Induction heating module for use in an induction heating aerosol generator

Abstract

An induction heating module (30) for use in an induction heating aerosol generator (1) includes an induction coil (13) for inductively heating a susceptor (22) within an interior space of the induction coil to heat an aerosol-forming substrate in thermal contact or thermal proximity with the susceptor, the induction coil being formed by a coil wire. The induction heating module further includes a coil support (17) for supporting the induction coil, which includes a support tube (32), the induction coil being wound around the outer periphery of the support tube. The outer periphery of the support tube includes a wire recess pattern (39) into which the coil wire is received. A flux concentrator (50) is provided, the support tube including two recesses (38) for receiving at least a portion of the flux concentrator. An aerosol generator and an aerosol generation system including the induction heating module are also described.

Description

[Technical Field]

[0001] The present disclosure relates to an induction heating module for use in an inductively heated aerosol generating device. The present disclosure further relates to an aerosol generating device and an aerosol generating system comprising such an induction heating module. [Background technology]

[0002] Aerosol-generating devices and systems used to generate inhalable aerosols by inductively heating an aerosol-forming substrate are generally known in the prior art. Such systems and devices may comprise an induction heating arrangement including an induction coil for generating an alternating magnetic field. The magnetic field is used to induce at least one of heat-generating eddy currents or hysteresis losses in a susceptor disposed in thermal proximity or direct physical contact with the aerosol-forming substrate, which is capable of forming an inhalable aerosol upon heating. The susceptor and substrate may be part of an aerosol-generating article receivable within the interior space of the induction coil. Specifically, the substrate may be a liquid aerosol-forming substrate stored within a liquid reservoir of the article. The reservoir may be in fluid communication with a susceptor located within an evaporation portion of the article, and the aerosol-forming liquid may be evaporated by interaction of the susceptor with the alternating magnetic field of the induction coil. Alternatively, the aerosol-forming substrate may be a solid or gel-like aerosol-forming substrate in thermal proximity or direct physical contact with the susceptor, with both the susceptor and the substrate being contained within the evaporation portion of the article. Alternatively, the susceptor may also be part of the aerosol-generating device.

[0003] In some articles, the susceptor may have a flat shape, such as a sheet-like shape, that provides a large surface-to-mass ratio, which is beneficial not only for efficient utilization of the heat generated by the susceptor, but also for enhancing heat transfer from the susceptor to the aerosol-forming substrate.

[0004] During a user experience, the induction heating arrangement may be operated continuously or on demand, specifically in an intermittent mode such as after every puff. In a continuous operating mode, the susceptor is permanently maintained at a temperature level sufficient to form a satisfactory amount of aerosol, but when the heating system is operated intermittently, such as on user demand, achieving a sufficient temperature level within a short period of time can be a challenge.

[0005] It would therefore be desirable to have an induction heating module, an aerosol generator, and an aerosol generation system for inductively heating an aerosol-forming substrate that possesses the advantages of prior art solutions while mitigating their limitations. Specifically, it would be desirable to have an induction heating module, an aerosol generator, and an aerosol generation system for inductively heating an aerosol-forming substrate that is in thermal proximity or direct physical contact with a susceptor, particularly a flat susceptor such as a sheet-like susceptor, each of which allows for greater heating efficiency, particularly achieving sufficient temperature levels within a shorter period of time. Summary of the Invention

[0006] According to the present invention, there is provided an induction heating module for use in an induction heating aerosol generator. The induction heating module comprises at least one cylindrical helical induction coil, specifically a single cylindrical helical induction coil, for generating an alternating magnetic field capable of inductively heating a susceptor within the interior space of the induction coil to heat an aerosol-forming substrate in thermal contact or thermal proximity with the susceptor. The induction coil is formed by one or more turns of coil wire, preferably having a circular cross section. The induction heating module further comprises a coil support for supporting the induction coil, comprising a support tube, specifically a cylindrical support tube, the induction coil being wound around the outer periphery of the support tube. The outer periphery of the support tube comprises a wire recess pattern into which the coil wire is received.

[0007] According to the present invention, it has been found that the heating efficiency of an induction heating module intended to heat a susceptor within the interior space of a cylindrical spiral induction coil can be improved by reducing the radial distance between the induction coil and the location within the interior space of the induction coil where the susceptor is located during use. In the present invention, this is achieved by providing a wire recess pattern on the outer periphery of the support tube, into which the coil wire is received. The wire recess pattern allows the induction coil to be located closer to the susceptor location. The reduced radial distance leads to an increase in magnetic field strength at the susceptor location, which in turn causes an increase in heating efficiency. Therefore, the level of heat generated within the susceptor for a given level of power passing through the induction coil is increased, which, among other things, allows the desired temperature level to be reached within a shorter period of time. In addition, it has been experimentally found that a coil wire with a circular cross section facilitates susceptor heating in terms of both heating efficiency and the time it takes to reach the desired temperature level.

[0008] The use of coil wire with a circular cross section has several advantages. It is commercially available, therefore readily available, and non-expanding. It has good winding characteristics. Most importantly, for high frequency applications, particularly for induction heating purposes such as in the present invention, it helps to reduce undesirable ring / crossover effects.

[0009] The efficiency of the induction heating module is further enhanced due to the use of a cylindrical helical induction coil, which advantageously makes it possible to generate a homogeneous alternating magnetic field.

[0010] Preferably, the interior space of the support tube forms a receiving cavity for removably receiving at least a portion of the aerosol-generating article, specifically the evaporation portion of the aerosol-generating article. The evaporation portion of the article may comprise a susceptor, specifically a flat susceptor, more specifically a sheet-like susceptor, for heating an aerosol-forming substrate contained within the article by interaction of the susceptor with the alternating magnetic field of the induction coil when the article, specifically the evaporation portion, is received within the interior space of the support tube. That is, the susceptor inductively heated by the induction coil may be part of the aerosol-generating article. Alternatively, the susceptor inductively heated by the induction coil may be part of an aerosol-generating device in / with which the induction heating module is configured to be used.

[0011] Preferably, the induction coil comprises only a single winding layer of one or more turns of coil wire. It has been found that induction of a single layer of one or more turns of coil wire may be sufficient to achieve a sufficiently strong magnetic field at the susceptor. Nevertheless, it is also possible for the induction coil to comprise more than one winding layer, for example two or three layers.

[0012] The distance (center-to-center) between adjacent recesses in the wire recess pattern may be greater than the diameter of the coil wire. As a result, portions of the coil wire from adjacent turns do not come into contact with each other. This allows for the use of coil wire without wire insulation. Nevertheless, the coil wire may be insulated. For example, the coil wire may be coated copper wire, e.g., enamel-coated copper wire. In addition, the gap between adjacent turns of the induction coil serves for better heat dissipation and therefore leads to less resistive power loss in the coil winding. The gap between adjacent turns also helps to reduce undesirable ring / crossover effects.

[0013] The coil wire may be one of a solid wire, a stranded wire, and a litz wire.

[0014] Preferably, the distance between adjacent recesses (center-to-center) in the wire recess pattern is within the range of 1.1 to 1.4 times, specifically 1.2 to 1.3 times, the diameter of the coil wire. These ranges have been proven to provide a sufficiently large distance that still allows for a compact coil design, i.e., a sufficiently large number of turns per unit of length.

[0015] As further mentioned above, the induction coil is formed by one or more turns of coil wire. Preferably, the induction coil comprises 3 to 6 turns, particularly 4 to 5 turns. The number of turns does not necessarily have to be an integer; it can be any number between two integers.

[0016] Because induction coils are driven by AC current, the current through the coil wire flows only near the outer surface of the coil wire. Therefore, the diameter of the coil wire does not need to be large to carry a large current. To achieve a compact coil design with a sufficiently large number of turns per unit of length, it can be beneficial if the coil wire has a diameter in the range of 0.8 mm to 1.5 mm, specifically 1 mm to 1.2 mm.

[0017] Preferably, the induction coil has an axial length extension similar to the axial length extension of the susceptor measured in the same direction when received within the interior space of the induction coil. The induction coil may have an axial length in the range of 4 mm to 12 mm, specifically 5 mm to 8 mm.

[0018] According to the present invention, the coil wire is received in a wire recess pattern. To this extent, the wire recess pattern also serves to stabilize the coil winding. Consequently, the wire recess pattern is preferably selected to correspond to the desired winding pattern of the induction coil. Since the induction is a cylindrical spiral induction coil, the wire recess pattern is preferably also a spiral wire recess pattern.

[0019] The purpose of the wire recess pattern is to reduce the radial distance between the induction coil and the susceptor location within the internal space of the induction coil. As a result, the greater the recess depth of the wire recess pattern, the better the magnetic field strength at the susceptor location within the internal space of the induction coil. Preferably, the recess depth of the wire recess pattern in the radial direction is within the range of 0.2 to 0.8 times, specifically 0.3 to 0.5 times, the diameter of the coil wire.

[0020] The radial distance between the inner circumference of the support tube and the bottom of the recess pattern may be 0.1 mm to 1 mm, specifically 0.2 mm to 0.5 mm, and preferably about 0.3 mm. Similarly, the radial distance between the inner circumference of the induction coil and the inner circumference of the support tube may be 0.1 mm to 1 mm, specifically 0.2 mm to 0.5 mm, and preferably about 0.3 mm. These distance values have proven to be a good compromise between a sufficiently small radial distance between the induction coil and the susceptor location and a still sufficiently large minimum wall thickness of the support tube, which still ensures adequate mechanical stability of the support tube.

[0021] The coil support may include a circumferential collar at each axial end of the support tube to provide lateral axial restraint for the coil windings.

[0022] At least one of the collars may include a recess or feed-through opening for a passing connection lead for the induction coil.

[0023] When the induction heating module is intended to heat a flat, particularly sheet-like, susceptor, it may be advantageous to adapt the geometry of the magnetic field within the interior space of the induction coil in which the susceptor is placed to the flat shape of the susceptor. As a result, the outer periphery of the support tube may have a non-circular, flattened cross-sectional shape that includes, particularly consists of, two opposing flat sections connected by two opposing, at least partially curved sections. That is, the outer surface of the support tube along its periphery may comprise, particularly consist of, two opposing flat outer portions connected by two opposing, at least partially curved outer portions. In this configuration, the induction coil may be wound around the periphery of the support tube, such that the cross-sectional shape of the induction coil follows the non-circular, flattened cross-sectional shape of the periphery of the support tube. Advantageously, by flattening the transverse cross-sectional shape of the induction coil, the radial distance between the induction coil and the flat susceptor's major surfaces can be reduced, given that the susceptor is positioned so that its major surfaces are aligned with two opposing flat sections of the transverse cross-sectional shape of the support tube's outer periphery. The reduced radial distance leads to an increase in the magnetic field strength at the susceptor, which in turn causes an increase in heating efficiency. Therefore, the level of heat generated in the susceptor for a given level of power passing through the induction coil is increased, which, among other things, allows the desired temperature level to be reached within a shorter period of time.

[0024] The shape of the two at least partially curved sections or the shape of the two opposing at least partially curved outer portions, respectively, is selected to provide a smooth transition between the two opposing flat sections or the two opposing flat outer portions, respectively, which allows for smooth winding of the wire coil around the outer circumference of the support tube. Preferably, the at least partially curved section is one of substantially semicircular, substantially semi-elliptical, substantially semi-elliptical, or substantially parabolic.

[0025] In particular, each (respective end point of) two opposing flat sections (connecting two opposing flat sections) may abut (respective end points of) two opposing flat sections, so that the transition between two opposing flat sections or two opposing flat outer portions is particularly smooth.

[0026] Preferably, the non-circular flattened cross-sectional shape is an ellipse. Similarly, since the cross-sectional shape of the induction coil follows the non-circular flattened cross-sectional shape of the outer periphery of the support tube, the cross-sectional shape of the induction coil may also be an ellipse. As used herein, the term "ellipse" defines a shape consisting of two semicircles connected by parallel lines tangent to their endpoints.

[0027] As a result, the support tube and induction coil may have an oval cylindrical shape, i.e., a flattened cylinder shape having two opposing planar side wall portions parallel to each other and two opposing hemispherical side wall portions between the two opposing planar side wall portions.

[0028] Preferably, when the outer periphery of the support tube has a non-circular flattened transverse cross-sectional shape as described above, each of the collars, if present, may have a non-circular flattened transverse cross-sectional shape corresponding to the non-circular flattened transverse cross-sectional shape of the outer periphery of the support tube. Specifically, each collar may have an oval transverse cross-sectional shape.

[0029] For easy and inexpensive manufacture, the coil support may include or be made of plastic. If the induction heating module must meet certain regulatory requirements, the coil support may include or be made of bisphenol A-free plastic.

[0030] Additionally, the induction heating module may comprise a flux concentrator disposed around the induction coil and configured, in use, to distort the alternating magnetic field of the induction coil towards the interior space of the support tube.

[0031] Specifically, the flux concentrator may include a sleeve portion circumferentially surrounding the induction coil. Additionally, the flux concentrator may include annular protrusions at each axial end of the sleeve portion that protrude radially inward beyond the sleeve portion such that the induction coil is axially disposed between the annular protrusions. Advantageously, the annular protrusions at each axial end of the sleeve portion that protrude radially inward beyond the sleeve portion result in a concentration or focusing of the magnetic field within the interior space of the induction coil. Therefore, the level of heat generated within the susceptor for a given level of power passing through the induction coil is increased compared to an induction coil that does not have a flux concentrator or does not have annular protrusions at each axial end and only has a sleeve-shaped flux concentrator. This helps increase heating efficiency, specifically, to reach a desired temperature level within a shorter period of time. Additionally, the flux concentrator acts as a magnetic shield, capable of reducing the extent to which the magnetic field propagates beyond the induction coil.

[0032] Preferably, the flux concentrator comprises or is made of one or more layers of flux concentrator foil. According to a preferred setup of the flux concentrator, each of the annular protruding portions may be made of one or more layers of flux concentrator foil, which extend in a radially outward direction at least to, and preferably beyond, the outer periphery of the induction coil. On top of the annular protruding portions, a sleeve portion may be made of one or more layers of flux concentrator foil surrounding the induction coil and each of the annular protruding portions. According to an alternative setup of the flux concentrator, the sleeve portion may be made of one or more layers of flux concentrator foil surrounding the induction coil, while each of the annular protruding portions may be made of one or more layers of flux concentrator foil, terminating radially flush with the outer periphery of the sleeve portion.

[0033] At least one of the annular projecting portions, preferably the more distal annular projecting portion, may be provided with a recess or feed-through opening for a passing connection lead for the induction coil. If the flux concentrator is formed by rolling a flux concentrator foil, the recess or feed-through opening may be cut into the annular projecting portion after rolling the flux concentrator foil.

[0034] When the support tube and induction coil have a non-circular flattened cross-sectional shape as described above, the flux concentrator may also have a non-circular flattened cross-sectional shape corresponding to the non-circular flattened cross-sectional shape of the support tube and induction, i.e., the non-circular flattened cross-sectional shape comprises, or in particular consists of, two opposing flat sections connected by two opposing at least partially curved sections. In particular, the cross-sectional shape of the flux concentrator may be oval.

[0035] The outer periphery of the support tube may further comprise, for each annular protruding portion of the flux concentrator, a flux concentrator recess into which a radially inward end of the respective annular protruding portion is received, so that the annular protruding portions are securely supported, which helps to prevent the flux concentrator from being displaced, which may otherwise lead to an undesired change in the inductance of the induction coil and an undesired change in the magnetic field density in the interior space of the induction coil.

[0036] The present invention also relates to an inductively heated aerosol generating apparatus for use with an aerosol-generating article, the article comprising an aerosol-forming substrate that is heated by interaction of a susceptor with an alternating magnetic field provided by the aerosol generating apparatus, the aerosol generating apparatus comprising an inductive heating module according to the present invention and as described herein.

[0037] As used herein, the term "aerosol-generating device" is used to describe an electrically operated device capable of interacting with at least one aerosol-generating article comprising an aerosol-forming substrate, specifically an aerosol-forming liquid, and a susceptor, such as to generate an aerosol by inductively heating the substrate through interaction of the susceptor with an alternating magnetic field provided by the device. Preferably, the aerosol-generating device is a smoking device for generating an aerosol that can be directly inhaled by a user through the user's mouth. Specifically, the aerosol-generating device is a handheld aerosol-generating device.

[0038] The aerosol generating device may comprise a device housing in which the induction heating module according to the present invention is located or disposed.

[0039] The aerosol generating device, particularly the device housing, may be provided with an insertion opening providing access to the interior space of the induction coil or the interior space of the support tube of the induction heating module to allow insertion of an aerosol-generating article therein.

[0040] The aerosol-generating device may further comprise a receiving cavity for removably receiving at least a portion of the aerosol-generating article, specifically the evaporating portion. The receiving cavity may be located at least partially within the interior space of the induction coil or the interior space of the support tube of the induction heating module. Specifically, the receiving cavity may be at least partially formed by the interior space of the induction coil or the support tube of the induction heating module, specifically the interior space of the support tube of the induction heating module. The induction coil may be arranged to surround at least a portion of the receiving cavity, specifically at least the evaporating portion of the aerosol-generating article, when the aerosol-generating article is received within the receiving cavity.

[0041] The aerosol generating device may further include an alternating current (AC) generator. The AC generator may be powered by a power source, specifically a DC power supply of the device. The AC generator is operably coupled to at least one induction coil. Specifically, the induction coil may be an integral part of the AC generator. The AC generator is configured to generate a high-frequency oscillating current that passes through the induction coil to generate a varying magnetic field. The AC current may be supplied to the induction coil continuously after activation of the system, or may be supplied intermittently, such as after each puff.

[0042] Preferably, the aerosol generating device comprises a DC / AC converter connectable to a DC power source, which may be part of the aerosol generating device.

[0043] The DC / AC converter may include an LC network. For example, the DC / AC converter may include a power amplifier, specifically a switching power amplifier, more specifically a single-ended switching power amplifier, preferably one of a Class C power amplifier, a Class D power amplifier, or a Class E power amplifier. Specifically, the DC / AC converter may include at least one transistor switch, specifically a single transistor switch, at least one transistor switch driver circuit, and at least one LC network. The LC network may include a series connection of a capacitor and an inductor, the inductor being a cylindrical spiral induction coil of the induction heating module according to the present invention, which is used to generate an alternating magnetic field for heating a susceptor of an article received within the interior space of the induction coil. The LC network may further include a shunt capacitor in parallel with the transistor switch. In addition, the DC / AC converter may include a choke inductor for supplying a DC supply voltage from a DC power source.

[0044] The aerosol generating device is preferably configured to generate a high-frequency fluctuating magnetic field. As referred to herein, the high-frequency fluctuating magnetic field may have a frequency in the range of 500 kHz (kilohertz) to 30 MHz (megahertz), specifically 5 MHz (megahertz) to 15 MHz (megahertz), preferably 5 MHz (megahertz) to 10 MHz (megahertz).

[0045] The aerosol-generating device may further include a controller configured to control operation of the device. Specifically, the controller may be configured to control heating of the aerosol-forming substrate to a predetermined operating temperature. Depending on at least one of the type of aerosol-forming substrate being heated, the configuration of the susceptor, and the arrangement of the susceptor relative to the aerosol-forming substrate, the operating temperature may be in the range of 180°C to 370°C, specifically 180°C to 240°C, or 280°C to 370°C.

[0046] The controller may comprise a microprocessor, such as a programmable microprocessor, microcontroller, or application specific integrated circuit chip (ASIC) or other electronic circuitry capable of providing control. The controller may also comprise further electronic components, particularly portions of an alternating current (AC) generator, such as portions of a DC / AC inverter and / or power amplifier. In particular, the induction heating module may be, at least in part, part of the controller.

[0047] The aerosol generating device may further include a puff detector, such as a microphone or pressure sensor, for detecting a user puff, i.e., the onset of the user experience when the user begins to puff on the device. The puff detector may be operably connected to the controller, whereby detection of the occurrence of a puff by the puff detector may trigger delivery of power to the induction coil for generating the aerosol. That is, the controller may be configured to initiate operation of the heating arrangement, specifically generation of the alternating magnetic field, in response to the puff detector detecting the occurrence of a user puff.

[0048] The aerosol generating device may include a power source, specifically a DC power source configured to provide a DC supply voltage and a DC supply current to the induction heating module. Preferably, the power source is a battery, such as a lithium iron phosphate battery. The power source may have a capacity sufficient to allow continuous generation of aerosol for approximately six minutes, or a multiple of six minutes. Similarly, the power source may have a capacity sufficient to allow a predetermined number of puffs, or discontinuous activation of the induction heating module.

[0049] The susceptor used to heat the aerosol-forming substrate by interaction of the susceptor with the alternating magnetic field provided by the aerosol-generating device may be part of an article configured for use with the device. Specifically, the susceptor may be disposed within the evaporation portion of the article. In this configuration, the interior space of the induction coil, the interior space of the support tube of the induction heating module, and / or the receiving cavity of the aerosol-generating device are preferably configured to removably receive at least the evaporation portion of the aerosol-generating article.

[0050] Alternatively, the susceptor used to heat the aerosol-forming substrate by interaction of the susceptor with the alternating magnetic field provided by the aerosol-generating device may be part of the aerosol-generating device itself, i.e., the aerosol-generating device according to this embodiment (first embodiment) may comprise a susceptor for heating the aerosol-forming substrate.

[0051] In either configuration, the susceptor is preferably a flat susceptor, more particularly a sheet-like susceptor. The flat, particularly sheet-like, susceptor may comprise or be a susceptor blade, susceptor strip, or susceptor plate. Specifically, when the substrate is a liquid, i.e., an aerosol-forming liquid, the susceptor may comprise or be a mesh susceptor. It is also possible that the susceptor may comprise or be a susceptor sleeve, susceptor cup, cylindrical susceptor, or tubular susceptor.

[0052] Further features and advantages of the aerosol generating device according to this first aspect of the invention are described in relation to the induction heating module of the invention and apply equally.

[0053] The present invention further relates to an aerosol-generating system comprising an aerosol-generating device according to the invention and as described herein, and to an aerosol-generating article for use with the aerosol-generating device, the article comprising an aerosol-forming substrate that is heated by interaction of a susceptor with an alternating magnetic field provided by the aerosol-generating device.

[0054] As used herein, the term "aerosol-generating system" refers to the combination of an aerosol-generating article, as further described herein, and an aerosol-generating device according to the present invention and as described herein, in which the article and device cooperate to generate a respirable aerosol.

[0055] As used herein, the term "aerosol-generating article" refers to an article comprising at least one aerosol-forming substrate that, when heated, releases a volatile compound capable of forming an aerosol. The aerosol-generating article is preferably a heated aerosol-generating article, i.e., an aerosol-generating article comprising at least one aerosol-forming substrate that is intended to be heated, rather than combusted, to release a volatile compound capable of forming an aerosol. The aerosol-generating article may be a consumable product, specifically a consumable product that is discarded after a single use. Preferably, the article may comprise a liquid aerosol-forming substrate, i.e., an aerosol-forming liquid. Alternatively, the article may comprise a solid aerosol-forming substrate or a gel-like aerosol-forming substrate, or a combination thereof.

[0056] As used herein, the term "aerosol-forming substrate" generally refers to a substrate formed from or including an aerosol-forming material capable of releasing volatile compounds upon heating to generate an aerosol. The aerosol-forming substrate is intended to be heated, rather than combusted, to release the aerosol-forming volatile compounds. The aerosol-forming substrate may be a solid aerosol-forming substrate, a liquid aerosol-forming substrate, a gel-like aerosol-forming substrate, or any combination thereof. Preferably, the aerosol-forming substrate is a liquid aerosol-forming substrate, i.e., an aerosol-forming liquid. The aerosol-forming liquid may include both solid and liquid aerosol-forming materials or components. The aerosol-forming substrate, particularly the aerosol-forming liquid, may include a tobacco-containing material containing volatile tobacco flavor compounds that are released from the substrate upon heating. Alternatively, or additionally, the aerosol-forming substrate, particularly the aerosol-forming liquid, may include a non-tobacco material. The aerosol-forming substrate, particularly the aerosol-forming liquid, may further include an aerosol former. Examples of suitable aerosol formers are glycerin and propylene glycol. The aerosol-forming substrate, specifically the aerosol-forming liquid, may also contain other additives and ingredients, such as nicotine or flavorings. Specifically, the aerosol-forming liquid may contain water, a solvent, ethanol, a plant extract, and a natural or artificial flavor. The aerosol-forming liquid may be an aqueous aerosol-forming liquid or an oil-based aerosol-forming liquid. The aerosol-forming substrate may also be a paste-like material, a sachet of porous material containing the aerosol-forming substrate, or loose tobacco mixed with, for example, a gelling agent or adhesive, which may contain a common aerosol former, such as glycerin, which is compressed or molded into a plug.

[0057] As described above in relation to the aerosol-generating device according to the invention, the susceptor for heating the aerosol-forming substrate may be part of either the aerosol-generating device or the aerosol-generating article, i.e. either the aerosol-generating device or the aerosol-generating article comprises a susceptor for heating the aerosol-forming substrate.

[0058] In the latter case, the aerosol-generating article may comprise an evaporation portion, and a susceptor for heating the aerosol-forming substrate is disposed in the evaporation zone. In this configuration, the interior space of the induction coil of the aerosol-generating device and / or the interior space of the support tube of the induction heating module is preferably configured to removably receive at least the evaporation portion of the aerosol-generating article.

[0059] As used herein, the term "susceptor" refers to an element capable of converting electromagnetic energy into heat when subjected to a varying magnetic field. This may be the result of at least one of hysteresis loss or eddy currents induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material. Hysteresis loss occurs in ferromagnetic or ferrimagnetic susceptors due to magnetic domains in the susceptor material being switched under the influence of the varying magnetic field. Eddy currents may be induced if the susceptor is electrically conductive. In the case of an electrically conductive ferromagnetic or ferrimagnetic susceptor, heat can be generated due to both eddy currents and hysteresis loss.

[0060] As a result, the susceptor 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 susceptors include metal or carbon. Preferred susceptors may include ferromagnetic materials, such as ferritic iron, or ferromagnetic steel or stainless steel. Suitable susceptors may be or include aluminum. Preferred susceptors may be formed from 400 series stainless steel, such as grade 410, grade 420, or grade 430 stainless steel.

[0061] The susceptor may have a variety of geometric configurations depending, inter alia, on the type of aerosol-forming substrate.

[0062] The susceptor may include or be a susceptor pin, susceptor rod, susceptor blade, susceptor strip, or susceptor plate. Similarly, the susceptor may include or be a susceptor sleeve, susceptor cup, cylindrical susceptor, or tubular susceptor. Preferably, the susceptor is a flat susceptor, more particularly a sheet-like susceptor.

[0063] Specifically, when the substrate is a liquid, i.e., an aerosol-forming liquid, the susceptor may comprise or be a filament susceptor, a mesh susceptor, or a wick susceptor. In any of these configurations, the susceptor advantageously has the ability to perform both the functions of drawing (delivering) and heating the aerosol-forming liquid. As a result, in any of the foregoing configurations, the susceptor may be considered a liquid-delivery susceptor.

[0064] If the aerosol-forming substrate is a liquid substrate, the article may comprise a liquid reservoir for storing the aerosol-forming liquid. Preferably, the susceptor is in fluid communication with the liquid reservoir in which the aerosol-forming liquid is stored.

[0065] Further features and advantages of the aerosol generation system are described with respect to the induction heating module and aerosol generator of the present invention and apply equally.

[0066] As used herein, the terms "radial" and "axial" refer to the cylindrical geometry of a cylindrical induction coil.

[0067] Example Ex1: An induction heating module for use in an induction heated aerosol generator, comprising: a cylindrical helical induction coil for generating an alternating magnetic field within the interior space of the induction coil that allows inductive heating of a susceptor in order to heat an aerosol-forming substrate that is in thermal contact or thermal proximity with the susceptor, the induction coil being formed by one or more turns of a coil wire, the coil wire preferably having a circular cross section; - a coil support for supporting an induction coil comprising a support tube, wherein the induction coil is wound around the outer periphery of the support tube and the internal space of the support tube forms a receiving cavity for removably receiving at least an evaporation portion of an aerosol-generating article, wherein when the evaporation portion is received in the internal space of the support tube, the evaporation portion comprises a susceptor for heating an aerosol-forming substrate contained within the article by interaction between the susceptor and the alternating magnetic field of the induction coil, and the outer periphery of the support tube comprises a wire recess pattern into which the coil wire is received.

[0068] Example Ex1a: An induction heating module according to example Ex1, wherein the internal space of the support tube forms a receiving cavity for removably receiving at least a portion of an aerosol-generating article, in particular an evaporation portion of the aerosol-generating article, and wherein the evaporation portion of the article preferably comprises a susceptor, in particular a flat susceptor, more in particular a sheet-like susceptor, for heating an aerosol-forming substrate contained within the article by interaction of the susceptor with the alternating magnetic field of the induction coil.

[0069] Example Ex2: An induction heating module according to any one of example Ex1 or example Ex1a, wherein the distance between adjacent recesses of the wire recess pattern is greater than the diameter of the coil wire.

[0070] Example Ex3: An induction heating module according to any one of the preceding examples, wherein the distance between adjacent recesses of the wire recess pattern is in the range of 1.1 to 1.4 times, specifically 1.2 to 1.3 times, the diameter of the coil wire.

[0071] Example Ex4: An induction heating module according to any one of the preceding examples, wherein the induction coil comprises 3 to 6 turns, in particular 4 to 5 turns.

[0072] Example Ex5: An induction heating module according to any one of the preceding examples, wherein the coil wire has a diameter in the range of 0.8 millimeters to 1.5 millimeters, specifically 1 millimeter to 1.2 millimeters.

[0073] Example Ex6: An induction heating module according to any one of the preceding examples, wherein the wire recess pattern corresponds to the winding pattern of the induction coil.

[0074] Example Ex7: An induction heating module according to any one of the preceding examples, wherein the coil wire is one of a solid wire, a stranded wire, and a litz wire.

[0075] Example Ex8: An induction heating module according to any one of the preceding examples, wherein the wire recess pattern is a spiral wire recess pattern.

[0076] Example Ex9: An induction heating module according to any one of the preceding examples, wherein the depth of the recesses of the radial wire recess pattern is in the range of 0.2 to 0.8 times, specifically 0.3 to 0.5 times, the diameter of the coil wire.

[0077] Example Ex10: An induction heating module according to any one of the preceding examples, wherein the radial distance between the inner circumference of the support tube and the bottom of the recess pattern is in the range of 0.1 millimeter to 1 millimeter, specifically 0.2 millimeter to 0.5 millimeter, preferably about 0.3 millimeter.

[0078] Example Ex11: An induction heating module according to any one of the preceding examples, wherein the radial distance between the inner circumference of the induction coil and the inner circumference of the support tube is in the range of 0.1 millimeter to 1 millimeter, specifically 0.2 millimeter to 0.5 millimeter, preferably about 0.3 millimeter.

[0079] Example Ex12: An induction heating module according to any one of the preceding examples, wherein the coil support comprises a circumferential collar at each axial end of the support tube.

[0080] Example Ex13: An induction module according to example Ex12, wherein at least one of the collars comprises a recess or feed-through opening for a passing connection lead for the induction coil.

[0081] Example Ex14: An induction module according to any one of the preceding examples, wherein the coil support comprises or is made of plastic, in particular bisphenol A-free plastic.

[0082] Example Ex15: An induction module according to any one of the preceding examples, wherein the outer periphery of the support tube is provided with two flux concentrating recesses for receiving at least a respective portion of the flux concentrator, and the wire recess pattern is disposed axially between the two flux concentrating recesses.

[0083] Example Ex16: An induction module according to any one of the preceding examples, wherein the outer periphery of the support tube has a non-circular flattened transverse cross-sectional shape comprising, in particular consisting of, two opposing flat sections connected by two opposing at least partially curved sections, and wherein the induction coil is wound around the outer periphery of the support tube, whereby the transverse cross-sectional shape of the induction coil follows the non-circular flattened transverse cross-sectional shape of the outer periphery of the support tube.

[0084] Example Ex17: A guidance module according to example Ex16, wherein the non-circular flattened transverse cross-sectional shape of the outer periphery of the support tube has a minor axis of symmetry and a major axis of symmetry.

[0085] Example Ex18: An induction heating module according to example Ex17, in which the ratio of the maximum distance along the major axis of symmetry between two opposing at least partially curved sections to the maximum distance along the minor axis of symmetry between two opposing flat sections is in the range of 1.2 to 3, in particular 1.5 to 2.5.

[0086] Example Ex19: An induction heating module according to any one of examples Ex17 or Ex18, wherein the maximum distance along the minor axis of symmetry between two opposing flat sections is in the range of 4 millimeters to 7 millimeters, specifically 5 millimeters to 6 millimeters.

[0087] Example Ex20: An induction heating module according to any one of Examples Ex17 to Ex19, wherein the maximum distance along the longitudinal axis of symmetry between two opposing at least partially curved sections is in the range of 7 millimeters to 10 millimeters, specifically 8 millimeters to 9 millimeters.

[0088] Example Ex21: An induction heating module according to any one of examples Ex16 to Ex20, wherein the two opposing flat sections are parallel to each other.

[0089] Example Ex22: An induction heating module according to any one of examples Ex16 to Ex21, wherein each of the two opposing flat sections is substantially straight.

[0090] Example Ex23: An induction heating module according to any one of examples Ex16 to Ex22, wherein each of the at least partially curved sections is one of substantially semicircular, substantially semi-oval, substantially semi-elliptical, or substantially parabolic.

[0091] Example Ex24: The induction heating module according to any one of Examples Ex16 to Ex23, wherein the non-circular flattened transverse cross-sectional shape of the outer periphery of the support tube is oval.

[0092] Example Ex25: An induction heating module according to any one of Examples Ex16 to Ex24, in which the transverse cross-sectional shape of the induction coil is oval.

[0093] Example Ex26: An inductively heated aerosol generating apparatus for use with an aerosol-generating article, the article comprising an aerosol-forming substrate that is heated by interaction of a susceptor with an alternating magnetic field provided by the aerosol-generating apparatus, the apparatus comprising an inductive heating module according to any one of the preceding examples.

[0094] Example Ex27: An inductively heated aerosol-generating apparatus according to example Ex26, wherein the apparatus further comprises a susceptor for heating the aerosol-forming substrate.

[0095] Example Ex28: An induction-heated aerosol generator according to example Ex27, wherein the susceptor is a flat susceptor, more particularly a sheet-like susceptor.

[0096] Example Ex29: An aerosol-generating system comprising an aerosol-generating device according to any one of Examples Ex26 to Ex28 and an aerosol-generating article for use with the aerosol-generating device, the article comprising an aerosol-forming substrate that is heated by interaction of a susceptor with an alternating magnetic field provided by the aerosol-generating device.

[0097] Example Ex30: An aerosol-generating system according to example Ex29, wherein either the aerosol-generating device or the aerosol-generating article comprises a susceptor for heating the aerosol-forming substrate.

[0098] Example Ex31: An aerosol-generating system according to example Ex30, wherein the susceptor is a flat susceptor, more particularly a sheet-like susceptor.

[0099] Example Ex32: An aerosol-generating system according to any one of Examples Ex29 to Ex31, wherein the article comprises an evaporation portion and a susceptor for heating the aerosol-forming substrate is disposed in the evaporation zone.

[0100] Example Ex33: An aerosol generating system according to example Ex32, wherein the inner space of the induction coil of the induction heating module and / or the inner space of the support tube are configured to removably receive at least the evaporated portion of the aerosol-generating article.

[0101] The embodiments will now be further described with reference to the figures. [Brief explanation of the drawings]

[0102] [Figure 1] FIG. 1 shows an exemplary embodiment of an aerosol generation system according to the present invention in longitudinal cross section. [Figure 2] FIG. 2 shows a detailed longitudinal cross-section of the aerosol generation system according to FIG. [Figure 3] FIG. 3 shows a detail of the aerosol generation system according to FIG. 1 in a longitudinal perspective cross-sectional view. [Figure 4] FIG. 4 shows details of the coil support used in the aerosol generating device according to FIG. [Figure 5] FIG. 5 shows details of an induction heating arrangement used in the aerosol generating device according to FIG. [Figure 6] FIG. 6 shows further details of the coil support used in the aerosol generating device according to FIG. [Figure 7] FIG. 7 shows details of a first embodiment of power electronics that can be used in the aerosol generating device according to FIG. [Figure 8] FIG. 8 shows details of a second embodiment of power electronics that can alternatively be used in the aerosol generating device according to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0103] 1-3 show schematic cross-sectional views of an aerosol-generation system 1 according to an exemplary embodiment of the present invention. System 1 is configured to generate an inhalable aerosol by inductively heating a susceptor in thermal contact with a liquid aerosol-forming substrate 25, hereinafter also referred to as aerosol-forming liquid 25. System 1 comprises two main components: an aerosol-generating article 2 and an aerosol-generation device 1 for use with article 2. Article 2 includes a susceptor 22 and an aerosol-forming liquid 25 to be heated, while device 1 comprises a receiving cavity 16 for receiving article 2 and an induction heating arrangement 10 configured to generate an alternating magnetic field for inductively heating susceptor 22 and thus vaporizing the aerosol-forming liquid 25 in article 2 when the latter is inserted into cavity 16 of device 1.

[0104] 1 , which shows the device 1 and the article 2 disconnected from each other, the aerosol generating device 1 comprises a substantially rod-shaped main body having a substantially cylindrical device housing 15. Within the distal portion 4, the device 1 comprises a power source 12, e.g., a lithium-ion battery, and an electrical circuit 11 including a controller 160 for controlling the operation of the device 1, and in particular for controlling the heating process. Within the proximal portion 5 opposite the distal portion 4, the device 1 comprises a receiving cavity 16 and at least a portion of the induction heating arrangement 10. The receiving cavity 16 is an open cavity with an insertion opening 19 at the proximal end of the device 1 to allow insertion of the article 2 into the receiving cavity 16.

[0105] The induction heating arrangement 10 includes an induction coil 13 for generating an alternating magnetic field within the cavity 16. The induction coil 13 is a cylindrical, helical coil that circumferentially surrounds the cylindrical receiving cavity 16. In this embodiment, the induction coil 13 has an axial length of approximately 8 millimeters and is formed by a single layer of 4.25 turns of a coil wire having a circular cross section. The turns of the induction coil 13 extend along the length of the cavity 16. Preferably, there is a gap between adjacent turns of the induction coil 13. That is, the pitch of the helical induction coil 13 may be greater than the diameter of the coil wire. As a result, adjacent turns of the coil wire do not contact each other, which allows the use of coil wire without wire insulation. Nevertheless, the coil wire in this embodiment is an enamel-coated copper wire with a diameter of 1.1 millimeters. In addition, the gap between adjacent turns of the induction coil serves for better heat dissipation and therefore leads to less resistive power loss in the coil winding. In this embodiment, the distance (center to center) between adjacent portions of the coil wire of adjacent turns is about 1.1 times the diameter of the coil wire. These ranges have been proven to provide a sufficiently large distance that still allows for a compact coil design, i.e., a sufficiently large number of turns per unit of length.

[0106] The induction coil 13 is part of the induction module 30, which, in addition to the induction coil 13, further comprises a coil support 17 disposed within the device housing 15 for supporting the induction coil 13. Details of the coil support 17 are shown in FIG. 4. The coil support 17 comprises a cylindrical support tube 32 and circumferential collars 33 at each axial end of the support tube 32. The more distal collars 33 include recesses or feed-through openings 34 for connection leads 60 to pass through to the induction coil 13, as shown in FIG. 5. As can be seen from FIGS. 1-3, the interior space of the support tube 32 at least partially defines the receiving cavity 16 of the device 1 for removably receiving at least a portion of the aerosol-generating article 2. That is, the inner surface of the support tube 32 along its inner circumference forms at least a portion of the inner surface of the receiving cavity 16. For simple and inexpensive manufacture, the coil support 17 may be made of plastic. If the induction heating module 30 must comply with certain regulatory requirements, the coil support 17 may be made of, for example, a bisphenol A-free plastic.

[0107] In addition to induction coil 13, induction heating arrangement 10 includes power electronics that may be at least partially integrated within electrical circuit 11 and coupled to induction coil 13 via connecting electrical pads 131 (see FIG. 1 ). In combination with induction coil 13, power electronics function to generate a high-frequency alternating current that passes through induction coil 13, which causes induction coil 12 to generate a high-frequency varying magnetic field within the interior space of induction coil 12 and thus within cavity 16, as indicated by the dashed line in FIG. 2 . The frequency of the high-frequency varying magnetic field may be in the range of 500 kHz (kilohertz) to 30 MHz (megahertz), particularly 5 MHz (megahertz) to 15 MHz (megahertz), and preferably 5 MHz (megahertz) to 10 MHz (megahertz). As described in further more detail below, the alternating magnetic field is used to induce at least one of heat-generating eddy currents or hysteresis losses within susceptor 22 of article 2 to vaporize aerosol-forming liquid 25 contained within article 2.

[0108] Next to the device 1, FIG. 1 also shows details of the aerosol-generating article 2. In this embodiment, the article 2 is a cartridge having a mushroom-type shape that can be coupled to the device 1. At its distal end, the article 2 comprises an elongated evaporation portion 29 configured to be inserted into the receiving cavity 16 of the device 1, as shown in FIGS. 2 and 3 . Within the evaporation portion 29, the article 2 comprises a susceptor 22 disposed within the article 2 such that the susceptor 22 is located within the interior space of the induction coil 13 when the evaporation portion 29 of the article 2 is inserted into the cavity 16. Therefore, the susceptor 22 may experience an alternating magnetic field generated by the induction coil 13 during operation of the heating arrangement 10 in order to heat up.

[0109] In this embodiment, the susceptor 22 is a flat sheet-like mesh made of inductively heatable ferromagnetic stainless steel. As a result, the susceptor 22 may also be viewed as a sheet-like mesh susceptor 22 capable of performing both the functions of drawing (transporting) and heating the aerosol-forming liquid 25. Because the material of the susceptor 22 at hand is both conductive and magnetic, the alternating electromagnetic field of the induction coil 13 can induce both heat-generating eddy currents and hysteresis losses in the susceptor material.

[0110] The susceptor mesh 22 is in fluid communication with the aerosol-forming liquid 25 contained in the reservoir 24 of the article 2 by a porous suction element 28. The porous suction element 28 is configured to directly contact the liquid 25 in the reservoir 24 and transport the liquid 25 to the mesh susceptor 22. Thus, the susceptor mesh 22 is continuously wetted. Upon inserting the article 2 into the cavity 16 (see FIGS. 2 and 3) and activating the heating arrangement 10, the mesh susceptor 22 is heated to a temperature sufficient to vaporize the aerosol-forming liquid 25 in contact with the mesh susceptor 22.

[0111] As can be further seen in particular in FIG. 1 , mesh susceptor 22 is disposed within airflow channel 26 that passes through article 2 along its central axis. Airflow channel 26 has an air inlet at the distal end of article 2 and an outlet at the proximal end of article 2. The outlet is formed by mouthpiece 21, through which a user can inhale. Thus, when a user inhales at mouthpiece 21 during use of the system, air is entrained into airflow channel 26 via the air inlet and passes along mesh susceptor 22. There, vaporized material of the aerosol-forming liquid is entrained in the airflow through airflow channel 26. Thereafter, while passing further downstream within airflow channel 26 toward mouthpiece 21, the airflow containing the vaporized material is cooled, such that it forms an aerosol that exits article 2 through the outlet in mouthpiece 21.

[0112] The aerosol generating device 1 according to this embodiment further comprises a puff detector 14 for detecting a puff taken by the user. The puff detector 14 is operatively connected to the power supply electronics such that detection of the generation of a puff by the puff detector 14 triggers the delivery of power to the induction coil 13 for generating the aerosol. To this extent, the aerosol generating device 1 according to this embodiment may be referred to as an on-demand smoke suction device. When the user stops taking a puff, the delivery of power to the induction coil is interrupted to avoid unnecessarily generating unused aerosol. That is, the induction heating arrangement is operated intermittently according to the user's request.

[0113] In a continuous operating mode, the susceptor will be permanently maintained at a temperature level sufficient to form a satisfactory amount of aerosol, but if the heating arrangement is operated intermittently, such as upon user request (on-demand puffing), achieving a sufficient temperature level within a short period of time can be a challenge.

[0114] To achieve higher heating efficiency, specifically, to achieve a sufficient temperature level within a shorter period of time, it has been found to be advantageous to adapt the geometry of the magnetic field within the interior space of the induction coil 13 in which the susceptor 22 is placed to the flat, sheet-like shape of the susceptor 22. Specifically, it has been found that by flattening the transverse cross-sectional shape of the induction coil 13, the radial distance between the induction coil 13 and the main surface of the flat susceptor 22 can be reduced. The reduced radial distance leads to an increase in the magnetic field strength at the susceptor location, which in turn causes an increase in heating efficiency. Therefore, for a given level of power passing through the induction coil, the level of heat generated in the susceptor increases, which, among other things, makes it possible to reach the desired temperature level within a shorter period of time. Accordingly, in this embodiment, the outer periphery of the support tube 32 has a non-circular, flat transverse cross-sectional shape (see dashed lines in FIG. 4 ) consisting of two opposing flat sections 32.1 connected by two opposing, at least partially curved sections 32.2. Since the induction coil 13 is wound around the outer periphery of the support tube 32, the cross-sectional shape of the induction coil 13 follows the non-circular flattened cross-sectional shape of the outer periphery of the support tube 32. That is, the cylindrical helical induction coil 13 also has a non-circular flattened cross-sectional shape (see the dotted line on the right side of Figure 5) consisting of two opposing flat sections 13.1 connected by two opposing at least partially curved sections 13.2.

[0115] In this embodiment, the non-circular flattened cross-sectional shape of the support tube 32 and induction coil 13 is elliptical, i.e., it is made up of two semicircles 13.2, 32.2 connected by parallel lines 13.1, 32.1 tangent to their end points, so that the induction coil 13 and support tube 17 have an elliptical cylindrical shape.

[0116] Due to the parallel oval and semicircular sections, the non-circular, flattened cross-sectional shape of the induction coil 13 and support tube 32 has a minor axis of symmetry and a major axis of symmetry. As indicated by the dash-dotted arrow for the induction coil 13 on the right side of FIG. 5 , the minor axis of symmetry extends between the two opposing flat sections 13.1 of the induction coil 13, while the major axis of symmetry extends between the two opposing curved sections 13.2 of the induction coil. Preferably, the ratio of the maximum distance along the major axis of symmetry between the two opposing at least partially curved sections 13.2, 32.2 to the maximum distance along the minor axis of symmetry between the two opposing flat sections 13.1, 32.1 is in the range of 1.2 to 3, particularly 1.5 to 2.5. These ratios are particularly advantageous for achieving a good match between the magnetic field geometry and the planar shape of the susceptor 22 to be heated.

[0117] To further improve heating efficiency, the induction heating arrangement 10 of this embodiment includes a flux concentrator 50 disposed around the induction coil 13 and configured to distort the alternating magnetic field of the induction heating arrangement 10 toward the interior space of the induction coil 13 during use. To this end, the flux concentrator 50 has a particular configuration including a sleeve portion 52 circumferentially surrounding the induction coil 13, as well as annular protruding portions 51 at each axial end of the sleeve portion 52 that protrude radially inward beyond the sleeve portion 51, whereby the induction coil 13 is axially disposed between the annular protruding portions 51, as can be particularly seen in Figures 1 and 2. Thus, as seen in a longitudinal cross-section through the flux concentrator 50 along the length axis of the induction coil 13 (see Figures 1 and 2), the flux concentrator 50 has a U- or C-shape, with the sleeve portion 52 being part of the base of the U- or C-shape and the annular protruding portions 51 being part of the arms or legs of the U- or C-shape. To this extent, it has been found that the density of the magnetic field at the susceptor 22 can be increased by distorting the magnetic field toward the interior space of the induction coil 13 using the flux concentrator 50 shaped as described above. Specifically, the annular protrusions 51 at each axial end of the sleeve portion 52, which protrude radially inward beyond the sleeve portion 52, result in a concentration or focusing of the magnetic field within the interior space of the induction coil 13. Therefore, the level of heat generated within the susceptor 22 for a given level of power passing through the induction coil 13 is increased compared to an induction coil having only a sleeve-shaped flux concentrator without a flux concentrator or without annular protrusions at each axial end. In addition, the flux concentrator 50 acts as a magnetic shield, capable of reducing the extent to which the magnetic field propagates beyond the induction coil 13. Therefore, the flux concentrator 50 can be useful for reducing undesired heating of other sensitive components of the system or sensitive items external to the apparatus 1.

[0118] While the annular protrusion 51 should extend radially inward beyond the outer periphery of the induction coil 13 to ensure sufficient concentration of the magnetic field, it may be sufficient if the annular protrusion 51 extends radially inward at most to the inner periphery of the induction coil 13, i.e., if the annular protrusion does not protrude radially inward beyond the inner periphery of the induction coil 13.

[0119] In this embodiment, the flux concentrator 50 is constructed from flux concentrator foil. More specifically, each annular protrusion 51 is made of flux concentrator foil spirally wound on the coil support 17 in multiple layers, extending radially outward beyond the outer periphery of the induction coil 13. Over the annular protrusion 51, a sleeve portion 52 is formed of several layers of the same flux concentrator foil material, enveloping the induction coil 13 and each annular protrusion 51. As an example, a flexible three-layer ferrite sheet, available from Laird Corporation under the trade name MHLL6060-300, having a ferrite layer sandwiched between an adhesive layer and a cover layer, can be used as the flux concentrator foil. MHLL6060-300 has a foil thickness of approximately 90 micrometers, a real permeability of approximately 130, and an imaginary permeability of approximately 5 at a frequency of 13.56 MHz. 1-3 each have a height dimension (radial) of 2 millimeters and a width dimension (axial) of 2 millimeters. Sleeve portion 52 has a thickness dimension (radial) of approximately 180 micrometers and a width dimension (axial) of 10 millimeters. Thus, using a foil material having a foil thickness of 90 micrometers requires approximately 22 wraps to form a 2 millimeter high annular protrusion portion 51 and approximately 2 wraps to form a 180 micrometer thick sleeve portion 52.

[0120] The sleeve portion 52 is radially separated from the induction coil 13 by a radial gap having a width (radial extension) in the range of 0.5 mm to 1.5 mm, specifically 0.8 mm to 1 mm. Advantageously, the radial gap may help to avoid heat loss from the induction coil to the sleeve portion, reducing losses at the induction coil and increasing losses at the heated susceptor 22, i.e., increasing the heating efficiency of the aerosol generation device 1. Similarly, each of the annular protruding portions 51 is axially separated from the induction coil 13 by an axial gap. The radial gap and / or the axial gap may be an empty gap or may be a gap at least partially filled with a filler material.

[0121] Like the support tube 32 and the induction coil 13, the flux concentrator 50 may also have a non-circular flattened cross-sectional shape that corresponds to the non-circular flattened cross-sectional shapes of the support tube 32 and the induction coil 13. Specifically, the cross-sectional shape of the flux concentrator 50 may be oval.

[0122] 6, the more distal annular protruding portion 51 includes a recess or feed-through opening 501 for passing a connection lead 60 for the induction coil. The recess or feed-through opening 501 can be cut into the annular protruding portion 51 after the flux concentrator foil has been rolled.

[0123] To further increase the heating efficiency, the outer periphery of the support tube 32 in this embodiment is provided with a spiral wire recess pattern 39 in which the coil wire is received, as shown in Figures 4 and 6. Advantageously, the wire recess pattern 39 allows for a further reduction in the radial distance between the induction coil 13 and the location of the susceptor within the interior space of the induction coil 13. As already mentioned above, the reduced radial distance leads to an increase in the magnetic field strength at the location of the susceptor, which in turn causes an increase in the heating efficiency.

[0124] The greater the recess depth of the wire recess pattern 39, the better the magnetic field strength at the location of the susceptor within the internal space of the induction coil 13. For example, if the coil wire has a circular cross section, the radial depth of the wire recess pattern 39 is preferably within a range of 0.2 to 0.8 times, specifically 0.3 to 0.5 times, the diameter of the coil wire. The radial distance between the induction coil 13 and the inner periphery of the coil support 17 may be 0.1 to 1 mm, specifically 0.2 to 0.5 mm, and preferably approximately 0.3 mm, as shown in FIG. 6. This ensures a particularly short radial distance between the induction coil 13 and the internal space of the support tube 32 in which the susceptor 22 is received. That is, the radial distance a between the inner periphery of the support tube 32 and the bottom of the recess pattern 39 is 0.1 to 1 mm, specifically 0.2 to 0.5 mm, and preferably approximately 0.3 mm.

[0125] 2 and 6, the outer periphery of the support tube 32 may further include a flux concentrator recess 38 for each of the annular protruding portions 51 of the flux concentrator 50, into which the radially inward end of each annular protruding portion 51 is received. This provides a secure support for the annular protruding portions 51, which helps prevent the flux concentrator 50 from being displaced, which could otherwise lead to an undesired change in the inductance of the induction coil 13 and an undesirable change in the magnetic field density within the interior space of the induction coil 13.

[0126] FIG. 7 shows further details of the power supply electronics that can be used in the induction heating arrangement 10, specifically the aerosol generating device shown in FIGS. 1-3. According to this embodiment, the induction heating arrangement 10 comprises a DC / AC inverter connected to the DC power supply 12 shown in FIG. 1. The DC / AC inverter includes a class E power amplifier, which in turn includes the following components: a transistor switch 111 comprising a field-effect transistor (FET), e.g., a metal-oxide semiconductor field-effect transistor (MOSFET), a transistor switch supply circuit represented by arrow 112 for supplying a switching signal (gate-source voltage) to the transistor switch 111, and an LC load network 113 comprising a shunt capacitor C1 and a series connection of a capacitor C2 and an inductor L2. Inductor L2 corresponds to the induction coil 13 shown in FIGS. 1-3 that is used to generate an alternating magnetic field in the cavity 16. In addition, a choke L1 is provided for supplying a DC supply voltage +V_DC from the DC power supply 12. 7, the ohmic resistance R, which represents the total equivalent resistance or resistive load 114 when the system is in use, i.e., when an item 2 is inserted into the cavity 16 of the device 1, is the sum of the ohmic resistance of the induction coil 13, marked L2, and the ohmic resistance of the susceptor 22. Alternatively, when no item is inserted into the cavity 16, the equivalent resistance or resistive load 114 corresponds only to the ohmic resistance of the induction coil 13.

[0127] FIG. 8 shows another embodiment of power supply electronics that can alternatively be used in the aerosol generating device shown in FIGS. 1-3 to provide a high-frequency oscillating current to the induction coil 13. The configuration shown in FIG. 8 corresponds to a class D amplifier configuration. Here, a DC power supply 12 is connected to two transistors 1210, 1212. Two switching elements 1220, 1222 are provided to switch the two transistors 1210, 1212 on and off. The switching elements 1220, 1222 are controlled at high frequency in a manner that ensures that one of the two transistors 1210, 1212 is off when the other is on. The induction coil 13 used to generate the alternating magnetic field for induction heating is again represented by L2, and the combined ohmic resistance of the induction coil 13 and susceptor 22 is represented by R. The values of C1 and C2 can be chosen to maximize the efficient dissipation of power within the susceptor element. Capacitor C1 is not required to configure the architecture as Class D and can therefore be omitted.

[0128] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like are understood to be modified in all instances by the term "about." Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A ± 5%. Within this context, the number A may be considered to include a numerical value that is within the typical standard error for measurement of the property that the number A modifies. In some instances, as used in the appended claims, the number A may deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. An induction heating module for use in an induction heating aerosol generator, - A cylindrical helical induction coil for generating an alternating magnetic field that enables induction heating of a susceptor within the internal space of the induction coil in order to heat an aerosol-forming substrate that is in thermal contact or thermal proximity with the susceptor, wherein the induction coil is formed by one or more turns of a coil wire having a circular cross-section, An induction heating module comprising: a coil support for supporting the induction coil having a support tube, wherein the induction coil is wound around the outer circumference of the support tube, the outer circumference of the support tube has a wire recess pattern for receiving the coil wire, the outer circumference of the support tube has two magnetic flux concentration recesses suitable for receiving at least each annular projection of a flux concentrator, the wire recess pattern is axially arranged between the two magnetic flux concentration recesses, and the outer circumference of the support tube has a non-circular, flattened cross-sectional shape comprising, specifically, two opposing flat sections connected by two opposing, at least partially curved sections, and the induction coil is wound around the outer circumference of the support tube, thereby the cross-sectional shape of the induction coil conforms to the non-circular, flattened cross-sectional shape of the outer circumference of the support tube.

2. The induction heating module according to claim 1, wherein the distance between adjacent recesses in the wire recess pattern is greater than the diameter of the coil wire.

3. The induction heating module according to claim 1, wherein the distance between adjacent recesses in the wire recess pattern is within the range of 1.1 to 1.4 times the diameter of the coil wire, specifically 1.2 to 1.3 times.

4. The induction heating module according to claim 1, wherein the induction coil comprises 3 to 6 turns, specifically 4 to 5 turns.

5. The induction heating module according to claim 1, wherein the coil wire has a diameter in the range of 0.8 mm to 1.5 mm, specifically 1 mm to 1.2 mm.

6. The induction heating module according to claim 1, wherein the wire recess pattern corresponds to the winding pattern of the induction coil.

7. The induction heating module according to claim 1, wherein the coil wire is one of a solid wire, a stranded wire, and a Litz wire.

8. The induction heating module according to claim 1, wherein the depth of the recesses in the radial wire recess pattern is in the range of 0.2 to 0.8 times the diameter of the coil wire, specifically 0.3 to 0.5 times, and / or the radial distance between the inner circumference of the support tube and the bottom of the recess pattern is in the range of 0.1 to 1 millimeter, specifically 0.2 to 0.5 millimeters, preferably about 0.3 millimeters, and / or the radial distance between the inner circumference of the induction coil and the inner circumference of the support tube is in the range of 0.1 to 1 millimeter, specifically 0.2 to 0.5 millimeters, preferably about 0.3 millimeters.

9. The induction heating module according to claim 1, wherein the coil support is provided with circumferential collars at each axial end of the support tube.

10. The induction module according to claim 9, wherein at least one of the collars is provided with a recess or feedthrough opening for a connecting lead through which the induction coil passes.

11. The induction module according to claim 1, wherein the induction coil is wound around the outer circumference of the support tube, so that the cross-sectional shape of the induction coil conforms to the non-circular, flattened cross-sectional shape of the outer circumference of the support tube.

12. The induction heating module according to claim 11, wherein the non-circular, flattened cross-sectional shape of the support tube is oval, and preferably the cross-sectional shape of the induction coil is oval.

13. The induction heating module according to claim 11 or 12, wherein each of the at least partially curved sections is substantially semicircular, substantially semi-elliptical, substantially semi-elliptical, or substantially parabolic.

14. An induction heating aerosol generator for use with an aerosol generating article, wherein the article comprises an aerosol-forming substrate that is heated by the interaction of a susceptor with an alternating magnetic field provided by the aerosol generator, and the generator comprises the induction heating module described in claim 1.

15. An aerosol generating system comprising an aerosol generating device according to claim 14, and an aerosol generating article for use with the aerosol generating device, wherein the article comprises an aerosol-forming substrate that is heated by the interaction of a susceptor and an alternating magnetic field provided by the aerosol generating device.

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