Heater for aerosol generator with multiple susceptor sets

Abstract

The heater assembly for an aerosol-generating device includes a heating chamber (14) for heating an aerosol-forming substrate, a first set of susceptors (16) configured to heat a first heating zone (20) of the heating chamber, and a second set of susceptors (18) configured to heat a second heating zone (22) of the heating chamber. The first heating zone and the second heating zone are disposed at different longitudinal positions of the heating chamber. The susceptors may be mounted on a common, raised support base (30). The second set of susceptors (18) may be longer than the first set of susceptors (16) and are paddle-shaped with stems (46) and heating surfaces (50).

Description

[Technical field]

[0001] The present disclosure relates to a heater assembly for an aerosol generating device.The present disclosure further relates to an aerosol generating device.The present disclosure further relates to an aerosol generating system comprising an aerosol generating device and an aerosol generating article. [Background technology]

[0002] It is known to provide an aerosol-generating device for generating an inhalable vapor. Such a device may heat an aerosol-forming substrate contained in an aerosol-generating article without burning the aerosol-forming substrate. The aerosol-generating article may have a rod shape for inserting the aerosol-generating article into a heating chamber of the aerosol-generating device. A heating element is disposed in or around the heating chamber for heating the aerosol-forming substrate after the aerosol-generating article is inserted into the heating chamber of the aerosol-generating device.

[0003] The aerosol-generating article should be held securely within the heating chamber during use. The aerosol-generating article should be held with sufficient force to prevent it from falling out of the heating chamber, which would prevent the device from generating aerosols.

[0004] It is known to use induction heating, whereby an alternating current in an inductor coil induces an alternating magnetic field. This alternating magnetic field is called an induction field because it can induce alternating ring currents (eddy currents) in the susceptor if the susceptor is conductive. If the susceptor is magnetic, hysteresis losses occur in the susceptor. A susceptor that is both conductive and magnetic causes the susceptor to heat up due to both effects (eddy currents and hysteresis losses). Generally, a material that is heated when penetrated by an alternating magnetic field is called a susceptor. The heat thus generated is then propagated to the aerosol-generating substrate, heating it and thus generating the aerosol. Some induction heating devices are designed to have multiple heating zones, i.e. the heating system can heat only sub-portions of the total consumable. This can be done, for example, to allow a single consumable to be used multiple times, or to allow a single consumable to provide different user experiences depending on the sub-portion used to generate the aerosol, or simply to achieve a more uniform user experience over a longer period of time. It is known to use different inductor coils to heat different heating zones of a susceptor.

[0005] It would be desirable to have an aerosol generating apparatus that can reduce the amount of energy consumed by the heater assembly. It would be desirable to have an aerosol generating apparatus that can selectively heat specific heating zones of a plurality of heating zones. It would be desirable to have an aerosol generating apparatus that can reduce heat transfer between different heating zones. It would be desirable to have an aerosol generating apparatus that can reduce the thermal mass of the susceptor.

[0006] Additionally, it would be desirable to have an aerosol-generating device that can provide intimate thermal contact between the susceptor and the aerosol-forming substrate. It would be desirable to have an aerosol-generating device that can securely hold the aerosol-generating article within the heating chamber. It would be desirable to have an aerosol-generating device that can allow the aerosol-generating article to be easily inserted into and removed from the heating chamber. Summary of the Invention

[0007] According to one embodiment of the present invention, there is provided a heater assembly for an aerosol generating device. The heater assembly may include a heating chamber for heating an aerosol-forming substrate. The heater assembly may include a first set of susceptors configured to heat a first heating zone of the heating chamber. The heater assembly may include a second set of susceptors configured to heat a second heating zone of the heating chamber. The first heating zone and the second heating zone may be disposed at different longitudinal positions of the heating chamber.

[0008] According to one embodiment of the present invention, there is provided a heater assembly for an aerosol generating device. The heater assembly includes a heating chamber for heating an aerosol-forming substrate. The heater assembly includes a first set of susceptors configured to heat a first heating zone of the heating chamber. The heater assembly further includes a second set of susceptors configured to heat a second heating zone of the heating chamber. The first heating zone and the second heating zone are disposed at different longitudinal positions of the heating chamber.

[0009] By providing the heater assembly of the present invention, the amount of energy consumed by the heater assembly can be reduced. By providing the heater assembly of the present invention, a particular heating zone of a plurality of heating zones can be selectively heated. By providing the heater assembly of the present invention, the heat transfer between different heating zones can be reduced. By providing the heater assembly of the present invention, the thermal mass of the susceptor can be reduced.

[0010] By providing a heater assembly of the present invention, intimate thermal contact between the susceptor and the aerosol-forming substrate can be achieved. By providing a heater assembly of the present invention, an aerosol generating device can be provided which securely holds the aerosol-generating article within the heating chamber. By providing a heater assembly of the present invention, an aerosol generating device can be provided which allows the aerosol-generating article to be easily inserted into and removed from the heating chamber.

[0011] Preferably, the heater assembly is an integral part of the aerosol generating device.

[0012] The first heating zone may be disposed distal to the second heating zone relative to a longitudinal axis of the heating chamber.

[0013] Having a separate set of susceptors for each heating zone may advantageously reduce thermal contact between susceptors in different heating zones. This may reduce inadvertent heat transfer between different heating zones. Heat containment within a particular heating zone may advantageously be improved. Selective heating of individual heating zones may be improved. Heat losses between heating zones may be reduced. Energy consumption may be reduced.

[0014] As used herein, the term "susceptor set" refers to multiple susceptors, meaning, for example, two or more susceptors in a set, for example, three or more, four or more, five or more, six or more, seven or more, or eight or more susceptors. Having multiple susceptors for each heating zone can reduce the total mass of susceptor material compared to having one large single susceptor for a complete heating zone. This can reduce one or both of the thermal mass and thermal inertia of the susceptor material for each heating zone. This can require less energy to heat the heating zone to a desired temperature. This can allow the heating zone to heat up to a desired temperature more quickly. Having multiple susceptors for each heating zone can improve the mechanical flexibility of the susceptor arrangement.

[0015] One or both of the susceptors of the first and second sets may be flexible in a direction perpendicular to the longitudinal axis of the heating chamber to securely hold the aerosol-generating article after insertion into the heating chamber. As used herein, the direction perpendicular to the longitudinal axis of the heating chamber corresponds to the transverse direction.

[0016] One or both of the susceptors of the first and second sets may be elongated along the longitudinal axis of the heating chamber. The longitudinal axes of one or both of the susceptors of the first and second sets may be collinear with the longitudinal axis of the heating chamber. This may advantageously provide transverse flexibility of the susceptors for carrying the aerosol-generating article.

[0017] There may be gaps between the individual susceptors of a set of susceptors, which may allow for transverse airflow through the gaps.

[0018] One or both of the first and second sets of susceptors may be disposed circumferentially around the heating chamber.

[0019] The susceptors of the first set of susceptors and the susceptors of the second set of susceptors may be arranged in an alternating manner such that a susceptor of the first set is adjacent to two susceptors of the second set. The susceptors of the first set of susceptors and the susceptors of the second set of susceptors may be arranged in an alternating manner along a transverse circumferential direction such that a susceptor of the first set is adjacent to two susceptors of the second set in a transverse circumferential direction.

[0020] One or both susceptors of the first and second sets of susceptors may include several portions. The susceptor may include a stem for mounting the susceptor on a support base at its distal end. The susceptor may include a heating portion for heating an aerosol-forming substrate of the aerosol-generating article. The heating portion may include a heating surface. The heating surface may be a flat portion configured for intimate thermal contact with the aerosol-generating article. The susceptor may include a tip portion at its proximal end. The tip portion may be curved in a transverse direction perpendicular to the longitudinal direction of one or both of the susceptor and the heating chamber. The bending of the tip portion of the susceptor may result in a flared arrangement of the set of susceptors. This may facilitate the insertion of the aerosol-generating article into the heating chamber.

[0021] A gap may be provided between the heating surfaces of the susceptors of the first set of susceptors and the heating surfaces of the susceptors of the second set of susceptors.Gaps may be provided between the heating surfaces of the susceptors within the set of susceptors.

[0022] At least a portion of one or both of the susceptors in the first and second sets may include a curved shape aligned with the longitudinal axis of the heating chamber. At least a portion of one or both of the susceptors in the first and second sets may include an S-shape aligned with the longitudinal axis of the heating chamber. The curved or S-shape may configure the susceptor such that only the heated portion or heated surface of the susceptor is in intimate thermal contact with the aerosol-generating article in the respective heating zone.

[0023] The susceptors of the second set of susceptors may be longer than the susceptors of the first set of susceptors, measured parallel to the longitudinal axis of the heating chamber.

[0024] One or both of the susceptors of the first and second sets may include a thinner distal portion and a wider proximal portion. The thinner distal portion may be configured to mount the susceptor to a fixture in an apparatus, such as a common base. The thinner distal portion may add mechanical flexibility, i.e., bendability, to one or both of the first and second sets of susceptors. The thinner distal portion may reduce heat transfer to the mounting fixture. With reduced heat transfer, the fixture does not need to be made of an expensive material that can withstand excessive heat, but can be made of a less expensive material, such as a hard plastic.

[0025] The susceptors of the second set of susceptors may form a paddle-like shape.

[0026] The heating surfaces of one or both of the susceptors of the first and second sets of susceptors may be arranged in a honeycomb pattern.

[0027] The shape of the susceptors in the first set of susceptors may be different from the shape of the susceptors in the second set of susceptors.The material of the susceptors in the first set of susceptors may be different from the material of the susceptors in the second set of susceptors.

[0028] The susceptor may be made entirely of a material that can be inductively heated. A portion of the susceptor may include a magnetically inert material. As used herein, the term "magnetically inert material" refers to a material that is not substantially heated when penetrated by an alternating magnetic field. A portion of the susceptor may include a material that is not a susceptor material. This means that the portion does not include a susceptor material that can be heated by penetration of a fluctuating magnetic field. Only the heating portion or the heating surface of the susceptor may include a susceptor material. For example, the heating surface may be covered by a susceptor material. Thus, in use, more energy of the fluctuating magnetic field may be available to heat the heating surface.

[0029] Magnetically inactive materials may include minerals, epoxy resins, polyesters, polyacrylamides, vinyl ester resins, wood, ceramics, alumina, zirconia, aramid, fiberglass, polyethylene, and glass-like materials.

[0030] As used herein, the portion of the susceptor that contains the susceptor material and is configured to be inductively heated is referred to as the "susceptor element."

[0031] As used herein, a "susceptor element" is a conductive element that heats up when subjected to a changing magnetic field. This may be the result of eddy currents induced in the susceptor element, or hysteresis losses, or both eddy currents and hysteresis losses. In use, the susceptor element is positioned in thermal contact or thermal proximity with an aerosol-forming substrate of an aerosol-generating article received in a heating chamber of a heater assembly of an aerosol-generating device. In this manner, the aerosol-forming substrate is heated by the susceptor element such that an aerosol is formed.

[0032] Advantageously, by providing a heating zone formed from a set of individual susceptors, the size, location, or size and location of the heating zone can be easily varied by changing one or more of the size, location, shape, and pattern of the susceptors. If only a portion of the susceptor includes susceptor elements, the remaining portion of the susceptor can be formed from a non-susceptor material, which can be lighter or less expensive than the susceptor material. Furthermore, the portion of the susceptor other than the susceptor elements can be formed from a thermally insulating material. This allows the heat generated in the susceptor elements to remain concentrated within the heating zone. Furthermore, the amount of heat lost to other components of the aerosol generating device can be reduced. For example, the degree to which the housing of the aerosol generating device heats up during use can be further reduced.

[0033] As used herein, the terms "thermally insulating" and "thermally insulative" refer to materials that have a bulk thermal conductivity of less than about 50 milliwatts per meter Kelvin (mW / (mK)) at 23°C and 50% relative humidity as measured using the modified transient plane source (MTPS) method.

[0034] The susceptor element may include a foil or film of susceptor material applied over the heating surface of the susceptor, for example, a foil or film of susceptor material glued or welded to the heating surface.

[0035] The susceptor element may be a susceptor coating deposited on the heated surface. For example, the susceptor coating may be painted or printed onto the heated surface as a liquid. The susceptor coating may be deposited on the heated surface of the susceptor by a vacuum deposition process such as evaporation or by sputtering. The susceptor coating may be deposited on the heated surface by electrodeposition.

[0036] The susceptor element may be made of any material that can be inductively heated to a temperature sufficient to aerosolize the aerosol-forming substrate. Suitable materials for the susceptor element include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Preferred susceptor elements include metal or carbon. Advantageously, the susceptor element includes or consists of a ferromagnetic material, such as ferritic iron, ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrite. Suitable susceptor elements may be or include aluminum. The susceptor element preferably includes more than 5 percent ferromagnetic or paramagnetic material, preferably more than 20 percent ferromagnetic or paramagnetic material, and more preferably more than 50 percent or more than 90 percent ferromagnetic or paramagnetic material. Preferred susceptor elements may be heated to a temperature of more than 250 degrees Celsius.

[0037] The susceptor element may include a metal or a metal alloy. The susceptor element may be formed from a metal or a metal alloy.

[0038] The susceptor element may include or be made of one or more of silicon carbide, molybdenum, graphite, stainless steel, stainless steel alloys, Kovar®, copper, copper tungsten alloys, copper molybdenum alloys, and electroplated conductors such as nickel, silver, gold, silver-platinum alloys, and silver-palladium alloys. The susceptor may be made of one or more of silicon carbide, molybdenum, graphite, and stainless steel.

[0039] At least a portion of the susceptor may include or be made from a shape-memory material, which may facilitate temporary support of the aerosol-generating article.

[0040] The first and second sets of susceptors may be mounted on a common base disposed at a distal end of the heating chamber. The common base may be raised. The common base may include or be made of a thermally insulating material, which may reduce heat transfer between the susceptors. As described herein, preferred thermal insulating materials include, for example, heat resistant plastics, glass, or polymeric materials, preferably air-containing, such as fibrous materials, aerogels, and foams.

[0041] The heater assembly comprises at least a first heating zone and a second heating zone. The heater assembly may comprise multiple heating zones. In use, the different heating zones may be heated to different temperatures. The multiple heating zones may be positioned directly adjacent to one another. The heater assembly may include different heating zones separated along the longitudinal axis of the heating chamber. This may allow the heating zones to be used to heat different parts of the aerosol-generating article that are in thermal proximity to different sets of susceptors, for example the same aerosol-forming substrate, or different aerosol-forming substrates, or different parts of the aerosol-forming substrate and aerosol former of the aerosol-generating article.

[0042] Multiple heating zones spaced along the longitudinal axis of the heating chamber may allow the heating zones to be used to heat different portions of the aerosol-generating article in thermal proximity to different sets of susceptors without inadvertently heating adjacent portions of the aerosol-generating article, such as heating an aerosol-forming substrate through a gap, such as heating a first aerosol-forming substrate in a first heating zone and heating a second aerosol-forming substrate in a second heating zone without substantially heating the second aerosol-forming substrate in the first heating zone, or substantially heating the first aerosol-forming substrate in the second heating zone.

[0043] The multiple heating zones may be formed from the same susceptor material. One or more of the heating zones may be formed from a susceptor having a different composition relative to the susceptor of at least one other heating zone, and therefore have different susceptor properties. This configuration may provide different heating profiles by the first and second heating zones due to the different susceptor properties of the first and second susceptor materials. The heat provided by each heating zone may be fine-tuned by the selection of the susceptor material forming part of each susceptor, or the material from which each susceptor is formed. This may also facilitate sequential heating of the susceptors, such as by forming the heating zones from a susceptor material in which optimal heating occurs at different frequencies of alternating current. The first and second heating zones may have different temperature cycles.

[0044] The heater assembly may include additional sets of susceptors and additional longitudinally separated heating zones. For example, the heater assembly may include a third set of susceptors configured to heat a third heating zone of the heating chamber. The heater assembly may include a fourth set of susceptors configured to heat a fourth heating zone of the heating chamber.

[0045] The heater assembly may include a first inductor coil for heating the first heating zone and a second inductor coil for heating the second heating zone.

[0046] The heater assembly may include a single inductor coil for heating both the first and second heating zones.

[0047] The heater assembly may comprise one or more inductor coils for heating at least a portion of one or both of the first and second sets of susceptors. The heater assembly may include a first inductor coil for heating the first set of susceptors and a second inductor coil for heating the second set of susceptors. The heater assembly may comprise a single inductor coil for heating both the first set of susceptors and the second set of susceptors.

[0048] The magnetic axis of the one or more inductor coils may be at an angle to the longitudinal axis of the heating chamber, i.e., non-parallel. In a preferred embodiment, the magnetic axis of the one or more inductor coils is substantially parallel to the longitudinal axis of the heating chamber. This may facilitate a more compact arrangement. It is preferred that at least a portion of the susceptor is substantially parallel to the magnetic axis of the one or more inductor coils. This may facilitate uniform heating of the susceptor element or susceptor by the one or more inductor coils. In a particularly preferred embodiment, the susceptor is substantially parallel to the magnetic axis of the one or more inductor coils and the longitudinal axis of the heating chamber.

[0049] The present invention further relates to an aerosol generating device comprising a heater assembly as described herein.

[0050] The aerosol generating device may include a controller connected to the one or more inductor coils and a power source. The controller may be configured to control the power supply from the power source to the inductors. The controller may comprise a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application specific integrated circuit chip (ASIC) or other electronic circuitry capable of providing control. The controller may comprise further electronic components. The controller may be configured to regulate the current supply to the one or more inductor coils. The current may be continuously supplied to the one or more inductor coils after activation of the aerosol generating device, or may be supplied intermittently (such as after every puff). The electrical circuitry may advantageously comprise a DC / AC inverter, which may comprise a class D or class E power amplifier. The controller may be configured to independently control the first heating zone and the second heating zone. The controller may be configured to independently control the first inductor coil for heating the first heating zone and the second heating coil for heating the second heating zone.

[0051] The present invention further relates to an aerosol generation system comprising an aerosol generating device comprising a heater assembly as described herein and an aerosol-generating article including an aerosol-forming substrate, the aerosol-generating article may be configured to be at least partially inserted into the heating chamber.

[0052] The aerosol-generating article may include a first aerosol-forming substrate located at a first longitudinal position of the aerosol-generating article and configured to be heated by a first set of susceptors in a first heating zone when the aerosol-generating article is inserted into the heating chamber.The aerosol-generating article may include a second aerosol-forming substrate located at a second longitudinal position of the aerosol-generating article and configured to be heated by a second set of susceptors in a second heating zone when the aerosol-generating article is inserted into the heating chamber.

[0053] The aerosol-generating article may include a hollow tubular substrate portion that includes the aerosol-forming substrate. The hollow tubular substrate portion may be formed from a tubular tobacco mat.

[0054] The term "aerosol-forming substrate" as used herein refers to a substrate capable of releasing a volatile compound capable of forming an aerosol. The volatile compound may be released by heating or burning the aerosol-forming substrate. As an alternative to heating or burning, in some cases the volatile compound may be released by a chemical reaction or by mechanical stimulation such as ultrasound. The aerosol-forming substrate may be solid or liquid, or may include both solid and liquid components. The aerosol-forming substrate may be part of an aerosol-generating article.

[0055] As used herein, the term "aerosol-generating article" refers to an article that includes an aerosol-forming substrate capable of emitting a volatile compound capable of forming an aerosol. The aerosol-generating article may be disposable.

[0056] The term "aerosol-generating device" as used herein refers to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-generating device may interact with one or both of an aerosol-generating article that includes an aerosol-forming substrate and a cartridge that includes an aerosol-forming substrate. In some examples, the aerosol-generating device may heat the aerosol-forming substrate to facilitate the release of volatile compounds from the substrate. An electrically operated aerosol-generating device may include an atomizer, such as an electric heater, for heating the aerosol-forming substrate to form an aerosol.

[0057] As used herein, the term "aerosol-generating system" refers to the combination of an aerosol-generating device and an aerosol-forming substrate. When the aerosol-forming substrate forms part of an aerosol-generating article, the aerosol-generating system refers to the combination of an aerosol-generating device and an aerosol-generating article. In an aerosol-generating system, the aerosol-forming substrate and the aerosol-generating device work together to generate an aerosol.

[0058] As used herein, the term "longitudinal" is used to describe a direction along the major axis of a heater assembly, a major axis of an aerosol-generating device, a major axis of an aerosol-generating article, or a major axis of a component of an aerosol-generating device or article, and the term "transverse" is used to describe a direction perpendicular to the longitudinal axis. When referring to a heating chamber, the term "longitudinal" refers to the direction in which the aerosol-generating article is inserted into the chamber, and the term "transverse" refers to a direction perpendicular to the direction in which the aerosol-generating article is inserted into the chamber.

[0059] In general, the heating chamber may have an open end through which the aerosol-generating article is inserted and a closed end opposite the open end. In such embodiments, the longitudinal direction is the direction extending between the open end and the closed end. In certain embodiments, the longitudinal axis of the heating chamber is parallel to the longitudinal axis of the aerosol-generating device. For example, the open end of the chamber is located at the proximal end of the aerosol-generating device. In other embodiments, the longitudinal axis of the heating chamber is at an angle to the longitudinal axis of the aerosol-generating device, for example, transverse to the longitudinal axis of the aerosol-generating device. For example, the open end of the heating chamber is located along one side of the aerosol-generating device such that the aerosol-generating article can be inserted into the heating chamber in a direction perpendicular to the longitudinal axis of the aerosol-generating device.

[0060] As used herein, the term "proximal" refers to the user end or mouth end of the aerosol generating device, and the term "distal" refers to the end opposite the proximal end. Similarly, with respect to a heating assembly or susceptor, the term "proximal" refers to the direction closest to the user during use, and the term "distal" refers to the direction away from the user during use. Correspondingly, each of the aerosol generating device, heating assembly, susceptor, and heating chamber has a proximal end and an opposing distal end. When referring to a heating chamber or inductor coil, the term "proximal" refers to the area closest to the open end of the heating chamber, and the term "distal" refers to the area closest to the closed end. The ends of the aerosol generating device or heating chamber may also be referred to in terms of the direction in which air flows through the aerosol generating device. The proximal end may be referred to as the "downstream end" and the distal end may be referred to as the "upstream end."

[0061] As used herein, the term "length" refers to the major longitudinal dimension of a susceptor, a heating chamber, an aerosol-generating device, an aerosol-generating article, or a component of an aerosol-generating device or an aerosol-generating article.

[0062] As used herein, the term "width" refers to the major transverse dimension of a susceptor, a heating chamber, an aerosol-generating device, an aerosol-generating article, or a component of an aerosol-generating device or article, at a particular location along its length, and the term "thickness" refers to the transverse dimension perpendicular to the width.

[0063] Below is provided a non-exhaustive list of non-limiting examples, any one or more of the features of these examples may be combined with any one or more features of other examples, embodiments, or aspects described herein.

[0064] Example A: 1. A heater assembly for an aerosol generating device, comprising: a heating chamber for heating the aerosol-forming substrate; a first set of susceptors configured to heat a first heating zone of the heating chamber; a second set of susceptors configured to heat a second heating zone of the heating chamber; A heater assembly, wherein the first heating zone and the second heating zone are disposed at different longitudinal positions of the heating chamber. Example B: The heater assembly of embodiment A, wherein the first heating zone is disposed distal to the second heating zone relative to a longitudinal axis of the heating chamber. Example C: The heater assembly of embodiment A or embodiment B, wherein one or both susceptors of the first and second sets of susceptors are elongated along the longitudinal axis of the heating chamber. Example D: The heater assembly of any of embodiments A-C, wherein one or both of the first and second sets of susceptors are circumferentially disposed around the heating chamber. Example E: The heater assembly of embodiment D, wherein the susceptors of the first set of susceptors and the susceptors of the second set of susceptors are arranged in an alternating manner such that a susceptor of the first set is adjacent to two susceptors of the second set. Example F: A heater assembly described in any of Examples A-E, wherein one or both of the susceptors of the first and second sets are flexible in a direction perpendicular to the longitudinal axis of the heating chamber to securely hold an aerosol-generating article after being inserted into the heating chamber. Example G: The heater assembly of any of embodiments A-F, wherein at least a portion of one or both of the susceptors of the first and second sets includes a curved shape that is aligned with a longitudinal axis of the heating chamber. Example H: The heater assembly of embodiment G, wherein at least a portion of one or both of the susceptors of the first and second sets comprises an S-shape aligned along a longitudinal axis of the heating chamber. Example I: The heater assembly of any of embodiments A-H, wherein the susceptors of the second set of susceptors are longer than the susceptors of the first set of susceptors, measured parallel to the longitudinal axis of the heating chamber. Example J: The heater assembly of any of embodiments AI, wherein the susceptors of the second set of susceptors include a thinner distal portion and a wider proximal portion. Example K: The heater assembly of any of embodiments A-J, wherein the susceptors of the second set of susceptors form a paddle-like shape. Example L: The heater assembly of any of embodiments A-K, wherein the heating surfaces of one or both of the susceptors of the first and second sets of susceptors are arranged in a honeycomb pattern. Example M: The heater assembly of any of embodiments A-L, wherein a gap is provided between the heating surfaces of the susceptors of the first set of susceptors and the heating surfaces of the susceptors of the second set of susceptors. Example N: The heater assembly of any of embodiments A-M, wherein a gap is provided between the heating surfaces of the susceptors within the set of susceptors. Example O: The heater assembly of any of embodiments AN, wherein a susceptor shape of the first set of susceptors is different than a susceptor shape of the second set of susceptors. Example P: The heater assembly of any of embodiments A-O, wherein a susceptor material for the first set of susceptors is different from a susceptor material for the second set of susceptors. Example Q: The heater assembly of any of embodiments AP, wherein the first and second sets of susceptors are mounted on a common base disposed at a distal end of the heating chamber. Example R: The heater assembly of any of embodiments A-Q, comprising a first inductor coil for heating the first set of susceptors and a second inductor coil for heating the second set of susceptors. Example S: The heater assembly of any of embodiments A-Q including a single inductor coil for heating both the first set of susceptors and the second set of susceptors. Example T: The heater assembly of any of Examples A-S, wherein at least a portion of the susceptor comprises or is made from an electroplated conductor, such as silicon carbide, molybdenum, graphite, stainless steel, stainless steel alloy, Kovar®, copper, copper tungsten alloy, copper molybdenum alloy, and nickel, silver, gold, silver-platinum alloy, and silver-palladium alloy. Example U: The heater assembly of any of embodiments A-T, wherein at least a portion of the susceptor comprises or is made of a shape memory material. Example V: An aerosol generating device comprising a heater assembly according to any one of Examples A to U. Example W: An aerosol generation system comprising an aerosol generating device as described in Example V and an aerosol-generating article comprising an aerosol-forming substrate, the aerosol-generating article being configured to be at least partially inserted into a heated chamber. Example X: The aerosol generating system of example W, wherein the aerosol-generating article comprises a first aerosol-forming substrate located at a first longitudinal position of the aerosol-generating article when the aerosol-generating article is inserted into the heating chamber and configured to be heated by a first set of susceptors in a first heating zone, and a second aerosol-forming substrate located at a second longitudinal position of the aerosol-generating article when the aerosol-generating article is inserted into the heating chamber and configured to be heated by a second set of susceptors in a second heating zone.

[0065] Features described with respect to one embodiment may equally be applied to other embodiments of the invention.

[0066] The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0067] [Figure 1] FIG. 1 illustrates a heater assembly of the present invention. [Diagram 2] 2a-2f show individual susceptors. [Diagram 3] FIG. 3 shows two sets of susceptors in an alternating arrangement. [Figure 4] 4a and 4b show an aerosol-generating article and an article that is inserted into a heater assembly of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0068] 1a and 1b show a heater assembly 10 of the present invention in cross-section as part of an aerosol-generating device. A dotted line indicates a central longitudinal axis 12 of the heater assembly 10. The heater assembly 10 comprises a heating chamber 14 for heating an aerosol-forming substrate of an aerosol-generating article. Two sets of susceptors, a first set of susceptors 16 and a second set of susceptors 18, are circumferentially disposed in a distal portion of the heating chamber 14. FIGS. 1a and 1b show the same heater assembly 10. However, FIG. 1b visualizes that the first set of susceptors 16 are configured to heat a first heating zone 20 of the heating chamber 14 and the second set of susceptors 18 are configured to heat a second heating zone 22 of the heating chamber 14. The first heating zone 20 and the second heating zone 22 are disposed at different longitudinal positions of the heating chamber 14. The heater assembly 10 further comprises a first inductor coil 24 for heating the first set of susceptors 16 and a second inductor coil 26 for heating the second set of susceptors 18. The first inductor coil 24 and the second inductor coil 26 are disposed to correspond to different longitudinal positions of the heating chamber 14 coaxially surrounding the susceptor arrangement. A thermal insulating tube 28 is provided coaxially between the inductor coils 24, 26 and the susceptors 16, 18.

[0069] The susceptors 16, 18 are mounted on a raised common support base 30 at the distal end of the heating chamber 14. The heater assembly 10 also includes a distal thermal insulator member 32, an air inlet 34, a sealing member 36, and a housing 38.

[0070] The individual susceptors 16, 18 do not physically contact each other. There are gaps between adjacent susceptors 16, 18. Thus, there are gaps between susceptors 16, 18 of different sets of susceptors. The gaps between susceptors 16, 18 of different sets reduce heat transfer between different heating zones.

[0071] There are also longitudinal gaps between the susceptors within a set that allow lateral air flow from the air inlet 34 through the gaps between the susceptors and into the central region of the heating chamber 14 at the central longitudinal axis 12. This can advantageously improve aerosol generation, particularly when an aerosol-generating article including a hollow tubular aerosol-forming substrate is inserted into the heating chamber 14.

[0072] Figures 2a-2f show individual susceptors 16, 18 of the two sets of susceptors of the heater assembly 10 of Figures 1a and 1b. Each susceptor 16, 18 of both the first and second sets of susceptors 16, 18 is elongated along the longitudinal axis of the heating chamber.

[0073] Figures 2a-2c show front, side, and top views, respectively, of a susceptor 16 of a first set of susceptors. The front view of Figure 2a shows a susceptor 16 including a stem 40, a heating surface 42, and a tip 44. In the heater assembly of Figures 1a and 1b, the distal end of each susceptor 16 is attached to a common support base 30 at the stem 40. When an aerosol-generating article is inserted into the heating chamber 14, the heating surface 42 is in intimate thermal contact with the aerosol-forming substrate of the aerosol-generating article.

[0074] The side view of Figure 2b and the top view of Figure 2c show that the tips 44 are beveled, which creates a flared shape at the proximal ends of the first circumferentially disposed set of susceptors 16 that facilitates insertion of an aerosol-generating article.

[0075] 2d-2f show front, side, and top views, respectively, of the susceptors 18 of the second set of susceptors. The susceptors 18 of the second set of susceptors are longer than the susceptors 16 of the first set of susceptors, measured parallel to the longitudinal axis of the heating chamber. The front view of FIG. 2d shows the susceptors 18 of the second set of susceptors 18, including a thinner distal portion and a wider proximal portion. The susceptors 18 form a paddle-like shape. The susceptors 18 include a stem 46, a curved portion 48, a heating surface 50, and a tip 52. In the heater assembly of FIGS. 1a and 1b, the distal end of each susceptor 18 is attached to the common support base 30 at the stem 46. The curved portion 48 has a curved shape along the longitudinal axis of the heating chamber. This results in a laterally protruding portion. The curved form of portion 48 is shown in side view in Figure 2e. In the assembled state, portion 48 is curved away from the central longitudinal axis of the heating chamber. The S-shape of susceptor 18 along the longitudinal axis of heating chamber 14 is shown, whereby when the aerosol-generating article is inserted into heating chamber 14, only heating surface 50 is in intimate thermal contact with the aerosol-forming substrate of the aerosol-generating article. Second susceptor 18 advantageously does not contact, and therefore does not heat, the aerosol-generating article in the region of first heating zone 20.

[0076] The side view of Figure 2e and the top view of Figure 2f show that the tips 52 are beveled, which provides a circumferentially disposed set of flared shapes for the second susceptor 18 that facilitates insertion of the aerosol-generating article.

[0077] FIG. 3 visualizes the alternating arrangement of the first and second susceptors 16, 18 in the heater assembly of FIGS. 1a and 1b. Each susceptor 16 of the first set is adjacent to two susceptors 18 of the second set. FIG. 3 also shows that the heating surfaces 42, 50 of the susceptors 16, 18 of the first and second sets of susceptors are arranged in a honeycomb pattern. FIG. 3 also shows the gaps between the individual susceptors. For ease of presentation, FIG. 3 shows the susceptors 16, 18 in a planar arrangement instead of the circumferential arrangement about the central axis 12 in the assembled state of FIGS. 1a and 1b.

[0078] Due to the elongated shape of the susceptor and the fact that the susceptor is attached to the common support base 30 by its stems 40, 46, the susceptor is flexible in the transverse direction, particularly at its tips 44, 52. This spring-like flexibility of the susceptors 16, 18 facilitates the insertion of the aerosol-generating article into the heating chamber 14. The flexible susceptors 16, 18 also improve gripping and securely hold the inserted aerosol-generating article. Before the aerosol-generating article is inserted into the heating chamber 14, the distance between the heating surfaces 42, 50 and the closest point of the central axis 12 may be less than the diameter of the aerosol-generating article. However, once the aerosol-generating article is inserted into the induction heating chamber 14, the spring-like properties of the susceptors 16, 18 push them laterally away from the central axis 12, allowing the aerosol-generating article to be held in place without penetrating the aerosol-generating article. Thus, the heater surfaces 42, 50 hold the aerosol-generating article firmly by pushing laterally against it, providing intimate thermal contact, while at the same time the aerosol-generating article may be gently removed from the heating chamber 14 by pulling it along the longitudinal axis 12. This may be further facilitated by the heater surfaces 42, 50 being configured to have a low coefficient of friction.

[0079] 4a shows an aerosol-generating article 54 for use in an aerosol-generating device comprising a heater assembly of the present invention. The aerosol-generating article 54 comprises a hollow cylindrical tube with two portions 56, 58 of a solid aerosol-forming substrate at its distal end and a mouthpiece including a mouthpiece filter (not shown) at its proximal end 60.

[0080] Figure 4b shows the aerosol-generating article 54 of Figure 4a being inserted into the heating chamber 14 of the heater assembly 10 of Figures 1a and 1b. The distal end of the aerosol-generating article 54 is inserted into the heating chamber 14 such that the hollow cylindrical tube of the aerosol-generating article 54 is circumferentially surrounded by the susceptor arrangement.

[0081] A first portion of the aerosol-forming substrate 56 is surrounded by, and in intimate thermal contact with, the heated surfaces 42 of the susceptors 16 of the first set of susceptors. The first portion of the aerosol-forming substrate 56 is disposed in the first heating zone 20. A second portion of the aerosol-forming substrate 58 is surrounded by, and in intimate thermal contact with, the heated surfaces 50 of the susceptors 18 of the second set of susceptors. The second portion of the aerosol-forming substrate 58 is disposed in the second heating zone 22.

[0082] During use, air may enter the air inlet 34 and then propagate laterally between the susceptors 16, 18 and into the aerosol-forming substrates 56, 58. The formed aerosol may then propagate laterally into the hollow core of the aerosol-generating article 54 and then longitudinally towards the mouthpiece at the proximal end 60 of the aerosol-generating article 54 where the aerosol may be inhaled by a user.

Claims

1. 1. A heater assembly for an aerosol generating device, comprising: a heating chamber for heating the aerosol-forming substrate; a first set of two or more susceptors configured to heat a first heating zone of the heating chamber; a second set of two or more susceptors configured to heat a second heating zone of the heating chamber; A heater assembly, wherein the first heating zone and the second heating zone are disposed at different longitudinal positions of the heating chamber.

2. 10. The heater assembly of claim 1, wherein one or both of the susceptors of the first and second sets are elongated along a longitudinal axis of the heating chamber.

3. 3. The heater assembly of claim 1 or claim 2, wherein one or both of the first and second sets of susceptors are circumferentially disposed around the heating chamber.

4. 4. The heater assembly of claim 3, wherein the susceptors of the first set of susceptors and the susceptors of the second set of susceptors are arranged in an alternating manner such that a susceptor of the first set is adjacent to two susceptors of the second set.

5. 5. A heater assembly as described in any one of claims 1 to 4, wherein one or both of the susceptors of the first and second sets are flexible in a direction perpendicular to a longitudinal axis of the heating chamber to securely hold an aerosol-generating article after insertion into the heating chamber.

6. 6. The heater assembly of claim 1, wherein at least a portion of one or both of the susceptors of the first and second sets includes a curved shape along a longitudinal axis of the heating chamber.

7. 7. The heater assembly of claim 1, wherein the susceptors of the second set of susceptors are longer than the susceptors of the first set of susceptors as measured parallel to a longitudinal axis of the heating chamber.

8. 8. The heater assembly of claim 1, wherein the susceptors of the second set of susceptors include a thinner distal portion and a wider proximal portion, the term proximal referring to a direction closer to a user in use and the term distal referring to a direction away from a user in use.

9. The heater assembly of any of claims 1 to 8, wherein the susceptors of the second set of susceptors form a paddle-like shape.

10. The heater assembly of any of claims 1 to 9, wherein a gap is provided between the heating surfaces of the susceptors of the first set of susceptors and the heating surfaces of the susceptors of the second set of susceptors.

11. A heater assembly according to any preceding claim, wherein gaps are provided between the heating surfaces of the susceptors within a set of susceptors.

12. The heater assembly of any preceding claim, wherein a susceptor shape of the first set of susceptors is different from a susceptor shape of the second set of susceptors.

13. The heater assembly of any of claims 1 to 12, wherein the first and second sets of susceptors are mounted on a common base disposed at a distal end of the heating chamber.

14. An aerosol generating device comprising a heater assembly according to any one of claims 1 to 13.

15. 15. An aerosol generation system comprising an aerosol generating device according to claim 14 and an aerosol-generating article comprising an aerosol-forming substrate, the aerosol-generating article being configured to be at least partially inserted into the heated chamber.

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