RU2792842C2 - Susceptor node for induction heating of aerosol forming substrate - Google Patents

Abstract

FIELD: tobacco industry.

SUBSTANCE: present invention relates to a susceptor node for induction heating of aerosol forming substrate under impact of an alternating magnetic field. The susceptor node contains the first susceptor containing the first susceptor material and the second susceptor containing the second susceptor material. The first and the second susceptor materials are selected in such a way that, during preheating of the susceptor node, starting at a room temperature, a profile of dependence of resistance from temperature of the susceptor node has the minimal resistance value in a temperature range of ±5°C relatively to Curie point of the second susceptor material. The present invention also relates to an induction heating node, an aerosol generating device, and an aerosol generating system, containing such a susceptor node.

EFFECT: obtainment of a susceptor node for heating of aerosol forming substrate.

15 cl, 19 dwg

Description

The present invention relates to a current-collecting (susceptor) assembly for induction heating of an aerosol-forming substrate. The present invention also relates to an induction heating assembly, an aerosol generating device, and an aerosol generating system comprising such a current-collecting (susceptor) assembly.

Aerosol generating systems based on inductive heating of an aerosol-forming substrate that is capable of producing an inhalable aerosol when heated are well known in the art. To heat the aerosol-forming substrate, such systems may comprise an induction heating assembly comprising an induction source and a current collector (susceptor). The induction source is configured to generate an alternating electromagnetic field that induces at least one of heat generating eddy currents or hysteresis losses in the current collector (susceptor). While the induction source is usually part of the aerosol generating device, the current collector (susceptor) may be either part of the device or an integral part of the aerosol generating article that is configured to be placed in the aerosol generating device containing the induction source. In any case, the current collector (susceptor) is located in such a way that it is in thermal proximity or in direct physical contact with the substrate during operation of the system.

To control the substrate temperature, current-collecting (susceptor) assemblies were proposed, containing the first and second current collectors (susceptors) made of different materials. The material of the first pantograph is optimized with respect to heat loss and thus heating efficiency. In contrast, the material of the second current collector is used as a temperature marker. To do this, the material of the second current collector is chosen so that its Curie temperature corresponds to the specified operating temperature of the current collector unit. The magnetic properties of the second pantograph at its Curie temperature change from ferromagnetic or ferrimagnetic to paramagnetic, which is accompanied by a temporary change in its electrical resistance. Thus, by monitoring the corresponding change in the electric current absorbed by the induction source, it is possible to determine when the material of the second current collector reaches its Curie temperature and thus when the desired operating temperature is reached.

However, when tracking the change in electric current absorbed by the induction source, it can be difficult to distinguish between the situation where the material of the second current collector has reached its Curie temperature and the situation where the user is puffing, in particular the initial puff, during which the electric current shows a similar change in characteristic. . The change in electric current during the user's puff is due to the current collector assembly being cooled by air drawn through the aerosol generating article as the user puffs. Cooling affects the temporary change in the electrical resistance of the current collector. This, in turn, causes a corresponding change in the electric current absorbed by the induction source. Typically, cooling of the current collector during a user puff is counteracted by the controller by temporarily increasing the heating power. However, this controller-initiated temporary increase in heating power may have the adverse effect of undesirably overheating the current collector in the event that a monitored change in electric current, which is in fact caused by the material of the second current collector having reached its Curie temperature, is erroneously identified as a consequence of the implementation. tightening by the user.

Therefore, it would be desirable to have a current collector assembly with the advantages of prior art solutions, but without their limitations. In particular, it would be desirable to have a current collector assembly that provides improved temperature control.

The present invention provides a current collector for inductively heating an aerosol-forming substrate under the action of an alternating magnetic field. The current collector assembly contains the first current collector containing the material of the first current collector, and the second current collector containing the material of the second current collector. The materials of the first and second pantographs are chosen so that during the preheating of the pantograph, starting at room temperature, the profile of resistance versus temperature of the pantograph has a minimum resistance value in the temperature range of ±5 degrees Celsius relative to the Curie temperature of the second pantograph material.

According to the present invention, it has been found that the resistance versus temperature profile having such a minimum value is sufficiently distinct from the temporal change in apparent total resistance during puffing by the user. This is due to the fact that the resistance passes through a minimum value during the preheating of the current collector starting at room temperature and therefore in a temperature range below the operating temperature actually used to heat the aerosol-forming substrate. This ensures that the minimum resistance value near the Curie temperature for the second current collector material can be reliably used as a temperature marker to control the heating temperature of the aerosol forming substrate without the risk of misinterpretation as a consequence of user puffing. Accordingly, it is possible to effectively prevent unwanted overheating of the aerosol-forming substrate.

Preferably, the minimum resistance value near the Curie temperature for the material of the second current collector is the absolute minimum of the resistance versus temperature profile.

In the context of this document, the term "starting at room temperature" preferably means that the minimum resistance value near the Curie temperature of the material of the second current collector is reached on the resistance-temperature profile during heating of the current-collector assembly from room temperature in the direction of the operating temperature to which the generatrix is to be heated. aerosol substrate.

In the context of this document, room temperature may correspond to a temperature in the range of 18 degrees Celsius to 25 degrees Celsius, in particular a temperature of 20 degrees Celsius.

Preferably, the material of the second current collector is chosen to have a Curie temperature below 350 degrees Celsius, in particular below 300 degrees Celsius, preferably below 250 degrees Celsius, most preferably below 200 degrees Celsius. These values are well below the typical operating temperatures used to heat the aerosol-generating substrate within the aerosol-generating article. Thus, proper identification of the temperature marker from the minimum of the resistance versus temperature profile near the Curie temperature of the second current collector material is further enhanced by a sufficiently large temperature gap relative to the operating temperature, around which the change in apparent total resistance usually occurs during user puffing.

The operating temperatures used to heat the aerosol-forming substrate within the aerosol-generating article may be at least 300 degrees Celsius, in particular at least 350 degrees Celsius, preferably at least 370 degrees Celsius, most preferably at least 400 degrees Celsius. Celsius. These temperatures are typical operating temperatures for heating, but not burning, the aerosol-forming substrate.

Preferably, the material of the first current collector has a positive temperature coefficient of resistance, while the material of the second current collector preferably has a negative temperature coefficient of resistance. According to the present invention, it has been found that the minimum value in the resistance versus temperature profile of the current collector can be realized by the opposite temperature behavior of the respective electrical resistance of the first and second current collector materials, in addition to the magnetic properties of the second current collector material. Accordingly, when starting the heating of the current collector from room temperature, the resistance of the material of the first current collector increases, while the resistance of the material of the second current collector decreases with increasing temperature. The total apparent resistance of the current collector, "visible" by the induction source, is determined by the combination of the corresponding resistance of the materials of the first and second current collectors. When the Curie temperature of the material of the second current collector is reached from below, the decrease in the resistance of the material of the second current collector usually prevails over the increase in the resistance of the material of the first current collector. Accordingly, the apparent impedance of the current collector assembly decreases in the temperature range below, in particular near and below, the Curie temperature of the material of the second current collector. At the Curie temperature, the material of the second current collector loses its magnetic properties. This leads to an increase in the surface layer available for eddy currents in the material of the second current collector, which is accompanied by a sharp decrease in its resistance. Thus, with a further increase in the temperature of the current collector beyond the Curie temperature of the material of the second current collector, the contribution of the material of the second current collector to the total apparent resistance of the current collector decreases or even becomes negligible. Therefore, after passing through a minimum resistance value near the Curie temperature of the material of the second current collector, the total apparent resistance of the current collector assembly is determined mainly by the increasing resistance of the material of the first current collector. In other words, the total apparent resistance of the current collector increases again. As a result, the current collector assembly has a resistance versus temperature profile that includes a required minimum resistance value near the Curie temperature of the second current collector material.

In the context of this document, the term "current collector" refers to an element that is capable of converting electromagnetic energy into heat under the influence of an alternating electromagnetic field. This may be the result of hysteresis losses and/or eddy currents induced in the current collector, depending on the electrical and magnetic properties of the current collector material. Hysteresis losses occur in ferromagnetic or ferrimagnetic current collectors due to the remagnetization of magnetic domains inside the material under the influence of an alternating electromagnetic field. Eddy currents can be induced if the current collector is electrically conductive. In the case of an electrically conductive ferromagnetic or ferrimagnetic current collector, heat can be generated due to both eddy currents and hysteresis losses.

According to the present invention, the material of the second current collector is at least ferrimagnetic or ferromagnetic and has a specific Curie temperature. The Curie temperature is the temperature above which a ferrimagnetic or ferromagnetic material loses its ferrimagnetism or ferromagnetism, respectively, and becomes paramagnetic. In addition to ferrimagnetism or ferromagnetism, the material of the second current collector may also be electrically conductive.

Preferably, the material of the second current collector may comprise one of mu-metal or permalloy.

While the second current collector is primarily configured to monitor the temperature of the current collector assembly, the first current collector is preferably configured to heat the aerosol-forming substrate. To this end, the first pantograph can be optimized with regard to heat loss and hence heating efficiency. Accordingly, the material of the first current collector may be electrically conductive and/or one of the following: paramagnetic, ferromagnetic, or ferrimagnetic. In case the material of the first current collector is ferromagnetic or ferrimagnetic, the corresponding Curie temperature of the material of the first current collector is preferably different from the Curie temperature of the material of the second current collector, in particular it is higher than any of the aforementioned typical operating temperatures used to heat the aerosol forming substrate. For example, the material of the first current collector may have a Curie temperature of at least 400 degrees Celsius, in particular at least 500 degrees Celsius, preferably at least 600 degrees Celsius.

For example, the material of the first current collector may comprise one of the following: aluminum, iron, nickel, copper, bronze, cobalt, carbon steel, stainless steel, ferritic stainless steel, martensitic stainless steel, or austenitic stainless steel.

Preferably, the first current collector and the second current collector are in close physical contact with each other. In particular, the first and second current collectors may form a single current collector assembly. Thus, the first and second current collectors have substantially the same temperature when heated. This ensures high accuracy of temperature control of the first pantograph using the second pantograph. Close contact between the first current collector and the second current collector may be realized by any suitable means. For example, the second current collector may be formed on the first current collector by galvanization, deposition, coating, cladding, or welding. Preferred methods include electroplating (electroplating), cladding, dip plating, or roll plating.

The current-collecting assembly according to the present invention can preferably be configured to be activated by an alternating field, in particular a high-frequency electromagnetic field. As noted herein, the high frequency electromagnetic field may have a frequency 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).

Each of the first pantograph and the second pantograph or pantograph assembly may have a variety of geometric configurations. At least one of the first pantograph, the second pantograph, or the pantograph assembly may be one of the following: a particulate pantograph, or a current-collecting filament, or a current-collecting mesh, or a current-collecting wick, or a current-collecting pin, or a current-collecting rod, or a current-collecting plate, or a current-collecting strip, or a current-collecting sleeve, or a current-collecting cup, or a cylindrical current-collector, or a flat current-collector.

For example, at least one of the first pantograph, the second pantograph, or the pantograph assembly may be one of the following: a filamentous pantograph, or a mesh pantograph, or a wick pantograph. Such current collectors can be advantageous in terms of their fabrication, geometric ordering and reproducibility, as well as their wick function. Geometrical order and reproducibility can provide an advantage in both temperature control and controlled localized heating. The capillary function may be useful when used with a liquid aerosol-forming substrate. When used, any of these current collectors may be in direct physical contact with the aerosol-forming substrate to be heated. For example, the first and/or second filamentous current collectors may be embedded within the aerosol-forming substrate of the aerosol-generating article. Similarly, the first and/or second current collectors may be a mesh current collector or a wick current collector, either as part of an aerosol generating article, which preferably contains a liquid aerosol generating substrate, or as part of an aerosol generating device. In the latter configuration, the device may comprise a reservoir for a liquid aerosol-forming substrate. Alternatively, the device may be configured to accommodate an aerosol generating article, in particular a cartridge that contains a liquid aerosol-forming substrate and which is configured to interact with a filamentary current collector or mesh current collector or wick current collector of the aerosol generating device.

At least one of the first pantograph, the second pantograph, or the current collector assembly may be a current collector plate or a current collector rod or a current collector pin. Preferably, the first current collector and the second current collector together form a current collector plate or a current collector rod or a current collector pin. For example, one of the first or second current collectors may form the core or inner layer of the current collector plate or current collector bar or current collector pin, while the corresponding other of the first or second current collectors may form the jacket or shell of the current collector plate or current collector rod or current collector pin.

As a current collector plate or a current collector rod or a current collector pin, at least one of the first current collector, the second current collector or the current collector assembly may be part of the aerosol generating article, in particular it may be located inside the aerosol generating substrate of the aerosol generating article. One extreme end of the current collector plate or current collector rod or current collector pin may be tapered or pointed to facilitate insertion of the current collector plate or current collector rod or current collector pin into the aerosol-forming substrate of the article.

Alternatively, at least one of the first current collector, second current collector, or current collector assembly, each in the form of a current collector plate, current collector rod, or current collector pin, may be part of an aerosol generating device. With one of its ends, in particular the distal end, the current-collecting plate or the current-collecting rod or the current-collecting pin can be located in the lower part of the receiving cavity of the device, in particular attached to it. From here, the current-collecting plate or the current-collecting rod or the current-collecting pin preferably extends into the interior of the receiving cavity towards the opening of the receiving cavity. The receiving cavity opening is preferably located at the proximal end of the aerosol generating device. The other end, i.e. the far free end of the current collector plate or the current collector rod or the current collector pin, may be tapered or pointed so as to allow the current collector plate or the current collector rod or the current collector pin to easily penetrate into the aerosol-forming substrate to be heated, for example into the aerosol-forming substrate. located at the far end portion of the aerosol generating article.

In each case, the current collector plate or the current collector rod or the current collector pin may have a length in the range of 8 mm (millimeters) to 16 mm (millimeters), in particular 10 mm (millimeters) to 14 mm (millimeters), preferably 12 mm (millimeters). ). In the case of a current collector plate, the first current collector and/or the second current collector, in particular the current collector unit, may have a width, for example, in the range from 2 mm (millimeters) to 6 mm (millimeters), in particular from 4 mm (millimeters) to 5 mm ( millimeters). Similarly, the thickness of the plate-like first current collector and/or the second current collector, in particular the plate-like current collector assembly, preferably ranges from 0.03 mm (millimeter) to 0.15 mm (millimeter), more preferably from 0.05 mm (millimeter) up to 0.09 mm (millimeter).

At least one of the first current collector, the second current collector or the current collector assembly may be a cylindrical current collector or a current collector sleeve or a current collector cup. The cylindrical current collector or the current collector sleeve or the current collector cup may form a receptacle, or they may be arranged circumferentially around the receptacle of an aerosol generating device, of which the current collector assembly or at least one of the first or second current collectors may be a part. In this configuration, the first and/or second current collector or current collector assembly forms an induction heating furnace or heating chamber configured to receive an aerosol-forming substrate to be heated therein. Alternatively, at least one of the first current collector, the second current collector, or the current collector assembly, each in the form of a cylindrical current collector or a current collector sleeve or a current collector cup, may surround at least a portion of the aerosol-forming substrate to be heated, thereby forming a heating furnace or heating chamber. . In particular, each of them may form at least a portion of the shell, wrapper, body or casing of the aerosol generating article.

The current collector assembly may be a multilayer current collector assembly. In this regard, the first current collector and the second current collector can form layers, in particular adjacent layers, of a multilayer current collector assembly.

In a multilayer current collector assembly, the first current collector and the second current collector may be in close physical contact with each other. This ensures that the temperature of the first pantograph is controlled sufficiently precisely by the second pantograph, since the first and second pantographs have essentially the same temperature.

The second current collector may be applied to the first current collector by galvanization, deposition, coating, cladding, or welding. Preferably, the second current collector is applied to the first current collector by spraying, dip coating, roll coating, electroplating or cladding.

Preferably, the second current collector is present as a dense layer. The dense layer has a higher magnetic permeability than the porous layer, making it easier to detect subtle changes at the Curie temperature.

The individual layers of the multilayer susceptor assembly may be exposed or exposed to the environment on the circumferential outer surface of the multilayer susceptor assembly when viewed in any direction parallel and/or transverse to said layers. Alternatively, the multilayer current collector assembly may be coated with a protective coating.

The multilayer susceptor assembly can be used to implement other geometries of the susceptor assembly.

For example, the multilayer current collector assembly may be an elongated current collector strip or a current collector plate having a length in the range of 8 mm (millimeters) to 16 mm (millimeters), in particular from 10 mm (millimeters) to 14 mm (millimeters), preferably 12 mm (millimeters). The width of the current collector can be, for example, in the range from 2 mm (millimeters) to 6 mm (millimeters), in particular from 4 mm (millimeters) to 5 mm (millimeters). The thickness of the current collector is preferably in the range of 0.03 mm (millimeter) to 0.15 mm (millimeter), more preferably 0.05 mm (millimeter) to 0.09 mm (millimeter). The multilayer current collector plate may have a free tapered end.

For example, the multi-layer current collector assembly may be an elongated strip having a first current collector that is a 430 stainless steel strip having a length of 12 mm (millimeters), a width of 4 mm (millimeters) to 5 mm (millimeters), such as 4 mm (millimeter), and a thickness of approximately 50 µm (micrometers). 430 stainless steel can be coated with a layer of mu-metal or permalloy as a second current collector having a thickness of 5 microns (micrometers) to 30 microns (micrometers), for example 10 microns (micrometers).

The term "thickness" is used herein to refer to dimensions extending between the top and bottom sides, such as between the top side and bottom side of a layer, or the top side and bottom side of a multilayer current collector assembly. The term "width" is used in this document to refer to the dimensions extending between two opposite sides. The term "length" is used herein to refer to dimensions extending between the front and back sides, or between other two opposite sides, perpendicular to two opposite sides defining the width. Thickness, width and length can be perpendicular to each other.

Similarly, the multi-layer current-collecting assembly may be a multi-layer current-collecting rod or a multi-layer current-collecting pin, particularly as described above. In this configuration, one of the first or second current collectors may form a core that is surrounded by a surrounding layer formed by the corresponding other of the first or second current collectors. Preferably, it is the first current collector that forms the surrounding layer in case the first current collector is optimized for heating the substrate. In this way, heat transfer to the surrounding aerosol-forming substrate is improved.

Alternatively, the multi-layer current collector assembly can be a multi-layer current collector sleeve or a multi-layer current collector cup or a cylindrical multi-layer current collector, in particular as described above. One of the first or second current collectors may form the inner wall of the multilayer current collector sleeve, the multilayer current collector cup, or the cylindrical multilayer current collector. A corresponding other of the first or second current collectors may form the outer wall of the multilayer current collector sleeve, the multilayer current collector cup or the cylindrical multilayer current collector. Preferably, the first current collector forms an inner wall, in particular if the first current collector is optimized for heating the substrate. As described above, a multilayer current collector sleeve or a multilayer current collector cup or a cylindrical multilayer current collector may surround at least a portion of the aerosol generating substrate to be heated, in particular they may form at least a portion of a sheath, wrapper, casing or body of the aerosol generating article. Alternatively, a multi-layer current collector sleeve or a multi-layer current collector cup or a cylindrical multi-layer current collector may form a receiving cavity, or they may be located circumferentially around the receiving cavity of an aerosol-generating device, of which said current-collecting assembly or at least one of the first or second pantographs.

It may be desirable, for example, for the purpose of manufacturing an aerosol generating article, that the first and second current collectors have similar geometries, such as those described above.

Alternatively, the first pantograph and the second pantograph may have different geometries. Thus, the first and second pantographs can be adapted for their particular function. The first current collector, preferably having a heating function, may have a geometric configuration that provides a large surface area for the aerosol-forming substrate to improve heat transfer. In contrast, the second pantograph, which preferably has a temperature control function, does not need a very large surface area. If the material of the first current collector is optimized for heating the substrate, then it may be preferable that the volume of material of the second current collector does not exceed the volume necessary to provide a detectable Curie point.

According to this aspect, the second current collector may include one or more second current collector elements. Preferably, said one or more second current collectors are significantly smaller than the first current collector, i.e. their volume is less than that of the first current collector. Each of said one or more second current collectors may be in close physical contact with the first current collector. Due to this, the first and second pantographs have essentially the same temperature, which improves the accuracy of temperature control of the first pantograph by means of the second pantograph, which acts as a temperature marker.

For example, the first current collector may be in the form of a current collector plate, or a current collector strip, or a current collector sleeve, or a current collector cup, while the second current collector material may be in the form of separate spacers that are applied to the first current collector material by galvanization, deposition, or welding.

According to another example, the first susceptor may be a strip susceptor or a filamentary susceptor or a mesh susceptor while the second susceptor is a particulate susceptor. Both the first current collector in the form of filaments or mesh and the second current collector in the form of particles can, for example, be integrated into the aerosol-generating article and be in direct physical contact with the aerosol-generating substrate to be heated. In this particular configuration, the first current collector may extend within the aerosol-generating substrate through the center of the aerosol-generating article, while the second current collector may be uniformly distributed throughout the aerosol-generating substrate.

The first and second current collectors need not be in close physical contact with each other. The first current collector may be a current collector plate, which is a heating plate for penetrating the aerosol-forming substrate to be heated. Similarly, the first current collector may be a current-collecting sleeve or a current-collecting assembly forming a heating furnace or heating chamber. In either of these configurations, the second pantograph may be located elsewhere within the heating assembly, spaced apart from, but still in thermal proximity to, the first pantograph.

The first and second current collectors may form different parts of the current collector assembly. For example, the first current collector may form a side wall portion or sleeve portion of the cup current collector assembly, while the second current collector forms the bottom of the cup current collector assembly.

At least a portion of at least one of the first current collector and the second current collector may comprise a protective cover. Similarly, at least a portion of the current collector assembly may include a protective cover. The protective cover may be made of glass, ceramic or an inert metal formed or coated over at least a portion of the first current collector and/or the second current collector or current collector assembly, respectively. Preferably, the protective cover may be configured to at least one of the following: prevent adhesion of the aerosol-forming substrate to the surface of the current collector, prevent diffusion of material, such as metal diffusion, from the current-collector material into the aerosol-forming substrate, and improve the mechanical rigidity of the current collector assembly. Preferably, the protective cover is non-conductive.

The present invention also provides an aerosol-generating article comprising, for example, an aerosol-generating substrate and a current-collecting assembly according to the present invention, as described herein, wherein the current-collecting assembly is configured to inductively heat the aerosol-generating substrate under the action of an alternating magnetic field.

In the context of this document, the term "aerosol-generating article" refers to an article containing at least one aerosol-forming substrate, which, when heated, releases volatile compounds capable of forming an aerosol. Preferably, the aerosol generating article is a heated aerosol generating article. In other words, the aerosol-generating article preferably contains at least one aerosol-forming substrate intended to be heated rather than combusted in order to release volatile compounds that are capable of forming an aerosol. The aerosol generating article may be a consumable part, in particular a consumable part to be disposed of after a single use. The aerosol generating product may be a tobacco product. For example, the article may be a cartridge containing a liquid or solid aerosol-forming substrate to be heated. Alternatively, the product may be a rod-shaped product, in particular a tobacco product similar to conventional cigarettes and containing a solid aerosol-forming substrate.

Preferably, the aerosol generating article has a circular or elliptical or oval or square or rectangular or triangular or polygonal section.

In addition to the aerosol-forming substrate and current collector assembly, the article may also contain other elements.

In particular, the article may comprise a mouthpiece. In the context of this document, the term "mouthpiece" means the part of the product that is placed in the user's mouth for the purpose of directly inhaling the aerosol from the product. Preferably, the mouthpiece contains a filter.

In addition, the article may include a casing, in particular a tubular wrapper, surrounding at least a portion of the aerosol-forming substrate. The wrapper may include a current collector. This provides the advantage of being able to uniformly and symmetrically heat the aerosol-forming substrate surrounded by the current collector assembly.

In particular, with regard to an aerosol-generating article that is a rod-shaped article similar to conventional cigarettes and/or containing a solid aerosol-forming substrate, the article may further comprise: a support member having a central air path, an aerosol cooling member, and a filter member. The filter element preferably serves as a mouthpiece. In particular, the article may comprise a substrate element that contains an aerosol-forming substrate and a current-collecting assembly in contact with the aerosol-forming substrate. Any of these elements, or any combination thereof, may be arranged in series with respect to the aerosol-forming rod segment. Preferably, the substrate element is located at the distal end of the product. Likewise, the filter element is preferably located at the proximal end of the article. In addition, these elements may have the same outer section as the rod segment forming the aerosol.

In addition, the article may include a casing or wrapper surrounding at least a portion of the aerosol-forming substrate. In particular, the article may comprise a wrapper surrounding at least a portion of the various segments and elements mentioned above in such a manner as to hold them together and retain the desired sectional shape of the article.

The casing or wrapper may include at least the first current collector or both of the first and second current collectors of the current collector assembly. This provides the advantage of being able to uniformly and symmetrically heat the aerosol-forming substrate surrounded by the first current collector or current collector assembly.

Preferably, the casing or wrapper forms at least a portion of the outer surface of the article. The casing may form a cartridge containing a reservoir that contains an aerosol-forming substrate, such as a liquid aerosol-forming substrate. The wrapper may be a paper wrapper, in particular a paper wrapper made from cigarette paper. Alternatively, the wrapper may be a foil, for example made from plastic. The wrapper may be fluid-permeable so that a volatilized aerosol-forming substrate can be released from the article or air can be drawn into the article through its circumferential surface. In addition, the wrapper may contain at least one volatile substance to be activated and released from the wrapper when heated. For example, the wrapper may be impregnated with an aromatic volatile substance.

Additional features and advantages of the aerosol generating article according to the present invention have been described in relation to the current collector assembly and will not be described again.

The present invention also provides an induction heating unit configured to inductively heat an aerosol-forming substrate to a predetermined operating temperature. The heating assembly comprises an induction source configured to generate an alternating electromagnetic field, as well as a current-collecting assembly according to the present invention described herein, wherein the current-collecting assembly is configured to inductively heat the aerosol-forming substrate under the action of an alternating magnetic field generated by the induction source.

To generate an alternating electromagnetic field, the induction source may comprise at least one inductor, preferably at least one inductor.

The induction source may comprise a single inductor or a plurality of inductors. The number of inductors may depend on the number of current collectors and/or the size and shape of the current collector assembly. The coil or coils may be shaped to match the shape of the first and/or second current collector or current collector assembly, respectively. Similarly, the coil or coils or coils may be shaped to match the shape of the housing of the aerosol generating device, of which the heating assembly may be a part.

Said at least one inductor may be a helical coil or a flat planar coil, in particular a disk coil or a curved planar coil. The use of a flat helical coil allows a compact design that is reliable and inexpensive to manufacture. The use of a helical inductor provides the advantage of being able to generate a uniform alternating electromagnetic field. In the context of this document, the term "flat helical coil" means a coil that is generally planar coil and the winding axis of which is located normal to the plane in which the coil lies. A flat helical inductor can be of any desired shape in the plane of the coil. For example, a flat helical coil may be circular in shape, or it may be generally oblong or rectangular in shape. However, the term "flat helical coil" in this document covers both coils that are planar and flat helical coils whose shape conforms to a curved surface. For example, the inductor may be a "curvilinear" planar coil located around the circumference of a preferably cylindrical coil support, such as a ferrite core. flat spiral coil.

The first and/or the second inductor may be contained within one of the following: a casing of a heating assembly or a main body or casing of an aerosol generating device that contains said heating assembly. The first and/or the second inductor may be wound around a preferably cylindrical coil support, such as a ferrite core.

The induction source may comprise an alternating current (AC) generator. The alternator may be powered by a power source of the aerosol generating device. The alternator is operatively connected to said at least one inductor. In particular, said at least one inductor may be an integral part of the alternator. The alternator is configured to generate a high frequency oscillatory current passed through said at least one inductor to generate an alternating electromagnetic field. The alternating current may be applied to said at least one inductor continuously after activation of the system, or it may be applied intermittently, for example from puff to puff.

Preferably, the induction source comprises a DC/AC converter connected to a DC power supply comprising an LC circuit having a capacitor and an inductor connected in series.

The induction source is preferably configured to generate a high frequency electromagnetic field. As stated in this document, the high frequency electromagnetic field can range from 500 kHz (kilohertz) to 30 MHz (megahertz), in particular from 5 MHz (megahertz) to 15 MHz (megahertz), preferably from 5 MHz (megahertz) to 10 MHz (megahertz).

The heating unit may also include a controller configured to control the operation of the heating unit. In particular, the controller may be configured to control the operation of the induction source, preferably in a closed loop configuration, to control the heating of the aerosol-forming substrate to a predetermined operating temperature. As mentioned above, the operating temperature used to heat the aerosol-forming substrate may be at least 300 degrees Celsius, in particular at least 350 degrees Celsius, preferably at least 370 degrees Celsius, most preferably at least 400 degrees. Celsius. These temperatures are typical operating temperatures for heating, but not burning, the aerosol-forming substrate.

The controller may comprise a microprocessor, such as a programmable microprocessor, microcontroller, or application specific integrated circuit (ASIC), or other electronic circuit capable of providing control. The controller may include additional electronic components such as at least one DC/AC converter and/or power amplifiers, such as a class D or class E power amplifier. In particular, the induction source may be part of the controller.

The controller may be the entire controller or part of the controller of the aerosol generating device of which the heating assembly according to the present invention is a part.

The controller may be configured to determine, during preheating of the current collector assembly from room temperature towards operating temperature, the minimum apparent impedance value achievable in a temperature range of ±5 degrees Celsius relative to the Curie temperature of the second current collector material. This provides the advantage of being able to correctly identify a temperature marker near the Curie temperature of the second current collector material. To do this, the controller may be generally configured to determine, based on the supply voltage, in particular the DC supply voltage supplied from the power supply, the actual apparent resistance of the current collector, which in turn is indicative of the actual temperature of the current collector.

In addition, the controller may be configured to control the operation of the induction source in a closed loop configuration such that the actual apparent resistivity corresponds to the sum of the determined apparent resistivity value and the predetermined apparent resistivity offset value to control the heating of the aerosol-forming substrate to the operating temperature. In this aspect, heating temperature control is preferably based on the principles of clamping the bias or bias control using a predetermined apparent resistivity bias to level the gap between the apparent resistivity measured at the marker temperature and the apparent resistivity at operating temperature. This provides the advantage of avoiding direct control of the heating temperature based on a predetermined target value of apparent resistance at operating temperature and thus avoiding misinterpretation of the measured resistance value. In addition, heating temperature offset control is more stable and reliable than temperature control based on measured absolute values of apparent resistivity at the desired operating temperature. This is due to the fact that the measured absolute value of the apparent resistance, determined on the basis of the supply voltage and supply current, depends on various factors such as, for example, the resistance of the electrical circuit of the induction source and various contact resistances. Such factors are influenced by the environment and may change over time and/or between different induction sources and current collectors of the same type, depending on the manufacturing process. Such effects provide the advantage of essentially leveling out the value of the difference between two measured absolute values of the apparent resistivity. Accordingly, the use of the apparent resistivity offset value for temperature control is less susceptible to these negative effects and changes.

The apparent resistivity shift amount for controlling the heating temperature of the aerosol-forming substrate to the operating temperature can be predetermined by means of a calibration measurement, for example, during the manufacture of the device.

Preferably, the minimum value near the Curie temperature of the material of the second current collector is the absolute minimum of the resistance versus temperature profile.

In the context of this document, the expression "starting at room temperature" preferably means that the minimum resistance value near the Curie temperature of the material of the second current collector is reached on the resistance-temperature profile during preheating, i.e. heating of the current collector assembly from room temperature towards the operating temperature, up to which the aerosol-forming substrate is to be heated.

In the context of this document, room temperature may correspond to a temperature in the range of 18 degrees Celsius to 25 degrees Celsius, in particular a temperature of 20 degrees Celsius.

The controller and at least part of the induction source, in particular an induction source other than an inductor, may be located on a common printed circuit board. This is especially useful when applied to a compact design.

In order to determine the actual apparent resistance of the current collector, which indicates the actual temperature of the current collector, the controller of the heating node may comprise at least one of a voltage sensor, in particular a DC voltage sensor, for measuring the supply voltage, in particular the DC voltage supplied from the power supply. , or a current sensor, in particular a DC current sensor, for measuring the supply current, in particular the DC supply supplied from the power supply.

The heating unit may comprise a power source, in particular a DC power source configured to supply a DC supply voltage and a DC supply to the induction source. Preferably, the power source is a battery such as a lithium iron phosphate battery. Alternatively, the power supply may be another type of charge storage device, such as a capacitor. The power supply may need to be recharged, that is, the power supply may be rechargeable. The power supply may have a capacity that allows sufficient energy to be stored for one or more user consumption sessions. For example, the power supply may have a capacity sufficient to enable continuous generation of the aerosol for a period of approximately six minutes, or for a period in multiples of six minutes. In yet another example, the power source may have sufficient capacity to allow a given number of puffs or individual activations of the induction source. The power source may be a common power source for the aerosol generating device of which the heating assembly according to the present invention is a part.

The determined operating temperature may be at least 300 degrees Celsius, in particular at least 350 degrees Celsius, preferably at least 370 degrees Celsius, most preferably at least 400 degrees Celsius. These temperatures are typical operating temperatures for heating, but not burning, the aerosol-forming substrate.

Preferably, the second current collector comprises a second current collector material having a Curie temperature at least 20 degrees Celsius below the operating temperature of the heating assembly. Preferably, a temperature gap of at least 20 degrees between the Curie temperature of the second current collector material and the operating temperature of the heating assembly is large enough to reliably use the Curie temperature of the second current collector material as a temperature marker to control the heating temperature of the aerosol-forming substrate without the risk of misinterpretation as a consequence of puffing. user. However, the specified temperature range can be even larger. Accordingly, the material of the second current collector may have a Curie temperature of at least 50 degrees Celsius, in particular at least 100 degrees Celsius, preferably at least 150 degrees Celsius, most preferably at least 200 degrees Celsius below operating temperature. Increasing the temperature gap between the Curie temperature of the second current collector material and the operating temperature of the heating unit provides the advantage of improving the proper identification of the temperature marker and thus the reliability of the temperature control.

According to this aspect, the material of the second current collector is preferably chosen such that it has a Curie temperature below 350 degrees Celsius, in particular below 300 degrees Celsius, preferably below 250 degrees Celsius, most preferably below 200 degrees Celsius. These values are well below the typical operating temperatures used to heat the aerosol-forming substrate. This ensures proper identification of the temperature marker.

Additional features and advantages of the heating assembly according to the present invention have been described in relation to the current collector assembly and will not be described again.

The present invention also provides an aerosol generating device for generating an aerosol by heating an aerosol-forming substrate. The device comprises a receiving cavity for receiving an aerosol-forming substrate to be heated. The device also includes an induction heating assembly according to the present invention described herein for induction heating of an aerosol-forming substrate within a receiving cavity.

In the context of this document, the term "aerosol-generating device" is used to describe an electrical device that is capable of interacting with at least one aerosol-generating substrate, in particular, with an aerosol-generating substrate provided within an aerosol-generating article, so as to generate an aerosol by heating specified substrate. Preferably, the aerosol generating device is an inhalation device for generating an aerosol directly inhaled by the user through the mouth. Specifically, the aerosol generating device is a portable aerosol generating device.

In the context of this document, the term "aerosol-forming substrate" means a substrate capable of releasing volatile compounds that can form an aerosol when the aerosol-forming substrate is heated. The aerosol-generating substrate is part of the aerosol-generating article. The aerosol-forming substrate may be a solid or, preferably, a liquid aerosol-forming substrate. In both cases, the aerosol-forming substrate may contain at least one of the solid or liquid components. The aerosol-forming substrate may comprise 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 comprise a non-tobacco material. The aerosol-forming substrate may also contain an aerosol-forming agent. Examples of suitable aerosol forming agents are glycerin and propylene glycol. The aerosol-forming substrate may also contain other additives and ingredients such as nicotine or flavors. The aerosol-forming substrate may also be a pasty material, a pouch of porous material containing an aerosol-forming substrate, or, for example, loose tobacco mixed with a gelling agent or adhesive, which may contain a conventional aerosolizing agent such as glycerin, and which pressed or molded in the form of a plug.

The receiving cavity may be built into the housing of the aerosol generating device.

As described above, the aerosol generating device may include a common controller to control the operation of the device. The common controller may or may include a heating unit controller.

As further described above, the aerosol generating device may also comprise a power source, in particular a DC power source such as a battery. In particular, the power supply may be an aerosol generating device power supply that is used, among other things, to supply a DC supply voltage and a DC supply to the induction source of the heating unit.

The aerosol generating device may include a main body which preferably contains at least one induction source, at least one inductor, a controller, a power source, and at least a portion of the receiving cavity.

In addition to the main body, the aerosol generating device may also include a mouthpiece, in particular if the aerosol generating article for use with the device does not include a mouthpiece. The mouthpiece can be mounted on the main body of the device. In particular, the mouthpiece may be configured to close the receiving chamber when the mouthpiece is mounted on 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 fastener, such as a bayonet or snap fastener, that engages with a corresponding counterpart at the distal end portion of the mouthpiece. If the device does not include a mouthpiece, then an aerosol generating article for use with an aerosol generating device may include a mouthpiece, such as a filter plug.

The aerosol generating device may include at least one air outlet, such as an air outlet in a mouthpiece (if any).

Preferably, the aerosol generating device comprises an air path extending from said at least one air inlet, through the receiving heating cavity, and possibly further to the air outlet in the mouthpiece, if any. Preferably, the aerosol generating device comprises at least one air inlet in fluid communication with the receiving cavity. Accordingly, the aerosol generating system may include an air path extending from said at least one air inlet to the receiving cavity and possibly further through the aerosol generating substrate within the article and through the mouthpiece into the user's mouth.

Additional features and advantages of the aerosol generating device according to the present invention have been described in relation to the heating unit and will not be described again.

The present invention also provides an aerosol generating system. The system comprises an aerosol generating device, an aerosol generating article for use with said aerosol generating device, and an induction heating assembly according to the present invention described herein. The induction source of the heating unit is part of the aerosol generating device. The first current collector of the current collector assembly is part of an aerosol generating article, while the second current collector of the current collector assembly is either a part of an aerosol generating article or a part of an aerosol generating device.

Preferably, the first current collector as part of the aerosol generating article may be configured to heat the aerosol generating substrate. To this end, the first pantograph can be optimized with regard to heat loss and hence heating efficiency. For example, the first current collector may be a current collector strip, a current collector plate, a current collector rod, a current collector pin, a current collector mesh, a current collector thread, or a particulate current collector located adjacent to the aerosol generating substrate of the aerosol generating article.

In contrast, the second pantograph may be configured to primarily monitor the temperature of the pantograph. To this end, the second current collector can be either a part of an aerosol-generating article, in particular located inside it, or a part of an aerosol-generating device. In any configuration, if the article is used in conjunction with, in particular attached to, the device, the second current collector is preferably located in thermal proximity to or even in thermal contact with the first current collector and/or the aerosol-forming substrate. This provides the advantage that the second current collector has substantially the same temperature as the first current collector and/or the aerosol generating substrate during operation of the aerosol generating system. In this way, it is possible to achieve proper and accurate temperature control. For example, the second current collector may be located on the inner wall of the receiving cavity of the aerosol generating device.

If present, the controller of the heating unit may be part of the aerosol generating device, in particular located inside it. Preferably, the controller of the aerosol generating device may comprise or may be a heating unit controller.

Similarly, if present, the power source of the heating unit may be a part of the aerosol generating device, in particular, located inside it. Preferably, the power source for the aerosol generating device may comprise or may be a power source for a heating unit.

The aerosol generating device may include a receiving cavity for receiving at least a portion of the aerosol generating article.

In addition to the specific configuration of the current receiving unit of the heating unit, the aerosol generating product of the aerosol generating system may be the aerosol generating product according to the present invention described above.

Additional features and advantages of the aerosol generating system according to the present invention have been described above with respect to the current collector assembly, the aerosol generating article, and the heating assembly, and will not be described again.

The present invention will now be described solely by way of example with reference to the accompanying drawings, in which:

The present invention will now be described solely by way of example with reference to the accompanying drawings, in which:

in FIG. 1 is a schematic illustration of an aerosol generating system comprising an inductively heated aerosol generating device and an aerosol generating article comprising a current collector assembly according to a first exemplary embodiment of the present invention;

in FIG. 2 is a schematic illustration of an aerosol generating article capable of induction heating according to FIG. 1;

in FIG. 3 is a perspective view of the current-collecting assembly of the aerosol-generating article of FIG. 1 and FIG. 2;

in FIG. 4 is a diagram schematically illustrating the resistance versus temperature profile of a current collector assembly according to the present invention;

in FIG. 5-7 show alternative embodiments of a current collector assembly for use with the product of FIG. 1 and FIG. 2;

in FIG. 8-10 show aerosol generating articles for use with the apparatus of FIG. 1 which include further alternative embodiments of the current collector assembly;

in FIG. 11 is a schematic illustration of another aerosol generating system comprising a heating unit according to a second exemplary embodiment of the present invention;

in FIG. 12 is a perspective view of a current collector included in the aerosol generating device of FIG. eleven;

in FIG. 13-15 show alternate embodiments of a current collector assembly for use with the apparatus of FIG. eleven;

in FIG. 16 is a schematic illustration of an aerosol generating system comprising a heating unit according to a third exemplary embodiment of the present invention;

in FIG. 17 is a schematic illustration of an aerosol generating system comprising an electrical heating unit according to a fourth exemplary embodiment of the present invention;

in FIG. 18 is a schematic illustration of an aerosol generating system comprising a heating unit according to a fifth exemplary embodiment of the present invention; And

in FIG. 19 is a schematic illustration of an aerosol generating system comprising a heating unit according to a sixth exemplary embodiment of the present invention.

On FIG. 1 schematically shows a first exemplary embodiment of an aerosol generating system 1 according to the present invention. System 1 comprises an aerosol generating device 10 according to the present invention, as well as an aerosol generating article 100 which is configured for use with said device and contains an aerosol generating substrate to be heated.

In FIG . 2 shows additional details of an aerosol-generating article 100, said aerosol-generating article 100 having a substantially rod-like shape and comprising four elements arranged in series with coaxial alignment: an aerosol-generating rod segment 110, containing a current-collecting element 120 and an aerosol-generating substrate 130, a support element 140, having a central air path 141, an aerosol cooling element 150, and a filter element 160 that serves as a mouthpiece. The aerosol generating rod segment 110 is located at the distal end 102 of the article 100, while the filter element 160 is located at the proximal end 103 of the article 100. Each of these four elements is a substantially cylindrical element, and they all have essentially the same diameter. In addition, said four elements are surrounded by an outer wrap 170 so as to hold said four elements together and maintain the desired circular cross-sectional shape of the rod-like product 100. The wrap 170 is preferably made of paper. Additional details about the product, in particular about these four elements, in addition to the features of the current-collecting element 120 inside the rod segment 110, are disclosed in WO 2015/176898 A1.

As shown in FIG. 1, the aerosol-generating device 10 includes a cylindrical receiving cavity 20 formed within the proximal part 12 of the device to accommodate at least the distal part of the product 100. The device 10 also includes an induction source containing an inductor 30 for generating an alternating, in particular high-frequency, electromagnetic field. In this embodiment, the inductor 30 is a helical coil circumferentially surrounding a cylindrical receiving cavity 20. The coil 30 is positioned such that the current-collecting member 120 of the aerosol-generating article 100 is exposed to an electromagnetic field when the article 100 interacts with the device 10. Thus, when activation of the induction source, the current-collecting element 120 is heated due to eddy currents and/or hysteresis losses that are created under the action of an alternating electromagnetic field, depending on the magnetic and electrical properties of the materials of the current-collectors of the current-collector assembly 120. The current-collector element 120 is heated until reaches an operating temperature sufficient to vaporize the aerosol-forming substrate 130 surrounding the current-collecting member 120 within the article 100.

Within the distal portion 13, the aerosol generating device 10 also includes a DC power supply 40 and a controller 50 (shown only schematically in FIG. 1) for powering and controlling the heating process. With regard to electronics, the induction source, with the exception of the inductor 30, is preferably at least partially integral to the controller 50.

Both the induction source as part of the device 10 and the current collector 120 as part of the aerosol generating article 100 form the main parts of the induction heating unit 5 according to the present invention.

On FIG. 3 is a detailed view of the current collector assembly 120 used within the aerosol generating article shown in FIG. 1 and FIG. 2. According to the present invention, the current collector assembly 120 comprises a first current collector 121 and a second current collector 122. The first current collector 121 comprises a first current collector material having a positive temperature coefficient of resistance, while the second current collector 122 comprises a ferromagnetic or ferrimagnetic material of the second current collector having a negative temperature coefficient of resistance. drag coefficient. Due to the materials of the first and second pantographs having opposite temperature coefficients of resistance, as well as due to the magnetic properties of the material of the second pantograph, the pantograph assembly 120 has a resistance versus temperature profile that contains a minimum resistance value near the Curie temperature of the second pantograph material.

The corresponding resistance versus temperature profile is shown in FIG. 4 . When starting the heating of the current collector 120 from room temperature T_R, the resistance of the material of the first current collector increases, while the resistance of the material of the second current collector decreases with increasing temperature T. The total apparent resistance R_a of the current collector 120 "seen" by the induction source of the device 10 used for induction heating current collector assembly 120 is determined by the combination of the respective resistance of the materials of the first and second current collectors. When the Curie temperature T_C of the material of the second current collector is reached from below, the decrease in the resistance of the material of the second current collector usually prevails over the increase in the resistance of the material of the first current collector. Accordingly, the overall apparent resistance R_a of the current collector assembly 120 decreases in a temperature range below, in particular near and below, the Curie temperature T_C of the material of the second current collector. At the Curie temperature T_C, the material of the second current collector loses its magnetic properties. This leads to an increase in the surface layer available for eddy currents in the material of the second current collector, which is accompanied by a sharp decrease in its resistance. Thus, as the temperature T of the current collector 120 increases further beyond the Curie temperature T_C of the material of the second current collector, the contribution of the resistance of the material of the second current collector to the total apparent resistance R_a of the current collector 120 decreases or even becomes negligible. Therefore, after passing through the minimum resistance value R_min near the temperature T_C of the second current collector, the total apparent resistance R_a of the current collector assembly 120 is determined mainly by the increase in the material resistance of the first current collector. In other words, the total apparent resistance R_a of the current collector 120 rises again in the direction of the operating resistance R_op at the operating temperature T_op. Advantageously, this decrease and subsequent increase in the resistance versus temperature profile near the minimum value R_min near the Curie temperature T_C of the second current collector material is quite distinct from the temporal change in apparent impedance during user tightening. As a result, it is possible to reliably use the minimum resistance value R_a in the vicinity of the Curie temperature T_C of the second current collector as a temperature marker to control the heating temperature of the aerosol-forming substrate without the risk of being misinterpreted as a result of puffing by the user. Accordingly, it is possible to effectively prevent unwanted overheating of the aerosol-forming substrate.

In order to adjust the heating temperature of the aerosol-forming substrate to match the desired operating temperature T_op, the controller 50 of the device 10 shown in FIG. 1 is configured to control the operation of the induction source in a closed loop offset configuration such that the actual apparent resistivity is maintained at a value that corresponds to the sum of a determined minimum apparent resistivity value R_min and a predetermined bias value ΔR_offset. The offset value ΔR_offset levels the gap between the apparent resistance R_min measured at the marker temperature T_C and the operating resistance R_op at the operating temperature T_op. This provides the advantage of avoiding direct control of the heating temperature control based on a predetermined target value of apparent resistance at operating temperature T_op. In addition, heating temperature offset control is more stable and reliable than temperature control based on measured absolute values of apparent resistivity at the desired operating temperature.

If the actual apparent resistance is equal to or greater than the sum of the determined minimum impedance value and the predetermined apparent resistance offset value, then the heating process can be stopped by interrupting the generation of the alternating electromagnetic field, i.e. by turning off the induction source, or at least by reducing the output power of the induction source. If the actual apparent resistance is less than the sum of the determined minimum apparent resistance value and the determined apparent resistance offset value, then the heating process can be restarted by resuming the generation of the alternating electromagnetic field, i.e. by restarting the induction source or by re-raising the output power of the induction source.

In this embodiment, the operating temperature is approximately 370 degrees Celsius. This temperature is a typical operating temperature for heating, but not burning, the aerosol-forming substrate. To provide a sufficiently large temperature gap of at least 20 degrees Celsius between the marker temperature at temperature T_C of the material of the second current collector and the operating temperature T_op, the material of the second current collector is chosen so that it has a Curie temperature below 350 degrees Celsius.

As shown in FIG. 3, the current collector 120 within the article of FIG. 2 is a multi-layer current collector assembly, more specifically a two-layer current collector assembly. It contains a first layer, which forms the first current collector 121, and the second layer, which forms the second current collector 122, is located on and closely associated with the first layer. While the first pantograph 121 is optimized for heat loss and therefore heating efficiency, the second pantograph 122 is primarily a functional pantograph used as a temperature marker as described above. The current collector 120 is in the form of an elongated strip having a length L of 12 millimeters and a width W of 4 millimeters; in other words, both layers have a length L equal to 12 millimeters and a width W equal to 4 millimeters. The first pantograph 121 is a strip made of stainless steel having a Curie temperature of over 400°C, such as 430 grade stainless steel. It is approximately 35 micrometers thick. The second current collector 122 is a strip of mu-metal or permalloy having a Curie temperature below the operating temperature. It has a thickness of approximately 10 micrometers. The current collector assembly 120 is made by applying a second current collector strip to the first current collector strip.

On FIG. 5 shows an alternative embodiment of the strip current collector assembly 220, which is similar to the embodiment of the current collector assembly 120 shown in FIG. 1 and 2. Unlike the latter, the current collector 220 according to FIG. 5 is a three-layer current collector assembly which, in addition to the first and second current collectors 221, 222 forming the first and second layers, respectively, includes a third current collector 223 which forms the third layer. All three layers are stacked on top of each other, with adjacent layers closely connected to each other. The first and second pantographs 221, 222 of the three-layer pantograph assembly shown in FIG. 5 are identical to the first and second current collectors 121, 122 of the two-layer current collector assembly 120 shown in FIG. 1 and 2. The third pantograph 223 is identical to the first pantograph 221. In other words, the third layer 223 contains the same material as the first pantograph 221. In addition, the thickness of the layer of the third pantograph 223 is equal to the thickness of the layer of the first pantograph 221. Accordingly, the thermal expansion behavior the first and third pantographs 221, 223 is essentially the same. This configuration provides the advantage of a highly symmetrical layer structure showing substantially no out-of-plane deformations. In addition, the three-layer current-collecting assembly of FIG. 5 provides higher mechanical stability.

On FIG. 6 shows another embodiment of a strip current collector assembly 320 that may alternatively be used within the article of FIG. 2 instead of the two-layer current collector 120. The current collector assembly 320 according to FIG. 6 consists of a first pantograph 321 which is intimately coupled to a second pantograph 322. The first pantograph 321 is a 430 stainless steel strip measuring 12 millimeters by 4 millimeters by 35 micrometers. Thus, the first current collector 321 defines the basic shape of the current collector assembly 320. The second current collector 322 is a mu-metal or permalloy patch measuring 3 millimeters by 2 millimeters by 10 micrometers. The patch-shaped second pantograph 322 is galvanized onto the strip first pantograph 321. Although the second pantograph 322 is significantly smaller than the first pantograph 321, it is still sufficient to allow precise control of the heating temperature. The current collector 320 of FIG. 6 provides the advantage of significant savings in the material of the second pantograph. In additional embodiments (not shown), more than one second pantograph pad may be present in intimate contact with the first pantograph.

On FIG. 7 shows another embodiment of a current collector assembly 1020 for use with the product shown in FIG. 1 and FIG. 2. According to this embodiment, the current collector assembly 1020 forms a current collector bar. The current-collecting rod is a cylinder having a circular cross section. Preferably, the susceptor rod is positioned exactly centrally within the aerosol-forming substrate such that it extends the longitudinal axis of the article shown in FIG. 2. As can be seen on one of its end faces, the current collector assembly 1020 includes an internal core current collector that forms the second current collector 1022 according to the present invention. Said core current collector is surrounded by a shell current collector, which forms the first current collector 1021 according to the present invention. Since the first current collector 1021 preferably has a heating function, this configuration is useful in terms of directly transferring heat to the surrounding aerosol-forming substrate. In addition, the cylindrical shape of the current-collecting pin provides a highly symmetrical heating profile, which can be useful with a rod-shaped aerosol generating article.

On FIG. 8-10 schematically show other aerosol generating articles 400, 500, 600 containing additional embodiments of a current collector assembly that is part of a heating assembly according to the present invention. Articles 400, 500, 600 are very similar to article 100 shown in FIG. 1 and 2, in particular with regard to the overall layout of the product. Therefore, similar or identical elements are designated with the same reference numerals as in FIG. 1 and FIG. 2, but increased by 300, 400 and 500.

Unlike product 100 shown in FIG. 1 and 2, the aerosol generating article 400 of FIG. 8 includes a thread-like current collector assembly 420. In other words, the first and second current collectors 421, 422 are threads that are twisted with each other such that they form a twisted pair of threads. Said pair of filaments is positioned centrally within the aerosol-forming substrate 430 in direct contact with the substrate 430. Said pair of filaments substantially extends along the length of the article 400. The first current collector 421 is a filament made of ferromagnetic stainless steel and thus having primarily the function heating. The second current collector 422 is a filament made of mu-metal or permalloy and therefore serves primarily as a temperature marker.

The aerosol generating article 500 of FIG. 9 includes a particulate current collector assembly 520. Both of the first current collector 521 and the second current collector 522 comprise a plurality of current collector particles distributed within the aerosol-forming substrate 530 of the article 500. this serves primarily to heat the surrounding aerosol-forming substrate 530. In contrast, the current-collecting particles of the second current collector 422 are made of mu-metal or permalloy and therefore serve primarily as a temperature marker.

The aerosol generating article 600 of FIG. 10 includes a current collector assembly 600 comprising a first current collector 621 and a second current collector 622 that have different geometries. The first current collector 621 is a particulate current collector containing a plurality of current-collecting particles dispersed in the aerosol-forming substrate 630. Due to its particulate nature, the first current collector 621 provides a large surface area for the surrounding aerosol-forming substrate 630, which allows the advantage of improved heat transfer. Accordingly, the particulate configuration of the first pantograph 621 is specially selected with respect to the heating function. In contrast, the second pantograph 622 mainly has a temperature control function and therefore does not need a very large surface area. Accordingly, the second current collector 622 according to the present embodiment is a current-collecting strip extending inside the aerosol-generating substrate 630 through the center of the aerosol-generating article 600.

On FIG. 11 schematically shows a second illustrative embodiment of an aerosol generating system 2001 according to the present invention. System 2001 is very similar to system 1 shown in FIG. 1, with the exception of the current collector. In this regard, similar or identical elements are designated by the same reference numbers as in FIG. 1 and 2 but magnified by 2000. Unlike the embodiment shown in FIG. 1, the current collector 2060 of the heating unit 2005 according to the embodiment of FIG. 11 is part of the aerosol generating device 2010. Thus, the system 2001 includes a heating assembly 2005 according to the present invention, which is exclusively part of the aerosol generating device 2010.

Accordingly, the aerosol generating article 2100 does not include any current collector assembly. Thus, product 2100 generally corresponds to product 100 shown in FIG. 1 and 2, but does not have a current collector.

Similarly, the aerosol generating device 2010 of FIG. 11 generally corresponds to the device 10 shown in FIG. 1. Unlike the latter, the device 2010 includes all parts of the heating unit 2005. In other words, the device 2010 includes an induction source containing a helical inductor 2030, which is surrounded by a cylindrical receiving cavity 2020. In addition, the device also contains a current-collecting unit 2060, which is located inside the receiving cavity so as to be exposed to the electromagnetic field generated by the inductor 2030.

The current collector assembly 2060 is a current collector plate. At its distal end 2064, the current collector plate 2060 is located at the bottom of the receiving cavity 2020 of the device 2010. From there, the current collector plate extends into the interior of the receiving cavity 2020 towards the opening of the receiving cavity 2020. The receiving cavity opening 2020 is located at the proximal end 2014 of the aerosol generating device 2010, thus providing thus, the possibility of inserting an aerosol generating article 2100 into the receiving cavity 2020.

As can be seen in particular from FIG. 12 , the current collector assembly 2060 of the device 2010 of FIG. 11 is a two layer current collector plate very similar to the two layer current collector assembly 120 shown in FIG. 1-3. Unlike the latter, the distal free end 2063 of the current collector assembly 2060 tapers so that the plate-like current collector assembly can easily penetrate the aerosol-forming substrate 2130 within the distal end of the aerosol-generating article 2100.

In addition, the current receiving unit 2060 and the heating unit 2005 of the aerosol generating system 2001 of FIG. 11 show the same resistance versus temperature profile as the aerosol generating system of FIG. 1, that is, the profile shown in FIG. 4.On

On FIG. 13 , Fig. 14 and FIG. 15 shows further embodiments of current collector assemblies 2160, 2260, 2360 according to the present invention, which may alternatively be used with the apparatus of FIG. 11. Current collector nodes 2160, 2260, and 360 generally correspond to current collector nodes 220, 320, and 1020 shown in FIG. 5, Fig. 6 and FIG. 7 respectively. In this regard, most of the features and benefits of these current collector nodes 2160, 2260, 2360 have been described in relation to the current collector nodes 220, 320, 1020 and therefore will not be described again. Similar to the current collector assembly 120, the corresponding distal free end 2163, 2263, 2361 of the current collector nodes 2160, 2260, 2360 tapers to facilitate penetration into the aerosol-forming substrate.

On FIG. 16-18 schematically illustrate additional embodiments of aerosol generating systems 2701, 2801, 2901 according to the present invention, in which the respective induction heating assembly 2705, 2805, 2905 is exclusively part of the respective aerosol generating device 2710, 2810, 2910. Systems 2701, 2801 and 2901 are very similar to system 2001 shown in FIG. 11, in particular with regard to the general layout of devices 2710, 2810, 2910 and products 2700, 2800, 2900. Thus, similar or identical elements of devices are designated by the same reference numbers as in FIG. 11, but increased by 700, 800 and 900, respectively.

Unlike the device 2010 shown in FIG. 11, the aerosol generating device 2710 of the aerosol generating system 2701 of FIG. 16 includes a current collector assembly 2760 in which the first current collector (susceptor) 2761 and the second current collector 2762 have different geometries. The first current collector 2761 is a single layer current collector plate similar to the two layer current collector assembly 2060 shown in FIG. 11 and FIG. 12, but without the second current-collecting layer. In this configuration, the first pantograph 2761 generally forms an induction heating plate since it mainly has a heating function. In contrast, the second current collector 2762 is a current collector sleeve that forms at least a portion of the circumferential inner side wall of the receiving cavity 2720. the inner wall of the cylindrical receiving cavity 2720, while the second current collector may be a single layer current collector plate to be inserted into the aerosol-forming substrate. In the latter configuration, the first current collector may form an induction furnace heater or a heating chamber. In either of these configurations, the first and second current collectors 2761, 2762 are located at different locations within the aerosol generating device 2710 spaced apart but still in thermal proximity to each other.

Aerosol generating device 2810 of the aerosol generating system 2801 shown in FIG. 17 includes a susceptor assembly 2860 which is a susceptor cup, and thus an induction furnace heater or a heating chamber is implemented. In this configuration, the first current collector 2861 is a current collector sleeve forming the side wall of the cup-shaped current-collecting assembly 2860 and, therefore, at least a portion of the inner side wall of the cylindrical receiving cavity 2820. In contrast, the second current-collector 2862 forms the lower part of the cup-shaped current-collecting assembly 2860. Both of the first and second current collectors 2861, 2862 are in thermal proximity to the aerosol-generating substrate 2130 of the aerosol-generating article 2100 when placed in the receiving cavity 2820 of the device 2810.

Aerosol generating device 2910 of the aerosol generating system 2901 shown in FIG. 18 includes a current collector assembly 2960, which is a multilayer current collector sleeve. In this configuration, the second current collector 2962 forms the outer wall of the multilayer current collector sleeve, while the first current collector 2961 forms the inner wall of the multilayer current collector sleeve. This specific arrangement of the first and second current collectors 2961, 2962 is advantageous because in this way the first current collector 2961, used primarily to heat the substrate 2130, is located closer to the substrate 2130. Preferably, the current collector assembly 2960 also forms an induction furnace heater or heating camera.

On FIG. 19 schematically shows another embodiment of an aerosol generating system 3701 according to the present invention. System 3701 is very similar to system 2701 shown in FIG. 16. In this regard, similar or identical elements are designated by the same reference numbers as in FIG. 16 but magnified by 1000. Unlike the embodiment shown in FIG. 16, the current collector 3760 of the heater 3705 according to the embodiment of FIG. 16 divided. While the first current collector 3761 of the current collector assembly 3760 is part of the aerosol generating article 3100, the second current collector 3762 of the current collector assembly 3760 is part of the aerosol generating device 3710. The first current collector (susceptor) 3761 is a single layer current collector strip similar to the two layer current collector assembly 120 shown in FIG. 1-3, but placed within the aerosol-forming substrate 3130 of article 3100 and not having a second current-collecting layer. Thus, the first current collector 3761 generally forms an induction heating element as an integral part of the article 3100. The second current collector 2762 is a current collector sleeve that forms at least a portion of the circumferential inner side wall of the receiving cavity 2720 to form an induction furnace or heating chamber heater. Despite being distant from the first pantograph 3761, the second pantograph 3762 is still in thermal proximity to the first pantograph 3761 and the aerosol-forming substrate 3130, and thus can be conveniently used as a temperature marker.

For all three embodiments shown in FIG. 16-19, the first current collector is preferably made of a ferromagnetic stainless steel that is optimized for heating the aerosol-forming substrate. In contrast, the second current collector is preferably made of mu-metal or permalloy, which is a suitable material for a temperature marker.

Claims (19)

1. A susceptor assembly for induction heating of an aerosol-forming substrate under the action of an alternating magnetic field, the susceptor assembly comprising a first susceptor containing a first susceptor material and a second susceptor containing a second susceptor material, the materials of the first and second susceptors being selected such that during preheating of the susceptor assembly starting at room temperature, the resistance versus temperature profile of the susceptor assembly has a minimum resistance value in the temperature range of ±5° C. relative to the Curie temperature of the second susceptor material. 2. The susceptor assembly according to claim 1, wherein the second susceptor material has a Curie temperature below 350°C, in particular below 300°C, preferably below 250°C, most preferably below 200°C. 3. A susceptor assembly according to any one of the preceding claims, wherein the first susceptor material has a positive temperature coefficient of resistance and the second susceptor material has a negative temperature coefficient of resistance. 4. A susceptor assembly according to any one of the preceding claims, wherein the second susceptor contains one of mu-metal or permalloy. 5. A susceptor assembly according to any one of the preceding claims, wherein the material of the first susceptor is electrically conductive and/or one of paramagnetic, ferromagnetic, or ferrimagnetic. 6. A susceptor assembly according to any one of the preceding claims, wherein the material of the first susceptor comprises one of the following: aluminum, iron, nickel, copper, bronze, cobalt, carbon steel, stainless steel, ferritic stainless steel, martensitic stainless steel, or austenitic stainless steel. 7. A susceptor assembly according to any one of the preceding claims, wherein the first susceptor and the second susceptor are in close physical contact with each other. 8. The susceptor assembly according to any one of the preceding claims, wherein the first susceptor or the second susceptor or both of the first and second susceptors, in particular the entire susceptor assembly, is one of the following: a particulate susceptor, or a susceptor thread, or a susceptor mesh, or a susceptor wick, or a susceptor pin, or a susceptor rod, or a susceptor plate, or a susceptor strip, or a susceptor sleeve, or a susceptor cup, or a cylindrical susceptor, or a flat susceptor. 9. An aerosol-generating article comprising an aerosol-forming substrate and a susceptor assembly according to any one of paragraphs. 1-8 for inductively heating an aerosol-forming substrate under an alternating magnetic field. 10. An induction heating unit configured to inductively heat an aerosol-forming substrate to a predetermined operating temperature, the heating unit comprising an induction source configured to generate an alternating electromagnetic field; And susceptor node according to any one of paragraphs. 1-8 for induction heating of an aerosol-forming substrate by an alternating magnetic field generated by an induction source. 11. The heating assembly of claim 10, further comprising a controller operatively coupled to the induction source and configured to control the operation of the induction source, particularly in a closed loop configuration, to control the heating of the aerosol-forming substrate to a predetermined operating temperature. 12. The heating assembly of claim 11, wherein the controller is configured to determine, during heating of the heating assembly in the direction of operating temperature, a minimum apparent resistance value indicative of a minimum resistance value of the susceptor assembly. 13. The heating unit according to any one of paragraphs. 10-12, in which the material of the second susceptor has a Curie temperature of at least 20°C, in particular at least 50°C, more specifically at least 100°C, preferably at least 150°C, most preferably at least 200° C. below operating temperature. 14. An aerosol generating device for generating an aerosol by heating an aerosol-forming substrate, the device comprising a receiving cavity for receiving an aerosol-forming substrate to be heated; induction heating unit according to any one of paragraphs. 10-13 for inductively heating an aerosol-forming substrate within said receiving cavity. 15. An aerosol generating system comprising an aerosol generating device and an aerosol generating article for use with said aerosol generating device; the system also contains an induction heating unit according to any one of paragraphs. 10-13, wherein the induction source of the heating assembly is part of an aerosol-generating article, wherein the first susceptor of the susceptor assembly is part of an aerosol-generating article, and the second susceptor of the susceptor assembly is a part of an aerosol-generating article or part of an aerosol-generating device.

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