Aerosol generating device having multiple identical ring-shaped susceptors

Abstract

The present invention relates to an aerosol generating device comprising: a cylindrical heating cavity (6) extending mainly in the axial direction for receiving a vaporizable stick containing a substance suitable for vaporizing upon heating to generate an inhalable vapor; a heater (8) at least partially surrounding the cylindrical heating cavity; and a magnetic field generator (9, 12) configured to generate a variable magnetic field through the heater to heat the heater by induction, characterized in that the heater comprises a plurality of identical ring-shaped susceptors (8) arranged along the axial direction, each ring-shaped susceptor (8) surrounding the cylindrical heating cavity (6). Such segmented heaters can provide either uniform heating of the entire stick or a temperature distribution along the axial direction for selectively heating portions of the stick.

Description

[Technical Field]

[0001] The present disclosure relates to aerosol generating devices, such as heated tobacco devices, that produce inhalable vapor by heating, without combustion, a stick containing tobacco and / or other substrate suitable for conversion to inhalable vapor upon heating. [Background technology]

[0002] The aerosol generating device generally includes a box containing a microcontroller, a user interface for communicating with the microcontroller, a battery, an atomizer including a chamber for receiving a vaporizable stick (e.g., a stick containing tobacco) made of a substance suitable for heating to generate inhalable vapor, and an electric heater powered by the battery and controlled by the microcontroller for heating the stick by conduction, convection and / or radiation.

[0003] The vaping experience is determined by various parameters, such as the maximum power delivered by the battery to the heater, the maximum temperature of the heater, ramp-up (the rise time to reach the desired maximum temperature), inlet airflow, etc. These parameters can be set differently depending on the substrate to be vaporized and / or the material used and / or the user's mood and desires. Vaping devices can be controlled according to various modes, such as a temperature mode in which a microcontroller controls the temperature of the heater and adjusts the power delivered to the heater according to the heater's current temperature to reach a temperature setpoint value.

[0004] When the tobacco device is turned on, it may be desirable to heat the sticks quickly to avoid long wait times before vaping can begin, and then to heat the sticks at a steady, low temperature to allow vaping over an extended period of time.

[0005] For this reason, it is desirable to be able to vary the temperature of any part of the stick over time, or to vary the average temperature of the stick over time.

[0006] It may also be desirable to be able to locally vary the temperature of parts of the stick, or to vary the distribution of heat within the stick.

[0007] For various reasons, it may also be desirable to locally heat the stick or to be able to selectively heat portions of the stick.

[0008] On the other hand, it may also be desirable to heat the entire stick evenly at a particular moment or over an extended period of time.

[0009] In summary, it is desirable to provide a heated tobacco device having an easily adjustable heater.

[0010] Other known aerosol generating devices include heaters that are heated by induction. International Publication No. WO2017036955 discloses an example of a heated tobacco device that uses an inductively heated heater element.

[0011] The induction heating tobacco device of the pamphlet of WO2017036955 does not allow for a variable temperature distribution within the tobacco stick, particularly along the axial direction of the stick. Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention aims to solve at least one of the above problems using a simple configuration that is easy to implement, compact, and control. [Means for solving the problem]

[0013] The present invention provides an aerosol generating device, comprising: - a cylindrical heating cavity extending mainly in the axial direction for receiving a vaporizable stick containing a substance suitable for being vaporized upon heating to generate an inhalable vapor; a heater at least partially surrounding the cylindrical heating cavity; a magnetic field generator configured to generate a variable magnetic field through the heater to heat the heater by induction; The present invention proposes an aerosol generating apparatus including the heater, characterized in that the heater includes a plurality of identical ring-shaped susceptors arranged along the axial direction, each ring-shaped susceptor surrounding a cylindrical heating cavity.

[0014] In other words, the heater includes a segmented susceptor configuration consisting of a series of identical ring-shaped susceptors that are optimized for efficient induction heating and, because they are identical, can generate uniform heating, thereby avoiding localized overheating.

[0015] On the other hand, a ring-shaped susceptor can provide a temperature gradient along the axial direction of the stick, allowing for cold and hot spots within the stick while avoiding hot spots that are detrimental to the vaporizable material.

[0016] Thus, the aerosol generating device can be used with a stick consisting of successive identical or different sections, each section corresponding to one (or possibly two) ring-shaped susceptors.

[0017] In particular, the aerosol generating device can be used with multi-section tobacco sticks having different components made of different tobacco materials that require preferential heating at different frequencies and therefore different temperatures for vaporization. In this way, users may enjoy different flavor experiences with a single stick. Such sticks can be heated throughout with a temperature distribution that exhibits different temperatures in each of the different sections of the stick. Alternatively, where possible or desired, the stick can be heated throughout with a uniform temperature distribution (i.e., the same temperature throughout the stick), which is possible because the ring-shaped susceptor is identical.

[0018] As another example, a stick may consist of multiple identical or non-identical sections, intended to be heated at different times, to provide a long-lasting sensory experience, or a user may not wish to vape the entire stick at once and may vape only a portion of the stick with the intention of vaping another portion later, where only one or more sections may be heated. All of the sections of the stick may thus be heated sequentially, either at the same temperature or at different temperatures (by adapting the magnetic field provided by the generator).

[0019] It should be noted that the aerosol generating device according to the present invention can be used with vaporizable sticks, also known as "consumable parts." Such consumable parts include solid sticks, i.e., sticks made of solid vaporizable material. These roughly resemble traditional cigarettes, with a tubular region in which the vaporizable material is arranged in an appropriate manner. Some designs may also include filters, vapor collection regions, cooling regions, and other structures. For example, an outer layer of paper or other flexible, flat material, such as foil, may also be provided to hold the solid vaporizable material in place, further enhancing the similarity to a traditional cigarette.

[0020] However, the present invention is not limited to such consumable parts. It can be used with any stick made of vaporizable material. In this case, the expression "vaporizable material" denotes any material that can be vaporized in air to form an aerosol. Vaporization is generally achieved by raising the temperature up to a temperature corresponding to the boiling point of the vaporizable material, in particular up to a temperature of 400°C, preferably up to 350°C. The vaporizable material can, for example, comprise or consist of tobacco derivatives, expanded tobacco, tobacco extracts, homogenized tobacco, tobacco substitutes, or any combination thereof, and it can also comprise or consist of aerosol-generating liquids, gels, waxes, etc.

[0021] Thus, the aerosol generating device according to the invention can be used not only with sticks made of solid vaporizable material, but also with sticks containing liquids or gels etc., which liquids or gels are, for example, held in a solid matrix or contained in pods forming the entire stick or forming sections of the stick (in this case the stick may contain a combination of a solid section and a liquid or viscous section in the form of a pod filled with liquid or viscous vaporizable material).

[0022] In addition, as will be explained better in the detailed description, the present invention applies not only to aerosol generating devices configured to receive solid sticks of the type including a mouthpiece or similar to conventional cigarettes as described above, but also to aerosol generating devices configured to receive vaporizable sticks of the pod or capsule or tablet type without a mouthpiece (in this second case, the aerosol generating device includes a mouthpiece fixedly or removably attached to the atomizing portion of the aerosol generating device). In other embodiments, the heating cavity can be arranged to receive vaporizable sticks in other forms, such as loose or otherwise packaged tobacco.

[0023] According to a possible feature, the ring-shaped susceptors have an inner diameter smaller than the outer diameter of the cylindrical heating cavity, so that each ring-shaped susceptor exerts pressure on a vaporizable stick received in the cylindrical heating cavity.

[0024] Alternatively or additionally, the ring-shaped susceptor has internal protrusions on its inner surface for applying compression to the vaporizable stick received in the cylindrical heating cavity.

[0025] Alternatively or additionally, the ring-shaped susceptor has a convex inner surface, thereby presenting a variable inner diameter, the smallest inner diameter of which is smaller than the outer diameter of the cylindrical heating cavity. Again, such a ring-shaped susceptor applies pressure to the vaporizable stick received in the cylindrical heating cavity.

[0026] In all these alternative embodiments, applying compression to the vaporizable stick helps lock the vaporizable stick in place and prevent slippage, which also optimizes thermal contact / transfer between the ring-shaped susceptor and the vaporizable stick.

[0027] According to a possible feature, the ring-shaped susceptors have convex upper or lower edges to create a temperature gradient within each ring-shaped susceptor.

[0028] According to a possible feature, the ring-shaped susceptors are spaced apart from one another in the axial direction by the same spacing distance.

[0029] Alternatively, the ring-shaped susceptors are spaced apart from one another along the axial direction at different spacing distances, which results in an axial temperature gradient along the axial direction within the cylindrical heating cavity when the susceptors are all heated simultaneously and equally by the magnetic field generating device.

[0030] According to a possible feature, the ring-shaped susceptor has a width and a height in the axial direction that is greater than the thickness of the ring-shaped susceptor in the radial direction.

[0031] Throughout this specification, the expression "susceptor width" refers to the axial dimension of the ring-shaped susceptor, i.e., the axial distance between the upper and lower edges of the susceptor. If the ring-shaped susceptor has a convex upper or lower edge, the width of the susceptor is the maximum axial distance between the upper and lower edges. The expression "susceptor height" refers to the distance between the cross-section containing the highest point of the susceptor and the cross-section containing the lowest point of the susceptor, the cross-section being a plane perpendicular to the axial direction.

[0032] The width and height of a susceptor can be the same, for example, when the lower and upper edges of the susceptor extend in parallel cross-sections. The width and height of a susceptor can be different, for example, when the ring-shaped susceptor is in the shape of a corrugated ring as described later in this specification. In the case of a susceptor that is a corrugated ring having parallel upper and lower edges corrugated with peaks and valleys, the width is the (axial) distance between the parallel edges at any point, i.e., the axial distance between, for example, the valley of the upper edge and the valley of the opposing lower edge (or, similarly, between the peak of the upper edge and the peak of the opposing lower edge). The height of such a corrugated ring susceptor is the axial distance between the cross-section including the peak (or highest peak) of the upper edge and the cross-section including the valley (or lower valley) of the lower edge. Therefore, in such a corrugated ring susceptor, the height of the susceptor is greater than the width of the susceptor.

[0033] In one possible embodiment, there are six ring-shaped susceptors, each having an axial width of about 2-3 mm and a radial thickness of about 0.1-0.3 mm, and the ring-shaped susceptors are preferably spaced apart from each other at equal axial spacing distances of 0.5-1 mm.

[0034] According to a possible feature, the ring-shaped susceptors are connected together by a plurality of insulating axial rods fixed to the outer surface of the ring-shaped susceptors, in which case the spacing distance between two successive susceptors cannot be varied.

[0035] According to a possible feature, at least one of the ring-shaped susceptors is arranged to be movable along an axial direction to selectively heat portions of the cylindrical heating cavity, the other susceptors being connected together, or not, by insulating rods.

[0036] According to a possible feature, the aerosol generating device includes means for axially displacing the vaporizable stick received in the cylindrical heating cavity, and for this purpose the aerosol generating device may include a member adapted to engage the vaporizable stick and to be operated automatically or manually by a user to displace the vaporizable stick along the axial direction of the cylindrical heating cavity.

[0037] According to a possible feature, the magnetic field generator of the heated tobacco device is configured to heat all of the ring-shaped susceptors simultaneously, for example, the magnetic field generator includes a coil having an axial height sufficient to surround all of the ring-shaped susceptors, so that all of the susceptors are heated simultaneously when a variable current is supplied to the coil.

[0038] Alternatively, the magnetic field generating device of the heated tobacco device is configured to heat only some of the ring-shaped susceptors simultaneously to provide a variable heating distribution along the length (i.e., axially) of the tobacco stick.

[0039] For this purpose, the magnetic field generating device may be, for example: - a tubular housing configured to surround the cylindrical heating cavity and the ring-shaped susceptor, an upper portion of the tubular housing supporting a coil that extends axially along only a portion of the (axial) length of the cylindrical heating cavity, the tubular housing further having a threaded inner surface; - a stationary motor having a shaft that drives a threaded nut coupled to the threaded inner surface of the tubular housing, whereby rotation of the nut causes axial movement of the tubular housing; Includes:

[0040] Due to the tubular housing, motor and nut, the coil is movable along the axial direction (towards the upper or lower end of the cylindrical heating cavity depending on the rotation of the nut), so that the coil is first positioned at the height of one or more susceptors and then moves along the axial direction to face one or more other susceptors, thereby allowing different parts of the tobacco stick to be heated successively.

[0041] According to a first embodiment, the ring-shaped susceptor is simply a truncated cylinder with flat, preferably parallel, upper and lower edges.

[0042] According to a second embodiment, the ring-shaped susceptor is formed of a closed corrugated ring having corrugated (non-flat) upper and lower edges with peaks and valleys, which are preferably parallel.

[0043] According to a possible feature, all or some of these wave rings come into contact with one another to form a multi-turn wave set, which makes it possible to create zones of different temperatures within the cylindrical heating cavity, with a hot area being provided where two wave rings come into contact with one another.

[0044] According to a possible feature, the corrugated ring has a width large enough that the crests of the waves at the lower edge are located axially below the troughs of the waves at the upper edge, and the corrugated ring thus exhibits a flat, straight central band in which, when the corrugated ring is energized, rapid and efficient heat delivery by induction heating is achieved, and then, when the corrugated ring is de-energized, heat flow from the central band to the edges of the corrugated ring achieves heat distribution over a larger surface area.

[0045] According to a possible feature, the ring-shaped susceptor, whatever its shape (truncated cylinder or corrugated ring), is made of low-carbon steel, which allows a very efficient energy transfer (when converting the electromagnetic field into heat).

[0046] Other particularities and advantages of the present invention will become apparent from the following description.

[0047] The accompanying drawings, given as non-limiting examples, are: [Brief explanation of the drawings]

[0048] [Figure 1] 1 shows a side view of an aerosol generating device according to a first embodiment of the present invention. [Figure 2] 2 shows a schematic axial cross section of the first embodiment of FIG. 1, with the coils of the magnetic field generating device at their highest position; [Figure 3] 3 shows a schematic axial cross section of the first embodiment of FIGS. 1 and 2, with the coils of the magnetic field generating device in their lowest position; [Figure 4] 1 shows an axial cross section of a first embodiment of a ring-shaped susceptor according to the invention. [Figure 5] 2 shows an axial cross section of a second embodiment of a ring-shaped susceptor according to the invention. [Figure 6] 3 shows an axial cross section of a third embodiment of a ring-shaped susceptor according to the invention. [Figure 7] 10 shows an axial cross section of a fourth embodiment of a ring-shaped susceptor according to the invention. [Figure 8] 10 shows an axial cross section of a fifth embodiment of a ring-shaped susceptor according to the invention. [Figure 9] 9 shows a side view of the assembly of the ring-shaped susceptor according to FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0049] The aerosol generating device according to the present invention shown in Figures 1 to 3 includes a control and power supply unit 1, an atomizing unit 2, a cap 3, a mouthpiece 4 that a user can place their mouth over to vape, and a base 5.

[0050] The control and power supply 1 houses several electronic components, including a battery 11 (see Figures 2 and 3) and a microcontroller 10 in the form of a main printed circuit board assembly. The microcontroller 10 is connected to the battery 11 and is powered by the battery in the conventional manner (schematically represented by connecting wires). At the lower end of the control and power supply 1, the base 5 may include connection means (not shown) for connecting the battery 11 to a suitable transformer or charger (not shown) powered by a USB (Universal Serial Bus) socket.

[0051] The atomizing portion 2 includes a heated cylindrical cavity 6 for receiving a vaporizable stick. The heated cylindrical cavity 6 is open at the upper end of the atomizing portion 2 when the cap 3 is removed so that a user can engage a stick 7 in the heated cylindrical cavity 6. This can be seen in Figures 2 and 3, where the cap 3 and mouthpiece 4 are omitted (the base 5 is also omitted in these two figures). In other embodiments, the cap 3 can also include a mouthpiece. In other words, the cap can constitute the mouthpiece. In Figure 1, the mouthpiece 4 is off-center; in some embodiments, the mouthpiece 4 can be located in the center of the cap, i.e., longitudinally aligned with the heated cavity.

[0052] It should be noted that the stick 7 illustrated in Figures 2 and 3 is in the form of a pod in which vaporizable material is embedded. The present invention is not limited to this type of stick. It also applies to solid sticks, in particular tobacco sticks similar to conventional cigarettes that already include a mouthpiece as described above. In such solid sticks, the upper end of the stick serves as or comprises the mouthpiece. In such cases, the aerosol generating device according to the present invention does not have the mouthpiece 4 as illustrated; instead, the cap 3 is provided with a central opening through which the upper end of the stick (mouthpiece) can penetrate and protrude, allowing the user to vape.

[0053] The aerosol generating device further includes a heater in the atomizing section 2. According to the present invention, the heater includes a plurality of identical ring-shaped susceptors 8 made of a conductive material such as a metallic material or low-carbon steel, surrounding the heated cylindrical cavity 6. In the example illustrated in Figures 2 and 3, the heater includes six closed ring-shaped susceptors, which are spaced apart from each other by the same spatial distance and connected and fixed within the atomizing section 2 by a plurality (e.g., four) insulating rods 19.

[0054] The ring-shaped susceptor is preferably closed and uninterrupted, since any interruptions would induce electrical arcing, which appears undesirable. Furthermore, the ring-shaped susceptor is preferably constructed without any change in electrical resistance to its outer surface to provide a continuous current path and ensure uniform energy flow within the susceptor. Any break in the current path would reduce the energy delivered as heat. A sudden change in resistance at a certain point would result in large-scale localized overheating, which would act like a fuse and burn out at that point (especially with thin materials).

[0055] The heater of the aerosol generating device herein further comprises a variable magnetic field generator including a coil 9 housed within an insulating tubular housing 14 that surrounds a ring-shaped susceptor 8 with insulating rods 19. The coil 9 is powered by an alternative current delivery component 12 controlled and supplied by a microcontroller 10.

[0056] In the illustrated example, the coil 9 does not extend axially along the entire length of the heating cylindrical cavity 6, but only along a portion thereof so as to face only two or three susceptors 8. In addition, the tubular housing has a threaded inner surface 17, and the heater further includes a motor 15 and a nut 16 having a threaded outer surface 18 that can engage with the threaded inner surface 16 of the tubular housing. The nut 16 is attached to the shaft of the motor 15, which is fixed within the aerosol generating device. Thus, operation of the motor 15 rotates the nut 16, thereby axially moving the tubular housing 14 and the coil 9. The tubular housing 14 and the coil 9 are shown in their highest positions in FIG. 2 and their lowest positions in FIG. 3.

[0057] In the accompanying drawings, the tubular housing has a double wall (i.e., an inner wall whose inner surface 17 is threaded and an outer wall whose surface is cylindrical), and the coil is housed inside the double wall. Alternatively, the tubular housing may be made of a single wall with a threaded inner surface in its lower part, and the coil may be fixed to the upper part of the outer surface of this single wall.

[0058] The control and power supply 1 may include one or more temperature sensors for measuring the temperature at various spots around the heated cylindrical cavity 6 along the axial direction, including a temperature sensor 13 configured to measure the temperature at the lower end of the heated cylindrical cavity. These means may be used to control the movement of the tubular housing 14 to adapt the position of the coil in real time according to the current distribution of the temperature within the heated cylindrical cavity 6 along the axial direction. Alternatively, the coil 9 may be moved according to a pre-programmed pattern, which may depend on the nature of the vaporizing stick present in the cavity, or which may be selected by the user from a variety of suggested patterns corresponding to different vaping experiences.

[0059] 4 to 8 show different types of ring-shaped susceptors that are suitable for implementing the present invention.

[0060] The ring-shaped susceptor 8 depicted in Figure 4 (and in Figures 2 and 3) is simply a truncated cylinder with a circular cross section, an upper edge 81 included in a first cross section, and a lower edge 82 included in a second cross section. The upper and lower edges are therefore flat and parallel. The ring-shaped susceptor has a thickness T in the radial direction, which is smaller than the axial width W of the susceptor.

[0061] The ring-shaped susceptor depicted in FIG. 5 is also a truncated cylinder with a circular cross section, but it has a convex upper edge 83 and a convex lower edge 84 .

[0062] The ring-shaped susceptor shown in Fig. 6 has a cylindrical outer surface and, like the ring-shaped susceptor 8 shown in Fig. 4, an upper edge 81 included in a first cross-section and a lower edge 82 included in a second cross-section. However, in contrast to this susceptor, the ring-shaped susceptor of Fig. 6 has a convex inner surface 86 that is expected to exert pressure on the vaporizable stick.

[0063] Like the ring-shaped susceptor 8 represented in Fig. 4, the ring-shaped susceptor represented in Fig. 7 is a cylindrical truncated member with a circular cross section, with an upper edge 81 included in a first cross section and a lower edge 82 included in a second cross section. However, contrary to the susceptor 8, the cylindrical inner surface of the ring-shaped susceptor represented in Fig. 7 is provided with protrusions 87 that locally apply compression to the vaporizable sticks.

[0064] 8 is a corrugated ring having cylindrical outer and inner surfaces and having parallel corrugated upper and lower edges 88 and 89 having peaks 91, 93 and valleys 90, 92. All of the peaks 91 of the upper edge 88 are included in the first cross-section, and all of the valleys 90 of the upper edge 88 are included in the second cross-section. Similarly, all of the peaks 93 of the lower edge 89 are included in the third cross-section, and all of the valleys 92 of the lower edge 89 are included in the fourth cross-section.

[0065] The width W of the corrugated ring is the axial distance (at any axial cross section) between the upper edge 88 and the lower edge 89. The height H of the corrugated ring is the distance between the first cross section (including the peak 91 of the upper edge 88) and the fourth cross section (including the valley 92 of the lower edge 89). Preferably, the width W of the corrugated ring is greater than its thickness (radial dimension). In fact, the thicker the corrugated ring, the greater its thermal mass. Therefore, a thicker ring requires more energy to heat to the same temperature as a thinner ring. Not only that, but thicker rings also require longer heating times, which is generally undesirable. Additionally, a moderately large width provides an optimal electric field path for induction heating and maximizes the contact surface area with the vaporizable stick.

[0066] Advantageously, the valleys 90 of the upper edge 88 are located above the peaks 93 of the lower edge 89, thereby providing a flat, straight central band B (axially) extending between the second cross-section (including the valleys 90 of the upper edge 88) and the third cross-section (including the peaks 93 of the lower edge 89) where rapid and efficient heat delivery by induction heating is achieved when the corrugated ring is energized.

[0067] Figure 9 shows an assembly in which three corrugation rings 101-103 identical to the corrugation ring 100 of Figure 8 are positioned close to one another to form multi-turn corrugations in which the valleys 92 of the lower edge of the first corrugation ring 100 contact the crests 91 of the upper edge of the second corrugation ring 101, resulting in contact points 94. Similarly, contact points 94 are provided by contacting the valleys of the lower edge of the second corrugation ring 101 with the crests of the upper edge of the third corrugation ring 102. In this manner, hot spots (but not burn spots) are provided at the contact points 94 within the tobacco stick.

[0068] An aerosol generating device including a plurality of corrugated rings 100 spaced apart from one another along a heated cylindrical cavity is in accordance with the present invention. An aerosol generating device including at least one multi-serpentine corrugated shape and one or more other corrugated rings spaced apart from one another and from the multi-serpentine corrugated shape, such as that illustrated in Figure 9, is also in accordance with the present invention. Similarly, an aerosol generating device including a plurality of multi-serpentine corrugated shapes spaced apart from one another is also in accordance with the present invention. Additionally, the multi-serpentine corrugated shape may include a multi-serpentine corrugated shape with an equal number of corrugated rings or a multi-serpentine corrugated shape that does not have an equal number of corrugated rings.

[0069] The invention extends to all alternative embodiments covered by the appended claims.

[0070] In particular, the axially movable coil 9 can be replaced by a fixed coil associated with means for axially moving the tobacco stick (manually or automatically). For example, the aerosol generating device can include a cylindrical cavity extending from the upper end of the aerosol generating device and having an axial length approximately twice the length of the tobacco stick 7. The cylindrical cavity exhibits an upper portion having a height as long as the length of the tobacco stick and a lower portion having a height approximately the length of the tobacco stick.

[0071] The cylindrical hollow is provided with a slide plate configured to receive the lower end of the tobacco stick and move axially within the cylindrical hollow. A tethering element can protrude from the upper surface of the slide plate and engage with the stick, such as to secure the stick to the slide plate. The slide plate is configured to be moved axially between its highest and lowest positions automatically or manually. When the slide plate is in its highest position, it is located at the junction between the upper and lower parts of the cylindrical hollow (in other words, it is located at the center height of the cylindrical hollow or slightly below the center height). When the slide plate is in its highest position, the tobacco stick fills the upper part of the cylindrical hollow (the upper end of the tobacco stick is flush with the upper end of the cylindrical hollow). When the slide plate is in its lowest position, it is located at the lower end of the cylindrical hollow, and the tobacco stick fills the lower part of the cylindrical hollow.

[0072] The fixed coil can be positioned directly above the junction between the upper and lower portions of the hollow cylinder to heat at least the lower portion of the tobacco stick when the slide plate is at its highest position. The hollow cylinder surrounded by the fixed coil corresponds to the cylindrical heating cavity described in the claims. When the slide plate moves downward, the fixed coil ends facing the upper portion of the tobacco stick and heats the upper portion. When the slide plate is at its lowest position, the fixed coil ends facing the upper end of the tobacco stick and heats the upper end.

[0073] Those skilled in the art can envision various embodiments for automatically moving the slide plate without taking any inventive steps, for example, the lower surface of the slide plate could be fixed to the end of a small piston extending axially in a hollow cylinder below the slide plate.

[0074] In the above example, the cylindrical hollow has a height greater than the cylindrical heating cavity 6 shown, so it may be necessary to house some of the elements that make up the control and power supply unit 1 elsewhere, for example above or near the stationary coil around the upper part of the cylindrical hollow.

[0075] Returning to the illustrated embodiment (where the tobacco stick does not move), it is also possible to provide a fixed coil extending along the entire length of the cylindrical heating cavity, or preferably multiple fixed coils, each facing one or two susceptors, which are independently connected to alternative current delivery members 12, such as to allow all coils to be powered simultaneously or only one of them. [Explanation of symbols]

[0076] 1 Power supply 2 Spray section 3 Cap 4 mouthpieces 5 base 6 Cylindrical heating cavity 7 Vaporizable Sticks 8 Ring-shaped susceptor 81 upper edge 82 bottom edge 83 (convex) top edge 84 (convex) bottom edge 86 (convex) inner surface 87 Protrusion 88 (wave-like) top edge 89 (wave) bottom edge 90 Upper edge valley 91 Top of upper edge 92 Lower edge valley 93 Top of bottom edge 94 contact points 9 coils 10 Microcontrollers 11 Battery 12 Current Delivery Components 13 Temperature Sensor 14 Tubular housing 15 motor 16 Nut 17 Inner surface of tubular housing 18 Outer surface of nut 19 Insulating rod 100~103 Wave Ring B Central Band

Claims

1. An aerosol generating device, comprising: a cylindrical heating cavity (6) extending mainly in the axial direction for receiving a vaporizable stick (7) containing a substance suitable for being vaporized when heated to generate an inhalable vapor; a heater (8, 100, 101-103) at least partially surrounding said cylindrical heating cavity; a magnetic field generator (9, 12) configured to generate a variable magnetic field through said heater (8) to heat said heater by induction; In an aerosol generating apparatus comprising: the heater includes a plurality of identical ring-shaped susceptors (8, 100-103) arranged along the axial direction, each ring-shaped susceptor (8) surrounding the cylindrical heating cavity (6); At least one of the ring-shaped susceptors (8, 100) is arranged to be movable along the axial direction. An aerosol generating device characterized by:

2. 2. The aerosol generating device according to claim 1, wherein the ring-shaped susceptor (8) has an inner diameter smaller than the outer diameter of the cylindrical heating cavity (6).

3. 3. The aerosol generating device according to claim 1, wherein the ring-shaped susceptor has an internal protrusion (87) on its inner surface.

4. 4. The aerosol generating device of claim 1, wherein the ring-shaped susceptor has a convex inner surface (86) thereby presenting a variable inner diameter whose minimum inner diameter is smaller than the outer diameter of the cylindrical heating cavity (6).

5. 5. An aerosol generating device according to any one of claims 1 to 4, wherein the ring-shaped susceptor has a convex upper or lower edge (83, 84).

6. 6. An aerosol generating device according to any one of claims 1 to 5, wherein the ring-shaped susceptors (8, 100) are spaced apart from one another at the same spacing distance in the axial direction of the cylindrical heating cavity.

7. 6. An aerosol generating device according to any one of claims 1 to 5, wherein the ring-shaped susceptors (8, 100) are spaced apart from one another along the axial direction at different spacing distances.

8. 8. An aerosol generating device according to claim 1, wherein the ring-shaped susceptor (8, 100) has a width (W) and a height (H) in the axial direction that are greater than the thickness (T) of the ring-shaped susceptor in the radial direction.

9. 9. The aerosol generating device according to claim 1, wherein the number of ring-shaped susceptors (8) is six, each having a width (W) of about 2 to 3 mm in the axial direction and a thickness (T) of about 0.1 to 0.3 mm in the radial direction, and the ring-shaped susceptors are spaced apart from each other at equal intervals of about 0.5 to 1 mm in the axial direction.

10. 10. An aerosol generating device according to any one of claims 1 to 9, wherein the ring-shaped susceptors (8) are connected together by a plurality of insulating axial rods (19) fixed to the outer surface of the ring-shaped susceptors.

11. An aerosol generating device as described in any one of claims 1 to 10, further comprising a member configured to engage with a vaporizable stick (7) received within the cylindrical heating cavity and to be operated to move the vaporizable stick along the axial direction within the cylindrical heating cavity (6).

12. The magnetic field generating device is a coil (9) extending axially along only part of the length of said cylindrical heating cavity (6); a tubular housing (14) configured to surround the cylindrical heating cavity (6) and the ring-shaped susceptor (8), the upper part of the tubular housing supporting the coil (9), the tubular housing (14) further having a threaded inner surface (17); a stationary motor (15) having a shaft that drives a threaded nut (16) that is coupled to the inner surface (17) of the tubular housing, whereby the rotation of the threaded nut (16) causes the tubular housing (14) to move axially together with the coil (9); 12. The aerosol generating device according to claim 1, comprising:

13. 13. An aerosol generating device according to any one of claims 1 to 12, wherein the ring-shaped susceptor is formed of a closed corrugated ring (100) having corrugated upper and lower edges (88, 89) each having peaks (91, 93) and valleys (90, 92).

14. 14. The aerosol generating device according to claim 13, wherein all or some of the corrugated rings (101-103) are in contact with each other to form multi-serpentine corrugations.

15. 15. An aerosol generating device as claimed in claim 13 or 14, wherein the wavy ring (100, 101-103) has a width (W) large enough that the crests (93) of the waves of the lower edge (89) are located below the troughs (90) of the waves of the upper edge (88) in the axial direction, and the wavy ring therefore exhibits a flat, straight central band (B).

16. 16. An aerosol generating device according to any one of claims 1 to 15, wherein the ring-shaped susceptor (8, 100, 101 to 103) is made of low carbon steel.

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