Technical Field

The present disclosure relates generally to an aerosol generating device, and more particularly to an aerosol generating device for heating an aerosol generating substrate to generate an aerosol for inhalation by a user. The present disclosure is particularly applicable to a portable (hand-held) aerosol generating device. Embodiments of the present disclosure also relate to an aerosol generating system comprising an aerosol generating device and a cartridge containing an aerosol generating liquid and/or to an aerosol generating system comprising an aerosol generating device and an aerosol generating article comprising a non-liquid aerosol generating substrate.

Technical Background

The popularity and use of reduced-risk or modified-risk devices (also known as aerosol generating devices or vapour generating devices or personal vaporizers) has grown rapidly in recent years as an alternative to the use of traditional tobacco products. These devices heat, rather than bum, an aerosol generating substrate to generate an inhalable aerosol and can use one of a number of different approaches to provide heat to the aerosol generating substrate which can be in liquid form, solid form, or a semi-liquid form.

One approach is to provide an aerosol generating device which employs a resistive heating system. In such a device, a resistive heating element is provided to heat the aerosol generating substrate and an aerosol is generated as the aerosol generating substrate is heated by heat transferred from the heating element.

Another approach is to provide an aerosol generating device which employs an induction heating system. In such a device, an induction coil is provided with the device and a susceptor is also provided. Electrical energy is supplied 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 generating substrate and an inhalable aerosol is thereby generated.

Whichever approach is used to heat the aerosol generating substrate, there is a need to transfer heat efficiently to the aerosol generating substrate and the present disclosure seeks to address this need.

Summary of the Disclosure

According to a first aspect of the present disclosure, there is provided an aerosol generating device for heating an aerosol generating substrate to generate an aerosol for inhalation, the aerosol generating device comprising: a heat pipe comprising: a liquid which is vaporisable to form a vapour; a first end arranged to be positioned away from the aerosol generating substrate; a second end; a heater positioned at the first end of the heat pipe for heating and vaporising the liquid; and at least one heat transfer surface positioned away from the first end of the heat pipe for transferring heat from the vapour to the aerosol generating substrate to thereby heat the aerosol generating substrate.

The aerosol generating device is adapted to heat the aerosol generating substrate, without burning the aerosol generating substrate, to volatise at least one component of the aerosol generating substrate 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 heat pipe is partially filled with a liquid. The liquid in the heat pipe (which acts as a working fluid) is heated and vaporised by the heater during use of the device. Thus, the liquid in the heat pipe evaporates to form a vapour as it absorbs heat from the heater, creating a vapour pressure difference between the first end and an opposite cooler end (e.g., the second end) or cooler section of the heat pipe where the heat transfer surface is positioned. This vapour pressure difference causes a transfer of vapour from the heated first end to the opposite cooler end (e.g., the second end) or cooler section of the heat pipe where the heat transfer surface is positioned. The heat is transferred from the vapour to the aerosol generating substrate via the heat transfer surface and as the vapour cools due to this heat transfer, it condenses back into a liquid. The liquid then flows back to the first end of the heat pipe so that it can again be heated by the heater.

The heat pipe acts as a thermal energy transfer component and provides an effective and highly efficient way to transfer heat from the heater positioned at the first end of the heat pipe to the heat transfer surface positioned away from the first end of the heat pipe and, thus, to the aerosol generating substrate.

Optional features will now be set out. These are applicable singly or in any combination with any aspect of the present disclosure.

At least the second end of the heat pipe may be arranged to be positioned adjacent to the aerosol generating substrate to position the at least one heat transfer surface adj acent to the aerosol generating substrate. With this arrangement, the heat transfer surface may be positioned at, or adjacent to, the second end of the heat pipe. Heat is transferred efficiently to the aerosol generating substrate by at least the second end of the heat pipe.

A portion of the heat pipe extending from a position between the first end and the second end of the heat pipe to a position at the second end of the heat pipe may be arranged to be positioned adjacent to the aerosol generating substrate to position the at least one heat transfer surface adjacent to the aerosol generating substrate. A larger heat transfer surface may be provided with this arrangement.

The heat pipe may comprise a heat transfer element positioned at the second end. The heat transfer surface may be at least partly defined by the heat transfer element. The heat transfer element provides for effective and efficient heat transfer from the second end of the heat pipe to the aerosol generating substrate. The heat transfer element can comprise a material with a high thermal conductivity to ensure that heat is transferred to the aerosol generating substrate in the most efficient manner.

The heat transfer element may include a plurality of openings. The openings may advantageously allow a vapour or aerosol generated due to heating of the aerosol generating substrate to pass through the heat transfer element and along an airflow channel (aerosol outlet channel) of the aerosol generating device.

The heater may comprise a resistive heating element. The heater may be attached to an outer surface of the heat pipe at the first end or may be embedded in a side wall of the heat pipe at the first end. With these arrangements, heat is transferred efficiently from the resistive heating element to the liquid (i. e. , working fluid) at the first end of the heat pipe to thereby heat and vaporise the liquid.

The heater may comprise an inductively heatable susceptor. The aerosol generating device may comprise an induction coil which may be arranged to generate an alternating electromagnetic field for inductively heating the inductively heatable susceptor. This arrangement provides a particularly convenient way to heat the liquid (i.e., working fluid) using induction heating.

The inductively heatable susceptor may be positioned inside the heat pipe at the first end. Thus, there is direct contact between the liquid (i.e., working fluid) ensuring that heat is transferred efficiently from the inductively heatable susceptor to the liquid. The inductively heatable susceptor may comprise an elongate susceptor element. The use of an elongate susceptor element may increase the surface area over which heat can be transferred from the inductively heatable susceptor to the liquid (i. e. , working fluid), thereby providing for improved heat transfer and more effective heating of the liquid. The elongate susceptor element may comprise a pin-shaped susceptor. The heat pipe may be substantially cylindrical and the pin-shaped susceptor may be positioned concentrically inside the substantially cylindrical heat pipe. The elongate susceptor element may comprise a substantially tubular susceptor. The substantially tubular susceptor may be positioned inside the substantially cylindrical heat pipe, for example in contact with an inner circumferential surface of the substantially cylindrical heat pipe. Other susceptor geometries could be adopted as will be understood by one of ordinary skill in the art.

The heat pipe may include a wick positioned inside the heat pipe to convey condensed liquid, held in the heat pipe, from the second end to the first end. The wick may comprise an inductively heatable susceptor material. Thus, the wick also acts as the inductively heatable susceptor and the construction of the heat pipe is thereby simplified.

The induction coil may comprise a Litz wire or a Litz cable. It will, however, be understood that other materials could be used. The induction coil may be substantially helical in shape and may extend around at least the first end of the heat pipe at which the inductively heatable susceptor is positioned.

The inductively heatable susceptor 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 susceptor may generate heat due to eddy currents and magnetic hysteresis losses resulting in a conversion of energy from electromagnetic to heat. 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 2.0T at the point of highest concentration.

The aerosol generating device may include a power source and circuitry which may be configured to operate at a high frequency. The power source and circuitry may be configured to operate at a frequency of between approximately 80 kHz and 500 kHz, possibly between approximately 150 kHz and 250 kHz, and possibly at approximately 200 kHz. 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.

The liquid in the heat pipe may have a boiling up to approximately 350°C. The liquid may have a boiling point up to approximately 300°C, possibly up to approximately 275°C, possibly up to approximately 250°C. The use of a liquid (i.e., working fluid) with a higher boiling point allows a higher operating temperature to be achieved, but this needs to be balanced with ensuring that the aerosol generating device does not become so hot that it is uncomfortable for a user to hold. The liquid (i.e., working fluid) may comprise water, naphthalene, phenol, iodine, toluene, aniline or any other working fluid in the required temperature range known to those skilled in the art. In embodiments in which an inductively heatable susceptor is positioned inside the heat pipe at the first end, the liquid is ideally selected so that it does not cause any degradation of the inductively heatable susceptor.

According to a second aspect of the present disclosure, there is provided an aerosol generating system comprising an aerosol generating device and a cartridge containing an aerosol generating liquid releasably connectable to the aerosol generating device, the aerosol generating device comprising: a heat pipe comprising: a liquid which is vaporisable to form a vapour; a first end arranged to be positioned away from the aerosol generating liquid; a second end arranged to be positioned adjacent to the aerosol generating liquid; a heater positioned at the first end of the heat pipe for heating and vaporising the liquid; and a heat transfer surface at the second end of the heat pipe, the heat transfer surface being positioned adjacent to the aerosol generating liquid for transferring heat from the vapour to the aerosol generating liquid to thereby heat the aerosol generating liquid.

The heat pipe acts as a thermal energy transfer component and provides an effective and highly efficient way to transfer heat from the heater positioned at the first end of the heat pipe, in the aerosol generating device, to the heat transfer surface positioned away from the first end of the heat pipe and, thus, to the aerosol generating liquid in the cartridge. The components of the heater are part of the aerosol generating device and can, thus, be reused with multiple cartridges.

The aerosol generating liquid may comprise polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. The aerosol generating liquid may contain one or more additives, such as a flavouring. The flavouring may include Ethylvanillin (vanilla), menthol, cherry, Isoamyl acetate (banana oil) or similar, for instance. The aerosol generating liquid may contain one or more active ingredients, for example the aerosol generating liquid may contain nicotine.

The cartridge may comprise a liquid store and may comprise a liquid transfer element which may be configured to convey aerosol generating liquid from the liquid store to the heat transfer surface. The liquid transfer element may comprise a capillary wick. Thus, a controlled amount of aerosol generating liquid can be heated at the heat transfer surface.

The heat pipe may comprise a heat transfer element which may be positioned at the second end of the heat pipe in contact with the liquid transfer element. The heat transfer surface may be at least partly defined by the heat transfer element. The heat transfer element provides for effective and efficient heat transfer from the second end of the heat pipe to the liquid transfer element and, thus, to the conveyed aerosol generating liquid. It may be beneficial with such an arrangement if the heat transfer element includes a plurality of openings. As discussed above, the openings may advantageously allow a vapour or aerosol generated due to heating of the aerosol generating liquid to pass through the heat transfer element and along an airflow channel (aerosol outlet channel) of the aerosol generating device.

According to a third aspect of the present disclosure, there is provided an aerosol generating system comprising an aerosol generating device and an aerosol generating article comprising a non-liquid aerosol generating substrate, the aerosol generating device comprising: a heat pipe comprising: a liquid which is vaporisable to form a vapour; a first end arranged to be positioned away from the non-liquid aerosol generating substrate; a second end; a heater positioned at the first end of the heat pipe for heating and vaporising the liquid; and at least one heat transfer surface positioned away from the first end of the heat pipe for transferring heat from the vapour to the non-liquid aerosol generating substrate to thereby heat the non-liquid aerosol generating substrate.

The heat pipe acts as a thermal energy transfer component and provides an effective and highly efficient way to transfer heat from the heater positioned at the first end of the heat pipe, in the aerosol generating device, to the heat transfer surface positioned away from the first end of the heat pipe and, thus, to the non-liquid aerosol generating substrate of the aerosol generating article. The components of the heater are part of the aerosol generating device and can, thus, be reused with multiple aerosol generating articles.

A portion of the heat pipe extending from a position between the first end and the second end of the heat pipe to a position at the second end of the heat pipe may be positioned in the non-liquid aerosol generating substrate to position the at least one heat transfer surface in the non-liquid aerosol generating substrate. A large heat transfer surface can be achieved with this arrangement, ensuring that there is contact over a large surface area between the heat pipe (specifically the heat transfer surface) and the non-liquid aerosol generating material. This ensures that the non-liquid aerosol generating material is heated efficiently and uniformly.

The aerosol generating device may include a heating chamber for receiving the non- liquid aerosol generating substrate. The heat pipe may extend into the heating chamber so that the at least one heat transfer surface is positioned in the heating chamber. The heat pipe can, thus, be arranged so that the heat transfer surface penetrates the non- liquid aerosol generating substrate when it is inserted into the heating chamber to provide for efficient and uniform heating of the non-liquid aerosol generating substrate.

The non-liquid aerosol generating substrate may comprise any type of solid or semisolid material. Example types of aerosol generating solids include powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut filler, porous material, foam material or sheets. The non-liquid aerosol generating substrate may comprise plant derived material and in particular, may comprise tobacco. It may advantageously comprise reconstituted tobacco, for example including tobacco and any one or more of cellulose fibres, tobacco stalk fibres and inorganic fillers such as CaCO3.

Consequently, the aerosol generating device may be referred to as a “heated tobacco device”, a “heat-not-bum tobacco device”, a “device for vaporising tobacco products”, a “T-vapour” device and the like, with this being interpreted as a device suitable for achieving these effects.

The non-liquid aerosol generating substrate may be circumscribed by a paper wrapper to form the aerosol generating article. The aerosol generating article may be formed substantially in the shape of a stick, and may broadly resemble a cigarette, having a tubular region with a non-liquid aerosol generating substrate arranged in a suitable manner. The aerosol generating article may include a filter segment, for example comprising cellulose acetate fibres, at a proximal end of the aerosol generating article. The filter segment may constitute a mouthpiece filter and may be in coaxial alignment with the non-liquid aerosol generating substrate. One or more vapour collection regions, cooling regions, and other structures may also be included in some designs. For example, the aerosol generating article may include at least one tubular segment upstream of the filter segment. The tubular segment may act as a vapour cooling region. The vapour cooling region may advantageously allow heated vapour generated by heating the non-liquid aerosol generating substrate to cool and condense to form an aerosol with suitable characteristics for inhalation by a user, for example through the filter segment.

The non-liquid aerosol generating substrate may comprise an aerosol-former. Examples of aerosol-formers include polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. Typically, the non-liquid aerosol generating substrate may comprise an aerosol-former content of between approximately 5% and approximately 50% on a dry weight basis. In some embodiments, the non-liquid aerosol generating substrate may comprise an aerosol-former content of between approximately 10% and approximately 20% on a dry weight basis, and possibly approximately 15% on a dry weight basis.

Upon being heated by heat transferred from the heat transfer surface of the heat pipe, the non-liquid aerosol generating substrate may release volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco flavouring.

Brief Description of the Drawings

Figure 1 is a diagrammatic cross-sectional view from the front of an aerosol generating system comprising a first example of an aerosol generating device and cartridge configured for releasable connection to the aerosol generating device;

Figures 2 and 3 are diagrammatic cross-sectional views respectively from the front and side of the aerosol generating system of Figure 1, showing the cartridge connected to the aerosol generating device; Figure 4 is a diagrammatic view along the line A-A in Figure 2;

Figure 5 is a diagrammatic cross-sectional view from the front of an aerosol generating system comprising a second example of an aerosol generating device and cartridge configured for releasable connection to the aerosol generating device;

Figures 6 and 7 are diagrammatic cross-sectional views respectively from the front and side of the aerosol generating system of Figure 5, showing the cartridge connected to the aerosol generating device;

Figures 8 and 9 are diagrammatic cross-sectional views respectively from the front and side of an aerosol generating system comprising a third example of an aerosol generating device and an aerosol generating article positioned in a heating chamber of the aerosol generating device; and

Figures 10 and 11 are diagrammatic cross-sectional views respectively from the front and side of an aerosol generating system comprising a fourth example of an aerosol generating device and an aerosol generating article positioned in a heating chamber of the aerosol generating device.

Detailed Description of Embodiments

Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

Referring initially to Figures 1 to 3, there is shown a first example of an aerosol generating device 10 and a cartridge 12 for use with the aerosol generating device 10. The cartridge 12 is releasably connectable to the aerosol generating device 10 by a releasable connection. The releasable connection can, for example, be a snap-fit connection or alternatively a magnetic connection, a threaded connection, or a bayonet connection. The aerosol generating device 10 and the cartridge 12 together form an aerosol generating system 1.

The cartridge 12 comprises a cartridge housing 14 having a proximal end 16 and a distal end 18. The proximal end 16 may constitute a mouthpiece end configured for being introduced directly into a user's mouth and may, therefore, also be designated as the mouth end 16. The cartridge 12 comprises a liquid store 20 for storing an aerosol generating liquid 21 and a vaporization chamber 22. The liquid store 20 may extend generally between the proximal (mouth) end 16 and the distal end 18 and may surround, and co-extend with, an airflow channel 24. The airflow channel 24 extends between the proximal (mouth) end 16 and the distal end 18 and has an outlet 24b at the proximal (mouth) end 16. The outlet 24b is intended to deliver an inhalable aerosol into the mouth of a user. The cartridge 12 also includes one or more air inlets 26 formed in the cartridge housing 14 to deliver air to the vaporization chamber 22.

The aerosol generating liquid 21 stored in the liquid store 20 may comprise an aerosolforming substance such as propylene glycol and/or glycerol and may contain other substances such as nicotine and acids. The aerosol generating liquid 21 may also comprise flavourings such as e.g. tobacco, menthol or fruit flavour.

The cartridge 12 comprises a liquid transfer element 28 positioned in the vaporization chamber 22. The liquid transfer element 28 is configured to convey aerosol generating liquid 21 from the liquid store 20 to the vaporization chamber 22 so that the conveyed aerosol generating liquid 21 can be heated and vaporized as will be described below. The liquid transfer element 28 comprises a capillary material, such as a bundle of fibres (e.g., cotton) or porous ceramic material, and may be substantially planar, e.g., in the form of a disc or rectangular sheet as shown in Figure 4 which extends in a transverse direction, i.e., a direction substantially perpendicular to a longitudinal axis of the cartridge 12. The liquid transfer element 28 is in fluid communication with the aerosol generating liquid 21 in the liquid store 20. Thus, aerosol generating liquid 21 can be absorbed from the liquid store 20 by the liquid transfer element 28 and conveyed into the vaporization chamber 22.

The aerosol generating device 10 has a proximal end 30 and a distal end 32, and comprises a power source and control circuitry (not shown) connected to a heater 34. The power source typically comprises one or more batteries which could, for example, be inductively rechargeable. The aerosol generating device 10 further comprises a thermal energy transfer component in the form of a heat pipe 36 which is positioned at the proximal end 30 of the aerosol generating device 10. The heat pipe 36 has a first end 38 at which the heater 34 is positioned, a second end 40 and a heat transfer surface 46.

The heater 34 comprises a resistive heating element typically in the form of a heater coil which extends helically around the heat pipe 36 at the first end 38. The resistive heating element can be attached to an outer surface 42 of the heat pipe 36 at the first end 38 or can be embedded in a side wall 44 of the heat pipe 36 at the first end 38. Either way, heat can be transferred efficiently, e.g., by conduction, from the resistive heating element to the liquid inside the heat pipe 36 at the first end 38.

The heat transfer surface 46 is positioned at the second end 40 of the heat pipe 36 and is at least partly defined by a heat transfer element 48 comprising a highly thermally conductive material. The heat transfer element 48, along with the second end 40 of the heat pipe 36, extends into the vaporization chamber 22 and contacts the liquid transfer element 28 as shown in Figures 2 to 4 when the cartridge 12 is connected to the proximal end 30 of the aerosol generating device 10.

The heat pipe 36 is partially filled with a liquid (e.g., water) which acts as the working fluid and which can be heated and vaporised by the heater 34 to form a vapour. The heat pipe 36 is a sealed pipe and, thus, the working fluid, both in its liquid and vapour form, is sealed or locked inside the heat pipe 36. The heat pipe 36 is, therefore, a sealed component of the aerosol generating device 10 from which the working fluid cannot escape.

During use of the aerosol generating system 1, the liquid at the first end 38 of the heat pipe 36 is heated and vaporised by heat transferred to the liquid from the heater 34. Thus, the liquid in the heat pipe 36 evaporates to form a vapour as it absorbs heat from the heater, creating a vapour pressure difference between the first end 38 and the opposite cooler second end 40 where the heat transfer surface 46, and more particularly the heat transfer element 48, is positioned. This vapour pressure difference causes a transfer of vapour from the heated first end 38 to the opposite cooler second end 40 of the heat pipe 36. At the second end 40 of the heat pipe 36, the heat is transferred from the vapour to the liquid transfer element 28 via the heat transfer surface 46 of the heat transfer element 48. As the vapour inside the heat pipe 36 cools due to this heat transfer, it condenses back into a liquid. The liquid then flows back to the first end 38 of the heat pipe 36 so that it can again be heated by the heater 34 in a continuous process.

The heat transferred from the vapour at the second end 40 of the heat pipe 36 to the liquid transfer element 28 via the heat transfer surface 46 of the heat transfer element 48 results in heating and vaporization of the aerosol generating liquid 21 absorbed by the liquid transfer element 28 from the liquid store 20 and conveyed to the vaporization chamber 22. This results in the generation of a vapour in the vaporization chamber 22. As best seen in Figure 4, the heat transfer element 48 comprises a plurality of openings 50 through which air can flow and the heat transfer element 48 may, for example, comprise a mesh. The vapour tends to form on a lower surface of the liquid transfer element 28 and is entrained in an airflow through the aerosol generating device 10. This airflow causes the vapour to pass through the liquid transfer element 28 to its upper surface and into the airflow channel 24 as shown by the arrows in Figure 2. As the vapour flows along the airflow channel 24, it cools and condenses to form an aerosol that is inhaled by a user through the outlet 24b at the proximal end 16 of the cartridge 12. The vaporization of the aerosol generating liquid 21 is facilitated by the addition of air from the surrounding environment through the one or more air inlets 26. The flow of air and/or vapour and/or aerosol through the cartridge 12, i.e. from the one or more air inlets 26, through the vaporization chamber 22, along the airflow channel 24, and out of the outlet 24b, is aided by negative pressure created by a user drawing air from the proximal (mouth) end 16.

After the aerosol generating liquid 21 in the liquid store 20 of the cartridge 12 has been depleted, the cartridge 12 can be disconnected from the aerosol generating device 10 and a replacement cartridge 12 can then be connected in its place, to allow further use of the aerosol generating system 1 in the manner described above.

Referring now to Figures 5 to 7, there is shown a second example of an aerosol generating device 60 and a cartridge 12 for use with the aerosol generating device 60. The aerosol generating device 60 and the cartridge 12 together form an aerosol generating system 2. The cartridge 12 is the same as that described above with reference to Figures 1 to 4. The aerosol generating device 60 is similar to the aerosol generating device 10 described above with reference to Figures 1 to 4 and corresponding components are identified using the same reference numerals.

The heater 34 comprises an induction coil 62 and an inductively heatable susceptor 64. The induction coil 62 is a helical coil which is positioned in a body 66 of the aerosol generating device 10 to extend around at least the first end 38 of the heat pipe 36. The inductively heatable susceptor 64 is positioned inside the heat pipe 36 at least at the first end 38, and in the illustrated example the inductively heatable susceptor 64 is an elongate susceptor which extends from the first end 38 towards the second end 40 of the heat pipe 36. In an alternative example not shown in the drawings, the heat pipe 36 can include a wick positioned inside the heat pipe 36 to convey condensed liquid held inside the heat pipe 36 from the second end 40 to the first end 38, the wick being formed of an inductively heatable susceptor material. In this case, the construction of the heat pipe 36 may be simplified because the wick also acts as the inductively heatable susceptor 64. Purely by way of example, the wick (and hence the inductively heatable susceptor 64) may comprise a copper mesh, a copper powder, a copper wire, or any combination of these.

The inductively heatable susceptor 64 is positioned adjacent to the induction coil 62, and more specifically within the coil envelope. In operation, and as will be understood by one of ordinary skill in the art, when the aerosol generating device 60 is activated, the inductively heatable susceptor 64 is inductively heated by the induction coil 62, and more specifically by the alternating electromagnetic field generated by the induction coil 64. More particularly, eddy currents and/or magnetic hysteresis losses are generated in the inductively heatable susceptor 64 causing it to heat up. The heat is transferred from inductively heatable susceptor 64 to the liquid at the first end 38 of the heat pipe 36, thereby heating and vaporising the liquid. The vapour is transferred from the heated first end 38 to the cooler second end 40 of the heat pipe 36 as described above in connection with Figures 1 to 4 due to the vapour pressure difference inside the heat pipe 36. This results in heating of the liquid transfer element 28, and hence vaporization of the aerosol generating liquid 21 as described above in connection with Figures 1 to 4 to generate an aerosol which can be inhaled by a user via the outlet 24b of the airflow channel 24.

Referring now to Figures 8 and 9, there is shown a third example of an aerosol generating device 70 and an aerosol generating article 72 for use with the aerosol generating device 70. The aerosol generating device 70 and the aerosol generating article 72 together form an aerosol generating system 3.

The aerosol generating device 70 comprises a heating chamber 74 having a substantially circular cross-section for receiving the aerosol generating article 72. The heating chamber 74 is formed in a body 75 of the aerosol generating device 70 and has a longitudinal axis defining a longitudinal direction. The heating chamber 74 is open towards the proximal end 30 of the aerosol generating device 70. In other words, the heating chamber 18 has an open first end 76 at the proximal end 30 of the aerosol generating device 70 and a closed second end 77.

The heating chamber 74 is arranged to receive a correspondingly shaped generally cylindrical or rod-shaped aerosol generating article 72. Typically, the aerosol generating article 72 comprises a pre-packaged aerosol generating substrate 78. The aerosol generating article 72 is a disposable and replaceable article (also known as a “consumable”). The aerosol generating substrate 78 comprises a solid or semi-solid material (i.e. a non-liquid material) and may comprise plant derived material, and in particular tobacco. The aerosol generating substrate 78 may also include an aerosolformer, such as glycerine or propylene glycol, to facilitate the generation of a vapour or aerosol when heated.

The aerosol generating article 72 has a proximal end 80 (or mouth end) and a distal end 82. The aerosol generating article 72 further comprises a mouthpiece segment 84 positioned downstream of the aerosol generating substrate 78. The aerosol generating substrate 78 and the mouthpiece segment 84 are arranged in coaxial alignment inside a wrapper 86 (e.g., a paper wrapper) to hold the components in position to form the rodshaped aerosol generating article 72.

The mouthpiece segment 84 can comprise one or more of the following components (not shown in detail) arranged sequentially and in co-axial alignment in a downstream direction, in other words from the distal end 82 towards the proximal (mouth) end 80 of the aerosol generating article 72: a cooling segment, a center hole segment and a filter segment. The cooling segment typically comprises a hollow paper tube having a thickness which is greater than the thickness of the wrapper 86. The center hole segment may comprise a cured mixture containing cellulose acetate fibres and a plasticizer, and functions to increase the strength of the mouthpiece segment 84. The filter segment typically comprises cellulose acetate fibres and acts as a mouthpiece filter. As heated vapour flows from the aerosol generating substrate 78 towards the proximal (mouth) end 80 of the aerosol generating article 72, the vapour cools and condenses as it passes through the cooling segment and the center hole segment to form an aerosol with suitable characteristics for inhalation by a user through the filter segment.

The aerosol generating device 70 comprises athermal energy transfer component in the form of a heat pipe 90. The heat pipe 90 is similar to the heat pipe 36 described above in connection with Figures 1 to 7 so the description will not be repeated. The heat pipe 90 is mounted on the body 75 of the aerosol generating device 70 and extends (or projects) from the device body 75 into the heating chamber 74 in the longitudinal direction. The heat pipe 90 is positioned centrally within the circular cross-section of the heating chamber 74. When an aerosol generating article 72 is positioned in the heating chamber as shown in Figures 8 and 9, the heat pipe 90 is inserted into the aerosol generating substrate 78 and, thus, acts like a heater blade or heater pin in a conventional aerosol generating device. To facilitate insertion of the heat pipe 90 into the aerosol generating substrate 78, the second end 40 of the heat pipe 90 can be tapered as shown in Figure 8. In this example, a substantial portion of the total length of the heat pipe 90 is positioned in the aerosol generating substrate 78, i.e., a portion extending from a position between the first end 38 and the second end 40 to a position at the second end 40 is positioned in the aerosol generating substrate 78. The heat pipe 90 includes a plurality of heat transfer surfaces 46 which extend along the portion of the heat pipe 90 that is positioned in the aerosol generating substrate 78. The heat transfer surfaces 46 are defined by a highly thermally conductive material and can, for example, comprise a plurality of concentric heat transfer surfaces 46 extending between the first end 38 and second end 40 of the heat pipe 90. The heat transfer surfaces 46 contact the aerosol generating substrate 78 and, thus, allow heat to be transferred efficiently and uniformly from the vapour inside the heat pipe 90 to the aerosol generating substrate 78.

During use of the aerosol generating system 3, the liquid at the first end 38 of the heat pipe 90 is heated and vaporised by heat transferred to the liquid from the heater 34. Thus, the liquid in the heat pipe 90 evaporates to form a vapour as it absorbs heat from the heater, creating a vapour pressure difference between the first end 38 and a cooler section, positioned in the aerosol generating substrate 78, where the heat transfer surfaces 46 are located. This vapour pressure difference causes a transfer of vapour from the heated first end 38 to the cooler section of the heat pipe 90. The heat is transferred from the vapour in the cooler section of the heat pipe 90 to the aerosol generating substrate 78 via the heat transfer surfaces 46. As the vapour inside the heat pipe 90 cools due to this heat transfer, it condenses back into a liquid. The liquid then flows back to the first end 38 of the heat pipe 90 so that it can again be heated by the heater 34 in a continuous process.

The heat transferred from the vapour to the aerosol generating substrate 78 via the heat transfer surfaces 46 of the heat pipe 90 results in heating of the aerosol generating substrate 78 and a vapour is thereby generated. The generated vapour cools and condenses to form an aerosol for inhalation by a user of the aerosol generating system 3 through the mouthpiece segment 84, and more particularly through a filter segment (mouthpiece filter). The vaporisation of the aerosol generating substrate 78 is facilitated by the addition of air from the surrounding environment through the open first end 76 of the heating chamber 74, the airflow being between the wrapper 86 of the aerosol generating article 72 and the inner surface of the heating chamber 74 when a user sucks on the filter segment (mouthpiece filter) of the aerosol generating article 72.

A user can continue to inhale aerosol all the time that the aerosol generating substrate 78 is able to continue to produce a vapour, e.g., all the time that the aerosol generating substrate 78 has vaporisable components left to vaporise into a suitable vapour. When the aerosol generating substrate 78 has been depleted and no longer generates an aerosol with acceptable qualities, the aerosol generating article 72 can be removed from the heating chamber 74 and replaced with another aerosol generating article 72.

Referring now to Figures 10 and 11, there is shown a fourth example of an aerosol generating device 100 and an aerosol generating article 72 for use with the aerosol generating device 100. The aerosol generating device 100 and the aerosol generating article 72 together form an aerosol generating system 4. The aerosol generating article 72 is the same as that described above with reference to Figures 8 and 9. The aerosol generating device 100 is similar to the aerosol generating device 70 described above with reference to Figures 8 and 9 and corresponding components are identified using the same reference numerals.

The heater 34 comprises an induction coil 62 and an inductively heatable susceptor 64. The induction coil 62 is a helical coil which is positioned in a body 75 of the aerosol generating device 100 to extend around at least the first end 38 of the heat pipe 90. The inductively heatable susceptor 64 is positioned inside the heat pipe 90 at least at the first end 38, and in the illustrated example the inductively heatable susceptor 64 is an elongate susceptor which extends from the first end 38 towards the second end 40 of the heat pipe 90. It should, however, be noted that the inductively heatable susceptor 64 does not extend into the portion of the heat pipe 90 where the heat transfer surfaces 46 are provided. In other words, the inductively heatable susceptor 64 and the heat transfer surfaces 46 do not overlap in the longitudinal direction.

The inductively heatable susceptor 64 is positioned adjacent to the induction coil 62, within the coil envelope. In operation, and as will be understood by one of ordinary skill in the art, when the aerosol generating device 100 is activated, the inductively heatable susceptor 64 is inductively heated by the induction coil 62, and more specifically by the alternating electromagnetic field generated by the induction coil 64. More particularly, eddy currents and/or magnetic hysteresis losses are generated in the inductively heatable susceptor 64 causing it to heat up. The heat is transferred from inductively heatable susceptor 64 to the liquid at the first end 38 of the heat pipe 90, thereby heating and vaporising the liquid. The vapour is transferred from the heated first end 38 to the cooler section of the heat pipe 90 where the heat transfer surfaces 46 are located as described above in connection with Figures 8 and 9, due to the vapour pressure difference inside the heat pipe 90. This results in heating of the aerosol generating substrate 78, and hence the generation of a vapour which cools and condenses to form an aerosol that is inhaled by a user through the mouthpiece segment 84, and more particularly through a filter segment (mouthpiece filter) of the aerosol generating article 72.

Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments.

Any combination of the above-described features in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.