Induction heating device for use in induction-heated aerosol-generating device

Abstract

The invention relates to an induction heating device for use in an induction-heated aerosol-generating device, in which the heating device comprises a cylindrical-spiral induction coil for generating an alternating magnetic field allowing induction heating of a susceptor within an inner space of the induction coil, the susceptor is thermally heated so as to heat the aerosol-forming substrate in thermal contact with or in thermal proximity to the susceptor. The heating device includes a flux concentrator disposed around the induction coil and configured to distort an alternating magnetic field of the induction heating device towards an interior space of the induction coil during use. The flux concentrator includes a sleeve portion circumferentially surrounding the induction coil and annular protruding portions protruding radially inward beyond the sleeve portion at each axial end of the sleeve portion, wherein the induction coil is axially arranged between the annular protruding portions. The invention also relates to an induction heating module comprising such a heating device, and an aerosol-generating device and an aerosol-generating system.

Description

[0001] The present disclosure relates to an induction heating device for use in an induction heating aerosol generating device, and also relates to an induction heating module, an aerosol generating device and an aerosol generating system comprising such a heating device.

[0002] Aerosol generating devices and systems for generating inhalable aerosols by inductively heating an aerosol-forming substrate are generally known from the prior art. Such systems and devices may include an induction heating device, which includes an induction coil for generating an alternating magnetic field. The field is used to cause at least one of heat-generating eddy currents or hysteresis losses in a susceptor, which is arranged to be in thermal proximity or direct physical contact with an aerosol-forming substrate that can form an inhalable aerosol when heated. The susceptor and the substrate may be a part of an aerosol-generating article that can be received in the internal space of the induction coil. In particular, the substrate may be a liquid aerosol-forming substrate stored in a liquid reservoir of the article. The reservoir may be in fluid communication with a susceptor located in the evaporation portion of the article, in which the aerosol-forming liquid may evaporate by the 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 that is in thermal proximity or direct physical contact with the susceptor, wherein both the susceptor and the substrate are contained in the evaporation portion of the article. Alternatively, the susceptor may also be a part of the aerosol generating device.

[0003] In some articles, the susceptor may have a flat shape, such as a sheet-like shape, which provides a large surface-to-mass ratio. A large surface-to-mass ratio is beneficial for efficiently utilizing the heat generated by the susceptor and enhancing heat transfer from the susceptor to the aerosol-forming substrate.

[0004] During the user's experience, the induction heating device can be operated continuously or on demand (particularly in an intermittent mode, such as on a puff-by-puff basis). While in the continuous operation mode, the susceptor is permanently maintained at a temperature level sufficient to form a satisfactory amount of aerosol, if the heating system is operated intermittently, such as on demand by the user, achieving a sufficient temperature level within a short period of time may be a challenge.

[0005] It is therefore desirable to have an induction heating device, an aerosol generating device and an aerosol generating system for inductively heating an aerosol-forming substrate that have the advantages of prior art solutions while alleviating their limitations. In particular, it is desirable to have an induction heating device, an aerosol generating device and an aerosol generating system for inductively heating an aerosol-forming substrate that each allow a higher heating efficiency to be achieved, in particular to reach a sufficient temperature level in a shorter period of time.

[0006] According to the present invention, an induction heating device for use in an induction-heating aerosol generating device is provided, wherein the heating device comprises at least one cylindrical-helical induction coil, in particular a single cylindrical-helical induction coil, for generating an alternating magnetic field, thereby allowing inductive heating of a susceptor within an inner space of the induction coil, so as to heat an aerosol-forming substrate in thermal contact or thermal proximity with the susceptor. The heating device comprises a flux concentrator, which is arranged around the induction coil and is configured to distort the alternating magnetic field of the induction heating device towards the inner space of the induction coil during use. The flux concentrator comprises a sleeve portion circumferentially surrounding the induction coil, and further comprises an annular protrusion portion protruding radially inwardly beyond the sleeve portion at each axial end of the sleeve portion, so that the induction coil is axially arranged between the annular protrusion portions.

[0007] According to the present invention, it has been found that the heating efficiency of an induction heating device for a given operating power can be improved by increasing the density of the magnetic field within the inner space of the induction coil where the susceptor is to be placed during use. In particular, it has been found that the density of the magnetic field at the location of the susceptor can be increased by distorting the magnetic field towards the inner space of the induction coil using a flux concentrator shaped as described above. In particular, the annular protrusion portion protruding radially inwardly beyond the sleeve portion at each axial end of the sleeve portion causes a concentration or focusing of the magnetic field within the inner space of the induction coil. As a result, the level of heat generated in the susceptor for a given power level passing through the induction coil is increased compared to an induction coil without a flux concentrator or with only a sleeve-shaped flux concentrator without an annular protrusion portion at each axial end.

[0008] In addition to this, the flux concentrator acts as a magnetic shield, which can reduce the extent to which the magnetic field propagates beyond the induction coil. Thus, the flux concentrator can help reduce undesired heating of adjacent sensitive parts (e.g., a metal outer casing of an aerosol generating device with which the heating device is to be used). Likewise, the flux concentrator can help reduce undesired heating of adjacent sensitive items external to the device. Thus, by reducing undesired heating losses, the efficiency of the induction heating device can be further improved.

[0009] The efficiency of the induction heating device is further increased by the use of a cylindrical-helical induction coil, which advantageously allows a uniform alternating magnetic field to be generated.

[0010] As used herein, the term "flux concentrator" refers to a component with high relative magnetic permeability, which is used to concentrate and guide the magnetic field or magnetic field lines generated by the induction coil. As used herein, the term "high relative magnetic permeability" refers to a relative magnetic permeability of at least 50 or 100, in particular at least 1000, preferably at least 10000, even more preferably at least 50000, most preferably at least 80000. These example values ​​refer to the maximum value of the relative magnetic permeability for frequencies up to 50kHz and a temperature of 25 degrees Celsius. The term "relative magnetic permeability" refers to the ratio of the magnetic permeability of a material or medium (such as a flux concentrator) to the magnetic permeability μ_0 of free space, where μ_0 is 4π·10 -7 N.A -2 (4·Pi·10E-07 newtons per square ampere).

[0011] Preferably, the flux concentrator comprises or is made of one or more layers of flux concentrator foil. A flux concentrator comprising or is made of one or more layers of flux concentrator foil is more flexible than other flux concentrator constructions (e.g. solid ferrite bodies). Thus, foil-based flux concentrators provide improved shock absorbing properties and can therefore withstand higher excessive force shocks or vibrations without breaking. For example, compared to susceptors made of sintered ferrite powder, foil-based flux concentrators provide greatly improved resistance to shock loads such as those generated by accidental drops. In addition, foil-based flux concentrators allow for a more compact design of the heating device. Furthermore, foil-based flux concentrators also allow for compensation of manufacturing tolerances and fine-tuning of inductance compared to solid body flux concentrators. The flux concentrator foil can advantageously help to enhance the impedance stability of the induction coil over temperature. In general, the impedance of the induction coil is affected by the presence of the flux concentrator. When using a foil-based flux concentrator, the conductance of the induction heating device may vary less with temperature due to the smaller volume of the foil, especially compared to a larger solid body flux concentrator. As a result, the impedance may also vary less with temperature. Furthermore, foil-based flux concentrators are easy to manufacture.

[0012] According to a preferred arrangement of the flux concentrator, each of the annular protruding portions may be made of one or more layers of a flux concentrator foil, wherein the one or more layers of the annular protruding portions extend in a radially outward direction at least to the outer circumference of the induction coil, preferably beyond the outer circumference of the induction coil. On top of the annular protruding portions, a sleeve portion may be made of one or more layers of a flux concentrator foil surrounding the induction coil and each of the annular protruding portions. That is, the flux concentrator may be realized by providing, in a first step, one or more turns of a flux concentrator foil at each axial end of the induction coil such that the induction coil is axially sandwiched between the two windings forming the annular protruding portions, and subsequently in a second step, winding one or more layers of a flux concentrator foil on top of the annular protruding portions and the induction coil to form the sleeve portion.

[0013] According to an alternative arrangement 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 protrusion portions may be made of one or more layers of flux concentrator foil to end flush with the outer circumference of the sleeve portion in the radial direction. That is, the one or more layers of flux concentrator foil forming the sleeve portion are sandwiched between two windings of the flux concentrator coil, forming the annular protrusion portion.

[0014] Generally speaking, the flux concentrator foil used to form the annular protruding portion may be the same as the flux concentrator foil used to form the sleeve portion. However, it is also possible that the flux concentrator foil used to form the annular protruding portion is different from the flux concentrator foil used to form the sleeve portion.

[0015] As used herein, the term "foil" refers to a thin sheet of material having a thickness much smaller than the dimension in any direction perpendicular to the thickness. As used herein, the term "thickness" refers to the dimension of the foil perpendicular to the major surfaces of the foil.

[0016] The flux concentrator foil may have a foil thickness in the range between 50 and 250 microns, in particular between 80 and 150 microns. Such values ​​of thickness allow easy winding of the foil while still ensuring that the flux concentrator has sufficient mechanical stability.

[0017] Preferably, the flux concentrator foil is a multilayer flux concentrator foil comprising at least one ferrite layer sandwiched between an adhesive layer and a cover layer.

[0018] The adhesive layer advantageously facilitates the wrapping and securing of one or more layers of the flux concentrator foil, forming the sleeve portion and the annular protruding portion.

[0019] The cover layer may be or may include a polymer film. The polymer film may be selected from polyester, polyimide, polyol or a combination thereof. For example, the cover layer may be a PET-based (polyethylene terephthalate-based) cover layer.

[0020] At least one, preferably both, of the adhesive layer and the cover layer may be an edge layer, ie the outermost layer, of the multilayer flux concentrator foil.

[0021] For example, the flux concentrator foil may be a flexible ferrite sheet available from Laild Corporation under the product name MHLL6060-300 or MULL6060-300. MHLL6060-300 has a real permeability of about 130 and a fictive permeability of about 5 at a frequency of 13.56 MHz. MULL6060-300 has a real permeability of about 150 and a fictive permeability of about 5 at a frequency of 13.56 MHz.

[0022] The sleeve portion may be spaced apart from the induction coil in the radial direction by a radial gap. The radial gap may have a width (radial extension) in the range between 0.5 mm and 1.5 mm, in particular between 0.8 mm and 1 mm. Advantageously, the radial gap may help reduce losses in the induction coil and increase losses in the susceptor to be heated, i.e. increase the heating efficiency of the aerosol generating device.

[0023] Likewise, at least one of the annular projections, preferably each of the annular projections, may be spaced apart from the induction coil by an axial gap in the axial direction.

[0024] The radial gap and / or the axial gap may be an air gap or a gap at least partially filled with a filling material, such as a polyimide, for example poly(4,4'-oxydiphenylene-pyromellitimide), also known as or any other suitable dielectric material.

[0025] In order to ensure that a sufficiently concentrated magnetic field enters the inner space of the induction coil, the annular protrusion preferably extends radially inwardly beyond the outer circumference of the induction coil. Thus, the induction coil is at least partially sandwiched between the annular protrusions.

[0026] Conversely, it has been found that concentration of the magnetic field into the interior space of the induction coil is sufficient if the annular protrusion extends radially inwards at most to the inner circumference of the induction coil, ie if the annular protrusion does not protrude radially inwards beyond the inner circumference of the induction coil.

[0027] The width dimension of each of the annular protrusions in the axial direction may be in the range between 1.5 mm and 2.5 mm, in particular between 1.8 mm and 2.2 mm. Width dimensions in these ranges have proven to be advantageous for sufficiently distorting the magnetic field into the inner space of the induction coil while still achieving a compact design of the induction heating device. The latter is particularly important in the case where the induction heating device is to be implemented in a handheld / portable aerosol generating device.

[0028] Likewise, the height dimension of each of the annular protruding portions in the radial direction may range between 1.5 mm and 2.5 mm, in particular between 1.8 mm and 2.2 mm. Advantageously, the height dimension is a function of the thickness of the sleeve and the cross section of the wire forming the coil.

[0029] The thickness dimension of the sleeve portion in the radial direction may be in the range between 100 micrometers and 500 micrometers, in particular between 150 micrometers and 250 micrometers. In this regard, it has been found that the sleeve portion may be quite thin in order to still sufficiently concentrate and shield the magnetic field. A thin sleeve portion also proves to be advantageous in terms of a compact design of the induction heating device.

[0030] The width dimension of each sleeve portion in the axial direction may be in the range between 7 mm and 12 mm, in particular between 9 mm and 11 mm.

[0031] In general, the flux concentrator may have any cross-sectional shape. Preferably, the shape of the flux concentrator matches the shape of the cylindrical-helical induction coil. Thus, the sleeve portion and the annular protrusion portion may each have a cylindrical shape.

[0032] As seen in a longitudinal section through the flux concentrator along the length axis of the induction coil, the flux concentrator may have a U-shape or C-shape, wherein the sleeve portion is part of the base of the U-shape or C-shape and the annular protrusion portion is part of the arm or leg of the U-shape or C-shape.

[0033] At least one of the annular protruding portions, preferably the more distal annular protruding portion, may comprise a recess or a feed-through opening for passing a connecting lead for the induction coil. In case the flux concentrator is formed by winding a flux concentrator foil, the recess or the feed-through opening may be cut into the annular protruding portion after winding the flux concentrator foil.

[0034] Preferably, the inner space of the induction coil is configured to removably receive at least a portion of the aerosol-generating article, in particular the evaporation portion of the aerosol-generating article. The evaporation portion of the article may include a susceptor, in particular a flat susceptor, more particularly a sheet-like susceptor, for heating the aerosol-forming substrate contained in the article by interaction of the susceptor with the alternating magnetic field of the induction coil. That is, the susceptor to be inductively heated by the induction coil may be part of the aerosol-generating article. Alternatively, the susceptor to be inductively heated by the induction coil may be part of an aerosol-generating device, the induction heating device being configured to be used in / with the aerosol-generating device.

[0035] In general, a cylindrical-spiral induction coil can be formed by one or more turns of a coil wire. For example, the induction coil comprises 3 to 6 turns, in particular 4 to 5 turns. The number of turns does not necessarily need to be an integer. It can also be any number between two integers.

[0036] Preferably, the coil wire may have a circular cross-section.

[0037] The coil wire may be one of a solid wire, a stranded wire, and a Litz wire.

[0038] When the induction coil is driven by AC current, the current through the coil wire flows only close to 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.

[0039] In order to achieve a compact coil design with a sufficiently large number of turns per unit length, it can be advantageous if the diameter of the coil wire is in the range between 0.8 mm and 1.5 mm, in particular between 1 mm and 1.2 mm.

[0040] Preferably, the induction coil has an axial length extension which is similar to the axial length extension of the susceptor measured in the same direction when received in the inner space of the induction coil. The axial length of the induction coil may be in the range between 4 mm and 12 mm, in particular between 5 mm and 8 mm.

[0041] Preferably, there is a gap between adjacent turns of the induction coil. That is, as seen in a longitudinal cross section of the induction coil, the pitch of the spiral induction coil may be greater than the extension of the cross section of the coil wire in the axial direction. In particular, in the case where the coil wire has a circular cross section, the pitch of the spiral induction coil may be greater than the diameter of the coil wire. Therefore, the coil wires of adjacent turns do not touch each other. This allows the use of coil wires without wire insulation. However, the coil wire may be an insulated coil wire. For example, the coil wire may be a coated copper wire, such as an enamel-coated copper wire. In addition, the gap between adjacent turns of the induction coil is used for better heat dissipation and thus makes the resistive power loss in the coil winding smaller. The gap between adjacent turns also helps to reduce undesirable ringing effects / crossover effects. As seen in a longitudinal cross section of the induction coil, the (center-to-center) distance between adjacent parts of the coil wire of adjacent turns may be in the range of between 1.1 and 1.4 times, in particular between 1.2 and 1.3 times, of the extension of the cross section of the coil wire in the axial direction. In particular, in the case of a coil wire having a circular cross section, the (center-to-center) distance between adjacent portions of the coil wire of adjacent turns is in the range between 1.1 and 1.4 times, in particular between 1.2 and 1.3 times, the diameter of the coil wire. These ranges have proven to provide sufficiently large distances (which still allow a compact coil design), i.e. a sufficiently large number of turns per length unit.

[0042] In case the induction heating device is intended for heating a flat susceptor, in particular a sheet-like susceptor, it may be advantageous to adapt the geometry of the magnetic field within the inner space of the induction coil where the susceptor is to be placed to the flat shape of the susceptor. Thus, the cylindrical-spiral induction coil may have a non-circular flattened cross-sectional shape comprising, in particular consisting of, two opposite flat sections connected by two opposite at least partially curved sections. Advantageously, by flattening the cross-sectional shape of the induction coil, the radial distance between the induction coil and the main surface of the flat susceptor may be reduced, provided that the susceptor is placed so that the main surface is aligned with the two opposite flat sections of the cross-sectional shape of the outer circumference of the support tube. The reduced radial distance results in an increase in the magnetic field strength at the location of the susceptor, which in turn results in an increase in the heating efficiency. Thus, for a given power level passing through the induction coil, the level of heat generated in the susceptor is increased, which in particular allows to reach the desired temperature level in a shorter period of time.

[0043] Preferably, the non-circular flattened cross-sectional shape of the induction coil comprises a short symmetry axis and a long symmetry axis. The short symmetry axis may extend between two opposing flat sections of the induction coil. Conversely, the long symmetry axis may extend between two opposing at least partially curved sections of the induction coil.

[0044] Preferably, the ratio of the maximum distance between two opposing at least partially curved sections along the long symmetry axis to the maximum distance between two opposing flat sections along the short symmetry axis is in the range between 1.2 and 3, in particular between 1.5 and 2.5. These ratios are particularly advantageous with regard to a suitable match between the geometry of the magnetic field and the flat shape of the susceptor to be heated.

[0045] In order to arrange the induction coil as close as possible to the inner space of the induction coil where the susceptor is to be placed, the maximum distance along the short symmetry axis between two opposing flat sections may be in the range between 4 mm and 7 mm, in particular between 5 mm and 6 mm. Likewise, the maximum distance along the long symmetry axis between two opposing at least partially curved sections may be in the range between 7 mm and 10 mm, in particular between 8 mm and 9 mm.

[0046] Preferably, the two opposing flat sections are substantially parallel to each other. The parallel configuration is particularly helpful for matching the magnetic field geometry to a susceptor having a sheet-like shape. In particular, each of the two opposing flat sections is a substantially straight line.

[0047] In particular, the non-circular flattened cross-sectional shape of the induction coil is oblong. As used herein, the term "oblong" defines a shape consisting of two semicircles connected by parallel lines tangent to their endpoints. Thus, the induction coil may have an oblong-cylindrical shape.

[0048] Similar to the induction coil, the flux concentrator may have a non-circular flattened cross-sectional shape corresponding to the non-circular flattened cross-sectional shape of the induction coil, i.e. a non-circular flattened cross-sectional shape comprising, in particular consisting 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 oblong.

[0049] In addition to the induction coil and the flux concentrator, the induction heating device may include an alternating current (AC) generator. The AC generator may be powered by a power source, in particular a DC power source. The power source may be part of an aerosol generating device in which the induction heating device is configured to be used. The AC generator is operatively coupled to at least one induction coil. In particular, 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 will pass through the induction coil for generating a varying magnetic field. The AC current may be continuously supplied to the induction coil after activation of the system, or may be intermittently supplied, for example on a puff-by-puff basis.

[0050] Preferably, the induction heating device comprises a DC / AC converter connectable to a DC power source, which DC / AC converter may be part of an aerosol generating device in which the induction heating device is configured for use.

[0051] The DC / AC converter may include an LC network. For example, the DC / AC converter may include a power amplifier, the power amplifier being in particular a switching power amplifier, more in particular 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. In particular, the DC / AC converter may include at least one transistor switch (in particular a single transistor switch), at least one transistor switch drive circuit and at least one LC network. The LC network may include a series connection of a capacitor and an inductor, wherein the inductor is a cylindrical-spiral induction coil of an induction heating device according to the present invention, i.e., an induction coil for generating an alternating magnetic field for heating an article to be received in the inner space of the induction coil. The LC network may also 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 supply.

[0052] The induction heating device is preferably configured to generate a high-frequency changing magnetic field. As mentioned herein, the high-frequency changing magnetic field can have a frequency in the range between 500kHz (kilohertz) and 30MHz (megahertz), in particular between 5MHz (megahertz) and 15MHz (megahertz), preferably between 5MHz (megahertz) and 10MHz (megahertz).

[0053] The induction heating device comprising the induction coil and the flux concentrator may be part of an induction module configured to be used in, in particular arranged in, an induction heated aerosol generating device.

[0054] In this respect, the invention also relates to an induction heating module for use in an induction heated aerosol generating device, wherein the induction heating module comprises an induction heating device according to the invention and as described herein. The induction heating module may for example be arranged in a device housing of the induction heated aerosol generating device.

[0055] Preferably, the induction heating module further comprises a coil support, on which the induction coil and the flux concentrator are supported.

[0056] The coil support may comprise a support tube, in particular a cylindrical support tube, wherein the induction coil is arranged around the circumference of the support tube.

[0057] The interior space of the support tube may form a receiving cavity for removably receiving at least a portion of the aerosol-generating article, in particular at least a vaporization portion of the aerosol-generating article. The vaporization portion may include a susceptor for heating the aerosol-forming substrate contained in the article by interaction of the susceptor with the alternating magnetic field of the induction coil.

[0058] In order to provide lateral confinement of the coil windings in the axial direction, the coil support may comprise a circumferential collar at each axial end of the support tube.

[0059] At least one of the collars may include a recess or a feed-through opening for passing connecting leads for the induction coil.

[0060] In case the induction heating device is intended for heating a flat susceptor, in particular a sheet-like susceptor, it may be advantageous that, similar to the induction coil, the outer circumference of the support tube also has a non-circular flattened cross-sectional shape, said non-circular flattened cross-sectional shape comprising, in particular consisting of, two opposite flat sections connected by two opposite at least partially curved sections. That is, the outer portion (outer portion) of the support tube along its outer circumference may comprise, in particular may consist of, two opposite flat outer portions connected by two opposite at least partially curved outer portions. In this configuration, the induction coil may be wound around the outer circumference of the support tube such that the cross-sectional shape of the induction coil follows the non-circular flattened cross-sectional shape of the outer circumference of the support tube. As already described further above with respect to the heating device, flattening the cross-sectional shape of the induction coil leads to an increase in the magnetic field strength at the location of the susceptor, which in turn leads to an increase in the heating efficiency.

[0061] Preferably, the non-circular flattened cross-sectional shape of the support tube is oblong, in particular in case the cross-sectional shape of the induction coil is also oblong. As used herein, the term "oblong" defines a shape consisting of two semicircles connected by parallel lines tangential to their end points. Thus, the support tube and the induction coil may have an oblong-cylindrical shape, i.e. a flattened cylindrical shape having two opposing planar side wall portions parallel to each other and having two opposing side hemispherical wall portions between the two opposing planar side wall portions.

[0062] Likewise, the cross-sectional shape of the flux concentrator may be oblong.

[0063] In the case where the outer circumference of the support tube has a non-circular flattened cross-sectional shape as described above, each of the above-mentioned collars (if present) may also have a non-circular flattened cross-sectional shape corresponding to the non-circular flattened cross-sectional shape of the outer circumference of the support tube. In particular, each collar may have an oblong cross-sectional shape.

[0064] In order to stabilize the coil winding, the outer periphery of the support tube may include a wire recess pattern in which the coil wire is received. The wire recess pattern is preferably selected so that it corresponds to the desired winding pattern of the induction coil. Since the induction coil is a cylindrical-spiral induction coil, the wire recess pattern is preferably also a spiral wire recess pattern.

[0065] In addition, the wire recess pattern allows to further reduce the radial distance between the induction coil and the susceptor location within the inner space of the induction coil. As already described above, the reduced radial distance leads to an increase in the magnetic field strength at the susceptor location, which in turn leads to an increase in the heating efficiency. Thus, for a given power level passing through the induction coil, the level of heat generated in the susceptor is increased, which in addition to the non-circular flattened cross-sectional shape of the outer circumference of the support tube further serves to reach the desired temperature level within a shorter period of time. The greater the depth of the recesses of the wire recess pattern, the better the magnetic field strength at the susceptor location within the inner space of the induction coil. For example, in case the coil wire has a circular cross section, the depth of the recesses of the wire recess pattern in the radial direction is preferably in the range between 0.2 and 0.8 times, in particular between 0.3 and 0.5 times, the diameter of the coil wire.

[0066] The outer periphery of the support tube may further include a flux concentrator recess for each of the annular protrusions of the flux concentrator, in which the radially inward end of the corresponding annular protrusion is received. Thereby, the annular protrusion is securely supported, which helps prevent the flux concentrator from being displaced. Otherwise, the displacement may cause an undesirable change in the inductance of the induction coil and an undesirable change in the magnetic field density in the inner space of the induction coil.

[0067] With regard to simple and cheap manufacturing, the coil support may comprise or may be made of plastic. In case the induction heating module has to comply with certain regulatory requirements, the coil support may comprise or may be made of bisphenol A-free plastic.

[0068] Further features and advantages of the induction heating module, in particular the induction coil and the flux concentrator, have been described in relation to the induction heating device of the present invention and are equally applicable.

[0069] The present invention also relates to an induction heating aerosol generating device for use with an aerosol generating article, wherein the article comprises an aerosol-forming substrate to be heated by the interaction of a susceptor with an alternating magnetic field provided by the aerosol generating device. The device comprises an induction heating device according to the invention and as described herein, or an induction heating module according to the invention and as described herein.

[0070] 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, the at least one aerosol generating article comprising an aerosol-forming substrate, in particular an aerosol-forming liquid, and a susceptor, so as to generate an aerosol by inductively heating the substrate via the interaction of the susceptor with an alternating magnetic field provided by the device. Preferably, the aerosol generating device is a suction device for generating an aerosol that can be directly inhaled by a user through the user's mouth. In particular, the aerosol generating device is a handheld aerosol generating device.

[0071] The aerosol generating device may comprise a device housing in which the induction heating device or the induction heating module according to the invention is located or arranged.

[0072] The aerosol generating device, in particular the device housing, may comprise an insertion opening allowing access to the interior space of the induction coil or the interior space of the support tube of the induction heating module in order to enable insertion of an aerosol generating article therein.

[0073] The aerosol generating device may further comprise a receiving chamber for removably receiving at least a portion, in particular a vaporized portion, of the aerosol generating article. The receiving chamber may be at least partially located within the inner space of the induction coil or the inner space of the support tube of the induction heating module. In particular, the receiving chamber may be at least partially formed by the inner space of the induction coil or the support tube of the induction heating module, in particular by the inner space of the support tube of the induction heating module. When the aerosol generating article is received in the receiving chamber, the induction coil may be arranged so as to surround at least a portion of the receiving chamber, in particular so as to surround at least the vaporized portion of the aerosol generating article.

[0074] The aerosol generating device may further comprise a puff detector, such as a microphone or a pressure sensor, for detecting the user's puff, i.e. the start of the user experience when the user starts to puff on the device. The puff detector may be operatively connected to the heating device and / or the controller. Thus, the occurrence of a puff detected by means of the puff detector may trigger the delivery of power to the induction coil for generating an aerosol. That is, the heating device and / or the controller may be configured to start the operation of the heating device, in particular the generation of an alternating magnetic field, in response to the puff detector detecting the occurrence of a puff by the user.

[0075] The aerosol generating device may further comprise a controller configured to control the operation of the device. In particular, the controller may be configured to control the operation of the induction heating device, preferably in a closed-loop configuration, for controlling the heating of the aerosol-forming substrate to a predetermined operating temperature. Depending on at least one of the type of aerosol-forming substrate to be 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 between 180 degrees Celsius and 370 degrees Celsius, in particular between 180 degrees Celsius and 240 degrees Celsius or between 280 degrees Celsius and 370 degrees Celsius.

[0076] The controller may include a microprocessor, such as a programmable microprocessor, a microcontroller or an application specific integrated chip (ASIC), or other electronic circuitry capable of providing control. The controller may include further electronic components, such as at least part of the induction heating device, in particular parts of an alternating current (AC) generator, such as a DC / AC inverter and / or parts of a power amplifier. In particular, the induction heating device may be at least partly part of the controller.

[0077] The aerosol generating device may comprise a power supply, in particular a DC power supply, configured to provide a DC supply voltage and a DC supply current to the induction heating device. Preferably, the power supply is a battery, such as a lithium iron phosphate battery. The power supply may have sufficient capacity to allow continuous generation of aerosol for a period of about six minutes or a period of a multiple of six minutes. Likewise, the power supply may have sufficient capacity to allow a predetermined number of puffs or discontinuous activation of the induction heating device.

[0078] The susceptor for heating 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 with which the device is configured for use. In particular, the susceptor may be arranged in 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 for removably receiving at least the evaporation portion of the aerosol generating article.

[0079] Alternatively, the susceptor for heating 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. That is, the aerosol generating device may include a susceptor for heating the aerosol-forming substrate. Further features and advantages of the aerosol generating device have been described in relation to the induction heating device and induction heating module of the present invention and are equally applicable.

[0080] The present invention also relates to an aerosol generating system comprising an aerosol generating device according to the present invention and as described herein and an aerosol generating article for use with the aerosol generating device. The article comprises an aerosol forming substrate to be heated by the interaction of a susceptor with an alternating magnetic field provided by the aerosol generating device.

[0081] 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 invention and as described herein. In the system, the article and the device cooperate to generate an inhalable aerosol.

[0082] As used herein, the term "aerosol-generating article" refers to an article comprising at least one aerosol-forming substrate which releases volatile compounds that can form an aerosol when heated. Preferably, the aerosol-generating article is a heated aerosol-generating article. That is, the aerosol-generating article comprises at least one aerosol-forming substrate which is intended to be heated rather than burned in order to release volatile compounds that can form an aerosol. The aerosol-generating article may be a consumable, in particular a consumable that is to be 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.

[0083] As used herein, the term "aerosol-forming substrate" generally refers to a substrate formed by or including an aerosol-forming material, which can release volatile compounds when heated to generate an aerosol. The aerosol-forming substrate is intended to be heated rather than burned to release aerosol-forming volatile compounds. The aerosol-forming substrate can 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 can contain both solid aerosol-forming materials or components and liquid aerosol-forming materials or components. The aerosol-forming substrate, particularly the aerosol-forming liquid, can include a tobacco-containing material comprising volatile tobacco flavor compounds, which are released from the substrate when heated. Alternatively or in addition, the aerosol-forming substrate, particularly the aerosol-forming liquid, can include non-tobacco materials. The aerosol-forming substrate, particularly the aerosol-forming liquid, can also include an aerosol-forming agent. The example of suitable aerosol forming agent is glycerol and propylene glycol. Aerosol forming substrate, particularly aerosol forming liquid can also contain other additives and ingredients, such as nicotine or spices. In particular, aerosol forming liquid can include water, solvent, ethanol, plant extract and natural or artificial flavoring agent. Aerosol forming liquid can be water-based aerosol forming liquid or oil-based aerosol forming liquid. Aerosol forming substrate can also be a pasty material, including a porous material pouch of aerosol forming substrate, or for example loose tobacco mixed with a gelling agent or a tackifier, which can include common aerosol forming agents such as glycerol, and be compressed or molded into a rod.

[0084] As described above in relation to an aerosol-generating device according to the invention, the susceptor for heating the aerosol-forming substrate may be part of the aerosol-generating device or aerosol-generating article. That is, the aerosol-generating device or aerosol-generating article comprises a susceptor for heating the aerosol-forming substrate.

[0085] In the latter case, the aerosol generating article may include a evaporation portion, wherein the susceptor for heating the aerosol-forming substrate is arranged in the evaporation region. In this configuration, the interior space of the induction coil and / or the interior space of the support tube of the induction heating module of the aerosol generating device is preferably configured for removably receiving at least the evaporation portion of the aerosol generating article.

[0086] As used herein, the term "susceptor" refers to an element capable of converting electromagnetic energy into heat when subjected to a changing magnetic field. This may be the result of at least one of hysteresis losses or eddy currents induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material. In a ferromagnetic or ferrimagnetic susceptor, hysteresis losses occur due to the transformation of magnetic domains within the susceptor material under the influence of a changing magnetic field. If the susceptor is electrically conductive, eddy currents may be induced. In the case of an electrically conductive ferromagnetic or ferrimagnetic susceptor, heat may be generated due to both eddy currents and hysteresis losses.

[0087] Thus, 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 made from 400 series stainless steel, such as 410 grade or 420 grade or 430 grade stainless steel.

[0088] The susceptor may comprise various geometric configurations depending, inter alia, on the type of aerosol-forming substrate.

[0089] The susceptor may comprise or be a susceptor pin, a susceptor rod, a susceptor blade, a susceptor strip or a susceptor plate. Preferably, the susceptor is a flat susceptor, more particularly a sheet-like susceptor. Likewise, the susceptor may comprise or be a susceptor sleeve, a susceptor cup, a cylindrical susceptor or a tubular susceptor.

[0090] In particular, where the substrate is a liquid (i.e., an aerosol-forming liquid), the susceptor may include or may be a filamentous susceptor, a mesh susceptor, a wick susceptor. In any of these configurations, the susceptor is advantageously capable of performing two functions: wicking (transporting) and heating the aerosol-forming liquid. Thus, in any of the aforementioned configurations, the susceptor may be considered a liquid transport susceptor.

[0091] Where 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.

[0092] Further features and advantages of the aerosol generating system have been described in relation to the induction heating device, the induction heating module and the aerosol generating device of the present invention and are equally applicable.

[0093] As used herein, the terms "radial" and "axial" refer to the cylindrical geometry of a cylindrical induction coil.

[0094] The invention is defined in the claims. However, a non-exhaustive list of non-limiting examples is provided below. Any one or more features of these examples may be combined with any one or more features of another example, embodiment or aspect described herein.

[0095] Example Ex1: An induction heating device used in an induction heating aerosol generating device, the heating device comprising:

[0096] a single cylindrical-helical induction coil for generating an alternating magnetic field allowing inductive heating of a susceptor within an interior space of the induction coil so as to heat an aerosol-forming substrate in thermal contact or proximity with the susceptor;

[0097] - a flux concentrator arranged around the induction coil and configured to distort the alternating magnetic field of the induction heating device towards the inner space of the induction coil during use, wherein the flux concentrator comprises a sleeve portion circumferentially surrounding the induction coil and an annular protrusion portion protruding radially inwardly beyond the sleeve portion at each axial end of the sleeve portion, wherein the induction coil is axially arranged between the annular protrusion portions.

[0098] Example Ex1a: An induction heating device according to Example Ex1, wherein the internal space of the induction coil is configured to removably receive at least a portion of an aerosol-generating article, in particular a evaporation portion, wherein the evaporation portion of the article preferably includes a susceptor, in particular a flat susceptor, more particularly a sheet-shaped susceptor, for heating the aerosol-forming substrate contained in the article by interaction between the susceptor and the alternating magnetic field of the induction coil.

[0099] Example Ex2: The induction heating device according to any of Example Ex1 or Example Ex1a, wherein the flux concentrator comprises or is made of one or more layers of flux concentrator foil.

[0100] Example Ex3: An induction heating device according to any one of Examples Ex1 to Ex2, wherein each of the annular protrusions is made of one or more layers of flux concentrator foil, the one or more layers of the annular protrusions extending in a radially outward direction at least to the outer circumference of the induction coil, preferably extending beyond the outer circumference of the induction coil, and wherein the sleeve portion is made of one or more layers of flux concentrator foil surrounding the induction coil and each of the annular protrusions.

[0101] Example Ex4: An induction heating device according to any one of Examples Ex1 to Ex2, wherein the sleeve portion is made of one or more layers of a flux concentrator foil surrounding the induction coil, and wherein each of the annular protrusion portions is made of one or more layers of a flux concentrator foil to end flush with the outer circumference of the sleeve portion in a radial direction.

[0102] Example Ex5: The induction heating device according to any of Examples Ex2 to Ex4, wherein the flux concentrator foil has a foil thickness in the range between 50 and 250 micrometers, in particular between 80 and 150 micrometers.

[0103] Example Ex6: The induction heating device according to any one of Examples Ex2 to Ex5, wherein the flux concentrator foil is a multilayer flux concentrator foil comprising at least one ferrite layer sandwiched between an adhesive layer and a cover layer.

[0104] Example Ex7: The induction heating device according to any one of the preceding examples, wherein the sleeve portion is spaced apart from the induction coil by a radial gap in the radial direction.

[0105] Example Ex8: The induction heating device according to example Ex7, wherein the radial gap has a width in a range between 0.5 mm and 1.5 mm, in particular between 0.8 mm and 1 mm.

[0106] Example Ex9: The induction heating device according to any one of the preceding examples, wherein each of the annular protruding portions is spaced apart from the induction coil by an axial gap in the axial direction.

[0107] Example Ex10: The induction heating device according to any one of the preceding examples, wherein the annular protrusion portion extends radially inwardly beyond the outer circumference of the induction coil.

[0108] Example Ex11: The induction heating device according to any one of the preceding examples, wherein the annular protrusion portion extends radially inward at most to the inner periphery of the induction coil.

[0109] Example Ex12: The induction heating device according to any one of the preceding examples, wherein the width dimension of each of the annular protruding portions in the axial direction is in the range between 1.5 mm and 2.5 mm, in particular between 1.8 mm and 2.2 mm.

[0110] Example Ex13: The induction heating device according to any one of the preceding examples, wherein the height dimension of each of the annular protruding portions in the radial direction is in the range between 1.5 mm and 2.5 mm, in particular between 1.8 mm and 2.2 mm.

[0111] Example Ex14: The induction heating device according to any one of the preceding examples, wherein a thickness dimension of the sleeve portion in the radial direction is in a range between 100 micrometers and 500 micrometers, in particular between 150 micrometers and 250 micrometers.

[0112] Example Ex15: The induction heating device according to any one of the preceding examples, wherein the sleeve portion and the annular protrusion portion each have a cylindrical shape.

[0113] Example Ex16: An induction heating module used in an induction heating aerosol generating device, the induction heating module comprising the induction heating device according to any one of the preceding examples.

[0114] Example Ex17: The induction heating module according to Example Ex16, further comprising a coil support, the induction coil and the flux concentrator being supported on the coil support.

[0115] Example Ex18: The induction heating module according to any one of Example Ex16 or Example Ex17, wherein the coil support comprises a support tube, wherein the induction coil is arranged around the circumference of the support tube.

[0116] Example Ex19: The induction heating module according to Example Ex18, wherein the interior space of the support tube forms a receiving cavity for removably receiving at least a portion of the aerosol-generating article.

[0117] Example Ex20: An induction heating module according to any one of Example Ex18 or Example Ex19, wherein the outer periphery of the support tube includes a flux concentrator recess for each of the annular protrusions of the flux concentrator, and the radially inward end of the corresponding annular protrusion is received in the flux concentrator recess.

[0118] Example Ex21: An induction heating aerosol generating device for use with an aerosol generating article, the article comprising an aerosol-forming substrate to be heated by the interaction of a receptor with an alternating magnetic field provided by the aerosol generating device, wherein the device comprises an induction heating device according to any one of Examples Ex1 to Ex15 or an induction heating module according to any one of Examples Ex16 to Ex20.

[0119] Example Ex22: An induction heating aerosol generating device according to Example Ex21, wherein the device further comprises a susceptor for heating the aerosol-forming substrate.

[0120] Example Ex23: An aerosol generating system, comprising an aerosol generating device according to Example Ex21 or Ex22 and an aerosol generating article for use with the aerosol generating device, the article comprising an aerosol-forming substrate to be heated by the interaction of a receptor with an alternating magnetic field provided by the aerosol generating device.

[0121] Example Ex24: An aerosol generating system according to example Ex23, wherein the aerosol generating device or the aerosol generating article comprises a susceptor for heating the aerosol-forming substrate.

[0122] Example Ex25: An aerosol generating system according to any one of examples Ex23 or Ex24, wherein the article comprises a evaporation portion, wherein the susceptor for heating the aerosol-forming substrate is arranged in the evaporation zone.

[0123] Example Ex26: An aerosol generating system according to Example Ex25, wherein the interior space of the induction coil and / or the interior space of the support tube of the induction heating module is configured to removably receive at least a vaporized portion of the aerosol generating article.

[0124] Several examples will now be further described with reference to the accompanying drawings, in which:

[0125] Figure 1 An exemplary embodiment of an aerosol generating system according to the invention is shown in longitudinal cross-section;

[0126] Figure 2 Shown according to Figure 1 Detailed longitudinal cross-section of an aerosol generating system;

[0127] Figure 3 The longitudinal section according to Figure 1 details of the aerosol generating system;

[0128] Figure 4 Shown is the Figure 1 Details of a coil support in an aerosol generating device;

[0129] Figure 5 Shown is the Figure 1 Details of the induction heating device in the aerosol generating device;

[0130] Figure 6 Shown is the Figure 1 Further details of a coil support in an aerosol generating device of;

[0131] Figure 7 shows that it can be used according to Figure 1Details of a first embodiment of power electronics in an aerosol generating device; and

[0132] Figure 8 shows an alternative for use according to Figure 1 Details of a second embodiment of power supply electronics for an aerosol generating device.

[0133] Figure 1-3 A schematic cross-sectional view of an aerosol generating system 1 according to an exemplary embodiment of the present invention is shown. The system 1 is configured to generate an inhalable aerosol by inductively heating a susceptor in thermal contact with a liquid aerosol-forming substrate 25, which is hereinafter also indicated as aerosol-forming liquid 25. The system 1 comprises two main components: an aerosol-generating article 2 and an aerosol-generating device 1 for use with the article 2. While the article 2 comprises a susceptor 22 and an aerosol-forming liquid 25 to be heated, the device 1 comprises a receiving cavity 16 for receiving the article 2, and an inductive heating device 10 configured to generate an alternating magnetic field for inductively heating the susceptor 22 and, thus, for vaporizing the aerosol-forming liquid 25 within the article when the article 2 is inserted into the cavity 16 of the device 1.

[0134] refer to Figure 1 , which shows the device 1 and the article 2 separated from each other, the aerosol generating device 1 comprises a substantially strip-shaped body with a substantially cylindrical device housing 15. In the distal part 4, the device 1 comprises a power source 12, such as a lithium-ion battery, and a circuit system 11, which comprises a controller 160 for controlling the operation of the device 1, in particular for controlling the heating process. In the proximal part 5 opposite to the distal part 4, the device 1 comprises a receiving cavity 16 and at least part of the induction heating device 10. The receiving cavity 16 is an open-ended cavity, which comprises an insertion opening 19 at the proximal end of the device 1, so that the article 2 can be inserted into the receiving cavity 16.

[0135] The induction heating device 10 includes an induction coil 13 for generating an alternating magnetic field in a cavity 16. The induction coil 13 is a cylindrical-spiral coil circumferentially surrounding the cylindrical receiving cavity 16. In the present embodiment, the induction coil 13 has an axial length of about 8 mm and is formed by a single layer of 4.25 turns of coil wire having a circular cross-section. The turns of the induction coil 13 extend along the length extension of the cavity 16. Preferably, there is a gap between adjacent turns of the induction coil 13. That is, the pitch of the spiral induction coil 13 can be greater than the diameter of the coil wire. Therefore, the coil wires of adjacent turns do not contact each other, which allows the use of coil wires without wire insulation. However, the coil wire in the present embodiment is an enamel-coated copper wire with a diameter of 1.1 mm. In addition, the gap between adjacent turns of the induction coil is used for better heat dissipation, and thus the resistive power loss in the coil winding is smaller. In the present embodiment, the (center-to-center) distance between adjacent parts of the coil wires of adjacent turns is about 1.1 times the diameter of the coil wire. These ranges have been shown to provide a sufficiently large distance (which still allows a compact coil design), ie a sufficiently large number of turns per length unit.

[0136] The induction coil 13 is a part of the induction module 30. In addition to the induction coil 13, the induction module also includes a coil support 17 arranged in the device housing 15 for supporting the induction coil 13. The details of the coil support 17 are shown in FIG. Figure 4 The coil support 17 comprises a cylindrical support tube 32 and a circumferential collar 33 at each axial end of the support tube 32. The distal collar 33 comprises a recess or feed-through opening 34 for passing a connecting lead 60 to the induction coil 13, such as Figure 5 As shown in Figure 1-3 It can be seen that the inner space of the support tube 32 at least partially forms 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 along the inner circumference of the support tube 32 forms at least a portion of the inner surface of the receiving cavity 16. Regarding simple and cheap manufacturing, the coil support 17 can be made of plastic. In the case where the induction heating module 30 must comply with specific regulatory requirements, the coil support 17 can be made of bisphenol A-free plastic, for example.

[0137] In addition to the induction coil 13, the induction heating device 10 comprises power supply electronics which can be at least partially integrated in the circuit system 11 and connected via the connecting pads 131 (see Figure 1 ) is coupled to the induction coil 13. In conjunction with the induction coil 13, the power supply electronics are used to generate a high frequency alternating current through the induction coil 13, which causes the induction coil 31 to generate a high frequency changing magnetic field within the interior space of the induction coil 12 and thus within the cavity 16, such as Figure 2The frequency of the high-frequency changing magnetic field may be in the range between 500kHz (kilohertz) and 30MHz (megahertz), in particular between 5MHz (megahertz) and 15MHz (megahertz), preferably between 5MHz (megahertz) and 10MHz (megahertz). As will be described in more detail below, the alternating magnetic field is used to induce at least one of heat-generating eddy currents or hysteresis losses in the susceptor 22 of the article 2 so as to vaporize the aerosol-forming liquid 25 contained in the article 2.

[0138] Next to device 1, Figure 1 Details of the aerosol-generating article 2 are also shown. In this embodiment, the article 2 is a cartridge having a mushroom-type shape that can be coupled to the device 1. At the 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 FIG. Figure 2 and Figure 3 In the evaporation portion 29, the article 2 includes a susceptor 22, which is arranged in the article 2 so that when the evaporation portion 29 of the article 2 is inserted into the cavity 16, the susceptor 22 is located in the inner space of the induction coil 13. Therefore, the susceptor 22 can experience the alternating magnetic field generated by the induction coil 13 during the operation of the heating device 10 so as to be heated.

[0139] In the present embodiment, the susceptor 22 is a flat sheet mesh made of ferromagnetic stainless steel that can be inductively heated. Therefore, the susceptor 22 can also be represented as a sheet mesh susceptor 22 that can perform two functions: wicking (transporting) and heating the aerosol-forming liquid 25. Since the material of the susceptor 22 at hand is 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.

[0140] The susceptor web 22 is in fluid communication with the aerosol-forming liquid 25 contained in the reservoir 24 of the article 2 by means of a wicking porous element 28. The wicking porous element 28 is in direct contact with the liquid 25 in the reservoir 24 and is configured to transport the liquid 25 to the mesh susceptor 22. Thus, the susceptor web 22 is continuously humidified. Figure 2 and Figure 3 ) and the heating device 10 is activated, the mesh susceptor 22 is heated until a temperature sufficient to vaporize the aerosol-forming liquid 25 in contact with the mesh susceptor 22 is reached.

[0141] As especially in Figure 1As can be further seen in the figure, the mesh susceptor 22 is arranged in an air flow channel 26 passing through the article 2 along its central axis. The air flow channel 26 has an air inlet at the distal end of the article 2 and an outlet at the proximal end of the article 2: the outlet is formed by the mouthpiece 21, on which the user can draw. Thus, when the user draws at the mouthpiece 21 when using the system, air is entrained into the air flow channel 26 via the air inlet and passes along the mesh susceptor 22. There, vaporized material of the aerosol-forming liquid is entrained into the air flow through the air flow channel 26. Subsequently, when passing further downstream in the air flow channel 26 towards the mouthpiece 21, the air flow comprising the vaporized material cools so as to form an aerosol that escapes the article 2 through the outlet at the mouthpiece 21.

[0142] The aerosol generating device 1 according to the present embodiment further comprises a puff detector 14 for detecting a user's puff. The puff detector 14 is operatively connected to the power supply electronics so that the occurrence of a puff detected by means of the puff detector 14 triggers the delivery of power to the induction coil 13 for generating an aerosol. In this regard, the aerosol generating device 1 according to the present embodiment can be represented as an on-demand puff device. Once the user stops puffing, the power delivery to the induction coil is interrupted so that unnecessary unused aerosol is not generated. That is, the induction heating device operates intermittently according to the needs of the user.

[0143] While in a continuous mode of operation the susceptor will be permanently maintained at a temperature level sufficient to form a satisfactory amount of aerosol, if the heating device is to be operated intermittently, for example according to user demand (puff on demand), achieving sufficient temperature levels within short periods of time may be a challenge.

[0144] In order to achieve higher heating efficiency, in particular, to reach a sufficient temperature level in a shorter period of time, the induction heating device 10 of the present embodiment includes a flux concentrator 50, which is arranged around the induction coil 13 and configured to distort the alternating magnetic field of the induction heating device 10 toward the inner space of the induction coil 13 during use. To this end, the flux concentrator 50 has a specific configuration, which includes a sleeve portion 52 circumferentially surrounding the induction coil 13, and further includes an annular protrusion portion 51 protruding radially inwardly beyond the sleeve portion 51 at each axial end of the sleeve portion 52, so that the induction coil 13 is axially arranged between the annular protrusion portions 51, such as particularly at Figure 1 and Figure 2 Thus, as seen in a longitudinal section through the flux concentrator 50 along the length axis of the induction coil 13 (see Figure 1 and Figure 2), the flux concentrator 50 has a U-shape or C-shape, wherein the sleeve portion 52 is part of the base of the U-shape or C-shape, and the annular protrusion portion 51 is part of the arm or leg of the U-shape or C-shape. In this regard, it has been found that by distorting the magnetic field toward the interior space of the induction coil 13 using the flux concentrator 50 shaped as described above, the density of the magnetic field at the location of the susceptor 22 can be increased. In particular, the annular protrusion portion 51 protruding radially inwardly beyond the sleeve portion 52 at each axial end of the sleeve portion 52 causes the magnetic field to be concentrated or focused within the interior space of the induction coil 13. Therefore, the level of heat generated in the susceptor 22 for a given power level passing through the induction coil 13 is increased compared to an induction coil without a flux concentrator or only a sleeve-shaped flux concentrator without an annular protrusion portion at each axial end. In addition to this, the flux concentrator 50 acts as a magnetic shield that can reduce the extent to which the magnetic field propagates beyond the induction coil 13. Thus, the flux concentrator 50 may help reduce undesired heating of other sensitive portions of the system or sensitive items external to the apparatus 1 .

[0145] Although the annular protrusion 51 should extend radially inward beyond the outer circumference of the induction coil 13 in order 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 circumference of the induction coil 13, that is, if the annular protrusion does not protrude radially inward beyond the inner circumference of the induction coil 13.

[0146] In the present embodiment, the flux concentrator 50 is constructed of a flux concentrator foil. More specifically, each of the annular protrusions 51 is made of a flux concentrator foil that is spirally wound in multiple layers on the coil support 17 so as to extend radially outward beyond the circumference of the induction coil 13. On top of the annular protrusions 51, a sleeve portion 52 is formed of several layers of the same flux concentrator foil material so as to surround the induction coil 13 and each of the annular protrusions 51. By way of example, a flexible three-layer ferrite sheet comprising a ferrite layer sandwiched between an adhesive layer and a cover layer can be used as the flux concentrator foil, which is available from Laird Company under the product name MHLL6060-300. MHLL6060-300 has a foil thickness of about 90 microns, a real magnetic permeability of about 130 at a frequency of 13.56 MHz, and an imaginary magnetic permeability of about 5. On hand, Figure 1-3Each of the annular protrusions 51 shown in the figure has a height dimension of 2 mm (in the radial direction) and a width dimension of 2 mm (in the axial direction). The sleeve portion 52 has a thickness dimension of about 180 microns (in the radial direction) and a width dimension of 10 mm (in the axial direction). Therefore, using a foil material with a foil thickness of 90 microns requires about 22 windings to form an annular protrusion 51 with a height of 2 mm, and requires about 2 windings to form a sleeve portion 52 with a thickness of 180 microns.

[0147] The sleeve portion 52 is spaced apart from the induction coil 13 in the radial direction by a radial gap having a width (radial extension) in the range between 0.5 mm and 1.5 mm, in particular between 0.8 mm and 1 mm. Advantageously, the radial gap may help avoid heat loss from the induction coil to the sleeve portion to reduce losses in the induction coil and increase losses in the susceptor 22 to be heated, i.e., increase the heating efficiency of the aerosol generating device 1. Likewise, each of the annular protruding portions 51 is spaced apart from the induction coil 13 in the axial direction by an axial gap. The radial gap and / or the axial gap may be an air gap or a gap at least partially filled with a filling material.

[0148] like Figure 6 As shown in FIG, the more distal annular protruding portion 51 comprises a recess or feed-through opening 501 for passing a connecting lead 60 for the induction coil. The recess or feed-through opening 501 may be cut into the annular protruding portion 51 after winding the flux concentrator foil.

[0149] In particular, with regard to the flat sheet-like shape of the susceptor 22, it has been found that the heating efficiency can be further improved by adapting the geometry of the magnetic field within the inner space of the induction coil 13 where the susceptor 22 is to be placed to the flat shape of the susceptor 22. In particular, it has been found that by making the cross-sectional shape of the induction coil 13 flat, 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 location of the susceptor, which in turn leads to an increase in the heating efficiency. Thus, for a given power level passing through the induction coil, the level of heat generated in the susceptor is increased, which in particular allows to reach the desired temperature level in a shorter period of time. Therefore, in the present embodiment, the outer circumference of the support tube 32 has a non-circular flattened cross-sectional shape (see Figure 4), the non-circular flattened cross-sectional shape is composed of two opposite flat sections 32.1 connected by two opposite at least partially curved sections 32.2. Since the induction coil 13 is wound around the outer circumference 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 circumference of the support tube 32. That is, the cylindrical-spiral induction coil 13 also has a non-circular flattened cross-sectional shape (see Figure 5 ), the non-circular flattened cross-sectional shape consists of two opposing flat sections 13.1 connected by two opposing at least partially curved sections 13.2.

[0150] In this embodiment, the non-circular flattened cross-sectional shape of the support tube 32 and the induction coil 13 is an oblong shape, which is a shape consisting of two semicircles 13.2, 32.2 connected by parallel lines 13.1, 32.1 tangent to their end points. Therefore, the induction coil 13 and the support tube 17 have an oblong-cylindrical shape.

[0151] Due to the parallel and semicircular portions of the oblong shape, the non-circular flattened cross-sectional shape of the induction coil 13 and the support tube 32 includes a short symmetry axis and a long symmetry axis. Figure 5 As indicated by the dash-dotted arrows about the induction coil 13, the short symmetry axis extends between two opposite flat sections 13.1 of the induction coil 13, while the long symmetry axis extends between two opposite curved sections 13.2 of the induction coil. Preferably, the ratio of the maximum distance between two opposite at least partially curved sections 13.2, 32.2 along the long symmetry axis to the maximum distance between two opposite flat sections 13.1, 32.1 along the short symmetry axis is in the range between 1.2 and 3, in particular between 1.5 and 2.5. These ratios are particularly advantageous in terms of a proper matching between the geometry of the magnetic field and the flat shape of the susceptor 22 to be heated. Similar to the support tube 32 and the induction coil 13, the flux concentrator 50 may also have a non-circular flattened cross-sectional shape corresponding to the non-circular flattened cross-sectional shapes of the support tube 32 and the induction coil 13. In particular, the cross-sectional shape of the flux concentrator 50 may be oblong.

[0152] In order to further improve the heating efficiency, the outer periphery of the support tube 32 of this embodiment includes a spiral wire concave pattern 39, such as Figure 4 and Figure 6 , the coil wire is received in said spiral wire recess pattern. Advantageously, the wire recess pattern 39 allows a further reduction in the radial distance between the induction coil 13 and the susceptor location within the interior space of the induction coil 13. As already described above, the reduced radial distance results in an increase in the magnetic field strength at the susceptor location, which in turn results in an increase in the heating efficiency.

[0153] The greater the depth of the recesses of the wire recess pattern 39, the better the magnetic field strength at the susceptor position in the internal space of the induction coil 13. For example, in the case where the coil wire has a circular cross-section, the depth of the recesses of the wire recess pattern 39 in the radial direction is preferably in the range between 0.2 and 0.8 times, particularly between 0.3 and 0.5 times, the diameter of the coil wire. Figure 6 As indicated in FIG. 1 , the distance between the induction coil 13 and the inner periphery of the coil support 17 in the radial direction may be in the range of 0.1 mm to 1 mm, in particular, 0.2 mm to 0.5 mm, preferably about 0.3 mm. This ensures a specific short radial distance between the induction coil 13 and the inner space of the susceptor 22 to be received of the support tube 32. That is, the distance between the inner periphery of the support tube 32 and the bottom of the recessed pattern 39 in the radial direction is in the range of 0.1 mm to 1 mm, in particular, 0.2 mm to 0.5 mm, preferably about 0.3 mm.

[0154] like Figure 2 and Figure 6 As shown in , the outer circumference of the support tube 32 may further include a flux concentrator recess 38 for each of the annular protrusions 51 of the flux concentrator 50, in which the radially inward end of the corresponding annular protrusion 51 is received. Thus, the annular protrusions 51 are securely supported, which helps prevent the flux concentrator 50 from being displaced. Otherwise, the displacement may cause an undesirable change in the inductance of the induction coil 13 and an undesirable change in the magnetic field density in the internal space of the induction coil 13.

[0155] Figure 7 Shows the available Figure 1-3 Further details of the induction heating device 10, in particular the power supply electronics, in the aerosol generating device shown in FIG. According to the present embodiment, the induction heating device 10 comprises a DC / AC inverter connected to Figure 1 The DC power supply 12 shown in FIG. The DC / AC inverter includes a class E power amplifier, which in turn includes the following components: a transistor switch 111, which includes a field effect transistor T (FET), such as a metal oxide semiconductor field effect transistor (MOSFET); a transistor switch supply circuit, which is indicated by an arrow 112, for supplying a switching signal (gate-source voltage) to the transistor switch 111; and an LC load network 113 including a shunt capacitor C1 and a series connection of a capacitor C2 and an inductor L2. The inductor L2 corresponds to Figure 1-3 The induction coil 13 shown in FIG. 1 is used to generate an alternating magnetic field in the cavity 16. In addition, a choke L1 for supplying a DC power supply voltage +V_DC from the DC power supply 12 is provided. Figure 7Also shown is an ohmic resistance R representing a total equivalent resistance or total resistive load 114, which is the sum of the ohmic resistance of the induction coil 13, referenced L2, and the ohmic resistance of the susceptor 22 when the system is in use, i.e. when the product 2 is inserted into the cavity 16 of the device 1. Otherwise, in the case where no product is inserted into the cavity 16, the equivalent resistance or resistive load 114 corresponds only to the ohmic resistance of the induction coil 13.

[0156] Figure 8 Another embodiment of a power supply electronic device is shown, which can alternatively be used for Figure 1-3 In the aerosol generating device shown in , a high-frequency oscillating current is provided to the induction coil 13 . Figure 8 The configuration shown in corresponds to the configuration of a class D amplifier. There, a DC power supply 12 is connected to two transistors 1210, 1212. Two switching elements 1220, 1222 are provided for switching the two transistors 1210, 1212 on and off. The switching elements 1220, 1222 are controlled at high frequency in a way so as to ensure that one of the two transistors 1210, 1212 has been switched off when the other of the two transistors is switched on. The induction coil 13 for generating an alternating magnetic field for induction heating is again indicated by L2, while the combined ohmic resistance of the induction coil 13 and the susceptor 22 is indicated by R, the values ​​of C1 and C2 being selected to maximize the efficient dissipation of power in the susceptor element. The capacitor C1 is not necessary for configuring the architecture as class D and can therefore be omitted.

[0157] For the purpose of this specification and the appended claims, unless otherwise indicated, all numbers representing amounts, quantities, percentages, etc. should be understood to be modified by the term "about" in all cases. Moreover, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein that may or may not be specifically listed herein. Therefore, in this context, the number A is understood to be A±5%A. In this context, the number A can be regarded as including a value within the general standard error for the measurement of the attribute modified by the number A. In certain cases used in the appended claims, the number A may deviate from the percentages listed above, provided that the amount of A deviation does not substantially affect the basic features and novel features of the invention claimed for protection. Moreover, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein that may or may not be specifically listed herein.

Claims

1. An induction heating module for an induction heating aerosol generating device, the induction heating module comprising an induction heating device, the heating device comprising: a single cylindrical-helical induction coil for generating an alternating magnetic field allowing inductive heating of a susceptor within an interior space of the induction coil so as to heat an aerosol-forming substrate in thermal contact or proximity with the susceptor; a flux concentrator arranged around the induction coil and configured to distort the alternating magnetic field of the induction heating device towards the inner space of the induction coil during use, wherein the flux concentrator comprises a sleeve portion circumferentially surrounding the induction coil and an annular protrusion portion protruding radially inwardly beyond the sleeve portion at each axial end of the sleeve portion, wherein the induction coil is axially arranged between the annular protrusion portions; - a coil support on which the induction coil and the flux concentrator are supported, wherein the coil support comprises a support tube, wherein the induction coil is arranged around the outer circumference of the support tube, and wherein the outer circumference of the support tube comprises a flux concentrator recess for each of the annular protruding portions of the flux concentrator, in which a radially inward end of the respective annular protruding portion is received. 2 . The induction heating module according to claim 1 , wherein the flux concentrator comprises or is made of one or more layers of flux concentrator foil.

3. The induction heating module according to claim 1 , wherein each of the annular protrusions is made of one or more layers of flux concentrator foil, the one or more layers of the annular protrusions extending in a radially outward direction at least to the outer circumference of the induction coil, preferably extending beyond the outer circumference of the induction coil, and wherein the sleeve portion is made of one or more layers of flux concentrator foil surrounding the induction coil and each of the annular protrusions; or wherein the sleeve portion is made of one or more layers of flux concentrator foil surrounding the induction coil, and wherein each of the annular protrusions is made of one or more layers of flux concentrator foil to end flush with the outer circumference of the sleeve portion in a radial direction.

4. An induction heating module for an induction heating aerosol generating device, the induction heating module comprising an induction heating device, the heating device comprising: a single cylindrical-helical induction coil for generating an alternating magnetic field allowing inductive heating of a susceptor within an interior space of the induction coil so as to heat an aerosol-forming substrate in thermal contact or proximity with the susceptor; a flux concentrator arranged around the induction coil and configured to distort the alternating magnetic field of the induction heating device towards the inner space of the induction coil during use, wherein the flux concentrator comprises a sleeve portion circumferentially surrounding the induction coil and an annular protrusion portion protruding radially inwardly beyond the sleeve portion at each axial end of the sleeve portion, wherein the induction coil is axially arranged between the annular protrusion portions, wherein the flux concentrator comprises or is made of one or more layers of flux concentrator foil, wherein each of the annular protruding portions is made of one or more layers of flux concentrator foil extending in radially outward direction at least to, preferably beyond, the outer circumference of the induction coil, and wherein the sleeve portion is made of one or more layers of flux concentrator foil surrounding the induction coil and each of the annular protruding portions; or wherein the sleeve portion is made of one or more layers of flux concentrator foil surrounding the induction coil, and wherein each of the annular protruding portions is made of one or more layers of flux concentrator foil to end flush with the outer circumference of the sleeve portion in radial direction. 5 . The induction heating module according to claim 1 , wherein each of the annular protruding portions is spaced apart from the induction coil by an axial gap in the axial direction.

6. An induction heating module for an induction heating aerosol generating device, the induction heating module comprising an induction heating device, the heating device comprising: a single cylindrical-helical induction coil for generating an alternating magnetic field allowing inductive heating of a susceptor within an interior space of the induction coil so as to heat an aerosol-forming substrate in thermal contact or proximity with the susceptor; a flux concentrator arranged around the induction coil and configured to distort the alternating magnetic field of the induction heating device towards the inner space of the induction coil during use, wherein the flux concentrator comprises a sleeve portion circumferentially surrounding the induction coil and an annular protrusion portion protruding radially inwardly beyond the sleeve portion at each axial end of the sleeve portion, wherein the induction coil is axially arranged between the annular protrusion portions, and Each of the annular protrusions is spaced apart from the induction coil by an axial gap in the axial direction.

7. The induction heating module according to any one of the preceding claims, wherein the sleeve portion is spaced apart from the induction coil by a radial gap in a radial direction.

8. The induction heating module according to any one of the preceding claims, wherein the annular protrusion portion extends radially inwardly beyond the outer circumference of the induction coil.

9. The induction heating module according to any one of the preceding claims, wherein the annular protrusion portion extends radially inwardly at most to the inner periphery of the induction coil.

10. The induction heating module according to any one of the preceding claims, wherein a width dimension of each of the annular protruding portions in the axial direction is in the range between 1.5 mm and 2.5 mm, in particular between 1.8 mm and 2.2 mm.

11. The induction heating module according to any one of the preceding claims, wherein a height dimension of each of the annular protruding portions in the radial direction is in a range between 1.5 mm and 2.5 mm, in particular between 1.8 mm and 2.2 mm.

12. The induction heating module according to any of the preceding claims, wherein a thickness dimension of the sleeve portion in the radial direction is in the range between 100 and 500 microns, in particular between 150 and 250 microns.

13. An induction heating module according to any of the preceding claims, wherein the cylindrical-helical induction coil, and preferably, if present, the outer periphery of the support tube, has a non-circular flattened cross-sectional shape, the non-circular flattened cross-sectional shape comprising, in particular consisting of, two opposite flat sections connected by two opposite at least partially curved sections; and preferably wherein the flux concentrator has a non-circular flattened cross-sectional shape corresponding to the non-circular flattened cross-sectional shape of the induction coil.

14. An induction heating aerosol generating device for use with an aerosol generating article, the article comprising an aerosol-forming substrate to be heated by the interaction of a susceptor with an alternating magnetic field provided by the aerosol generating device, wherein the device comprises an induction heating module according to any one of claims 1 to 13.

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, the article comprising an aerosol-forming substrate to be heated by the interaction of a receptor with an alternating magnetic field provided by the aerosol generating device.

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