnetic field having a frequency between 3 and 5 MHz, and the second inductive coil 932 is configured to generate an alternating magnetic field having a frequency between 7 and 10 MHz. The first inductive coil 931 and the second inductive coil 932 are coupled to the controller 150 and can be operated separately and sequentially.

[0152] The aerosol generating device further comprises two elongated susceptor elements 960, 980 arranged to protrude into the chamber. The first susceptor element 960 is configured to heat more efficiently than the second susceptor element 980 when the first induction coil 931 is activated. Thus, the first susceptor element is configured to heat to a temperature higher than 300 degrees Celsius when the first induction coil 931 is activated, and the second susceptor element is configured to heat to a temperature lower than 300 degrees Celsius when the first induction coil is activated. In use, this means that an aerosol can be generated from the aerosol-forming substrate adjacent to the first susceptor element, rather than from a portion of the aerosol-forming substrate adjacent to the second susceptor element. Conversely, the second susceptor element 980 is configured to heat more efficiently than the first susceptor element 960 when the second induction coil 932 is activated. Thus, the second susceptor element is configured to heat to a temperature above 300 degrees Celsius when the second induction coil 932 is activated, and the first susceptor element is configured to heat to a temperature below 300 degrees Celsius when the second induction coil is activated. In use, this means that the aerosol is generated from the aerosol-forming substrate adjacent to the second susceptor element, rather than from a portion of the aerosol-forming substrate adjacent to the first susceptor element.

[0153] By sequentially activating the first susceptor element and the second susceptor element, sequential heating of different portions of the aerosol-forming substrate can be achieved.

[0154] There are many parameters that can be altered to tune each susceptor element to operate more efficiently at any particular frequency of the alternating magnetic field: for example, shape, size, permeability and resistivity can all be altered to change the way eddy currents are generated within the susceptor and the efficiency of heating.

[0155] As an example, Figure 10 shows an end view of two susceptors 960 and 980. The susceptors are in the form of elongated blades with a longitudinal dimension greater than a width dimension greater than a thickness dimension. The longitudinal dimension is 10 mm, the width dimension is 3 mm, and the thickness dimension is 1 mm. The first susceptor 960 may be formed from grade 430 stainless steel and the second susceptor may be formed from a graphite material.

[0156] Further examples of different configurations of susceptor elements are shown in Figures 11 and 12. In Figure 11, a first susceptor 1160 is formed from an elongated blade of grade 430 stainless steel and a second susceptor 1180 is formed from an elongated tube of grade 430 stainless steel. In Figure 12, a first susceptor 1260 is formed from an elongated square cross-section rod of aluminum and a second susceptor 1280 is formed from an elongated circular cross-section rod of aluminum.

[0157] One skilled in the art can vary the size, shape, and materials to form different susceptor elements that produce different heating responses to alternating magnetic fields of different frequencies.

[0158] The above exemplary embodiments are not intended to limit the scope of the claims, and other embodiments consistent with the above exemplary embodiments will be apparent to those skilled in the art.

Claims

1. 1. An aerosol generation system comprising: An aerosol generating device (100), comprising: A housing (110); a heating chamber (120) defining a heating zone, said heating chamber (120) being sized to receive at least a portion of the aerosol-forming substrate within said heating zone; an inductive element (130) disposed around said heating zone; Power supply, one or more external susceptor elements; a controller connected to the inductive element and configured to provide an alternating current to the inductive element to generate an alternating magnetic field in the heating zone, wherein the inductive element (130) is controlled to sequentially provide a first alternating magnetic field having a first frequency for a first period and then a second alternating magnetic field having a second frequency for a second period; the inductive element being a single coil configured to provide both the first alternating magnetic field and the second alternating magnetic field; Aerosol generation systems.

2. 2. The aerosol generating system of claim 1, wherein, in use, the first alternating magnetic field causes preferential heating of a first susceptor (180) located within the heating zone, and the second alternating magnetic field causes preferential heating of a second susceptor (180) located within the heating zone.

3. 3. The aerosol generating system of claim 2, wherein the first susceptor (180) is heated to a higher temperature than the second susceptor (180) during the first period and the second susceptor (180) is heated to a higher temperature than the first susceptor (180) during the second period, or the second susceptor (180) is heated to a higher temperature than the first susceptor (180) during the first period and the first susceptor (180) is heated to a higher temperature than the second susceptor (180) during the second period.

4. The aerosol generation system of claim 2 or 3, wherein the inductive element (130) can be controlled to provide three or more different alternating magnetic fields for three or more separate periods, each of the three or more alternating magnetic fields having a different frequency.

5. The aerosol generation system of claim 2 , wherein the aerosol generation device (100) comprises the first susceptor (180) and the second susceptor (180).

6. 6. The aerosol generating system of claim 5, wherein the aerosol generating device (100) includes a plurality of elongated susceptor elements protruding into the chamber (120), the plurality of elongated susceptor elements extending in the longitudinal direction of the chamber (120) and spaced apart from one another, and the plurality of elongated susceptor elements including at least the first susceptor (180) and the second susceptor (180).

7. The aerosol generating system of claim 6 , wherein the plurality of elongated susceptor elements are substantially parallel to one another.

8. 8. The aerosol generation system of claim 6 or 7, wherein the first and second susceptor elements (180), or each of the plurality of elongated susceptor elements, are removably attached to the aerosol generation device (100).

9. 9. The aerosol generation system of claim 8, comprising the first and second susceptor elements (180), or the plurality of elongated susceptor elements, and a base portion (170) configured to be removably attached to the housing (110) of the aerosol generating device (100), wherein the first and second susceptor elements, or the plurality of elongated susceptor elements, are attached to the base portion (170) such that the first and second susceptor elements, or the plurality of elongated susceptor elements, protrude into the heating chamber (120) when the base portion (170) is removably coupled to the housing (110).

10. 2. The aerosol generating system of claim 1, further comprising an aerosol-generating article (10), the aerosol-generating article (10) including the aerosol-forming substrate and dimensioned to be received by the heating chamber (120) such that at least a portion of the aerosol-forming substrate is within the heating zone.

11. 10. The aerosol generation system of claim 2, wherein the first susceptor (180) has a first shape, a first cross-section, a first length dimension, a first width dimension, and a first thickness dimension, and the second susceptor (180) has a second shape, a second cross-section, a second length dimension, a second width dimension, and a second thickness dimension, and at least one of the first and second shapes, first and second cross-sections, first and second length dimensions, first and second width dimensions, and first and second thickness dimensions are different.

12. The aerosol generating system of any one of claims 2 to 9 or 11, wherein the first susceptor (180) is formed from a first material and the second susceptor (180) is formed from a second material, the first material having one or more material properties different from the second material, the one or more properties including resistivity of the material and magnetic permeability of the material.

13. A method of using an aerosol generating system as defined in any one of claims 2 to 12, said method comprising the steps of: inserting an aerosol-generating article into the heating chamber (120) of the aerosol-generating device (100) such that at least a portion of the aerosol-forming substrate is located within the heating zone; activating the inductive element (130) to provide a first alternating magnetic field having a first frequency for a first time period, thereby preferentially heating a first susceptor (180) located within the heating zone for the first time period; and activating the inductive element (130) to provide a second alternating magnetic field having a second frequency for a second time period, thereby preferentially heating a second susceptor (180) located within the heating zone for the second time period; A method in which a first portion of the aerosol-forming substrate is heated by the first susceptor (180) for the first period of time, and a second portion of the aerosol-forming substrate is heated by the second susceptor (180) for the second period of time.

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