Patent Description:
It is known to employ different types of heaters in aerosol-generating articles for generating an aerosol. Typically, resistance heaters are employed for heating an aerosol-forming substrate such as an e-liquid. It is also known to provide "heat not burn" devices utilizing resistance heaters, which generate an inhalable aerosol by heating but not burning an aerosol-forming substrate containing tobacco.

Induction heaters offer advantages and have been proposed in the above devices. Induction heaters are for example described in <CIT>. In induction heaters, an induction coil is arranged around a component made from a conductive material. The component may be denoted as a heating element or susceptor. A high-frequency AC current is passed through the induction coil. As a result, an alternating magnetic field is created within the induction coil. The alternating magnetic field penetrates the heating element thereby creating eddy currents within the heating element. These currents lead to a heating of the heating element. In addition to heat generated by eddy currents, the alternating magnetic field may also cause the susceptor to heat due to the hysteresis mechanism. Some susceptors may even be of a nature that no, or almost no, eddy currents will take place. In such susceptors substantially all the heat generation is due to hysteresis mechanisms. Most common susceptors are of such a kind, where heat is generated by both mechanisms. A more elaborate description of the processes and responsible for generating heat in a susceptor, when penetrated by an alternating magnetic field may be found in <CIT>. Inductive heaters facilitate rapid heating which is beneficial for generating an aerosol during the operation of the aerosol-generating device.

<CIT> discloses an apparatus configured to heat smokable material, comprising a conical induction coil and a conical susceptor element with an internal cavity for receiving a consumable. The conical susceptor element tapers from the mouth end towards the opposite distal end of the apparatus.

It would be desirable to have an aerosol-generating device with an induction heater which can be heated in a controlled manner and which is easy to clean.

According to a first aspect of the invention there is provided an aerosol-generating device according to claim <NUM>, which comprises a housing having a chamber configured to receive at least a portion of an aerosol-generating article. In an aspect which is not covered by the claims, the chamber preferably comprises at least one heating element the heating element being a solid, elongate heating element extending into the chamber in a longitudinal direction of the chamber and configured to penetrate the aerosol-generating article received in the chamber. The heating element preferably has a conical shape and is tapered at its free end. The device comprises an induction coil disposed around at least a portion of the chamber and having a conical shape. The device further comprises a power supply and a controller connected to the induction coil and configured to provide an alternating electric current to the induction coil such that, in use, the inductor coil generates a fluctuating magnetic field for heating a heating element located in the chamber.

By providing a conical shaped induction coil, the heating characteristics of the heating element can be controlled. In this regard, the distance between the induction coil and the heating element influences the heat generation. A smaller distance between the induction coil and the heating element leads to a higher temperature of the heating element. By providing a conical coil, a heat gradient is generated in the heating element during operation of the induction heater. Preferably, the diameter of the induction coil increases from a proximal end of the chamber. Then, the temperature of the heating element is highest at the tip of the heating element.

The chamber comprises at least one heating element. The heating element may be integrally connected with the aerosol-generating device. Alternatively, the heating element may be part of the aerosol-generating article. For example, the heating element may be provided as electrically conductive particles or filaments in the article.

Aerosol-forming substrate containing tobacco may be provided in the form of an aerosol-generating article. The aerosol-generating article may be provided as a consumable such as a tobacco stick. In the following, the aerosol-generating article will be denoted as a consumable. These consumables may have an elongate rod-like shape. A consumable is typically pushed into the chamber of the device at the proximal end of the device. This end is the mouth end of the chamber into which the consumable is inserted. In the chamber, the heating element of the induction heater is configured to penetrate the consumable. Also, the heating element may be comprised in the consumable itself. After use, the consumable is removed and replaced by a new consumable.

In an aspect which is not covered by the claims, the heating element may be a solid, elongate heating element, extending into the chamber in a longitudinal direction of the chamber, configured to penetrate an aerosol-generating article received in the chamber. The heating element and coil may have a predefined length. The heating element may have the same length as the coil. The heating element may have the shape of a pin or blade. The heating element may be solid while the coil may have a helical shape such that the heating element can be arranged within the coil. The coil may have a frustoconical shape. The coil may be provided as a helical wound coil with the shape of a conical shaped helical spring. The coil may comprise contact elements such that an AC current can flow through the coil from the power supply. The AC current supplied to the induction coil is preferably a high frequency AC current. For the purpose of this application, the term "high frequency" is to be understood to denote a frequency ranging from about <NUM> Megahertz (MHz) to about <NUM> Megahertz (MHz) (including the range of <NUM> to <NUM>), in particular from about <NUM> Megahertz (MHz) to about <NUM> (including the range of <NUM> to <NUM>), and even more particularly from about <NUM> Megahertz (MHz) to about <NUM> Megahertz (MHz) (including the range of <NUM> to <NUM>). No direct or electrical connection needs to be established between the coil and the heating element, since the magnetic field generated by the coil penetrates the heating element and thereby heats the heating element by the mechanisms explained above. These mechanisms are eddy currents and hysteresis losses, which are converted into heat energy. The coil as well as the heating element may be made from a conductive material such as metal. The heating element and the coil may have a circular, elliptical or polygonal shaped cross-section. The shape of the heating element may be utilized to change the shape of a consumable during insertion of the consumable into the chamber. Providing a coil with a conical shape means that the sides of the conical shaped coil are inclined with respect to the longitudinal axis of the coil. When referring to the heating element, the coil and the chamber, the term 'longitudinal' refers to the direction in which the aerosol-generating article is inserted into the chamber and the term 'transverse' refers to a direction perpendicular to the direction in which the aerosol-generating article is inserted into the chamber.

The heating element may also have a conical shape. The heating element and the induction coil may have a corresponding shape such that the heating element can be arranged within the coil. A corresponding conical shape further means that the outer shape of the heating element and the shape encompassed by the coil both resemble a cone. The outer shapes of the heating element and the coil may be straight or slightly curved. By providing a coil and heating element with a corresponding conical shape, the heating properties of the heating element can be controlled. Also, by providing a conical shaped heating element, the cleaning properties of the heating element may be enhanced. In this regard, upon removing the consumable, residues of aerosol-forming substrate may stick to the heating element and impair the functionality of the heating element. Such residues may affect subsequent aerosol generation and are thus unwanted. By providing a conical shaped heating element, pushing a consumable over the heating element is simplified and less force is required to do so since the substrate of the consumable can be penetrated more easily. In addition, provision of a conical shaped heating element may reduce the amount of loose tobacco left behind in the device upon removal of the consumable, due to the reduced friction between the conical shaped heating element and the tobacco substrate. Also, manually cleaning the heating element may be easier due to the fact that the base of the heating element can be reached easier.

The heating element and the coil may have the same longitudinal axis such that the heating element is arranged surrounded by the coil in a central position. The angle between the longitudinal axis and the sides of the heating element seen from the proximal end of the device is denoted as apex angle of the heating element. Similarly, the angle between the longitudinal axis and the sides of the coil is denoted as apex angle of the coil. Configuring the heating element and the coil such that the distance between the two perpendicular to the surface of the heating element is essentially the same means that the apex angle of the two is essentially the same. Varying the distance between the heating element and the coil means that the apex angle of the heating element is different from the apex angle of the coil. Both the heating element and the induction coil may have a positive apex angle such that the heating element and the coil have a corresponding conical shape and the same orientation with respect to the conical shape.

The apex angle of the heating element may be essentially the same as the apex angle of the induction coil. In this way, homogeneous eddy currents may be generated throughout the heating element such that the heating element may be heated to a constant temperature.

Also, the apex angles of the induction coil and the heating element may be different to facilitate a heating gradient in the heating element during operation of the induction heater. By changing the apex angle of the heating element and the coil, the heating characteristics of the heating element can be controlled. In this case, the eddy currents created in the heating element and hysteresis effects may vary from the tip to the base of the heating element.

If it is desired that the tip of the heating element is heated to a higher temperature than the base of the heating element, the apex angle of the heating element is chosen smaller than the apex angle of the induction coil. In other words, the distance between the heating element and the coil may be chosen to be smaller at the tip of the heating element and larger at the base of the heating element, which means in a direction transverse to the longitudinal direction at the tip of the heating element. A tip of the heating element with a higher temperature may be preferred to heat substrate deep within the consumable and away from the tip of the consumable. The substrate inside the consumable may benefit from increased heating since it may be more tightly packed and denser, and may also be less dry since exposed to less ambient air.

The apex angle of the heating element may also be chosen to be larger than the apex angle of the coil. Consequently, the distance between the heating element may be chosen to be larger at the tip of the heating element than at the base of the heating element, which means in a direction transverse to the longitudinal direction at the base of the heating element. As a consequence, the tip of the heating element is heated to a temperature which is lower than the temperature to which the base of the heating element is heated. Heating the tip to a lower temperature than the base of the heating element may be beneficial in that the tip of an inserted consumable is in this case heated less and therefore may dry out less. This may reduce the amount of residues left behind in the device as the depleted consumable is removed from the device.

The chamber may have the shape of a slot or cavity corresponding to the shape of a consumable. The heating element may have an elongate shape such to penetrate the consumable. The heating energy emitted by the heating element during operation of the induction heater may be evenly distributed into the substrate of the consumable.

The induction coil of the induction heater may be arranged around the heating element within the housing. In this way, the coil may be protected from contamination for example by aerosol-forming substrate. The housing which constitutes the confinement for the coil may be made from material not susceptible to being heated, when penetrated by an alternating magnetic field. For example, the housing may be made from a non-conductive material such that no eddy currents are generated in the housing, and which is also not heatable through hysteresis mechanisms. In other words, the housing may be made from a non-susceptor material, for example a non-conductive, non-susceptor material. The whole housing of the device may be made from a non-conductive material. Alternatively, the section of the housing adjacent to the induction coil may be made from a non-conductive material.

The heating element may have a tapered free end. The free end is also denoted as tip of the heating element. By means of the tapered tip, the insertion of the consumable may be facilitated and the consumable may not be damaged during insertion. A tapered tip refers to a small section adjacent to the tip of the heating element. Contrarily, a conical shape refers to a substantial length of the element adjacent from the tapered tip of the element to the base of the element. A conical shape may be present if at least <NUM> percent, at least <NUM> percent or at least <NUM> percent of the length of the element resembles a cone. A conical shape may be present if the element resembles a cone over the whole length.

At least one air inlet may be provided at the side of the housing such that air can be drawn through the air inlet and emitted adjacent to the heating element. Alternatively, at least one air inlet is provided at the chamber of the housing such that air can be drawn through the air inlet next to an inserted consumable and emitted adjacent to the heating element. The air inlet may be formed as a groove in the chamber such that the consumable may be firmly held in the chamber or the diameter of the chamber may be larger than the diameter of a consumable. Air which is drawn into the device by the puff of a user may be drawn through the consumable adjacent to the heating element, and a heating action of the heating element may create an aerosol which is then inhaled by a user.

The chamber may resemble the shape of the consumable. The chamber may aid in holding the consumable over or inside of the heating element. The chamber may have a diameter which corresponds to the diameter of a consumable or be slightly smaller.

The heating element may comprise multiple heating elements. In all embodiments, a single heating element or multiple heating elements may be employed. Different sections of the heating element may be independently heatable by providing multiple heating elements. Multiple independently controllable induction coils may be provided for heating the multiple heating elements. One induction coil may be assigned to one heating element and AC current may be directed through one coil at a time to heat the respective heating element. The induction coils may be provided with separate contacting terminals for separately contacting the coils with the power supply. The different heating elements may be heated to different temperatures. For example, different materials with different electrical resistances may be employed for the different heating elements. The coils may be made from different materials with different electrical resistances. If multiple coils are employed, AC current of different strength may be directed through the different coils. Different pitches may be employed in the different coils. The pitch of the coil denotes the spacial distance between individual windings of the coil. These different configurations of the induction coil or coils may be utilized to control the generation of the magnetic field and thereby the heating of the heating element.

As described above, in an aspect which is not covered by the claims, the heating element may have an elongate cylindrical, preferably solid, shape such a consumable can be easily penetrated. According to the present invention, the heating element is a hollow heating element comprising an internal cavity, configured to receive an aerosol-generating article received in the chamber in the internal cavity. By means of the hollow shape, a consumable may thus be pushed inside of the heating element. The hollow heating element has a slightly curved surface to facilitate insertion of the consumable. Thus, the heating element has a conical shape with a slightly curved outer surface. The consumable may in this case be sandwiched in the internal cavity of the hollow heating element such that the consumable is held inside of the heating element by a press fit. The heat transferred from the heating element into the substrate of the consumable may be optimized, since the substrate in the consumable may be compressed and the distance between the heating element and the substrate may be minimized.

Since the heating element is hollow, the consumable may be pushed into the internal cavity of the heating element. The shape of the consumable may change during insertion due to the cross section of the hollow heating element. In this way, the heating of the aerosol-forming substrate in the consumable may be further optimized. For example, an elliptical cross-section of the heating element may be utilized to flatten the aerosol-forming substrate during insertion of the consumable.

The hollow heating element has a subsequently decreasing diameter seen from the proximal end of the device. Multiple hollow heating elements may have a successively decreasing diameter. The decreasing diameter may facilitate the insertion of the consumable and the consumable may be held securely within the device. The heating element may have the largest diameter at the tip which is firstly contacted by the consumable upon insertion of the consumable into the internal cavity of the heating element and the smallest diameter at the base of the heating element.

The controller may comprise a microprocessor, which may be a programmable microprocessor. The controller may comprise further electronic components. The controller may be configured to regulate a supply of electric power to the induction heater. Electric power may be supplied to the induction heater continuously following activation of the device or may be supplied intermittently, such as on a puff-by-puff basis. The power may be supplied to the induction heater in the form of pulses of electrical current.

The power supply may be a battery. As an alternative, the power supply may be another form of charge storage device such as a capacitor. The power supply may require recharging and may have a capacity that allows for the storage of enough energy for one or more puffs; for example, the power supply may have sufficient capacity to allow for the continuous generation of aerosol for a period of around six minutes or for a period that is a multiple of six minutes. In another example, the power supply may have sufficient capacity to allow for a predetermined number of puffs or discrete activations of the induction heater.

The aerosol-forming substrate may comprise homogenised tobacco material. The aerosol-forming substrate may comprise an aerosol-former. The aerosol-forming substrate preferably comprises homogenised tobacco material, an aerosol-former and water. Providing homogenised tobacco material may improve aerosol generation, the nicotine content and the flavour profile of the aerosol generated during heating of the aerosol-generating article. Specifically, the process of making homogenised tobacco involves grinding tobacco leaf, which more effectively enables the release of nicotine and flavours upon heating.

The induction heater may be triggered by a puff detection system. Alternatively, the induction heater may be triggered by pressing an on-off button, held for the duration of the user's puff.

The puff detection system may be provided as a sensor, which may be configured as an airflow sensor and may measure the airflow rate. The airflow rate is a parameter characterizing the amount of air that is drawn through the airflow path of the aerosol-generating device per time by the user. The initiation of the puff may be detected by the airflow sensor when the airflow exceeds a predetermined threshold. Preferably, initiation may also be detected upon a user activating a button.

The sensor may also be configured as a pressure sensor to measure the pressure of the air inside the aerosol-generating device which is drawn through the airflow path of the device by the user during a puff.

An aerosol-generating device as described above and a consumable may be an electrically operated smoking system. Preferably, the aerosol-generating system is portable. The aerosol-generating system may have a size comparable to a conventional cigar or cigarette. The smoking system may have a total length between approximately <NUM> millimetres and approximately <NUM> millimetres. The smoking system may have an external diameter between approximately <NUM> millimetres and approximately <NUM> millimetres.

The invention also relates to an aerosol-generating system comprising an aerosol-generating device as described above and an aerosol-generating article having an aerosol-generating substrate and configured for use with the aerosol-generating device.

<FIG> shows a conventional induction heater <NUM> with an elongate heating element <NUM> that is arranged within an induction coil <NUM>. The elongate heating element <NUM> has a tapered tip. Apart thereof, the elongate heating element <NUM> as well as the induction coil <NUM> have a constant diameter along the longitudinal length of the elongate heating element <NUM> and the induction coil <NUM>, respectively.

<FIG> shows the conventional induction heater <NUM> used in an aerosol-generating device <NUM>. The aerosol-generating device <NUM> comprises a housing <NUM>. The induction coil <NUM> is arranged within the housing <NUM>. The housing <NUM> also comprises a chamber <NUM> at a proximal end in which a consumable can be inserted. In the chamber <NUM>, the heating element <NUM> of the conventional induction heater <NUM> is arranged such that the heating element <NUM> can penetrate the consumable. In the housing <NUM> of the aerosol-generating device <NUM>, a battery <NUM> is arranged as well as a controller <NUM> for controlling the supply of electrical power from the battery <NUM> to the conventional induction heater <NUM>.

<FIG> shows an induction heater <NUM> which is not covered by the claims. The induction heater <NUM> comprises a conical shaped heating element <NUM> which is surrounded by a conical shaped induction coil <NUM>. Only the induction coil <NUM> may have a conical shape while the heating element <NUM> may not have a conical shape. The conical shaped heating element <NUM> has a tapered tip to facilitate the insertion of a consumable over the conical shaped heating element <NUM>. The conical shaped heating element <NUM> has a conical shape from the tip of the conical shaped heating element <NUM> to the base of the conical shaped heating element <NUM>.

The conical shaped induction coil <NUM> surrounds the conical shaped heating element <NUM> such that the distance perpendicular to the side surface of the conical shaped heating element <NUM> from the conical shaped heating element <NUM> to the conical shaped induction coil <NUM> remains essentially the same from the end of the tip of the conical shaped heating element <NUM> to the base of the conical shaped heating element <NUM>. Consequently, the conical shape of the induction coil <NUM> corresponds to the conical shape of the heating element <NUM>. In <FIG>, the longitudinal axis L of the heating element <NUM> as well as the induction coil <NUM> is shown. The apex angle α of the induction coil <NUM> is depicted, which is the angle between the longitudinal axis L and the shape of the outer sides of the induction coil <NUM>. The apex angle β is shown which is the angle between the longitudinal axis L and the outer surface of the heating element <NUM>. In the embodiment shown in <FIG>, the apex angle α is essentially the same as the apex angle β.

<FIG> shows in <FIG> the induction heater <NUM> used in an aerosol-generating device <NUM>. The aerosol-generating device <NUM> comprises a housing <NUM> encompassing a battery <NUM> and a controller <NUM>. Also, a chamber <NUM> at a proximal end is provided in the housing in which a consumable <NUM> can be placed. The induction heater <NUM> is placed near the chamber <NUM>. In more detail, the conical shaped heating element <NUM> is arranged in the chamber <NUM> such that a consumable <NUM> can be pushed easily over the conical shaped heating element <NUM> due to less friction occurring while pushing the consumable over the conical shaped side surface of the conical shaped heating element <NUM>. The conical shaped induction coil <NUM> of the induction heater <NUM> is arranged protected within the housing <NUM> around the conical shaped heating element <NUM>. In this way, only the conical shaped heating element <NUM> is accessible from the outside without opening the housing <NUM>. The conical shaped heating element <NUM> can be cleaned without interfering with the further components of the aerosol-generating device <NUM>.

In <FIG>, the consumable <NUM> comprising aerosol-forming substrate is shown before being inserted into the chamber <NUM> of the aerosol-generating device <NUM>. The consumable <NUM> is plugged into the chamber <NUM> by pushing the consumable <NUM> over the tip of the conical shaped heating element <NUM> until the consumable <NUM> reaches the base of the conical shaped heating element <NUM>. In <FIG>, the consumable <NUM> is fully pushed into the chamber <NUM> of the aerosol-generating device <NUM>.

<FIG> shows two embodiments of air inlets for the aerosol-generating device <NUM>. In <FIG>, an air inlet <NUM> is shown which is provided at a side surface of the aerosol-generating device <NUM>. The air inlet <NUM> allows ambient air to be drawn through the aerosol-generating device <NUM> and being expelled through the consumable <NUM>. In this way, the length of the air flow path within the device <NUM>, from the air inlet to the heating element may be minimized.

In Fig. 5c, a different configuration of an air inlet <NUM> is depicted. In this embodiment, ambient air can enter into the aerosol-generating device <NUM> next to the consumable <NUM> through the chamber <NUM>. The air inlet <NUM> is realized by a groove in the chamber <NUM>. Thus, no air inlets are necessary at the side surface of the device <NUM> such that the overall construction of the device <NUM> is simplified and it stability is increased.

<FIG> shows the heating element of the induction heater <NUM> being provided as a conical shaped heating element <NUM>, according to the invention.

The heating element <NUM> is hollow and has an elliptical cross-section. In <FIG>, the conical shaped elliptical heating element <NUM> is depicted. This heating element <NUM> comprises multiple heating elements <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. The heating elements <NUM> to <NUM> can be separately heated. The heating elements <NUM> to <NUM> can be made from different materials. Individual inductions coils may be provided around each of the heating elements <NUM> to <NUM> to facilitate an individual heating action. The heating elements <NUM> to <NUM> have a conical shape such that the diameter decreases from the first heating element <NUM> to the last heating element <NUM>.

In <FIG> a single heating element <NUM> is shown. In <FIG> the conical shaped elliptical heating element <NUM> is shown arranged along the side surface of the chamber <NUM> of an aerosol-generating device <NUM>. The conical shaped elliptical heating element <NUM> may be arranged inside of the chamber <NUM> of the aerosol-generating device <NUM> as a separate element. Alternatively, the heating element <NUM> may be configured as an integral part of the chamber <NUM> to form the side surface of the chamber <NUM>. The conical shaped elliptical heating element <NUM> is formed such that a low insertion force for pushing a consumable <NUM> in an internal cavity of the conical shaped elliptical heating element <NUM> reshapes the cross-section of the consumable <NUM> to a predominantly elliptical cross-section. An elliptical cross-section of the consumable <NUM> may facilitate an optimized heat transfer from the conical shaped elliptical heating element <NUM> to the consumable <NUM>, as the thickness of the consumable <NUM> is reduced.

<FIG> shows the embodiment depicted in <FIG>, wherein a consumable <NUM> has been pushed inside of the internal cavity of the conical shaped elliptical heating element <NUM>. An induction coil <NUM> is arranged protected within the housing <NUM> of the aerosol-generating device <NUM> and surrounds the conical shaped elliptical heating element <NUM>.

Claim 1:
An aerosol-generating device, comprising:
a housing having a chamber configured to receive at least a portion of an aerosol-generating article, wherein the chamber comprises at least one heating element,
an induction coil disposed around at least a portion of the chamber and having a conical shape;
a power supply and a controller connected to the induction coil and configured to provide an alternating electric current to the induction coil such that, in use, the induction coil generates a fluctuating magnetic field for heating the heating element located in the chamber, wherein the heating element is a hollow heating element comprising an internal cavity, wherein the heating element is configured to receive the aerosol-generating article received in the chamber in the internal cavity, and
wherein the hollow heating element has a conical shape with a slightly curved outer surface to facilitate insertion of the aerosol-generating article, wherein the hollow heating element has a subsequently decreasing diameter seen from a mouth end of the device.