Patent Description:
Devices which heat, rather than bum, an aerosol forming material to produce an aerosol for inhalation have become popular with consumers in recent years.

Such devices can use one of a number of different approaches to provide heat to the aerosol forming material. One such approach is to provide an aerosol generating device which employs an induction heating system and into which an aerosol generating article, comprising aerosol forming material, can be removably inserted by a user. In such a device, an induction coil is provided with the device and an induction heatable susceptor is also provided. Electrical energy is provided to the induction coil when a user activates the device which in turn generates an alternating electromagnetic field. The susceptor couples with the electromagnetic field and generates heat which is transferred, for example by conduction, to the aerosol forming material and an aerosol is generated as the aerosol forming material is heated. An example of an inductively-heated aerosol generating device is described in <CIT>, from which the preamble of claims <NUM> and <NUM> is derivable.

Embodiments of the present disclosure seek to provide an improved user experience in which the characteristics of the aerosol are optimised.

According to a first aspect of the present disclosure, there is provided an aerosol generating device for heating an aerosol generating article to generate an aerosol for inhalation by a user, the aerosol generating device comprising:.

The aerosol generating article comprises an aerosol forming material and the projecting element acts as an inductively heatable susceptor which heats the aerosol forming material, without burning the aerosol forming material, to volatise at least one component of the aerosol forming material and thereby generate an aerosol for inhalation by a user of the aerosol generating device.

In general terms, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour can be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms 'aerosol' and 'vapour' may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user.

The projecting element acts as a reusable susceptor and is a separate component to the aerosol generating article rather than being integrated into the aerosol generating article at the time of manufacture. The aerosol generating article is thus easier and cheaper to manufacture than an aerosol generating article which incorporates one or more induction heatable susceptors integrated into the aerosol generating article. The risk of contamination, e.g., metal contamination, of the aerosol forming material by the induction heatable susceptor during storage is also eliminated or at least reduced because the induction heatable susceptor is brought into contact with the aerosol forming material only at the point of use, when an aerosol generating article is positioned in the heating compartment of the aerosol generating device.

The projecting element may be elongate. By removably mounting the projecting element on the aerosol generating device, the projecting element can be easily removed and replaced if it becomes soiled or contaminated, for example with deposits of aerosol forming material following a period of use.

The projecting element may be removably mounted on the device body.

The aerosol generating device may include a connector for removably mounting the projecting element. The provision of a connector allows for easy removable mounting of the projecting element and may advantageously ensure an appropriate positional relationship between the projecting element and the induction coil.

The aerosol generating device may further comprise a mouthpiece which is removably mounted on the device body and the mouthpiece may include the projecting element. Thus, removal and replacement of the projecting element on the device body may be carried out by removing and replacing the mouthpiece. This is advantageous as both the mouthpiece and the projecting element are elements that should be periodically replaced with approximately the same periodicity and providing for them both to be replaced at the same time is convenient for the user.

The projecting element may be arranged in the heating compartment so that a longitudinal axis of the projecting element is substantially aligned with a longitudinal axis of the induction coil. This positional relationship ensures optimum coupling of the electromagnetic field generated by induction coil with the projecting element.

The controller may be configured to detect the mounting of a projecting element on the device body. The controller may be configured to indicate a timing change of the projecting element (that is to indicate that it is time to change the projecting element or to indicate the remaining "life" of the projecting element before it should optimally be changed, etc.). For example, the controller may be configured to detect a predetermined power level supplied to the induction coil and to indicate a timing change of the projecting element based on the detected power level. In particular, the device can monitor the total energy supplied to the induction coil over time since inserting a new susceptor (by integrating the power supplied to the coil over time) and can determine that after a predetermined amount of energy has been supplied to the coil it is time for the susceptor to be changed. A notification that the susceptor should be changed can be provided to the user via any suitable means - e.g. by a warning light flashing in a predetermined pattern, etc..

The controller may be configured to detect the mounting of a new projecting element on the aerosol generating device. The controller may be configured to indicate a timing change of the projecting element after detecting the mounting of a new projecting element on the aerosol generating device, for example based on the detected power level. Alternatively or in addition, the controller may be configured to cease power supply to the induction coil after detecting the mounting of a new projecting element on the aerosol generating device and based on the detected power level. This arrangement ensures that the projecting element, i.e. the reusable susceptor, is replaced at appropriate time intervals to ensure optimum heating of aerosol generating articles used with the aerosol generating device.

In an embodiment, the controller may be configured to detect the mounting of a new projecting element on the aerosol generating device, for example on the device body, by detecting a characteristic associated with the projecting element. The characteristic could be an identification characteristic and could comprise an identification signal, for example emitted by a RFID tag associated with the projecting element. Alternatively, the user could indicate that the projecting element has been replaced with a new projecting element, e.g. by performing a predetermined action such as a button press or a series of button presses, etc..

The controller may be configured to detect the placement of an aerosol generating article in the heating compartment.

The controller may be configured to detect the consumption of aerosol forming material by detecting at least one of the following:.

Additionally it should be noted that the techniques for determining that a projecting element should be changed could generally also be used for detecting the amount of consumption of aerosol forming material and vice versa as will be apparent to a person skilled in the art.

The aerosol generating device may include a sensor, for example an optical sensor, to enable the controller to detect the number of aerosol generating articles inserted into the heating compartment.

The aerosol generating device may include one or more sensors to detect the movement of the one or more component parts, such as the projecting element, a mouthpiece or a cover to allow access to the heating compartment, to enable the controller to detect the movement of the one or more components of the aerosol generating device.

The controller may be configured to detect the level of consumption of aerosol forming material and to indicate a timing change of the projecting element based on the detected consumption level and/or to cease power supply to the induction coil based on the detected consumption level. The controller may be configured to detect the level of consumption of aerosol forming material after detecting the mounting of a new projecting element on the aerosol generating device. The controller may be further configured to indicate a timing change of the projecting element based on the detected consumption level after detecting the mounting of a new projecting element on the aerosol generating device and/or to cease power supply to the induction coil based on the detected consumption level after detecting the mounting of a new projecting element on the aerosol generating device and until the mounting of a new projecting element on the aerosol generating device is detected. Again, this arrangement ensures that the projecting element, i.e. the reusable susceptor, is replaced at appropriate time intervals to ensure optimum heating of aerosol generating articles used with the aerosol generating device.

The projecting element may be part of the device body.

The projecting element may include an air passage in communication with one or both of an air inlet and an air outlet of the aerosol generating device. This arrangement may advantageously improve the delivery of aerosol from the aerosol generating article.

The aerosol generating device may comprise a plurality of said projecting elements which may project into the heating compartment from opposite ends of the heating compartment. At least one of said plurality of projecting elements may be arranged at a first end of the heating compartment, for example on the mouthpiece or cover, and at least one of said plurality of projecting elements may be arranged at a second end of the heating compartment, for example on the device body. The provision of a plurality of projecting elements may advantageously improve the delivery of aerosol from the aerosol generating article even if the aerosol generating article is completely sealed before it is pierced by the projecting elements.

According to a second aspect of the present disclosure, there is provided an aerosol generating system for generating an aerosol for inhalation by a user, the aerosol generating system comprising:.

Because the sealing member is broken at the point of use, for example due to piercing by the projecting element, a hermetically sealed aerosol generating article can be used without the need for additional packaging.

The aerosol generating article may comprise aerosol forming material which may define a cavity in which the projecting element is positioned. The cavity may comprise a hole in the aerosol forming material. The cavity may be positioned in a centre region of the aerosol generating article. With this arrangement, the cavity defines a space for receiving the projecting element. Thus, aerosol forming material is not substantially displaced by the projecting element during positioning of the aerosol generating article in the heating compartment and this may provide more uniform heating of the aerosol forming material.

The projecting element may be spaced from the aerosol forming material. By providing a gap between the surface of the projecting element and the aerosol forming material, delivery of aerosol from the aerosol generating article may be advantageously improved.

According to a third aspect of the present disclosure, there is provided a kit of parts comprising:.

As above, the element is adapted for removable mounting in an aerosol generating device, for example an aerosol generating device comprising an induction coil for inductively heating at least part of the element. The element may be adapted for removable mounting in a heating compartment of an aerosol generating device. The element does not form part of the aerosol generating device and can be removably mounted in the aerosol generating device with an aerosol generating article after being positioned next to the aerosol forming material of an aerosol generating article.

The element may be a projecting element and may be elongate. The element may be adapted for use individually with the plurality of aerosol generating articles by being positioned in the aerosol forming material.

The element acts as an induction heatable susceptor which is intended for use with all of the aerosol generating articles in the kit. The aerosol generating articles are, thus, easier and cheaper to manufacture than aerosol generating articles which incorporate one or more induction heatable susceptors integrated into each of the aerosol generating articles at the point of manufacture. The risk of contamination, e.g., metal contamination, of the aerosol forming material by the induction heatable susceptor during storage is also eliminated or at least reduced because the induction heatable susceptor is brought into contact with the aerosol forming material only at the point of use, when the element acting as the induction heatable susceptor is positioned next to the aerosol forming material.

The aerosol generating article may be elongate and may be substantially cylindrical. The cylindrical shape of the aerosol generating article with its circular cross-section may advantageously facilitate insertion of the aerosol generating article into the heating compartment of an aerosol generating device, in particular when the induction coil is a helical induction coil having a circular cross-section. The ability of the heating compartment to receive a substantially cylindrical aerosol generating article to be heated is advantageous as, often, vaporisable aerosol forming substances, and tobacco products in particular, are packaged and sold in a cylindrical form. It is also advantageous because induction heatable susceptors are also conveniently formed to have a cylindrical shape (e.g. forming a hollow, tubular cylinder) so as to provide efficient heating when inductively excited by the induction coil, and by forming the aerosol generating article also as a cylinder relatively uniform heating of the article can be conveniently achieved which provides good aerosol formation.

The induction coil may be arranged to operate in use with a fluctuating electromagnetic field having a magnetic flux density of between approximately 20mT and approximately <NUM>. 0T at the point of highest concentration.

The aerosol generating device may include a power source. The power source and the controller may be configured to operate at a high frequency. The power source and controller may be configured to operate at a frequency of between approximately <NUM> and <NUM>, possibly between approximately <NUM> and <NUM>, and possibly at approximately <NUM>. The power source and circuitry could be configured to operate at a higher frequency, for example in the MHz range, depending on the type of inductively heatable susceptor that is used.

Whilst the induction coil may comprise any suitable material, typically the induction coil may comprise a Litz wire or a Litz cable.

Whilst the aerosol generating device may take any shape and form, it may be arranged to take substantially the form of the induction coil, to reduce excess material use. As noted above, the induction coil may be substantially helical in shape and may have a circular cross-section, thus the aerosol generating device may be substantially cylindrical and may have a substantially circular cross-section.

The circular cross-section of a helical induction coil facilitates the insertion of an aerosol generating article into the heating compartment and ensures uniform heating of the aerosol generating article. The resulting shape of the aerosol generating device is also comfortable for the user to hold.

The at least part of the projecting element that is inductively heatable may comprise one or more, but not limited, of aluminium, iron, nickel, stainless steel and alloys thereof, e.g. Nickel Chromium or Nickel Copper. With the application of an electromagnetic field in its vicinity, the at least part of the projecting element that is inductively heatable may generate heat due to eddy currents and/or magnetic hysteresis losses resulting in a conversion of energy from electromagnetic to heat.

The aerosol forming material may be any type of solid or semi-solid material. Example types of aerosol forming solids include powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut filler, porous material, foam material or sheets. The aerosol forming material may comprise plant derived material and in particular, may comprise tobacco.

The aerosol forming material may comprise an aerosol-former. Examples of aerosol-formers include polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. Typically, the aerosol forming material may comprise an aerosol-former content of between approximately <NUM>% and approximately <NUM>% on a dry weight basis. In some embodiments, the aerosol forming material may comprise an aerosol-former content of approximately <NUM>% on a dry weight basis.

Upon heating, the aerosol forming material may release volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco flavouring.

Referring initially to <FIG>, there is shown diagrammatically a first embodiment of an aerosol generating system <NUM>. The aerosol generating system <NUM> comprises an aerosol generating device <NUM> and an aerosol generating article <NUM>. The aerosol generating device <NUM> has a proximal end <NUM> and a distal end <NUM> and comprises a device body <NUM> which includes a power source <NUM> and a controller <NUM> which may be configured to operate at high frequency. The power source <NUM> typically comprises one or more batteries which could, for example, be inductively rechargeable.

The aerosol generating device <NUM> comprises a generally cylindrical heating compartment <NUM> at the proximal end <NUM> which is arranged to receive a correspondingly shaped generally cylindrical aerosol generating article <NUM> containing an aerosol forming material <NUM>. The aerosol generating article <NUM> comprises a non-metallic cylindrical outer shell 24a, an air-permeable layer or membrane 24b at the distal end and an impermeable sealing layer 24c at the proximal end. The aerosol generating article <NUM> is a disposable article <NUM> which may, for example, contain tobacco as the aerosol forming material <NUM>. The aerosol generating device <NUM> includes an air inlet <NUM> to deliver air to the heating compartment <NUM>.

The aerosol generating device <NUM> comprises a helical induction coil <NUM> which has a circular cross-section and which extends around the cylindrical heating compartment <NUM>. The induction coil <NUM> can be energised by the power source <NUM> and controller <NUM>. The controller <NUM> includes, amongst other electronic components, an inverter which is arranged to convert a direct current from the power source <NUM> into an alternating high-frequency current for the induction coil <NUM>.

The aerosol generating device <NUM> comprises a mouthpiece <NUM> which is removably mountable on the device body <NUM> at the proximal end <NUM> and through which a user may inhale vapour generated during use of the device <NUM>. The mouthpiece <NUM>, which is shown diagrammatically in <FIG>, includes one or more air outlets <NUM> which allow aerosol generated during use of the device <NUM> to flow from the heating compartment <NUM> and into the mouth of a user.

The mouthpiece <NUM> includes a projecting element <NUM> which projects into the heating compartment <NUM> when the mouthpiece <NUM> is mounted on the device body <NUM> as shown schematically in <FIG>. The projecting element <NUM> is elongate and has a tapered end which is suitable for breaking the sealing layer 24c of the aerosol generating article <NUM>. More particularly, the tapered end is adapted to pierce the sealing layer 24c of an aerosol generating article <NUM> that has been positioned in the heating compartment <NUM> thereby allowing air to flow from the heating compartment <NUM> through the air outlets <NUM> in the mouthpiece <NUM>. When the mouthpiece <NUM> is mounted on the device body <NUM> at the proximal end <NUM> of the device <NUM>, the projecting element <NUM> penetrates and extends into the aerosol forming material <NUM> such that the surface of the projecting element <NUM> contacts the aerosol forming material <NUM> adjacent to it.

At least part of the projecting element <NUM>, and possibly the whole of the projecting element <NUM>, comprises an inductively heatable susceptor material. Thus, when the induction coil <NUM> is energised by the alternating high-frequency current, an alternating and time-varying electromagnetic field is produced. This couples with the inductively heatable susceptor material of the projecting element <NUM> and generates eddy currents and/or hysteresis losses in the inductively heatable susceptor material causing it to heat up. The heat is then transferred from the inductively heatable susceptor material to the aerosol forming material <NUM>, for example by conduction, radiation and convection.

The heat transferred from the inductively heatable susceptor material of the projecting element <NUM> to the aerosol forming material <NUM> causes it to heat up and thereby produce an aerosol. The aerosolisation of the aerosol forming material <NUM> is facilitated by the addition of air from the surrounding environment through the air inlet <NUM> which flows through the air-permeable layer 24b and through the aerosol forming material <NUM>. The aerosol generated by heating the aerosol forming material <NUM> then exits the heating compartment <NUM>, through the opening in the sealing layer 24c created by piercing with the projecting element <NUM> and through the air outlets <NUM>, and is inhaled by a user of the device <NUM> through the mouthpiece <NUM>. It will be understood that the flow of air through the heating compartment <NUM>, i.e. from the air inlet <NUM>, through the heating compartment <NUM> and out of the air outlets <NUM> in the mouthpiece <NUM>, can be aided by negative pressure created by a user drawing air from the outlet side of the device <NUM> using the mouthpiece <NUM>.

In some embodiments, the controller <NUM> can be configured to detect the mounting of a new projecting element <NUM> in the heating compartment <NUM>, for example by detecting an identification characteristic associated with the projecting element <NUM>. After detecting the mounting of anew projecting element <NUM>, the controller <NUM> can be further configured to detect the power level supplied to the induction coil <NUM> and to indicate a timing change of the projecting element <NUM> based on the detected power level and/or to cease power supply to the induction coil <NUM> based on the detected power level until the controller <NUM> detects that another new projecting element <NUM> has been positioned in the heating compartment <NUM>.

In some embodiments, the controller <NUM> can be configured to detect the consumption of aerosol forming material <NUM> by detecting one or more of: the number of puffs; the length of the total puff period; the number of aerosol generating articles <NUM> inserted into the heating compartment <NUM>, for example using an optical sensor (not shown); and the movement of one or more components of the aerosol generating device <NUM>, for example the movement of the mouthpiece <NUM>, that are required to allow the placement of an aerosol generating article <NUM> in the heating compartment <NUM>.

In some embodiments, the controller <NUM> can advantageously be configured to detect the level of consumption of aerosol forming material <NUM> after detecting the positioning of a new projecting element <NUM> in the heating compartment <NUM>, and can be configured to indicate a timing change of the projecting element <NUM> based on the detected consumption level and/or to cease power supply to the induction coil <NUM> based on the detected consumption level until the controller <NUM> detects that another new projecting element <NUM> has been positioned in the heating compartment <NUM>.

Referring now to <FIG>, there is shown diagrammatically a second embodiment of an aerosol generating system <NUM> which is similar to the aerosol generating system <NUM> illustrated in <FIG> and in which corresponding elements are designated using the same reference numerals.

In addition to the projecting element <NUM> that extends in use from the mouthpiece <NUM> into the heating compartment <NUM> at its proximal end, the aerosol generating device <NUM> includes a plurality of further projecting elements <NUM> which project into the heating compartment <NUM> at its distal end. At least part, and possibly the whole, of one or more of the further projecting elements <NUM> comprise an inductively heatable susceptor material. In some embodiments, at least part, and possibly the whole, of all of the further projecting elements <NUM> comprise an inductively heatable susceptor material.

The aerosol generating article <NUM> of this second embodiment comprises a non-metallic cylindrical outer shell 124a, an impermeable sealing layer 124b at the distal end and an impermeable sealing layer 124c at the proximal end. The aerosol generating article <NUM> is, thus, fully sealed by the impermeable sealing layers 124b, 124c and the non-metallic outer shell 124a prior to being positioned in the heating compartment <NUM>. When the mouthpiece <NUM> is mounted onto the device body <NUM> at the proximal end <NUM> of the device <NUM>, the projecting element <NUM> pierces the sealing layer 124c of an aerosol generating article <NUM> that has been positioned in the heating compartment <NUM> thereby allowing air to flow from the heating compartment <NUM> through the air outlets <NUM> in the mouthpiece <NUM>. In addition, a force is applied to the aerosol generating article <NUM> during mounting of the mouthpiece <NUM> (e.g. from a downward facing abutment surface of the mouthpiece <NUM> in which the projecting element is embedded) and this causes the further projecting elements <NUM> to pierce the sealing layer 124b, thereby permitting air to flow into the aerosol generating article <NUM> and through the aerosol forming material <NUM>.

When the induction coil <NUM> is energised by the alternating high-frequency current, an alternating and time-varying electromagnetic field is produced. This couples with the inductively heatable susceptor material of the projecting element <NUM> and the further projecting elements <NUM> and generates eddy currents and/or hysteresis losses in the inductively heatable susceptor material causing it to heat up. The heat is then transferred from the inductively heatable susceptor material to the aerosol forming material <NUM>, for example by conduction, radiation and convection.

The heat transferred from the inductively heatable susceptor material of the projecting element <NUM> and the further projecting elements <NUM> to the aerosol forming material <NUM> causes it to heat up and thereby produce an aerosol. The aerosolisation of the aerosol forming material <NUM> is facilitated by the addition of air from the surrounding environment through the air inlet <NUM> which flows through the pierced sealing layer 124b into the aerosol generating article <NUM> and through the aerosol forming material <NUM>. The aerosol generated by heating the aerosol forming material <NUM> then exits the heating compartment <NUM>, through the opening in the sealing layer 124c created by piercing with the projecting element <NUM> and through the air outlets <NUM>, and is inhaled by a user of the device <NUM> through the mouthpiece <NUM> in the manner described above.

Referring now to <FIG>, there is shown diagrammatically a third embodiment of an aerosol generating system <NUM> which is similar to the aerosol generating system <NUM> illustrated in <FIG> and in which corresponding elements are designated using the same reference numerals.

The aerosol generating system <NUM> comprises an aerosol generating device <NUM> having an integrally formed mouthpiece <NUM> at the proximal end <NUM> of the device <NUM> and in which the heating compartment <NUM> is located at the distal end <NUM> of the device <NUM>. A cover <NUM> for the heating compartment <NUM> is removably mountable on the device body <NUM> at the distal end <NUM>. The cover <NUM> includes a projecting element <NUM> which projects into the heating compartment <NUM> when the cover <NUM> is mounted on the device body <NUM> as shown schematically in <FIG>. The projecting element <NUM> is the same as the projecting element <NUM> described above in connection with <FIG>. The cover <NUM> may also include one or more air inlets (not shown) to allow air to flow into the heating compartment <NUM>.

The aerosol generating article <NUM> is also as described above in connection with <FIG> but is shown in an inverted orientation in <FIG>. The aerosol generating article <NUM> thus comprises a non-metallic cylindrical outer shell 24a, an air-permeable layer or membrane 24b at the proximal end and an impermeable sealing layer 24c at the distal end. It will be understood that when the cover <NUM> is mounted on the device body <NUM> at the distal end <NUM> of the device <NUM>, the projecting element <NUM> penetrates and extends into the aerosol forming material <NUM> such that the surface of the projecting element <NUM> contacts the aerosol forming material <NUM>.

The operation of the aerosol generating system <NUM> is similar to the operation of the aerosol generating system <NUM> described above in connection with <FIG>. Thus, when the induction coil <NUM> is energised by the alternating high-frequency current, an alternating and time-varying electromagnetic field is produced. This couples with the inductively heatable susceptor material of the projecting element <NUM> and generates eddy currents and/or hysteresis losses in the inductively heatable susceptor material causing it to heat up. The heat is then transferred from the inductively heatable susceptor material to the aerosol forming material <NUM>, for example by conduction, radiation and convection.

The heat transferred from the inductively heatable susceptor material of the projecting element <NUM> to the aerosol forming material <NUM> causes it to heat up and thereby produce an aerosol. The aerosolisation of the aerosol forming material <NUM> is facilitated by the addition of air from the surrounding environment which flows through the pierced sealing layer 24c and through the aerosol forming material <NUM>. The aerosol generated by heating the aerosol forming material <NUM> then exits the heating compartment <NUM> through the air-permeable layer 24b, along passage <NUM> and through the air outlet <NUM> where it is inhaled by a user of the device <NUM> through the mouthpiece <NUM>. It will be understood that the flow of air through the heating compartment <NUM> can be aided by negative pressure created by a user drawing air from the outlet side of the device <NUM> using the mouthpiece <NUM>.

Referring now to <FIG>, there is shown diagrammatically a fourth embodiment of an aerosol generating system <NUM> which is similar to the aerosol generating system <NUM> illustrated in <FIG> and in which corresponding elements are designated using the same reference numerals.

In addition to the projecting element <NUM> that extends in use from the cover <NUM> into the heating compartment <NUM> at its distal end, the aerosol generating device <NUM> includes a plurality of further projecting elements <NUM> which project into the heating compartment <NUM> at its proximal end. The further projecting elements <NUM> are as described above in connection with <FIG>.

The aerosol generating article <NUM> is also as described above in connection with <FIG> but is shown in an inverted orientation in <FIG>. The aerosol generating article <NUM> comprises a non-metallic cylindrical outer shell 124a, an impermeable sealing layer 124b at the proximal end and an impermeable sealing layer 124c at the distal end. The aerosol generating article <NUM> is, thus, fully sealed by the impermeable sealing layers 124b, 124c and the non-metallic shell 124a prior to being positioned in the heating compartment <NUM>. When the cover <NUM> is mounted onto the device body <NUM> at the distal end <NUM> of the device <NUM>, the projecting element <NUM> pierces the sealing layer 124c of an aerosol generating article <NUM> that has been positioned in the heating compartment <NUM>, thereby allowing air to flow into the heating compartment <NUM>. In addition, a force is applied to the aerosol generating article <NUM> during mounting of the cover <NUM> and this causes the further projecting elements <NUM> to pierce the sealing layer 124b, thereby permitting air to flow out of the heating compartment <NUM> and along the passage <NUM>.

The operation of the aerosol generating system <NUM> is similar to the operation of the aerosol generating system <NUM> described above. Thus, when the induction coil <NUM> is energised by the alternating high-frequency current, an alternating and time-varying electromagnetic field is produced. This couples with the inductively heatable susceptor material of the projecting element <NUM> and the further projecting elements <NUM> and generates eddy currents and/or hysteresis losses in the inductively heatable susceptor material causing it to heat up. The heat is then transferred from the inductively heatable susceptor material to the aerosol forming material <NUM>, for example by conduction, radiation and convection.

The heat transferred from the inductively heatable susceptor material of the projecting element <NUM> and the further projecting elements <NUM> to the aerosol forming material <NUM> causes it to heat up and thereby produce an aerosol. The aerosolisation of the aerosol forming material <NUM> is facilitated by the addition of air from the surrounding environment which flows through the pierced sealing layer 124c and through the aerosol forming material <NUM>. The aerosol generated by heating the aerosol forming material <NUM> then exits the heating compartment <NUM> through the pierced sealing layer 124b, along passage <NUM> and through the air outlet <NUM> where it is inhaled by a user of the device <NUM> through the mouthpiece <NUM>. It will be understood that the flow of air through the heating compartment <NUM> can be aided by negative pressure created by a user drawing air from the outlet side of the device <NUM> using the mouthpiece <NUM>.

Referring now to <FIG>, there is shown diagrammatically part of a fifth embodiment of an aerosol generating system <NUM> which is similar to the aerosol generating system <NUM> illustrated in <FIG> and in which corresponding elements are designated using the same reference numerals.

The aerosol generating system <NUM> comprises a generally annular cylindrical aerosol generating article <NUM> comprising a cylindrical body of aerosol forming material <NUM> which is formed to include a cavity <NUM>. The cylindrical annular aerosol generating article <NUM> is shown in <FIG> positioned in the heating compartment <NUM> at the proximal end <NUM> of an aerosol generating device. The aerosol generating device is similar to the aerosol generating device <NUM> described above with reference to <FIG> and comprises a plurality of air inlets 22a which direct air into the heating compartment <NUM> as shown in <FIG>.

The aerosol generating device comprises a mouthpiece <NUM> with a projecting element <NUM> that is positioned in the cavity <NUM> when the mouthpiece <NUM> is mounted on the device body <NUM> at the proximal end <NUM> of the aerosol generating device. In the illustrated embodiment, the outer diameter of the projecting element <NUM> is smaller than the inner diameter of the body of aerosol forming material <NUM> so that the circumferentially and axially extending outer surface of the projecting element <NUM> is spaced from (an internal or inner cylindrical surface of) the aerosol forming material <NUM> without contacting it, as clearly shown in <FIG>. In other embodiments (not illustrated), the outer diameter of the projecting element <NUM> could be substantially equal to the inner diameter of the body of aerosol forming material <NUM> so that the outer surface of the projecting element <NUM> contacts the adjacent inner surface of the aerosol forming material <NUM> when the projecting element <NUM> is positioned in the cavity <NUM>.

The projecting element <NUM> comprises a plurality of radially extending air passages <NUM> and a longitudinal air passage <NUM>. The passages <NUM>, <NUM> promote the flow of air through the air inlets 22a into and through the heating compartment <NUM> of the aerosol generating device and promote the flow of aerosol generated by heating the aerosol forming material <NUM> into air passages <NUM> formed in the mouthpiece <NUM> and through the air outlet <NUM> as shown schematically by the arrows in <FIG>.

Referring now to <FIG>, there is shown a kit of parts <NUM> for aerosol generation which comprises a plurality of aerosol generating articles <NUM>, for example twenty aerosol generating articles <NUM>. Each aerosol generating article <NUM> comprises a body of aerosol forming material <NUM> surrounded by a non-metallic cylindrical outer shell 62a, for example a paper wrapper. Each aerosol generating article <NUM> further comprises an air-permeable plug <NUM>, for example comprising cellulose acetate fibres, at an axial end thereof.

The kit <NUM> further includes an element <NUM> which in the illustrated embodiment is elongate. At least part of the elongate element <NUM>, and possibly the whole of the elongate element <NUM>, comprises an inductively heatable susceptor material as described above with reference to <FIG>. The elongate element <NUM> extends from a metallic mesh <NUM> through which air can flow; an air-permeable plug <NUM>, for example comprising cellulose acetate fibres, is positioned adjacent to the mesh <NUM>.

The elongate element <NUM> and its associated metallic mesh <NUM> and air-permeable plug <NUM> is adapted for use individually with the plurality of aerosol generating articles <NUM> in the kit <NUM>. As best seen in <FIG>, the elongate element <NUM> is positioned by a user adjacent to the aerosol forming material <NUM> of an individual aerosol generating article <NUM> by pushing the elongate element <NUM> into the body of aerosol forming material <NUM> until it is fully inserted into the body. The assembled aerosol generating article <NUM> and elongate element <NUM> can then be inserted into the heating compartment <NUM> of the aerosol generating device <NUM> as denoted by the arrow in <FIG>. Once inserted in the heating compartment <NUM>, the aerosol generating device <NUM> is operated in the same manner described above with reference to <FIG>. Thus, when the induction coil <NUM> is energised by the alternating high-frequency current, an alternating and time-varying electromagnetic field is produced. This couples with the inductively heatable susceptor material of the elongate element <NUM> and generates eddy currents and/or hysteresis losses in the inductively heatable susceptor material causing it to heat up. The heat is then transferred from the inductively heatable susceptor material to the body of aerosol forming material <NUM>, for example by conduction, radiation and convection.

The heat transferred from the inductively heatable susceptor material of the elongate element <NUM> to the aerosol forming material <NUM> causes it to heat up and thereby produce an aerosol. The aerosolisation of the aerosol forming material <NUM> is facilitated by the addition of air from the surrounding environment through the air inlet <NUM> which flows through the air-permeable plug <NUM> and the metallic mesh <NUM> and through the aerosol forming material <NUM>. The aerosol generated by heating the aerosol forming material <NUM> then exits through the air-permeable plug <NUM> which acts as a mouthpiece. It will be understood that the flow of air through the aerosol forming material <NUM> can be aided by negative pressure created by a user drawing air through the air-permeable plug <NUM>.

After use of an individual one of the aerosol generating articles <NUM> with the aerosol generating device <NUM>, the aerosol generating article <NUM> is removed from the device <NUM> by a user. Thereafter, the elongate element <NUM>, along with its associated metallic mesh <NUM> and air-permeable plug <NUM>, is separated from the aerosol generating article <NUM> and is used again in the same manner with the remaining aerosol generating articles <NUM> in the kit <NUM>. Once all of the aerosol generating articles <NUM> in the kit have been used, the elongate element <NUM>, along with its associated metallic mesh <NUM> and air-permeable plug <NUM>, is discarded and a new kit <NUM> is used.

In some embodiments, the controller <NUM> may be configured to detect the number of aerosol generating articles <NUM> inserted into the heating compartment <NUM> and may be configured to cease power supply to the induction coil <NUM> until a replacement elongate element <NUM> is inserted into the heating compartment <NUM>. For example, if the kit <NUM> contains twenty aerosol generating articles <NUM>, the controller <NUM> could be configured to cease power supply to the induction coil <NUM> after the twenty aerosol generating articles <NUM>, assembled with the same elongate element <NUM>, have been inserted into the heating compartment <NUM>.

The controller <NUM> could be configured to detect the use of a new elongate element <NUM>, associated with a new kit <NUM>, for example by detecting an identification characteristic associated with the elongate element <NUM>. After detecting the use of a new elongate element <NUM>, the controller <NUM> could be configured to detect a predetermined power level supplied to the induction coil <NUM> and to indicate a timing change of the elongate element <NUM> based on the detected power level and/or could be configured to detect the number of aerosol generating articles <NUM> inserted into the heating compartment <NUM> and to cease power supply to the induction coil <NUM> after a predetermined number of aerosol generating articles <NUM> have been inserted into the heating compartment <NUM>.

Claim 1:
An aerosol generating device (<NUM>, <NUM>) for heating an aerosol generating article (<NUM>, <NUM>, <NUM>) to generate an aerosol for inhalation by a user, the aerosol generating device comprising:
an induction coil (<NUM>);
a heating compartment (<NUM>) arranged to receive an aerosol generating article; and
a projecting element (<NUM>, <NUM>, <NUM>) which projects into the heating compartment so that at least part of the projecting element is positioned inside an aerosol generating article received, in use, in the heating compartment;
wherein at least part of the projecting element is inductively heatable in the presence of a time varying electromagnetic field;
characterised in that:
the projecting element (<NUM>, <NUM>) is removably mounted on the aerosol generating device; and
the aerosol generating device further comprises a device body (<NUM>) including a controller (<NUM>) that is configured to detect the mounting of the projecting element (<NUM>, <NUM>) on the aerosol generating device.