WO2025021664A1

WO2025021664A1 - Aerosol-generating system with airflow cavity

Info

Publication number: WO2025021664A1
Application number: PCT/EP2024/070476
Authority: WO
Inventors: Onur DAYIOĞLU
Original assignee: Philip Morris Products SA
Current assignee: Philip Morris Products SA
Priority date: 2023-07-24
Filing date: 2024-07-18
Publication date: 2025-01-30
Anticipated expiration: 2026-01-24

Abstract

An aerosol-generating system (10) comprising: a cartridge (12) comprising: a cartridge housing; a liquid reservoir (25) configured to hold a liquid aerosol-forming substrate (26); and a heating element (31) configured to heat liquid (26) from the liquid reservoir (25); and a device (14) comprising: a device housing (38) defining a device cavity (40) configured to receive a portion of the cartridge (12); wherein: when the portion of the cartridge (12) is received in the device cavity (40), the aerosol-generating system (10) comprises an airflow path defined between an air inlet (48) and an air outlet (22); when the portion of the cartridge (12) is received in the device cavity (40), an airflow cavity (51) is located in the airflow path, the airflow cavity (51) being defined between the cartridge housing and the device housing (38); and the device (14) comprises a pressure sensor (52) arranged to detect the pressure in the airflow cavity (51).

Description

AEROSOL-GENERATING SYSTEM WITH AIRFLOW CAVITY

The present disclosure relates to an aerosol-generating system comprising a cartridge and a device. In particular, the present invention relates to an aerosol-generating system comprising an airflow cavity located in an airflow path, the airflow cavity being defined between a housing of the cartridge and a housing of the device.

Some known aerosol-generating systems comprise a cartridge holding a liquid aerosolforming substrate and an aerosol-generating device configured to receive the cartridge, wherein the system is configured to generate an aerosol from the liquid aerosol-forming substrate, typically by heating the liquid aerosol-forming substrate, when the cartridge is received in the aerosol-generating device.

In some known systems, the aerosol-generating device comprises a power supply, such as a battery, and a controller, and the cartridge comprises a heating element. The power supply and the controller of the aerosol-generating device are configured to supply power to the heating element for heating the heating element to heat the liquid aerosol-forming substrate. In use, when power is supplied to the heating element from the power supply, the heating element heats the liquid aerosolforming substrate, which releases volatile components that condense to form an aerosol, which is inhalable by a user.

In some known systems, the aerosol-generating system comprises an inductive heating assembly. In some of these known systems, the aerosol-generating device comprises a power supply, such as a battery, a controller, and an inductor coil, and the cartridge comprises a susceptor element. The inductor coil generates a varying magnetic field when supplied with a varying current, and the susceptor element is heated when it is arranged in the varying magnetic field. In use, the cartridge is inserted into a cavity of the aerosol-generating device, and a varying current is supplied to the inductor coil from the power supply to generate a varying magnetic field. The varying magnetic field penetrates the susceptor element, heating the susceptor element, which in turn heats the aerosol-forming substrate, releasing volatile components which condense to form an aerosol, which is inhalable by a user.

It would be desirable to provide an aerosol-generating system with an accurate and reliable way to detect when a user is taking a puff on the aerosol-generating system, so that the aerosolgenerating system can accurately control when power is supplied to a heating element or an inductive heating assembly. It would also be desirable to provide an aerosol-generating system that is capable of accurately detecting various characteristics of a puff of a user on the aerosol-generating system. According to the present disclosure, there is provided an aerosol-generating system. The aerosol-generating system may comprise a cartridge and a device. The cartridge may comprise a cartridge housing. The cartridge may comprise a liquid reservoir configured to hold a liquid aerosolforming substrate. The cartridge may comprise a heating element configured to heat liquid from the liquid reservoir. The device may comprise a device housing defining a device cavity configured to receive a portion of the cartridge. When the portion of the cartridge is received in the device cavity, the aerosol-generating system may comprise an airflow path defined between an air inlet and an air outlet. When the portion of the cartridge is received in the device cavity, an airflow cavity may be located in the airflow path. The airflow cavity may be defined between the cartridge housing and the device housing. The device may comprise a pressure sensor arranged to detect the pressure in the airflow cavity.

According to a preferred embodiment of the present disclosure, there is provided an aerosolgenerating system comprising a cartridge and a device. The cartridge comprises: a cartridge housing; a liquid reservoir configured to hold a liquid aerosol-forming substrate; and a heating element configured to heat liquid from the liquid reservoir. The device comprises a device housing defining a device cavity configured to receive a portion of the cartridge. When the portion of the cartridge is received in the device cavity, the aerosol-generating system comprises an airflow path defined between an air inlet and an air outlet. When the portion of the cartridge is received in the device cavity, an airflow cavity is located in the airflow path, the airflow cavity being defined between the cartridge housing and the device housing. The device comprises a pressure sensor arranged to detect the pressure in the airflow cavity.

Providing an aerosol-generating system with a pressure sensor configured to detect the pressure in an airflow path through the aerosol-generating system may enable the aerosol-generating system to detect when a user is taking a puff on the aerosol-generating system. Advantageously, providing an airflow cavity in the airflow path of the aerosol-generating system, wherein the airflow cavity is defined between a portion of the cartridge housing and a portion of the device housing, may enable one or both of the cartridge and the device to be made smaller or more compact compared to a system in which the airflow cavity is formed entirely by the cartridge housing or entirely by the device housing.

As used herein, “aerosol-generating system” refers to a system that interacts with an aerosolforming substrate to generate an aerosol. Preferably, the aerosol-generating system is a system that interacts with an aerosol-forming substrate to generate an inhalable aerosol that is directly inhalable into a user’s lungs thorough the user's mouth. As used herein, an aerosol-generating system comprises a cartridge and a device. As used herein, “aerosol-forming substrate” refers to a substrate capable of releasing volatile compounds that can form an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. Unless stated otherwise, in this disclosure an aerosol-forming substrate refers to a liquid aerosol-forming substrate, which is typically stored in a reservoir in a cartridge.

As used herein, the term “cartridge” refers to an article comprising an aerosol-forming substrate that is capable of releasing volatile compounds that can form an aerosol. A cartridge may be disposable.

As used herein, the terms “upstream” and “downstream” are used to describe the relative positions of components, or portions of components, of an aerosol-generating system. The terms upstream and downstream are relative to the direction of airflow or the flow of aerosol through the aerosol generating system when a user draws on the air outlet of the airflow path through the aerosolgenerating system. The air outlet of the airflow path is downstream of the air inlet of the airflow path. The airflow cavity of the airflow path is downstream of the air inlet of the airflow path. The airflow cavity of the airflow path is upstream of the air outlet of the airflow path. The air inlet of the airflow path is upstream of the air outlet of the airflow path.

As used herein, the term “puff” is used to describe the action of a user of the aerosolgenerating system drawing on the air outlet of the airflow path to receive and inhale aerosol generated by the aerosol-generating system.

As used herein, “length” refers to the maximum dimension of a feature in a longitudinal direction of the feature.

As used herein, “width” or “diameter” refers to the maximum dimension of a feature in a transverse direction of the feature. The transverse direction is perpendicular to the longitudinal direction.

As used herein, “thickness” and “depth” refer to the maximum dimension of a feature in a direction perpendicular to the longitudinal direction of the feature and perpendicular to the transverse direction of the feature.

In some preferred embodiments, the pressure in the airflow path is at a minimum in the airflow cavity when air is drawn through the airflow path between the air inlet and the air outlet. In other words, the region of minimum pressure through the airflow path when air is drawn through the airflow path is at the airflow cavity.

In some particularly preferred embodiments, a flow restriction is arranged in the airflow path between the air inlet and the airflow cavity. The flow restriction may be configured to cause a pressure drop in the airflow cavity when air is drawn through the airflow path. The pressure drop at the airflow cavity may result in the pressure in the airflow path being at a minimum in the airflow cavity. Advantageously, detecting the pressure in the airflow cavity after a flow restriction in the airflow path, and particularly at the point of minimum pressure along the airflow path, may provide more accurate puff detection by the aerosol-generating system. Advantageously, detecting the pressure in the airflow cavity after a flow restriction in the airflow path, and particularly at the point of minimum pressure along the airflow path, may provide more prompt puff detection by the aerosolgenerating system. Detecting the pressure after the flow restriction, and particularly at the point of minimum pressure along the airflow path, may enable detection of the pressure drop caused by the flow restriction, which may be used to detect when a user is taking a puff on the aerosol-generating system.

Advantageously, detecting the pressure after a flow restriction of the airflow path may provide more accurate information on the puff of a user on the aerosol-generating device. Detecting the pressure after the flow restriction may enable detection of the pressure drop caused by the flow restriction, which may be used to determine puff characteristics, such as the volume of air drawn through the flow restriction.

The flow restriction may be any suitable flow restriction that causes a pressure drop in the airflow path that is measurable by the pressure sensor when a user takes a puff on the aerosolgenerating system.

When a user inhales on an aerosol-generating system they experience a draw resistance. This resistance can be quantified as a measure of the pressure drop through the aerosol-generating system for a given volumetric flow rate through the system, known as the resistance to draw (RTD). An acceptable RTD for consumer comfort is typically in the range of 60 to 100 millimetres of water gauge (mmWg).

Unless otherwise specified, the resistance to draw (RTD) of the aerosol-generating system or the airflow path, or the cartridge, or any other component of the aerosol-generating system is measured in accordance with ISO 6565-2015. The RTD refers to the pressure required to force air through the full length of a component. The terms “pressure drop” or “draw resistance” of a component may also refer to the “resistance to draw”. Such terms generally refer to the measurements in accordance with ISO 6565-2015 are normally carried out under test at a volumetric flow rate of about 17.5 millilitres per second at the output or downstream end of the measured component, at an ambient temperature of about 22 degrees Celsius, a pressure of about 101 kPa (about 760 Torr) and a relative humidity of about 60 percent.

The flow restriction may be configured to cause a pressure drop of at least 70 pascals (Pa), at least 80 pascals (Pa), at least 90 pascals (Pa), at least 100 pascals (Pa) (10 millimetres of water gauge), at least 150 pascals (Pa), at least 200 pascals (Pa), at least 250 pascals (Pa), or at least 300 pascals (Pa) during a typical puff of a user. The flow restriction may be arranged at any suitable location in the airflow path. Preferably, the flow restriction is arranged immediately upstream of the airflow cavity. In some embodiments, the flow restriction may be spaced from the airflow cavity.

In some embodiments, the aerosol-generating device comprises the flow restriction. In some of these embodiments, a portion of the device housing defines the flow restriction.

In some embodiments, the flow restriction is defined between the cartridge housing and the device housing. When the portion of the cartridge is received in the device cavity, the flow restriction may be defined between the cartridge housing and the device housing. In some embodiments, at least a portion of a surface of the cartridge housing defines at least a portion of a surface of the flow restriction. In some embodiments, at least a portion of a surface of the device housing defines at least a portion of a surface of the flow restriction.

The flow restriction may be a portion of the airflow path having a width that is smaller than the width of the airflow cavity. The flow restriction may be a portion of the airflow path having the smallest width of any portion of the airflow path.

The flow restriction may be a portion of the airflow path having a cross-sectional area that is smaller than the cross-sectional area of the airflow cavity. The flow restriction may be a portion of the airflow path having the smallest cross-sectional area of any portion of the airflow path.

The flow restriction may have any suitable width. The flow restriction may have a width of between 0.15 millimetres and 0.8 millimetres.

The flow restriction may have any suitable depth, The flow restriction may have a depth of between 0.3 millimetres and 1.2 millimetres.

The flow restriction may have any suitable length, The flow restriction may have a length of between 1 millimetres and 2 millimetres.

The flow restrictions may have any suitable cross-sectional area. The flow restriction may have a cross-sectional area of between 0.045 millimetres squared and 1 millimetre squared.

The flow restriction may comprise a narrow portion of the airflow path through the aerosolgenerating device, having a width or a diameter smaller than the width or the diameter of at least one of a portion of the airflow path immediately before the flow restriction and a portion of the airflow path immediately after the flow restriction. The flow restriction may comprise a narrow portion having a width or a diameter smaller than the width or the diameter of the airflow path immediately before the flow restriction. The flow restriction may comprise a narrow portion having a width or a diameter smaller than the diameter of the airflow path immediately after the flow restriction. The flow restriction may comprise a plurality of narrow portions, each narrow portion having a width or a diameter smaller than the width or the diameter of the airflow path immediately before the flow restriction and the width or the diameter of the airflow path immediately after the flow restriction. Preferably, the flow restriction comprises a narrow portion of the airflow path having the smallest width or diameter of the airflow path.

The flow restriction may comprise a narrow portion of the airflow path through the aerosolgenerating device, having a cross-sectional area smaller than the cross-sectional area of at least one of a portion of the airflow path immediately before the flow restriction and a portion of the airflow path immediately after the flow restriction. The flow restriction may comprise a narrow portion having a cross-sectional area smaller than the cross-sectional area of the airflow path immediately before the flow restriction. The flow restriction may comprise a narrow portion having a cross-sectional area smaller than the cross-sectional area of the airflow path immediately after the flow restriction. The flow restriction may comprise a plurality of narrow portions, each narrow portion having a cross- sectional area smaller than the cross-sectional area of the airflow path immediately before the flow restriction and the cross-sectional area of the airflow path immediately after the flow restriction.

Preferably, the flow restriction comprises a narrow portion of the airflow path having the smallest cross-sectional area of the airflow path.

The aerosol-generating system comprises an airflow cavity in the airflow path. The airflow cavity is located in the airflow path. The airflow cavity is defined between the cartridge housing and the device housing when the portion of the cartridge is received in the device cavity. In some embodiments, at least a portion of a surface of the cartridge housing defines at least a portion of a surface of the airflow cavity. In some embodiments, at least a portion of a surface of the device housing defines at least a portion of a surface of the airflow cavity. The airflow cavity may have any suitable size and shape.

The aerosol-generating system comprises a heating element. Preferably, at least a portion of a surface of the heating element is arranged to contact air in the airflow path. The heating element may be arranged at any suitable location in the airflow path. A portion of a surface of the heating element may form a portion of a surface of the airflow path. A portion of the heating element may be arranged in the airflow path. In some preferred embodiments, the heating element is arranged between the airflow cavity and the air outlet. In some preferred embodiments, the heating element is arranged after the airflow cavity. In other words, the heating element is preferably arranged downstream of the airflow cavity. Advantageously, arranging the heating element downstream of the airflow cavity may reduce the vapour or aerosol generated at the heating element from passing through the airflow cavity and coming into contact with the pressure sensor. This may help to protect the pressure sensor from damage due to contact with hot vapour or aerosol.

In some embodiments, the aerosol-generating device may comprise two flow restrictions, a first flow restriction as described above, and a second flow restriction after the airflow cavity. The second flow restriction may be arranged between the airflow cavity and the air outlet. The second flow restriction may be arranged downstream of the airflow cavity. Accordingly, the pressure sensor may be arranged to detect the pressure drop in the airflow path resulting from the first flow restriction, rather than the second flow restriction. The second flow restriction may help to prevent backflow of vapour or aerosol generated in the device cavity from entering the airflow cavity between puffs on the aerosol-generating device. As such, the second flow restriction may help to keep the pressure sensor clean by keeping the pressure sensor away from generated vapour and aerosol.

The pressure sensor may comprise any suitable type of pressure sensor. The pressure sensor may be an absolute pressure sensor, configured to determine the absolute pressure in the airflow cavity. The pressure sensor may be a gauge pressure sensor, configured to detect the relative pressure in the airflow cavity compared to an ambient pressure adjacent the aerosol-generating system. The pressure sensor may be a differential pressure sensor, configured to detect a difference in pressure between the airflow cavity and another first position in the airflow path. The pressure sensor may be a capacitive pressure sensor. The pressure sensor may be a piezoresistive pressure sensor. The pressure sensor may be a strain gauge. Preferably, the pressure sensor is a micro electronic mechanical systems (MEMS) pressure sensor. Advantageously, a MEMS pressure senso may be small enough to fit into the aerosol-generating device without significantly increasing the size of the aerosol-generating device. An example of a suitable absolute pressure sensor is the MEMS nano pressure sensor LPS22HBTR, manufactured by STMicroelectronics, which has an operating pressure of between about 26 kilopascals (kPa) and about 126 kilopascals (kPa), and dimensions of 2 millimetres by 2 millimetres by 0.76 millimetres.

The pressure sensor is configured to detect the pressure in the airflow cavity of the airflow path.

In some embodiments, the pressure sensor is configured to detect a differential pressure in the airflow path. In some embodiments, the pressure sensor is configured to detect the pressure in the airflow path before the airflow cavity and in the airflow cavity. In some of these embodiments, the pressure sensor comprises a first pressure sensor configured to detect the pressure in the airflow cavity and a second pressure sensor configured to detect the pressure before the airflow cavity or upstream of the airflow cavity.

In some embodiments comprising a flow restriction between the air inlet and the airflow cavity, the pressure sensor is configured to detect the pressure in the airflow path before the flow restriction or upstream of the flow restriction and in the airflow cavity. In some of these embodiments, the pressure sensor comprises a first pressure sensor configured to detect the pressure in the airflow cavity and a second pressure sensor configured to detect the pressure before the flow restriction or upstream of the flow restriction. Advantageously, a differential pressure measurement taken between two locations in the airflow path may not be affected by the local environmental conditions, such as altitude and humidity. Accordingly, where a differential pressure measurement is taken, the pressure sensor may not require re-calibration for use in different environments, such as at different altitudes.

When the portion of the cartridge is received in the device cavity, the aerosol-generating system comprises an airflow path defined between an air inlet and an air outlet.

The air inlet may be any suitable air inlet.

In some embodiments, the device comprises the air inlet. In some embodiments, the cartridge comprises the air inlet. In some preferred embodiments, the air inlet is defined between the cartridge and the device when the portion of the cartridge is received in the device cavity.

The air inlet may comprise a single air inlet. The air inlet may comprise a plurality of air inlets. The air inlet may comprise any suitable number of air inlets. For example, the air inlet may comprise one, two, three, four, five or six air inlets.

The air outlet may be any suitable air outlet.

In some embodiments, the device comprises the air outlet. In some preferred embodiments, the cartridge comprises the air outlet.

The air outlet may comprise a single air outlet. The air outlet may comprise a plurality of air outlets. The air outlet may comprise any suitable number of air outlets. For example, the air outlet may comprise one, two, three, four, five or six air outlets.

In some embodiments, the device comprises a connection end. The device cavity may be arranged at the connection end of the device.

In some embodiments, the cartridge comprises: a mouth end; and a connection end, opposite the mouth end. The connection end may be configured to be received by the device cavity. The connection end may be the portion of the cartridge that is received by the device cavity. In some preferred embodiments, the air outlet of the airflow path is arranged at a mouth end of the cartridge. The mouth end of the cartridge may be configured for a user to draw on the mouth end to inhale an aerosol generated by the aerosol-generating system.

A portion of the connection end of the cartridge may form a portion of the airflow cavity when the portion of the cartridge is received in the device cavity. A portion of a surface of the connection end of the cartridge may form at least a portion of a surface of the airflow cavity when the portion of the cartridge is received in the device cavity.

Where the aerosol-generating system comprises a flow restriction, and the flow restriction is defined between the device and the cartridge, a portion of the connection end of the cartridge may form a portion of the flow restriction when the portion of the cartridge is received in the device cavity. A portion of a surface of the connection end of the cartridge may form at least a portion of a surface of the flow restriction when the portion of the cartridge is received in the device cavity.

In some preferred embodiments, the portion of the airflow path between the air inlet and the airflow cavity is defined between the cartridge housing and the device housing. In some of these preferred embodiments, the portion of the airflow path between the air inlet and the airflow cavity extends along the length of the device cavity. Advantageously, arranging a portion of the airflow path between the device cavity and an outer surface of the device housing may lower the temperature of the outer surface of the device housing when the aerosol-generating system is in use due to the airflow in that portion of the airflow path insulating the device cavity from the external surface of the device housing. Advantageously, arranging a portion of the airflow path between the device housing and the cartridge housing may help to prevent condensation on an external surface of the device housing, which may result from a difference in temperature between the external surface of the device housing and the external environment by insulating the external surface of the device housing from the heat generated around the device cavity by the generation of aerosol.

The device comprises a device cavity. The device cavity is configured to receive a portion of the cartridge. The device cavity may have any suitable size and shape.

In some embodiments, the device cavity comprises: an open end to enable the portion of the cartridge to be received in the device cavity; and a substantially closed end, opposite the open end.

The device cavity may meet the airflow path at or around the substantially closed end. The airflow path may meet the device cavity at or around the substantially closed end of the device cavity. In other words, the device cavity may intersect the airflow path at or around the substantially closed end. A portion of the device cavity at or around the substantially closed end may form a portion of the airflow cavity when the portion of the cartridge is received in the device cavity. A portion of a surface of the device cavity at or around the substantially closed end of the device cavity may form at least a portion of a surface of the airflow cavity when the portion of the cartridge is received in the device cavity.

Where the aerosol-generating system comprises a flow restriction, and the flow restriction is defined between the device and the cartridge, a portion of the device cavity at or around the substantially closed end may form a portion of the flow restriction when the portion of the cartridge is received in the device cavity. A portion of a surface of the device cavity at or around the substantially closed end may form at least a portion of a surface of the flow restriction when the portion of the cartridge is received in the device cavity.

Where the aerosol-generating system comprises a flow restriction, the flow restriction may be arranged at or around the substantially closed end of the device cavity. Where the device comprises the flow restriction, the flow restriction may be arranged below or beneath the substantially closed end of the device cavity. Where the device comprises the flow restriction, the flow restriction may be arranged adjacent or immediately adjacent the device cavity. The flow restriction may be arranged adjacent or immediately adjacent the substantially closed end of the device cavity.

The pressure sensor may be arranged at any suitable location in the device. The pressure sensor may be arranged at or around the substantially closed end of the device. In some embodiments, a portion of a surface of the pressure sensor may form a portion of a surface of the device cavity.

In some preferred embodiments, the pressure sensor is located in a pressure sensor cavity in the device. The pressure sensor cavity may be arranged below or beneath the device cavity. The pressure sensor cavity may be arranged below or beneath the substantially closed end of the device cavity.

The pressure sensor cavity may have any suitable shape or size.

In some preferred embodiments, an additional airflow path is provided between the airflow cavity and the pressure sensor cavity. The additional airflow path may enable air to flow between the airflow cavity and the pressure sensor cavity.

In some preferred embodiments, the cartridge comprises two parts, a first part and a second part, wherein the second part is movable relative to the first part. In some of these preferred embodiments, the first part comprises the liquid reservoir, and the second part comprises the heating element. The first part and the second part may be movable between a storage position and a use position. In the storage position, the liquid reservoir in the first part of the cartridge may be isolated from the heating element in the second part of the cartridge. Isolating the liquid reservoir from the heating element may prevent liquid held in the liquid reservoir from reaching the heating element. Preventing liquid from reaching the heating element may reduce the likelihood of liquid held in the reservoir from leaking out of the cartridge. In the use position, a liquid path may be provided from the liquid reservoir to the heating element. Providing a liquid path from the liquid reservoir to the heating element may enable liquid from the liquid reservoir to reach the heating element. In the use position, the heating element may be positioned to heat liquid from the liquid reservoir to generate an aerosol.

The cartridge may be configured to prevent liquid held in the liquid reservoir from reaching the heating element when the first part and the second part are in the storage position in any suitable manner. For example, a frangible seal may be arranged in the liquid path between the liquid reservoir and the heating element to prevent liquid held in the liquid reservoir from passing through the liquid path to reach the heating element when the first part and the second part are in the storage position, and the frangible seal may be broken to enable liquid to pass from the liquid reservoir through the liquid path to reach the heating element when the second part is moved relative to the first part from the storage position to the use position. In some preferred embodiments, the second part comprises stops that cooperate with the first part to prevent liquid in the liquid reservoir from passing through the liquid path to reach the heating element when the first part and the second part are in the storage position, and the stops move with the second part relative to the first part to a position in which liquid held in the liquid reservoir is able to pass through the liquid path to reach the heating element when the second part is moved from the storage position to the use position. Such an arrangement comprising movable stops enables the cartridge to be repeatedly moved between the use position and the storage position and continue to prevent liquid held in the liquid reservoir from passing through the liquid path to the heating element when the first part and the second part are in the storage position, since the stops are not broken during movement between the storage position and the use position.

The first part and the second part may be configured to be biased to the storage position. For example, a resilient element, such as a spring, may be provided in the cartridge to urge the second part relative to the first part from the use position to the storage position. Advantageously, biasing the first part and the second part to the storage position, rather than the use position, may reduce the likelihood of leakage of liquid held in the liquid reservoir when the cartridge is not received in the device cavity.

The first part and the second part of the cartridge may be movable between the storage position and the use position in any suitable manner. In some preferred embodiments, the second part is slidable relative to the first part.

In some particularly preferred embodiments, the cartridge housing comprises the first part and the second part. In these embodiments, the first part is a first cartridge housing part and the second part is a second cartridge housing part.

In some embodiments, and particularly in some embodiments in which the cartridge comprises a first part and a second part movable relative to the first part, the device comprises a pushing element. The pushing element may be configured to move either the first part relative to the second part or the second part relative to the first part, when the portion of the cartridge is received in the device cavity. The pushing element may be configured to move the first part and the second part from the storage position to the use position when the portion of the cartridge is received in the device cavity. The pushing element may be configured to engage with the first part when the portion of the cartridge is received in the device cavity. The pushing element may be configured to contact the first part when the portion of the cartridge is received in the device cavity. The pushing element may be configured to contact the second part when the portion of the cartridge is received in the device cavity. Advantageously, providing the device with a pushing element configured to move the first part and the second part from the storage position to the use position when the portion of the cartridge is received in the device cavity may help to reduce the likelihood of leakage of liquid held in the liquid reservoir when the cartridge is not received in the device cavity and minimise any additional actions required to be performed by a user to prepare the aerosol-generating system for use. Providing the device with a pushing element minimises the additional actions required to be performed by a user to prepare the aerosol-generating system for use by enabling the cartridge to be moved from the storage position to the use position during insertion of the portion of the cartridge in the device cavity.

In some embodiments, the device housing comprises the pushing element.

The pushing element may extend into the device cavity. In some preferred embodiments, the pushing element extends into the device cavity from the substantially closed end of the device cavity.

In some preferred embodiments, at least a portion of a surface of the pushing element defines at least a portion of a surface of the airflow cavity when the portion of the cartridge is received in the device cavity.

In some embodiments comprising a pressure sensor cavity, the pressure sensor cavity is at least partially arranged in the pushing element. In these embodiments, at least a portion of the pressure sensor may be arranged in the pushing element.

In some embodiments comprising an additional airflow path between the airflow cavity and the pressure sensor cavity, at least a portion of the additional airflow path may be arranged in the pushing element.

In some embodiments, a sealing element is arranged at the substantially closed end of the device cavity. The sealing element may be arranged to not substantially obstruct the airflow path. The sealing element may substantially cover the substantially closed end of the device cavity without obstructing the airflow path. Advantageously, the sealing element may help to ensure that air flows through the airflow path, without escaping through other gaps or spaces in the device housing. Particularly advantageously, where a flow restriction is provided in the airflow path, the sealing element may help to ensure that air flows through the flow restriction, rather than through other gaps or spaces in the device housing. The sealing element may be a resilient element. The sealing element may be an elastomeric element. The sealing element may provide a liquid-tight seal, or preferably an air-tight seal, over a portion of the airflow path. Providing an air-tight seal, which may be referred to as a hermetic seal, may ensure that the airflow through the portion of the airflow path comprising the sealing element is closely controlled, resulting in a predictable and consistent resistance to draw through the airflow path. In some embodiments, the sealing element may be provided at the flow restriction. The device may further comprise a controller. The controller may be configured to receive pressure measurements from the pressure sensor. The controller may be configured to receive pressure measurement information from the pressure sensor. The pressure measurements may comprise pressure measurement information. The pressure measurement information may comprise any information obtainable from a pressure sensor. The pressure measurement information comprises information on the pressure at the airflow cavity.

The controller may be configured to determine when a user is taking a puff on the aerosolgenerating system based on pressure measurements from the pressure sensor. The controller may be configured to determine when a user is taking a puff on the aerosol-generating system based on pressure measurement information received from the pressure sensor.

The controller may be configured to receive pressure measurements at regular intervals The controller may be configured to receive pressure measurement information from the pressure sensor at regular intervals. The controller may be configured to regularly receive pressure measurement information from the pressure sensor. The controller may be configured to continuously receive pressure measurement information from the pressure sensor. The controller may be configured to receive pressure measurements at any suitable sampling rate. The controller may be configured to receive pressure measurements and pressure measurement information at any suitable sampling rate. For example, the controller may be configured to receive pressure measurements and pressure measurement information at a sampling rate of at least 50 Hertz, at least 60 Hertz, at least 65 Hertz. In some preferred embodiments, the controller is configured to receive pressure measurements and pressure measurement information at a sampling rate of about 75 Hertz.

The controller may be configured to determine an average pressure from pressure measurement information received from the pressure sensor over time. The average pressure may be a moving average. In other words, the average pressure may be updated for each subsequent measurement of pressure. The moving average pressure may be a mean pressure, a median pressure, or a mode pressure. The moving average pressure may be determined from a plurality of pressure measurements received from the pressure sensor. The moving average pressure may be determined from a plurality of consecutive pressure measurements received from the pressure sensor. The moving average pressure may be determined from any suitable number of pressure measurements. For example, the moving average may be determined from at least two, three, four, five, six, seven, eight, nine or ten pressure measurements. The moving average pressure may be determined from between 2 and 100 pressure measurements, between 2 and 75 pressure measurements, or between 2 and 40 pressure measurements.

Determining a moving average pressure from a plurality of pressure measurements taken over time may provide the controller with a baseline pressure against which subsequent pressure measurements may be compared. Comparing subsequent pressure measurements to the determined average pressure measurement may enable the controller to determine larger than expected changes in the measured pressure. Larger than expected changes in pressure in the airflow cavity may indicate that a user is taking a puff on the aerosol-generating system.

The controller may be configured to determine when a user is taking a puff on the aerosolgenerating system based on pressure measurement information received from the pressure sensor. The controller may be configured to detect a puff on the aerosol-generating system based on pressure measurement information received from the pressure sensor. The controller may be configured to determine when a user is taking a puff on the aerosol-generating system based on a comparison of pressure measurement information received from the pressure sensor to a threshold value. The controller may be configured to determine when a user is taking a puff on the aerosolgenerating system based on a comparison of pressure measurement information received from the pressure sensor to a determined moving average pressure from earlier pressure measurement information received from the pressure sensor.

In some preferred embodiments, the controller may be configured to determine a moving average pressure from pressure measurement information received from the pressure sensor over time, compare a subsequent pressure measurement to the determined moving average pressure, and determine when a user is taking a puff on the aerosol-generating system based on the comparison. When a puff is detected, the moving average may be held constant, or not updated, until it is determined that the user has stopped taking a puff on the aerosol-generating system. Holding the moving average pressure constant while a user is taking a puff on the aerosol-generating system may enable the moving average pressure to be used as a baseline pressure against which pressure measurements taking during a puff may be compared. Holding the moving average pressure constant during a puff may enable the end of a puff to be determined.

Advantageously, determining when a user is taking a puff on the aerosol-generating system based on a moving average pressure, and comparing subsequent pressure measurements to the moving average pressure, may reduce the likelihood of false determinations of puffs resulting from changes in atmospheric pressure, such as changes in altitude, compared to comparisons of pressure measurements with static thresholds. This is because the determined moving average is able to change with gradual changes in external pressure, In particular, comparing pressure measurements to a determined moving average pressure, rather than a static threshold value, is advantageous when a single pressure sensor is provided, sensing the absolute pressure in the airflow cavity. Where a gauge pressure sensor, differential pressure sensor, or two or more pressure sensors are provided, and a differential pressure is measured or determined, there is less benefit to comparing differential pressure measurements or pressure differences to a determined moving average, rather than a static threshold value. This is because differential pressure measurements or pressure differences are less affected by changes is external or atmospheric pressure than individual, absolute pressure measurements.

The controller may be configured to determine the end of a puff on the aerosol-generating system based on pressure measurement information received from the pressure sensor. The controller may be configured to determine when a user stops taking a puff on the aerosol-generating system based on pressure measurement information received from the pressure sensor. The controller may be configured to determine when a user stops taking a puff on the aerosol-generating system based on a comparison of pressure measurement information received from the pressure sensor to a threshold value. The controller may be configured to determine a moving average pressure from pressure measurement information received from the pressure sensor over time, compare a subsequent pressure measurement to the determined moving average pressure, determine when a user is taking a puff on the aerosol-generating system based on the comparison, and determine when a user stops taking a puff on the aerosol-generating system based on a comparison of a further subsequent pressure measurement to the previously determined moving average. In other words, the determined moving average pressure used in the comparison with the subsequent pressure measurement when the puff was detected may be stored by the controller and used as a baseline or a threshold against which further subsequent pressure measurements are compared to determine when the user stops taking a puff on the aerosol-generating system.

The controller may be configured to determine a puff duration based on pressure measurement information received from the pressure sensor. The controller may be configured to determine a puff duration based on the difference in time between when it is first determined that a user is taking a puff on the aerosol-generating system and when it is next determined that the user has stopped taking a puff on the aerosol-generating system.

Atypical puff duration may range from between about 1 second and about eight seconds, and more typically between about 3 seconds and about six seconds.

The cartridge comprises a heating element. The heating element is configured to heat a liquid aerosol-forming substrate held in the liquid reservoir to generate an aerosol.

Where the device comprises a controller, the controller may be configured to control a supply of power to the heating element. The controller may be configured to control a supply of power to the heating element based on pressure measurements received from the pressure sensor. In some embodiments where the controller is configured to determine when a user is taking a puff on the aerosol-generating system based on pressure measurements received from the pressure sensor, the controller may be configured to control the supply of power to the heating element based on when it is detected that a user is taking a puff on the aerosol-generating system. In some embodiments, the heating element comprises a resistive heating element.

The resistive heating element may be formed from any suitable material.

The resistive heating element may be formed from an electrically conductive material. As used herein, “electrically conductive” refers to a material having a volume resistivity at 20 degrees Celsius (°C) of less than about 1 x 10^-5 ohm-metres (Dm), typically between about 1 x 10^-5 ohm-metres (Qm) and about 1 x 10^-9 ohm-metres (Qm).

The resistive heating element may be formed from a thermally conductive material. As used herein, “thermally conductive” refers to a material having a bulk thermal conductivity of at least about 10 Watts per metre Kelvin (mW/(m K)) at 23 degrees Celsius (°C) and a relative humidity of 50 percent as measured using the modified transient plane source (MTPS) method.

The resistive heating element may be formed from at least one of: graphite, molybdenum, silicon carbide, a metal, stainless steel, niobium, aluminium, nickel, titanium, and composites of metallic materials.

In some preferred embodiments, the heating element comprises a susceptor element.

As used herein, “susceptor element” refers to an element that is heatable by penetration with a varying magnetic field. A susceptor element is typically heatable by at least one of Joule heating through induction of eddy currents in the susceptor element, and hysteresis losses.

Where the heating element comprises a susceptor element, the aerosol-generating system comprises an inductive heating assembly comprising an inductor coil and the heating element. The device comprises the inductor coil, and the cartridge comprises the susceptor element.

Where the device comprises an inductor coil, the device may be configured to supply a varying current to the inductor coil. When the inductor coil is supplied with a varying current, the inductor coil is configured to generate a varying magnetic field. When the portion of the cartridge is received in the device cavity, the inductor coil and susceptor element are arranged such that the varying magnetic field generated by the inductor coil when supplied with a varying current penetrates the susceptor element.

The inductor coil may be arranged at any suitable location. The inductor coil may be arranged to generate a varying magnetic field in the device cavity. The inductor coil may be located in or around the device cavity. The inductor coil may circumscribe the device cavity.

As used herein, “varying current” refers to a current that varies with time. An inductor coil generates a varying magnetic field when a varying electric current is supplied to the inductor coil. The term “varying current” is intended to include alternating currents. Where the varying current is an alternating current, the alternating current supplied to the inductor coil generates an alternating magnetic field. The varying current may be an alternating current. As used herein, “alternating current” refers to a current that periodically reverses direction. The alternating current may have any suitable frequency. Suitable frequencies for the alternating current may be between 100 kilohertz (kHz) and 30 megahertz (MHz). Where the at least one inductor coil is a tubular inductor coil, the alternating current may have a frequency of between 500 kilohertz (kHz) and 30 megahertz (MHz). Where the at least one inductor coil is a flat coil, the alternating current may have a frequency of be-tween 100 kilohertz (kHz), and 1 megahertz (MHz).

The inductor coil may have any suitable form. The inductor coil may be a tubular inductor coil. The inductor coil may be a planar inductor coil. The inductor coil may be a flat inductor coil. Preferably, the inductor coil is a tubular coil that circumscribes the device cavity.

The inductor coil may have any suitable number of turns.

The inductor coil may be formed from any suitable material. The inductor coil may be formed from at least one of: silver, gold, aluminium, brass, zinc, iron, nickel, and alloys of thereof, and electrically conductive ceramics, such as yttrium-doped zirconia, indium tin oxide, and yttrium doped titanate.

When the portion of the cartridge is received in the device cavity, the susceptor element of the cartridge may be arranged to be penetrated by the varying magnetic field generated by the inductor coil when the varying current is supplied to the inductor coil.

The susceptor element may be formed from any suitable material. Preferably, the susceptor element comprises a magnetic material that is heatable by penetration with a varying magnetic field. The magnetic material may be a ferromagnetic material, such as ferrite, ferritic iron, a ferromagnetic alloy, a ferromagnetic steel, or a ferromagnetic stainless steel such as SAE 400 series stainless steels, SAE type 409, 410, 420 or 430 stainless steels.

As used herein, “magnetic material” refers to a material which is able to interact with a magnetic field, including both paramagnetic and ferromagnetic materials.

In some preferred embodiments, the susceptor element comprises at least about 5 percent, or at least about 20 percent, or at least about 50 percent, or at least about 90 percent of ferromagnetic or paramagnetic materials on a dry weight basis.

The susceptor element shape may be different to the inductor coil shape. Preferably, the susceptor element shape is substantially the same as the inductor coil shape.

The inductor coil size may be different to the inductor coil size. Preferably, the susceptor element size is substantially the same as the inductor coil size.

In some preferred embodiments, the device comprises a controller. The controller may be configured to control a supply of power to the heating element. Where the aerosol-generating system comprises an inductive heating arrangement, and the device comprises an inductor coil of the inductive heating arrangement, the controller may be configured to control a supply of power to the inductor coil.

The controller may be configured to supply current to the heating element or the inductor coil continuously following activation of the aerosol-generating system. The controller may be configured to supply current to the heating element or the inductor coil intermittently, such as on a puff by puff basis.

The controller may comprise a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application specific integrated chip (ASIC) or other electronic circuitry capable of providing control.

The controller may be a part of control circuitry of the device. The control circuitry may comprise further electronic components. The control circuitry may advantageously comprise DC/ AC inverter, which may comprise a Class-D or Class-E power amplifier.

The device may further comprise a power supply. The power supply may be configured to supply power to the heating element. The controller may be configured to control the supply of power from the power supply to the heating element. Where the aerosol-generating system comprises an inductive heating arrangement, the power supply may be configured to supply power to the inductor coil of the inductive heating arrangement. The controller may be configured to control the supply of power from the power supply to the inductor coil.

The power supply may be a DC power supply. The power supply may comprise at least one of a battery and a capacitor. The power supply may be a battery. The battery may be any suitable type of battery. The battery may be a Lithium based battery, for example a Lithium-Cobalt, a Lithium- Iron-Phosphate, a Lithium Titanate or a Lithium-Polymer battery. The battery may be a Nickel metal hydride battery or a Nickel cadmium battery. The power supply may be another form of charge storage device, such as a capacitor. In one embodiment, the power supply is a DC power supply having a DC supply voltage in the range of about 2.5 Volts to about 4.5 Volts and a DC supply current in the range of about 1 Amp to about 10 Amps (corresponding to a DC power supply in the range of about 2.5 Watts to about 45 Watts).

Where the aerosol-generating system comprises an inductive heating arrangement, and the device comprises an inductor coil of the inductive heating arrangement, the power supply and the controller may be configured to supply an alternating current to the inductor coil.

The power supply and the controller may be configured to operate at high frequency. Where the device comprises an inductor coil of an inductive heating arrangement, the power supply and the controller may be configured to supply a high frequency oscillating current to the inductor coil. As used herein, the term “high frequency oscillating current” means an oscillating current having a frequency of between about 500 kilohertz and about 30 megahertz. The high frequency oscillating current may have a frequency of from about 1 megahertz to about 30 megahertz, preferably from about 1 megahertz to about 10 megahertz and more preferably from about 5 megahertz to about 8 megahertz.

Where the controller is configured to control the supply of power to the heating element or to the inductor coil of the inductive heating arrangement, the controller may be configured to control the supply of power to the heating element in any suitable way. Preferably, the controller is configured to control the supply of power to the heating element in pulses. Where the controller is configured to control the supply of power to the heating element in pulses, the controller may be configured to control the supply of power to the heating element by pulse width modulation.

The controller may be configured to control the supply of power to the heating element based on pressure measurements received from the pressure sensor.

The cartridge comprises a liquid reservoir configured to hold a liquid aerosol-forming substrate. The liquid aerosol-forming substrate may comprise any suitable components.

The liquid aerosol-forming substrate may comprise nicotine. The nicotine containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may comprise plant-based material. The liquid aerosol-forming substrate may comprise tobacco. The liquid aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds, which are released from the aerosol-forming substrate upon heating. The liquid aerosol-forming substrate may comprise homogenised tobacco material. The liquid aerosol-forming substrate may comprise a non-tobacco-containing material. The liquid aerosolforming substrate may comprise homogenised plant-based material.

The liquid aerosol-forming substrate may comprise one or more aerosol-formers. An aerosolformer is any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol and that is substantially resistant to thermal degradation at the temperature of operation of the system. Examples of suitable aerosol formers include glycerine and propylene glycol. Suitable aerosol-formers are well known in the art and include, but are not limited to: polyhydric alcohols, such as 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. The liquid aerosol-forming substrate may comprise water, solvents, ethanol, plant extracts and natural or artificial flavours. The liquid aerosol-forming substrate may comprise nicotine and at least one aerosol former. The aerosol former may be glycerine or propylene glycol. The aerosol former may comprise both glycerine and propylene glycol. The liquid aerosol-forming substrate may have a nicotine concentration of between about 0.5% and about 10%, for example about 2%. The aerosol-generating system may be a handheld aerosol-generating system. The aerosolgenerating system may be a handheld aerosol-generating system configured to allow a user to draw on a mouthpiece end to draw an aerosol through the air outlet. The aerosol-generating system may have a size comparable to a conventional cigar or cigarette. The aerosol-generating system may have a total length between about 25 mm and about 150 mm. The aerosol-generating system may have an external width or diameter between about 5 mm and about 30mm.

The invention is defined in the claims. However, below there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

1 . An aerosol-generating system comprising: a cartridge comprising: a cartridge housing; a liquid reservoir configured to hold a liquid aerosol-forming substrate; and a heating element configured to heat liquid from the liquid reservoir; and a device comprising: a device housing defining a device cavity configured to receive a portion of the cartridge; wherein: when the portion of the cartridge is received in the device cavity, the aerosol-generating system comprises an airflow path defined between an air inlet and an air outlet; when the portion of the cartridge is received in the device cavity, an airflow cavity is located in the airflow path, the airflow cavity being defined between the cartridge housing and the device housing; and the device comprises a pressure sensor arranged to detect the pressure in the airflow cavity.

2. An aerosol-generating system according to example 1 , wherein the pressure in the airflow path is at a minimum in the airflow cavity when air is drawn through the airflow path between the air inlet and the air outlet.

3. An aerosol-generating system according to example 1 or example 2, wherein a flow restriction is arranged in the airflow path between the air inlet and the airflow cavity.

4. An aerosol-generating system according to example 3, wherein the flow restriction is arranged immediately upstream of the airflow cavity.

5. An aerosol-generating system according to example 3 or example 4, wherein the flow restriction is a portion of the airflow path having a width that is smaller than the width of the airflow cavity. 6. An aerosol-generating system according to any one of examples 3 to 5, wherein the flow restriction is a portion of the airflow path having the smallest width of any portion of the airflow path.

7. An aerosol-generating system according to any one of examples 3 to 6, wherein the flow restriction is a portion of the airflow path having a cross-sectional area that is smaller than the cross-sectional area of the airflow cavity.

8. An aerosol-generating system according to any one of examples 3 to 7, wherein the flow restriction is a portion of the airflow path having the smallest cross-sectional area of any portion of the airflow path.

9. An aerosol-generating system according to any one of examples 3 to 8, wherein the aerosol-generating device comprises the flow restriction.

10. An aerosol-generating system according to any one of examples 3 to 8, wherein when the portion of the cartridge is received in the device cavity, the flow restriction is defined between the cartridge housing and the device housing.

11 . An aerosol-generating system according to example 10, wherein at least a portion of a surface of the cartridge housing defines at least a portion of a surface of the flow restriction.

12. An aerosol-generating system according to example 10 or example 11 , wherein at least a portion of a surface of the device housing defines at least a portion of a surface of the flow restriction.

13. An aerosol-generating system according to any one of examples 3 to 12, wherein the flow restriction has a width of between 0.15 millimetres and 0.8 millimetres.

14. An aerosol-generating system according to any one of examples 3 to 13, wherein the flow restriction has a depth of between 0.3 millimetres and 1.2 millimetres.

15. An aerosol-generating system according to any one of examples 3 to 14, wherein the flow restriction has a length of between 1 millimetres and 2 millimetres.

16. An aerosol-generating system according to any one of examples 3 to 14, wherein the flow restriction has a cross-sectional area of between 0.045 millimetres squared and 1 millimetre squared.

17. An aerosol-generating system according to any one of examples 1 to 16, wherein at least a portion of a surface of the cartridge housing defines at least a portion of a surface of the airflow cavity.

18. An aerosol-generating system according to any one of examples 1 to 17, wherein at least a portion of a surface of the device housing defines at least a portion of a surface of the airflow cavity. 19. An aerosol-generating system according to any one of examples 1 to 18, wherein when a portion of the cartridge is received in the device cavity, the air inlet of the airflow path is defined between the cartridge and the device.

20. An aerosol-generating system according to any one of examples 1 to 19, wherein the cartridge comprises: a mouth end; and connection end, opposite the mouth end, wherein the connection end is configured to be received by the device cavity.

21 . An aerosol-generating system according to example 20, wherein the air outlet of the airflow path is arranged at a mouth end of the cartridge.

22. An aerosol-generating system according to example 20 or example 21 , wherein the mouth end of the cartridge is configured for a user to draw on the mouth end to inhale an aerosol generated by the aerosol-generating system.

23. An aerosol-generating system according to any one of examples 1 to 22, wherein the pressure sensor is located in a pressure sensor cavity in the device.

24. An aerosol-generating system according to example 23, wherein an additional airflow path is provided between the airflow cavity and the puff sensor cavity to enable air to flow between the airflow cavity and the puff sensor cavity.

25. An aerosol-generating system according to any one of examples 1 to 24, wherein the device cavity comprises: an open end to enable the portion of the cartridge to be received in the device cavity; and a substantially closed end, opposite the open end.

26. An aerosol-generating system according to example 25, wherein the device cavity meets the airflow path at the substantially closed end.

27. An aerosol-generating system according to example 25 or example 26, wherein the flow restriction is arranged at or around the substantially closed end of the device cavity.

28. An aerosol-generating system according to any one of examples 25 to 27, wherein a sealing element is arranged at the substantially closed end of the device cavity, and wherein the sealing element does not substantially obstruct the airflow path.

29. An aerosol-generating system according to any one of examples 25 to 28, wherein the device housing comprises a pushing element, and wherein the pushing element extends into the device cavity from the substantially closed end.

30. An aerosol-generating system according to example 29, wherein the cartridge housing comprises two parts, a first cartridge housing part, and a second cartridge housing part, wherein the second cartridge housing part is movable relative to the first cartridge housing part, and wherein the pushing element is arranged to contact the second cartridge housing part when the portion of the cartridge is received in the device cavity and move the second cartridge housing part relative to the first cartridge housing part.

31 . An aerosol-generating system according to example 29 or example 30, wherein at least a portion of a surface of the pushing element defines at least a portion of a surface of the airflow cavity when the portion of the cartridge is received in the device cavity.

32. An aerosol-generating system according to any one of examples 1 to 31 , wherein the aerosol-generating system further comprises an inductive heating assembly comprising an inductor coil and the heating element, wherein the device comprises the inductor coil, and wherein the heating element comprises a susceptor element.

33. An aerosol-generating system according to example 32, wherein the device is configured to supply a varying current to the inductor coil, wherein the inductor coil is configured to generate an alternating magnetic field when supplied with a varying current, and wherein the inductor coil and susceptor element are arranged such that the varying magnetic field penetrates the susceptor element when the portion of the cartridge is received in the device cavity.

34. An aerosol-generating system according to example 32 or example 33, wherein the inductor coil circumscribes the device cavity.

35. An aerosol-generating system according to any one of examples 1 to 34, wherein the device further comprises a power supply configured to supply power to the heating element when a portion of the cartridge is received in the device cavity,

36. An aerosol-generating system according to any one of examples 32 to 34, wherein the device further comprises a power supply and a controller configured to supply a varying current to the inductor coil.

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

Figure 1 shows a schematic illustration of a cartridge of an aerosol-generating system according to an embodiment of the disclosure;

Figure 2 shows a schematic illustration of a device of an aerosol-generating system according to an embodiment of the disclosure;

Figure 3 shows a schematic illustration of an aerosol-generating system according to an embodiment of the present disclosure, the aerosol-generating system comprising the cartridge of Figure 1 and the device of Figure 2;

Figure 4 shows a portion of the aerosol-generating system of Figure 3, in which the cartridge is not received in the device cavity of the device; Figure 5 shows a portion of the aerosol-generating system of Figure 3, in which the cartridge is received in the device cavity of the device;

Figure 6 shows a portion of the aerosol-generating system of Figure 3, in which the cartridge is received in the device cavity;

Figure 7 shows a cross-sectional view of the aerosol-generating system of Figure 6;

Figure 8 shows a portion of the aerosol-generating system of Figure 3, in which the cartridge is received in the device cavity of the device and air is being drawn through the aerosol-generating system;

Figure 9 shows a portion of an aerosol-generating system according to another embodiment of the present disclosure, in which the cartridge is received in the device cavity of the device; and

Figure 10 shows a plan view of the device of the aerosol-generating system of Figure 9 from the open end of the device cavity towards the substantially closed end;

Figure 11 shows a portion of an aerosol-generating system according to another embodiment of the present disclosure, in which the cartridge is received in the device cavity of the device and air is being drawn through the aerosol-generating system; and

Figure 12 shows a portion of the aerosol-generating system of Figure 11 .

A first example of an aerosol-generating system 10 according to the present disclosure is shown in Figures 1 -8. The aerosol-generating system 10 comprises a cartridge 12 and a device 14.

The cartridge 12 is shown in Figure 1 . The cartridge 12 comprises a cartridge housing including a first cartridge housing part 16 and a second cartridge housing part 18. The second cartridge housing part 18 is substantially tubular, defining an inner passage 19. The first cartridge housing part 16 is also substantially tubular, with a larger width than the second cartridge housing part 18, and defines an inner passage with a larger width than the second cartridge housing part 18. The second cartridge housing part 18 is received within the inner passage of the first cartridge housing part 16, such that the second cartridge housing part 18 is surrounded by the first cartridge housing part 16 with a longitudinal axis of the second housing portion 18 aligned with a longitudinal axis of the first cartridge housing part 16.. When the second cartridge housing part 18 is received within the inner passage of the first cartridge housing part 16, the second cartridge housing part 18 is movable relative to the first cartridge housing part 16 between a storage position, as shown in Figure 1 , and a use position, as shown in Figure 3. In this embodiment, the second cartridge housing part 18 is slidable relative to the first cartridge housing part 16 along the aligned longitudinal axes of the first and second cartridge housing parts 16, 18.

The cartridge 12 comprises a mouth end 20 and a connection end 21 . At the mouth end of the first cartridge housing part 16, the first cartridge housing part 16 comprises an air outlet 22, having a width that is slightly smaller than the width of the inner passage 19 of the second cartridge housing part 18. An inner tube 23 extends from the air outlet 22 of the first cartridge housing part 16 along the longitudinal axis of the first cartridge housing part 16. The second cartridge housing part 18 is received over the inner tube 23 of the first cartridge housing part 16 at the mouth end 20. The inner passage 19 of the second cartridge housing part 18 is slidable over the inner tube 23, along the aligned longitudinal axes of the first and second cartridge housing parts 16, 18 to move the second cartridge housing part 18 between the storage position and the use position. An O-ring 24 is provided between the inner tube 23 of the first cartridge housing part and the second cartridge housing part 18 to prevent liquid from flowing through the gap between the inner tube 29 and the second cartridge housing part 18. Also at the mouth end of the first cartridge housing part 16, the first cartridge housing part 16 has a region with a wider external diameter than the connection end of the first cartridge housing part 16.

A liquid reservoir 25 is defined in the region between the region with the wider diameter of the first cartridge housing part 16 and the second cartridge housing part 18 at the mouth end of the cartridge 12. The liquid reservoir 25 is configured to hold a liquid aerosol-forming substrate 26. Liquid aerosol-forming substrate 26 is prevented from flowing from the liquid reservoir 25 into the inner passage 19 of the second cartridge housing part 18 at the mouth end by the O-ring 24. The second cartridge housing part 18 further comprises an annular first stop 27 extending radially outwardly from the second cartridge housing part 18 at a distance of about the length of the inner tube 23 of the first cartridge housing part 16 from the mouth end of the second cartridge housing part 18. The first stop 27 extends radially outwardly from the second cartridge housing part at a distance to contact the inner surface of the inner passage of the first cartridge housing part 16, below the wider region at the mouth end. When the cartridge 12 is in the storage position, the first stop 27 of the second cartridge housing part 18 contacts the inner surface of the first cartridge housing part 16 and prevents liquid aerosol-forming substrate 26 from flowing out of the liquid reservoir 25 beyond the first stop 27 to the connection end 21 of the cartridge 12.

When the cartridge is moved to the use position, as shown in Figure 3, the second cartridge housing part 18 is slid along the aligned longitudinal axes towards the mouth end of the first cartridge housing part 16, until the first stop 27 reaches the wider region at the mouth end of the second cartridge housing part 18. When the first stop 27 reaches the wider region at the mouth end of the second cartridge housing part 18, the first stop 27 no longer contacts the inner surface of the first cartridge housing part 16, and a gap is provided between the first cartridge housing part 16 and the second cartridge housing part 18, such that liquid aerosol-forming substrate 26 in the liquid reservoir 25 is able to flow out of the liquid reservoir 25 into the gap between the first cartridge housing part 16 and the second cartridge housing part 18 at the connection end of the second cartridge housing part 18. A second stop 28 is provided at the connection end of the second cartridge housing part 18. The second stop 28 is substantially similar to the first stop 27, and contacts the inner surface of the inner passage of the first cartridge housing part 16, below the wider region at the mouth end, to stop liquid from flowing beyond the connection end of the second cartridge housing part 18 when the cartridge 12 is in the use position. An additional O-ring seal 29 is also provided at the second stop 28 to improve the seal between the second stop 28 and the inner surface of the inner passage of the first cartridge housing part 16.

The cartridge 12 further comprises a heater assembly 30. The heater assembly 30 is generally in the form of a flat, planar sheet. The heater assembly 20 comprises a heating element 31 , in the form of a susceptor element, and a wicking element 32. In this embodiment, the susceptor element 31 comprises a sintered mesh formed from ferritic stainless steel filaments and austenitic stainless steel filaments. The wicking element 32 comprises a porous body of rayon filaments.

The heater assembly 30 is held in the second cartridge housing portion 18, towards the connection end and below the first stop 27. The susceptor element 31 is arranged to extend across the inner passage 19 of the second cartridge housing portion 18, and the wicking element 32 is arranged to extend outwardly beyond the susceptor element 31 at opposite sides of the susceptor element 31 , and extends through the second cartridge housing part 18, radially outward at each side by a distance slightly less than the first and second stops 27, 28.

When the cartridge 12 is in the use position, as shown in Figure 3, and liquid aerosol-forming substrate 26 from the liquid reservoir 25 flows into the gap between the first cartridge housing part 16 and the second cartridge housing part 18 at the connection end, the liquid aerosol-forming substrate 26 in the gap comes into contact with the wicking element 32 of the heater assembly, and is drawn by the wicking element onto the susceptor element 31 .

At the connection end 21 of the cartridge, the second cartridge housing portion 18 comprises a base 33, which substantially closes the connection end of the second cartridge housing portion 18, and the first cartridge housing portion 16 comprises and inwardly extending flange 34, which extends to the base 33 of the second cartridge housing portion 18, but does not extend over the base 33. In other words, the inwardly extending flange 34 leaves an opening 35 at the connection end of the first cartridge housing portion 16. The second cartridge housing portion 18 further comprises openings 36 around the circumference of the second cartridge housing portion 18 just above the base 33 at the connection end. The openings 36 in the second cartridge housing portion 18 and the opening 35 in the first cartridge housing portion 16 enable air to be drawn into the inner passage 19 of the second cartridge housing portion 18, and out of the inner passage 19 through the inner tube 23 and the air outlet 22 of the first cartridge housing portion 16./ The device 14 is shown in Figure 2. The device 14 comprises a device housing 38, which defines a device cavity 40 at a connection end 41 of the device 14. The device cavity 40 is configured to receive the connection end 21 of the cartridge 12. The device cavity 40 comprises an open end at the connection end 41 of the device 14, and a substantially closed end opposite the open end.

The device 14 further comprises an inductor coil 42. The inductor coil 42 circumscribes a portion of the device cavity 40. The inductor coil 42 is made with a copper wire having a round circular section, and is arranged on a coil former element (not shown). In this embodiment, the inductor coil 42 is a helical coil, and has a circular cross-section when viewed parallel to the longitudinal axis of the device 14.

When the connection end 21 of the cartridge 12 is received in the device cavity 40 of the device 14, as shown in Figure 3, the inductor coil 42 is aligned with the heater assembly 30 of the cartridge, such that the inductor coil 42 is aligned with the susceptor element 32. The susceptor element 32 and the inductor coil 42 together form an inductive heating assembly 43.

The device 14 further comprises a controller 44 and a power supply 45, which also form part of the inductive heating assembly 43. The power supply 45 comprises a rechargeable lithium ion battery, which is rechargeable via an electrical connector (not shown) at a distal end of the device 14, opposite the connection end 41. The controller 44 is connected to the power supply 45, and to the inductor coil 42, such that the controller 44 is able to control a supply of power to the inductor coil 42 from the power supply 45. The controller 44 and the power supply 45 are configured to supply an alternating current to the inductor coil 42.

When an alternating current is supplied to the inductor coil 42, the inductor coil 42 generates an alternating magnetic field in the device cavity 40. When the connection end 21 of the cartridge 12 is received in the device cavity 40, the alternating magnetic field generated by the inductor coil 42 is generated in the region of the susceptor element 32, which is aligned with the inductor coil 42. The inductor coil 42 has a similar length to the susceptor element 32, such that the alternating magnetic field generated by the inductor coil 42 penetrates the length of the susceptor element 32.

The device 14 further comprises a flux concentrator 46, which partially surrounds the inductor coil 42 and is configured to attenuate the alternating magnetic field generated by the inductor coil 42 in the direction radially outwardly from the device. This may reduce interference between the alternating magnetic field and other nearby electronic devices and reduce the risk of the alternating magnetic field inductively heating nearby objects outside of the aerosol-generating system.

The device 14 further comprises a pushing element 47, which extends into the device cavity 40 from the substantially closed end in the direction of the longitudinal axis of the device. The pushing element 47 has transverse cross-section, perpendicular to the longitudinal axis of the device, with a similar a size and shape to the opening 35 at the connection end of the first cartridge housing part 16. As such, when the connection end 21 of the cartridge 12 is received in the device cavity 40, the pushing element 47 extends through the opening 35 at the connection end of the first cartridge housing part 16 and contacts the base 33 of the second cartridge housing part 18.

As shown in Figures 3, 4 and 5, when the connection end 21 of the cartridge 12 is received in the device cavity 40, the pushing element 47 pushes the base 33 of the second cartridge housing part 18 relative to the first cartridge housing part 16, from the storage position to the use position, towards the mouth end of the first cartridge housing part 16. The length of the pushing element 47 is slightly greater than the distance required for the second cartridge housing part 18 to be moved from the storage position to the use position, so that the cartridge is fully moved from the storage position to the use position when the connection end 21 of the cartridge 12 is received in the device cavity 40.

Also as shown in Figure 3, when the connection end 21 of the cartridge 12 is received in the device cavity 40, an air inlet 48, and air gap 49 are defined between the first cartridge housing part 18 and the device housing 38 to enable ambient air to be drawn into the aerosol-generating system 10. The air gap 49 extends the length of the connection end 21 of the cartridge 21 and the length of the device cavity 40, and between the inwardly extending flange 34 of the first cartridge housing part 16 and the substantially closed base of the device cavity 40. A flow restriction 50 is defined between the inwardly extending flange 34 and the pushing element 47. The flow restriction 50 will be described in more detail later on with reference to Figures 4-7.

Also as shown in Figure 3, when the connection end 21 of the cartridge 12 is received in the device cavity 40, an airflow cavity 51 is defined between an inner surface of the first cartridge housing part 16 and the pushing element 47. The airflow cavity 51 is bounded by the inwardly extending flange 34 of the first cartridge housing part 16 and the second stop 28 of the second cartridge housing part 18. As such, surfaces of the airflow cavity are partially defined by surfaces of the housing 38 of the device 14 (i.e. a surface of the pushing element 47) and by surface of the housing of the cartridge 12 (i.e. surfaces of the first and second cartridge housing parts 16, 18).

An airflow path is defined through the aerosol-generating system 10 when the connection end 21 of the cartridge 12 is received in the device cavity 40. The airflow path comprises the air inlet 48, the air gap 49, the flow restriction 50, the airflow cavity 51 , the openings 36 around the circumference of the second cartridge housing part 18, the inner passage 19 of the second cartridge housing part 18, the inner tube 23 of the first cartridge housing part 16, and the air outlet 22 of the first cartridge housing part 16. In use, a user may draw on the mouth end 20 of the cartridge 12, and draw ambient air into the aerosol-generating system 10 at the air inlet 48, through the airflow path, and out of the aerosol-generating system 10 at the air outlet 22 for inhalation. Ambient air enters the aerosolgenerating system 10 at the air inlet 48 between the cartridge housing and the device housing 38, through the air gap 49 to the flow restriction 50. Air passes through the flow restriction 50 into the airflow cavity 51 and out of the airflow cavity 51 into the inner passage 19 of the second cartridge housing part 18 through the openings 36. Air in the inner passage 19 flows over the susceptor element 31 , through the inner tube 23, and out of the aerosol-generating system at the air outlet 22. Airflow through a portion of the aerosol-generating system is shown by the dashed arrows in Figure 8.

The device 14 further comprises a pressure sensor 52 arranged to sense the pressure in the airflow cavity 51. The pressure sensor 52 is arranged in a pressure sensor cavity 53 partially arranged in the pushing element 47. An additional airflow path 54 is provided between the pressure sensor cavity 53 and the airflow cavity 51 , through the pushing element 47, to enable the pressure sensor 52 arranged in the pressure sensor cavity 53 to sense the pressure in the airflow cavity 51 .

The pressure sensor 52 is connected to the controller 44. The controller 44 receives pressure measurements from the pressure sensor 52. The controller 44 is configured to determine whether a user is taking a puff on the aerosol-generating system based on pressure measurements received from the pressure sensor 52.

The flow restriction 50 in the airflow path causes a pronounced pressure drop in the airflow cavity 51 when a user takes a puff on the aerosol-generating system by drawing on the mouthpiece. This pressure drop makes the detection of a puff more reliable, and faster, than if the flow restriction 50 were not present, and so did not cause such a pronounced pressure drop in the airflow cavity 51 in the event of a puff.

As shown in Figures 6 and 7, in this embodiment the flow restriction 50 is defined between the housing 38 of the device 14 and the housing of the cartridge 12. The flow restriction 50 is defined by a surface of the inwardly extending flange 34 of the first cartridge housing part 16 and a surface of the pushing element 47, which is a surface of the housing 38 of the device 12. In this embodiment, the flow restriction 50 is formed by a “vertical” channel extending in the direction of the length of the cartridge 12 and the device 14, between the radially innermost surface of the inwardly extending flange 34 of the first cartridge housing part 16 and a radially outer surface of the pushing element 47 of the device housing 38. The flow restriction 50 is the portion of the airflow path through the aerosolgenerating system with the smallest cross-sectional area. The cross-sectional area of the flow restriction 50 may define the resistance to draw (RTD) through the flow restriction and the airflow path. Accordingly, the cross-sectional area of the flow restriction may be chosen to provide a desired RTD through the airflow path. In this embodiment, the width 55 of the flow restriction 50 between the inwardly extending flange 34 and the pushing element 47, which is shown in Figure 6, has the smallest dimension of any portion of the airflow path. In this embodiment, the flow restriction 50 is arranged immediately adjacent the airflow cavity 51 , leading directly onto the airflow cavity 51 . A cross-section of the aerosol-generating system, through line 56 of Figure 6, is shown in Figure 7, wherein the narrow flow restriction 50 is shown leading to the airflow cavity 51 .

Also, as shown in Figure 7, the cartridge 12 and the device 14 generally have a stadium shaped transverse cross-sectional shape. However, it will be appreciated that the cartridge and the device may have other transverse cross-sectional shapes, such as circular, elliptical, or polygonal, without altering how the aerosol-generating system works.

In use, the connection end 21 of the cartridge 12 is inserted into the device cavity 40 of the device 14. The pushing element 47 enters the cartridge 12 at opening 35, and pushes the base 33 of the second cartridge housing part 18, such that the second cartridge housing part 18 moves towards the mouth end of the first cartridge housing part 16, moving the cartridge from the storage position to the use position. Liquid aerosol-forming substrate 26 held in the liquid reservoir 25 is able to flow from the liquid reservoir 25 to the heater assembly 30 when the connection end 21 of the cartridge 12 is fully received in the device cavity 40.

When a user takes a puff on the mouth end 20 of the cartridge 12, air is drawn into the aerosolgenerating system at the air inlet 48, through the air gap 49 and the flow restriction 50 into the airflow cavity 51. The pressure drop in the airflow cavity 51 caused by the user’s puff is detected by the pressure sensor 52 in the pressure sensor cavity 53, and the controller 44 determines that a puff has been taken on the aerosol-generating system 10 based on pressure measurements received from the pressure sensor 52. The controller 44, on detecting a puff, causes an alternating current from the power supply 45 to be supplied to the inductor coil 42, which generates an alternating magnetic field in the device cavity 40. The susceptor element 31 of the cartridge 12 is penetrated by the alternating magnetic field and is heated by Joule heating through induction of eddy currents in the susceptor element, and through hysteresis losses. The heated susceptor element 31 heats the liquid aerosol-forming substrate 26 at the susceptor element 31 , which releases volatile compounds in a vapour into the inner passage 19 of the second cartridge housing 18. The vapour is entrained in the airflow through the inner passage 19, as air from the airflow cavity 51 is drawn into the inner passage through the openings 36 close to the base 33 of the second cartridge housing part. The vapour cools as it is drawn along the inner passage into the inner tube 23 of the first cartridge housing part 16, and condenses to form an aerosol. The aerosol is drawn out of the aerosol-generating system 10 at the air outlet 22, where it is inhaled by the user.

It will be appreciated that in other embodiments the flow restriction may be provided in a different location in the airflow path. For example, the flow restriction may be defined by a surface of the substantially closed end of the device cavity and a surface of the inwardly extending flange of the first cartridge housing part, at the connection end. In these embodiments, the flow restriction may be spaced from the airflow cavity. In some embodiments, the flow restriction may be defined both between a surface of the inwardly extending flange of the first cartridge housing part and a surface of the pushing element of the device housing, and a surface of the substantially closed end of the device cavity and a surface of the inwardly extending flange of the first cartridge housing part, at the connection end.

A portion of another example of an aerosol-generating system according to the present disclosure is shown in Figures 9 and 10. The example of Figures 9 and 10 is substantially identical to the aerosol-generating system of Figures 1-8, and like features are referred to with like reference numerals. The only difference between the aerosol-generating system 10 of Figures 9 and 10 and the aerosol-generating system 10 of Figures 1 -8 is that in the aerosol-generating system 10 of Figures 9 and 10, the flow restriction 50 is arranged in a different location in the airflow path, and the flow restriction 50 is not arranged immediately adjacent the airflow cavity 51 .

As shown in Figures 9 and 10, the flow restriction 50 is provided in a portion of the airflow path defined by an open channel 57 in the substantially closed end of the device cavity 40 and a bottom surface of the inwardly extending flange 34 of the first cartridge housing part 16, at the connection end. In this embodiment, the flow restriction 50 is a “horizontal” channel extending in the direction of the width of the cartridge 12 and the device 14, formed between the surfaces of the open channel 57 at the substantially closed end of the device cavity 40 and the bottom face of the inwardly extending flange 34 of the first cartridge housing part 16. Again, in this embodiment the flow restriction 50 is the portion of the airflow path through the aerosol-generating system 10 with the smallest cross- sectional area. The cross-sectional area of the flow restriction 50 may define the resistance to draw (RTD) through the flow restriction and the airflow path. Accordingly, the cross-sectional area of the flow restriction may be chosen to provide a desired RTD through the airflow path. The width 55 and the depth 58 of the flow restriction 50 determine the cross-sectional area of the flow restriction 50. In this embodiment, the depth 58 of the flow restriction 50, which is shown in Figure 9, has the smallest dimension of any portion of the airflow path.

In the arrangement of the embodiment of Figures 9 and 10, the flow restriction 50 is spaced from the airflow cavity 51 , with a further air gap 49 being provided between the flow restriction 50 and the airflow cavity 51 . The additional air gap 49 is formed by the radially outer surface of the pushing element 47 of the device housing 38 and the radially innermost surface of the inwardly extending flange 34 of the second cartridge housing part 18.

In the arrangement of the embodiment of Figures 9 and 10, it may be necessary to seal the open end of the open channel 57, when the cartridge 12 is received in the device cavity 40 of the device 14, to form the flow restriction. The seal may be a liquid-tight seal, or preferably an air-tight seal. Providing an air-tight seal, which may be referred to as a hermetic seal, may ensure that the airflow through the flow restriction 50 is closely controlled, resulting in a predictable and consistent resistance to draw through the airflow path. Such a seal may be achieved by providing a sealing element, such as an elastomeric sheet between the substantially closed end of the device cavity 40 and the bottom surface of the inwardly extending flange 34 of the first cartridge housing part 16. The sealing element may be provided either in the device 14, at the substantially closed end of the device cavity 40, or in the cartridge 12, on the bottom surface of the inwardly extending flange 34 of the first cartridge housing part 16.

It will be appreciated that in some embodiments, the flow restriction may comprise both the “horizontal” channel of the embodiment of Figures 1 -8 and the “vertical” channel of the embodiment of Figures 9 and 10. In other words, the flow restriction may comprise both the “vertical” channel extending in the direction of the length of the cartridge 12 and the device 14, between the radially innermost surface of the inwardly extending flange 34 of the first cartridge housing part 16 and a radially outer surface of the pushing element 47 of the device housing 38, and the “horizontal” channel extending in the direction of the width of the cartridge 12 and the device 14, formed between the surfaces of the open channel 57 in the substantially closed end of the device cavity 40 and the bottom face of the inwardly extending flange 34 of the first cartridge housing part 16.

A portion of another example of an aerosol-generating system according to the present disclosure is shown in Figures 11 and 12. The example of Figures 11 and 12 is substantially identical to the aerosol-generating system of Figures 1-8, and like features are referred to with like reference numerals. The only difference between the aerosol-generating system 10 of Figures 11 and 12 and the aerosol-generating system 10 of Figures 1 -8 is that in the aerosol-generating system 10 of Figures 11 and 12, the device 14 comprises the flow restriction 50, and the flow restriction is not arranged immediately adjacent the airflow cavity 51 .

Providing the flow restriction 50 in the device 14, rather than between the cartridge 12 and the device 14, may make it easier to control the dimensions of the flow restriction during use of the aerosol-generating system 10.

As shown in Figures 11 and 12, the flow restriction 50 is provided in a passage through a portion of the device housing 38 below the substantially closed end of the device cavity 40. Again, the flow restriction 50 is the portion of the airflow path through the aerosol-generating system 10 with the smallest cross-sectional area. The cross-sectional area of the flow restriction 50 may define the resistance to draw (RTD) through the flow restriction and the airflow path. Accordingly, the cross- sectional area of the flow restriction may be chosen to provide a desired RTD through the airflow path. In this embodiment, the depth 58 and width of the flow restriction 50 determine the cross- sectional area of the flow restriction. In this embodiment, the depth 58 of the flow restriction 50, which is shown in Figure 12, has the smallest dimension of any portion of the airflow path. In this embodiment, the flow restriction 50 is spaced from the airflow cavity 51 , with a further air gap 49 being provided between the device housing 38 and a surface of the inwardly extending flange 34 of the second cartridge housing part 18. Airflow through a portion of the aerosol-generating system 10 is shown by the dashed arrows in Figure 11 .

It will be appreciated that the above examples are only examples of the present disclosure, and modifications may be made to the examples within the spirit of the disclosure. For example, it will be appreciated that in some examples, the device 14 may comprise at least one of the air inlet 48 and the air gap 49. It will also be appreciated that any suitable number of air inlets 48 and air gaps 49 may be provided to provide a desirable aerosol delivery to a user. The aerosol-generating system 10 may comprise a resistive heating element, rather than an inductive heating assembly 43. The cartridge 12 may comprise a single cartridge housing, without the movable first and second cartridge housing parts 16, 18, and the device 14 may not comprise a pushing element 47 extending into the device cavity. The airflow cavity may be provided in a different location in the airflow path. The airflow cavity may be provided between other portions of the cartridge housing and the device housing. The flow restriction may be provided in a different location in the airflow path. The flow restriction may be provided between other portions of the cartridge housing and the device housing

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 10 percent (10%) of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

1. An aerosol-generating system comprising: a cartridge comprising: a cartridge housing; a liquid reservoir configured to hold a liquid aerosol-forming substrate; and a heating element configured to heat liquid from the liquid reservoir; and a device comprising: a device housing defining a device cavity configured to receive a portion of the cartridge; wherein: when the portion of the cartridge is received in the device cavity, the aerosol-generating system comprises an airflow path defined between an air inlet and an air outlet; when the portion of the cartridge is received in the device cavity, an airflow cavity is located in the airflow path, the airflow cavity being defined between the cartridge housing and the device housing; and the device comprises a pressure sensor arranged to detect the pressure in the airflow cavity.

2. An aerosol-generating system according to claim 1 , wherein a flow restriction is arranged in the airflow path between the air inlet and the airflow cavity, and optionally wherein the flow restriction is arranged immediately upstream of the airflow cavity.

3. An aerosol-generating system according to claim 2, wherein at least one of: the flow restriction is a portion of the airflow path having a width that is smaller than the width of the airflow cavity; the flow restriction is a portion of the airflow path having the smallest width of any portion of the airflow path; the flow restriction is a portion of the airflow path having a cross-sectional area that is smaller than the cross-sectional area of the airflow cavity; and the flow restriction is a portion of the airflow path having the smallest cross-sectional area of any portion of the airflow path.

4. An aerosol-generating system according to claim 2 or claim 3, wherein the aerosol-generating device comprises the flow restriction.

5. An aerosol-generating system according to claim 2 or claim 3, wherein when the portion of the cartridge is received in the device cavity, the flow restriction is defined between the cartridge housing and the device housing.

6. An aerosol-generating system according to claim 5, wherein at least a portion of a surface of the cartridge housing defines at least a portion of a surface of the flow restriction, and at least a portion of a surface of the device housing defines at least a portion of a surface of the flow restriction.

7. An aerosol-generating system according to any one of claims 1 to 6, wherein at least a portion of a surface of the cartridge housing defines at least a portion of a surface of the airflow cavity, and at least a portion of a surface of the device housing defines at least a portion of a surface of the airflow cavity.

8. An aerosol-generating system according to any one of claims 1 to 7, wherein when a portion of the cartridge is received in the device cavity, the air inlet of the airflow path is defined between the cartridge and the device.

9. An aerosol-generating system according to any one of claims 1 to 8, wherein the pressure sensor is located in a pressure sensor cavity in the device, and optionally wherein an additional airflow path is provided between the airflow cavity and the puff sensor cavity to enable air to flow between the airflow cavity and the puff sensor cavity.

10. An aerosol-generating system according to any one of claims 1 to 9, wherein the device cavity comprises: an open end to enable the portion of the cartridge to be received in the device cavity; and a substantially closed end, opposite the open end, and wherein optionally the device cavity meets the airflow path at the substantially closed end.

11 . An aerosol-generating system according to claim 10, wherein the device housing comprises a pushing element, and wherein the pushing element extends into the device cavity from the substantially closed end.

12. An aerosol-generating system according to claim 11 , wherein the cartridge housing comprises two parts, a first cartridge housing part, and a second cartridge housing part, wherein the second cartridge housing part is movable relative to the first cartridge housing part, and wherein the pushing element is arranged to contact the second cartridge housing part when the portion of the cartridge is received in the device cavity and move the second cartridge housing part relative to the first cartridge housing part.

13. An aerosol-generating system according to claim 11 or claim 12, wherein at least a portion of a surface of the pushing element defines at least a portion of a surface of the airflow cavity when the portion of the cartridge is received in the device cavity.

14. An aerosol-generating system according to any one of claims 1 to 13, wherein the aerosol- generating system further comprises an inductive heating assembly comprising an inductor coil and the heating element, wherein the device comprises the inductor coil, and wherein the heating element comprises a susceptor element.

15. An aerosol-generating system according to claim 14, wherein the device is configured to supply a varying current to the inductor coil, wherein the inductor coil is configured to generate an alternating magnetic field when supplied with a varying current, and wherein the inductor coil and susceptor element are arranged such that the varying magnetic field penetrates the susceptor element when the portion of the cartridge is received in the device cavity.