Aerosol generating article

Abstract

An aerosol-generating article (101) is described. The aerosol-generating article (101) comprises: a housing (103) extending along a first axis; a material portion (113) disposed within the housing, wherein the material portion includes a substrate (105) for generating an aerosol and one or more inductively heatable susceptors (107) for heating the substrate (105); and a conductive ring (111) spaced apart from the material portion (113) along the first axis and configured to generate a reverse magnetic field aligned relative to the oscillating magnetic field when there is an oscillating magnetic field substantially aligned along the first axis.

Description

Field of the Invention

[0001] The present invention relates to an aerosol generating article for generating an aerosol for inhalation by a user, and to an aerosol generating system incorporating said article. Background Art

[0002] As an alternative to traditional combustible tobacco products, aerosol generating devices have gained popularity. Heated tobacco products, also known as heat-not-burn products, are a type of aerosol generating device configured to heat a tobacco substrate to a temperature sufficient to generate an aerosol from the substrate but not so high as to cause the tobacco to burn. Although the present specification particularly refers to heated tobacco products, it will be understood that the following discussion is equally applicable to aerosol generating systems incorporating other types of heatable substrates.

[0003] In some heated tobacco products, the tobacco substrate is heated by one or more inductively heatable susceptors located within the article. When the article is placed within an oscillating magnetic field, the susceptor couples to the magnetic field and generates heat, which in turn heats the substrate. The rate of heating the substrate depends on the magnetic field strength at the location of the susceptor, but safety concerns regarding the strength of the electromagnetic field to which the user is exposed limit the magnetic field strength that can be generated by such a device, and thus limit the heating rate that can be achieved.

[0004] Accordingly, there is a need for a method of rapidly heating an aerosol generating substrate while avoiding exposing the user to excessive electromagnetic fields. Summary of the Invention

[0005] A first aspect of the present invention provides an aerosol generating article comprising: a housing extending along a first axis; a material portion disposed within the housing, wherein the material portion includes a substrate for generating an aerosol and one or more inductively heatable susceptors for heating the substrate; and a conductive ring spaced apart from the material portion along the first axis and configured to generate a reverse magnetic field that is aligned relative to an oscillating magnetic field when there is an oscillating magnetic field that is substantially aligned along the first axis.

[0006] The opposing magnetic field generated by the conductive ring has the effect of reducing the net magnetic field strength outside the region surrounding the article. Thus, when the article is inductively heated by an oscillating magnetic field (e.g., supplied by a coil within which the article is placed), the strength of the electromagnetic field to which the user is exposed is reduced compared to the strength experienced when no conductive ring is present. A further advantage provided by the present invention is that the present invention eliminates the need for electromagnetic shielding in the device providing the oscillating magnetic field, thereby allowing for a simplified construction of the device.

[0007] The conductive ring may be formed of any suitable conductive material, such as copper, silver, or aluminum. The conductive ring may be any conductive structure that permits current to circulate about a first axis so as to establish an opposing magnetic field.

[0008] In some preferred embodiments, the conductive ring is shaped as a ring lying in a plane substantially perpendicular to the first axis, or as a hollow cylinder whose cylindrical axis is substantially aligned with the first axis. Thus, the orifice of the ring or cylinder will be aligned along the same direction as the air flow channel, thereby minimizing the obstruction of the conductive ring to the channel. The ring or cylinder may have a solid surface or, alternatively, may be formed of a grid or mesh of conductive material.

[0009] Preferably, the conductive ring comprises a metal, most preferably copper or silver. However, the conductive ring may incorporate other conductive materials, such as, for example, graphite or conductive polymers. Metals (in particular, copper and silver) typically have relatively high electrical conductivity and thus are able to effectively generate a relatively strong opposing magnetic field when placed in an initial oscillating magnetic field. Additionally, highly conductive materials (such as metals) are advantageous because they prevent the current induced in the conductive ring from generating excessive heat through resistive heating.

[0010] In some preferred embodiments, the conductive ring is integral with the housing. For example, the conductive ring may be a layer of conductive material within the housing or may be applied to the exterior of the housing. In other preferred embodiments, the conductive ring is carried by an adapter paper disposed on the outer surface of the housing. In the latter case, the conductive ring may be integral with the adapter paper (such as a layer within the adapter paper or applied to the exterior of the adapter paper).

[0011] The aerosol-generating article preferably includes a filter for filtering the aerosol generated by the substrate. For example, the filter may be disposed inside the air flow channel. The filter may also be configured to filter any potentially harmful substances in the aerosol and may cool the aerosol passing through the filter. In a particularly preferred embodiment, the conductive ring is disposed between the material portion and the filter.

[0012] In a preferred embodiment, one or more inductively heatable susceptors comprise a first material and the conductive ring comprises a second material having a lower resistivity than the first material. Advantageously, the conductive ring has a relatively high electrical conductivity, thus ensuring that the opposing magnetic field is relatively strong and minimizing heating of the ring due to the induced current. Conversely, it is advantageous for the material of the inductively heatable susceptor to have a relatively low electrical conductivity, such that the susceptor is rapidly heated due to the presence of the oscillating magnetic field. For example, the first material may be aluminum and the second material may be copper. However, in other embodiments, the first material and the second material may be the same. For example, both may be aluminum.

[0013] A second aspect of the present invention provides an aerosol generating system, the aerosol generating system comprising: an aerosol generating article according to the first aspect of the present invention; and a heating device, the heating device comprising an inductor for generating an oscillating magnetic field substantially aligned along the first axis for heating the one or more inductively heatable susceptors. The heating device may be a hand-held device that promotes the consumption of the generated vapor by inhalation and may include features such as a power source for powering the inductor and a mouthpiece in fluid communication with the chamber whereby a user can draw aerosol from the article. As explained above, the presence of the conductive ring in the aerosol generating article allows for a simplified construction of the heating device since the heating device does not need to provide electromagnetic shielding to protect the user from high electromagnetic fields.

[0014] In a preferred embodiment, the heating device comprises a chamber adapted to receive the aerosol generating article and to hold the aerosol generating article in the oscillating magnetic field.

[0015] Advantageously, the inductor comprises an electrical coil, for example, a helical coil. When an electric current passes through the coil, the magnetic field generated inside such a coil will be strong and highly uniform because the magnetic field lines are parallel to each other along the axis around which the coil is wound. Thus, the coil can be adapted such that the aerosol generating article can be disposed inside the coil, preferably such that the air flow channel is concentric with the coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Examples of aerosol generating articles and aerosol generating systems will now be described with reference to the accompanying drawings, in which:

[0017] Figure 1 is a cross-sectional view of a first embodiment of an aerosol generating article according to the first aspect of the present invention;

[0018] Figure 2 shows an exemplary conductive ring suitable for incorporation in Figure 1 the aerosol generating article;

[0019] Figure 3 is a cross-sectional view of a second embodiment of an aerosol generating article according to the first aspect of the present invention;

[0020] Figure 4 is a cross-sectional view of a third embodiment of an aerosol generating article according to the first aspect of the present invention;

[0021] Figure 5 is a cross-sectional view of a fourth embodiment of an aerosol generating article according to the first aspect of the present invention; and

[0022] Figure 6 is a cross-sectional view of an aerosol generating system according to the second aspect of the present invention. Detailed implementation mode

[0023] Figure 1 It is a cross-sectional view of the aerosol-generating article 101 according to the first aspect of the present invention. The article 101 is surrounded by a cylindrical housing 103 that defines an air flow channel 115. The air flow channel 115 extends along a first axis that is oriented in the direction marked A in this figure.

[0024] One end of the air flow channel 115 within the housing 103 is a material portion 113. The material portion 113 includes a substrate 105 that includes a material (such as reconstituted tobacco) that generates an aerosol for consumption by inhalation when heated. The material portion 113 also includes a plurality of inductively heatable sensors 107 embedded in the substrate 105. The sensors 107 can be made of, for example, aluminum. Other suitable materials include iron, nickel, stainless steel, or alloys (e.g., nichrome or nickel-copper). In this example, each sensor 107 is in the form of an elongated strip or rod that is arranged to extend along the air flow channel 115 in the direction of the first axis A.

[0025] The other end of the air flow channel 115 is a filter 109. When the aerosol generated by the substrate 105 is drawn through the air flow channel 115 in the direction of the first axis A, the aerosol passes through the filter 109, which cools the aerosol. The filter 109 can also be configured to filter any adverse or potentially harmful substances from the aerosol.

[0026] A conductive ring in the form of a hollow cylinder 111 is disposed within the air flow channel 115 between the material portion 113 and the filter 109. The cylinder 111 is formed of a conductive material (e.g., copper) that preferably has a lower resistivity than the material forming the sensors 107. The cylinder 111 is spaced from the material portion 113 along the first axis such that the cylinder and the material portion 113 do not overlap each other along the first axis. Figure 2 The structure of the cylinder 111 is most clearly shown.

[0027] When the article 101 is placed in an oscillating magnetic field having a significant component aligned at least along the first axis in the direction A, the susceptor 107 undergoes resistive heating due to eddy currents induced in the oscillating magnetic field and / or releases heat when the permanent magnetization of the susceptor is continuously altered by a changing magnetic field. This causes the substrate 105 to heat up, thus generating an aerosol. At the same time, the changing magnetic field induces a current in the cylinder 111 that circulates around the first axis, thus generating a magnetic field opposite to the original magnetic field. Since the material portion 113 and the cylinder 111 are spaced apart from each other along the first axis, the original magnetic field remains relatively strong at the location of the susceptor 107, and thus a high heating rate can be achieved. However, outside the article 111, the opposing magnetic field substantially reduces the net intensity of the magnetic field, thus preventing the user from being exposed to an unacceptable high-intensity electromagnetic field. This will be further illustrated later with reference to Figure 6 To further illustrate this principle, the figure shows a specific example of the magnetic field source arrangement associated with the article 101 in the aerosol generating system.

[0028] Figure 3 is a cross-sectional view of a second embodiment of an aerosol generating article 301 according to the first aspect of the present invention. The aerosol generating article 301 includes a housing 103, an air flow channel 115, a material portion 11, and a filter 109, all as described above with reference to Figure 1 However, in this example, the conductive ring is provided by a ring 311 disposed within the air flow channel 115 between the material portion 113 and the filter 109. The ring 311 is located in a plane perpendicular to the first axis such that its orifice is aligned with the air flow channel 115. Similar to the cylinder 111 described above, the ring 311 is preferably made of a material (such as copper) having a lower resistivity than the susceptor 107. Although the ring shown in this example is directly adjacent to the filter 109, the ring can be located anywhere within the space between the material portion 113 and the filter 109, or can be arranged to surround the filter 109. The ring can also be located at either end of the article. More than one ring 311 can be provided.

[0029] Figure 4 shows a third embodiment of an aerosol generating article 401 according to the first aspect of the present invention. Similarly, this embodiment includes Figure 1All components of the aerosol-generating article 101 other than the cylinder 111. Instead, the conductive ring is provided by the foil 411 which is an integral layer of the housing 103. The foil 411 is formed of a conductive material such as copper or other metal and extends around the entire circumference of the housing 103. Although in this example the foil 411 is shown on the outside of the housing 103, the foil may be covered by an additional layer of material (e.g., paper) included in the housing. As an alternative to the foil 411, the conductive ring in this example may be provided by a grid, frame or mesh of conductive material. Importantly, the conductive ring, whether provided as the foil 411 or otherwise, allows current to circulate around the axis of the air flow channel 211.

[0030] After the housing 103 or the article 401 as a whole is manufactured, a configuration similar to that shown can be achieved by applying the foil 411 to the housing 103. Figure 4 the configuration shown.

[0031] Figure 5 A fourth embodiment of an aerosol-generating device 501 according to the first aspect of the present invention is shown. As in the previous example, the aerosol-generating article 501 includes a housing 103, a material section 113 and a filter 109 arranged as described above. In this example, the conductive ring is provided by a conductive layer 503 carried by the tipping paper 507 which is applied to the outside of the housing 103 at the location of the filter 109. The conductive layer 503 may be a metal foil or mesh and may be made of copper, for example. The conductive layer 503 is covered by a surface layer 505, such as a paper layer having the appearance of tipping paper on a conventional cigarette.

[0032] Figure 6 is a cross-sectional view of a part of an aerosol-generating system according to a second aspect of the present invention. The system includes an inductor 601 having the form of a helical coil. As described above with reference to Figure 1 the aerosol-generating article 101 is disposed inside the inductor and is arranged such that the cylindrical housing 103 and the inductor 601 are concentric about a first axis. When an alternating current passes through the inductor 601, an oscillating magnetic field is generated which is aligned in the direction of the first axis. As explained above, this magnetic field causes the susceptor 107 in the material section 113 to heat up and thus heat the substrate 105. The oscillating magnetic field also induces a current in the conductive cylinder 111 which circulates around the first axis, thereby generating an opposing magnetic field.

[0033] The magnetic field generated by the inductor 601 is strongest inside the coil, i.e., at the location where the receptor 107 is located. Since the cylinder 109 is spaced apart from the material portion along the first axis, the opposing magnetic field is not as strong at the location of the receptor 107. Thus, despite the presence of the opposing magnetic field, the receptor still experiences a significant net magnetic field. However, outside the coil, at a location a significant distance from the inductor 601 and the cylinder 109, the magnitudes of the original magnetic field and the opposing magnetic field are closer to each other. Therefore, relative to the case where there is no conductive loop provided by the cylinder 109, the magnitude of the net magnetic field at locations outside the article 101 and the inductor 601 is reduced.

[0034] Figure 6 The inductor 601 shown is part of a heating device that may also include additional features such as a power source to power the inductor 601, a chamber that contains the inductor 601 and from which the spent aerosol-generating article 101 can be removed, and a mouthpiece that allows a user to draw air through an air flow passage 115 to consume the aerosol generated by the substrate 105. Although the aerosol-generating system in this example includes Figure 1 the aerosol-generating article 101, this aerosol-generating article may replace any of the other exemplary aerosol-generating articles described herein.

Claims

1. An aerosol generating article, comprising: a housing extending along a first axis; a material portion disposed within the housing, wherein the material portion includes a substrate for generating an aerosol and one or more inductively heatable susceptors for heating the substrate; a conductive ring spaced from the material portion along the first axis and configured to generate a reverse magnetic field aligned relative to an oscillating magnetic field when there is an oscillating magnetic field substantially aligned along the first axis.

2. The aerosol-generating article according to claim 1, wherein The conductive ring is shaped as a ring in a plane substantially perpendicular to the first axis or as a hollow cylinder whose cylindrical axis is substantially aligned with the first axis.

3. The aerosol-generating article according to claim 1 or 2, wherein, The conductive ring comprises a metal.

4. The aerosol-generating article according to claim 3, wherein, The metal is copper.

5. The aerosol-generating article according to claim 1 or 2, wherein, The conductive ring is integral with the housing.

6. The aerosol-generating article according to claim 1 or 2, wherein, The conductive ring is carried by a tipping paper disposed on an outer surface of the housing.

7. The aerosol generating article according to claim 1 or 2, further comprising a filter for filtering the aerosol generated by the material portion.

8. The aerosol-generating article according to claim 7, wherein The conductive ring is disposed between the material portion and the filter.

9. The aerosol-generating article according to claim 1, wherein, The one or more inductively heatable susceptors comprise a first material and the conductive ring comprises a second material having a lower resistivity than the first material.

10. The aerosol-generating article according to claim 9, wherein, The first material is a metal.

11. The aerosol generating article according to claim 10, wherein the first material is aluminum.

12. The aerosol-generating article according to any one of claims 9 to 11, wherein, The second material is a metal.

13. The aerosol-generating article according to claim 12, wherein, The second material is copper.

14. An aerosol generating system, comprising: an aerosol generating article according to any one of the preceding claims; and a heating device including an inductor for generating an oscillating magnetic field substantially aligned along the first axis for heating the one or more inductively heatable susceptors.

15. The aerosol generating system according to claim 14, wherein, The heating device includes a chamber adapted to receive the aerosol generating article and hold the aerosol generating article in the oscillating magnetic field.

16. The aerosol generating system according to claim 14 or claim 15, wherein, The inductor includes an electrical coil.

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