Technical Field

The present disclosure relates generally to a cartridge for a vapour generating device configured to heat a vapour generating liquid to generate a vapour which cools and condenses to form an aerosol for inhalation by a user of the device.

Technical Background

The term vapour generating device (or more commonly electronic cigarette or e-cigarette) refers to a handheld electronic device that is intended to simulate the feeling or experience of smoking tobacco in a traditional cigarette. Electronic cigarettes work by causing a vapour generating liquid (or so called “e-liquid”) to be heated to generate a vapour that cools and condenses to form an aerosol which is then inhaled by the user.

Some vapour generating devices use induction heating to heat the vapor generating liquid. Such vapour generating devices employ an electromagnetic field generator such as an induction coil to generate an alternating electromagnetic field that couples with, and inductively heats, an inductively heatable susceptor. The vapour generating liquid can be transferred from a liquid store by a liquid transfer element, such as a wick, and is heated and vaporised by heat transferred from the inductively heatable susceptor, resulting in the generation of a vapour that cools and condenses to form an aerosol which is then inhaled by the user.

Whilst the use of induction heating in vapour generating devices is efficient, currently available inductively heated vapour generating devices can suffer from a number of drawbacks which the present disclosure seeks to address.

Summary of the Disclosure

According to a first aspect of the present disclosure, there is provided a cartridge for a vapour generating device, the cartridge comprising: a liquid store for containing a vapour generating liquid; and a vapour generating unit, the vapour generating unit comprising: a vaporisation device including a heating element comprising an inductively heatable susceptor; and a liquid transfer element arranged to hold and transfer vapour generating liquid from the liquid store to the vaporisation device by capillary action; wherein the inductively heatable susceptor is arranged in thermal proximity to the liquid transfer element to heat and vaporise the vapour generating liquid held and transferred to the vaporisation device by the liquid transfer element; wherein the inductively heatable susceptor surrounds the liquid transfer element and has an inner surface that contacts an outer surface of the liquid transfer element; wherein the inductively heatable susceptor has an inner diameter of from 3 mm to 10 mm, the liquid transfer element having an outer diameter corresponding to the inner diameter of the inductively heatable susceptor.

With this arrangement there is no gap between the outer surface of the liquid transfer element and the inner surface of the inductively heatable susceptor. Thus, heat can be readily conducted from the inductively heatable susceptor to the liquid transfer element thereby improving vapour generation and energy efficiency.

The larger the inner diameter of the inductively heatable susceptor, the greater the surface area which can be inductively heated to generate vapour, and thus the more vapour which can be potentially generated. However, since the outer diameter of the liquid transfer element is defined by the inner diameter of the inductively heatable susceptor, the volume of the liquid transfer element will also be increased by increasing the inner diameter of the inductively heatable susceptor. An increased amount of vapour generating liquid will thus be held and transferred to the vaporisation device by the liquid transfer element for heating by the inductively heatable susceptor. This may lead to an increased amount of time (and thus energy) required to heat the vapour generating liquid to generate vapour. An arrangement comprising an inductively heatable susceptor having an inner diameter of from 3 mm to 10 mm and a liquid transfer element having a corresponding outer diameter has surprisingly been found to provide an optimum balance between the quantity of vapour generated and the time (and thus energy) required to generate the vapour, thus improving performance.

The inductively heatable susceptor preferably may have an inner diameter of from 5 mm to 8 mm, or of from 5.5 mm to 7.5 mm, or most preferably may have an inner diameter of 7 mm. An inductively heatable susceptor having these inner diameter dimensions (and a liquid transfer element having a corresponding outer diameter) further optimises the balance between the quantity of vapour generated and the time (and thus energy) required to generate the vapour, thus further improving performance.

The inductively heatable susceptor may have an axial length of from 0.5 mm to 15 mm, or preferably may have an axial length of from 3 mm to 5 mm, or most preferably may have an axial length of 4 mm. An inductively heatable susceptor having these axial length dimensions may further optimise the balance between the quantity of vapour generated and the time (and thus energy) required to generate the vapour, thus further improving performance.

The inductively heatable susceptor may comprise a susceptor tube, which provides optimum performance thereby further improving vapour generation and energy efficiency.

Possibly, the liquid transfer element comprises at least two different materials, wherein a first of the materials is a porous ceramic; and wherein a second of the materials has a thermal conductivity and/or mechanical strength which is different from the porous ceramic. The second of the materials may comprise air pockets. Such arrangements can provide a required mechanical strength and/or interrupt the undesirable thermal bridge between the liquid store and the inductively heatable susceptor. In other examples, the liquid transfer element may comprise or may be formed of one material. The material may be configured to withstand temperatures of at least 400°C without any change of shape or material properties. The liquid transfer element may comprise porous ceramic, glass, high temperature plastics or high temperature foam, for instance neoprene foam.

The inductively heatable susceptor may be spaced apart from an induction coil by a distance of less than 4 mm, or preferably may be spaced apart from an induction coil by a distance of less than 2 mm, or most preferably may be spaced apart from an induction coil by a distance of less than 1 mm. Energy efficiency is improved as the distance separating the inductively heatable susceptor and the induction coil decreases. This helps to ensure that a strong electromagnetic coupling is achieved with the generated electromagnetic field.

Possibly, the cartridge comprises a cup defining an airflow guide, wherein the vapour generating unit is disposed in the interior of the cup, wherein air is flowable in use from the surrounding environment into the interior of the cup through one or more air inlets to flow over the inductively heatable susceptor. This arrangement improves airflow over the inductively heatable susceptor and directs airflow into a vaporisation chamber defined by the liquid transfer element, further improving vapour generation and energy efficiency.

The liquid transfer element may comprise a hollow core which may define a vaporisation chamber. The liquid transfer element may be toroidal and may be substantially tubular. The liquid transfer element may comprise a base. The base may comprise at least one indentation which engages with the cup, wherein the at least one indentation is configured such that an airflow path is defined for allowing air to flow from the interior of the cup into the vaporisation chamber. The base of the liquid transfer element may comprise a plurality of indentations. Accordingly, in use air flows both over the outside and the inside of the liquid transfer element.

According to a second aspect of the present disclosure, there is provided a vapour generating system comprising a vapour generating device and a cartridge according to any of the above paragraphs.

Brief Description of the Drawings

Figure 1 is a diagrammatic perspective view of a cartridge for use with a vapour generating device;

Figure 2a is a diagrammatic perspective view of a part of a cartridge;

Figure 2b is a diagrammatic perspective view of the part of Figure 2a showing an indication of airflow in use;

Figure 3 is a diagrammatic cross-sectional view of the part of Figure 2a and an induction coil, and showing an indication of airflow in use; and

Figure 4 is a diagrammatic view of a vapour generating system comprising a vapour generating device and a cartridge.

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, 2a, 2b and 3 there is shown a cartridge 10 according to the present disclosure. The cartridge 10 is configured to be used with a vapour generating device 100 as shown diagrammatically in Figure 4. The cartridge 10 and the vapour generating device 100 together form a vapour generating system 110. Accordingly, the present disclosure also provides a vapour generating system 110 comprising a vapour generating device 100 and a cartridge 10.

The vapour generating device 100 may be elongate and have a substantially cylindrical shape which resembles a cigarette or cigar. Other shapes are, however, entirely within the scope of the present disclosure.

The term vapour generating device 100 (or more commonly electronic cigarette or e-cigarette) refers to a handheld electronic device that is intended to simulate the feeling or experience of smoking tobacco in a traditional cigarette. Electronic cigarettes work by causing a vapour generating liquid to be heated to generate a vapour that cools and condenses to form an aerosol which is then inhaled by the user. Accordingly, using e-cigarettes is also sometimes referred to as “vaping”. Vapour generating liquid is sometimes referred to as e-liquid.

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 vapour generating liquid may comprise polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. The vapour generating liquid may contain nicotine. The vapour generating liquid may also comprise flavourings such as e.g., tobacco, menthol or fruit flavour.

The cartridge 10 comprises a housing 11 having a proximal end 15 and a distal end 17. The proximal end 15 constitutes a mouthpiece 44, i.e., a mouthpiece end, configured for being introduced directly into a user's mouth and may, therefore, also be designated as the mouth end. The mouthpiece 44 provides the ability for a user to easily inhale aerosol generated by the vapour generating device 100. The cartridge 10 comprises a liquid store 12 for containing, i.e., for holding or storing, a vapour generating liquid. Accordingly, the liquid store 12 is configured for containing therein a vapour generating liquid.

The liquid store 12 may extend generally between the proximal (mouth) end 15 and the distal end 17. The cartridge 10 comprises a vapour outlet channel 46. The vapour outlet channel 46 is fluidly connected to the mouthpiece 44. The liquid store 12 may surround, and coextend with, the vapour outlet channel 46.

As illustrated in Figure 4, in the illustrated example the vapour generating device 100 includes a controller 48. The vapour generating device 100 may include a user interface 50 for controlling the operation of the vapour generating device 100 via the controller 48 and/or for displaying information. In some examples, the user interface 48 may be comprised in a separate device such as a mobile device.

The controller 48 may be configured to detect the initiation of use of the vapour generating device 100 in response to a user input, such as a button press to activate the vapour generating device 100, or in response to a detected airflow through the vapour generating device 100. As will be understood by one of ordinary skill in the art, an airflow through the vapour generating device 100 is indicative of a user inhalation or ‘puff. The vapour generating device 100 may, for example, include a puff detector (not shown), such as an airflow sensor, to detect an airflow through the vapour generating device 100.

The controller 48 includes electronic circuitry 52. The vapour generating device 100 includes a power source 54, such as a battery. The power source 54 and the electronic circuitry 52 may be configured to operate at a high frequency. The power source 54 and the electronic circuitry 52 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 54 and the electronic circuitry 52 could be configured to operate at a higher frequency, for example in the MHz range, if required.

The cartridge 10 may be releasably connectable to the vapour generating device 100 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. Accordingly, after the vapour generating liquid in the liquid store 12 of the cartridge 10 has been depleted, the cartridge 10 can be disconnected from the vapour generating device 100 and a replacement cartridge 10 can then be connected in its place, to allow further use of the vapour generating device 100. The cartridge 10 may be disposable. Alternatively, in some examples the cartridge 10 may be re-filled with vapour generating liquid so that the cartridge 10 can be re-used.

The cartridge 10 comprises a vapour generating unit 13. The vapour generating unit 13 comprises a vaporisation device 14 and a liquid transfer element 20. The vaporisation device 14 includes a heating element 16, i.e., a heater 16, to produce vapour from the vapour generating liquid contained in the liquid store 12.

The liquid transfer element 20 is arranged to hold and transfer vapour generating liquid from the liquid store 12 to the vaporisation device 14 by capillary action. The liquid transfer element 20 is positioned outside the inner volume of the liquid store 12, and more particularly beneath the liquid store 12. An advantage of this arrangement is that it allows the delivery of liquid to the liquid transfer element 20 to be carefully controlled whilst minimising heat transfer from the liquid transfer element 20 to the vapour generating liquid in the liquid store 12.

The heating element 20 comprises an inductively heatable susceptor 18. The inductively heatable susceptor 18 is arranged coaxially with respect to a central longitudinal axis of the cartridge 10.

In the illustrated example, the inductively heatable susceptor 18 comprises a susceptor tube 19, which provides optimum performance. In other examples, the inductively heatable susceptor 18 may comprise a susceptor ring or susceptor rings. The susceptor rings may be spaced along the central longitudinal axis of the cartridge 10.

The inductively heatable susceptor 18 has a tube wall 21. The inductively heatable susceptor 18 is open-ended. The inductively heatable susceptor 18 is elongate and hollow. The inductively heatable susceptor 18 has a wrap-around structure. In the illustrated example, the inductively heatable susceptor 18 is substantially cylindrical. The substantially cylindrical inductively heatable susceptor 18 has a ring-shaped cross-section. In other examples, the inductively heatable susceptor 18 may be oval shaped or conical shaped. In some examples, for instance the example illustrated in Figure 1, openings 23 extend through the tube wall 21 of the inductively heatable susceptor 18. The openings 23 are apertures, through-holes, or perforations. Accordingly, the tube wall 21 comprises a plurality of openings 23. Vaporisation of the vapour generating liquid is facilitated by airflow through the openings 23. Improved vaporisation can allow for the design of smaller devices 100 with reduced power consumption. Furthermore, vapor is formed on the edges of the inductively heatable susceptor 18. Accordingly, by providing openings 23, there are more edges and therefore more vapor is generated in use.

In the illustrated example, the openings 23 are substantially circular shaped openings. In other examples, the openings 23 may have a different shape.

The openings 23 are distributed over the majority of the tube wall 21. The openings 23 are arranged in rows. Each row extends around the circumference of the inductively heatable susceptor 18. Accordingly, the openings 23 are arranged in circumferentially adjacent rows. The openings 23 in adjacent rows are staggered. Accordingly, the openings 23 in each row are axially offset from the openings 23 in circumferentially adjacent rows to provide a staggered arrangement of the openings 23. The openings 23 in each row are uniformly spaced apart. The rows are uniformly spaced apart.

An uninterrupted path is defined through the material of the inductively heatable susceptor 18 between respective adjacent rows of openings 23. Each uninterrupted path extends around the circumference of the inductively heatable susceptor 18. Accordingly, each uninterrupted path extends circumferentially. In the illustrated example, each uninterrupted path extends directly around the circumference of the inductively heatable susceptor 18.

In other examples, for instance the examples illustrated in Figures 2a, 2b and 3, the tube wall 21 does not comprise openings extending therethrough. In such examples, an uninterrupted path is defined through the material of the inductively heatable susceptor 18 around its circumference.

The inductively heatable susceptor 18 may have athickness up to 150 pm, preferably may have a thickness from 30 pm to 150 pm, more preferably may have athickness from 100 pm to 150 pm, or most preferably may have a thickness of 100 pm. An inductively heatable susceptor 18 having these thickness dimensions may be particularly suitable for being inductively heated during use of the cartridge 10 with a vapour generating device 100 and may also facilitate manufacture of the cartridge 10.

The inductively heatable susceptor 18 is arranged in thermal proximity to the liquid transfer element 20 to heat and vaporise the vapour generating liquid held and transferred to the vaporisation device 14 by the liquid transfer element 20.

With reference to Figure 3, in the illustrated example the vapour generating device 100 comprises an electromagnetic field generator 27 arranged to generate an alternating electromagnetic field for inductively heating the inductively heatable susceptor 18. The electromagnetic field generator 27 comprises an induction coil 28.

In the illustrated example, the induction coil 28 surrounds the inductively heatable susceptor 18 when the cartridge 10 is connected to the vapour generating device 100. By providing the induction coil 28 as an integral part of the vapour generating device 100, the manufacture and assembly of the cartridge 10 may be simplified. Thus, in the illustrated example the induction coil 28 belongs to the vapour generating device 100 and is brought into proximity with (e.g., to surround) the inductively heatable susceptor 18 when the cartridge 10 is connected to the vapour generating device 100, for instance, via a releasable connection.

In other examples, the cartridge 10 comprises an electromagnetic field generator 27. The electromagnetic field generator 27 comprises an induction coil 28. In such examples, the induction coil 28 is an integral part of, and belongs to, the cartridge 10 and surrounds the inductively heatable susceptor 18. An electrical connection is established between the induction coil 28 and the power source 54 of the vapour generating device 100, for example via electrical connectors, when the cartridge 10 is connected to the vapour generating device 100, for instance, via a releasable connection. By providing the induction coil 28 as an integral part of the cartridge 10, an optimum relative positioning of the induction coil 28 and the inductively heatable susceptor 18 may be achieved. This in turn ensures that a strong electromagnetic coupling is achieved between the generated electromagnetic field and the inductively heatable susceptor 18. The inductively heatable susceptor 18 may be spaced apart from the induction coil 28 by a distance of less than 4 mm, or preferably by a distance of less than 2 mm, or most preferably by a distance of less than 1 mm. Energy efficiency is improved as the distance separating the inductively heatable susceptor 18 and the induction coil 28 decreases. This helps to ensure that a strong electromagnetic coupling is achieved with the generated electromagnetic field. Accordingly, in examples of the disclosure the induction coil 28 more closely encapsulates the inductively heatable susceptor 18 and liquid transfer element 20.

In the illustrated example, the induction coil 28 is a helical coil. The induction coil 28 may have a shape which substantially corresponds to the shape of the inductively heatable susceptor 18. The induction coil 28 may be annular. The induction coil 28 may comprise a Litz wire or a Litz cable. It will, however, be understood that other materials could be used. The induction coil 28 may have an inner diameter of from 5 mm to 13 mm, or of from 6 mm to 12 mm, or preferably from 8 to 10 mm, or most preferably about 9 mm.

As will be understood by one of ordinary skill in the art, when the inductively heatable susceptor 18 is exposed to an alternating and time-varying electromagnetic field generated by the induction coil 28, eddy currents and/or magnetic hysteresis losses are generated in the inductively heatable susceptor 18 causing it to heat up. The heat is transferred from the inductively heatable susceptor 18 to the vapour generating liquid absorbed by the liquid transfer element 20, for example by conduction, radiation and convection, thereby heating and vaporising the vapour generating liquid. This arrangement provides a particularly convenient way to heat and vaporise the vapour generating liquid using induction heating.

A substantially cylindrical shaped, oval shaped or conical shaped susceptor geometry provides for a strong electromagnetic coupling with the generated electromagnetic field and a uniform transfer of heat to the liquid transfer element 20. The liquid transfer element 20 may have a shape substantially corresponding to the shape of the inductively heatable susceptor 18, for instance, the liquid transfer element 20 may be substantially cylindrical shaped, oval shaped or conical shaped.

In the illustrated example, the inductively heatable susceptor 18 is positioned outside the inner volume of the liquid store 12, and more particularly beneath the liquid store 12. An advantage of this arrangement is that it enables a strong electromagnetic coupling to be achieved with a generated electromagnetic field during use of the vapour generating system 110. Furthermore, in view of the proximity of the inductively heatable susceptor 18 and the induction coil 28, i.e., less than 4 mm apart, more magnetic lines from the induction coil 28 cross an area encircled by inductively heatable susceptor 18. Accordingly, better coupling between the induction coil 28 and the inductively heatable susceptor 18 is achieved, thus providing higher efficiency of energy transfer.

Eddy currents induced in the inductively heatable susceptor 18 by the induction coil 28 can flow around the entire circumference of the inductively heatable susceptor 18, for example via the uninterrupted paths, which results in more efficient heat generation. More efficient heat generation can allow for the design of smaller devices 100 with reduced power consumption.

The inductively heatable susceptor 18 comprises an electrically conductive material, and may comprise one or more, but not limited to, of aluminium, iron, nickel, mild steel, stainless steel, low carbon stainless steel, copper, and alloys thereof, e.g., Nickel Chromium or Nickel Copper.

The electromagnetic field generator 27 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.

In some examples, the liquid transfer element 20 comprises a capillary material, such as a porous ceramic material. Accordingly, the liquid transfer element 20 may be a porous liquid transfer element 20, such as a porous ceramic wick. The liquid transfer element 20 is therefore configured such that in use vapour generating liquid is transferred to the inductively heatable susceptor 18 by capillary action.

The liquid transfer element 20 includes an outer surface 24 which extends around the entire periphery of the liquid transfer element 20 and which is exposed to an inner space of the liquid store 12. In some examples, a sealing element (not shown) is provided which sealingly closes off the liquid store 12 to retain the vapour generating liquid in the liquid store 12. In such examples, the outer surface 24 of the liquid transfer element 20 is exposed to the inner space of the liquid store 12 by one or more openings or channels (not shown) formed in the sealing element. Vapour generating liquid is thereby absorbed into the liquid transfer element 20 via the outer surface 24 and is conveyed, for example by a wicking action, to the vaporisation device 14 so that it can be heated and vaporised producing a vapour which cools and condenses to form an aerosol which may then be inhaled.

The liquid transfer element 20 has a wall thickness sufficient to ensure a required level of mechanical strength. The liquid transfer element 20 may comprise a porous ceramic material, glass, high temperature plastics or high temperature foam (for instance neoprene foam). The material of the liquid transfer element 20 may be non-conductive.

In some examples, the liquid transfer element 20 comprises at least two different materials. A first of the materials is a porous ceramic. A second of the materials has a thermal conductivity and/or mechanical strength which is different from the porous ceramic.

Accordingly, in some examples the second of the materials has a thermal conductivity which is different from the porous ceramic. In other examples, the second of the materials has a mechanical strength which is different from the porous ceramic. In other examples, the second of the materials has a thermal conductivity and mechanical strength which are different from the porous ceramic. Such arrangements can provide a required mechanical strength and/or interrupt the undesirable thermal bridge between the liquid store 12 and the inductively heatable susceptor 18.

The second of the materials may comprise air pockets, which may be provided by microspheres. The air pockets may be provided by microspheres, i.e., bubbles. At least some of the bubbles may contact and bind to one another, thus creating a solid structure. Cavities between the bubbles define areas of porous ceramic material through which vapour generating liquid is transferred to the inductively heatable susceptor 18 by capillary action. The air pockets may be provided, for example, by glass, ceramic, or foam, such as glass foam or ceramic foam. In some examples, the at least two different materials of the liquid transfer element 20 are arranged as a composite or sandwich structure, wherein one part of the composite structure, i.e., a one of the materials, provides mechanical strength and wherein another part of the composite structure, i.e., another of the materials, provides a structure through which vapour generating liquid is transferrable to the inductively heatable susceptor 18 by capillary action.

In some examples, the liquid transfer element 20 is configured to withstand temperatures of at least 400°C without any change of shape or material properties. In other examples, the liquid transfer element 20 comprises or is formed of one material, for instance, which may be a porous ceramic material, glass, plastics or foam (for instance neoprene foam). The material may be configured to withstand temperatures of at least 400°C without any change of shape or material properties.

In some examples, the cartridge 10 comprises a dropper (not shown) configured to transfer a required amount of the vapour generating liquid from the liquid store 12 to the liquid transfer element 20.

The inductively heatable susceptor 18 is positioned outwardly, e.g., radially outwardly, of the liquid transfer element 20 and is arranged coaxially with respect to the central longitudinal axis of the cartridge 10. This ensures that the inductively heatable susceptor 18 is positioned in the region of highest electromagnetic field concentration and, thus, helps to ensure that a strong electromagnetic coupling is achieved with the generated electromagnetic field. In addition, mechanical stress on the liquid transfer element 20 resulting from thermal expansion of the inductively heatable susceptor 18 is substantially reduced or eliminated because the inductively heatable susceptor 18 expands outwardly, away from the liquid transfer element 20, when it is inductively heated. The risk of damage, e.g., cracking, being caused to the liquid transfer element 20 by the inductively heatable susceptor 18 when it thermally expands is thereby correspondingly substantially reduced or eliminated.

In the illustrated example, the inductively heatable susceptor 18 surrounds the liquid transfer element 20. More particularly, the inductively heatable susceptor 18 fully surrounds the liquid transfer element 20. By surrounding the outer surface 24 of the liquid transfer element 20 with the inductively heatable susceptor 18, an efficient and uniform transfer of heat, e.g., by conduction, from the inductively heatable susceptor 18 to the liquid transfer element 20 is achieved so that “hot spots” and “cold spots” are avoided. This in turn ensures that a sufficient amount of vapour is generated during use.

The inductively heatable susceptor 18 has an inner surface 22 that contacts the outer surface 24 of the liquid transfer element 20. Accordingly, the liquid transfer element 20 has an outer diameter corresponding to the inner diameter of the inductively heatable susceptor 18. The inner diameter of the inductively heatable susceptor 18 therefore defines the outer diameter of the liquid transfer element 20. The inductively heatable susceptor 18 is therefore in contact with the liquid transfer element 20. With this arrangement, there is no gap between the outer surface 24 of the liquid transfer element 20 and the inner surface 22 of the inductively heatable susceptor 18. Thus, heat can be readily conducted from the inductively heatable susceptor 18 to the liquid transfer element 20 thereby improving vapour generation and energy efficiency.

The inductively heatable susceptor 18 has an inner diameter of from 3 mm to 10 mm. Accordingly, the vapour generating unit 13 comprises a inductively heatable susceptor 18 with an inner diameter in the range of from 3 mm to 10 mm and further comprises a liquid transfer element 20, wherein the liquid transfer element 20 has an outer diameter corresponding to the inner diameter of the inductively heatable susceptor 18.

The larger the inner diameter of the inductively heatable susceptor 18, the greater the surface area which can be inductively heated to generate vapour, and thus the more vapour which can be potentially generated. However, since the outer diameter of the liquid transfer element 20 is defined by the inner diameter of the inductively heatable susceptor 18, the volume of the liquid transfer element 20 will also be increased by increasing the inner diameter of the inductively heatable susceptor 18. An increased amount of vapour generating liquid will thus be held and transferred to the vaporisation device 14 by the liquid transfer element 20 for heating by the inductively heatable susceptor 18. This may lead to an increased amount of time (and thus energy) required to heat the vapour generating liquid to generate vapour. An arrangement comprising a inductively heatable susceptor 18 having an inner diameter of from 3 mm to 10 mm and a liquid transfer element 20 having a corresponding outer diameter has surprisingly been found to provide an optimum balance between the quantity of vapour generated and the time (and thus energy) required to generate the vapour, thus improving performance. Furthermore, subsequent energy loss during cooling of the vapour generating liquid when the vapour generating system 110 is not in use is minimised.

In some examples, the inductively heatable susceptor 18 may have an inner diameter of from 5 mm to 8 mm, or of from 5.5 mm to 7.5 mm. In the illustrated example, the inductively heatable susceptor 18 has an inner diameter of about 7 mm. An inductively heatable susceptor 18 having these inner diameter dimensions (and a liquid transfer element 20 having a corresponding outer diameter) further optimises the balance between the quantity of vapour generated and the time (and thus energy) required to generate the vapour, thus further improving performance.

The liquid transfer element 20 has an outer diameter of from 3 mm to 10 mm, providing optimum performance of the liquid transfer element 20. The liquid transfer element 20 preferably may have an outer diameter of from 5 mm to 8 mm, or of from 5.5 mm to 7.5 mm. In the illustrated example, the liquid transfer element 20 has an outer diameter of about 7 mm.

The axial length of the inductively heatable susceptor 18 is less than the axial length of the outer surface 24 of the liquid transfer element 20. The term “axial length” means a length in the direction of the longitudinal axis of the cartridge 10. The inductively heatable susceptor 18 may have an axial length of from 0.5 mm to 15 mm. At the lower end of this range, the inductively heatable susceptor 18 may comprise susceptor rings. In some examples, the inductively heatable susceptor 18 may have an axial length of from 3 mm to 5 mm. In the illustrated example, the inductively heatable susceptor 18 has an axial length of about 4 mm. An inductively heatable susceptor 18 having these axial length dimensions may further optimise the balance between the quantity of vapour generated and the time (and thus energy) required to generate the vapour, thus further improving performance.

Referring to Figures 2a, 2b and 3, in some examples the cartridge 10 further comprises a cup 32 defining an airflow guide 34. The cartridge 10 illustrated in Figure 1 is shown with the cup 32 removed for illustrative purposes. The cup 32 is substantially cylindrical. The vapour generating unit 13 is disposed in the interior 30 of the cup 32, i.e., the inductively heatable susceptor 18 and the liquid transfer element 20 are disposed in the interior 30 of the cup 32. Air is flowable in use from the surrounding environment into the interior 30 of the cup 32 through one or more air inlets 33 (shown in Figure 3) to flow over the inductively heatable susceptor 18. In some examples, the one or more air inlets 33 may be disposed between the liquid store 12 and the inductively heatable susceptor 18. In use, air from the surrounding environment flowing through the one or more air inlets 33 helps interrupt the undesirable thermal bridge which may form between the liquid store 12 and the inductively heatable susceptor 18.

In the illustrated example, the inductively heatable susceptor 18 is spaced apart from the interior surface 25 of the cup 32. Accordingly, the inductively heatable susceptor 18 does not contact the cup 32. This provides a gap in the interior 30 of the cup 32 to facilitate airflow over the inductively heatable susceptor 18.

The cup 32 may comprise a heat resistant material. The cup 32 may comprise a plastics material, such as polyether ether ketone (PEEK), ceramic or glass. The cup 32 may be a glass tube.

The cup 32 is configured to ensure airflow is directed into a vaporisation chamber 40 defined by the liquid transfer element 20, further improving vapour generation and energy efficiency. In particular, the cup base 29 prevents linear airflow away from the vaporisation chamber 40. The cup 32 also prevents undesirable vapour leakage. Furthermore, this arrangement improves airflow over the inductively heatable susceptor 18, further improving vapour generation and energy efficiency.

As illustrated in Figure 3, in the illustrated example where the vapour generating device 100 comprises the induction coil 28, the induction coil 28 fully surrounds the cup 32 when the cartridge 10 is connected to the vapour generating device 100. In examples where the induction coil 28 is an integral part of, and belongs to, the cartridge 10, the induction coil 28 also fully surrounds the cup 26. The cup 32 may provide an induction coil housing, for instance defined by an outer surface of the cup 32.

In the illustrated example, the liquid transfer element 20 is toroidal and comprises a hollow core 36 and a base 38. The liquid transfer element 20 is substantially tubular. The hollow core 36 of the liquid transfer element 20 defines the vaporisation chamber 40.

The vaporisation chamber 40 may be substantially cylindrical and centrally positioned. The vaporisation chamber 40 is aligned with, and fluidly connected to, the vapour outlet channel 46. The vaporisation chamber 40 provides a route which allows vapour generated by heating the vapour generating liquid to be transferred into the vapour outlet channel 46 where it cools and condenses to form an aerosol that can be inhaled by a user via the mouthpiece 44. The vapour generated in the vaporisation chamber 40 may cool and condense to form an aerosol as it flows along the vapour outlet channel 46, from the vaporisation chamber 40 towards an end of the vapour outlet channel 46. Efficient vapour generation is thereby assured. In particular, a continuous process is achieved in which vapour generating liquid from the liquid store 12 is continuously absorbed by the liquid transfer element 20 and heated by the inductively heatable susceptor 18 to generate a vapour in the vaporisation chamber 40.

The vaporisation of the vapour generating liquid is facilitated by the addition of air from the surrounding environment through the one or more air inlets 33. The flow of air and/or vapour may be aided by negative pressure created by a user drawing air through the mouthpiece 44.

The base 38 of the liquid transfer element 20 comprises at least one indentation 42 which engages with the cup 32. The at least one indentation 42 is configured such that an airflow path is defined for allowing air to flow from the interior 30 of the cup 32 into the vaporisation chamber 40. Accordingly, in use air flows both over the outside and the inside of the liquid transfer element 20. The at least one indentation 42 may have a height of from 0. 1 mm to 5 mm, or preferably a height of from 0.5 mm to 2 mm. The at least one indentation 42 may have a width of from 0.5 mm to 10 mm, or preferably a width of from 1 mm to 3 mm.

In the illustrated example, the liquid transfer element 20 comprises a plurality of indentations 42. Accordingly, the base 38 of the liquid transfer element 20 is castellated. The base 38 of the liquid transfer element 20 may comprise from 2 to 20 indentations 42, or preferably from 8 to 12 indentations.

In operation of the vapour generating system 110, vapour generating liquid is conveyed from the liquid store 12 to the liquid transfer element 20. The vapour generating liquid is held and transferred by the liquid transfer element 20 (by capillary action) and is heated by the heat transferred to the liquid transfer element 20 from the inductively heatable susceptor 18. As noted above, when the cartridge 10 is used with a vapour generating device 100 including an induction coil 28, the inductively heatable susceptor 18 is inductively heated by the electromagnetic field generated by the induction coil 28. The heat from the inductively heatable susceptor 18 is transferred to vapour generating liquid held and transferred by the liquid transfer element 20, resulting in the generation of a vapour. The vapour escapes from the liquid transfer element 20 into the vaporisation chamber 40, and then flows from the vaporisation chamber 40 along the vapour outlet channel 46 where it cools and condenses to form an aerosol that is inhaled by a user through the mouthpiece 44. As illustrated in Figure 2b and 3, which shows airflow (indicated by arrows), the vaporisation of the vapour generating liquid is facilitated by the addition of air flowing from the surrounding environment through the one or more air inlets 33 into the interior 30 of the cup 32. Air flows from the interior 30 of the cup 32 into the vaporisation chamber 40 via the airflow path defined by the at least one indentation 42 comprised in the base 38 of the liquid transfer element 20. Air then flows from the vaporisation chamber 40 along the vapour outlet channel 46 to the mouthpiece 44. Vapour generated is entrained in the air as it flows from the interior 30 of the cup 32 into the vaporisation chamber 40 and along the vapour outlet channel 46 to the mouthpiece 44.

The flow of air and/or vapour through the cartridge 10, i.e., through the vaporisation chamber 40, along the vapour outlet channel 46, and out of the mouthpiece 44, is aided by negative pressure created by a user drawing air through the mouthpiece 44.

The figures also illustrate a method of manufacturing a cartridge 10 and a device 100 according to examples of the disclosure. The figures also illustrate a method of providing a system 110 according to examples of the disclosure.

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”.