WO2025017184A1

WO2025017184A1 - Uniform em field in ih heat-not-burn devices

Info

Publication number: WO2025017184A1
Application number: PCT/EP2024/070561
Authority: WO
Inventors: John MEUTHEN; Tilen CEGLAR
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2023-07-20
Filing date: 2024-07-19
Publication date: 2025-01-23
Anticipated expiration: 2026-01-20

Abstract

The invention relates to an aerosol generating device for heating an aerosol generating article, comprising an inductive coil comprising a plurality of turns and configured to provide an electromagnetic field within a receiving volume configured to receive the aerosol generating article. The inductive coil comprising one or more first areas and two or more second areas, wherein the one or more first areas are arranged between at least two of the two or more second areas in a longitudinal direction of the inductive coil, wherein the diameter of the turns of the coil is larger in the one or more first areas than in the two or more second areas. The invention also relates to an aerosol generating assembly comprising the aerosol generating device and a susceptor, preferably included in the aerosol generating article.

Description

UNIFORM EM FIELD IN IH HEAT-NOT-BURN DEVICES

TECHNICAL FIELD

The present invention relates to an aerosol generating device for heating an aerosol generating article and to an assembly comprising a susceptor and the aerosol generating device.

BACKGROUND

An aerosol generating device, or E-cigarette, is now a mainstream product to simulate a traditional tobacco cigarette. There are many types of aerosol generating devices, one of them having an operation method which is to heat a tobacco product to generate an aerosol without causing the tobacco to burn. These so-called heat-not-burn (HNB) devices are increasingly popular.

The heat-not-burn devices generally operate with a tobacco article that is inserted into the device and heated by a heating element comprised in the heat-not-burn device. Various tobacco articles are commercially available. In recent years, two main forms of heating the tobacco are commonly used, resistive heating elements and inductive heating elements.

Due to spatial confinement reasons, typically, in aerosol generating devices, short coils are typically used for the inductive heating assembly. The assembly consists of a coil (inductor) and a piece of ferromagnetic metal (susceptor) in various shapes, typically a stripe. The inductor applies an electromagnetic field that induces eddy currents in the susceptor. The eddy currents in the susceptor heat up the susceptor. By placing the susceptor in proximity of or even inside the tobacco product, the heat transfers into the tobacco product heating up the tobacco until an aerosol is formed. Existing devices typically have a fixed blade as susceptor or a loose susceptor incorporated by the tobacco consumable.

Due to the special limitations, only short solenoid coils can be used that typically form an inhomogeneous B-field. Due to the inhomogeneous nature of the B-field, the energy induced into the susceptor highly depends on the position of the susceptor relative to the coil. With such an inhomogeneous B-field, the achieved temperature at constant parameters (e.g., PWM duty cycle) used for the coil may lead to non-consistent heating of the susceptor, depending on the susceptor’s position. Accordingly, the tobacco product may either not be heated enough or overheated if the susceptor acting as the heating element does not have the right temperature.

It is therefore desired to provide an aerosol generating device with an inductive heating system that has the above-described benefits but avoids any of the above inconveniences by forming a homogeneous electromagnetic field.

One or more of these objects are achieved by the subject-matter of the independent claims. Preferred embodiments are subject of the dependent claims.

SUMMARY OF THE INVENTION

The present invention provides a device which solves some or all of the above problems.

In an aspect, the present invention is directed to an aerosol generating device for heating an aerosol generating article, comprising an inductive coil comprising a plurality of turns and configured to provide an electromagnetic field within a receiving volume configured to receive the aerosol generating article. The inductive coil comprising one or more first areas and two or more second areas, wherein the one or more first areas are arranged between at least two of the two or more second areas in a longitudinal direction of the inductive coil, wherein the diameter of the turns of the coil is larger in the one or more first areas than in the two or more second areas.

By arranging the one or more first areas between the two or more second areas, a more homogeneous electromagnetic field is formed inside the coil, when compared to a coil without changing diameter. This allows to heat up the susceptor inside the receiving volume more evenly, preventing over-/underheating of the tobacco product and increasing the effectiveness of the heater assembly. Moreover, extensive calibration processes for finding proper heating parameters and precise position inside the receiving volume for the aerosol generating article can be omitted.

In a further aspect, the diameter of the turns of the coil in the one or more first areas has at most 15% variance in diameter, preferably at most 10% variance in diameter, more preferably at most 5% variance in diameter and most preferably substantially no variance in diameter and/ or the diameter of the turns of the coil in the two or more second areas has at most 15% variance in diameter, preferably at most 10% variance in diameter, more preferably at most 5% variance in diameter and most preferably substantially no variance in diameter.

By arranging the coil in this manner, the susceptor may be heated up even more evenly.

In another aspect, the diameter of the turns of the coil in the one or more first areas is at least 3% larger, preferably at least 5% larger, more preferably at least 7% larger and most preferably at least 10 % larger than the diameter of turns of the coil in the two or more second areas.

In a further aspect, in longitudinal direction of the inductive coil, the one or more first areas cover at least 50%, preferably at least 60%, more preferably at least 70%, even more preferably at least 80% and most preferably at least 90% of the length of the inductive coil, and/or preferably, in longitudinal direction of the inductive coil 110, the two or more second areas cover at least 5%, preferably at least 10%, more preferably at least 15%, even more preferably at least 20% and most preferably at least 30% of the length of the inductive coil.

In yet another aspect, the two second areas are preferably arranged at a distal end of the inductive coil and at a proximal end of the inductive coil.

Experiments have shown that the above dimensions and arrangement of the coil in the first area and the second area provide the most homogeneous electromagnetic field, resulting in the most efficient heating of the susceptor.

In another aspect, the inductive coil comprises only one first area and two second areas.

In a further aspect, the inductive coil comprises only one first area and two second areas, wherein a first side of the first area is located at a first side of one of the two second areas and a second side of the first area opposite to the first side is located on a first side of the second of the two second areas, wherein the one first area and the two second areas preferably form a trapezoidal shape.

In a further aspect, the induction coil is a single layer coil.

In yet another aspect, the induction coil is a multi-layer coil.

In another aspect, the induction coil is formed by a single wire. In yet another aspect, the wire forming the induction coil has a cross-sectional area with at most 15% variance in diameter, preferably at most 10% variance in diameter, more preferably at most 5% variance in diameter and most preferably substantially no variance in diameter in at least 70 %, preferably at least 80% more preferably at least 90% and most preferably in at least 95% of the length of the wire in the one or more first areas and/or in the two or more second areas.

In another aspect, an aerosol forming material is homogenously distributed in the aerosol generating article.

By providing the aerosol generating material (such as tobacco material) in a homogenous manner, the aerosol generating article may be consumed in an even manner. This reduces waste of the material, because every portion of the aerosol generating article is consumed in a similar manner.

In another aspect, the inductive coil further comprises one or more third areas, wherein the diameter of turns of the coil in the third area have a diameter smaller than the diameter of the turns in the first area and larger than the diameter of the turns in the second area, wherein the one or more third areas are arranged between the one or more first areas and the two or more second areas.

In a further aspect, the diameter of turns in the third area increases from a part closest to the second area, preferably in contact with the second area, to a part closest to the first area, preferably in contact with the first area. Preferably, the diameter of turns in the third area increases linearly from the part closest to the second area to the part closest to the first area.

In another aspect, in longitudinal direction of the inductive coil, the one or more third areas cover at least 2%, preferably at least 5%, more preferably at least 10%, even more preferably at least 20% and most preferably at least 30% of the length of the inductive coil.

In a further aspect, a first outer surface of the coil in the first area is parallel to a second outer surface of the coil in the second area, wherein a third outer surface of the coil in the third area is arranged at an angle between io° and 8o° relative to the first outer surface and the second outer surface. By including a third area with the above properties, the electromagnetic field can be provided in an even more homogeneous manner. This improves the effectiveness of the heating even further.

In a further aspect, the aerosol generating device further comprises a coil holder around which the turns of the coil are wound, the coil holder comprising recessed portions, each recessed portion receiving one turn of the inductive coil.

Having such a holder that receives the coil improves the durability and resilience of the inductive coil assembly against damage.

In another aspect, the coil holder has a substantially solenoid shape comprising an inner surface and an outer surface arranged in longitudinal direction of the coil holder, wherein the outer surface is configured to receive the inductive coil, and the inner surface delimits the receiving volume.

A coil holder formed in this manner provides optimal protection for the coil and operability for heating the tobacco product in the receiving volume.

In a further aspect, the coil holder comprises a high temperature polymer, wherein the coil holder is preferably manufactured using an additive manufacturing process, or an injection moulding process.

Providing the coil holder in this manner provides for a cheap manufacturing of the coil for receiving the coil. Additionally, the coil holder can be easily adapted to the variable shape of the coil and vice versa.

In another aspect, the receiving volume is designed to receive entirely a tobacco part of the aerosol generating article, advantageously with a longitudinal offset with respect with one of the ends of the inductive coil.

With the above, the amount of tobacco product in the receiving volume can be maximized. Furthermore, by arranging the tobacco part with a longitudinal offset with respect to one of the ends of the inductive coils, the tobacco part is arranged in the area with the most homogeneous electromagnetic field, such that heating of the tobacco is more constant. Thus, inhomogeneous electromagnetic field at the ends of the coil can be avoided.

In a further aspect, the induction coil comprises at least 5 turns, preferably at least 7 turns, more preferably at least 10 turns even mor preferably at least 12 turns and most preferably at least 16 turns, and/or at most 50 turns, preferably at most 30 turns, more preferably at most 25 turns, even more preferably at most 20 turns and most preferably at most 16 turns.

Another aspect of the invention is directed to an aerosol generating assembly comprising a susceptor, preferably included in the aerosol generating article, and an aerosol generating device as defined above.

In another aspect, the length of the susceptor in the longitudinal direction is smaller than the length of the inductive coil in the longitudinal direction.

With the above, positioning of the susceptor inside the receiving volume of the coil is facilitated, as the exact position of the susceptor inside the receiving volume is not as critical due to the homogenous electromagnetic field provided by the aerosol generating device as defined above. Preferred embodiments are now described, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure la: is a schematic view of the inductive coil;

Figure ib: is schematic side view of the outside surfaces of the coil in the first second and third areas, in an exemplary embodiment;

Figure 2: is schematic view of an aerosol generating article in an exemplary embodiment;

Figure 3a: shows the magnetic flux density inside the receiving volume of a conventional inductive coil;

Figure 3b: shows the magnetic flux density inside the receiving volume of an inductive coil according to the present invention;

Figure 4: shows a comparison of the B-field distribution obtained by the inductive coil according to the invention and by an inductive coil of the prior art;

Figure 5a: is a side view of the inductive coil arranged on a coil holder in an exemplary embodiment; Figure 5b: is a cross-sectional view of the inductive coil arranged on the coil holder in the exemplary embodiment;

Figure 5c: is a cross-sectional view of the inductive coil and the coil holder in the exemplary embodiment;

Figure 6: is a schematic view of an aerosol generating assembly according to an exemplary embodiment.

DETAILED DSCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described hereinafter with reference to the drawings.

In the following an aerosol generating device 100 for heating an aerosol generating article 200 will be described with more detail. The aerosol generating device 100 comprises an inductive coil 110 comprising a plurality of turns 120, forming a receiving volume 130 for receiving the aerosol generating article 200. The aerosol generating device too is configured to provide an electromagnetic field within the receiving volume 130 formed by the plurality of turns 120. The inductive coil 110 of the aerosol generating device too comprises one or more first areas 111 and two or more second areas 112. The one or more first areas 111 are arranged between at least two of the two or more second areas 112 in a longitudinal direction of the inductive coil 110. The diameter of the turns 120 of the coil 110 is larger in the one or more first areas 111 than in the two or more second areas 112. The one or more first areas 111 and the two or more second areas 112 are preferably arranged such that an outside surface of the inductive coil 110 has a trapezoidal shape (alternatively referred to as “plateau shape”).

In Fig. 2, an aerosol generating article according to an exemplary embodiment is illustrated. The aerosol generating article 200 may comprise an aerosol generating material 230 configured to generate an aerosol when heated. The aerosol generating material 230 may comprise a tobacco material. In addition or alternatively, the aerosol generating material 230 may comprise an aerosol generating substance other than tobacco, and/or a flavouring agent. In some examples, the aerosol generating material 230 may comprise material susceptible to an electromagnetic field. The material susceptible to an electromagnetic field may function as a susceptor 140 for the inductive coil 110 of the aerosol generating device 110. For example, when a changing electrical power is applied to the inductive coil 110, the inductive coil 110 provides a changing magnetic field in the receiving volume 130. When the aerosol generating article 200 is inserted into the receiving volume 130, in the susceptor 140, eddy currents are generated by the electromagnetic field. Due to the electrical resistance of the susceptor, the eddy currents heat up the susceptor through joule heating. The eddy currents/the joule heat maybe generated in a way such that the susceptor 140 heats up the aerosol generating material 230 until an aerosol is generated by the aerosol generating material 230. By controlling the electrical power supplied to the aerosol generating device 100 and thus the electromagnetic field induced inside the receiving volume 130, the aerosol generating article 200/the aerosol generating material 230 maybe heated in a desired/ constant manner. For controlling the provision of electrical power to the aerosol generating device too and thus for controlling the electromagnetic field inside the receiving volume 130, the aerosol generating device too may comprise or be connected to a control means for controlling the heating of the aerosol generating device too.

Preferably, the tobacco material, the aerosol generating substance other than tobacco, the flavouring agent and/or the material susceptible to an electromagnetic field/the susceptor are homogeneously distributed in the aerosol generating article 200. This means, that individual materials of the aerosol generating material 230 do not accumulate in individual areas of the aerosol generating article 200 but are mixed together during manufacturing of the aerosol generating material 230. By providing the material in the homogenously mixed manner, the heat distribution in the aerosol generating article 200 is constant/ evenly distributed when the article 200 is heated. This avoids an accumulation of extensive heat in some areas of the aerosol generating article 200 and temperatures that are too low to generate the aerosol from the aerosol generating material in some other areas.

The aerosol generating article 200 may comprise a plurality of parts with different properties. For example, the aerosol generating article 200 may comprise a tobacco part 210 comprising the tobacco material (or the other aerosol generating material) and/or a filter part 220 comprising a filter for filtering harmful material from the aerosol and/ or an additional susceptor part comprising an additional susceptor 140 (and/or additional material susceptible to an electromagnetic field) and/or an offset part configured to set the position of the tobacco material in the receiving volume 130 of the inductive coil 110. In Fig. la, an exemplary inductive coil no for generating the electromagnetic field for heating the aerosol generating article 200 is shown. The turns 120 of the inductive coil no form the receiving volume 130 for receiving the aerosol generating article 200, wherein the inductive coil 110 is configured to induce an electromagnetic field inside the receiving volume 130, when electrical power is applied to the coil 110. The inductive coil no shown in Fig. la comprises the first area 111 and the two second areas 112, wherein the first area 111 is arranged between the two second areas 112 in longitudinal direction of the inductive coil 110. While the exemplary inductive coil 110 of Fig. la may comprise any number of first 111 and second 112 areas, the exemplary inductive coil 110 shown in Fig. la comprises only one first area 111 and two second areas 112, wherein a first side of the first area (a left side of the first area 111 in Fig. la) may be located at a first side of one of the two second areas (the right side of the left second area 111 of the two second areas 112 in Fig. la) and a second side of the first area opposite to the first side (a right side of the first area 111 in Fig. la) maybe located on a first side of the second of the two second areas (the left side of the right second area 111 of the two second areas 112 in Fig. la). In longitudinal direction of the coil, the two second areas 112 are allocated at the two ends (at a proximal end and at a distal end) of the inductive coil 110, wherein the first area 111 is allocated in the centre portion of the inductive coil 110. However, in other examples, the inductive coil 110 may also comprise two or more first areas 111 and/or three or more second areas 112. The diameter of turns 120 of the coil in the one or more first areas 111 is larger than the diameter of turns 120 of the coil in the two or more second areas 112. This means that the coil extends further in the lateral/transversal direction in the first area 111 than in the two or more second areas 112. Preferably, the diameter of the turns 120 of the coil is substantially constant within the respective areas. That is, preferably, the diameter of turns 120 of the inductive coil 110 in the one or more first areas 111 is substantially constant and/ or the diameter of the turns 120 of the inductive coil 110 in the two or more second areas 112 is substantially constant. Preferably, the difference between the diameter of turns 120 of the coil in the one or more first areas 111 is at least 3% larger, more preferably at least 5% larger, even more preferably at least 7% larger, even more preferably at least 10 % larger, more preferably at least 12 % larger and most preferably at least 15% larger than the diameter of turns 120 of the coil in the two or more second areas 112. In one particular example, the diameter of turns 120 in the first area 111 is between 4.00 mm to 4.20 mm and the diameter of turns 120 in the two or more second areas 112 is between 3.6 mm and 3.8 mm, preferably the diameter of turns 120 in the first area 111 is between 4.05 mm to 4.15 mm and the diameter of turns 120 in the two or more IO second areas 112 is between 3.65 mm and 3.75 mm and more preferably the diameter of turns 120 in the first area 111 is between 4.1 mm and 4.13 mm and the diameter of turns 120 in the two or more second areas 112 is between 3.68 mm and 3.72 mm, most preferably the diameter of tuns in the first area 111 is 4.12 mm and the diameter of turns 120 in the two or more second areas 112 is 3.7 mm. Preferably, the diameter of the turns of the coil in the respective areas, e.g., in the one or more first areas 111 and/or the two or more second areas 112, has at most 15% variance in diameter, more preferably at most 10% variance in diameter, even more preferably at most 5% variance in diameter and most preferably substantially no variance in diameter.

In the longitudinal direction of the inductive coil 110, the one or more first areas 111 cover at least 50%, preferably at least 60%, more preferably at least 70%, even more preferably at least 80% and most preferably at least 90% of the length of the inductive coil 110. Moreover, the two or more second areas 112 preferably cover at least 5%, preferably at least 10%, more preferably at least 15%, even more preferably at least 20% and most preferably at least 30% of the length of the inductive coil 110 in the longitudinal direction. In one particular example, in longitudinal direction, the first area 111 covers between 45% and 95% of the length of the inductive coil 110, preferably the first area 111 covers between 47% and 93% of the length of the inductive coil 110, and more preferably the first area 111 covers between 50% and 90% of the length of the inductive coil 110. Additionally, or alternatively, each of the two or more second areas 112 cover between 3% and 35% of the length of the inductive coil 110, preferably between 4% and 32% of the length of the inductive coil 110 and most preferably between 5% and 30% of the length of the inductive coil 110.

In one embodiment, the inductive coil 110 is a single layer coil. This means that individual turns 120 of the inductive coil 110 area not stacked on top of each other but allocated adjacent to each other. Alternatively, the inductive coil 110 may be a multilayer coil, where individual turns 120 of the inductive coil 110 are stacked on top of each other. In the embodiments shown in the figures, a single layer coil is used.

The diameter/or cross-section of the wire used for the inductive coil 110, i.e., the diameter/ cross-section of each of the individual turns 120 is preferably substantially constant, wherein preferably a litz wire is used for the inductive coil 110. Preferably, the wire forming the induction coil has a cross-sectional area with at most 15% variance in diameter, preferably at most 10% variance in diameter, more preferably at most 5% variance in diameter and most preferably substantially no variance in diameter in at least 70 %, preferably at least 8o% more preferably at least 90% and most preferably in at least 95% of the length of the wire in the one or more first areas and/ or in the two or more second areas.

Preferably, the induction coil comprises at least 5 turns 120, preferably at least 7 turns 120, more preferably at least 10 turns 120 even mor preferably at least 12 turns 120 and most preferably at least 16 turns 120, and/or at most 50 turns 120, preferably at most 30 turns 120, more preferably at most 25 turns 120, even more preferably at most 20 turns 120 and most preferably at most 16 turns 120.

In Fig. lb, a schematic view of another exemplary inductive coil 110 is shown, wherein the diameter of turns 120 at respective longitudinal positions of the inductive coil 110 is shown. In addition to the properties described with reference to Fig.i, the inductive coil 110 may further comprise one or more third areas 113 between the two or more second areas 112 and the one or more first areas 111. An outside surface of the one or more third areas 113 forms an angle with the outside surface of an adjacent first area 111 and/or an adjacent second area 112. In the particular example in Fig. ib, the inductive coil 110 comprises two third areas 113. The diameter of turns 120 of the coil in the one or more third areas 113 is smaller than the diameter of the turns 120 in the first area 111 and larger than the diameter of the turns 120 in the second area. Preferably, as shown in Fig. ib, the diameter of turns 120 in the third area at a position adjacent (or close to) to one of the two or more second areas 112 is smaller than the diameter of turns 120 in the third area at a position adjacent (or close) to the one or more first position.

Preferably, the diameter of turns 120 of the inductive coil 110 in the third area increases from a diameter substantially similar to the diameter of the turns 120 of the inductive coil 110 in the two or more second areas 112 to a diameter substantially similar to the diameter of the turns 120 of the inductive coil 110 in the one or more first areas 111. Furthermore, in longitudinal direction of the inductive coil 110, the one or more third areas 113 may cover at least 2%, preferably at least 5%, more preferably at least 10%, even more preferably at least 20% and most preferably at least 30% of the length of the inductive coil 110. Preferably, the wire forming the induction coil has a cross-sectional area with at most 15% variance in diameter, preferably at most 10% variance in diameter, more preferably at most 5% variance in diameter and most preferably substantially no variance in diameter in at least 70 %, preferably at least 80% more preferably at least 90% and most preferably in at least 95% of the length of the wire in the one or more third areas 113. In Figs. 3a and 3b, magnetic flux density simulations of a conventional inductive coil 110a (as known in the art), i.e., an inductive coil 110 having a constant coil diameter (Fig. 3a) and of an inductive coil 110 as described above (Fig. 3b). Both coils used for the simulation have a length of around 25 mm in the longitudinal direction. In both simulations, a similar constant electrical power was applied to the inductive coils 110. The resulting magnetic flux density norms are plotted with respect to the corresponding spatial positions (coordinates in a 2D space), wherein the magnetic flux density values are normalized to a maximum value of 10. Normalizing the magnetic flux density values facilitates comparing the simulation results shown in Fig. 3a with the results shown in Fig. 3b. Hence, a magnetic flux density value of 5 in Fig. 3a is the same as a magnetic flux value of 5 in Fig. 3b, and a magnetic flux value of 7 in Fig. 3a corresponds to a magnetic flux value of 7 in Fig. 3b.

The inductive coil 110 used for the magnetic flux density simulation of Fig. 3a has a constant diameter of around 5 mm. As can be seen in Fig. 3a, in the centre of the volume of the inductive coil 110, an area with high magnetic flux density 320 with a value 7 (a little above 7) is formed. From the highest magnetic flux in the centre of the inside volume of the inductive coil 110, the magnetic flux density decreases to a value of around 4 to 5 at the ends of the inductive coil 110. That is, the highest magnetic flux density of 7 is achieved in the area of - 9 mm to + 9 mm on the y-Axis of the plot in Fig. 3a, wherein the magnetic flux density is larger at a position close to the wire of the turns 120 of the inductive coil 110 and decreases towards the centre of the receiving volume inside the inductive coil 110. An area with low magnetic flux density 310 thus extends from 7 to 12.5 (- 7 to - 12.5, respectively) in the centre of the receiving volume.

In comparison, the inductive coil 110 used for the simulation of the magnetic flux density in Fig. 3b corresponds to the inductive coil 110 according to the above examples. In this particular example, the inductive coil 110 comprises of two second areas 112 with a diameter of around 5 mm (similar to the diameter of the inductive coil 110 of Fig. 3b) and a first section with a diameter of around 7 mm. The two second areas 112 of the inductive coil 110 are positioned at the two ends of the coil. The two second areas 112 each extend around 3.3 mm in the longitudinal direction, and the first area 111 extends around 16 mm. The inductive coil 110 used for this simulation also comprises two third areas 113 connecting the first area 111 with the two second areas 112, wherein the two third areas 113 each extend around 1.2 mm in the longitudinal direction. As can be seen in Fig. 3b, the inductive coil according to the present invention also forms a large area with high magnetic flux density 320 inside the receiving volume of the inductive coil no. In the area with high magnetic flux density, the magnetic flux density also reaches a maximum of around 7 (a little below 7). In this example, the area with high magnetic flux density extends in the area of - 12 mm to + 12 mm in the y-Axis of the plot shown in Fig. 3b. Contrary to the conventional inductive coil 110a, in the receiving volume 130 of the inductive coil no according to the present invention, the magnetic flux density does decreases towards the centre of the receiving volume of the inductive coil 110, according to the above examples. Only at the edges of the inductive coil 110, the magnetic flux density decreases to a value of around 4 to 5. Accordingly, the area with low magnetic flux density 310 is relatively small, wherein the area with low magnetic flux density 310 extends from 9.5 to 12.5 (- 9.5 to - 12.5, respectively) in the centre of the receiving volume.

With a coil according to the above examples, an improved uniformity of (77 =

1 — is reached in the volume of interest, wherein over 80% of the length of

the coil in longitudinal direction, and over 70% of the radius (with respect to the radius of the second rea) has a uniformity of above 80%, and even 90%. By having such a homogeneous B-field within the volume of interest, the susceptor 140 inside the aerosol generating article 200 can be heated more evenly. This allows to heat the aerosol generating more evenly and more precisely without requiring extensive calibration processes to find proper heating parameters.

By comparing the results obtained by the simulations of Figs. 3a and 3b, it can be seen that the spatial magnetic flux density distribution, i.e., the magnetic field is more homogenous within the receiving volume of the inductive coil 110 shown in Fig. 3b when compared the inductive coil 110 having a constant diameter, as shown in Fig. 3a. That is, while the absolute values of the magnetic flux density in areas with high magnetic flux density 320 and in areas with low magnetic flux density 310 are similar, the size of the areas with high magnetic flux density 320 and areas with low magnetic flux density 310 vary greatly. In particular, close to the centre of the respective inductive coils 110 the area with low magnetic flux density 310 is substantially larger in the inductive coil 110 having a constant diameter, when compared to the inductive coil 110 according to the present invention.

To highlight the differences between the magnetic flux density distribution between the inductive coil 110 according to the present invention and the conventional inductive coil 110a even further, the respective normalized magnetic fields were plotted with respect to the longitudinal position as shown in Fig. 4. To facilitate the comparison, the features of the exemplary coil arrangement of Figs, la and ib are provided at the corresponding position in the plot.

As can be seen in the plot of Fig. 4, the magnetic flux distribution 420, i.e., the strength of the magnetic field, for the conventional inductive coil 110a has a substantially semiellipse shape. That is, the magnetic flux density is the highest in the very centre of the inductive coil 110 and decreases gradually from the centre of the coil, wherein the amount of decrease of magnetic flux density increases with the distance to the centre of the coil (in the longitudinal direction). Contrary, the magnetic flux distribution 410 of the magnetic field generated inside the receiving volume of the inductive coil 110 according to the present invention, is much more constant. In particular, while the decrease of the magnetic flux density in the area of the two second areas 112 is similar to the decrease of the magnetic flux density at a similar position in the convention inductive coil 110a, the magnetic flux density is substantially constant in the first area. Accordingly, the magnetic flux density distribution of the inductive coil 110 according to the present invention is substantially trapezoidal.

When inserting an aerosol generating article 200 with the susceptor 140 inside the receiving volume of the respective inductive coils 110, the aerosol generating article 200 inserted in the convention inductive coil 110a will naturally heat more in the area with high magnetic flux density 320 (i.e., in the centre of the receiving volume) and less in the areas of the receiving volume that are arranged at a distance to the centre. Hence, the aerosol generating article 200 will not be heated homogenously. This can lead to overheating (which leads to a burnt feel for the user) of the material in the centre and underheating of the material (which may then not generate aerosol) in a distance to the centre. Consequently, the smoking experience can be dissatisfactory for the user, and/or smoking material is wasted. Moreover, controlling the temperature supplied to the aerosol generating material in the aerosol generating article 200 can be difficult, as changing the electrical power supplied to the inductive coil 110 does not lead to similar changes to every area of the aerosol generating article 200 in a similar manner.

In contrast, when inserting the aerosol generating article 200 into the receiving volume of the inductive coil 110 according to the present invention, the magnetic field density over the whole aerosol generating article 200 is substantially constant. Accordingly, by changing the power supplied to the inductive coil 110, the same change to the magnetic field applies to every area of the aerosol generating article 200 in a similar manner. This facilitates control of the temperature of the aerosol generating material in a way that all of the aerosol generating material in the aerosol generating article 200 is heated equally. For example, a temperature control means in the aerosol generating device 100 may set the power supplied to the heating element comprising the inductive coil 110 according to the present invention, such that the temperature in the aerosol generating device 100 reaches the point at which the aerosol generating material, such as the tobacco material, generates an inhalable aerosol for the user. Due to the constant heating of the aerosol article, in some embodiments, no further sensors or control means are necessary to provide a satisfactory user experience with optimized material consumption.

Furthermore, as can be seen in Fig. 4, the magnetic flux density (i.e. , the strength of the magnetic field) generated by the inductive coil 110 according to the present invention is particularly homogenous in the receiving volume of the inductive coil 110 corresponding to the first area. At the edges of the inductive coil 110, the magnetic flux density decreases similar to the convention inductive coil 110a. Accordingly, preferably, the aerosol generating article 200 is inserted into the receiving volume in a manner, such that the material susceptible to the electromagnetic field and/or the aerosol generating material is allocated only inside the receiving volume corresponding to the first area. For example, the aerosol generating article 200 may be inserted into the receiving volume 130 with an offset in the longitudinal direction, such that the aerosol generating article 200 does not enter the receiving volume 130 corresponding to one of the two or more second areas 112. Alternatively, the aerosol generating article 200 may be constructed in such a manner that aeras of the aerosol generating article 200 corresponding to the two or more second areas 112 do not comprise material susceptible to the electromagnetic field and/or aerosol generating material, such as tobacco. Additionally, or alternatively, the aerosol generating device too may be configured, such that the aerosol generating article 200 cannot be inserted into one of the two or more second areas 112. For example, the receiving volume 130 for receiving the aerosol generating article 200 may be shaped such that it extends only in an area corresponding to one of the two or more second areas 112 and one the first area 111.

To facilitate providing the inductive coil 110 according to the above examples, the aerosol generating device too may comprise a coil holder 500 around which the turns 120 of the coil are wound. One exemplaiy coil holder 500 is shown in Figs. 5a, 5b and 5c. Fig. 5a shows the coil holder 500 with the inductive coil 110 being wound around the coil holder 500. Fig. 5b shows the coil holder 500 with the inductive coil 110 wound around the coil holder 500, wherein an outer surface of the coil holder 500 receiving the inductive coil no is shown. Fig. 5c shows a cross sectional view of the coil holder 500 and the inductive coil no showing the receiving volume inside the coil holder 500/the inductive coil 110. The coil holder 500 maybe fixed to a device body or an internal chassis extending through the device body.

The coil holder 500 may comprise recessed portions 510, wherein preferably each recessed portion 510 is configured to receive one turn of the inductive coil 110. The coil holder 500 preferably has a substantially solenoid shape comprising an inner surface 511 and the outer surface 512 arranged in longitudinal direction of the coil holder 500, wherein the outer surface 512 is configured to receive the inductive coil 110, and the inner surface 511 delimits the receiving volume. The inside surface of the coil holder 500 preferably forms a tube-like shape that delimits the receiving volume for receiving the aerosol generating article 200. Preferably, the coil holder 500 forms the receiving volume in a manner such that tube-shaped aerosol generating articles 200, such as aerosol generating articles 200 having a cigarette shape, fully fill the cavity when inserted. Preferably, the receiving volume 130 formed by the inner surface 511 of the coil holder 500 is configured to receive entirely the tobacco part of the aerosol generating article 200.

The recessed portions 510 may also be a single recessed portion 510 that is wound in a corkscrew manner around the outer surface 512 of the coil holder 500 such that it appears that the coil holder 500 comprises more than one recessed portion. Accordingly, in the following, multiple recessed portions 510 also include the configuration of a single recessed portion 510 that appears to have multiple recessed portions 510 due to being configured in the corkscrew manner.

The coil holder 500 comprises one or more first areas 521 and two or more second areas 522, wherein the one or more first areas 521 are arranged between at least two of the two or more second areas 522 in a longitudinal direction of the coil holder 500. The diameter of the coil holder 500 is larger in the one or more first areas 521 than in the two or more second areas 522.

This means that in the first area 521 the coil holder 500 extends further in the lateral/transversal direction than in the two or more second areas 522. Preferably, the diameter of the coil holder 500 is substantially constant within the respective areas. Preferably, the diameter of the coil holder 500 in the respective areas has at most 15% variance in diameter, more preferably at most 10% variance in diameter, more even more preferably at most 5% variance in diameter and most preferably substantially no variance in diameter. Therefore, preferably, the diameter of the coil holder 500 in the one or more first areas 521 is substantially constant and/or the diameter of the coil holder 500 in the two or more second areas 522 is substantially constant. Therefore, the diameter of the coil holder 500 preferably has at most 15% variance in diameter, more preferably at most 10% variance in diameter, more even more preferably at most 5% variance in diameter and most preferably substantially no variance in diameter in the one or more first areas 521 and/or the two or more second areas 522. In other words, the coil holder 500 defines a complementaiy shape to the shape of the coil. Preferably, the difference between the diameter of the coil holder 500 in the one or more first areas 521 is at least 3% larger, more preferably at least 5% larger, even more preferably at least 7% larger, even more preferably at least 10 % larger, more preferably at least 12 % larger and most preferably at least 15% larger than the diameter of the coil holder 500 in the two or more second areas 522. In one particular example, the diameter of the first area 521 of the coil holder 500 is between 4.00 mm to 4.20 mm and the diameter of the coil holder 500 in the two or more second areas 522 is between 3.6 mm and 3.8 mm, preferably the diameter of the coil holder 500 in the first area 521 is between 4.05 mm to 4.15 mm and the diameter of the coil holder 500 in the two or more second areas 522 is between 3.65 mm and 3.75 mm and more preferably the diameter of the coil holder 500 in the first area 521 is between 4.1 mm and 4.13 mm and the diameter of the coil holder 500 in the two or more second areas 522 is between 3.68 mm and 3.72 mm, most preferably the diameter of the coil holder 500 in the first area 521 is 4.12 mm and the diameter of the coil holder 500 in the two or more second areas 522 is 3.7 mm.

In the longitudinal direction of the coil holder 500, the one or more first areas 521 cover at least 50%, preferably at least 60%, more preferably at least 70%, even more preferably at least 80% and most preferably at least 90% of the area which receives the wire of the inductive coil 110. Moreover, the two or more second areas 522 preferably cover at least 5%, preferably at least 10%, more preferably at least 15%, even more preferably at least 20% and most preferably at least 30% of the length of the area receiving the wire of the inductive coil 110 in the longitudinal direction. In one particular example, in longitudinal direction, the first area 521 covers between 45% and 95% of the length of the area receiving the wire of the inductive coil 110, preferably the first area 521 covers between 47% and 93% of the length of the area receiving the wire of the inductive coil 110, and more preferably the first area 521 covers between 50% and 90% of the length of the area of receiving the wire of the inductive coil 110. Additionally, or alternatively, each of the two or more second areas 522 cover between 3% and 35% of the length of the area receiving the wire of the inductive coil 110, preferably between 4% and 32% of the length of the area receiving the wire of the inductive coil 110 and most preferably between 5% and 30% of the length of the area receiving the wire of the inductive coil 110.

Preferably, the coil holder 500 further comprises one or more third areas 523, wherein the diameter of the coil holder 500 in the third area 523 is smaller than the diameter of the coil holder 500 in the first area 521 and larger than the diameter of the turns in the second area 522, wherein the one or more third areas 523 are arranged between the one or more first areas 521 and the two or more second areas 522.

Preferably, each of the recessed portions 510 configured to receive the wire of the inductive coil 110 has a similar cross-sectional area than the wire used for the inductive coil 110, i.e., the cross-sectional area of each of the individual turns 120 of the inductive coil 110. Preferably the cross-sectional area of the of the recessed portions 510 configured to receive the wire is substantially constant, wherein preferably a litz wire is used for the inductive coil 110. Preferably, the cross-sectional area of the recessed portions 510 configured to receive the wire has a cross-sectional area with at most 15% variance in diameter, preferably at most 10% variance in diameter, more preferably at most 5% variance in diameter and most preferably substantially no variance in diameter in at least 70 %, preferably at least 80% more preferably at least 90% and most preferably in at least 95% of the length of the recessed portions 510 in the one or more first areas 521 and/or in the two or more second areas 522.

Preferably, the recessed portion(s) 510 of the coil holder 500 is/are configured to create an inductive coil 110 having at least 5 turns 120, preferably at least 7 turns 120, more preferably at least 10 turns 120 even mor preferably at least 12 turns 120 and most preferably at least 16 turns 120, and/or at most 50 turns 120, preferably at most 30 turns 120, more preferably at most 25 turns 120, even more preferably at most 20 turns 120 and most preferably at most 16 turns 120, when the wire of the inductive coil 110 is inserted into the recessed portion.

By using the coil holder 500, the manufacturing of the inductive coil 110 according to the present invention is facilitated. For example, the inductive coil maybe manufactured by winding the wire of the inductive coil around the coil holder 500, such that the wire is placed inside the recessed portion 510 during the manufacturing process. This increases stability of the inductive coil 110 during the manufacturing process and makes sure that the individual turns 120 of the inductive coil 110 have the desired position/diameter. Furthermore, the durability/ stability of the inductive coil no according to the present invention increases when positioned in the coil holder 500. Additionally, the coil holder 500 allows to construct the inductive coil 110 from a large variety of wires, as even flexible wires are kept in position. For example, if it is preferably to use a litz wire, which may be flexible, for the inductive coil 110, the coil holder 500 is configured to a) move the litz wire into the desired position and b) keep the litz wire in the desired position, even when external forces are applied to the aerosol generating device 100. Thereby increasing the durability of the inductive coil 110 and of the heating arrangement.

To avoid damage to the coil holder 500, and to ensure that the wire of the inductive coil 110 is directed into the correct position, even at high temperatures, the coil holder 500 preferably comprises a high temperature. Preferably, the coil holder 500 is manufactured using an additive manufacturing process, such as material extrusion, binder jetting, directed energy deposition, material jetting, powder bed fusion, sheet lamination, or vat polymerization, or an injection moulding process.

Accordingly, the above coil holder 500, is configured to direct the wire into a position that provides a more homogeneous electromagnetic field to a susceptor in the receiving volume of the inductive coil 110/the coil holder 500, such that the aerosol generating article 200 inserted into the receiving volume is heated uniformly.

The invention also relates to an aerosol generating assembly 600 comprising the abovedescribed aerosol generating device 100 and a susceptor 140, preferably included in the aerosol generating article 200. Fig. 6 shows an aerosol generating assembly 600, according to an exemplary embodiment. The aerosol generating assembly 600 may further comprise a batteiy 620 for providing electrical power to the components of the aerosol generating assembly 600. Additionally or alternatively, the aerosol generating assembly 600 may comprise a control means 610. The control means 610 being configured to control the electrical power provided to the aerosol generating device 110 such that the heating and provision of aerosol to a user are controlled. LIST OF REFERENCE SIGNS USED

100 aerosol generating device;

110 inductive coil; noa convention inductive coil; in first area;

112 second area;

H3 third area;

120 turns;

130 receiving volume;

140 susceptor;

200 aerosol generating article;

210 tobacco part;

220 filter part;

230 aerosol generating material;

310 area with low magnetic flux density;

320 area with high magnetic flux density;

410 normalized magnetic field distribution of the inductive coil;

420 normalized magnetic field distribution of a conventional inductive coil;

500 coil holder;

510 recessed portions;

511 inner surface of the coil holder;

512 outer surface of the coil holder;

521 first area of the coil holder;

522 second area of the coil holder;

523 third area of the coil holder;

600 aerosol generating assembly;

610 control means;

620 battery.

Claims

July 19, 2024

JT International SA J169566WO CKA/Lef/dzd

1. An aerosol generating device (100) for heating an aerosol generating article (200), comprising: an inductive coil (110) comprising a plurality of turns (120) and configured to provide an electromagnetic field within a receiving volume (130) configured to receive the aerosol generating article (200), the inductive coil (110) comprising: one or more first areas (111) and two or more second areas (112), wherein the one or more first areas (111) are arranged between at least two of the two or more second areas (112) in a longitudinal direction of the inductive coil (110), wherein the diameter of the turns (120) of the coil (110) is larger in the one or more first areas (111) than in the two or more second areas (112).

2. The aerosol generating device (100) according to the preceding claim, wherein the diameter of the turns (120) of the coil in the one or more first areas (111) is substantially constant and/or the diameter of the turns (120) of the coil in the two or more second areas (112) is substantially constant.

3. The aerosol generating device (too) according to any one of the preceding claims, wherein the diameter of the turns (120) of the coil in the one or more first areas

(111) is at least 3% larger, preferably at least 5% larger, more preferably at least 7% larger and most preferably at least 10 % larger than the diameter of turns of the coil in the two or more second areas (112).

4. The aerosol generating device (100) according to any one of the preceding claims, wherein in longitudinal direction of the inductive coil (110), the one or more first areas (111) cover at least 50%, preferably at least 60%, more preferably at least 70%, even more preferably at least 80% and most preferably at least 90% of the length of the inductive coil, and/or in longitudinal direction of the inductive coil (110), the two or more second areas

(112) cover at least 5%, preferably at least 10%, more preferably at least 15%, even more preferably at least 20% and most preferably at least 30% of the length of the inductive coil.

5. The aerosol generating device (100) according to any one of the preceding claims, wherein the two second areas (112) are arranged at a distal end of the inductive coil (110) and at a proximal end of the inductive coil (110).

6. The aerosol generating device (100) according to the preceding claim, wherein the inductive coil (110) comprises only one first area (111) and two second areas (112).

7. The aerosol generating device according to any one of the preceding claims, wherein the inductive coil (110) is a single layer coil and/or the inductive coil (110) is formed by a single wire and/or the diameter of the wire of the inductive coil (110) has at most 15% variance in diameter, preferably at most 10% variance in diameter, more preferably at most 5% variance in diameter and most preferably substantially no variance in at least 70 %, preferably at least 80% more preferably at least 90% and most preferably in at least 95% of the length of the wire in the one or more first areas and/ or in the two or more second areas.

8. The aerosol generating device (too) according to any one of the preceding claims, wherein the inductive coil (110) further comprises one or more third areas (113), wherein the diameter of turns of the coil in the third area (113) is smaller than the diameter of the turns in the first area (111) and larger than the diameter of the turns in the second area (112), wherein the one or more third areas (113) are arranged between the one or more first areas (111) and the two or more second areas (112).

9. The aerosol generating device (too) according to the preceding claim, wherein in longitudinal direction of the inductive coil (110), the one or more third areas (113) cover at least 2%, preferably at least 5%, more preferably at least 10%, even more preferably at least 20% and most preferably at least 30% of the length of the inductive coil (110).

10. The aerosol generating device (too) according to any one of the preceding claims, further comprising a coil holder (500) around which the turns of the coil are wound, the coil holder (500) comprising recessed portions (510), each recessed portion (510) receiving one turn (120) of the inductive coil.

11. The aerosol generating device (100) according to the preceding claim, wherein the coil holder (500) has a substantially solenoid shape comprising an inner surface (511) and an outer surface (512) arranged in longitudinal direction of the coil holder (500), wherein the outer surface (512) is configured to receive the inductive coil (110), and the inner surface (511) delimits the receiving volume (130).

12. The aerosol generating device (100) according to claims 10 or 11, wherein the coil holder (500) comprises a high temperature polymer, wherein the coil holder (500) is preferably manufactured using an additive manufacturing process or an injection moulding process.

13. The aerosol generating device (100) according to any one of the preceding claims, wherein the receiving volume (130) is configured to receive a tobacco part (210) of the aerosol generating article (200).

14. The aerosol generating device (too) according to claim 13, wherein the receiving volume (130) is configured to receive the tobacco part (210) of the aerosol generating article (200) with a longitudinal offset (520) with respect to one the ends of the inductive coil (110).

15. The aerosol generating device (too) according to any one of the preceding claims, wherein the receiving volume (130) is configured to receive entirely a tobacco part (210) of the aerosol generating article (200).

16. The aerosol generating device (too) according to claim 15, wherein the receiving volume (130) is configured to receive entirely the tobacco part (210) of the aerosol generating article (200) with a longitudinal offset (520) with respect to one the ends of the inductive coil (110).

17. The aerosol generating device (too) according to any one of the preceding claims, wherein the inductive coil (110) comprises at least 5 turns (120), preferably at least 7 turns (120), more preferably at least 10 turns (120) even mor preferably at least 12 turns (120) and most preferably at least 16 turns (120), and/or at most 50 turns (120), preferably at most 30 turns (120), more preferably at most 25 turns (120), even more preferably at most 20 turns (120) and most preferably at most 16 turns (120). 18. An aerosol generating assembly (600) comprising: a susceptor (140), preferably included in the aerosol generating article (200); and an aerosol generating device (100) according to any one of the preceding claims.