Patent Description:
In many known aerosol-generating systems, a liquid aerosol-forming substrate is heated and vaporised to form a vapour. The vapour cools and condenses to form an aerosol. In some aerosol-generating systems, such as electrically heated smoking systems, this aerosol is then inhaled by a user.

Typically, the liquid aerosol-forming substrate comprises several compounds which are vaporised when heated. These compounds may have different boiling points. For example, a liquid aerosol-forming substrate may comprise nicotine (with a boiling point of around <NUM> degrees Celsius at atmospheric pressure) and glycerol (with a boiling point of around <NUM> degrees Celsius at atmospheric pressure).

When a liquid aerosol-forming substrate with compounds having different boiling points is heated, compounds with lower boiling points may be vaporised before compounds with higher boiling points. Alternatively, or in addition, compounds with lower boiling points may be vaporised at a higher rate than compounds with higher boiling points.

This may be undesirable because interactions and combinations between different compounds may be limited. For example, a liquid aerosol-forming substrate may comprise a nicotine compound and an organic acid compound, these compounds having different boiling points. Both of these compounds may be vaporised. The nicotine in the liquid aerosol-forming substrate may form free base nicotine when it is vaporised. However, it may be desirable to generate an aerosol with nicotine salt rather than free base nicotine. In order to form this nicotine salt, the free base nicotine may be protonated by the vaporised organic acid. However, this protonation may be limited if the organic acid is not vaporised until after nicotine has vaporised, or is vaporised more slowly than is required to protonate a suitable proportion of the free base nicotine.

Further, vaporising some compounds of an aerosol-forming substrate more quickly than others may undesirably cause the properties of the aerosol generated to change over time, for example over the course of a puff on an aerosol-generating system. This may be because, towards the beginning of a puff, when a heating element is activated and rises in temperature, liquid aerosol-forming substrate close to the heating element may reach a first temperature at which a first compound with a lower boiling point is vaporised but a second compound with a higher boiling point is not vaporised. Then, later in the puff, liquid aerosol-forming substrate close to the heating element may reach a second temperature at which the second compound with the higher boiling point is vaporised. However, at this time, much of the first compound in the liquid aerosol-forming substrate close to the heating element may have already been vaporised. Thus, towards the start of a puff, the aerosol generated may comprise a larger proportion of the first compound and, later in the puff, the aerosol generated may comprise a larger proportion of the second compound.

Alternatively, or in addition, the properties of the aerosol generated may change over the course of several puffs. This may occur where compounds of the liquid aerosol-forming substrate are not vaporised at an appropriate rate. For example, a liquid aerosol-forming substrate may comprise X percent by mass of a first compound and Y percent by mass of a second compound. If the liquid aerosol-forming substrate is not vaporised to produce a vapour comprising a mass ratio of the first compound to the second compound of X to Y, then the composition of the liquid aerosol-forming substrate may change as vapour is generated. This may, in turn, lead to a change in the properties of the aerosol generated by the liquid aerosol-forming substrate.

<CIT> relates to a heat-generating sheet for atomizing an aerosol-generating liquid. This document discloses a cartridge for an aerosol inhaler with a liquid reservoir that stores an aerosol-generating liquid, and a heat-generating sheet that is provided with a positive electrode and a negative electrode. By generating heat when a current flow is caused between the positive electrode and the negative electrode, the heat-generating sheet atomizes aerosol-generating liquid supplied thereto from the liquid reservoir. The heat-generating sheet is formed of a porous material, and slits are provided in the heat-generating sheet such that, while localization in the current density of current flowing between the positive electrode and the negative electrode is inhibited, a meandering electric path unit in a meandering shape is formed.

It is an aim of the invention to control the vaporisation of various compounds of a liquid aerosol-forming substrate, where these compounds have different boiling points.

Different aspects of the present disclosure are further discussed; these aspects are not necessarily covered by the claims.

According to an aspect of the present disclosure, there is provided a heater assembly. The heater assembly may be suitable for use in an aerosol-generating system. The heater assembly may comprise a liquid aerosol-forming substrate storage component. The heating element may comprise a first portion. The heating element may comprise a second portion. The first portion of the heating element may be embedded in the liquid aerosol-forming substrate storage component. The second portion of the heating element may be not embedded in the liquid aerosol-forming substrate storage component.

The heater assembly may provide areas of higher temperature, and areas of lower temperature, in the liquid aerosol-forming substrate storage component. Alternatively, or in addition, the heater assembly may provide areas which increase in temperature at a greater rate, and areas which increase in temperature at a lesser rate, in the liquid aerosol-forming substrate storage component.

Advantageously, the heater assembly may improve control of the vaporisation of the different compounds of the liquid aerosol-forming substrate. The heater assembly may result in liquid aerosol-forming substrate compounds with higher boiling points and lower boiling points being vaporised simultaneously at desirable rates. The heater assembly may result in liquid aerosol-forming substrate compounds with higher boiling points and lower boiling points being vaporised in more preferable proportions. The heater assembly may provide generation of an aerosol with a more desirable composition. The heater assembly may provide more consistent generation of an aerosol with desirable properties.

The heating element may comprise a third portion and a fourth portion. The third portion of the heating element may be embedded in the liquid aerosol-forming substrate storage component. The fourth portion may be not embedded in the liquid aerosol-forming substrate storage component.

Advantageously, this may create more areas of higher temperature, and more areas of lower temperature, in the liquid aerosol-forming substrate storage component. Alternatively, or in addition, this may provide more areas which increase in temperature at a greater rate, and more areas which increase in temperature at a lesser rate, in the liquid aerosol-forming substrate storage component. This may lead to liquid aerosol-forming substrate compounds with higher boiling points and lower boiling points being vaporised simultaneously at desirable rates.

The second portion of the heating element may extend between the first portion and the third portion. That is, the second potion of the heating element may connect the first portion of the heating element to the third portion of the heating element. The third portion may be connected to the first portion only via the second portion.

The third portion of the heating element may extend between the second portion and the fourth portion. That is, the third potion of the heating element may connect the second portion of the heating element to the fourth portion of the heating element. The fourth portion may be connected to the second portion only via the third portion.

The heating element, or one, or more than one, or all, of the first portion, the second portion, the third portion, and the fourth portion, may comprise an electrically resistive material. The heater assembly may be configured such that, in use, an electric current is passed through said portion or portions. This may resistively heat said portion or portions. As such, said portion or portions may be configured to be resistively heated.

One, or more than one, or all, of the first portion, the second portion, the third portion, and the fourth portion, of the heating element may be formed from the same material.

One, or more than one, or all, of the first portion, the second portion, the third portion, and the fourth portion, of the heating element may have substantially the same electrical resistivity (measured in Ohm metres). For example, the first portion and the second portion may have the same electrical resistivity. Alternatively, or in addition, the third portion and the fourth portion of the heating element may have the same electrical resistivity. As used here, the term "substantially the same electrical resistivity" is used to mean within <NUM>, <NUM>, or <NUM> percent of a given electrical resistivity.

The heating element, or one, or more than one, or all, of the first portion, the second portion, the third portion, and the fourth portion, of the heating element may comprise or be formed from any material with suitable electrical and mechanical properties, for example a suitable, electrically resistive 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, <NUM> Broadway Suite <NUM>, Denver Colorado. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated or coated with an insulating material or vice-versa, depending on the kinetics of energy transfer and the external physicochemical properties required. The heating element may comprise a metallic etched foil insulated between two layers of an inert material. In that case, the inert material may comprise Kaptone, all-polyimide or mica foil. Kapton® is a registered trade mark of E. du Pont de Nemours and Company, <NUM> Market Street, Wilmington, Delaware <NUM>, United States of America.

The third portion and the fourth portion may be configured to be resistively heated. The third portion and the fourth portion may comprise an electrically resistive material. The first portion and the second portion may be configured to be resistively heated. The first portion and the second portion may comprise an electrically resistive material.

The heating element, or one, or more than one, or all, of the first portion, the second portion, the third portion, and the fourth portion may comprise a susceptor material. The heater assembly may be configured such that, in use, said portion or portions are inductively heated.

For example, the heater assembly may be configured to be used in an aerosol-generating system comprising an inductor, such as an inductor coil. The inductor may be located in an aerosol-generating device having a power supply. The device may be configured to engage with the heater assembly or a cartridge comprising the heater assembly. Alternatively, the inductor may be located in a cartridge comprising the heater assembly. The cartridge may be configured to engage with an aerosol-generating device having a power supply.

The power supply may be configured to pass an alternating current through the inductor in the cartridge, or the inductor in the device, such that the inductor generates a fluctuating electromagnetic field.

The alternating current may have any suitable frequency. The alternating current may be a high frequency alternating current. The term high frequency alternating current may refer to a frequency between <NUM> kilohertz (kHz) and <NUM> megahertz (MHz). Where the inductor is a tubular inductor coil, the alternating current may have a frequency of between <NUM> kilohertz (kHz) and <NUM> megahertz (MHz). Where the inductor is a flat inductor coil, the alternating current may have a frequency of between <NUM> kilohertz (kHz), and <NUM> megahertz (MHz).

The heating element, or one, or more than one, or all, of the first portion, the second portion, the third portion, and the fourth portion, may be located within, or otherwise subjected to, the electromagnetic field generated by the inductor. This may generate eddy currents and hysteresis losses in the susceptor material. This may cause the susceptor material to heat up. Thus, the power supply and the inductor may be configured to inductively heat one, or more than one, or all, of the first portion, the second portion, the third portion, and the fourth portion.

The susceptor material may be, or may comprise, any material that can be inductively heated to a temperature sufficient to generate an aerosol from the aerosol-forming substrate. Preferred susceptor materials may be heated to a temperature in excess of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius. Preferred susceptor materials may comprise a metal or carbon or both a metal and carbon. A preferred susceptor material may comprise a ferromagnetic material, for example ferritic iron, or a ferromagnetic steel or stainless steel. A suitable susceptor element may be, or comprise, one or more of graphite, molybdenum, silicon carbide, stainless steels, niobium, and aluminium. Preferred susceptor materials may comprise, or be formed from, <NUM> series stainless steels, for example grade <NUM>, or grade <NUM>, or grade <NUM> stainless steel. Different materials will dissipate different amounts of energy when positioned within electromagnetic fields having similar values of frequency and field strength. Thus, parameters of the susceptor material such as material type and size may be altered to provide a desired power dissipation within a known electromagnetic field.

The third portion and the fourth portion may be configured to be inductively heated. The third portion and the fourth portion may comprise a susceptor material. The first portion and the second portion may be configured to be inductively heated. The first portion and the second portion may comprise a susceptor material.

Advantageously, in an aerosol-generating system which uses inductive heating, no electrical contacts need be formed between the heater assembly and the aerosol-generating device. In addition, the heating element may not need to be electrically joined to other components. This may eliminate the need for solder or other bonding elements. A cartridge incorporating a heater assembly which is configured to be inductively heated may allow production of a cartridge that is simple, inexpensive and robust. Cartridges are typically disposable articles produced in much larger numbers that the aerosol-generating devices with which they operate. Accordingly, reducing the cost of cartridges can lead to significant cost savings for manufacturers. In addition, inductive heating may provide improved energy conversion compared to resistive heating. This is because inductive heating may not have power losses associated with electrical resistance in connections between a resistive heating element and a power supply.

The heating element may have a length, a width, and a thickness. The heating element may comprise a strip of material. The strip may have a length, a width, and a thickness. The width may be perpendicular to the length. The thickness may be perpendicular to the length and the width. The length may be greater than the width. The width may be greater than the thickness.

A cross-section, or cross-sectional area, of the heating element may vary. For example, a cross-section, or cross-sectional area, of the heating element may vary along a length of the heating element.

The heating element may extend between a first end and a second end. For example, the length of the heating element may extend between a first end and a second end. The heating element may have a first cross-sectional area at a first point between the first end and the second end. The heating element may have a second cross-sectional area at a second point between the first point and the second end. The heating element may have a third cross-sectional area at a third point between the second point and the second end. The first cross-sectional area and the third cross-sectional area may each be greater than, or less than, the second cross-sectional area. For example, the first cross-sectional area and the third cross-sectional area may be at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent greater than, or at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent less than, the second cross-sectional area. Thus, observing how the cross-sectional area of the heating element varies from the first end to the second end of the heating element, the cross-sectional area of the heating element may decrease and then increase. Alternatively, or in addition, the cross-sectional area of the heating element may increase and then decrease.

Varying the cross-section, or cross-sectional area, of the heating element may result in different sections of the heating element simultaneously reaching different temperatures. For example, in a resistive heating element, a section of the heating element having a smaller cross-sectional area may have a larger resistance, and may therefore be resistively heated to a higher temperature.

Advantageously, this may create areas of higher temperature, and areas of lower temperature. Alternatively, or in addition, this may provide areas which increase in temperature at a greater rate, and areas which increase in temperature at a lesser rate, in the liquid aerosol-forming substrate storage component. As explained above, this may lead to liquid aerosol-forming substrate compounds with higher boiling points and lower boiling points being vaporised simultaneously at desirable rates.

A minimum cross-sectional area along a length of the heating element may be at least <NUM> percent less than a maximum cross-sectional area along the length of the heating element. A minimum cross-sectional area along a length of the heating element may be at least <NUM>, <NUM>, <NUM>, or <NUM> percent less than a maximum cross-sectional area along a length of the heating element.

A minimum cross-sectional area of the first portion of the heating element may be at least <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent less than a maximum cross-sectional area of the second portion or the fourth portion. Alternatively, or in addition, a minimum cross-sectional area of the third portion of the heating element may be at least <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent less than a maximum cross-sectional area of the second portion or the fourth portion.

A width or a thickness or both the width and the thickness of the heating element may vary along a length of the heating element.

The heating element may weave into and out of the liquid aerosol-forming substrate storage component. The heating element may comprise a strip of material which weaves into and out of the liquid aerosol-forming substrate storage component. The heating element or strip may weave into and out of the liquid aerosol-forming substrate storage component along its length. Thus, tracing along the length of the heating element or strip, the heating element or strip may alternately comprise portions embedded in the liquid aerosol-forming substrate storage component, such as the first portion and the third portion, and portions not embedded in the liquid aerosol-forming substrate storage component, such as the second portion and the fourth portion.

Advantageously, a heater assembly comprising a heating element which weaves into and out of a liquid aerosol-forming substrate storage component may be relatively straightforward to manufacture.

The heating element may comprise one or more of curves, undulations, folds, and corrugations. The first portion of the heating element may comprise one or more of a curve, an undulation, a fold, and a corrugation. The second portion of the heating element may comprise one or more of a curve, an undulation, a fold, and a corrugation. The third portion of the heating element may comprise one or more of a curve, an undulation, a fold, and a corrugation. The fourth portion of the heating element may comprise one or more of a curve, an undulation, a fold, and a corrugation. The fifth portion of the heating element may comprise one or more of a curve, an undulation, a fold, and a corrugation.

Advantageously, curves, undulations, folds, and corrugations in the heating element may allow greater control of the locations of areas of higher temperature and areas of lower temperature. Alternatively, or in addition, curves, undulations, folds, and corrugations in the heating element may allow greater control of the temperature differences between areas of higher temperature and areas of lower temperature. For example, if a higher temperature is desired in a given region of the liquid aerosol-forming substrate storage component, then the heating element may comprise an undulation or corrugation in this region. This may increase the volume or surface area of the heating element in this region, and therefore increase the heat transferred from the heating element to this region.

The heating element may have a first end and a second end. A length of the heating element may extend from the first end to the second end. Where the heating element does not extend directly from the first end to the second, i.e. in a straight line, the heating element may be considered to comprise one or more of curves, undulations, folds, and corrugations.

A curve may refer to a gradual change in direction of the heating element, for example a gradual change in direction of the heating element between the first end and the second end. Thus, a curve may form an arc, or a "C" shape.

A fold may refer to a step change in direction of the heating element, for example a step change in direction of the heating element between the first end and the second end. Thus, a fold may form two sides of a polygon, or a "V" shape.

An undulation may comprise multiple curves. For example, an undulation may refer to a gradual change in direction of the heating element in a first direction, followed by a gradual change in direction of the heating element in another, for example opposite, direction. Thus, an undulation may form a sinusoidal wave, or an "S" shape.

A corrugation may comprise multiple folds. For example, a corrugation may refer to a step change in direction of the heating element, followed by another step change in direction of the heating element. Thus, a corrugation may form three sides of a rectangle, or an "M" shape, or an "N" shape.

Advantageously, the heating element comprising one or more of curves, undulations, folds, and corrugations may simplify the manufacture of a heater assembly having at least one portion of a heating element embedded in a liquid aerosol-forming substrate storage component and at least one portion not embedded in the liquid aerosol-forming substrate storage component. Further, one or more of curves, undulations, folds, and corrugations may allow the heating element to create areas of higher temperature. For example, a portion of the heating element embedded in the liquid aerosol-forming substrate storage component may have a tightly curved "S" shape. The region of the liquid aerosol-forming substrate storage component around this portion of the heating element may be heated to a higher temperature.

The heating element may comprise one or more of irregular undulations and irregular corrugations along a length of the heating element. As used here, the terms irregular undulations and irregular corrugations refer to undulations and corrugations not having a constant amplitude and frequency.

The amplitude of an undulation or corrugation may be measured in a direction which is perpendicular to the length of the heating element. The amplitude of an undulation or corrugation may be measured in a direction of the thickness of the heating element. The amplitude may refer to half of the height difference between a peak, or local maximum, of an undulation or corrugation, and a trough, or local minimum, of the undulation or corrugation.

The frequency of an undulation or corrugation refers to the number of repeated cycles per unit distance, for example per unit distance in a direction of the length of the heating element or in a direction between the first end and the second end of the heating element. This type of frequency is often referred to as spatial frequency. For example, where the heating element comprises regular, sinusoidal waves, the waves are considered undulations and the frequency of those undulations is <NUM> divided by the wavelength of the waves.

An example of a regular undulation is a predictable, sinusoidal wave having a constant amplitude and frequency.

A frequency of undulations or corrugations of the heating element may vary along a length of the heating element.

An amplitude of undulations or corrugations of the heating element may vary along a length of the heating element.

Advantageously, varying the amplitudes, or frequencies, or both amplitudes and frequencies, may allow greater control of the locations of areas of higher temperature and areas of lower temperature. Alternatively, or in addition, varying the amplitudes, or frequencies, or both amplitudes and frequencies, may allow greater control of the temperature differences between areas of higher temperature and areas of lower temperature.

The heater assembly may comprise a reservoir for storing liquid aerosol-forming substrate. The heater assembly may comprise a reservoir of liquid aerosol-forming substrate.

The liquid aerosol-forming substrate storage component may store, or be configured to store, liquid aerosol-forming substrate.

The liquid aerosol-forming substrate storage component may be in fluid communication with the reservoir. In this case, in use, sections of the heating element which are further from the reservoir of liquid aerosol-forming substrate, or areas in the liquid aerosol-forming substrate storage component around these sections of the heating element, may reach higher temperatures than sections or areas which are closer to the reservoir of liquid aerosol-forming substrate. This is because more heat may be transferred, or heat may be transferred more quickly, from the heating element to the reservoir of liquid aerosol-forming substrate for sections of the heating element which are closer to the reservoir of liquid aerosol-forming substrate.

Advantageously, the liquid aerosol-forming substrate storage component being in fluid communication with the reservoir may allow liquid aerosol-forming substrate which is vaporised and removed from the liquid aerosol-forming substrate storage component to be replenished quickly and automatically.

The liquid aerosol-forming substrate storage component may comprise, or may be, a material soaked with, or a material configured to be soaked with, liquid aerosol-forming substrate. The liquid aerosol-forming substrate storage component may have a fibrous or spongy structure. The liquid aerosol-forming substrate storage component may comprise a capillary material. The liquid aerosol-forming substrate storage component may comprise a bundle of capillaries. For example, the liquid aerosol-forming substrate storage component may comprise one or more of fibres, threads, and fine bore tubes.

The liquid aerosol-forming substrate storage component may comprise sponge-like or foam-like material. The structure of the liquid aerosol-forming substrate storage component may form a plurality of small bores or tubes, through which the liquid can be transported by capillary action.

The liquid aerosol-forming substrate storage component may comprise any suitable material or combination of materials. Suitable materials include but are not limited to: 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 or ceramic. The liquid aerosol-forming substrate storage component may comprise a ceramic material. The liquid aerosol-forming substrate storage component may have any suitable capillarity and porosity so as to be used with different liquid aerosol-forming substrates having different physical properties.

The heating element may comprise a fifth portion, the fifth portion being located in the reservoir. The term "reservoir", unless explicitly stated otherwise, may be used to refer to a reservoir for storing liquid aerosol-forming substrate or a reservoir of liquid aerosol-forming substrate. The term "reservoir", unless explicitly stated otherwise, may be used to refer to a reservoir for storing a free-flowing liquid aerosol forming substrate, or to a reservoir of free-flowing liquid aerosol-forming substrate.

The reservoir may be configured to store, or may store, at least <NUM>, <NUM>, or <NUM> millilitres of liquid aerosol-forming substrate. The reservoir may be configured to store, or may store, less than <NUM>, <NUM>, or <NUM> millilitres of liquid aerosol-forming substrate.

The heating element may be perforated. The heating element may be a mesh heating element. The heating element may comprise a mesh. The first portion, or the second portion, or both the first portion and the second portion may comprise perforations, or a mesh. The third portion, or the fourth portion, or both the third portion and the fourth portion may comprise perforations, or a mesh.

Advantageously, a mesh heating element or a heating element comprising a mesh may provide a large surface area in contact with the liquid aerosol-forming substrate. This large surface area may provide efficient vaporisation of the liquid aerosol-forming substrate.

The heater assembly may comprise a second heating element. Features described in relation to the first heating element may be applied to the second heating element. Equally, features described in relation to portions of the first heating element may apply to corresponding portions, or parts, of the second heating element. For example, one or more of the material and shape of the first heating element may apply to the second heating element. Alternatively, the second heating element may have a different shape, or form, than the heating element.

Advantageously, a second heating element may increase the rate of vaporisation of liquid aerosol-forming substrate in the liquid aerosol-forming substrate storage component. In addition, a distance between the first heating element and the second heating element may be selected so as to influence a temperature of a region of the liquid aerosol-forming substrate storage component in use. For example, a region of the liquid aerosol-forming substrate storage component in which the first heating element and the second heating element are closer together may reach a higher temperature than a region in which the first heating element and the second heating element are spaced further apart.

The second heating element may comprise a first part. The second heating element may comprise a second part. The second heating element may comprise a third part. The second heating element may comprise a fourth part. The second heating element may comprise a fifth part.

The second part may extend between the first part and the third part. The third part may extend between the second part and the fourth part.

The first part of the second heating element may be embedded in the liquid aerosol-forming substrate storage component. The second part of the second heating element may be not embedded in the liquid aerosol-forming substrate storage component. The third part of the second heating element may be embedded in the liquid aerosol-forming substrate storage component. The fourth part of the second heating element may be not embedded in the liquid aerosol-forming substrate storage component. The fifth part of the second heating element may be located in the reservoir.

This may advantageously create more areas of relatively higher temperature and more areas of relatively lower temperature in the liquid aerosol-forming substrate storage component.

The second heating element may weave into and out of the liquid aerosol-forming substrate storage component.

The second heating element may comprise one or more of curves, undulations, folds, and corrugations.

The second heating element may be spaced from the heating element in a direction transverse to a length of the heating element. The second heating element may be spaced from the heating element in a width direction of the heating element. The second heating element may be located adjacent to the first heating element.

The second heating element may be a mesh heating element. The second heating element may comprise a mesh.

The first heating element and the second heating element may not be electrically connected.

The first heating element may be configured to be inductively heated. The first heating element may be configured to be inductively heated.

The first heating element and the second heating element may be independently operable. It may be possible to resistively or inductively heat the first heating element without substantially resistively or inductively heating the second heating element. It may be possible to raise a temperature of first heating element without substantially raising a temperature of the second heating element. The first heating element and the second heating element may be connected to different power sources.

The first portion, or the second portion, or both the first portion and the second portion of the heating element may be configured to be heated to at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius. In use, the first portion, or the second portion, or both the first portion and the second portion of the heating element may be heated to at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius.

The third portion, or the fourth portion, or both the third portion and the fourth portion of the heating element may be configured to be heated to at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius. In use, the third portion, or the fourth portion, or both the third portion and the fourth portion of the heating element may be heated to at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius.

The fifth portion of the heating element may be configured to be heated, and may, in use, be heated, to at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius. In use, the fifth portion of the heating element may be heated to at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius.

The liquid aerosol-forming substrate storage component may be configured to store, or may store, at least <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> millilitres of liquid aerosol-forming substrate.

According to another aspect of the present disclosure, there is provided a method of assembling a heater assembly. The heater assembly may be the heater assembly according to the present disclosure. The method may comprise providing a liquid aerosol-forming substrate storage component. The method may comprise providing a heating element comprising a first portion and a second portion. The method may comprise embedding the first portion of the heating element in the liquid aerosol-forming substrate storage component.

Where the heating element comprises the third portion, the method may comprise embedding the third portion of the heating element in the liquid aerosol-forming substrate storage component.

According to another aspect of the present disclosure, there is provided a cartridge. The cartridge may comprise a heater assembly according to the present disclosure.

The cartridge may be configured to engage with, and disengage from, an aerosol-generating device. The aerosol-generating device may comprise a power source. The power source may be configured to supply power to the heating element. The power source may be configured to supply power to the heating element only when the cartridge is engaged with the aerosol-generating device.

The cartridge may comprise an air inlet. The cartridge may comprise an air outlet. The air inlet may be in fluid communication with the air outlet. The heating element may be disposed downstream of the air inlet. The heating element may be disposed upstream of the air outlet. In use, this may allow air to flow in through the air inlet, then across, over, past, or through the heater assembly or heating element, then through the air outlet.

The cartridge may comprise a mouthpiece. The mouthpiece may comprise the air outlet. In use, when the cartridge is engaged with an aerosol-generating device, a user may puff on the mouthpiece of the cartridge. This may cause air to flow in through the air inlet, then across, over, past, or through the heater assembly or heating element, then through the air outlet.

Advantageously, providing an air flow across, over, past, or through the heater assembly or heating element may allow for entrainment of vapour formed by the heater assembly in the air flow.

The cartridge may comprise first and second electrical contacts electrically connected to the heating element. The electrical contacts may comprise one or more of tin, silver, gold, copper, aluminium, steel such as stainless steel, phosphor bronze, tin alloyed with antimony, tin alloyed with zirconium, tin alloyed with bismuth, or tin alloyed with other components improving resistance to organic acids.

The electrical contacts may be configured to form an electrical connection with corresponding electrical contacts on an aerosol-generating device when the cartridge is engaged with the aerosol-generating device.

The second portion, or the fourth portion, or both the second portion and the fourth portion of the heating element, may be located in an air flow path between the air inlet of the cartridge and the air outlet of the cartridge.

Advantageously, in use, this may increase the temperature of the air flow. Some users may prefer this. This may more accurately mimic the experience of smoking a conventional cigarette or cigar.

According to another aspect of the present disclosure, there is provided an aerosol-generating system. The system may comprise a heater assembly according to the present disclosure.

The aerosol-generating system may comprise a cartridge according to the present disclosure.

The system may comprise an aerosol-generating device. The system may comprise a cartridge comprising the heater assembly.

The cartridge may be configured to engage with the aerosol-generating device. The cartridge may be configured to disengage from the aerosol-generating device.

The aerosol-generating system, for example the aerosol-generating device of the aerosol-generating system, may comprise a power supply, such as a battery. The power supply may be configured to supply power to the heating element. This may be to heat the heating element. The power supply may be configured to supply power to the heating element only when the cartridge is engaged with the aerosol-generating device.

The aerosol-generating device may comprise a controller. The controller may be configured to control supply of power from the power supply. Thus, the controller may control heating of the heating element.

The power supply may be configured to supply power to the heating element to resistively heat the heating element. The power supply may be configured to supply power to the heating element to inductively heat the heating element.

The aerosol-generating device may be configured to engage to, and disengage from, the cartridge via a snap-fit connection, corresponding screw threads or any other suitable means. The aerosol-generating device may be configured to receive at least a portion of the cartridge. For example, the aerosol-generating device may comprise a chamber configured to receive at least a portion of the cartridge.

The aerosol-generating device may comprise an air inlet. The aerosol-generating device may comprise an air outlet. When the aerosol-generating device is engaged with the cartridge, the air outlet of the aerosol-generating device may be in fluid communication with the air inlet of the cartridge.

The power supply may be electrically connected to first and second electrical contacts of the device. These first and second electrical contacts may be configured to form an electrical connection with corresponding first and second electrical contacts on the cartridge when the cartridge is engaged with the device. These corresponding first and second electrical contacts on the cartridge may be electrically connected to the heating element. Thus, the power supply may be configured to supply power to the heating element by passing a current through the heating element.

The cartridge or the aerosol-generating device may comprise an inductor, for example an induction coil. The heating element may be, or may comprise, a susceptor material.

The power supply may be configured to pass a current, such as a high frequency alternating current, through the inductor such that the inductor generates a fluctuating electromagnetic field. This, in turn, may generate eddy currents and hysteresis losses in the susceptor material. This may cause the susceptor material to heat up. Thus, the power supply, using the inductor, may be configured to inductively heat the heating element.

Suitable susceptor materials include those mentioned earlier with reference to the heater assembly according to the present disclosure.

The inductor may be an induction coil. The inductor may be located in a cartridge comprising the heater assembly. The inductor may be disposed around the heating element, or around part of the heating element. For example, the inductor may be an induction coil and may spiral around the heating element, or around part of the heating element.

The inductor may be electrically connected to electrical contacts on the cartridge. When the cartridge is engaged with an aerosol-generating device, these electrical contacts may be electrically connected to corresponding electrical contacts on the device which are electrically connected to a power supply in the device. When the cartridge is engaged with the device, the power supply of the device may be configured to pass a current through the inductor to generate a fluctuating electromagnetic field and thereby heat the susceptor material of the heating element.

The inductor, such as an induction coil, may be located in the aerosol-generating device. The inductor may be electrically connected to a power supply of the aerosol-generating device. The aerosol-generating device may be configured to engage with the heater assembly or a cartridge comprising the heater assembly. For example, the device may comprise a chamber for receiving at least a portion of the heater assembly, or at least a portion of the cartridge comprising the heater assembly. The induction coil may be disposed around at least part of this chamber. For example, the induction coil may spiral around at least part of the chamber. As such, when the heater assembly, or the cartridge comprising the heater assembly, is engaged with the device, the induction coil may be disposed around, or spiral around, the heating element or part of the heating element. When at least a portion of the heater assembly, or at least a portion of a cartridge comprising the heater assembly, is received within the chamber of the device, the power supply of the device may be configured to pass a current through the inductor to generate a fluctuating electromagnetic field and thereby heat the susceptor material of the heating element.

As mentioned above, inductive heating may advantageously allow production of a cartridge that is simple, inexpensive and robust. In addition, inductive heating may provide improved energy conversion compared to resistive heating.

The aerosol-generating system may be a smoking system, for example an electrically operated smoking system. The aerosol-generating system may be for recreational use. In use, the aerosol-generating system may be suitable for delivering, or configured to deliver, nicotine to a user.

The aerosol-generating system may be portable. The aerosol-generating system may have a size comparable to a conventional cigar or cigarette. The smoking system may have a total length between <NUM> millimetres and <NUM> millimetres. The smoking system may have an external diameter between <NUM> millimetres and <NUM> millimetres. As used herein, the term "aerosol" refers to a dispersion of solid particles, or liquid droplets, or a combination of solid particles and liquid droplets, in a gas. The aerosol may be visible or invisible. The aerosol may include vapours of substances that are ordinarily liquid or solid at room temperature as well as solid particles, or liquid droplets, or a combination of solid particles and liquid droplets.

As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form an aerosol. The volatile compounds may be released by heating or combusting the aerosol-forming substrate.

The aerosol-forming substrate may comprise a plurality of compounds. The compounds may have different boiling points. For example, the aerosol-forming substrate may comprise a first compound with a first boiling point at atmospheric pressure and a second compound with a second boiling point at atmospheric pressure, the first boiling point being greater than the second boiling point.

The aerosol-forming substrate may comprise an aerosol former. As used herein, the term "aerosol-former" refers to any suitable compound or mixture of compounds that, in use, facilitates formation of an aerosol, for example a stable aerosol that is substantially resistant to thermal degradation at the temperature of operation of the system. Suitable aerosol-formers are well known in the art and include, but are not limited to: polyhydric alcohols, such as triethylene glycol, <NUM>,<NUM>-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.

The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise water. The aerosol-forming substrate may comprise glycerol, also referred to as glycerine, which has a higher boiling point than nicotine. The aerosol-forming substrate may comprise propylene glycol. The aerosol-forming substrate may comprise plant-based material. The aerosol-forming substrate may comprise homogenised plant-based material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a tobacco-containing material. The tobacco-containing material may contain volatile tobacco flavour compounds. These compounds may be released from the aerosol-forming substrate upon heating. The aerosol-forming substrate may comprise homogenised tobacco material. The aerosol-forming substrate may comprise other additives and ingredients, such as flavourants.

As used herein, the term "liquid aerosol-forming substrate" is used to refer to an aerosol-forming substrate in condensed form. Thus, the "liquid aerosol-forming substrate" may be, or may comprise, one or more of a liquid, gel, or paste. If the liquid aerosol-forming substrate is, or comprises, a gel or paste, the gel or paste may liquidise upon heating. For example, the gel or paste may liquidise upon heating to a temperature of less than <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius.

As used herein, the term "heating element" refers to an element of a heater, the element being configured to be heated. For example, the term "heating element" may refer to an element configured to be heated to at least <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> degrees Celsius. The heating element, or parts thereof, may be configured to be resistively heated. Alternatively, or in addition, the heating element, or parts thereof, may be configured to be inductively heated.

As used herein, the term "embedded" may be used to mean surrounded, enveloped, enclosed, circumscribed, or encircled. In addition, where a first component is "embedded" in a second component, this may imply that the first component is in contact with the second component. For example, where a portion of a heating element is described as embedded in a component, this may mean that this portion of the heating element is encircled by, and in contact with, the component.

Examples will now be further described with reference to the figures in which the embodiments of <FIG> are according to the present invention, whereas <FIG> are comparative examples not covered by the claims.

<FIG> shows a schematic, cross-sectional view of a first aerosol-generating system <NUM>. The aerosol-generating system <NUM> comprises an aerosol-generating device <NUM> and a cartridge <NUM>. In this example, the aerosol-generating system <NUM> is an electrically operated smoking system.

The aerosol-generating device <NUM> is portable and has a size comparable to a conventional cigar or cigarette. The device <NUM> comprises a battery <NUM>, such as a lithium iron phosphate battery, and a controller <NUM> electrically connected to the battery <NUM>. The device <NUM> also comprises two electrical contacts <NUM>, <NUM> which are electrically connected to the battery <NUM>. This electrical connection is a wired connection and is not shown in <FIG>.

The cartridge <NUM> comprises first and second electrical contacts <NUM>, <NUM>, an air inlet <NUM>, an air outlet <NUM>, and a first heater assembly <NUM>. The air inlet <NUM> is in fluid communication with the air outlet <NUM>. The heater assembly <NUM> is positioned downstream of the air inlet <NUM> and upstream of the air outlet <NUM>. The heater assembly <NUM> comprises a liquid aerosol-forming substrate storage component <NUM> in fluid communication with a reservoir <NUM> of liquid aerosol-forming substrate. The heater assembly <NUM> also comprises a heating element <NUM>. The first and second electrical contacts <NUM>, <NUM> are electrically connected to the heating element <NUM>.

In this system <NUM>, the liquid aerosol-forming substrate comprises around <NUM>% by weight glycerine, <NUM>% by weight propylene glycol, and <NUM>% by weight nicotine, though any suitable substrate could be used. At atmospheric pressure, nicotine has a boiling point of around <NUM> degrees centigrade, glycerine has a boiling point of around <NUM> degrees centigrade and propylene glycol has a boing point of around <NUM> degrees centigrade. Thus, when initially heating this liquid aerosol-forming substrate to form an aerosol, some systems may undesirably vaporise a disproportionately large amount of propylene glycol (which has the lowest boiling point of the compounds forming the substrate). This may lead to a less desirable aerosol being delivered to the user, such as an aerosol comprising a smaller proportion of nicotine than desired. This may also undesirably change the relative proportions of the compounds in the substrate over a longer time period. The present invention may eliminate or at least reduce these undesirable effects.

The heating element <NUM> is a strip of material. In this example, the material is stainless steel, though any suitable material could be used. The heating element <NUM> comprises a first portion <NUM>, a second portion <NUM>, a third portion <NUM>, and a fourth portion <NUM>. The second portion <NUM> extends between the first portion <NUM> and the third portion <NUM>. The third portion <NUM> extends between the second portion <NUM> and the fourth portion <NUM>. The first portion <NUM> and the third portion <NUM> are embedded in the liquid aerosol-forming substrate storage component <NUM>. The second portion <NUM> and the fourth portion <NUM> are not embedded in the liquid aerosol-forming substrate storage component <NUM>. In the example shown in <FIG>, the second portion <NUM> and the fourth portion <NUM> are located in an air flow path between the air inlet <NUM> and the air outlet <NUM> of the cartridge <NUM>.

In <FIG>, the aerosol-generating device <NUM> is engaged with the cartridge <NUM>. In this example, the cartridge <NUM> is engaged with the aerosol-generating device <NUM> via a screw thread <NUM> of the cartridge <NUM> mated with a corresponding screw thread <NUM> of the aerosol-generating device <NUM>.

The liquid aerosol-forming substrate storage component <NUM> in this example is a capillary material having a fibrous structure. In the example shown in <FIG>, the capillary material is formed form polyester, though any suitable material could be used.

In use, a user puffs on the air outlet <NUM> of the cartridge <NUM>. At the same time, the user presses a button (not shown) on the aerosol-generating device <NUM>. Pressing this button sends a signal to the controller <NUM>, which results in power being supplied from the battery <NUM> to the heating element <NUM> via the electrical contacts <NUM>, <NUM> of the device and the electrical contacts <NUM>, <NUM> of the cartridge. This causes a current to flow through the heating element <NUM>, thereby resistively heating the heating element <NUM>. In other examples, an air flow sensor, or pressure sensor, is located in the cartridge <NUM> and electrically connected to the controller <NUM>. The air flow sensor, or pressure sensor, detects that a user is puffing on the air outlet <NUM> of the cartridge <NUM> and sends a signal to the controller <NUM> to provide power to the heating element <NUM>. In these examples, there is therefore no need for the user to press a button to heat the heating element <NUM>.

As the heating element <NUM> is heated, areas of relatively higher temperature and areas of relatively lower temperature are created in the liquid aerosol-forming substrate storage component <NUM>. Areas of relatively lower temperature may be created in areas where the heating element <NUM> is closer to the reservoir <NUM> of liquid aerosol-forming substrate. This is because heat from the heating element <NUM> in these areas is dissipated into the reservoir <NUM> more quickly. Areas of relatively lower temperature may be created in areas which are further from the heating element. Areas of relatively higher temperature may be created due to the shape of the heating element. For example, the heating element may be shaped such that there is a greater volume, or greater surface area, of the heating element present in a given volume in a first location in the liquid aerosol-forming substrate storage component than in the same given volume in a second location in the liquid aerosol-forming substrate storage component. In this case, the average temperature of the liquid aerosol-forming substrate in the first location may be greater than the average temperature of the liquid aerosol-forming substrate in the second location.

The creation of areas of higher temperature and areas of lower temperature causes compounds of the liquid aerosol-forming substrate with higher boiling points and lower boiling points in the liquid aerosol-forming substrate storage component <NUM> to be vaporised simultaneously. The creation of areas of higher temperature and areas of lower temperature also causes compounds of the liquid aerosol-forming substrate with higher boiling points and lower boiling points in the liquid aerosol-forming substrate storage component <NUM> to be vaporised at desirable rates.

As the user puffs on the air outlet <NUM> of the cartridge <NUM>, air is drawn into the air inlet <NUM>. This air then travels across the heater assembly <NUM> and towards the air outlet <NUM>. This flow of air entrains the vapour formed by the heating element <NUM> heating liquid aerosol-forming substrate in the liquid aerosol-forming substrate storage component <NUM>. Due to the creation of areas of higher temperature and areas of lower temperature, as explained above, the vapour comprises desirable proportions of different compounds having different boiling points. This entrained vapour then cools and condenses to form an aerosol. This aerosol is then delivered to the user via the air outlet <NUM>. As liquid aerosol-forming substrate in the liquid aerosol-forming substrate storage component <NUM> is heated, vaporised, and entrained in the air flow, liquid aerosol-forming substrate from the reservoir <NUM> travels into the liquid aerosol-forming substrate storage component <NUM>. This liquid aerosol-forming substrate from the reservoir <NUM> effectively replaces the vaporised liquid aerosol-forming substrate. The liquid aerosol-forming substrate from the reservoir <NUM> may be drawn into the liquid aerosol-forming substrate storage component <NUM>, at least partly, by capillary action. This is because the liquid aerosol-forming substrate storage component <NUM> is a capillary material having a fibrous structure.

<FIG> shows a schematic, cross-sectional view of the first heater assembly <NUM>. The width of the heating element <NUM> which, in <FIG>, is in a direction into the page, could vary but, in the example shown in <FIG>, is constant. However, as shown in <FIG>, the thickness of the heating element <NUM> is not constant. Rather, the thickness gradually decreases from the second portion <NUM> to the third portion <NUM> and then gradually increases from the third portion <NUM> to the fourth portion <NUM>. The minimum thickness of the heating element <NUM> is in the third portion <NUM>, which is embedded in the liquid aerosol-forming substrate storage component <NUM>. This minimum thickness of the heating element <NUM> is around <NUM> percent of the maximum thickness of the heating element in the first portion <NUM>. Thus, the resistance of the third portion <NUM> is greater than the resistance of other portions, and, in use, the third portion <NUM> will be resistively heated to a greater temperature than other portions. This may advantageously increase the temperature of liquid aerosol-forming substrate close to the third portion <NUM> of the heating element <NUM>.

<FIG> shows a schematic, perspective view of the first heater assembly <NUM>. As shown in <FIG>, the heating element <NUM> comprises curves and weaves into and out of the liquid aerosol-forming substrate storage component <NUM>. Ends of the heating element <NUM> extend out of the liquid aerosol-forming substrate storage component <NUM> to enable easy electrical connection to electrical contacts (not shown in <FIG>) of the cartridge <NUM>.

<FIG> shows a schematic, cross-sectional view of a second aerosol-generating system <NUM>. The aerosol-generating system <NUM> comprises an aerosol-generating device <NUM> and a cartridge <NUM> incorporating a second heater assembly <NUM>. In this example, the aerosol-generating system <NUM> is an electrically operated smoking system.

The aerosol-generating device <NUM> is portable and has a size comparable to a conventional cigar or cigarette. The device <NUM> comprises a battery <NUM>, such as a lithium iron phosphate battery, and a controller <NUM> electrically connected to the battery <NUM>. The device <NUM> also comprises an induction coil <NUM> electrically connected to the battery <NUM>. The device <NUM> also comprises an air inlet <NUM> and an air outlet <NUM> in fluid communication with the air inlet <NUM>.

The cartridge <NUM> comprises an air inlet <NUM>, an air outlet <NUM>, and a second heater assembly <NUM>. The air inlet <NUM> is in fluid communication with the air outlet <NUM>. The heater assembly <NUM> is positioned downstream of the air inlet <NUM> and upstream of the air outlet <NUM>. When the cartridge <NUM> is engaged with the aerosol-generating device <NUM>, as shown in <FIG>, the air outlet <NUM> of the device <NUM> is adjacent to the air inlet <NUM> of the cartridge <NUM>. Thus, in use, when a user puffs on the air outlet <NUM> of the cartridge <NUM>, air flows through the air inlet <NUM> of the device <NUM>, then through the air outlet <NUM> of the device <NUM>, then through the air inlet <NUM> of the cartridge <NUM>, then past the heater assembly <NUM>, then through the air outlet <NUM> of the cartridge <NUM>.

In <FIG>, the cartridge <NUM> is engaged with the aerosol-generating device <NUM>. In this example, the cartridge <NUM> is engaged with the aerosol-generating device <NUM> via apertures <NUM>, <NUM> which form a snap-fit connection with corresponding protrusions <NUM>, <NUM> on the aerosol-generating device <NUM>.

The heater assembly <NUM> comprises a first heating element <NUM>, a second heating element (not visible in <FIG>), a reservoir <NUM> of liquid aerosol-forming substrate, and a liquid aerosol-forming substrate storage component <NUM> in fluid communication with the reservoir <NUM>. The second heating element <NUM> is not visible in <FIG>, but is visible in <FIG>.

In this system <NUM>, the liquid aerosol-forming substrate comprises around <NUM>% by weight glycerine and <NUM>% by weight nicotine, though any suitable substrate could be used. At atmospheric pressure, nicotine has a boiling point of around <NUM> degrees centigrade and glycerine has a boiling point of around <NUM> degrees centigrade. Thus, when initially heating this liquid aerosol-forming substrate to form an aerosol, some systems may undesirably vaporise a disproportionately large amount of nicotine (which has the lowest boiling point of the compounds forming the substrate). This may lead to a less desirable aerosol being delivered to the user. This may also undesirably change the relative proportions of the compounds in the substrate over a longer time period. The present invention may eliminate or at least reduce these undesirable effects.

The first heating element <NUM> comprises a strip of a susceptor material. In this example, the susceptor material is aluminium, though any suitable susceptor material could be used. The first heating element <NUM> comprises a plurality of portions embedded in the liquid aerosol-forming substrate storage component <NUM>, and a plurality of portions not embedded in the liquid aerosol-forming substrate storage component <NUM>. Of the portions which are not embedded in the liquid aerosol-forming substrate storage component <NUM>, two are located in the reservoir <NUM>.

In the example shown in <FIG>, the second heating element <NUM> is identical to the first heating element <NUM>, though two (or more) different heating elements could be used. The second heating element <NUM> is located adjacent to the first heating element <NUM>.

The liquid aerosol-forming substrate storage component <NUM> in this example is a capillary material having a fibrous structure. The capillary material is formed form polyester, though any suitable material could be used.

In use, a user puffs on the air outlet <NUM> of the cartridge <NUM>. At the same time, the user presses a button (not shown) on the aerosol-generating device <NUM>. Pressing this button sends a signal to the controller <NUM>, which results in the battery <NUM> supplying a high frequency electrical current to the induction coil <NUM>. This causes the induction coil <NUM> to create a fluctuating electromagnetic field. The first heating element <NUM> and the second heating element <NUM> are positioned within this field. Thus, this fluctuating electromagnetic field generates eddy currents and hysteresis losses in the first heating element <NUM> and the second heating element <NUM>. The first heating element <NUM> and the second heating element <NUM> are therefore inductively heated. In other examples, an air flow sensor, or pressure sensor, is located in the device <NUM> and electrically connected to the controller <NUM>. The air flow sensor, or pressure sensor, detects that a user is puffing on the air outlet <NUM> of the cartridge <NUM> and sends a signal to the controller <NUM> to supply the high frequency electrical current to the induction coil <NUM>, thereby heating the first heating element <NUM> and the second heating element <NUM>. In these examples, there is therefore no need for the user to press a button to heat the first heating element <NUM> and the second heating element <NUM>.

As the first heating element <NUM> and the second heating element <NUM> are heated, areas of relatively higher temperature and areas of relatively lower temperature are created in the liquid aerosol-forming substrate storage component <NUM>. Areas of lower temperature may be created in areas where the heating element <NUM> is closer to the reservoir <NUM> of liquid aerosol-forming substrate. This is because heat from the heating element <NUM> in these areas is dissipated into the reservoir <NUM> more quickly. Areas of relatively lower temperature may be created in areas which are further from the heating element. Areas of relatively higher temperature may be created due to the shape of the heating element. For example, the heating element may be shaped such that there is a greater volume, or greater surface area, of the heating element present in a given volume in a first location in the liquid aerosol-forming substrate storage component than in the same given volume in a second location in the liquid aerosol-forming substrate storage component. In this case, the average temperature of the liquid aerosol-forming substrate in the first location may be greater than the average temperature of the liquid aerosol-forming substrate in the second location.

As the user puffs on the air outlet <NUM> of the cartridge <NUM>, air is drawn into the air inlet <NUM> of the device <NUM>, then through the air outlet <NUM> of the device <NUM>, then through the air inlet <NUM> of the cartridge <NUM>. This air then travels around the heater assembly <NUM> and towards the air outlet <NUM>. This flow of air entrains the vapour formed by heating of the liquid aerosol-forming substrate by the first heating element <NUM> and the second heating element <NUM>. Due to the creation of areas of higher temperature and areas of lower temperature, as explained above, the vapour comprises desirable proportions of different compounds having different boiling points. This entrained vapour then cools and condenses to form an aerosol. This aerosol is then delivered to the user via the air outlet <NUM>.

<FIG> shows a schematic, cross-sectional view of a second heater assembly <NUM>.

The first heating element <NUM> comprises a first portion <NUM>, a second portion <NUM>, a third portion <NUM>, a fourth portion <NUM>, a fifth portion <NUM>, a sixth portion <NUM>, a seventh portion <NUM>, an eighth portion <NUM>, and a ninth portion <NUM>. The first portion <NUM>, the third portion <NUM>, the fifth portion <NUM>, the seventh portion <NUM>, and the ninth portion <NUM> are embedded in the liquid aerosol-forming substrate storage component <NUM>. The second portion <NUM>, fourth portion <NUM>, the sixth portion <NUM>, and the eighth portion <NUM> are not embedded in the liquid aerosol-forming substrate storage component <NUM>. The second portion <NUM> and the eighth portion <NUM> are located in an air flow path between the air inlet <NUM> and the air outlet <NUM> of the cartridge <NUM>. The fourth portion <NUM> and the sixth portion <NUM> are located in the reservoir <NUM> of liquid aerosol-forming substrate.

In <FIG>, the varying thickness of the first heating element <NUM> can be seen. The central section of the fifth portion <NUM> has a reduced thickness compared with the rest of the first heating element <NUM>. Specifically, the thickness in the central section of the fifth portion <NUM> has a thickness of around <NUM> percent of the thickness of the rest of the first heating element <NUM>. As shown in <FIG>, the fifth portion <NUM> also comprises corrugations. The region of the liquid aerosol-forming substrate storage component <NUM> around the fifth portion <NUM> may be raised to a relatively higher temperature than other regions of the liquid aerosol-forming substrate storage component <NUM>. This is because the fifth portion <NUM> of the heating element <NUM> being thinner may result in the fifth portion <NUM> being inductively heated to a higher temperature than other portions of the heating element <NUM>. Alternatively, or in addition, the corrugations in the fifth portion <NUM> mean that the region of the liquid aerosol-forming substrate storage component <NUM> around the fifth portion <NUM> comprises a greater volume and a greater surface area of the heating element <NUM> than other regions of the liquid aerosol-forming substrate storage component <NUM> with a similar size. Thus, more heat may be transferred from the heating element <NUM> into the region of the liquid aerosol-forming substrate storage component <NUM> around the fifth portion <NUM> than into other regions.

<FIG> shows a schematic, perspective view of the second heater assembly <NUM>. In <FIG>, the second heating element <NUM> is visible. The second heating element <NUM> is identical to the first heating element <NUM> and is located adjacent to the first heating element <NUM>. The second heating element <NUM> therefore similarly has portions embedded in the liquid aerosol-forming substrate storage component <NUM>, portions located in the reservoir <NUM>, and portions located in an air flow path between the air inlet <NUM> and the air outlet <NUM> of the cartridge <NUM>. In <FIG>, the second portion <NUM> and the eighth portion <NUM> of the first heating element <NUM> are also visible.

The heater assemblies described herein may provide areas of higher temperature, and areas of lower temperature, in the liquid aerosol-forming substrate storage component. Alternatively, or in addition, the heater assemblies may provide areas which increase in temperature at a greater rate, and areas which increase in temperature at a lesser rate, in the liquid aerosol-forming substrate storage component. Advantageously, as explained above, this may lead to liquid aerosol-forming substrate compounds with higher boiling points and lower boiling points being vaporised simultaneously at desirable rates.

Claim 1:
A heater assembly (<NUM>) for use in an aerosol-generating system (<NUM>), the heater assembly comprising:
a liquid aerosol-forming substrate storage component (<NUM>); and
a reservoir (<NUM>) of free-flowing liquid aerosol-forming substrate, the reservoir being in fluid communication with the liquid aerosol-forming substrate storage component;
a heating element (<NUM>) comprising a first portion (<NUM>), a second portion (<NUM>), and a further portion (<NUM>, <NUM>),
wherein the first portion of the heating element is embedded in the liquid aerosol-forming substrate storage component, the second portion of the heating element is not embedded in the liquid aerosol-forming substrate storage component, and the further portion of the heating element is located in the reservoir.