SUBSTRATES AND A PIERCING ELEMENT

The present invention relates to an aerosol-generating system, the aerosol-generating system comprising a cartridge having both solid and liquid aerosol-forming substrates, and an aerosol-generating device having a piercing element. The invention finds particular application as an electrically operated smoking system.

One type of aerosol-generating system is an electrically operated smoking system. Known handheld electrically operated smoking systems typically comprise an aerosol-generating device comprising a battery, control electronics and an electric heater for heating an aerosol- forming substrate. The aerosol-forming substrate may be contained within part of the aerosol- generating device. For example, the aerosol-generating device may comprise a liquid storage portion in which a liquid aerosol-forming substrate, such as a nicotine solution, is stored. Such devices, often referred to as 'e-cigarettes', typically contain sufficient liquid aerosol-forming substrate to provide a number of puffs equivalent to consuming multiple conventional cigarettes.

In an attempt to provide e-cigarette users with an experience that more closely simulates the experience of consuming a conventional cigarette some devices have attempted to combine an e-cigarette configuration with a tobacco-based substrate to impart a tobacco taste to the aerosol inhaled by the user. However, such devices may be impractically large and require the user to change a tobacco component and a liquid component at different times.

It would be desirable to provide an aerosol-generating system that mitigates or eliminates at least some of these problems with known devices.

According to a first aspect of the present invention there is provided an aerosol-generating system comprising a cartridge, an aerosol-generating device and a piercing element. The cartridge comprises a cartridge housing, a solid aerosol-forming substrate and a liquid aerosol- forming substrate each positioned within the cartridge housing, and a frangible seal. The aerosol- generating device comprises a device housing defining a cavity for receiving the cartridge, an electric heater, a power supply and a controller for controlling a supply of electrical power from the power supply to the electric heater. The piercing element is configured to pierce the frangible seal when the cavity receives the cartridge. The electric heater is positioned externally from the piercing element.

As used herein, the term "aerosol-forming substrate" is used to describe a substrate capable of releasing volatile compounds, which can form an aerosol. The aerosols generated from aerosol-forming substrates of aerosol-generating systems according to the invention may be visible or invisible and may include vapours (for example, fine particles of substances, which are in a gaseous state, that are ordinarily liquid or solid at room temperature) as well as gases and liquid droplets of condensed vapours. Aerosol-generating systems according to the present invention facilitate simultaneous replacement of a solid aerosol-forming substrate and a liquid aerosol-forming substrate by providing both substrates in a single cartridge. Advantageously, this may simplify use of the aerosol-generating system for a user when compared to known devices in which a tobacco-based substrate and a nicotine solution must be replaced or replenished separately.

Providing a solid aerosol-forming substrate and a liquid aerosol-forming substrate in a single cartridge may simplify replenishment of the liquid aerosol-forming substrate when compared to known devices in which a user may be required to refill a reservoir forming part of the device itself. Simplifying replenishment of the liquid aerosol-forming substrate may advantageously facilitate a reduction in the amount of liquid aerosol-forming substrate provided in the cartridge when compared to the amount of liquid aerosol-forming substrate provided in known devices. Advantageously, this may allow aerosol-generating systems according to the present invention to be smaller than known devices.

Aerosol-generating systems according to the present invention provide an electric heater that is separate from the cartridge. Advantageously, this may reduce the cost and simplify the manufacture of the cartridge when compared to known devices in which a heater and a liquid aerosol-forming substrate are combined into a single part of an aerosol-generating device. Advantageously, providing an electric heater that is separate from the cartridge may facilitate cleaning of the electric heater, which may facilitate use of the electric heater with multiple cartridges. The electric heater may form an integral part of the aerosol-generating device. The electric heater may be separable from the aerosol-generating device, for example to facilitate cleaning or replacement of the electric heater.

Advantageously, providing the cartridge with a frangible seal may reduce or prevent the loss of volatile compounds from one or both of the solid aerosol-forming substrate and the liquid aerosol-forming substrate. Advantageously, the piercing element may automatically pierce the frangible seal when the cartridge is inserted into the cavity of the aerosol-generating device for use.

The electric heater is positioned externally from the piercing element. That is, the electric heater is not positioned inside the piercing element. Advantageously, positioning the electric heater outside of the piercing element may facilitate cleaning of the electric heater.

Preferably, the aerosol-generating system comprises at least one airflow inlet and at least one airflow outlet. During use, air flows through the aerosol-generating system along a flow path from the airflow inlet to the airflow outlet. Air flows along the flow path from an upstream end of the flow path at the airflow inlet to a downstream end of the flow path at the airflow outlet. Preferably, the aerosol-generating system is configured so that, in use, the solid aerosol- generating substrate is positioned downstream of the liquid aerosol-generating substrate. The piercing element may have an elongate shape. The piercing element may comprise a hollow portion that defines an airflow passage through the piercing element. The piercing element may be solid.

The piercing element may comprise a shaft portion and a piercing portion at an end of the shaft portion. In embodiments in which the piercing element comprises a hollow portion, one or both of the piercing portion and the shaft portion may be hollow.

Preferably, the piercing portion has a first end connected to the shaft portion and a second end opposite the first end, wherein a cross-sectional area of the piercing portion decreases in size in a direction from the first end to the second end. Preferably, the second end of the piercing portion forms a point. Advantageously, providing the second end of the piercing portion with a small cross-sectional area may reduce the force required to pierce the frangible seal.

The piercing element may form part of the aerosol-generating device. The piercing element may extend from an end wall of the cavity, the piercing element extending into the cavity. Advantageously, providing the piercing element inside the cavity may reduce the risk of a user contacting the piercing element.

The electric heater may be provided on an outer surface of the piercing element. Advantageously, the piercing element may support the electric heater. The electric heater may comprise a resistive heating coil wound around a portion of the piercing element. In embodiments in which the piercing element comprises a shaft portion and a piercing portion, the resistive heating coil may be wound around part of the shaft portion.

The aerosol-generating device may comprise a liquid transfer element. The liquid transfer element is configured to contact the liquid aerosol-forming substrate when the cartridge is received within the cavity. The liquid transfer element may facilitate contact between the liquid aerosol-forming substrate and the electric heater during use. Preferably, the liquid transfer element is positioned in direct contact with the electric heater.

The liquid transfer element may form the piercing element.

In embodiments in which the piercing element forms part of the aerosol-generating device, the liquid transfer element may be provided adjacent the piercing element. The piercing element may extend through the liquid transfer element.

The aerosol-generating device may comprise a base plate positioned within the cavity, wherein the electric heater is positioned on the base plate and wherein the piercing element extends from the base plate. The base plate may be formed integrally with the piercing element. The piercing element may extend from a first side of the base plate. The electric heater may be positioned on a second side of the base plate. Preferably, the base plate comprises at least one aperture for the transfer of liquid aerosol-forming substrate through the base plate when the cartridge is received within the cavity. In embodiments in which the aerosol-generating device comprises a liquid transfer element, the liquid transfer element may be positioned on the base plate. The liquid transfer element may be positioned on the first side of the base plate. The piercing element may extend through the liquid transfer element.

The piercing element may form part of the cartridge. The piercing element may be configured to slide within the cartridge relative to the frangible seal when the cavity receives the cartridge. The cartridge may comprise a base plate and the piercing element extending from the base plate. The base plate may be formed integrally with the piercing element. Preferably, the base plate comprises at least one aperture for the transfer of liquid aerosol-forming substrate through the base plate when the cartridge is received within the cavity. Preferably, the aerosol- generating system is configured so that part of the aerosol-generating device acts upon the base plate when the cavity receives the cartridge. The aerosol-generating system may be configured so that the electric heater acts upon the base plate when the cavity receives the cartridge. In embodiments in which the aerosol-generating device comprises a liquid transfer element, the aerosol-generating system may be configured so that the liquid transfer element acts upon the base plate when the cavity receives the cartridge.

Preferably, the cartridge comprises a liquid storage housing positioned within the cartridge housing, wherein the liquid aerosol-forming substrate is positioned within the liquid storage housing and wherein the frangible seal is provided on the liquid storage housing. Preferably, the frangible seal is provided on an upstream end of the liquid storage housing.

Preferably, the liquid storage housing is retained within the cartridge housing by an interference fit.

Preferably, an outer surface of the liquid storage housing is shaped to define an airflow channel between the cartridge housing and the liquid storage housing when the liquid storage housing is received within the cartridge housing. The outer surface of the liquid storage housing may comprise a groove to define the airflow channel when the liquid storage housing is received within the cartridge housing.

The liquid storage housing may be tubular. The tubular liquid storage housing may have an open upstream end and a closed downstream end. Preferably, the frangible seal extends across the open upstream end.

The cartridge may comprises a porous carrier material positioned externally from the liquid storage housing and adjacent the frangible seal. Advantageously, the liquid aerosol-forming substrate may be sorbed into the porous carrier material when the piercing element pierces the frangible seal. Advantageously, the porous carrier material may substantially prevent liquid aerosol-forming substrate leaking from the aerosol-generating system when the piercing element pierces the frangible seal.

The porous carrier material may be retained in the cartridge housing by an interference fit.

The porous carrier material may be provided in a porous carrier material housing, wherein the porous carrier material housing is retained in the cartridge housing by an interference fit. The porous carrier material may be attached to the upstream end of the liquid storage housing.

In embodiments in which the piercing element forms part of the cartridge, preferably the piercing element extends through the porous carrier material. In embodiments in which cartridge comprises a base plate, preferably the porous carrier material is positioned between the base plate and the liquid storage housing.

In embodiments in which the aerosol-generating device comprises a liquid transfer element, preferably the aerosol-generating system is configured so that the liquid transfer element contacts the porous carrier material when the cartridge is received within the cavity.

The porous carrier material may have an annular shape defining a passage through the porous carrier material. Preferably, the aerosol-generating system is configured so that the piercing element extends through the passage when the cartridge is received within the cavity. This may be particularly advantageous in embodiments in which the aerosol-generating device comprises a liquid transfer element that forms the piercing element. Providing a passage extending through the porous carrier material may reduce the force required to push the piercing element through the porous carrier material.

The aerosol-generating system may be configured so that the porous carrier material is compressed when the cavity receives the cartridge. In embodiments in which the aerosol- generating system comprises a base plate, the base plate may exert a force on the porous carrier material when the cartridge is received within the cavity.

The cartridge may comprise an airflow channel positioned between the porous carrier material and the cartridge housing. In embodiments in which the porous carrier material is provided in a porous carrier material housing, the airflow channel may be positioned between the porous carrier material housing and the cartridge housing.

The porous carrier material may comprise any suitable material or combination of materials which is permeable to the liquid aerosol-forming substrate and allows the liquid aerosol- forming substrate to migrate through the porous carrier material. Preferably, the material or combination of materials is inert with respect to the liquid aerosol-forming substrate. The porous carrier material may or may not be a capillary material. The porous carrier material may comprise a hydrophilic material to improve distribution and spread of the liquid aerosol-forming substrate. This may assist with consistent aerosol formation. The particular preferred material or materials will depend on the physical properties of the liquid aerosol-forming substrate. Examples of suitable materials are a capillary material, for example a sponge or foam material, ceramic- or graphite-based materials in the form of fibres or sintered powders, a foamed metal or plastics material, a fibrous material, for example made of spun or extruded fibres, such as cellulose acetate, polyester, or bonded polyolefin, polyethylene, terylene or polypropylene fibres, nylon fibres or ceramic. The porous carrier material may have any suitable porosity so as to be used with different liquid physical properties.

In embodiments in which the aerosol-generating device comprises a liquid transfer element, the liquid transfer element may comprise any suitable material or combination of materials which is able to convey the liquid aerosol-forming substrate along its length. The liquid transfer element may be formed from a porous material, but this need not be the case. The liquid transfer element may be formed from a material having a fibrous or spongy structure. The liquid transfer element preferably comprises a bundle of capillaries. For example, the liquid transfer element may comprise a plurality of fibres or threads or other fine bore tubes. The liquid transfer element may comprise sponge-like or foam-like material. Preferably, the structure of the liquid transfer element forms a plurality of small bores or tubes, through which the liquid aerosol-forming substrate can be transported by capillary action. The particular preferred material or materials will depend on the physical properties of the liquid aerosol-forming substrate. Examples of suitable capillary materials include a sponge or foam material, ceramic- or graphite-based materials in the form of fibres or sintered powders, foamed metal or plastics material, a fibrous material, for example made of spun or extruded fibres, such as cellulose acetate, polyester, or bonded polyolefin, polyethylene, terylene or polypropylene fibres, nylon fibres, ceramic, glass fibres, silica glass fibres, carbon fibres, metallic fibres of medical grade stainless steel alloys such as austenitic 316 stainless steel and martensitic 440 and 420 stainless steels. The liquid transfer element may have any suitable capillarity so as to be used with different liquid physical properties. The liquid aerosol-forming substrate has physical properties, including but not limited to viscosity, surface tension, density, thermal conductivity, boiling point and vapour pressure, which allow the liquid aerosol-forming substrate to be transported through the liquid transfer element. The liquid transfer element may be formed from heat-resistant material. The liquid transfer element may comprise a plurality of fibre strands. The plurality of fibre strands may be generally aligned along a length of the liquid transfer element.

In embodiments in which the aerosol-generating system comprises a porous carrier material and a liquid transfer element, the porous carrier material and the liquid transfer element may comprise the same material. Preferably, the porous carrier material and the liquid transfer element comprise different materials.

The piercing element may be formed from any suitable material. In embodiments in which a liquid transfer element forms the piercing element, the piercing element may be formed from any suitable material described herein with respect to the liquid transfer element.

The piercing element may be formed from a metal. The piercing element may be formed from a plastic. Suitable materials include, but are not limited to, aluminium, stainless steel, polyether ether ketone (PEEK), polyimides, such as Kapton®, polyethylene terephthalate (PET), polyethylene (PE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), polyoxymethylene (POM), epoxy resins, polyurethane resins, vinyl resins, liquid crystal polymers (LCP) and modified LCPs, such as LCPs with graphite or glass fibres.

The frangible seal may extend across an opening defined by the cartridge housing or, where present, the liquid storage housing. The frangible seal may extend across an end of the cartridge housing or an end of the liquid storage housing. The frangible seal may be secured to the cartridge housing or the liquid storage housing about a periphery of the frangible seal. The frangible seal may be secured to the cartridge housing or the liquid storage housing by at least one of an adhesive and a weld, such as an ultrasonic weld. The frangible seal is preferably formed from a sheet material. The sheet material may comprise at least one of a polymeric film and a metallic foil.

The electric heater may comprise a resistive heating coil. The pitch of the coil is preferably between about 0.5 millimetres and about 1.5 millimetres, and most preferably about 1.5 millimetres. The pitch of the coil means the spacing between adjacent turns of the coil. The coil may comprise fewer than six turns, and preferably has fewer than five turns. The coil may be formed from an electrically resistive wire having a diameter of between about 0.10 millimetres and about 0.15 millimetres, preferably about 0.125 millimetres. The electrically resistive wire is preferably formed of 904 or 301 stainless steel. Examples of other suitable metals include titanium, zirconium, tantalum and metals from the platinum group. Examples of other suitable metal alloys include, Constantan, nickel-, cobalt-, chromium-, aluminium- titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese- and iron- containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetal®, iron- aluminium based alloys and iron-manganese-aluminium based alloys. The resistive heating coil may also comprise a metal foil, such as an aluminium foil, which is provided in the form of a ribbon.

The electric heater may comprise a resistive heating mesh. A resistive heating mesh may be advantageous in embodiments in which the electric heater is provided on a base plate.

The resistive heating mesh may comprise a plurality of electrically conductive filaments. The electrically conductive filaments may be substantially flat. As used herein, "substantially flat" means formed in a single plane and not wrapped around or otherwise conformed to fit a curved or other non-planar shape. A flat heating mesh can be easily handled during manufacture and provides for a robust construction.

The electrically conductive filaments may define interstices between the filaments and the interstices may have a width of between about 10 micrometres and about 100 micrometres. Preferably the filaments give rise to capillary action in the interstices, so that in use, liquid aerosol- forming substrate is drawn into the interstices, increasing the contact area between the heater assembly and the liquid. The electrically conductive filaments may form a mesh of size between about 160 Mesh US and about 600 Mesh US (+/- 10%) (that is, between about 160 and about 600 filaments per inch (+/- 10%)). The width of the interstices is preferably between about 75 micrometres and about 25 micrometres. The percentage of open area of the mesh, which is the ratio of the area of the interstices to the total area of the mesh is preferably between about 25 percent and about 56 percent. The mesh may be formed using different types of weave or lattice structures. The electrically conductive filaments may be an array of filaments arranged parallel to one another.

The electrically conductive filaments may have a diameter of between about 8 micrometres and about 100 micrometres, preferably between about 8 micrometres and about 50 micrometres, and more preferably between about 8 micrometres and about 39 micrometres.

The resistive heating mesh may cover an area of less than or equal to about 25 square millimetres. The resistive heating mesh may be rectangular. The resistive heating mesh may be square. The resistive heating mesh may have dimensions of about 5 millimetres by about 2 millimetres.

The electrically conductive filaments may comprise any suitable electrically conductive material. Suitable materials include but are not limited to: semiconductors such as doped ceramics, electrically "conductive" ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum and metals from the platinum group. Examples of suitable metal alloys include stainless steel, constantan, nickel-, cobalt-, chromium-, aluminium- titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese- and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetal®, iron-aluminium based alloys and iron-manganese-aluminium based alloys. Timetal® is a registered trade mark of Titanium Metals Corporation. The filaments may be coated with one or more insulators. Preferred materials for the electrically conductive filaments are 304, 316, 304L, and 316L stainless steel, and graphite.

The electrical resistance of the resistive heating mesh is preferably between about 0.3 and about 4 Ohms. More preferably, the electrical resistance of the mesh is between about 0.5 and about 3 Ohms, and more preferably about 1 Ohm.

The cartridge housing is preferably tubular and comprises an upstream end and a downstream end. Preferably, the solid aerosol-forming substrate is positioned within the downstream end. Preferably, the liquid aerosol-forming substrate is positioned within the upstream end. Where present, preferably the liquid storage housing and the porous carrier material are positioned within the upstream end of the cartridge housing. The solid aerosol-forming substrate may be retained in the cartridge housing by an interference fit.

The cartridge may comprise a filter positioned downstream of the solid aerosol-forming substrate. The filter may comprise a plug of filter material positioned within the downstream end of the cartridge housing. The plug of filter material may be retained within the cartridge housing by an interference fit. The filter may comprise a sheet material extending across a downstream opening of the cartridge housing. The sheet material may comprise a mesh. The sheet material may be secured to the cartridge housing by at least one of an adhesive and a weld, such as an ultrasonic weld. The filter may retain the solid aerosol-forming substrate in the cartridge housing.

The aerosol-generating system may comprise a mouthpiece. In embodiments in which the aerosol-generating system comprises at least one airflow outlet, preferably the mouthpiece comprises the at least one airflow outlet. The mouthpiece may form part of the cartridge. The mouthpiece may form part of the aerosol-generating device. The mouthpiece may be formed separately from the cartridge and the aerosol-generating device, wherein at least one of the cartridge and the aerosol-generating device is configured to receive the mouthpiece.

The solid aerosol-forming substrate may comprise tobacco. The solid aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds which are released from the substrate upon heating.

The solid aerosol-forming substrate may comprise tobacco containing deprotonated nicotine. Deprotonating the nicotine within tobacco may advantageously increase the volatility of the nicotine. Nicotine may be deprotonated by subjecting the tobacco to an alkalising treatment.

The solid aerosol-forming substrate may comprise a non-tobacco material. The solid aerosol-forming substrate may comprise tobacco-containing material and non-tobacco containing material.

The solid aerosol-forming substrate may include at least one aerosol-former. As used herein, the term 'aerosol former' is used to describe any suitable known compound or mixture of compounds that, in use, facilitates formation of an aerosol. Suitable aerosol-formers include, but are not limited to: polyhydric alcohols, such as propylene glycol, triethylene glycol, 1 ,3-butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate

Preferred aerosol formers are polyhydric alcohols or mixtures thereof, such as propylene glycol, triethylene glycol, 1 ,3-butanediol and, most preferred, glycerine.

The solid aerosol-forming substrate may comprise a single aerosol former. Alternatively, the solid aerosol-forming substrate may comprise a combination of two or more aerosol formers.

The solid aerosol-forming substrate may have an aerosol former content of greater than 5 percent on a dry weight basis. The solid aerosol-forming substrate may have an aerosol former content of between approximately 5 percent and approximately 30 percent on a dry weight basis.

The solid aerosol-forming substrate may have an aerosol former content of approximately 20 percent on a dry weight basis.

The liquid aerosol-forming substrate may comprise a tobacco-containing material comprising volatile tobacco flavour compounds which are released from the liquid upon heating. The liquid aerosol-forming substrate may comprise a non-tobacco material. The liquid aerosol- forming substrate may include water, solvents, ethanol, plant extracts and natural or artificial flavours. Preferably, the liquid aerosol-forming substrate comprises an aerosol former. Suitable aerosol formers include polyhydric alcohols or mixtures thereof, such as propylene glycol, triethylene glycol, 1 ,3-butanediol and glycerine.

The liquid aerosol-forming substrate may comprise nicotine.

The liquid aerosol-forming substrate may be free from nicotine. In such embodiments, the vaporised liquid aerosol-forming substrate may be drawn through the solid aerosol-forming substrate during use to strip one or more volatile compounds from the solid aerosol-forming substrate. The vaporised liquid aerosol-forming substrate may strip nicotine from the solid- aerosol-forming substrate. A solid aerosol-forming substrate comprising tobacco containing deprotonated nicotine may be particularly suited to embodiments in which the liquid aerosol- forming substrate is free from nicotine.

At least one of the solid aerosol-forming substrate and the liquid aerosol-forming substrate may comprise a flavourant. The flavourant may include menthol.

The power supply may comprise a battery. For example, the power supply may be a nickel-metal hydride battery, a nickel cadmium battery, or a lithium based battery, for example a lithium-cobalt, a lithium-iron-phosphate or a lithium-polymer battery. The power supply may alternatively be another form of charge storage device such as a capacitor. The power supply may require recharging and may have a capacity that allows for the storage of enough energy for use of the aerosol-generating device with more than one cartridge.

The invention is further described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of an aerosol-generating system according to a first embodiment of the invention and with the cartridge separate from the aerosol-generating device;

Figure 2 shows a perspective view of the aerosol-generating system of Figure 1 with the cartridge inserted into the aerosol-generating device;

Figure 3 shows a cross-sectional view of the aerosol-generating system of Figure 1 with the cartridge separate from the aerosol-generating device;

Figure 4 shows a cross-sectional view of the aerosol-generating system of Figure 1 with the cartridge inserted into the aerosol-generating device; Figure 5 shows an exploded view of the cartridge of the aerosol-generating system of Figure 1 ;

Figure 6 shows a cross-sectional view of an aerosol-generating system according to a second embodiment of the present invention and with the cartridge separate from the aerosol- generating device;

Figure 7 shows a cross-sectional view of the aerosol-generating system of Figure 6 with the cartridge inserted into the aerosol-generating device;

Figure 8 shows a cross-sectional view of an aerosol-generating system according to a third embodiment of the present invention and with the cartridge separate from the aerosol- generating device; and

Figure 9 shows a cross-sectional view of the aerosol-generating system of Figure 8 with the cartridge inserted into the aerosol-generating device.

Figures 1 and 2 show an aerosol-generating system 10 according to a first embodiment of the present invention. The aerosol-generating system 10 comprises an aerosol-generating device 12 and a cartridge 14. The aerosol-generating device 10 comprises a device housing 16 defining a cavity 18 for receiving an upstream end of the cartridge 14. Figure 1 shows the cartridge 14 separate from the aerosol-generating device 12 and Figure 2 shows the cartridge 14 received within the cavity 18 of the aerosol-generating device 12.

Figure 3 shows a cross-sectional view of the aerosol-generating system 10. The aerosol- generating device 12 comprises an airflow inlet 20 positioned at an upstream end of the device housing 16. A power supply 22 and a controller 24 are positioned within the upstream end of the device housing 16.

The aerosol-generating system 10 further comprises a piercing element 26 and an electric heater 28 in the form of a resistive heating coil. During use, the controller 24 controls a supply of electrical power from the power supply 22 to the electric heater 28. The piercing element 26 extends from an upstream end wall 27 of the cavity 18 and comprises a shaft portion 32 and a piercing portion 34. The resistive heating coil is wrapped around the shaft portion 32. The piercing element 26 also forms a liquid transfer element 30 and is formed from a material that facilitates transfer of liquid along the liquid transfer element 30 by capillary action.

The cartridge 14 comprises a cartridge housing 36, a solid aerosol-forming substrate 38, a liquid aerosol-forming substrate 40 and a porous carrier material 41 all positioned within the cartridge housing 36. Figure 5 shows an exploded view of the cartridge 14.

The solid aerosol-forming substrate 38 comprises a tobacco plug positioned within the downstream end of the cartridge housing 36. A mesh filter 42 is attached to a downstream end of the cartridge housing 36 to retain the tobacco plug within the cartridge housing 36.

The liquid aerosol-forming substrate 40 is contained within a liquid storage housing 44 retained within the upstream end of the cartridge housing 36 by an interference fit. The upstream end of the liquid storage housing 44 is open and the downstream end of the liquid storage housing 44 is closed. A frangible seal 48 extends across and is secured to the open upstream end of the liquid storage housing 44.

The porous carrier material 41 is positioned within a porous carrier material housing 50 retained within the cartridge housing 36 by an interference fit. The porous carrier material 41 is positioned upstream of the liquid storage housing 44. The porous carrier material housing 50 is open at both ends so that the downstream end of the porous carrier material 41 contacts the frangible seal 48. The porous carrier material 41 has an annular shape and defines a passage 54 through the porous carrier material 41.

Planar side walls 52 of the liquid storage housing 44 and the porous carrier material housing 50 are spaced apart from the inner surface of the cartridge housing 36 to define an airflow passage 53 between the cartridge housing 36 and each of the liquid storage housing 44 and the porous carrier material housing 50.

The downstream end of the cartridge housing 36 forms a mouthpiece 56, the mouthpiece 56 defining an airflow outlet 58 of the aerosol-generating system 10.

Figure 4 shows a cross-sectional view of the aerosol-generating system 10 after the cartridge 14 has been inserted into the cavity 18 of the aerosol-generating device 12. When the cartridge 14 is inserted into the cavity 18 the piercing element 26 pierces the frangible seal 48, which releases the liquid aerosol-forming substrate 40 from the liquid storage housing 44. The liquid aerosol-forming substrate is then sorbed into the porous carrier material 41. The piercing element 26 also functions as a liquid transfer element 30, which is received within the passage 54 extending through the porous carrier material 41. The liquid transfer element 30 transfers liquid aerosol-forming substrate 40 from the porous carrier material 41 to the electric heater 28 where it is vaporised for inhalation by a user. When a user draws on the mouthpiece 56, air is drawn into the aerosol-generating system 10 through the airflow inlet 20, through the aerosol- generating device 12 and into the cavity 18 where vaporised liquid aerosol-forming substrate is entrained in the airflow. The airflow then flows through the airflow passage 53 and through the solid aerosol-forming substrate 38 where further volatile compounds are entrained in the airflow, and out through the airflow outlet 58.

Figures 6 and 7 show a cross-sectional view of an aerosol-generating system 100 according to a second embodiment of the present invention. The aerosol-generating system 100 is similar to the aerosol-generating system 10 shown in Figures 1 to 5, and like reference numerals are used to designate like parts.

The aerosol-generating system 100 comprises a cartridge 1 14 that is substantially the same as cartridge 14 described with reference to Figure 5, except for the porous carrier material 141. In particular, the porous carrier material does not comprise a passage extending through the porous carrier material 141 . The aerosol-generating system 100 comprises an aerosol-generating device 1 12 that is similar to the aerosol-generating device 12 shown in Figures 1 to 4. The aerosol-generating device 1 12 comprises a base plate 127 mounted within the cavity 18 and a piercing element 126 extending from a first side of the base plate 127. A liquid transfer element 130 is also provided on the first side of the base plate 127, the piercing element 126 extending through the liquid transfer element 130. An electric heater 128 in the form of a resistive mesh heater is positioned on a second side of the base plate 127. The base plate 127 comprises a plurality of aperture extending through the base plate 127 to provide fluid communication between the liquid transfer element 130 and the electric heater 128.

Figure 7 shows the aerosol-generating system 100 with the cartridge 1 14 inserted into the cavity 18 of the aerosol-generating device 1 12. When the cartridge 1 14 is inserted into the cavity 18 the piercing element 126 pierces the frangible seal 48, which releases the liquid aerosol- forming substrate 40 from the liquid storage housing 44. The liquid aerosol-forming substrate is then sorbed into the porous carrier material 141. The liquid transfer element 130 contacts the upstream end of the porous carrier material 141 and transfers liquid aerosol-forming substrate 40 from the porous carrier material 141 to the electric heater 28 where it is vaporised for inhalation by a user. The airflow through the aerosol-generating system 100 is substantially the same as described herein with respect to the aerosol-generating system 10 shown in Figure 4.

Figures 8 and 9 show a cross-sectional view of an aerosol-generating system 200 according to a third embodiment of the present invention. The aerosol-generating system 200 is similar to the aerosol-generating system 100 shown in Figures 6 and 7, and like reference numerals are used to designate like parts.

The aerosol-generating system 200 differs by the position of the piercing element 226, which is provided in the cartridge 214 rather than the aerosol-generating device 212. As shown in Figure 8, the piercing element 226 is pre-inserted into the porous carrier material 141. Otherwise, the construction of the aerosol-generating system 200 is the same as the construction of the aerosol-generating system 100 shown in Figures 6 and 7.

Figure 9 shows the aerosol-generating system 200 with the cartridge 214 inserted into the cavity 18 of the aerosol-generating device 212. When the cartridge 214 is inserted into the cavity 18 the liquid transfer element 130 exerts a force upon the piercing element 226. The force exerted on the piercing element 226 slides the piercing element 226 within the porous carrier material housing 50 towards the frangible seal 48 until the piercing element 226 pierces the frangible seal 48. The operation of the aerosol-generating system 200 is then identical to the operation of the aerosol-generating system 100 of Figures 6 and 7.