Patent ID: 12245633

FIG.1shows a schematic cross-sectional illustration of a first exemplary embodiment of an aerosol-generating system1according to the present invention. The system1is configured for generating an aerosol by inductively heating an aerosol-forming substrate97. The system1comprises two main components: an aerosol-generating article90including the aerosol-forming substrate97to be heated, and an aerosol-generating device10for use with the article90. The device10comprises a cavity20for receiving the article90, and an inductive heating arrangement30for heating the substrate97within the article90when the article90is received in the cavity20.

The article90has a rod shape resembling the shape of a conventional cigarette. In the present embodiment, the article90comprises four elements arranged in coaxial alignment: a substrate element91, a support element92, an aerosol-cooling element94, and a filter plug95. The substrate element is arranged at a distal end of the article90and comprises the aerosol-forming substrate to be heated. The aerosol-forming substrate97may include, for example, a crimped sheet of homogenized tobacco material including glycerin as an aerosol-former. The support element92comprises a hollow core forming a central air passage93. The filter plug95serves as a mouthpiece and may include, for example, 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 wrapper96made of cigarette paper such as to form a cylindrical rod. The outer wrapper96may be wrapped around the aforementioned elements so that free ends of the wrapper overlap each other. The wrapper may further comprise adhesive that adheres the overlapped free ends of the wrapper to each other.

The device10comprises a substantially rod-shaped main body11formed by a substantially cylindrical device housing19. Within a distal portion13, the device10comprises a power supply16, for example a lithium ion battery, and an electric circuitry17including a controller for controlling operation of the device10, in particular for controlling the heating process. Within a proximal portion14opposite to the distal portion13, the device10comprises the cavity20. The cavity20is open at the proximal end12of device10, thus allowing the article90to be inserted into the cavity20.

A bottom portion21of the cavity separates the distal portion13of the device10from the proximal portion14, in particular from the cavity20. Preferably, the bottom portion is made of a thermally insulating material, for example, PEEK (polyether ether ketone). Thus, electric components within the distal portion13may be kept separate from aerosol or residues produced by the aerosol generating process within the cavity20.

The inductive heating arrangement30comprises an induction coil31for generating an alternating, in particular high-frequency magnetic field within the cavity20. 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). In the present embodiment, the induction coil31is a helical coil circumferentially surrounding the cylindrical cavity20along its length axis. The induction coil31is formed by a plurality of turns of a composite cable32which comprises a multi-wire electrical conductor33. Details of the composite cable32will be described further below, in particular with reference toFIG.3-18.

The inductive heating arrangement30further comprises a susceptor60that is arranged within the cavity20such as to experience the magnetic field generated by the induction coil31. In the present embodiment, the susceptor60is a susceptor blade61. With its distal end64, the susceptor blade is arranged at the bottom portion21of the cavity20of the device. From there, the susceptor blade61extends into the inner void of the cavity20towards the opening of the cavity20at the proximal end12of the device10. The other end of the susceptor blade60, that is, the distal free end63is tapered such as to allow the susceptor blade to readily penetrate the aerosol-forming substrate97within the distal end portion of the article90.

Alternatively, as shown inFIG.2, the susceptor60may be part of the aerosol-generating article90. Here, the susceptor99is a susceptor strip made of a susceptive material that is embedded within the aerosol-forming substrate97of the article90. The susceptor strip99is arranged such as to extend long the center of the substantially cylindrical article90. Apart from that, the embodiment of the aerosol-generating system according toFIG.2is identical to the embodiment of the aerosol-generating system according toFIG.1. Therefore, identical or similar features are denoted with identical reference numbers.

With reference to both embodiments, the inductive heating process is as follows: When the device10is actuated, a high-frequency alternating current is passed through the induction coil31. Since the coil is arranged around the cavity20, the alternating current through the coil causes an alternating magnetic field within the cavity20. Depending on the magnetic and electric properties of the respective susceptor material, the alternating magnetic field induces at least one of eddy currents or hysteresis losses in the susceptor blade61or the susceptor strip99, respectively. As a consequence, the susceptor blade61or the susceptor strip99, respectively, is heated up until reaching a temperature that is sufficient to form an aerosol from the substrate97that is in thermal proximity or direct physical contact thereto. The generated aerosol may be drawn downstream through the aerosol-generating article90for inhalation by the user.

As can be seen inFIG.1andFIG.2, the induction coil31is part of an induction module40that is arranged with the proximal portion14of the aerosol-generating device10. The induction module40has a substantially cylindrical shape that is coaxially aligned with a longitudinal center axis71of the rod-shaped device10. As can be seen fromFIG.1, the induction module40forms a least a portion of the cavity20or at least a portion of an inner surface of the cavity20.

FIG.3shows the induction module40in more detail. Besides the induction coil31, the induction module40comprises a tubular support sleeve42which carries the helically wound, cylindrical induction coil31. At its inner surface, the tubular support sleeve42comprises an annular recess41in which the cylindrical induction coil31is received. Accordingly, both end portions44of the support sleeve42protrude radially inwards towards the center axis71such as to retain the induction coil31in position in the recess of the support sleeve42. The support sleeve42may be made from any suitable material, such as a plastic. In particular, the support sleeve42may form a least a portion of the cavity20, that is, at least a portion of an inner surface of the cavity20.

FIG.4shows a second embodiment of the induction module40. Here, the tubular support sleeve42comprises an annular recess43at its outer surface in order to receive the cylindrical induction coil31therein. Accordingly, both end portions44of the support sleeve42protrude radially outwards away from the center axis71such as to retain the induction coil31in position in the recess43.

FIG.5shows a third embodiment of the induction module40. The induction module40is nearly identical to the module according toFIG.4. In addition, the induction module40of the third embodiment comprises a susceptor sleeve6942that is surrounded by the induction coil32. That is, the susceptor sleeve69is part of the aerosol-generating device but not of the aerosol-generating article. The susceptor sleeve69is arranged in an annular recess45at the inner surface of the support sleeve. Hence, the susceptor sleeve69forms at least a portion of an inner surface of the cavity20. Accordingly, when an article is inserted in the cavity, the susceptor sleeve69surrounds the substrate element91in order to heat the aerosol-forming substrate from outside. In this configuration, the susceptor sleeve69acts an oven heater. This is in contrast to the embodiments shown inFIG.1andFIG.2where the susceptor blade61or the susceptor strip99, respectively, heats the aerosol-forming substrate from inside.

FIG.6shows the composite cable32used to form the induction coil31of the devices10shown inFIG.1andFIG.2in more detail. The composite cable32comprises an electrical conductor33for carrying the current used to generate the magnetic field. The conductor33is fully embedded in an insulating conductor encasement34in order to electrically insulate adjacent turns of the induction coil from each other and thus to prevent a short circuit. According to the invention, the conductor33comprises a plurality of non-insulated wires35in electrical contact with each other. In the present embodiment, the conductor33comprises in total twenty-two wires35which are arranged in two layers on top of each other, wherein each layer comprises eleven wires35. The layers are aligned such that wires35of one layer are arranged in grooves formed between adjacent wires35of the other layer. Accordingly, the assembly of all the wires35forms an electrical conductor33having a substantially trapezoid cross-section.

Each wire35may have a diameter in a range between 0.25 millimeter and 0.75 millimeter, for example 0.5 millimeter. Accordingly, the width dimension33.1of the electrical conductor33is given by eleven-and-half times the wire diameter. That is, the width dimension33.1of the electrical conductor33may be in range between 2.875 millimeter and 8.625 millimeter, for example 5.75 millimeter. Likewise, the thickness dimension33.2of the electrical conductor33is given by about 1.73 times the wire diameter. That is, the width dimension33.1of the electrical conductor33may be in range between about 0.4 millimeter and about 1.3 millimeter, for example about 6.5 millimeter. In the present embodiment, the width dimension of the electrical conductor33corresponds to a maximum dimension of the cross-section of the electrical conductor perpendicular to a radial direction70(see dashed-dotted arrow inFIG.4-6) with respect to the plurality of turns of the composite cable. Likewise, the thickness dimension of the electrical conductor33corresponds to a maximum dimension of a cross-section of the electrical conductor33in a radial direction70(see dashed-dotted arrow inFIG.4-6) with respect to the plurality of turns of the composite cable32. As the width dimension33.1of the electrical conductor33is much larger than its thickness dimension33.2, the electrical conductor33may be denoted as a flat electrical conductor33.

The same holds for the entire cable32which also has a width dimension32.1that is much larger than its thickness dimension32.2. Accordingly, the composite cable32may be denoted as a flat composite cable32. In the present embodiment, the width dimension32.1of the composite cable32, that is, a maximum dimension of the cross-section of the composite cable32perpendicular to a radial direction70(see dashed-dotted arrow inFIG.4-6) with respect to the plurality of turns of the composite cable3231, may be in a range between 1 millimeter and 7 millimeter, in particular between 1.5 millimeter and 5 millimeter. Likewise, the thickness dimension32.2of the composite cable32, that is, wherein a maximum dimension of the cross-section of the composite cable32in a radial direction70(see dashed-dotted arrow inFIG.4-6) with respect to the plurality of turns of the composite cable, may be in a range between 0.5 millimeter and 9 millimeter, in particular between 0.7 millimeter and 9 millimeter, preferably between 0.9 millimeter and 5 millimeter. The outer cross-section of the composite cable32is substantially rectangular which rounded edges.

Upon being arranged around the cavity20, the composite cable32comprises a first side38facing inwards towards the cavity20and a second side39opposite to the first side facing outwards away from the cavity20. This is indicated inFIG.6which shows a section of the composite cable in the winding configuration.

As can be further seen inFIG.6, the electrical conductor33is arranged substantially symmetrically with respect to a first axis of symmetry32.3of the outer cross-section of the cable32which extends between the first side38and the second side39in the radial direction70. In contrast, the electrical conductor33is arranged asymmetrically with regard to a second axis of symmetry32.4of the outer cross-section of the composite cable32such as to be closer to the first side38of the composite cable than to the second side39. That is, the insulating conductor encasement34is mainly located towards the second side39of the composite cable and thus radially further outside than the electrical conductor33. In particular, the electrical conductor33is arranged between the first side38and the second axis of symmetry. Due to this, the insulating conductor encasement34may act as a protective sheath surrounding the conductor33when the composite cable32is arranged around the cavity. Here, a minimum distance33.8between the conductor33and the first side38is at most in a range between 0.1 millimeter and 0.5 millimeter, in particular between 0.1 millimeter and 0.3 millimeter.

In addition, the insulating conductor encasement34may serve other purposes. In the present embodiment, the insulating conductor encasement34comprises a magnetic flux concentrator material in order to concentrate or focus the magnetic field within the cavity20. Advantageously, this increases the level of heat generated in the susceptor for a given level of power passing through the induction coil31in comparison to induction coils having no flux concentrator. Thus, the efficiency of the aerosol-generating device10is improved. Furthermore, by distorting the magnetic field towards the cavity, the magnetic flux concentrator material of the insulating conductor encasement34reduces the extent to which the magnetic field propagates beyond the induction coil31. That is, the flux concentrator material of the insulating conductor encasement34acts as a magnetic shield. Advantageously, this may reduce undesired interference of the magnetic field with other susceptive parts of the aerosol-generating device10, for example with a metallic outer housing, or with susceptive external items in close proximity to the device10. In particular, integrating a magnetic flux concentrator material in the composite cable32allows for providing both the induction coil31and an appropriate magnetic flux concentrator in one part. Advantageously, this reduces the effort required to manufacture the aerosol-generating device10both in terms of costs and time. As an example, the insulating conductor encasement34may comprise or may be made of a lamination, a pure ferrite or a proprietary iron- or ferrite based composition. Here, the insulating conductor encasement34is made of Alphaform MF available from Fluxtrol Inc., 1388 Atlantic Blvd. Auburn Hills, MI 48326 USA. Alphaform MF is formable soft magnetic composite developed on the basis of magnetic particles with a thermal-curing epoxy binder which is suitable or frequencies between 10 kilo-Hertz and 1000 kilo-Hertz.

Advantageously, the wires35of conductor33are embedded in the material of the insulating conductor encasement34by extrusion or lamination.

FIG.7shows a second embodiment of the composite cable32which is very similar to the first embodiment of the composite cable32as shown inFIG.6. Therefore, identical or similar features are denoted with identical reference numbers. In contrast to the first embodiment, the composite cable32according toFIG.7comprises a conductor33which consists of a single layer of seven wires35. Each of the seven wires35has larger diameter than the wires35shown inFIG.6. The diameter is chosen such that the cross-sectional area of the electrical conductor33inFIG.7, that is, the sum of the cross-sectional areas of all seven wires35, substantially corresponds to the cross-sectional area of the electrical conductor33inFIG.6, that is, to the sum of the cross-sectional area of all twenty-two wires35. Thus, the composite cable32shown inFIG.6and the composite cable32shown inFIG.7have substantially the same electrical properties, in particular substantially the same electrical resistance. However, the composite cable32according toFIG.6is more flexible due to the larger number and smaller diameter of the wires35.

FIG.8-10show three further embodiments of the composite cable132. In all three embodiments, the composite cable132is realized as a multi-layer composite cable132which comprises an electrically insulating conductor encasement layer134forming the insulating conductor encasement as described above and, addition to that, a support layer136. Both layers134,136fully enclose the electrical conductor133. Advantageously, the different layers may be attached to each other by means of a lamination process.

The support layer136serves to increase the mechanical resistance of the composite cable134. In order not to affect the induction performance of the magnetic field generated by the current through the electrical conductor132, the support layer136is electromagnetically inert in all three embodiments. For example, the support layer136may be made of polyetheretherketone or polyaryletherketone, both of which are electromagnetic inert materials.

In all three embodiments, the respective support layer136is an edge layer, in particular an edge layer forming the first side138of the composite cable132.

In the embodiments shown inFIGS.8and9, the electrical conductor133is at least partially embedded in the respective support layer136and partially embedded in the insulating conductor encasement layer134. Apart from the support layer136and the partial embedment in the insulating conductor encasement layer, the composite cables132shown inFIGS.8and9are very similar to the composite cables32shown inFIGS.6and7, respectively. Therefore, identical or similar features are denoted with the same reference signs, yet incremented by 100.

In contrast, in the embodiment shown inFIG.10, the electrical conductor133is not embedded in the support layer136. Instead, the support layer136covers that side of the electrical conductor133which faces inwards towards the cavity when the composite cable132is arranged around the cavity20. Accordingly, the support layer136is thinner than the support layer136inFIGS.8and9. Further in contrast to the embodiments shown inFIGS.8and9, the insulating conductor encasement layer134of the cable132shown inFIG.10consists of three parts: a first part134.1arranged on a side of the conductor133opposite to the first side138as well as a second part134.2and a third part134.3arranged laterally to the narrow sides of the flat conductor133. Furthermore, the composited cable132according toFIG.10does not have rounded edges, but rather sharp edges.

In the embodiments according toFIGS.8and9, the support layer136may have a layer thickness in a range between 0.1 millimeter and 1 millimeter, in particular between 0.2 millimeter and 0.5 millimeter. Likewise, in the embodiment according toFIG.10, the support layer136may have a layer thickness in range between 0.25 millimeter and 1 millimeter, in particular between 0.25 millimeter and 0.5 millimeter.

The insulating conductor encasement layer134may have a total layer thickness in a range between 0.5 millimeter and 7 millimeter, in particular between 0.7 millimeter and 4 millimeter or between 0.7 millimeter and 3 millimeter, or in a range between 0.4 millimeter and 7.2 millimeter, in particular between 0.45 millimeter and 2.6 millimeter. Likewise, a portion of the insulating conductor encasement layer134embedding the conductor on a side opposite to the first side, in particular the first part134.1, may have a thickness in a range between 0.2 millimeter and 5 millimeter, in particular 0.2 millimeter and 1.5 millimeter.

FIG.11-13show yet another three embodiments of the composite cable232which are similar to the embodiments shown inFIG.8-10. Therefore, identical or similar features are denoted with the same reference signs, yet incremented by 100. In contrast to the embodiments shown inFIG.8-10, the composite cables232shown inFIG.11-13additionally comprise a shield layer237arranged on top of the insulating conductor encasement layer234opposite to the support layer236. The shield layer237primarily serves to reduce adverse effects of the magnetic field in regions outside the shield layer237and, vice versa, to reduce distortion of the magnetic field by electrically conductive or highly magnetically susceptible materials in the immediate vicinity of the device, or in the housing of the device itself. Accordingly, the shield layer237preferably comprises a conductive material, such as a metal coating applied on a side of the electrically insulating conductor encasement layer facing outwards away from the cavity. This can be further seen fromFIG.11-13, the respective shield layer237is an edge layer forming the second side239of the multi-layer composite cable232.

The shield layer237may have a layer thickness in a range between 0.3 millimeter and 3 millimeter, in particular between 0.3 millimeter and 2 millimeter.

To compensate for the additional layer237, the layer thickness of the insulating conductor encasement layer234in the embodiments shown inFIG.11-13may be different from the respective layer thicknesses in the embodiments shown inFIG.8-10. Accordingly, the insulating conductor encasement layer of the embodiments shown inFIG.11-13may have a total layer thickness in a range between 0.2 millimeter and 6 millimeter, in particular between 0.4 millimeter and 2 millimeter, or in a range between 0.4 millimeter and 9.2 millimeter, in particular between 0.45 millimeter and 3.1 millimeter. Likewise, a portion of the insulating conductor encasement layer234embedding the conductor on a side opposite to the first side, in particular the first part234.1, may have a thickness in a range between 0.2 millimeter and 7 millimeter, in particular 0.2 millimeter and 2 millimeter.

FIG.14-16show yet another three embodiments of the composite cable332which are similar to the embodiments shown inFIG.11-13. Therefore, identical or similar features are denoted with the same reference signs, yet incremented by 100. In contrast to the embodiments shown inFIG.11-13, the composite cables332shown inFIG.14-16comprises a flux concentrator layer337, instead of a shield layer. For example, the flux concentrator layer337may comprise a ferrite material. The ferrite material acts as flux concentrator material. Furthermore, the layer thicknesses are slightly different to those of the embodiment shown inFIG.11-13. Here, the insulating conductor encasement layer334of the embodiments shown inFIG.14-16may have a total layer thickness in range between 0.15 millimeter and 3 millimeter, in particular between 0.3 millimeter and 1 millimeter, or in a range between 0.45 millimeter and 3.7 millimeter, in particular between 0.5 millimeter and 2.85 millimeter. Likewise, a portion of the insulating conductor encasement layer334embedding the conductor on a side opposite to the first side, in particular the first part334.1, may have a thickness in a range between 0.25 millimeter and 1.5 millimeter, in particular between 0.25 millimeter and 0.75 millimeter. The flux concentrator layer337may have a layer thickness in range between 0.25 millimeter and 5.5 millimeter, in particular between 0.25 millimeter and 1.75 millimeter.

As shown inFIG.17, it is also possible that the composite cable432does not comprise a support layer, but only a shield layer437and an insulating conductor encasement layer434in which the conductor433is embedded. Alternatively, as shown inFIG.18, it is also possible that the composite cable532only comprises a flux concentrator layer537and an insulating conductor encasement layer534in which the conductor533is embedded, but no support layer. In this configuration, the

As shown inFIG.19the composite cable632may also comprise a cross-section other than a substantially rectangular cross-section as shown inFIG.1-18. In the present embodiment, the composite cable632has an arc-shaped cross-section. The cable632is also a multi-layer composite cable comprising a shield layer or a flux concentrator layer637and an insulating conductor encasement layer634in which a substantially arc-shaped conductor633is embedded. With regard to the arc-shaped cross-section, the width dimension of the composite is measured along the first side638or along the second side639or along a midline between the first side538and the second side639which is parallel to the first side638and the second side539. Likewise, the thickness dimension may be measured in the radial direction along an axis normal to the first side638and the second side639.

FIG.20shows another embodiment of a multi-layer composite cable732which is a combination of the composite cable according toFIGS.11and14. The multi-layer composite cables732comprises a support layer736, an insulating conductor encasement layer734on top of the support layer736in which a conductor733is embedded, a flux concentrator layer737on top of the insulating conductor encasement layer734and a shield layer770arranged on top of the flux concentrator layer737opposite to the support layer736. The shield layer770may be, for example, a metallic coating on top of the flux concentrator layer737.

As shown onFIG.21, it is also possible to omit the support layer, like inFIG.17andFIG.18. Accordingly,FIG.21shows yet another embodiment of a multi-layer composite cable832which is a combination of the composite cable according toFIGS.17and18. The multi-layer composite cables832comprises a conductor833embedded in an insulating conductor encasement layer834, a flux concentrator layer837on top of the insulating conductor encasement layer834and a shield layer870arranged on top of the flux concentrator layer837.

InFIG.14-16,FIG.18andFIG.20-21, the respective insulating conductor encasement layer334,535,734,834preferably does not comprise any flux concentrator material due to the presence of the respective additional flux concentrator layer337,537,737837. However, it is also possible that the respective insulating conductor encasement layer334,535,734,834comprises a flux concentrator material in addition to the respective flux concentrator layer337,537,737837.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term “about”. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A±5 percent of A.