Aerosol-generating items

Abstract

An aerosol-generating article (101) is described, comprising: a shell (103) extending along a first axis; a material portion (113) disposed within the shell, the material portion (113) including a substrate (105) for generating an aerosol and one or more inductively heatable susceptors (107) for heating the substrate (105); and a conductive loop (111) spaced apart from the material portion (113) along the first axis and configured to generate, in the presence of an oscillating magnetic field aligned substantially along the first axis, a counter-magnetic field that is aligned opposite to the oscillating magnetic field.

Description

[Technical Field]

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

[0002] Aerosol-generating devices have become popular as alternatives to traditional combustible tobacco products. Heated tobacco products, also known as heat-not-burn products, are a class of aerosol-generating devices that are configured to heat a tobacco substrate to a temperature sufficient to generate an aerosol from the substrate, but not so high that the tobacco burns. While this specification refers specifically to heated tobacco products, it will be understood that the following discussion applies equally 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 susceptors couple to the magnetic field to generate heat, which in turn heats the substrate. The rate at which the substrate heats depends on the strength of the magnetic field at the location of the susceptor, but safety concerns regarding the strength of the electromagnetic field to which users are exposed limit the strength of the magnetic field that can be generated by such devices, and therefore the heating rate that can be achieved.

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

[0005] A first aspect of the present invention provides an aerosol-generating article comprising: a shell extending along a first axis; a material portion disposed within the shell, the material portion including a substrate for generating an aerosol and one or more inductively heatable susceptors for heating the substrate; and a conductive loop spaced from the material portion along the first axis and configured to generate, in the presence of an oscillating magnetic field aligned substantially along the first axis, an opposing magnetic field aligned opposite to the oscillating magnetic field.

[0006] The opposing magnetic field generated by the conductive loop has the effect of reducing the net external magnetic field strength in the area surrounding the item. As a result, when the item is inductively heated by an oscillating magnetic field (e.g., supplied by a coil placed inside the item), the electromagnetic field strength to which the user is exposed is reduced compared to that which would be experienced without the conductive loop in place. The present invention provides a further advantage in that it allows for the elimination of the need for electromagnetic shielding within the device that provides the oscillating magnetic field, thereby simplifying the assembly of the device.

[0007] The conductive loop may be formed of any suitable conductive material, such as copper, silver, or aluminum. The conductive loop may be any conductive structure that allows a current to circulate about the first axis to establish a counter magnetic field.

[0008] In some preferred embodiments, the conductive loop is shaped as a ring that lies in a plane substantially perpendicular to the first axis, or as a hollow cylinder with its cylindrical axis substantially aligned with the first axis. As a result, the openings in the ring or cylinder will be aligned along the same direction as the airflow passage, minimizing obstruction of the passage by the conductive loop. The ring or cylinder can have a solid surface, but can alternatively be formed of a grid or mesh of conductive material.

[0009] Preferably, the conductive loop comprises a metal, most preferably copper or silver. However, the conductive loop can also incorporate other conductive materials, such as graphite or conductive polymers. Metals, particularly copper and silver, are generally highly conductive and therefore capable of efficiently generating a strong counter magnetic field when placed in an oscillating primary magnetic field. Moreover, highly conductive materials such as metals are preferred because they prevent current induced in the conductive loop from generating excessive amounts of heat through resistive heating.

[0010] In some preferred embodiments, the conductive loop is integral with the shell. For example, the conductive loop can be a layer of conductive material inside the shell, or it can be attached to the exterior of the shell. In other preferred embodiments, the conductive loop is supported by tipping paper disposed on the exterior surface of the shell. In the latter case, the conductive loop can be integral with the tipping paper (e.g., as an interior layer of the tipping paper or attached to the exterior of the tipping paper).

[0011] The aerosol-generating article preferably includes a filter for filtering the aerosol generated by the substrate. The filter may be disposed, for example, within the airflow passage. The filter may be configured to filter any potentially harmful substances from the aerosol and may cool the aerosol passing through it. In a particularly preferred embodiment, the conductive loop 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 loop comprises a second material having a lower resistivity than the first material. A high conductivity of the conductive loop is advantageous because it ensures a relatively strong counter magnetic field, minimizing heating of the loop due to induced currents. Conversely, because it is desirable for the susceptor to heat up quickly in the presence of an oscillating magnetic field, a relatively low conductivity of the inductively heatable susceptor material is advantageous. For example, the first material could be aluminum, and the second material could be copper. However, in other embodiments, the first and second materials could be the same; for example, both could be aluminum.

[0013] A second aspect of the present invention provides an aerosol generation system comprising an aerosol-generating article according to the first aspect of the present invention and a heating device including an inductor for generating an oscillating magnetic field aligned substantially along a first axis to heat one or more inductively heatable susceptors. The heating device may be a handheld device that facilitates 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 a chamber through which the aerosol may be drawn from the article by a user. As discussed above, the presence of a conductive loop in the aerosol-generating article simplifies assembly of the heating device, as it does not require electromagnetic shielding to protect the user from high electromagnetic fields.

[0014] In a preferred implementation, the heating device includes a chamber adapted to receive the aerosol-generating article and hold the aerosol-generating article within an oscillating magnetic field.

[0015] Advantageously, the inductor comprises an electrically powered coil, e.g., a helical coil. When current flows through such a coil, the magnetic field generated within it can be strong and highly uniform, since the magnetic field lines run parallel to one another along the axis around which the coil is wound. As such, the coil can be adapted so that the airflow passage is preferably concentric with the coil, allowing the aerosol-generating article to be disposed within it.

[0016] Examples of aerosol-generating articles and aerosol-generating systems will now be described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a first embodiment of an aerosol-generating article according to a first aspect of the present invention; [Figure 2] 2 shows an exemplary conductive loop suitable for incorporation into the aerosol-generating article of FIG. 1. [Figure 3] 1 is a cross-sectional view of a second embodiment of an aerosol-generating article according to a first aspect of the present invention. [Figure 4] FIG. 2 is a cross-sectional view of a third embodiment of an aerosol-generating article according to the first aspect of the present invention. [Figure 5] FIG. 2 is a cross-sectional view of a fourth embodiment of an aerosol-generating article according to the first aspect of the present invention. [Figure 6] FIG. 2 is a cross-sectional view of an aerosol generation system according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1 is a cross-sectional view of an aerosol-generating article 101 according to a first embodiment of the present invention. The article 101 is surrounded by a cylindrical shell 103 that defines an airflow passage 115. The airflow passage 115 extends along a first axis that is oriented along the direction labeled A in this drawing.

[0019] Within the shell 103 is a material portion 113 at one end of the airflow passage 115. The material portion 113 includes a substrate 105, which includes a material such as reconstituted tobacco that, when heated, generates an aerosol for consumption by inhalation. The material portion 113 also includes a plurality of inductively heatable susceptors 107 embedded in the substrate 105. The susceptors 107 may be made of, for example, aluminum. Other suitable materials include iron, nickel, stainless steel, or alloys (e.g., nickel-chromium or nickel-copper). In this example, each susceptor 107 has the form of an elongated strip or rod arranged to extend along the airflow passage 115 in the direction of the first axis A.

[0020] At the other end of the airflow passage 115 is a filter 109. As the aerosol generated by the substrate 105 is drawn through the airflow passage 115 along the direction of the first axis A, it passes through the filter 109, which cools the aerosol. The filter 109 may also be configured to filter any unwanted or potentially harmful materials from the aerosol.

[0021] A conductive loop in the form of a hollow cylinder 111 is disposed within airflow passage 115 between material portion 113 and filter 109. Cylinder 111 is preferably formed of a conductive material having a lower resistivity than the material from which susceptor 107 is formed, such as copper. Cylinder 111 is spaced apart from material portion 113 along the first axis such that cylinder 111 and material portion 113 do not overlap one another along the first axis. Figure 2 most clearly illustrates the structure of cylinder 111.

[0022] When the article 101 is placed in an oscillating magnetic field having at least a substantial component aligned along the first axis, A, the susceptor 107 undergoes resistive heating due to eddy currents induced in the susceptor 107 and / or heat released as the susceptor's permanent magnetization is continuously altered by the changing magnetic field. This causes the substrate 105 to heat up and thus generate an aerosol. At the same time, the changing magnetic field induces currents in the cylinder 111, which circulate around the first axis and thus generate a magnetic field that opposes the original magnetic field. Because 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 susceptor 107, thereby achieving high heating rates. However, outside the article 111, the opposing magnetic field substantially reduces the net strength of the magnetic field, thereby preventing users from being exposed to unacceptably high-intensity electromagnetic fields. This principle is further illustrated below with reference to FIG. 6, which shows a particular example of the placement of a magnetic field source relative to an article 101 in an aerosol-generating system.

[0023] FIG. 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 the shell 103, the airflow passage 115, the material portion 113, and the filter 109, all as described above with reference to FIG. 1. However, in this example, the conductive loop is provided by a ring 311 disposed within the airflow passage 115 between the material portion 113 and the filter 109. The ring 311 lies in a plane perpendicular to the first axis, with its opening aligned with the airflow passage 115. Like the cylinder 111 described above, the ring 311 is preferably made of a material having a lower resistivity than the susceptor 107, such as copper. While the ring is shown directly adjacent to the filter 109 in this example, it could be positioned anywhere in the space between the material portion 113 and the filter 109, or it could be positioned to surround the filter 109. It could also be positioned at either end of the article. More than one ring 311 could also be provided.

[0024] FIG. 4 shows a third embodiment of an aerosol-generating article 401 according to the first aspect of the present invention. Again, this embodiment includes all of the components of the aerosol-generating article 101 of FIG. 1, except for the cylinder 111. Instead, the conductive loop is provided by a foil 411 that is an integral layer of the shell 103. The foil 411 is formed of a conductive material, such as copper or another metal, and extends around the entire circumference of the shell 103. In the example, the foil 411 is shown on the exterior of the shell 103, but it could also be covered by an additional layer of material (e.g., paper) that the shell comprises. As an alternative to the foil 411, the conductive loop in this example could also be provided by a grid, frame, or mesh of conductive material. What is important is that the conductive loop, whether provided as a foil 411 or otherwise, allows electrical current to circulate around the axis of the airflow passage 211.

[0025] A configuration similar to that shown in FIG. 4 can also be achieved by applying foil 411 to shell 103 after shell 103 has been manufactured or after the entire article 401 has been manufactured.

[0026] Figure 5 shows a fourth embodiment of an aerosol-generating device 501 according to the first aspect of the present invention. As in the previous examples, the aerosol-generating article 501 comprises a shell 103, a material portion 113 and a filter 109 arranged in the manner described above. In this example, the conductive loop is provided by a conductive layer 503 supported by tipping paper 507 attached to the exterior of the shell 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, for example a paper layer having the appearance of tipping paper on a conventional cigarette.

[0027] Figure 6 is a cross-sectional view of a portion of an aerosol-generating system according to a second embodiment of the present invention. The system includes an inductor 601 in the form of a helical coil. An aerosol-generating article 101, as described above with reference to Figure 1, is disposed inside the inductor, with the cylindrical shell 103 and the inductor 601 concentric about a first axis. When an alternating current is applied to the inductor 601, an oscillating magnetic field aligned along the first axis is generated. As explained above, this magnetic field heats the susceptor 107 in the material portion 113, thereby heating the substrate 105. The oscillating magnetic field also induces a current circulating around the first axis in the conductive cylinder 111, which generates a counter magnetic field.

[0028] The magnetic field generated by the inductor 601 is strongest inside the coil where the susceptor 107 is located. Because the cylinder 109 is spaced apart from the material along the first axis, the counter magnetic field is not as strong at the location of the susceptor 107. As a result, the susceptor experiences a significant net magnetic field despite the presence of the counter magnetic field. However, outside the coil, at locations equally distant from the inductor 601 and the cylinder 109, the magnitudes of the original and counter magnetic fields approach each other. Thus, the net magnetic field at locations outside the article 101 and inductor 601 is reduced in magnitude compared to the case in the absence of the conductive loop provided by the cylinder 109.

[0029] 6 is part of a heating device, which may also include additional features such as a power source for powering the inductor 601, a chamber for housing the inductor 601 and from which the aerosol-generating article 101 can be removed when ready for use, and a mouthpiece that allows a user to draw air through the airflow passage 115 to consume the aerosol generated by the substrate 105. The aerosol-generating system in this example includes the aerosol-generating article 101 of FIG. 1, although this may be replaced with any of the other exemplary aerosol-generating articles described herein.

Claims

1. a shell extending along a first axis; a material portion disposed within the shell, the material portion including a substrate for generating an aerosol and one or more inductively heatable susceptors for heating the substrate; a conductive loop spaced apart from the material along the first axis and configured to, in the presence of an oscillating magnetic field aligned substantially along the first axis, generate an opposing magnetic field aligned opposite to the oscillating magnetic field; 1. An aerosol-generating article comprising:

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

3. 3. An aerosol-generating article according to claim 1 or 2, wherein the conductive loop comprises a metal, preferably copper.

4. 4. The aerosol-generating article according to claim 1, wherein the conductive loop is integral with the shell.

5. 4. The aerosol-generating article according to claim 1, wherein the conductive loop is supported by tipping paper disposed on the outer surface of the shell.

6. 5. The aerosol-generating article according to claim 1, further comprising a filter for filtering the aerosol generated by the material portion.

7. The aerosol-generating article of claim 6 , wherein the conductive loop is disposed between the material portion and the filter.

8. 8. An aerosol-generating article according to any one of claims 1 to 7, wherein the one or more inductively heatable susceptors comprise a first material and the conductive loop comprises a second material having a lower resistivity than the first material.

9. 9. An aerosol-generating article according to claim 8, wherein the first material is a metal, preferably aluminium.

10. 10. An aerosol-generating article according to claim 8 or 9, wherein the second material is a metal, preferably copper.

11. An aerosol-generating article according to any one of claims 1 to 10; a heating device including an inductor for generating an oscillating magnetic field aligned substantially along the first axis for heating the one or more inductively heatable susceptors; 1. An aerosol generating system comprising:

12. 12. The aerosol generating system of claim 11, wherein the heating device includes a chamber adapted to receive the aerosol-generating article and hold the aerosol-generating article within the oscillating magnetic field.

13. 13. The aerosol generating system of claim 11 or 12, wherein the inductor comprises an electrically powered coil.

Images