Aerosol generating device for generating aerosols by inductive heating of an aerosol-forming substrate - Patent Application 20070122997

Abstract

The present disclosure relates to an aerosol generating device for generating an aerosol by inductively heating an aerosol-forming substrate. The device comprises a device housing having a cavity configured to removably receive an aerosol-forming substrate to be heated. The device further comprises an induction heating arrangement including at least one induction coil for generating a varying magnetic field within the cavity, the induction coil being disposed around at least a portion of the receiving cavity. In addition, the device comprises a magnetic flux concentrator disposed around at least a portion of the induction coil and configured to deflect the varying magnetic field of the at least one induction heating arrangement toward the cavity during use of the device. The magnetic flux concentrator comprises a multilayer magnetic flux concentrator foil having at least one magnetic layer laminated with at least a first support layer, the magnetic layer comprising a plurality of separated pieces of a soft magnetic alloy. The present disclosure further relates to an aerosol generating system comprising such a device and an aerosol-generating article, the article including an aerosol-forming substrate to be heated. Furthermore, the present disclosure relates to a method for manufacturing the multilayer magnetic flux concentrator foil of such a device.

Description

[Technical Field]

[0001] The present disclosure relates to an aerosol-generating device for generating an aerosol by inductive heating of an aerosol-forming substrate, the device comprising a magnetic flux concentrator foil. The present disclosure further relates to an aerosol-generating system comprising such a device and an aerosol-generating article, the article comprising an aerosol-forming substrate to be heated. Furthermore, the present disclosure relates to a method for manufacturing the multilayer magnetic flux concentrator foil of such a device. [Background technology]

[0002] Aerosol-generating systems for inductively heating an aerosol-forming substrate capable of forming an inhalable aerosol are generally known in the prior art. Such systems may include an aerosol-generating device having a cavity for receiving the substrate to be heated. The substrate may be an integral part of an aerosol-generating article configured for use in the device. To heat the substrate, the device may include an induction heating arrangement including an induction coil for generating a varying magnetic field within the cavity. The magnetic field is used to induce at least one of heat-generating eddy currents or hysteresis losses in a susceptor that is disposed in thermal proximity to or in direct physical contact with the substrate to be heated during use of the system. Generally, the susceptor may be an integral part of either the device or the article.

[0003] The magnetic field not only inductively heats the susceptor, but can also interfere with other sensitive parts of the aerosol generating device or sensitive external items in close proximity to the device. To reduce such undesirable interference, the aerosol generating device may be provided with a magnetic flux concentrator disposed around the induction heating arrangement, which acts to substantially confine the magnetic field generated by the heating arrangement within the volume enclosed by the magnetic flux concentrator. However, it has been observed that the containment effect is often reduced or lost if the device is subjected to an excessive force or shock, for example, after being accidentally dropped. In addition, many magnetic flux concentrators are quite bulky and can significantly increase the overall bulk and size of the aerosol generating device. Furthermore, it has been observed that the magnetic flux concentrator itself undesirably heats the device during use, particularly when the device is operated in magnetic fields varying in the megahertz range.

[0004] It would therefore be desirable to have an aerosol generating apparatus and system for inductively heating an aerosol-forming substrate that possesses the advantages of prior art solutions while mitigating their limitations. In particular, it would be desirable to have an aerosol generating apparatus and system that includes a magnetic flux concentrator with enhanced robustness and a compact design, yet that does not heat up significantly during use of the apparatus. Summary of the Invention

[0005] According to one aspect of the present invention, there is provided an aerosol generating device for generating an aerosol by inductively heating an aerosol-forming substrate. The device comprises a device housing having a cavity configured to removably receive an aerosol-forming substrate to be heated. The device further comprises an induction heating arrangement including at least one induction coil for generating a varying magnetic field within the cavity, the induction coil being disposed around at least a portion of the receiving cavity. Additionally, the device comprises a magnetic flux concentrator disposed around at least a portion of the induction coil and configured to distort the varying magnetic field of the at least one induction heating arrangement toward the cavity during use of the device. The magnetic flux concentrator comprises a multilayer magnetic flux concentrator foil having at least one magnetic layer laminated with at least a first support layer, the magnetic layer comprising a plurality of separated pieces of a soft magnetic alloy.

[0006] In accordance with the present invention, it has been discovered that magnetic flux concentrators including or made of magnetic flux concentrator foil are more flexible than other magnetic flux concentrator configurations, such as solid ferrite bodies. Therefore, magnetic flux concentrator foils offer good shock absorption properties and can withstand higher excessive force impacts or shocks without cracking. Compared to susceptors made from sintered ferrite powder, for example, flexible magnetic flux concentrator foils offer significantly improved resistance to shock loads, such as those resulting from accidental drops. Furthermore, magnetic flux concentrator foils, due to their small dimensions, enable more compact designs of aerosol generating devices. In particular, compared to sintered ferrite magnetic flux concentrators, magnetic flux concentrator foils can be made significantly thinner. Furthermore, in contrast to solid magnetic flux concentrators, magnetic flux concentrator foils allow for compensation for manufacturing tolerances and fine-tuning of the inductivity. In particular, magnetic flux concentrator foils can advantageously help enhance the impedance stability of induction coils over temperature. Generally, the impedance of an induction coil is affected by the presence of a flux concentrator. When using a flux concentrator foil, the conductance of the induction heating system may change less with temperature due to the small volume of the foil, especially compared to a large-volume solid flux concentrator. As a result, the impedance may also change less with temperature. Additionally, flux concentrator foils are easier to manufacture.

[0007] Most importantly, because the magnetic layer includes multiple separated segments, the formation of eddy currents in the magnetic layer is partially prevented because each single segment provides only a limited space in which eddy currents can form. That is, compared to a non-segmented magnetic layer, the segmented magnetic layer has reduced AC resistance. As a result, there is little or no energy dissipation within the segments, and the magnetic flux concentrator foil as a whole is only slightly heated, if at all. Thus, most of the energy provided by the changing magnetic field is dissipated within the susceptor and, therefore, is effectively used to heat the aerosol-forming substrate within the cavity.

[0008] As used herein, the phrase "concentrate the magnetic field" means that the magnetic flux concentrator is capable of distorting the magnetic field so that the density of the magnetic field increases within the cavity.

[0009] By distorting the magnetic field toward the cavity, the magnetic flux concentrator reduces the extent to which the magnetic field propagates beyond the induction coil. That is, the magnetic flux concentrator acts as a magnetic shield. This can reduce unwanted heating of adjacent sensitive parts of the device (e.g., the metal outer housing) or adjacent sensitive items outside the device. By reducing unwanted heating losses, the efficiency of the aerosol generating device can be further improved.

[0010] Furthermore, by distorting the magnetic field toward the cavity, the magnetic flux concentrator can advantageously concentrate or focus the magnetic field within the cavity. This can increase the level of heat generated in the susceptor for a given level of power passed through the induction coil compared to an induction coil without a magnetic flux concentrator. Therefore, the efficiency of the aerosol generation device can be improved.

[0011] As used herein, the term "foil" refers to a thin sheet material having a thickness that is much smaller than any dimension perpendicular to the thickness direction. As used herein, the term "thickness" refers to the dimension of the foil perpendicular to the major surface of the foil. The magnetic flux concentrator foil may have a thickness in the range of 0.02 millimeters to 0.25 millimeters, particularly 0.05 millimeters to 0.2 millimeters, and preferably 0.1 millimeters to 0.15 millimeters. For example, the magnetic flux concentrator foil may have a thickness of 62 micrometers. The magnetic flux concentrator foil may have a thickness of up to 150 micrometers, particularly up to 100 micrometers, and preferably up to 80 micrometers. These thickness values ​​allow for a particularly compact design of the aerosol generating device. Furthermore, these values ​​are large enough to sufficiently deflect the alternating magnetic field of the induction heating arrangement toward the cavity during use of the device.

[0012] The thickness of the magnetic flux concentrator may be substantially constant along any direction perpendicular to the thickness of the magnetic flux concentrator. In other embodiments, the thickness of the magnetic flux concentrator may vary along one or more directions perpendicular to the thickness of the magnetic flux concentrator. For example, the thickness of the magnetic flux concentrator may taper or decrease from one end to the other, or from a central portion of the magnetic flux concentrator toward both ends. The thickness of the magnetic flux concentrator may be substantially constant around its periphery. In other embodiments, the thickness of the magnetic flux concentrator may vary around its periphery.

[0013] The magnetic layer may have a layer thickness in the range of 15 micrometers to 100 micrometers, in particular 18 micrometers to 40 micrometers, for example 20 micrometers. The magnetic layer may have a layer thickness of up to 100 micrometers, in particular up to 50 micrometers, preferably up to 40 micrometers. The magnetic layer may have a layer thickness of up to 75%, in particular 50%, more particularly at least 40%, preferably at least 35% of the layer thickness of the magnetic flux concentrator foil.

[0014] Advantageously, the first support layer functions to bond and support the pieces laminated thereto. Preferably, the multilayer magnetic flux concentrator foil may further comprise a second support layer facing the first support layer on a side of at least one magnetic layer, or, as further described below, on a side of a plurality of adjacent magnetic layers. Like the first support layer, the second support layer is preferably laminated with at least one magnetic layer, or, if applicable, a plurality of adjacent magnetic layers. Advantageously, the second layer is also used to bond and support the pieces.

[0015] At least the first support layer, and, if present, the second support layer substrate layer, may comprise a polymeric film. The polymeric film may be selected from polyester, polyimide, polyolefin, or a combination thereof. The substrate layer may comprise a release liner. Preferably, at least one of the first support layer and, if present, the second support layer may be one of an adhesive layer, an electrically insulating layer, or an electrically insulating adhesive layer. The use of an electrically insulating adhesive layer advantageously avoids shorting of fragments within at least one magnetic layer, or, if applicable, multiple adjacent magnetic layers adjacent to the first or second support layer, respectively.

[0016] The first support layer, and, if present, the second support layer, may be an edge layer of the multilayer magnetic flux concentrator foil, i.e., one of the two outermost layers of the multilayer magnetic flux concentrator foil.

[0017] As used herein, the term "magnetic" refers to either ferromagnetic or ferrimagnetic, i.e., soft magnetic alloys are either ferromagnetic or ferrimagnetic.

[0018] As used herein, the term "soft magnetic alloy" refers to a magnetic alloy having a low magnetic coercivity, in particular a magnetic coercivity of at most 100 A / m (amperes per meter), preferably at most 50 A / m (amperes per meter), more preferably at most 10 A / m (amperes per meter), and most preferably at most 5 A / m (amperes per meter). Magnetic coercivity is a measure of the ability of a magnetic material to withstand an external magnetic field without being demagnetized. Due to the low magnetic coercivity, soft magnetic alloys advantageously have low hysteresis loss.

[0019] The soft magnetic alloy is preferably brittle, which is advantageous in terms of cracking the soft magnetic alloy into multiple separated pieces.

[0020] The soft magnetic alloy of the flux concentrator foil may include or be made from any material or combination of materials suitable for distorting a magnetic field.

[0021] Preferably, the soft magnetic alloy may be a metallic glass (amorphous metal) or a nanocrystalline soft magnetic alloy, particularly a nanocrystalline Fe-based soft magnetic alloy.

[0022] Particularly, the soft magnetic alloy of the magnetic flux concentrator foil is Fe 100-a-b-c-x-y-z Cu a M b T c Si x Z z and a composition of these and up to 0.5 atomic% of foreign substances, or may contain these, M is one or more of the group consisting of Nb, Mo and Ta, T is one or more of the group consisting of V, Cr, Co and Ni, Z is one or more of the group consisting of C, P and Ge, and 0.5 atomic% < a < 1.5 atomic%, 2 atomic% ≤ b < 4 atomic%, 0 atomic% ≤ c < 5 atomic%, 12 atomic% < x < 18 atomic%, 5 atomic% < y < 12 atomic%, and 0 atomic% ≤ z < 2 atomic%.

[0023] For example, the soft magnetic alloy of the magnetic flux concentrator foil may include an alloy sold under the trademarks Vitrovac or Vitroperm by VACUUMSCHMELZE GmbH & Co. KG (Germany), or may be made of this alloy. The Vitroperm alloy is a nanocrystalline soft magnetic alloy. For example, the magnetic flux concentrator foil may include Vitroperm 220, Vitroperm 250, Vitroperm 270, Vitroperm 400, Vitroperm 500, or Vitroperm 800, or may be made of them. Particularly, the soft magnetic alloy is Fe 73.8 Nb3Cu1Si 15.6 B 6.6 and may be a composition of these, or may contain this. This composition corresponds to Vitroperm 800.

[0024] As used herein, the term "magnetic flux concentrator" refers to a component having a high relative permeability that acts to concentrate and direct the magnetic field or lines of force generated by an induction coil. As used herein, the term "high relative permeability" refers to a relative permeability of at least 100, particularly at least 1,000, preferably at least 10,000, even more preferably at least 50,000, and most preferably at least 80,000. These exemplary values ​​refer to maximum relative permeability values ​​at frequencies up to 50 kHz and temperatures of 25°C. The term "relative permeability" refers to the ratio of the permeability of a material or medium, such as a magnetic flux concentrator, to the permeability of free space, μ, where μ is 4π 10 -7 N.A. -2 (4 Pi ​​10E-07 Newtons per square ampere). Accordingly, it is preferred that the soft magnetic alloy have a relative permeability of at least 100, in particular at least 1000, preferably at least 10000, even more preferably at least 50000, and most preferably at least 80000. These values ​​preferably refer to the maximum relative permeability at a frequency of up to 50 kHz and a temperature of 25°C.

[0025] As described in more detail below with respect to the method of the present invention, the fragmented magnetic layer can result from a multilayer magnetic flux concentrator foil having at least one magnetic layer of a soft magnetic alloy laminated with at least a first support layer, where the magnetic layer cracks into a plurality of separated pieces. Cracking of the magnetic layer can be achieved, for example, by applying an external force to the magnetic flux concentrator foil in a direction transverse to the plane of the foil. The magnetic layer cracks into a plurality of pieces, but the first support layer, and, if present, the second support layer, remain intact and do not crack into pieces to hold the fragmented magnetic layer together.

[0026] Depending on the tool and method used to crack the magnetic layer into fragments, the multiple separated fragments may be arranged in a pattern including multiple crack centers, with the multiple cracks extending radially outward from each crack center in a web-shaped pattern.

[0027] Also, depending on the tools and methods used, the fragments may have different kinds of shapes, for example, the fragments may have a flake-like shape.

[0028] Preferably, each single piece may have a piece size of at most 1 millimeter, in particular at most 750 micrometers, or at most 500 micrometers. Similarly, the multiple separated pieces may have an average piece size of at most 1 millimeter, in particular at most 750 micrometers, or at most 500 micrometers. Such piece size values ​​allow for a further reduction in the AC resistance of the magnetic layer and therefore a further reduction in eddy current losses in the flux concentrator foil.

[0029] Generally, a multi-layer magnetic flux concentrator foil may include a single magnetic layer. It is also possible for a multi-layer magnetic flux concentrator foil to include multiple adjacent magnetic layers. Multiple adjacent magnetic layers may enhance the magnetic flux concentrating effect. Furthermore, using a foil with multiple adjacent magnetic layers may reduce the effort of disposing the magnetic flux concentrator foil around the induction coil, since a single winding of the multi-layer magnetic flux concentrator foil may achieve the same effect as a single magnetic layer magnetic flux concentrator foil disposed around the induction coil in multiple windings on top of each other.

[0030] With respect to a magnetic flux concentrator foil having multiple adjacent magnetic layers, the multilayer magnetic flux concentrator foil may include an adhesive film, in particular an electrically insulating adhesive film, disposed between each pair of adjacent magnetic layers. Advantageously, the adhesive film functions to bond and support multiple segments of the various magnetic layers. The use of an electrically insulating adhesive film avoids short-circuiting of segments within one magnetic layer or adjacent layers through the adhesive film. The adhesive film disposed between each pair of adjacent magnetic layers is also referred to as an intermediate support layer. That is, the magnetic flux concentrator foil may also include at least one intermediate support layer. The intermediate support layer may be disposed between a pair of adjacent magnetic layers. More details regarding the method according to the invention are described below and apply equally to the aerosol generating device according to the invention described herein.

[0031] For example, a multi-layer magnetic flux concentrator foil may include the following layers (from bottom to top): - an adhesive (non-PET) first support layer; a first magnetic layer comprising or made of a soft magnetic alloy; - an adhesive (non-PET) intermediate support layer; a second magnetic layer comprising or made of a soft magnetic alloy; - A second adhesive (PET-based) support layer.

[0032] As described in more detail below, the multilayer magnetic flux concentrator foil may be a sealed multilayer magnetic flux concentrator foil. That is, the multilayer magnetic flux concentrator foil may be sealed to prevent fragments from leaking laterally from the foil. To this end, a sealing adhesive tape may be disposed on one or each side of the (non-sealing) magnetic flux concentrator foil, the adhesive sealing tape having a width extension transverse to the opposing (cut) edges of the magnetic flux concentrator foil that is greater than the width extension of the non-sealing magnetic flux concentrator foil in the same direction, i.e., transverse to the opposing cut edges of the (non-sealing) magnetic flux concentrator foil. As a result, the sealing adhesive tape on each side of the (non-sealing) magnetic flux concentrator foil may include laterally protruding wings that may be in adhesive contact with each other to seal the edges of the (non-sealing) magnetic flux concentrator. As an example, a sealed multilayer magnetic flux concentrator foil may include the following layers (from bottom to top): - a first three-layer adhesive sealing laminate comprising a (PEN-based or PI-based) film sandwiched between a first adhesive layer and a second adhesive layer; - an adhesive (non-PET) first support layer; a first magnetic layer comprising or made of a soft magnetic alloy; - an adhesive (non-PET) intermediate support layer; a second magnetic layer comprising or made of a soft magnetic alloy; - a second support layer of adhesive (PET), - A second three-layer adhesive sealing laminate comprising a (PEN-based or PI-based) film sandwiched between a first adhesive layer and a second adhesive layer.

[0033] As another example, a sealed multi-layer magnetic flux concentrator foil may include the following layers (from bottom to top): a first PET-based adhesive film; - an adhesive (non-PET) first support layer; a first magnetic layer comprising or made of a soft magnetic alloy; - an adhesive (non-PET) intermediate support layer; a second magnetic layer comprising or made of a soft magnetic alloy; - a second support layer of adhesive (PET), - The second PET adhesive film.

[0034] The first and second three-layer adhesive sealing laminates may include a PEN (polyethylene terephthalate)-based film sandwiched between the first adhesive layer and the second adhesive layer. Similarly, the three-layer adhesive sealing laminate may include a PI (polyimide)-based film sandwiched between the first adhesive layer and the second adhesive layer. The PEN (polyethylene terephthalate)-based film may have a thickness of 2 to 5 micrometers, particularly 3 micrometers. Similarly, the PI (polyimide)-based film may have a thickness of 2 to 8 micrometers, particularly 5 to 7 micrometers. In total, the three-layer adhesive sealing laminate may have a thickness of 3 to 15 micrometers, particularly 4 to 13 micrometers, for example, 5 micrometers, or 7 micrometers, or 9 micrometers, or 13 micrometers. The first and second adhesive layers of the three-layer sealing adhesive tape may include a non-PET (polyethylene terephthalate)-based adhesive.

[0035] The first and second PET adhesive films may have a thickness of 2 to 5 micrometers, particularly 3 micrometers.

[0036] The adhesive (non-PET-based) first and second support layers and the adhesive (PET-based) third support layer may have a thickness in the range of 2 micrometers to 10 micrometers, in particular in the range of 2 micrometers to 5 micrometers, for example 3 micrometers.

[0037] The first and second magnetic layers may have a thickness in the range of 15 micrometers to 25 micrometers, in particular in the range of 18 micrometers to 23 micrometers, for example 21 micrometers.

[0038] Further details of the various tapes, films, and layers are described further below with respect to the method according to the invention and apply equally to the aerosol generating device according to the invention described herein.

[0039] As used herein, the term "separated fragments" refers to a configuration of a magnetic layer that includes multiple fragments or multiple fragment clusters that are not in direct contact, particularly electrical contact, with adjacent fragments or adjacent fragment clusters, allowing for suppression of eddy current effects.

[0040] The gaps between the separated fragments or fragment clusters may be at least partially filled with an electrically insulating material such as a binder, e.g., a polymer such as silicone. In particular, the gaps between the separated fragments or fragment clusters may be at least partially filled with at least one of the material of the first support layer, or the material of the second support layer, if present, or the material of the adhesive film between adjacent magnetic layers, if present, or with the matrix material (binder) of the soft magnetic alloy. Filling the gaps advantageously keeps the fragments or fragment clusters permanently separated from one another and therefore helps to permanently suppress eddy current effects even if the entire magnetic flux concentrator foil is deformed.

[0041] Furthermore, the aerosol generating device may include a radial gap between at least one induction coil and a magnetic flux concentrator, the magnetic flux concentrator at least partially surrounding the induction coil. The gap may therefore also at least partially surround the induction coil. The gap may have a radial extension in the range of 40 micrometers to 400 micrometers, particularly 100 micrometers to 240 micrometers, e.g., 220 micrometers. Advantageously, the gap may help to reduce losses in the induction coil and increase losses in the heated susceptor, i.e., increase the heating efficiency of the aerosol generating device.

[0042] The gap may be an air gap or a gap at least partially filled with a filler material, e.g., a polyimide such as poly(4,4'-oxydiphenylene-pyromellitic imide), also known as Kapton®, or any other suitable dielectric material. In particular, a first dielectric wrapper may be disposed around at least a portion of the induction coil between the induction coil and the magnetic flux concentrator. For example, the induction coil may be wrapped with one or more layers of Kapton tape to fill the radial gap between at least one induction coil and the magnetic flux concentrator. One layer of Kapton tape may have a thickness ranging from 40 micrometers to 80 micrometers.

[0043] Additionally, the aerosol generating device may include a conductive shielding wrapper disposed around the magnetic flux concentrator, which advantageously functions to shield the environment of the device from the magnetic field within the device.

[0044] Additionally, the aerosol generating device may include a second dielectric wrapper disposed around the magnetic flux concentrator, particularly around the shielding wrapper, if present. Similar to the first dielectric wrapper, the second dielectric wrapper may serve to reduce losses in the induction coil and increase losses in the heated susceptor, i.e., increase the heating efficiency of the aerosol generating device.

[0045] In general, the magnetic flux concentrator may have any shape, and more preferably, a shape that matches the shape of at least one inductor in which the concentrator is at least partially disposed.

[0046] For example, the magnetic flux concentrator may have a substantially cylindrical shape, particularly a sleeve-shaped or tubular shape. That is, the magnetic flux concentrator may be a tubular magnetic flux concentrator, a magnetic flux concentrator sleeve, or a cylindrical magnetic flux concentrator. Such a shape is particularly suitable when the at least one induction coil is a helical induction coil having a substantially cylindrical shape. In such a configuration, the magnetic flux concentrator completely surrounds the at least one induction coil along at least a portion of the axial extension of the coil. A tubular or sleeve shape is particularly advantageous with respect to a hollow cylindrical shape and with respect to a cylindrical and / or helical configuration of the induction coil. With this shape, the magnetic flux concentrator may have any suitable cross-section. For example, the magnetic flux concentrator may have a square, elliptical, rectangular, triangular, pentagonal, hexagonal, or similar cross-sectional shape. Preferably, the magnetic flux concentrator has a circular cross-section. For example, the magnetic flux concentrator may have an annular cylindrical shape.

[0047] The magnetic flux concentrator may also extend only partially around the circumference of the at least one induction coil.

[0048] In any of these configurations, the magnetic flux concentrator is preferably disposed coaxially with the centerline of the at least one induction coil. Even more preferably, the magnetic flux concentrator and the at least one induction coil are coaxial with the centerline of the cavity.

[0049] In general, the induction heating arrangement may comprise a single induction coil or multiple induction coils, particularly two induction coils. In the case of a single induction coil, the magnetic flux concentrator may be disposed around at least a portion of the single induction coil, preferably completely around the induction coil. In the case of multiple induction coils, the magnetic flux concentrator may be disposed around at least a portion of one of the induction coils, preferably around at least a portion of each one of the induction coils, and even more preferably completely around each induction coil.

[0050] The flux concentrator foil may be wound, particularly with overlapping or abutting ends, to form a tubular flux concentrator or flux concentrator sleeve. The overlapping or abutting ends may be attached to one another. Similarly, the overlapping or abutting ends may loosely overlap or abut one another.

[0051] In particular, the flux concentrator foil may be wound with a single turn to form a tubular flux concentrator or flux concentrator sleeve with a single turn of the flux concentrator foil. Alternatively, the flux concentrator foil may be wound with multiple turns / windings to form a tubular flux concentrator or flux concentrator sleeve with multiple, particularly spiral, windings.

[0052] The flux concentrator foil may also be spirally wound axially about the winding axis to form a tubular flux concentrator or flux concentrator sleeve with one or more spiral windings of flux concentrator foil overlapping each other.

[0053] The flux concentrator foils may also be wound with separate concentric windings on top of each other, i.e., the flux concentrator may comprise multiple flux concentrator foils wound with separate concentric single (turn) windings on top of each other. Similarly, the flux concentrator foils may also be wound with separate spiral or multiple windings on top of each other, i.e., the flux concentrator may comprise multiple flux concentrator foils wound with separate concentric multiple spiral or helical (turn) windings on top of each other.

[0054] Furthermore, the magnetic flux concentrator may include multiple magnetic flux concentrator foils arranged adjacent to each other, each magnetic flux concentrator foil wound with a single winding, or with multiple spiral windings that overlap each other, or with separate concentric windings that overlap each other.

[0055] Configurations of magnetic flux concentrator foils including multiple, particularly multiple spiral or helical, windings or multiple separate concentric windings that overlap each other may be advantageously used to create multi-layer magnetic flux concentrators or foils, with each winding corresponding to a layer. For example, a magnetic flux concentrator may include two, three, four, five, six, seven, or more spiral or helical windings or multiple separate concentric windings. Such multi-layer magnetic flux concentrator foils or foils may thus have a thickness that substantially corresponds to the thickness of a single layer or foil multiplied by the number of windings or layers. For example, if the foil has a thickness in the range of 0.02 mm (millimeter) to 0.25 mm (millimeter), in particular 0.05 mm (millimeter) to 0.2 mm (millimeter), preferably 0.1 mm (millimeter) to 0.15 mm (millimeter), a multilayer magnetic flux concentrator foil or multilayer magnetic flux concentrator comprising six layers may have a thickness in the range of 0.12 mm (millimeter) to 1.5 mm (millimeter), in particular 0.3 mm (millimeter) to 1.2 mm (millimeter), preferably 0.6 mm (millimeter) to 0.9 mm (millimeter).

[0056] When the magnetic flux concentrator foil is wound, particularly with a single winding, to form a tubular magnetic flux concentrator or magnetic flux concentrator sleeve, the magnetic flux concentrator foil may be attached to the inner surface of the device housing in a press-fit manner by partial release of the elastic restoring force of the wound magnetic flux concentrator foil. That is, the elastic restoring force presses the magnetic flux concentrator foil radially outward against the inner surface of the device housing. In this configuration, the ends of the wound foil preferably loosely overlap or loosely abut each other. Advantageously, this configuration allows for simple installation of the magnetic flux concentrator, particularly without additional fastening means.

[0057] The magnetic flux concentrator can also result from directly extruding a magnetic flux concentrator foil into its final shape. In particular, the magnetic flux concentrator can comprise or be an extruded magnetic flux concentrator foil, such as an extruded tubular magnetic flux concentrator foil or magnetic flux concentrator foil sleeve, or an extruded cylindrical magnetic flux concentrator foil. The extruded tubular magnetic flux concentrator foil or extruded magnetic flux concentrator foil sleeve or extruded cylindrical magnetic flux concentrator foil can have a wall thickness ranging from 0.05 mm to 0.25 mm, preferably from 0.1 mm to 0.15 mm. The wall thickness can also be in the range of 0.12 mm to 1.5 mm, particularly from 0.3 mm to 1.2 mm, preferably from 0.6 mm to 0.9 mm.

[0058] The induction heating arrangement may include at least one susceptor element that is part of the apparatus. Similarly, the at least one susceptor element can be an integral part of the aerosol-generating article that includes the aerosol-forming substrate to be heated. As part of the apparatus, the at least one susceptor element is disposed or disposable at least partially within the cavity so as to be in thermal proximity or thermal contact, preferably physical contact, with the aerosol-forming substrate during use.

[0059] As used herein, the term "susceptor element" 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 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 switching under the influence of the changing magnetic field. Eddy currents may be induced when the susceptor is electrically conductive. In the case of an electrically conductive ferromagnetic or ferrimagnetic susceptor, heat can be generated by both eddy currents and hysteresis loss.

[0060] Thus, the susceptor element may be formed from any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-forming substrate. Preferred susceptor elements include metal or carbon. Preferred susceptor elements may include a ferromagnetic material (e.g., ferritic iron), or ferromagnetic steel or stainless steel. Suitable susceptor elements may be or include aluminum. Preferred susceptor elements may be formed from 400 series stainless steel, such as grade 410, or grade 420, or grade 430 stainless steel.

[0061] The susceptor element can include a variety of geometric configurations. The susceptor element can include or be a susceptor pin, susceptor rod, susceptor blade, susceptor strip, or susceptor plate. When the susceptor element is part of an aerosol-generating device, the susceptor pin, susceptor rod, susceptor blade, susceptor strip, or susceptor plate can preferably protrude into a cavity of the device toward an opening of the cavity for inserting an aerosol-generating article into the cavity.

[0062] The susceptor element may also include or be a filament susceptor, a mesh susceptor, or a wick susceptor. Similarly, the susceptor element may include or be a susceptor sleeve, a susceptor cup, a cylindrical susceptor, or a tubular susceptor. Preferably, the inner cavity of the susceptor sleeve, susceptor cup, cylindrical susceptor, or tubular susceptor is configured to removably receive at least a portion of the aerosol-forming substrate to be heated or an aerosol-generating article including the aerosol-forming substrate.

[0063] The susceptor elements described above may have any cross-sectional shape, such as, for example, circular, oval, square, rectangular, triangular, or any other suitable shape.

[0064] The term "aerosol-generating device" as used herein generally refers to an electrically operated device capable of interacting with at least one aerosol-forming substrate, particularly an aerosol-forming substrate provided within an aerosol-generating article, to generate an aerosol by heating the substrate. The aerosol-generating device is preferably a smoking 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.

[0065] In addition to the induction coil, the induction heating arrangement may include an alternating current (AC) generator. The AC generator may be powered by a power supply of the aerosol generating device. The AC generator is operably coupled to at least one induction coil. In particular, the at least one 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 changing magnetic field. The AC current may be supplied to the induction coil continuously after activation of the system, or may be supplied intermittently (e.g., with each puff).

[0066] The induction heating arrangement preferably includes a DC / AC converter connected to a DC power supply including an LC network, the LC network comprising a series connection of a capacitor and an induction coil.

[0067] The induction heating arrangement is preferably configured to generate a high frequency varying magnetic field, which as referred to herein may be in the range of 500 kHz (kilohertz) to 30 MHz (megahertz), in particular 5 MHz (megahertz) to 15 MHz (megahertz), preferably 5 MHz (megahertz) to 10 MHz (megahertz).

[0068] The aerosol-generating device may further include 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 arrangement, preferably in a closed-loop configuration, to control the heating of the aerosol-forming substrate to a predetermined operating temperature. The operating temperature used to heat the aerosol-forming substrate may be at least 180°C, particularly at least 300°C, preferably at least 350°C, more preferably at least 370°C, and most preferably at least 400°C. These temperatures are typical operating temperatures for heating but not burning the aerosol-forming substrate. The operating temperature is preferably in the range of 180°C to 370°C, particularly 180°C to 240°C, or 280°C to 370°C. Generally, the operating temperature may depend 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 during use of the system. For example, when the susceptor is configured and arranged to surround the aerosol-forming substrate when the system is in use, the operating temperature may be within a range of 180°C to 240°C. Similarly, when the susceptor is configured and arranged to be disposed within the aerosol-forming substrate when the system is in use, the operating temperature may be within a range of 280°C to 370°C. The above-mentioned operating temperatures preferably refer to the temperature of the susceptor when in use.

[0069] The controller may comprise a microprocessor, e.g., a programmable microprocessor, microcontroller, or application specific integrated circuit chip (ASIC) or other electronic circuitry capable of providing control. The controller may include further electronic components, such as at least one DC / AC inverter and / or power amplifier, e.g., a class C, class D, or class E power amplifier. In particular, the induction heating arrangement may be part of the controller.

[0070] The aerosol generating device may include a power source, particularly a DC power source configured to provide a DC supply voltage and a DC supply current to the induction heating arrangement. The power source is preferably a battery, such as a lithium iron phosphate battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging, i.e., the power source may be rechargeable. The power source may have a capacity that allows for storage of energy sufficient for one or more user experiences. For example, the power source may have a capacity sufficient to allow continuous generation of aerosol for approximately six minutes, or a multiple of six minutes. In another embodiment, the power source may have a capacity sufficient to allow for a predetermined number of puffs or individual activations of the induction heating arrangement.

[0071] The aerosol generating device may comprise a main body that preferably includes at least one of an induction heating arrangement, in particular at least one induction coil, a magnetic flux concentrator, a controller, a power supply, and at least a portion of a cavity.

[0072] In addition to the main body, the aerosol-generating device may further include a mouthpiece, particularly if the aerosol-generating article used with the device does not include a mouthpiece. The mouthpiece may be mounted on the main body of the device. The mouthpiece may be configured to close the receiving cavity when the mouthpiece is attached to the main body. To attach the mouthpiece to the main body, the proximal end portion of the main body may include a magnetic or mechanical mount, such as a bayonet mount or a snap-fit ​​mount, that engages with a corresponding counterpart at the distal end portion of the mouthpiece. If the device does not include a mouthpiece, the aerosol-generating article used with the aerosol-generating device may include a mouthpiece, such as a filter plug.

[0073] The aerosol generating device may comprise at least one air outlet, for example an air outlet in the mouthpiece (if present).

[0074] The aerosol-generating device preferably comprises an air path extending from at least one air inlet, through the receiving cavity, and optionally further to an air outlet, if any, of the mouthpiece. The aerosol-generating device preferably comprises at least one air inlet in fluid communication with the receiving cavity. As a result, the aerosol-generating system may comprise an air path extending from the at least one air inlet into the receiving cavity, and optionally through an aerosol-forming substrate within the article and the mouthpiece, and further into the user's mouth.

[0075] The at least one induction coil and magnetic flux concentrator may be part of an induction module disposed within the device housing and forming at least a portion of the cavity of the device or disposed circumferentially around it, in particular removably disposed therearound.

[0076] In this regard, the present invention also provides an induction module disposable within an aerosol-generating device so as to form or be circumferentially disposed around at least a portion of a cavity of the device, the cavity being configured to removably receive an aerosol-forming substrate to be inductively heated. The induction module includes at least one induction coil for generating a varying magnetic field within the cavity during use, the at least one induction coil being disposed around at least a portion of the receiving cavity when the induction module is disposed in the device. The induction module further includes a magnetic flux concentrator disposed circumferentially around at least a portion of the at least one induction coil and configured to distort the varying magnetic field of the induction coil toward the cavity during use when the induction module is disposed in the device. The magnetic flux concentrator may comprise or be made of a magnetic flux concentrator foil according to the present invention, as described herein. That is, the magnetic flux concentrator foil may be a multilayer magnetic flux concentrator foil having at least one magnetic layer laminated with at least a first support layer, the magnetic layer comprising a plurality of separated pieces of a soft magnetic alloy.

[0077] Further features and advantages of the induction module, particularly the induction coil and magnetic flux concentrator, have been described with respect to the aerosol generating device and apply equally.

[0078] According to another aspect of the present invention, there is also provided an aerosol-generating system comprising an aerosol-generating device according to the present invention and as described herein. The system further comprises an aerosol-generating article for use with the device, the article comprising an aerosol-forming substrate that is inductively heated by the device. The aerosol-generating article is received or receivable at least partially within the cavity of the device.

[0079] 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 as described herein, in which the article and device cooperate to generate a respirable aerosol.

[0080] The term "aerosol-generating article" as used herein 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 also be a consumable product, particularly one that is disposed of after a single use. For example, the article may be a cartridge containing a liquid aerosol-forming substrate that is to be heated. Alternatively, the article may be a rod-shaped article (particularly a tobacco article) that resembles a conventional cigarette.

[0081] As used herein, the term "aerosol-forming substrate" refers to a substrate formed from or including an aerosol-forming material capable of releasing a volatile compound upon heating to form an aerosol. The aerosol-forming substrate is intended to be heated, rather than combusted, to release the aerosol-forming volatile compound. 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. The aerosol-forming substrate 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 may include a non-tobacco material. The aerosol-forming substrate may further include an aerosol former. Examples of suitable aerosol formers are glycerin and propylene glycol. The aerosol-forming substrate may also include other additives and ingredients, such as nicotine or flavoring agents. 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 or adhesive agent, which may include a common aerosol former such as glycerin, which is compressed or molded into a plug.

[0082] As previously mentioned, the at least one susceptor element used to inductively heat the aerosol-forming substrate may be an integral part of the aerosol-generating article rather than being part of the aerosol-generating device. Thus, the aerosol-generating article may comprise at least one susceptor element positioned in thermal proximity or thermal contact with the aerosol-forming substrate such that, in use, the susceptor element can be inductively heated by the inductive heating arrangement when the article is received in a cavity of the device.

[0083] Further features and advantages of the aerosol generating system according to the present invention are described with respect to the aerosol generating device and apply equally.

[0084] According to another aspect of the present invention, there is provided a method for manufacturing a multi-layer magnetic flux concentrator foil for an aerosol generating device according to the present invention and as described herein, the method comprising: - providing a multilayer magnetic flux concentrator foil having at least one magnetic layer of a soft magnetic alloy laminated with at least a first support layer; - cracking at least one magnetic layer into a plurality of pieces by applying an external force to the magnetic flux concentrator foil in a direction transverse to the plane of the foil; - stretching the flux concentrator foil by pulling the flux concentrator foil parallel to the foil plane under a tensile force.

[0085] In particular, stretching the flux concentrator foil by pulling may involve pulling the flux concentrator foil under a tensile force parallel to the foil plane on at least one edge, in particular only on one edge.

[0086] According to the present invention, it has been found that the magnetic layer of a magnetic flux concentrator foil can be easily fragmented into multiple separated pieces by first applying an external force to the magnetic flux concentrator foil transverse to the foil plane and then stretching the magnetic flux concentrator foil parallel to the foil plane, particularly on at least one edge, under a tensile force. The first step leads to the magnetic layer cracking into multiple pieces, and the second step causes the pieces to crack into smaller pieces and, most importantly, to pull apart so that they are separated from each other. Advantageously, the second step leads to a further reduction in the AC resistance of the magnetic layer and, therefore, a further reduction in eddy current losses in the magnetic layer of the magnetic flux concentrator foil due to the pieces being pulled apart.

[0087] Crack-forming the at least one magnetic layer into a plurality of separated fragments can include passing the magnetic flux concentrator foil through at least a pair of rollers, particularly counter-rotating rollers, that apply a compressive force to the passing magnetic flux concentrator foil. That is, pressure is applied to press the rollers against each other so that the passing foil is compressed between the two rollers. At least one of the rollers can include multiple protrusions on its outer surface, each of which locally applies a force to the magnetic flux concentrator foil in a direction transverse to the foil plane. Each of the other rollers acts as a counter-roller. Crack-forming can be enhanced if each of the rollers includes multiple protrusions on its outer surface. The multiple protrusions on both rollers can be formed as complementary protrusions. For example, during operation, the protrusions on one roller can fit between the protrusions on the respective other roller. It is also possible for only one of the rollers to include multiple protrusions, while the respective other roller has a smooth outer surface. A roller with multiple protrusions can be made of metal, such as stainless steel. A roller with a smooth outer surface can be made of rubber. The rubber material should have an appropriate hardness to allow cracking. The magnetic flux concentrator foil may be passed through either a pair of rollers or a series of roller pairs. A bursting pressure in the range of 4 bar to 8 bar, e.g., 6 bar, may be applied to the magnetic flux concentrator foil, particularly via rollers, transverse to the foil plane, to crack the at least one magnetic layer into a plurality of separated fragments. The magnetic flux concentrator foil may be unwound and rewound, respectively, before and after passing through at least one pair of rollers. The unwounding and rewounding of the magnetic flux concentrator foil before and after passing through at least one pair of rollers may occur at a pulling force of 40 to 60 N (Newton), e.g., 50 N (Newton), and a winding speed of 5 to 10 m / min, e.g., 7 m / min.

[0088] The step of cracking the at least one magnetic layer into a plurality of fragments by applying an external force to the magnetic flux concentrator foil transverse to the plane of the foil may be repeated several times, for example, once or twice. Thus, the magnetic flux concentrator foil may pass through the at least one pair of rollers two or three times. Alternatively, the magnetic flux concentrator foil may pass through the at least one pair of rollers only once.

[0089] Pulling the flux concentrator foil only on at least one edge can include pulling the flux concentrator foil back and forth on at least one edge, particularly repeatedly, for example, 4-6 times. Pulling back and forth can enhance pulling the pieces apart.

[0090] Preferably, at least one edge is a sharp edge, i.e. at least one edge may comprise a radius of radius of at most 1 mm, in particular at most 0.3 mm, preferably at most 0.2 mm, more preferably at most 0.15 mm.

[0091] The pulling over the edge may occur under an angle in the range of 60 to 120 degrees, particularly 80 to 100 degrees, preferably 90 degrees, i.e. the flux concentrator foil is bent by that angle as it is pulled over the edge, the angle being measured between a portion of the foil upstream of the edge and a portion of the foil downstream of the edge.

[0092] During pulling of the flux concentrator foil, the pulling force may be in the range of 20 N (Newtons) to 60 N (Newtons), in particular 25 N (Newtons) to 40 N (Newtons), for example 30 N (Newtons). These values ​​have proven to be particularly beneficial for pulling apart pieces. Pulling of the flux concentrator foil over the edges may occur at a speed of 5 to 15 m / min, for example 10 m / min.

[0093] The steps of providing a multi-layer magnetic flux concentrator foil having at least one magnetic layer of a soft magnetic alloy laminated with at least a first support layer include: - providing a ribbon comprising or made of a soft magnetic alloy; - annealing a ribbon comprising or made of a soft magnetic alloy; - providing a first adhesive tape including a first backing layer, the first backing layer being an adhesive; - laminating together a first support layer and (annealed) ribbons comprising or made of a soft magnetic alloy to provide a first stacked arrangement.

[0094] The process of providing a multi-layer magnetic flux concentrator foil comprises the steps of: - repeating the steps of providing a ribbon, annealing the ribbon, providing an (intermediate) adhesive tape comprising an (intermediate) support layer that is an adhesive, and laminating the (intermediate) support layer and the (annealed) ribbon to provide an intermediate laminate arrangement comprising an (intermediate) adhesive tape comprising an intermediate support layer; - providing a second adhesive tape including a second backing layer, the second backing layer being an adhesive; - laminating the first laminate arrangement, the intermediate laminate arrangement, and the second adhesive tape to provide a (non-sealed) multi-layer magnetic flux concentrator foil, wherein the intermediate laminate arrangement is sandwiched between the first laminate arrangement and the second adhesive tape.

[0095] The ribbon containing or made of a soft magnetic alloy may have a thickness in the range of 15 micrometers to 25 micrometers, particularly in the range of 18 micrometers to 23 micrometers, for example, 21 micrometers. The ribbon containing or made of a soft magnetic alloy is preferably provided on a roll or bobbin. Before annealing the ribbon containing or made of a soft magnetic alloy, the ribbon may be rewound, for example, from one bobbin or roll support to another, to adjust the ribbon tension. For example, the ribbon containing or made of a soft magnetic alloy may be rewound in a first step with a tension of 20 Newtons (Newtons) ±10% and in a second step with a tension of 10 Newtons (Newtons) ±10%. The winding speed may be 30 m / min ±10% during the first step and 20 m / min ±10% during the second step.

[0096] The step of annealing the ribbon including or made of the soft magnetic alloy may include heating the ribbon including or made of the soft magnetic alloy to a temperature in the range of, for example, 450°C to 520°C, e.g., 495°C, for a period in the range of 300 minutes to 500 minutes, e.g., 450 minutes.

[0097] The first support layer of the first adhesive tape and the intermediate support layer of the intermediate adhesive tape may comprise an adhesive, particularly a non-PET (polyethylene terephthalate) adhesive. The first support layer and the intermediate support layer may have a thickness in the range of 2 micrometers to 10 micrometers, particularly in the range of 2 micrometers to 5 micrometers, for example, 3 micrometers. In addition to the first / intermediate support layer, the first / intermediate adhesive tape may comprise first and second release films on both sides of the adhesive first / intermediate support layer before attaching the first / intermediate adhesive tape to the (annealed) ribbon. That is, the first and / or second release films are removed before attaching the adhesive first / intermediate support layer to any other object. Thus, the step of laminating the first / intermediate support layer to a ribbon containing or made of a soft magnetic alloy may include removing the first release film from the first / intermediate adhesive tape, attaching the (annealed) ribbon to the adhesive first / intermediate support layer on the side opposite the second release film, and preferably reattaching the first release film onto the (annealed) ribbon containing or made of a soft magnetic alloy. The foregoing steps may be achieved by unwinding the first / intermediate adhesive tape and the (annealed) ribbon, removing the first release film, contacting and attaching the unwound (annealed) ribbon and the unwound adhesive first / intermediate tape (without the first release film) to each other, reattaching the first release film, applying pressure to the resulting first / intermediate laminate arrangement, and optionally unwinding the first / intermediate laminate arrangement. Unwinding of the first / intermediate adhesive tape and (annealed) ribbon may occur at a pulling force of 40-60 N (Newton), e.g., 50 N (Newton), and a winding speed of 5-10 m / min, e.g., 7 m / min. Similarly, unwinding of the first / intermediate laminate arrangement may occur at a pulling force of 40-60 N (Newton), e.g., 50 N (Newton), and a winding speed of 5-10 m / min, e.g., 7 m / min.

[0098] Similarly, the second support layer of the second adhesive tape may comprise a PET (polyethylene terephthalate) adhesive. The second support layer may have a thickness in the range of 2 micrometers to 10 micrometers, particularly in the range of 2 micrometers to 5 micrometers, for example, 3 micrometers. In addition to the second support layer, the second adhesive tape may comprise first and second release films on both sides of the adhesive second support layer before attaching the second adhesive tape to the intermediate laminate arrangement. That is, the first and / or second release films are removed before attaching the adhesive second support layer to any other object. Thus, the step of laminating the second support layer to the intermediate laminate arrangement may comprise removing the second release film from the second adhesive tape and attaching the adhesive second support layer to the intermediate laminate arrangement on the opposing sides of the second release film. The above process can be achieved by unwinding the second adhesive tape, the first laminate arrangement, and the intermediate laminate arrangement, removing the second release film from the second adhesive tape, removing the first and second release films from the intermediate laminate arrangement, and removing the first release film from the first laminate arrangement, contacting and attaching the unwound first laminate arrangement (not including the first release film), the intermediate laminate arrangement (not including the first and second release films), the second adhesive tape (not including the first and second release films), and the second adhesive tape (not including the second release film) together, applying pressure to the resulting (unsealed) multilayer flux concentrator foil, and then unwinding the multilayer flux concentrator foil. Unwinding the second adhesive tape, the first laminate arrangement, and the intermediate laminate arrangement can occur at a pulling force of 40 to 60 Newtons (N), e.g., 50 Newtons (N), and a winding speed of 5 to 10 meters per minute, e.g., 7 meters per minute. Similarly, unwinding the multilayer magnetic flux concentrator foil may occur at a pulling force of 40-60 N (Newtons), for example 50 N (Newtons), and a winding speed of 5-10 m / min, for example 7 m / min.

[0099] The aforementioned process may result in an (unsealed) multi-layer magnetic flux concentrator foil comprising the following layers (from bottom to top): - an adhesive (non-PET) first support layer (from the first lamination arrangement); - a first magnetic layer of the ribbon comprising or made of a soft magnetic alloy (originating from the first lamination arrangement) (annealed); - an adhesive (non-PET) intermediate support layer (from the second lamination arrangement); - a second magnetic layer of the ribbon (annealed) comprising or made of a soft magnetic alloy (from the second lamination arrangement), - a second adhesive (PET-based) support layer (originating from the second lamination arrangement).

[0100] Furthermore, the multilayer magnetic flux concentrator foil may include a first release film on the adhesive second support layer (derived from the second adhesive tape) and a second release film under the adhesive first support layer (derived from the first adhesive tape of the first laminate arrangement). The first release film (derived from the second adhesive tape) and the second release film (derived from the first adhesive tape of the first laminate arrangement) are removed before the multilayer magnetic flux concentrator foil is disposed around at least a portion of the induction coil of an aerosol generating device in which the multilayer magnetic flux concentrator foil is used. Similarly, the first release film (derived from the second adhesive tape) and the second release film (derived from the first adhesive tape of the first laminate arrangement) may be removed before possible further steps of the method described herein, in particular before sealing one or more cut edges of the (unsealed) magnetic flux concentrator, more particularly before attaching adhesive sealing tape to one or each side of the (unsealed) magnetic flux concentrator foil.

[0101] Furthermore, the method may include pulling the flux concentrator foil under tension parallel to the foil plane over at least one roller, particularly a series of rollers, to bend the flux concentrator foil. Advantageously, this step may cause the fragments to crack into smaller fragments, thus further reducing the AC resistance of the magnetic layer. Pulling the flux concentrator foil over at least one roller may be performed before pulling the flux concentrator foil over at least one edge.

[0102] At least one roller may have a radius of at most 50 mm, in particular at most 30 mm, preferably at most 10 mm.

[0103] The pulling force for pulling the magnetic flux concentrator foil over the at least one roller may be in the range of 20N (Newton) to 60N (Newton), in particular 25N (Newton) to 40N (Newton), for example 30N (Newton).

[0104] The method may further include cutting the magnetic flux concentrator foil to size, which may occur before cracking the magnetic layer into the plurality of pieces, before stretching the magnetic flux concentrator foil on at least one edge, or after stretching the magnetic flux concentrator foil on at least one edge.

[0105] The method may further comprise sealing one or more cut edges of the cut-to-size magnetic flux concentrator foil, which advantageously prevents fragments from leaking laterally out of the foil.

[0106] Sealing one or more cut edges of the cut-to-size (non-sealing) multilayer magnetic flux concentrator foil may comprise applying a sealing adhesive tape on one or each side of the cut-to-size magnetic flux concentrator foil, the adhesive sealing tape having a width extension transverse to the opposing cut edges of the magnetic flux concentrator foil that is greater than a width extension of the cut-to-size magnetic flux concentrator foil in the same direction, i.e., transverse to the opposing cut edges of the magnetic flux concentrator foil. As a result, the sealing adhesive tape on each side of the (non-sealing) magnetic flux concentrator foil includes laterally protruding wings that may be in adhesive contact with each other to seal the cut edges of the (non-sealing) magnetic flux concentrator.

[0107] The adhesive sealing tape may include a three-layer adhesive sealing laminate including a PEN (polyethylene terephthalate)-based film sandwiched between a first adhesive layer and a second adhesive layer. Similarly, the adhesive sealing tape may include a three-layer adhesive sealing laminate including a PI (polyimide)-based film sandwiched between a first adhesive layer and a second adhesive layer. The PEN (polyethylene terephthalate)-based film may have a thickness of 2 to 5 micrometers, particularly 3 micrometers. Similarly, the PI (polyimide)-based film may have a thickness of 2 to 8 micrometers, particularly 5 to 7 micrometers. In total, the three-layer adhesive sealing laminate may have a thickness of 3 to 15 micrometers, particularly 4 to 13 micrometers, for example, 5 micrometers, or 7 micrometers, or 9 micrometers, or 13 micrometers. The first and second adhesive layers of the three-layer sealing adhesive tape may include a non-PET (polyethylene terephthalate)-based adhesive. In addition to the three-layer adhesive sealing laminate, the adhesive sealing tape may include a first release film on the first adhesive layer (opposite the PEN-based or PI-based film) and a second release film on the second adhesive layer (opposite the PEN-based or PI-based film), one of the first and second release films being removed before attaching the sealing adhesive tape to the cut-to-size magnetic flux concentrator foil, and the other of the first and second release films being removed before disposing the sealed multi-layer magnetic flux concentrator foil around at least a portion of the induction coil of the aerosol generating device in which the multi-layer magnetic flux concentrator foil is used.

[0108] Similarly, the adhesive sealing tape may include a PET (polyethylene terephthalate) adhesive film. The PET (polyethylene terephthalate) adhesive film may have a thickness of 2 to 5 micrometers, particularly 3 micrometers. In addition to the PET adhesive film, the adhesive sealing tape may include a first release film and a second release film sandwiching the PET (polyethylene terephthalate) adhesive film, one of the first and second release films being removed before attaching the sealing adhesive tape to the cut-to-size magnetic flux concentrator foil, and the other of the first and second release films being removed before disposing the sealed multilayer magnetic flux concentrator foil around at least a portion of the induction coil of the aerosol generating device in which the multilayer magnetic flux concentrator foil is used.

[0109] Thus, the step of attaching the sealing adhesive tape to the cut-to-size multilayer flux concentrator foil may include removing one of the first and second release films from each of the two sealing adhesive tapes and attaching the sealing adhesive tapes to the multilayer flux concentrator foil, one on each side of the multilayer flux concentrator foil. The above steps may include unwinding the two sealing adhesive tapes, removing one of the first and second release films from the sealing adhesive tapes, and, if applicable, removing the first release film (from the second adhesive tape) and the second release film (from the first adhesive tape of the first laminate arrangement). the sealing adhesive tape) from the multilayer magnetic flux concentrator foil; attaching the multilayer magnetic flux concentrator foil (not including the first and second release films) and the unwound sealing adhesive tape (not including one of the first and second release films) together, with one sealing adhesive tape on each side of the multilayer magnetic flux concentrator foil and in contact with each other so that the laterally protruding wings of the sealing adhesive tapes are in adhesive contact with each other; applying pressure to the resulting sealed magnetic flux concentrator foil; and, optionally, unwinding the sealed multilayer magnetic flux concentrator foil.

[0110] The foregoing process may result in a sealed multi-layer magnetic flux concentrator foil that includes the following layers (from bottom to top): - a first three-layer adhesive sealing laminate comprising a (PEN-based or PI-based) film sandwiched between a first adhesive layer and a second adhesive layer; - an adhesive (non-PET) first support layer (originating from the first lamination arrangement); - a first magnetic layer of the ribbon comprising or made of a soft magnetic alloy (originating from the first lamination arrangement) (annealed); - an intermediate support layer (originating from the second lamination arrangement) of adhesive (non-PET based), - a second magnetic layer of the ribbon (annealed) comprising or made of a soft magnetic alloy (from the second lamination arrangement), - a second support layer (originating from a third adhesive tape) of adhesive (PET-based); - A second three-layer adhesive sealing laminate comprising a (PEN-based or PI-based) film sandwiched between a first adhesive layer and a second adhesive layer.

[0111] Similarly, the above process may result in an encapsulated multi-layer magnetic flux concentrator foil that includes the following layers (from bottom to top): a first PET-based adhesive film; - an adhesive (non-PET) first support layer (originating from the first lamination arrangement); - a first magnetic layer of the ribbon comprising or made of a soft magnetic alloy (originating from the first lamination arrangement) (annealed); - an intermediate support layer (originating from the second lamination arrangement) of adhesive (non-PET based), - a second magnetic layer of the ribbon (annealed) comprising or made of a soft magnetic alloy (from the second lamination arrangement), - a second support layer (originating from a third adhesive tape) of adhesive (PET-based); - The second PET adhesive film.

[0112] Furthermore, the sealed multilayer magnetic flux concentrator foil may include a first release film on the second three-layer adhesive sealing laminate or the second PET-based adhesive film, respectively, and a second release film under the first three-layer adhesive sealing laminate or the first PET-based adhesive film, respectively. The first and second release films may be derived from sealing adhesive tapes and may be removed before disposing the sealed multilayer magnetic flux concentrator foil around at least a portion of the induction coil of an aerosol generating device in which the multilayer magnetic flux concentrator foil is used.

[0113] The flux concentrator foil is preferably provided as a flux concentrator tape, in particular a continuous flux concentrator foil, which advantageously allows the method to be implemented as a reel-to-reel process.

[0114] Further features and advantages of the method according to the invention have been described with respect to the aerosol generating device and apply equally.

[0115] The present invention is defined in the claims. However, the following provides a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein.

[0116] Example 1: 1. An aerosol generating apparatus for generating an aerosol by inductively heating an aerosol-forming substrate, comprising: - a device housing comprising a cavity configured to removably receive an aerosol-forming substrate to be heated; - an induction heating arrangement including at least one induction coil for generating a varying magnetic field within the cavity, the induction coil being disposed around at least a portion of the receiving cavity; - A magnetic flux concentrator disposed around at least a portion of an induction coil and configured to distort a changing magnetic field of at least one induction heating arrangement towards a cavity during use of the device, the magnetic flux concentrator including a multilayer magnetic flux concentrator foil having at least one magnetic layer laminated with at least a first support layer, the magnetic layer including a plurality of separated fragments of a soft magnetic alloy, the aerosol generating device comprising: the magnetic flux concentrator. Example 2: The aerosol generating device according to Example 1, wherein the soft magnetic alloy is a nanocrystalline soft magnetic alloy, particularly a nanocrystalline soft magnetic Fe-based alloy. Example 3: The soft magnetic alloy is Fe 100-a-b-c-x-y-z Cu a M b T c Si x Z z and contains a composition of and up to 0.5 atomic% foreign matter, M is one or more of the group consisting of Nb, Mo and Ta, T is one or more of the group consisting of V, Cr, Co and Ni, Z is one or more of the group consisting of C, P and Ge, 0.5 atomic% < a < 1.5 atomic%, 2 atomic% ≤ b < 4 atomic%, 0 atomic% ≤ c < 5 atomic%, 12 atomic% < x < 18 atomic%, 5 atomic% < y < 12 atomic%, and 0 atomic% ≤ z < 2 atomic%, the aerosol generating article according to any one of Examples 1 or 2. Example 4: The soft magnetic alloy is Fe 73.8 Nb3Cu1Si 15.6 B 6.6 and contains a composition of, the aerosol generating article according to any one of Examples 1 to 3. Example 5: Each single fragment has a fragment size of at most 1 millimeter, particularly at most 750 micrometers, or at most 500 micrometers, the aerosol generating device according to any one of Examples 1 to 4. Example 6: The plurality of separated fragments may have an average fragment size of at most 1 millimeter, particularly at most 750 micrometers, or at most 500 micrometers, the aerosol generating device according to any one of Examples 1 to 5. Example 7: An aerosol-generating device according to any one of Examples 1 to 6, wherein the soft magnetic alloy has a specific maximum magnetic permeability of at least 100, in particular at least 1000, preferably at least 10,000, even more preferably at least 50,000. Example 8: An aerosol generating device according to any one of Examples 1 to 7, wherein the plurality of separated fragments are arranged in a pattern including a plurality of crack centers, and the plurality of cracks extend radially outward from each crack center in a web-shaped pattern. Example 9: An aerosol generating device according to any one of Examples 1 to 8, wherein the multi-layer magnetic flux concentrator foil comprises a plurality of adjacent magnetic layers. Example 10: An aerosol generating device according to Example 9, wherein an adhesive film, in particular an electrically insulating adhesive film, is disposed between each pair of adjacent magnetic layers. Example 11: An aerosol generating device according to any one of Examples 1 to 10, wherein the multilayer magnetic flux concentrator foil comprises at least one magnetic layer, or, if applicable, a second support layer facing the first support layer on a side of a plurality of adjacent magnetic layers. Example 12: An aerosol generating device according to any one of Examples 1 to 11, wherein at least one of the first support layer and, if present, the second support layer is one of an adhesive layer, an electrically insulating layer, or an electrically insulating adhesive layer. Example 13: An aerosol generating device according to any one of Examples 1 to 12, wherein the gaps between the multiple separated fragments are at least partially filled with an electrically insulating material, in particular at least one of the material of the first support layer, or, if present, the material of the second support layer, or, if present, the material of the adhesive film between adjacent magnetic layers, or with a matrix material of a soft magnetic alloy. Example 14: 14. An aerosol generating device according to any one of Examples 1 to 13, wherein the flux concentrator foil has a thickness in the range of 0.02 mm to 0.25 mm, in particular 0.05 mm to 0.2 mm, preferably 0.1 mm to 0.15 mm. Example 15: An aerosol generating device according to any one of Examples 1 to 14, wherein a first dielectric wrapper is disposed around at least a portion of the induction coil between the induction coil and the magnetic flux concentrator. Example 16: 16. The aerosol generating apparatus of any one of Examples 1 to 15, wherein the conductive shielding wrapper is disposed around the magnetic flux concentrator. Example 17: 17. An aerosol generating device according to any one of Examples 1 to 16, wherein the second dielectric wrapper is disposed around the magnetic flux concentrator, and in particular around the shielding wrapper, if present. Example 18: An aerosol-generating apparatus according to any one of Examples 1 to 17, further comprising at least one susceptor element disposed at least partially within the cavity. Example 19: 19. The aerosol generating apparatus according to claim 18, wherein the susceptor is a tubular susceptor or a susceptor sleeve. Example 20: An aerosol-generating system comprising an aerosol-generating device according to any one of Examples 1 to 19 and an aerosol-generating article at least partially received or receivable within the cavity of the device, the aerosol-generating article comprising an aerosol-forming substrate that can be heated. Example 21: An aerosol generating system according to Example 20, wherein the aerosol generating article comprises at least one susceptor positioned in thermal proximity or thermal contact with the aerosol-forming substrate such that, when the article is received in the cavity of the device, the susceptor can be inductively heated by the induction heating arrangement during use. Example 22: 22. A method for manufacturing a multi-layer magnetic flux concentrator foil for an aerosol generating device according to any one of Examples 1 to 21, the method comprising: - providing a multilayer magnetic flux concentrator foil having at least one magnetic layer of a soft magnetic alloy laminated with at least a first support layer; - applying an external force to the magnetic flux concentrator foil transverse to the plane of the foil to crack the magnetic layer into a plurality of separated pieces; - stretching the magnetic flux concentrator foil by pulling the magnetic flux concentrator foil under a tensile force parallel to the plane of the foil. Example 23: The method according to example 22, wherein cracking the magnetic layer into a plurality of separated pieces includes passing the magnetic flux concentrator foil through at least a pair of rollers that apply a compressive force on the passing magnetic flux concentrator foil, at least one of the rollers including a plurality of protrusions on its outer surface. Example 24: The method according to example 23, wherein each other roller has a smooth outer surface or each of the rollers includes a plurality of protrusions on its outer surface. Example 25: 26. The method according to any one of Examples 22 to 25, wherein stretching the magnetic flux concentrator foil by pulling comprises pulling the magnetic flux concentrator foil under a tensile force parallel to the foil plane on at least one edge, in particular only on one edge. Example 26: The method according to example 25, wherein pulling the flux concentrator foil only over the at least one edge comprises pulling the flux concentrator foil back and forth over the at least one sharp edge, in particular repeatedly back and forth, preferably 4 to 6 times. Example 27: 27. The method according to any one of embodiments 25 or 26, wherein at least one edge comprises a radius of rounding of at most 1 mm, in particular at most 0.3 mm, preferably at most 0.2 mm, more preferably at most 0.15 mm. Example 28: The method according to any one of Examples 22 to 27, wherein the pulling force is in the range of 20N to 60N, in particular 25N to 40N, for example 30N. Example 29: The method according to any one of examples 22 to 28, further comprising pulling the magnetic flux concentrator foil under a pulling force parallel to the foil plane over at least one roller, particularly a series of rollers, to bend the magnetic flux concentrator foil. Example 30: 30. The process according to embodiment 29, wherein at least one roller has a radius of at most 50 mm, in particular at most 30 mm, preferably at most 10 mm. Example 31: The method according to any one of Examples 29 or 30, wherein the pulling force is in the range of 20N to 60N, in particular 25N to 40N, for example 30N. Example 32: The method according to any one of examples 22 to 31, wherein the flux concentrator foil is provided as a flux concentrator tape. Example 33: The method according to any one of examples 22 to 32, wherein the magnetic flux concentrator foil is provided as a continuous magnetic flux concentrator foil. Example 34: The method according to any one of examples 22-33, further comprising cutting the flux concentrator foil to size. Example 35: 35. The method according to example 34, further comprising sealing one or more cut edges of the cut-to-size magnetic flux concentrator foil. Example 36: The method according to Examples 22 to 35, wherein the method is realized as a reel-to-reel process. [Brief explanation of the drawings]

[0117] The embodiments will now be further described with reference to the following figures:

[0118] [Figure 1] FIG. 1 shows a schematic longitudinal cross-sectional view of an aerosol generation system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a detailed view of the guidance module according to FIG. [Figure 3]3, 4a-4b show details of a multi-layer magnetic flux concentrator foil used in the device according to FIG. [Figure 4] Same as above. [Figure 5] 5-8 show different arrangements of the magnetic flux concentrator foils according to the present invention. [Figure 6] Same as above. [Figure 7] Same as above. [Figure 8] Same as above. [Figure 9] FIG. 9 exemplarily illustrates an exemplary embodiment of a multi-layer magnetic flux concentrator foil including multiple magnetic layers. [Figure 10] FIG. 10 is a detailed view of a guidance module according to a second embodiment of the present invention. [Figure 11] FIG. 11 shows a schematic longitudinal cross-sectional view of an aerosol generation system according to another embodiment of the present invention. [Figure 12] 12 to 15 exemplarily illustrate the various steps of the method according to the invention. [Figure 13] Same as above. [Figure 14] Same as above. [Figure 15] Same as above. [Figure 16] FIG. 16 shows details of another embodiment of a multi-layer flux concentrator foil that can be used in the device according to FIG. 1 and that includes multiple magnetic layers. [Figure 17] FIG. 17 shows a multilayer magnetic flux concentrator foil according to FIG. 16 sealed by a sealing adhesive tape. DETAILED DESCRIPTION OF THE INVENTION

[0119] 1 shows a schematic cross-sectional view of a first exemplary embodiment of an aerosol-generating system 1 according to the present invention. System 1 is configured for generating an aerosol by inductively heating an aerosol-forming substrate 91. System 1 comprises two main components: an aerosol-generating article 90 including the aerosol-forming substrate 91 to be heated, and an aerosol-generating device 10 for use with article 90. Device 10 comprises a receiving cavity 20 for receiving article 90 and an induction heating arrangement for heating the substrate 91 within article 90 when article 90 is inserted into cavity 20.

[0120] The article 90 has a rod shape similar to that of a conventional cigarette. In this embodiment, the article 90 comprises four elements arranged in a coaxial alignment: a substrate element 91, a support element 92, an aerosol cooling element 94, and a filter plug 95. The substrate element is disposed at the distal end of the article 90 and comprises a heated aerosol-forming substrate. The aerosol-forming substrate 91 may comprise, for example, a crimped sheet of homogenized tobacco material containing glycerin as an aerosol former. The support element 92 comprises a hollow core forming a central air passage 93. The filter plug 95 functions as a mouthpiece and may comprise, for example, cellulose acetate fibers. All four elements are substantially cylindrical elements arranged consecutively one after the other. The elements have substantially the same diameter and are surrounded by an outer wrapper 96 made of cigarette paper to form a cylindrical rod. The outer wrapper 96 may be wrapped around the aforementioned elements such that the free ends of the wrapper overlap each other. The wrapper may further include an adhesive that adheres the overlapping free ends of the wrapper to one another.

[0121] The device 10 comprises a substantially rod-shaped main body 11 formed by a substantially cylindrical device housing. Within a distal portion 13, the device 10 comprises a power source 16 (e.g., a lithium-ion battery) and electrical circuitry 17 including a controller for controlling the operation of the device 10, particularly the heating process. Within a proximal portion 14 opposite the distal portion 13, the device 10 comprises a receiving cavity 20. The cavity 20 is open at the proximal end 12 of the device 10, thereby allowing an item 90 to be easily inserted into the receiving cavity 20.

[0122] A bottom portion 21 of the receiving cavity separates the distal portion 13 of the device 10 from the proximal portion 14 of the device 10, and in particular from the receiving cavity 20. The bottom portion is preferably made of a thermally insulating material, such as PEEK (polyetheretherketone). Thus, electrical components within the distal portion 13 can be kept isolated from aerosols or residues generated by the aerosol-generating process within the cavity 20.

[0123] The induction heating arrangement of the apparatus 10 includes an induction source including an induction coil 31 for generating an alternating, particularly high frequency, changing magnetic field. In this embodiment, the induction coil 31 is a helical coil that circumferentially surrounds the cylindrical receiving cavity 20. The induction coil 31 is formed from wire and has multiple turns or windings that extend along the length of the cavity 20. The wire may have any suitable cross-sectional shape, such as square, oval, or triangular. In this embodiment, the wire has a circular cross-section. In other embodiments, the wire may have a flat cross-sectional shape.

[0124] The induction heating arrangement further includes a susceptor element 60 disposed within the receiving cavity 20 so as to experience the changing magnetic field generated by the induction coil 31. In this embodiment, the susceptor element 60 is a susceptor blade 61. At its distal end 64, the susceptor blade is disposed in the bottom portion 21 of the receiving cavity 20 of the apparatus. From there, the susceptor blade 61 extends into the interior void of the receiving cavity 20 toward an opening of the receiving cavity 20 at the proximal end 12 of the apparatus 10. The other end, i.e., the distal free end 63, of the susceptor blade 60 is tapered to allow the susceptor blade to penetrate an aerosol-forming substrate 91 within the distal end portion of the article 90.

[0125] When device 10 is operated, a high-frequency alternating current is passed through induction coil 31. This causes coil 31 to generate a varying magnetic field within cavity 20. As a result, susceptor blade 61 heats due to eddy currents and / or hysteresis losses, depending on the magnetic and electrical properties of the material of susceptor element 60. Susceptor 60 then heats aerosol-forming substrate 91 of article 90 to a temperature sufficient to form an aerosol. The aerosol is drawn downstream through aerosol-generating article 90 and can be inhaled by a user.

[0126] The high frequency varying magnetic field may be in the range of 500 kHz (kilohertz) to 30 MHz (megahertz), in particular 5 MHz (megahertz) to 15 MHz (megahertz), preferably 5 MHz (megahertz) to 10 MHz (megahertz).

[0127] In this embodiment, induction coil 31 is part of induction module 30 that is disposed with proximal portion 14 of aerosol generation device 10. Induction module 30 has a substantially cylindrical shape that is coaxially aligned with central longitudinal axis C of substantially rod-shaped device 10. As can be seen in FIG. 1 , induction module 30 forms at least a portion of cavity 20 or at least a portion of the interior surface of cavity 20.

[0128] 2 shows induction module 30 in more detail. In addition to induction coil 31, induction module 30 includes a tubular inner support sleeve 32 that carries helically wound, cylindrical induction coil 31. At one end, tubular inner support sleeve 32 has an annular projection 34 that extends around the circumference of inner support sleeve 32 to hold coil 31 in place on inner support sleeve 32. Inner support sleeve 32 may be made from any suitable material, such as plastic. In particular, inner support sleeve 32 may cover at least a portion of cavity 20, i.e., at least a portion of the interior surface of cavity 20.

[0129] Both the induction coil 31 and the inner support sleeve 32 (excluding the protrusions 34) extend along the length of the induction coil 3, which may be in the range of 16 to 18 millimeters, and are surrounded by a tubular magnetic flux concentrator 33. The magnetic flux concentrator 33 is configured to distort the changing magnetic field generated by the induction coil 31 toward the cavity 20 during use of the apparatus 10. Essentially, the magnetic flux concentrator 33 acts as a magnetic shield to reduce undesired heating of or interference with external objects. Additionally, the magnetic flux concentrator 33 distorts the magnetic field lines within the internal volume of the induction module 30 such that the density of the magnetic field within the cavity 20 is increased. This may increase the current generated in the susceptor blades 61 located in the cavity 20. In this manner, the electromagnetic field can be concentrated toward the cavity 20, allowing for more efficient heating of the susceptor elements 60.

[0130] In accordance with the present invention, magnetic flux concentrator 33 is fabricated from a multilayer magnetic flux concentrator foil 35. FIG. 3 (not to scale) and FIGS. 4a-4b show respective portions of multilayer magnetic flux concentrator foil 35 in more detail. FIG. 3 is a cross-sectional view through multilayer magnetic flux concentrator foil 35. FIG. 4a is a black-and-white photograph of a portion of a sample of magnetic layer 36. FIG. 4b shows magnetic layer 36 according to FIG. 4a with reversed colors to enhance the visibility of cracks and fragments 39. As shown in FIG. 3, multilayer magnetic flux concentrator foil 35 according to the present invention includes three layers: magnetic layer 36 of a soft magnetic alloy, first support layer 37, and second support layer 38; magnetic layer 36 is laminated between first support layer 37 and second support layer 38. In accordance with the present invention, magnetic layer 36 includes a plurality of separated fragments 39. Due to the fragmentation, the formation of eddy currents within the magnetic layer 36 is partially prevented because the flake-like fragments 39 are separated from one another, thus providing only limited space for eddy currents to form within every single fragment 39. Therefore, compared to a non-fragmented magnetic layer, the fragmented magnetic layer 36 has reduced AC resistance. As a result, when exposed to a changing magnetic field, there is little or no energy dissipation within the fragments 39, and the magnetic flux concentrator foil 35 as a whole heats only slightly, if at all. Therefore, most of the energy provided by the changing magnetic field is dissipated within the susceptor. As shown in FIGS. 4a-4b, the multiple separated fragments 39 may be arranged in a pattern including multiple crack centers, with multiple cracks extending radially outward from each crack center in a web-shaped pattern. As can be seen, the separated fragments each have a different fragment size. The average fragment size may be up to 1 millimeter, particularly up to 500 micrometers.

[0131] The soft magnetic alloy is preferably a nanocrystalline soft magnetic alloy, such as made of Vitroperm 800. Vitroperm 800 has a maximum relative permeability of more than 20,0000 at a magnetic field frequency of 50 Hertz. This material is therefore particularly suitable for concentrating and directing the magnetic field generated by an induction coil. Furthermore, Vitroperm 800 is rather brittle and therefore prone to cracking into multiple fragments.

[0132] The first support layer 37 and the second support layer 38 essentially function to protect the fragile magnetic layer 36, particularly by bonding the fragments 39 of the magnetic layer 36 to the laminate structure, to prevent the fragmented magnetic layer 36 from breaking apart. To that end, the first support layer 37 and the second support layer 38 are preferably adhesive layers. For example, the first support layer 37 and the second support layer 38 may be made of a transparent adhesive or plastic tape. The material of the first support layer 37 and the second support layer 38 is preferably electrically insulating to prevent short-circuiting of the separated fragments 39.

[0133] In this embodiment, magnetic layer 36 may have a layer thickness of 20 micrometers. First support layer 37 and second support layer 38 may each have a layer thickness of 22 micrometers. Thus, magnetic flux concentrator foil 35 may have an overall thickness of 64 micrometers.

[0134] In the embodiment shown in Figures 1 and 2, the magnetic flux concentrator foil 35 is wound with a single winding to form a tubular magnetic flux concentrator or magnetic flux concentrator sleeve with a single winding of the magnetic flux concentrator foil 35 surrounding the induction coil 31. In principle, the magnetic flux concentrator foil 35 may be wound around the induction coil 31 in different ways. According to a first embodiment, as shown in Figure 5, the magnetic flux concentrator foil 35 may be wound with its free ends 351 abutting each other. That is, the longitudinal edges of the magnetic flux concentrator foil 35, which extend along the length axis C of the aerosol generation device 10, abut each other. According to a second embodiment, as shown in Figure 6, the magnetic flux concentrator foil 35 may be wound with its free ends 351 overlapping each other. That is, the longitudinal edges of the magnetic flux concentrator foil 35, which extend along the length axis C of the aerosol generation device 10, abut each other. According to a third embodiment shown in Figure 7, the magnetic flux concentrator foil 35 may be wound with multiple windings to form a tubular magnetic flux concentrator or magnetic flux concentrator sleeve comprising multiple, in particular spiral, windings of the magnetic flux concentrator foil that overlap one another. According to a fourth embodiment shown in Figure 8, the magnetic flux concentrator foil 35, 13 may also be wound helically axially relative to the winding axis, i.e., along the length axis C of the aerosol generation device, to form a tubular magnetic flux concentrator or magnetic flux concentrator sleeve comprising one or more helical windings of the magnetic flux concentrator foil 35, 135.

[0135] FIG. 9 illustrates a second embodiment of a multilayer magnetic flux concentrator foil 235. Compared to the embodiment illustrated in FIGS. 2 and 3, the multilayer magnetic flux concentrator foil 235 according to FIG. 9 includes multiple magnetic layers 236 laminated between a first support layer 237 and a second support layer 238. Furthermore, an electrically insulating adhesive film 270 is disposed between each pair of adjacent magnetic layers 236. Particularly with respect to the multiple winding configurations illustrated in FIGS. 7 and 8, the multiple magnetic layers 236 can limit the number of windings required. Advantageously, this can simplify the manufacture of the magnetic flux concentrator.

[0136] 1 and 2, the flux concentrator foil 35 is wound directly around the induction coil 31 with substantially no radial spacing between the induction coil 31 and the flux concentrator foil 35.

[0137] FIG. 10 shows another embodiment of the induction module 130, in which the magnetic flux concentrator foil 135 is radially spaced from the induction coil 131. That is, the aerosol generating device includes a radial gap 181 between the induction coil 131 and the magnetic flux concentrator foil 135. In this embodiment, the gap 181 is filled with a first dielectric wrapper 182. For example, the induction coil 131 may be wrapped with one or more layers of Kapton tape 182 to fill the radial gap 181 between the induction coil 131 and the magnetic flux concentrator 135. The gap 181 or the first dielectric wrapper 182 may each have a radial extension in the range of 40 micrometers to 240 micrometers, e.g., 80 micrometers. Advantageously, the gap 181 can help reduce losses in the induction coil and increase losses in the heated susceptor, i.e., increase the heating efficiency of the aerosol generating device. Alternatively, the gap may be an air gap. Furthermore, the inductive module 130 according to FIG. 10 includes a conductive shielding wrapper 183 disposed around the magnetic flux concentrator 135 to electrically close the electric field loop and thereby provide additional shielding of the outer portion of the apparatus. For example, the conductive shielding wrapper 180 may be aluminum foil wrapped one or more times around the magnetic flux concentrator 135. Furthermore, the inductive module 130 includes a second dielectric wrapper 185 made of Kapton tape disposed around the magnetic flux concentrator 135 and the shielding wrapper 183 to protect the magnetic flux concentrator 135 and the shielding wrapper 183. Furthermore, in contrast to the embodiment shown in FIGS. 1 and 2, the susceptor element 160 according to the embodiment shown in FIG. 10 is a susceptor sleeve 161 disposed on the inner surface of the inner support sleeve 132 to surround the article when it is received in the receiving cavity. Otherwise, the embodiment shown in FIG. 10 is very similar to the embodiment shown in FIGS. 1 and 2. Accordingly, identical or similar features are designated by the same reference numerals, but incremented by 100.

[0138] FIG. 11 shows a schematic cross-sectional view of yet another embodiment of an aerosol-generating system 1 according to the present invention. The system is identical to the system shown in FIG. 1 , except for the susceptor. Therefore, the same reference numerals are used for the same features. In contrast to the embodiment shown in FIG. 1 , the susceptor 68 of the system according to FIG. 11 is not part of the aerosol-generating device 10, but is part of the aerosol-generating article 90. In this embodiment, the susceptor 68 comprises a susceptor strip 69 made of metal, e.g., stainless steel, located within the aerosol-forming substrate of the base element 91. In particular, the susceptor 68 is disposed within the article 90 such that, after insertion of the article 90 into the cavity 20 of the device 10, the susceptor strip 69 is disposed within the cavity 20, particularly the induction coil 31, and thus experiences the magnetic field of the induction coil 31 during use.

[0139] 12-15 exemplarily illustrate several steps of a method according to the present invention used to manufacture a multilayer magnetic flux concentrator foil for an aerosol generating device according to the present invention. As further described above, the method includes, inter alia, cracking one or more magnetic layers of the multilayer magnetic flux concentrator foil into multiple fragments by applying an external force to the magnetic flux concentrator foil transverse to the foil plane. This can be achieved by passing the magnetic flux concentrator foil through at least a pair of counter-rotating rollers 710, 720 that are pressed against each other so that the passing foil is compressed between the two rollers 710, 720. As shown in FIGS. 12 and 13, at least one of the rollers 710 includes multiple protrusions 711 on its outer surface, each of which locally applies a force to the magnetic flux concentrator foil transverse to the foil plane. In FIG. 12, the upper roller 710 and the lower roller 720 each include multiple protrusions 711, 721 to enhance the cracking effect. Preferably, the plurality of protrusions 711, 721 on both rollers 710, 720 may be formed as complementary protrusions. For example, during operation, the protrusions 711 on the upper roller 710 may fit between the protrusions 721 on the lower roller 720. In contrast, as shown in FIG. 13, it is possible for only one of the rollers 710 to include the plurality of protrusions 711, with the respective other roller 720 including a smooth outer surface that serves as a counter surface for the protrusions 711. For simplicity reasons, FIGS. 12 and 13 show only four rows of protrusions 711, 721 on each roller 710, 720. However, the rollers preferably have more than four rows of protrusions evenly distributed around the circumference of each roller.

[0140] The method further includes pulling the magnetic flux concentrator foil 35 on at least one edge 730 parallel to the foil plane under a pulling force. This is shown in FIG. 14, where arrow 731 indicates the pulling force. This process causes the fragments to crack into smaller fragments and, most importantly, pull further away from each other. Advantageously, this results in a further reduction in the AC resistance of the magnetic layer and, therefore, a further reduction in eddy current losses in the magnetic layer of the magnetic flux concentrator foil. Preferably, at least one edge 730 includes a radius of at most 0.3 mm, particularly at most 0.2 mm, and preferably at most 0.15 mm. Pulling the foil 35 on the edge 730 can occur under an angle 732 ranging from 60 degrees to 120 degrees, for example, 80 degrees, as shown in FIG. 14. The pulling force 731 used to pull the foil 35 over the edge 730 may be in the range 20N to 60N, in particular 25N to 40N, for example 30N.

[0141] Additionally, the method may include pulling the flux concentrator foil 35 parallel to the foil plane under a pulling force 741 over a series of rollers 740 to bend the flux concentrator foil 35, as shown in Figure 15. Advantageously, this step may cause the pieces to crack into smaller pieces, thus resulting in a further reduction in the AC resistance of the magnetic layer. This step may be performed before pulling the flux concentrator foil on at least one edge.

[0142] 16 shows another embodiment (not to scale) of a multi-layer magnetic flux concentrator foil according to the present invention, comprising multiple magnetic layers. From bottom to top, the multi-layer magnetic flux concentrator foil according to FIG. 16 comprises the following layers: - an adhesive (non-PET) first support layer 340; a first magnetic layer 350 comprising or made of a soft magnetic alloy; - an adhesive (non-PET) intermediate support layer 360; a second magnetic layer comprising or made of soft magnetic alloy 370; - an adhesive (PET-based) second support layer 380.

[0143] As explained in more detail above, the multilayer magnetic flux concentrator foil may be sealed to prevent fragments from leaking laterally from the foil. To this end, a sealing adhesive tape 330, 390 may be disposed on one or each side of the (unsealed) magnetic flux concentrator foil according to FIG. 16 . Such a sealed multilayer magnetic flux concentrator foil is shown in FIG. 17 . As can be seen, the adhesive sealing tape 330, 390 has a width extension transverse to the opposing edges of the non-sealing magnetic flux concentrator foil that is greater than the width extension of the non-sealing magnetic flux concentrator foil in the same direction, i.e., transverse to the opposing edges of the (unsealed) magnetic flux concentrator foil. As a result, the sealing adhesive tape 330, 390 on each side of the non-sealing magnetic flux concentrator foil includes laterally protruding wings 335, 395 that may be in adhesive contact with each other to seal the edges of the (unsealed) magnetic flux concentrator. Thus, a specific embodiment of an encapsulated multi-layer magnetic flux concentrator foil according to FIG. 17 would have the following layers (from bottom to top): - a first PET adhesive film 331 (first adhesive sealing tape 330); - an adhesive (non-PET) first support layer 340; a first magnetic layer 350 comprising or made of a soft magnetic alloy; - an adhesive (non-PET) intermediate support layer 360; a second magnetic layer comprising or made of soft magnetic alloy 370; - an adhesive (PET-based) second support layer 380; a second PET-based adhesive film 391 (second adhesive sealing tape 390).

[0144] The first and second PET adhesive films 331, 391 may have a thickness of 2 to 5 micrometers, particularly 3 micrometers. The adhesive (non-PET) first support layer 340, second support layer 360, and adhesive (PET) third support layer 380 may have a thickness of 2 to 10 micrometers, particularly 2 to 5 micrometers, for example 3 micrometers. The first and second magnetic layers 350, 370 may have a thickness of 15 to 25 micrometers, particularly 18 to 23 micrometers, for example 21 micrometers.

[0145] Instead of the first PET-based adhesive film 331 and the second PET-based adhesive film 991, the first sealing tape 330 and the second sealing tape 390 may also include first and second three-layer adhesive sealing laminates, each of which may include a (PEN-based or PI-based) film sandwiched between a first adhesive layer and a second adhesive layer (not shown in FIG. 17).

[0146] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like should be understood in all instances to be modified by the term "about." Also, all ranges include the disclosed maximum and minimum points, including any intermediate ranges therebetween, 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 numerical values ​​that are within the general standard error for the measurement of the property that the number A modifies. In some instances, the number A, as used in the appended claims, may deviate by the percentages recited above, as long as the deviation does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, including any intermediate ranges therebetween, which may or may not be specifically recited herein.

Claims

1. 1. An aerosol generating apparatus for generating an aerosol by inductively heating an aerosol-forming substrate, comprising: a device housing comprising a cavity configured to removably receive the aerosol-forming substrate to be heated; an induction heating arrangement including at least one induction coil for generating a varying magnetic field within the cavity, the induction coil being disposed around at least a portion of the receiving cavity; an aerosol generating device comprising: a magnetic flux concentrator disposed around at least a portion of the induction coil and configured to distort the changing magnetic field of the at least one induction heating arrangement toward the cavity during use of the device, the magnetic flux concentrator comprising a multilayer magnetic flux concentrator foil having at least one magnetic layer laminated with at least a first support layer, the magnetic layer comprising a plurality of separated pieces of a soft magnetic alloy, the plurality of separated pieces being arranged in a pattern including a plurality of crack centers, the plurality of crack centers extending radially outward from the crack center in a web-shaped pattern.

2. 2. The aerosol generating device according to claim 1, wherein the soft magnetic alloy is a metallic glass or a nanocrystalline soft magnetic alloy, in particular a nanocrystalline soft magnetic Fe-based alloy.

3. The soft magnetic alloy is Fe 100-a-b-c-x-y-z Cu a M b T c Si x Z z and a maximum of 0.5 atomic % of foreign matter, wherein M is one or more of the group consisting of Nb, Mo and Ta, T is one or more of the group consisting of V, Cr, Co and Ni, Z is one or more of the group consisting of C, P and Ge, and 0.5 atomic % < a < 1.5 atomic %, 2 atomic % ≤ b < 4 atomic %, 0 atomic % ≤ c < 5 atomic %, 12 atomic % < x < 18 atomic %, 5 atomic % < y < 12 atomic %, and 0 atomic % ≤ z < 2 atomic %.

4. 4. An aerosol generating device according to any one of claims 1 to 3, wherein the multi-layer magnetic flux concentrator foil comprises a plurality of adjacent magnetic layers.

5. 5. The aerosol generating device of claim 1, wherein the multilayer magnetic flux concentrator foil includes a second support layer on a side of the at least one magnetic layer opposite the first support layer.

6. An aerosol generating device as described in claim 4, wherein the multilayer magnetic flux concentrator foil includes a second support layer facing the first support layer on a side of the plurality of adjacent magnetic layers.

7. 7. The aerosol generating device according to claim 1, wherein the first support layer is one of an adhesive layer, an electrically insulating layer, or an electrically insulating adhesive layer.

8. An aerosol generating device as described in claim 5 or 6, wherein the second support layer is one of an adhesive layer, an electrically insulating layer, or an electrically insulating adhesive layer.

9. 9. An aerosol generating device according to any one of claims 1 to 8, wherein gaps between the plurality of separated segments are at least partially filled with an electrically insulating material.

10. 10. An aerosol generating device according to any one of claims 1 to 9, wherein a first dielectric wrapper is disposed around at least a portion of the induction coil between the induction coil and the magnetic flux concentrator.

11. A method for manufacturing a multilayer magnetic flux concentrator foil for an aerosol generating device according to any one of claims 1 to 10, said method comprising: providing a multilayer magnetic flux concentrator foil having at least one magnetic layer of a soft magnetic alloy laminated with at least a first support layer; - cracking the magnetic layer into a plurality of separated pieces by applying an external force to the magnetic flux concentrator foil transverse to the foil plane; stretching the magnetic flux concentrator foil by pulling the magnetic flux concentrator foil parallel to the foil plane under a tensile force.

12. 12. The method of claim 11 , wherein cracking the magnetic layer into a plurality of separated pieces comprises passing the magnetic flux concentrator foil through at least a pair of rollers that apply a compressive force on the passing magnetic flux concentrator foil, at least one of the rollers including a plurality of protrusions on an outer surface thereof.

13. The method of claim 12 , wherein each of the other rollers includes a smooth outer surface, or each of the rollers includes a plurality of protrusions on its outer surface.

14. 14. The method of any one of claims 11 to 13, wherein pulling the magnetic flux concentrator foil comprises pulling the magnetic flux concentrator foil on at least one edge parallel to the foil plane under a tensile force.

15. 15. The method of any one of claims 11 to 14, further comprising pulling the magnetic flux concentrator foil under a pulling force parallel to the foil plane over at least one roller to bend the magnetic flux concentrator foil.

16. The method of any one of claims 11 to 15, further comprising cutting the flux concentrator foil to size.

17. 17. The method of claim 16, further comprising sealing one or more cut edges of the cut-to-size magnetic flux concentrator foil.

Images