AEROSOL-GENERATING DEVICE FOR INDUCTIVE HEATING OF AN AEROSOL-FORMING SUBSTRATE

Abstract

An aerosol-generating device for generating an aerosol by inductive heating of an aerosol-forming substrate is provided, the device including a device housing including a cavity configured to receive the aerosol-forming substrate; an induction source including an induction coil configured to generate an alternating magnetic field within the cavity, the induction coil being arranged around at least a portion of the cavity; a flux concentrator arranged around the induction coil and configured to distort the alternating magnetic field of the induction source towards the cavity; and a bond layer firmly coupled to a least a portion of the flux concentrator, the bond layer including or consisting of a poly(p-xylylene) polymer. There is also provided an aerosol-generating system including an aerosol-generating device including and an aerosol-generating article for the device, the article including an aerosol-forming substrate to be heated.

Claims

1.-15. (canceled)

16. An aerosol-generating device for generating an aerosol by inductive heating of an aerosol-forming substrate, the device comprising: a device housing comprising a cavity configured to receive the aerosol-forming substrate; an induction source comprising an induction coil configured to generate an alternating magnetic field within the cavity, wherein the induction coil is arranged around at least a portion of the cavity; a flux concentrator arranged around the induction coil and configured to distort the alternating magnetic field of the induction source towards the cavity; and a bond layer firmly coupled to a least a portion of the flux concentrator, wherein the bond layer comprises or consists of a poly(p-xylylene) polymer.

17. The aerosol-generating device according to claim 16, wherein the bond layer is a polymeric bond layer.

18. The aerosol-generating device according to claim 16, wherein the poly(p-xylylene) polymer is a chemical vapor deposited poly(p-xylylene) polymer.

19. The aerosol-generating device according to claim 16, wherein the bond layer is a coating covering at least a portion of a surface of the flux concentrator.

20. The aerosol-generating device according to claim 19, wherein the bond layer is a coating applied by evaporation to the flux concentrator.

21. The aerosol-generating device according to claim 16, wherein the bond layer has a layer thickness in a range between 50 nanometers and 200 micrometers.

22. The aerosol-generating device according to claim 16, wherein the flux concentrator is a tubular flux concentrator or a flux concentrator sleeve.

23. The aerosol-generating device according to claim 22, wherein the bond layer is firmly coupled to at least a portion of at least one of an inner surface or an outer surface of the tubular flux concentrator or the flux concentrator sleeve.

24. The aerosol-generating device according to claim 16, wherein the flux concentrator comprises a plurality of flux concentrator segments, and wherein each flux concentrator segment of the plurality of flux concentrator segments is provided with a respective bond layer, which is firmly coupled to a least a portion of the associated flux concentrator segment.

25. The aerosol-generating device according to claim 24, wherein the plurality of flux concentrator segments are tubular and arranged coaxially next to one another.

26. The aerosol-generating device according to claim 16, wherein the flux concentrator comprises a plurality of flux concentrator segments, and wherein the plurality of flux concentrator segments are elongate and arranged parallel to each other around a circumference of the flux concentrator.

27. The aerosol-generating device according to claim 16, wherein the bond layer covers the entire surface of the flux concentrator.

28. The aerosol-generating device according to claim 16, further comprising at least one susceptor element arranged at least partially within the cavity

29. An aerosol-generating system, comprising an aerosol-generating device according to claim 16 and an aerosol-generating article received or receivable at least partially in the cavity of the device, wherein the aerosol-generating article comprises the aerosol-forming substrate to be heated.

30. The aerosol-generating system according to claim 29, wherein the aerosol-generating article comprises at least one susceptor element positioned in thermal proximity to or thermal contact with the aerosol-forming substrate such that the susceptor element is inductively heatable by the induction source when the article is received in the cavity of the device.

Description

[0068] The invention will be further described, by way of example only, with reference to the accompanying drawings, in which:

[0069] FIG. 1 shows a schematic longitudinal cross-section of an aerosol-generating system in accordance with a first embodiment the present invention;

[0070] FIG. 2 is a detail view the induction module according to FIG. 1;

[0071] FIG. 3 shows a schematic longitudinal cross-section of a second embodiment of an induction module which can be alternatively used with the system according to FIG. 1;

[0072] FIG. 4 is a perspective view of the induction module of FIG. 3;

[0073] FIG. 5 shows a schematic longitudinal cross-section of a third embodiment of an induction module which can be alternatively used with the system according to FIG. 1; and

[0074] FIG. 6 is a perspective view of the induction module of FIG. 5.

[0075] FIG. 1 shows a schematic cross-sectional illustration of an exemplary embodiment of an aerosol-generating system 1 according to the present invention. The system 1 is configured for generating an aerosol by inductively heating an aerosol-forming substrate 91. The system 1 comprises two main components: an aerosol-generating article 90 including the aerosol-forming substrate 91 to be heated, and an aerosol-generating device 10 for use with the article 90 which comprises a receiving cavity 20 for receiving the article 90, and an inductive heater for heating the substrate 91 within the article 90 when the article 90 is inserted into the receiving cavity 20.

[0076] The article 90 has a rod shape resembling the shape of a conventional cigarette and comprises four elements arranged in coaxial alignment: an aerosol-forming substrate 91, a support element 92, an aerosol-cooling element 94, and a filter plug 95, the latter serving as a mouthpiece. The aerosol-forming substrate 91 may include, for example, a crimped sheet of homogenized tobacco material including glycerin as an aerosol-former. The support element 92 comprises a hollow core forming a central air passage 93. The filter plug 95 may, for example, include cellulose acetate fibers. All four elements are substantially cylindrical elements being arranged sequentially one after the other. The elements have substantially the same diameter and are circumscribed by an outer wrapper 96 made of cigarette paper such as to form a cylindrical rod.

[0077] The device 10 comprises a substantially rod-shaped main body 11 formed by a substantially cylindrical device housing. Within a distal portion 13, the device 10 comprises a power supply 16, for example a lithium ion battery, and an electric circuitry 17 including a controller for controlling operation of the device 10, in particular for controlling the heating process. Within a proximal portion 14 opposite to the distal portion 13, the device 10 comprises the receiving cavity 20. The receiving cavity 20 is open at the proximal end 12 of device 10, thus allowing the article 90 to be readily inserted into the receiving cavity 20.

[0078] A bottom portion 21 of the receiving cavity separates the proximal portion 14 of the device 10, in particular the receiving cavity 20, from the distal portion 13 of the device 10. Preferably, the bottom portion is made of a thermally insulating material, for example, PEEK (polyether ether ketone). Thus, electric components within the distal portion 13 may be kept separate from aerosol or residues produced by the aerosol generating process within the cavity 20.

[0079] The inductive heater of the device 10 comprises an induction source including an induction coil 31 for generating an alternating, in particular high-frequency magnetic field. In the present embodiment, the induction coil 31 is a helical coil circumferentially surrounding the cylindrical receiving cavity 20. The induction coil 31 is formed from a wire 38 and has a plurality of turns, or windings, extending along its length. The wire 38 may have any suitable cross-sectional shape, such as square, oval, or triangular. In this embodiment, the wire 38 has a circular cross-section. In other embodiments, the wire may have a flat cross-sectional shape.

[0080] The inductive heater further comprises a susceptor element 60 that is arranged within the receiving cavity such as to experience the magnetic field generated by the induction coil 31. In the present embodiment, the susceptor element 60 is a susceptor blade 61. With its distal end 64, the susceptor blade is arranged at the bottom portion 21 of the receiving cavity 20 of the device. From there, the susceptor blade 61 extends into the inner void of the receiving cavity 20 towards the opening of the receiving cavity 20 at the proximal end 12 of the device 10. The other end of the susceptor blade 60, that is, the distal free end 63 is tapered such as to allow the susceptor blade to readily penetrate the aerosol-forming substrate 91 within the distal end portion of the article 90.

[0081] When the device 10 is actuated, a high-frequency alternating current is passed through the induction coil 31. This causes the coil 31 to generate an alternating magnetic field within cavity 20. As a consequence, the susceptor blade 61 heats up due to at least one of eddy currents or hysteresis losses, depending on the magnetic and electric properties of the materials of the susceptor element 60. The susceptor 60 in turn heats the aerosol-forming substrate 91 of the article 90 to a temperature sufficient to form an aerosol. The aerosol may be drawn downstream through the aerosol-generating article 90 for inhalation by the user.

[0082] Preferably, the high-frequency magnetic field may be in the range between 500 kHz (kilo-Hertz) to 30 MHz (Mega-Hertz), in particular between 5 MHz (Mega-Hertz) to 15 MHz (Mega-Hertz), preferably between 5 MHz (Mega-Hertz) and 10 MHz (Mega-Hertz).

[0083] The induction coil 31 is part of an induction module 30 that is arranged with the proximal portion 14 of the aerosol-generating device 10. The induction module 30 has a substantially cylindrical shape that is coaxially aligned with a longitudinal center axis C of the substantially rod-shaped device 10. As can be seen from FIG. 1, the induction module 30 forms a least a portion of the cavity 20 or at least a portion of an inner surface of the cavity 20.

[0084] FIG. 2 shows the induction module 30 in more detail. Besides the induction coil 31, the induction module 30 comprises a tubular inner support sleeve 32 which carries the helically wound, cylindrical induction coil 31. At both ends, the tubular inner support sleeve 32 has a pair of annular protrusions 34 extending around the circumference of the inner support sleeve 32. The protrusions 34 are located at either end of the induction coil 31 to retain the coil 31 in position on the inner support sleeve 32. The inner support sleeve 32 may be made from any suitable material, such as a plastic. In particular, the inner support sleeve 32 may be a least a portion of the cavity 20, that is, at least a portion of an inner surface of the cavity 20.

[0085] Both the induction coil 31 and the inner support sleeve 32 are surrounded by a tubular flux concentrator 33 which extends along the length of the induction coil 31. The flux concentrator 33 is configured to distort the alternating magnetic field generated by the induction coil 31 during use of the device 10 towards the cavity 20. The flux concentrator 33 is fixed around the induction coil 31 and is also retained in position by the annular protrusions 34 of the inner support sleeve 32. The flux concentrator 33 is formed from a material having a high relative magnetic permeability of at least 5, preferably at least, at a frequency in a range between 6 MHz and 8 MHz and at a temperature of 25 degree Celsius. Due to this, the magnetic field produced by the induction coil 31 is attracted to and guided by the flux concentrator 33. Thus, the flux concentrator 33 acts as a magnetic shield. This may reduce undesired heating of or interference with external objects. The magnetic field lines within the inner volume defined by the induction module 30 are also distorted by flux concentrator 33 so that the density of the magnetic field within the cavity 20 is increased. This may increase the current generated within the susceptor blade 61 located in the cavity 20. In this manner, the magnetic field can be concentrated towards the cavity 20 to allow for more efficient heating of the susceptor element 60.

[0086] According to the invention, the device comprises a bond layer 40 that is firmly coupled to the flux concentrator 33 for keeping possible fragments of the flux concentrator 33 bonded in case of a breakage of the flux concentrator 33 into fragments. In the present embodiment, the bond layer 40 is provided as a parylene coating deposited on the surface of the flux concentrator 33 such that it extends over substantially the entire surface of the flux concentrator 33. However, it might be sufficient that the bond layer is only applied to one of the inner surface 35 or the outer surface 36 of the tubular flux concentrator 33.

[0087] Parylene is particularly suitable as bond layer material as it is chemical inert and thus approved for medical applications. In addition, parylene provides both, sufficient mechanical as well as thermal resistance. The parylene coating can be deposited by evaporation under vacuum to reach very thin layers. Advantageously, a thin bond layer 40 does not significantly increase the outer dimensions of the flux concentrator 33. In the present embodiment, the bond layer 40 has a layer thickness of about 50 micrometer. Parylene coatings can even fill possible pores in the surface of the flux concentrator 33.

[0088] In addition, the parylene bond layer 40 provides a corrosion protection of the flux concentrator 33 from the harsh environments in the cavity 20.

[0089] FIG. 3 and FIG. 4 illustrate an induction module 130 according to second embodiment of the invention. The induction module 130 is very similar to the induction module 30 according to FIG. 1 and FIG. 2. Therefore, like or identical features are denoted with the same reference numerals as in FIG. 1 and FIG. 2, yet incremented by 100. Unlike the flux concentrator 33 shown in FIG. 1 and FIG. 2, the induction module 130 according to the second embodiment comprises a flux concentrator 133 which is not a unitary component but is instead formed from a plurality of flux concentrator segments 137. The flux concentrator segments 137 are tubular and are positioned adjacent to one another as well as coaxially along the length of the flux concentrator 133. The flux concentrator segments 137 may have different relative magnetic permeability values. This allows the flux concentrator 133 to be “fine-tuned” to achieve a desired level of induction from the induction coil and a desired level of magnetic flux in the cavity. As with the induction module 30 of the first embodiment, the induction module 130 includes a tubular inner support sleeve 132 having annular protrusions 134 retaining the helically wound wire 138 of induction coil 131 and the flux concentrator segments 137 in position.

[0090] Each of the flux concentrator segments 137 is provided with a bond layer 140 such that each segment 137 is separately held together in case of breakage. In contrast to the previous embodiment, the bond layer 140 is a parylene coating that is deposited only on the inner surface 135 of each flux concentrator segment 137. Of course, the bond layer 140 may alternatively be applied such that it extends over substantially the entire surface of each segment 137.

[0091] FIG. 5 and FIG. 6 illustrate an induction module 230 according to a third embodiment of the invention. The induction module 230 is very similar to the induction module 130 according to FIG. 3 and FIG. 4. Therefore, like or identical features are denoted with the same reference numerals as in FIG. 3 and FIG. 4, yet incremented by 100. Unlike the flux concentrator 133 shown in FIG. 3 and FIG. 4, the induction module 230 comprises a flux concentrator 233 which comprises a plurality of elongate flux concentrator segments 237. The elongate flux concentrator segments 237 are positioned around the circumference of the flux concentrator 233 such that their longitudinal axes are substantially parallel with the magnetic axis of the induction coil 231. The induction module 230 further comprises an outer support sleeve 239 which circumscribes the induction coil 231 and is used to retain the flux concentrator segments 237 in position. To this end, the outer support sleeve 239 includes a plurality of longitudinal slots within which the flux concentrator segments are slidably held. The outer support sleeve 239 has a circular, cylindrical shape. Accordingly, the flux concentrator segments 237 have an arc-shaped cross-section corresponding to the outer shape of the outer support sleeve 239. The longitudinal slots have a length which is greater than the length of the flux concentrator segments 237. As a result, the flux concentrator segments 237 may each be slid within their respective slot to vary their respective longitudinal position while remaining within their respective slots. This allows the magnetic field to be tuned by varying the longitudinal position of one or more of the elongate flux concentrator segments 237. In this example, the flux concentrator segments 237 are arranged on the outer support sleeve 239 such that they are separated by a narrow gap. In other examples, two or more of the flux concentrator segments may be in direct contact with one or both of the flux concentrator segments on either of its sides. As with the induction modules 30, 130 of the first and second embodiment, the induction module 230 of the third embodiment also includes an inner support sleeve 232 having annular protrusions 234 which retain the induction coil 231, the outer support sleeve 239 and the flux concentrator 233 in position.

[0092] Each of the flux concentrator segments 237 is provided with a bond layer 240 such that each segment 237 is separately held together in case of breakage. In contrast to the previous embodiment, the bond layer 240 is a parylene coating that is deposited such that it extends over substantially the entire surface of each segment 237.

[0093] In all three embodiments according to in FIG. 1-6, the bond layer 40, 140, 240 is applied to the respective flux concentrator 33, 133, 233 prior to assembling the induction module 30, 130, 230.