Aerosol generator with dual-mode heating

Abstract

An aerosol generator configured to generate aerosols from an aerosol-forming substrate defines a cavity for receiving at least a portion of the aerosol-forming substrate, and an airflow path upstream of the cavity through which a user can draw air when the device is in use. The airflow path connects the cavity to the external environment. The device comprises a first heating section located within the cavity, and a second heating section located in thermal contact with the airflow path upstream of the cavity.

Description

[Technical Field]

[0001] This disclosure relates to an aerosol generator. This disclosure also relates to an aerosol generating system comprising an aerosol generator, and a method for controlling an aerosol generator. [Background technology]

[0002] Some known aerosol generating systems comprise an aerosol generating device and an aerosol generating article having an aerosol-forming substrate. The aerosol generating device heats the aerosol-forming substrate of the aerosol generating article in order to form an aerosol when in use.

[0003] Aerosol-generating articles in which an aerosol-forming substrate, such as a tobacco-containing substrate, is heated rather than burned are known in the art. Typically, in such aerosol-generating articles, aerosols are generated by heat transfer from a heat source to the aerosol-forming substrate.

[0004] For example, electrically operated aerosol generators, such as handheld aerosol generators, can be used in such aerosol-generating articles. Such electrically operated aerosol generators may include a heating element configured to heat an aerosol-forming substrate to a temperature of several hundred degrees Celsius. This causes volatile compounds entrained in the air drawn through the aerosol-generating article to be released from the aerosol-forming substrate. As the released compounds cool, they condense or form nuclei to create aerosols.

[0005] Several embodiments of aerosol generators for consuming aerosol-generating articles have been disclosed in the Art. Such a device may include, for example, an electrically heated aerosol generator in which the aerosol is generated by heat transfer from one or more electric heater elements of the aerosol generator to the aerosol-generating elements of the aerosol-generating article. For this purpose, the aerosol-generating article may be partially received within a heated cavity of the aerosol generator such that the upstream end of the aerosol-generating article is inserted into the cavity, while the downstream end of the aerosol-generating article protrudes out of the cavity.

[0006] For example, when an aerosol-generating article is received in a heating cavity, an electrically heated aerosol generator has been proposed that includes an internal heater blade adapted to be inserted into the aerosol-generating substrate. Alternatively, heating of the aerosol-generating substrate is achieved using external heating, such as by a tubular heater element that at least partially defines a heating cavity into which the aerosol-generating article is inserted, or by a tubular heater element otherwise coupled to a tubular element that defines the heating cavity.

[0007] Induction-heated aerosol generating articles are also proposed, for example, in WO2015 / 176898. These aerosol generating articles comprise an aerosol generating element comprising an aerosol generating substrate, such as a tobacco-containing substrate, and a susceptor disposed within the aerosol generating substrate. Functional coupling between the susceptor and the induction heater element of the aerosol generating device is achieved when the aerosol generating article is partially received within the heating cavity of the aerosol generating device.

[0008] Solid aerosol generating substrates need to be heated to a temperature sufficient to facilitate the extraction of aerosol species (e.g., nicotine and glycerin). Existing heaters are typically configured to supply heat so that the solid aerosol generating substrate is exposed to temperatures within this range throughout. However, this heating setting may have the disadvantage of being less battery efficient in use. Furthermore, this heating setting may limit the use of the solid aerosol generating substrate to a predetermined number of puffs, a finite number of puffs, or a predetermined number of minutes. Moreover, maintaining the solid aerosol generating substrate at a temperature sufficient to facilitate the extraction of aerosol species between puffs may also undesirably increase the risk of generating harmful and potentially harmful components (HPHCs).

[0009] It would be desirable to provide an aerosol generator adapted to address at least one of the aforementioned drawbacks in part. [Overview of the project]

[0010] This disclosure relates, for example, to an aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a use session. The device may be configured to heat the aerosol-forming substrate to a standby temperature or a maintenance temperature during a use session. The device may be configured such that the temperature of the aerosol-forming substrate rises from the standby temperature at which the user inhales smoke to, for example, an operating temperature. For example, the device may be configured to supply a thermal boost to the aerosol-forming substrate during user inhalation performed during a user session. Such a configuration may enable the aerosol-forming substrate to be heated to a first temperature, for example, a standby temperature that is or slightly below the temperature required to form an aerosol, and then, during user inhalation smoke, to a raised temperature, for example, an operating temperature, that exceeds the temperature required to form an aerosol.

[0011] By selecting an appropriate standby temperature, the aerosol-forming substrate can be boosted to its operating temperature almost instantaneously when additional thermal energy is applied to the substrate. The temperature can then be allowed to drop back down to the standby temperature after user inhalation.

[0012] During inhalation, the combination of heating to standby temperature and rapid temperature rise to operating temperature allows for efficient extraction of desirable components of the aerosol-forming substrate, such as nicotine, flavor components, and aerosol-forming substances like glycerin, without overheating the substrate over a wide area. The formation of undesirable aerosol components can be reduced, and optimal extraction of desirable components can be achieved.

[0013] The aerosol generator may define a cavity for receiving at least a portion of an aerosol-forming substrate. The aerosol generator may define an airflow path upstream of the cavity through which a user can draw air when the device is in use. The airflow path may connect the cavity to the external environment, for example, by fluid connection between the cavity and the external environment. The device may include a heating section located in the cavity, for example, a heating section for directly heating the cavity. The device may also include a second heating section located in thermal contact with the airflow path upstream of the cavity, for example, a second heating section for directly heating the airflow path upstream of the cavity.

[0014] According to one aspect of the present invention, an aerosol generator is provided, configured to generate an aerosol from an aerosol-forming substrate. The device defines a cavity for receiving at least a portion of the aerosol-forming substrate and an upstream airflow path of the cavity through which a user can draw air when the device is in use, the airflow path connecting the cavity to the external environment. The device further comprises a first heating section located in the cavity. The first heating section may comprise a heater or heating means arranged to directly heat the cavity and any contents of the cavity, regardless of whether air flows through the airflow path. The device further comprises a second heating section located in thermal contact with the upstream airflow path of the cavity. The second heating section may comprise a heater or heating means arranged to heat the air in the upstream airflow path of the cavity.

[0015] Advantageously, the first heating element may be used to heat the aerosol-forming substrate positioned within the cavity to a first temperature, for example, a standby temperature, and the second heating element may be used to raise the temperature of the aerosol-forming substrate to an operating temperature higher than the standby temperature when the user inhales the smoke.

[0016] It should be noted that a cavity may be alternately referred to as a chamber, and the terms cavity and chamber may be used interchangeably herein, and that both refer to a part of an apparatus for receiving at least a portion of an aerosol-forming substrate so that the substrate may be heated and an aerosol is generated.

[0017] The first heating section may comprise a heater or heating means, which is arranged to at least partially surround the cavity. Therefore, the heater, which may be called an external heater, may be arranged to heat the cavity walls from all sides in order to help provide uniform heating of the cavity. The external heater can be a preferred heater for heating a substrate received within the cavity, as it allows the aerosol-forming substrate to be heated to a uniform temperature without contact between the substrate and the heater.

[0018] The first heating portion may include a heater disposed in contact with the wall of the cavity, for example, a resistive heater disposed in contact with the wall of the cavity. As an example, the first heating portion may include a flexible heater disposed in contact with the inner or outer surface of the cavity, for example, a polyimide flexible heater disposed in contact with the inner or outer wall of the cavity. Such a heater can directly heat the wall of the cavity by conduction. The cavity can be heated by direct radiation and convection from the cavity wall or, if the heater is located within the cavity, from the heater itself.

[0019] The inner surface of the resistive heater, which may be in the form of a flexible sheet, may be covered or coated with a protective film. For example, the heater may be coated with a thin film having a high thermal conductivity for diffusing the heat generated by the first heating portion. For example, the heater may be coated with a thin film having anti-adhesive properties.

[0020] The first heating portion may include a heater located within the cavity, for example, a projecting heater configured to penetrate an aerosol-forming substrate inserted into the cavity. Such a heater may provide direct contact with the aerosol-forming substrate inserted into the cavity, which can improve heating efficiency.

[0021] The first heating portion may include an induction heating device. For example, the first heating portion may include an inductor located outside the cavity configured to heat a susceptor located within the cavity, or a susceptor that contacts or forms part of the cavity wall. Therefore, the cavity wall may include or be entirely formed of a susceptor material such as stainless steel.

[0022] The susceptor, which may also be referred to as a susceptor element, may include or consist of one or more susceptor materials.

[0023] Suitable susceptor materials can include, but are not limited to, carbon, carbon-based materials, graphene, graphite, expanded graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Suitable susceptor materials can include ferromagnetic materials, such as ferromagnetic alloys like ferrite iron, ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrite. The susceptor material preferably contains more than 5 percent of a ferromagnetic or paramagnetic material, more preferably more than 20 percent of a ferromagnetic or paramagnetic material, and even more preferably more than 50 percent or more than 90 percent of a ferromagnetic or paramagnetic material. Preferred susceptor materials can include a metal, a metal alloy or carbon.

[0024] The device may include, for example, opposing electrodes supplied by a high-frequency AC signal through an impedance matching circuit, and a susceptor located within a cavity between the two opposing electrodes, and may include a capacitive or dielectric heater for heating an aerosol-forming substrate received within the cavity of the device to heat the aerosol-forming substrate.

[0025] The first heating portion is preferably configured to directly heat the aerosol-forming substrate received within the cavity. That is, the first heating portion can be configured or arranged to heat the aerosol-forming substrate within the cavity regardless of whether the user is smoking and causing air to flow through the airflow path.

[0026] The cavity includes an air inlet connecting the cavity to the airflow path upstream of the cavity. Thus, the user can inhale with an aerosol-generating article located within the cavity and, in so doing, draw air through the airflow path.

[0027] The second heating portion is preferably located in the airflow path upstream of the cavity. The second heating portion may include a heater located in the airflow path upstream of the cavity, for example, a resistance heater located in the airflow path upstream of the cavity. For example, the second heating portion may include a heater formed by at least one resistance heating element or resistance heating track. The second heating portion may include a resistance heating coil.

[0028] The second heating section may include a baffle located in the airflow path to direct the airflow through the second heating section. The baffle may form part of the resistance heating track.

[0029] Alternatively, or additionally, the second heating portion may include a heater disposed in contact with the outer surface of the second heating portion. Such a heater may be formed of a resistance heating element or a resistance heating track. For example, the heater may include a windable resistance heating track.

[0030] The second heating section may include an induction heating device. For example, the second heating section may include an inductor configured to heat a susceptor located in the airflow path upstream of the cavity. When the susceptor is heated, it can heat the air passing through the airflow path.

[0031] The second heating section may include a heat exchanger. Advantageously, the second heating section may include a permeable body, such as a porous body, through which an airflow path is defined. The porous body may contain or be a porous plug made of silicon dioxide. The permeable body may be configured to have a large internal surface area, for example, by using multiple channels or baffles that create a spiral airflow path through the permeable body. Thus, the permeable body, such as a porous body, can act as a heat exchanger to transfer heat from the permeable body to the air passing through it. The airflow path through the second heating section may have a predetermined drawdown resistance (RTD), and the permeable body may have an internal airflow path, such as an internal porosity, configured to provide such a predetermined RTD.

[0032] The ventilated body may have an opening. The opening may be located substantially in the radial center of the ventilated body. The opening may extend through the ventilated body so that the ventilated body is tubular. The ventilated body may have multiple openings. The multiple openings may be arranged in a radially symmetrical configuration around the ventilated body.

[0033] The second heating portion may comprise a heating element configured for resistance heating, which may be referred to as Joule heating, and the heating element comprises a polymer composite material containing a polymer matrix and a plurality of conductive particles dispersed within the polymer matrix. Such a heating element can function both as part of the structure of the heating element and as a heating element. Thus, portions of the heating element can be heated when an electric current passes through those portions of the heating element. The heating element may include a porous material. The heating element may include both a porous portion and a non-porous portion.

[0034] In some embodiments, a preferred polymer composite may comprise a polymer matrix and a plurality of nonmetallic conductive particles dispersed within the polymer matrix. For example, the plurality of nonmetallic conductive particles may comprise one or more of a plurality of carbon particles, such as graphite particles, and a plurality of boron nitride particles, such as hexagonal boron nitride particles. Thus, the conductive particles may comprise carbon particles, boron nitride particles, or a mixture of both. In preferred embodiments, the plurality of nonmetallic conductive particles comprises at least one of expanded graphite particles and graphite nanoplatelets.

[0035] The polymer matrix preferably contains at least one of polyether ether ketone (PEEK) and liquid crystal polymer (LCP).

[0036] The polymer matrix may consist of 22% to 33% by weight of polymer composite material.

[0037] Nonmetallic conductive particles may constitute 62 to 69 weight percent of the polymer composite material.

[0038] The polymer composite may further include at least one additive dispersed within the polymer matrix. For example, the at least one additive may be carbon black, or may contain carbon black.

[0039] The heating element of the second heating portion may be formed by processing polymer composite particles. The heating element portion may be formed by molding or extruding the polymer composite. The porous portion of the heating element is preferably formed by partially sintering polymer composite particles so that airflow paths are still defined through the porous body. The porous portion may comprise a porous plug formed by sintering polymer particles to provide a permeable body. The polymer particles sintered to form the porous portion or porous plug preferably have a number-average particle diameter of less than 1000 micrometers, for example less than 800 micrometers, for example 50 to 600 micrometers. The cross-sectional porosity of the porous plug is preferably greater than 15 percent and less than 45 percent. The total porosity of the porous plug is preferably 0.5 to 5 cubic centimeters, for example 2 to 3.5 cubic centimeters. The porous plug preferably provides a draw resistance of 10 mmH2O to 40 mmH2O, for example, about 15 mmH2O or about 20 mmH2O. The second heating portion may include an inductor coil extending around at least a portion of the heating body. For example, a power supply and control device may be connected to the induction coil and configured to supply a fluctuating current to the induction coil so that the induction coil generates a fluctuating magnetic field when in use. The inductor coil may be positioned in direct contact with the outer surface of the heating body.

[0040] Alternatively, or additionally, the heating element may contain or consist of a ceramic material, such as alumina or zirconia. Advantageously, ceramic materials can provide high thermal conductivity.

[0041] The aerosol generator is preferably configured to generate aerosols from an aerosol-forming substrate during a usage session, which includes the start and end of the usage session. Advantageously, the device may be configured to distinguish between smoke-inhaling and non-smoke-inhaling periods. The smoke-inhaling period may be defined as any period during a usage session in which the user is actively inhaling smoke. The non-smoke-inhaling period may be defined as any period during a usage session in which the user is not actively inhaling smoke.

[0042] The device is preferably configured to heat the aerosol-forming substrate during a usage session, with reference to two different target temperatures: a standby or maintenance target temperature and an operating target temperature. The standby target temperature is preferably higher than room temperature, and the operating target temperature is higher than the standby target temperature. A signal from a flow detector, such as a pressure sensor, is preferably used to control the temperature to either the standby target temperature or the operating target temperature.

[0043] Therefore, the device is preferably configured to control the temperature of the aerosol-forming substrate with respect to the operating target temperature during the smoke absorption period, with reference to the standby target temperature during the non-smoke absorption period. As a result, the substrate temperature is consistently maintained at the standby target temperature during the non-smoke absorption period. Once the start of user smoke absorption is detected, the temperature can be raised to the operating target temperature, and after user smoke absorption has ended, the temperature can be allowed to drop again to the standby target temperature.

[0044] Accordingly, the present invention may provide an aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, for example, the aerosol generator described above, the device configured to heat the aerosol-forming substrate during a usage session with reference to two different target temperatures, a standby target temperature and an operating target temperature, wherein the standby target temperature is higher than room temperature and the operating target temperature is higher than the standby target temperature, the device configured to heat the aerosol-forming substrate to the standby temperature during a usage session, the device further configured to heat the aerosol-forming substrate from the standby target temperature to the operating target temperature during user smoke extraction performed during the usage session, and the aerosol-forming substrate is made coolable from the operating target temperature after the user smoke extraction is completed.

[0045] Accordingly, according to certain aspects of the present invention, an aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, for example, the aerosol generator described above, is provided, the device configured to heat the aerosol-forming substrate during a usage session with reference to two different target temperatures, a standby target temperature and an operating target temperature, wherein the standby target temperature is higher than room temperature, and the operating target temperature is higher than the standby target temperature, the smoke absorption period is defined as any period during a usage session in which the user is actively smoke-absorbing, and the non-smoke absorption period is defined as any period during a usage session in which the user is not actively smoke-absorbing, the device configured to operate in standby mode during the non-smoke absorption period, the temperature of the aerosol-forming substrate being controlled with reference to the standby target temperature when operating in standby mode, and the device configured to operate in operating mode during the smoke absorption period, the temperature of the aerosol-forming substrate being controlled with reference to the operating target temperature when operating in operating mode.

[0046] Accordingly, according to certain aspects of the present invention, an aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, for example, the aerosol generator described above, is provided, the device is configured to heat the aerosol-forming substrate during a usage session according to a standby mode or an operating mode, during the standby mode the temperature of the aerosol-forming substrate is controlled with reference to a standby target temperature, during the operating mode the temperature of the aerosol-forming substrate is controlled with reference to an operating target temperature, where the standby target temperature is higher than room temperature and the operating target temperature is higher than the standby target temperature, the operation of the device changes from standby mode to operating mode when the user starts inhaling smoke and changes from operating mode to standby mode when the user ends inhaling smoke.

[0047] Accordingly, according to certain aspects of the present invention, an aerosol generator configured to supply energy to heat an aerosol-forming substrate to a standby temperature, and a second heating unit configured to heat the aerosol-forming substrate to an operating temperature during user fume extraction, may be provided. In certain embodiments, both the first and second heating units are activated at the start of a usage session, the first heating unit is configured to directly heat the aerosol-forming substrate received in a cavity, and the second heating unit is configured to heat the air drawn into the airflow path by user fume extraction.

[0048] The aerosol generator may be configured to detect user inhalation. The device may be further configured such that power is supplied to the second heating section only when the user is inhaling, and no power is supplied when the user is not inhaling. Alternatively, power may be supplied continuously to the second heating section, but the power supplied to the second heating section may increase while the user is inhaling.

[0049] The aerosol generator may be equipped with an airflow detector for detecting user inhalation. For example, the device may be equipped with a pressure sensor located in the airflow path, for example, in the airflow path upstream of a cavity. The device may be configured to use signals from the flow detector or flow detection means, such as the pressure sensor, to detect one or more user inhalations that occurred during a usage session.

[0050] If the device is configured to detect user smoke inhalation using sensors such as pressure sensors located within the airflow path, it may be preferable for the airflow path upstream of the cavity to act as a flow limiter, or to include a flow limiter. For example, a flow limiter may include a mechanical element such as an orifice plate located within the airflow path. In a further embodiment, a portion of the airflow path may be narrow enough to act as a flow limiter. Flow limiting may increase the velocity of the air drawn through the airflow path and may generate a pressure drop. Flow limiting may enhance the pressure drop created when the user draws air through the airflow path. Thus, flow limiting may increase the sensitivity of smoke inhalation detection. For example, an increased pressure drop associated with flow limiting within a portion of the airflow path may improve the ability of the pressure sensor to accurately detect user smoke inhalation.

[0051] The flow limiter can be a variable flow limiter. For example, the flow limiter may be a user-operable valve mechanism such as an adjustable valve or an adjustable screw. The use of such a variable flow limiter may allow the user to optimize the airflow through the device to account for different types of aerosol-generating articles. The limiting can be varied to optimize smoke detection for a particular user.

[0052] A portion of the airflow path upstream of the cavity is 3 mm 2 Less than, for example, 2mm 2 Less than 1.5 mm 2 Less than 0.5 mm 2 It may have a cross-sectional area of ​​less than 0.5 mm. A portion of the airflow path upstream of the cavity is 0.5 mm. 2Less than, for example, 0.4 mm 2 Less than 0.2 mm 2 Less than 0.1 mm 2 It may have a cross-sectional area less than . Such a cross-sectional area may provide flow limiting, for example, to amplify the sensitivity of a pressure sensor to changes in airflow associated with the user's smoke intake.

[0053] The draw resistance of a flow limiter causes a pressure drop that can be detected by a pressure sensor. Therefore, it may be desirable for the flow limiter upstream of the pressure sensor to provide sufficient draw resistance to cause a detectable pressure drop. Draw resistance can be more important than the absolute cross-sectional area of ​​the airflow path. For example, an airflow path with multiple small inlets may provide greater draw resistance, and therefore a greater pressure drop downstream of the inlets, than an airflow path with a single inlet having the same cross-sectional area as multiple inlets combined.

[0054] It may be preferable for the airflow path upstream of the cavity to have a drawdown resistance (RTD) greater than 10 mmH2O. This RTD can provide a detectable pressure drop to a pressure sensor. For example, the RTD may be between 10 mmH2O and 50 mmH2O. For instance, a portion of the airflow path equipped with a flow limiter may provide a drawdown resistance (RTD) between 10 mmH2O and 50 mmH2O.

[0055] The draw resistance used herein is measured according to the conditions presented in ISO 6565:2015. Therefore, the draw resistance of the airflow path between the inlet and the pressure sensor may be at least about 70 Pascals (Pa), for example, at least about 80 Pa, or at least about 90 Pa, or at least about 100 Pa, when measured according to the conditions presented in ISO 6565:2015. 100 Pa is about 10 millimeters of water column (mmH2O). The RTD may be at least 150 Pa, or at least 200 Pa, for example, at least about 450 Pa. 450 Pa is about 45 millimeters of water column (mmH2O). The conditions presented in ISO 6565:2015 include an outlet flow rate of 17.5 ml / second, an ambient temperature of 22 degrees Celsius, and a relative humidity of 60 percent.

[0056] The flow limiter may be any suitable flow limiter that causes a pressure drop in the airflow path, measurable by a pressure sensor, when the user is inhaling smoke from an aerosol generator.

[0057] In some preferred embodiments, the flow limiter is provided by an inlet in the airflow path. The inlet may include multiple inlets. For example, the inlet may comprise 1 to 30 inlets, or 4 to 25 inlets, or 7 to 20 openings. In some embodiments, the inlet may comprise 14 to 17 inlets. The single or multiple inlets may have any preferred size and shape to provide the desired draw resistance and pressure drop in the airflow path when the user is drawing smoke with the aerosol generator. For example, in some preferred embodiments, the inlet may comprise 5 to 25 inlets, more preferably 14 to 17 inlets, and each inlet may have a substantially circular cross-sectional shape with a diameter in the range of about 0.3 to 1.2 millimeters, more preferably about 0.5 millimeters.

[0058] The single or multiple inlets are preferably arranged to allow ambient air to be drawn into the aerosol generator. The single or multiple inlets may have a total cross-sectional area smaller than the cross-sectional area of ​​the airflow path immediately after the inlet.

[0059] A pressure sensor may be located in the flow limiter and may detect the pressure drop associated with the increase in air velocity due to flow limiting during user smoke extraction. The pressure sensor may be located upstream of the cavity but downstream of the flow limiter. The flow limiter may enhance the pressure drop associated with user smoke extraction, increase the sensitivity of the pressure sensor, and improve the accuracy of smoke extraction detection.

[0060] The airflow path upstream of the cavity may include a flow limiter, and further downstream of the flow limiter may include an expansion zone. The pressure sensor is preferably located in or within the expansion zone. This configuration allows for optimal amplification of the pressure sensor's sensitivity. For example, the airflow path may be at least partially defined by a channel having a first portion having a first cross-sectional area and a second portion having a second cross-sectional area larger than the first portion. The first portion preferably forms a flow limiter, and the pressure sensor is preferably located in the second portion.

[0061] The airflow path upstream of the cavity may further comprise a third portion having a third cross-sectional area, the third cross-sectional area being smaller than, for example, the second cross-sectional area of ​​the third portion which forms a second flow limiting section.

[0062] The airflow path upstream of the cavity may include a first flow limiter and a second flow limiter, with a pressure sensor located between the first and second flow limiters, for example, in an expansion section or expansion chamber located between the first and second flow limiters. The second flow limiter may, advantageously, help prevent blowback of steam from the steam chamber, which could potentially contaminate the pressure sensor.

[0063] An aerosol generator may have multiple air intakes that allow air to flow into a cavity. For example, the device may have multiple air intakes, each associated with an airflow path leading to a cavity. A pressure sensor may be located in one of these airflow paths. Two or more airflow paths may be associated with a pressure sensor. This can help to create some degree of redundancy in the system.

[0064] Multiple air intakes may supply airflow paths into an expanded cavity located downstream of the air intakes and upstream of the cavity. The pressure sensor is preferably located within the expanded cavity. The total cross-sectional area of ​​the multiple air intakes is preferably smaller than the cross-sectional area of ​​the expanded cavity. Therefore, the airflow paths through multiple inlets upstream of the expanded cavity containing the pressure sensor can provide a drawdown resistance (RTD) greater than 10 mmH2O, for example, greater than 20 H2O or greater than 30 H2O, preferably 10 mmH2O to 50 mmH2O.

[0065] The aerosol generator may include a second pressure sensor configured to sense ambient pressure. The ambient pressure sensor may provide a signal representing background pressure to help improve the accuracy of smoke inhalation detection, functioning as a reference signal or baseline signal. For example, small pressure changes occur naturally due to changes in weather, or when the user changes altitude, such as by climbing stairs, or when there is sudden noise. Measuring background pressure can help prevent misreading of smoke inhalation by the user.

[0066] The airflow path may be partially defined by a channel extending adjacent to or in contact with a heater. For example, the airflow path may extend in thermal contact with a heater configured to heat an aerosol-forming substrate located within a cavity. Thus, the incoming airflow can be partially heated by the same heater configured to heat the substrate within the cavity. This can capture some of the thermal energy that would otherwise be lost. By making the airflow path heatable in this way, less energy may be required to achieve the desired temperature in the aerosol-forming substrate.

[0067] The device may include a pressure sensor, such as an absolute pressure sensor, for example, a piezoresistive pressure sensor. The pressure sensor may be any suitable type of pressure sensor. The pressure sensor may be an absolute pressure sensor configured to determine the absolute pressure at a location in the airflow path. The pressure sensor may be a gauge pressure sensor configured to detect relative pressure at a location in the airflow path in comparison to the ambient pressure adjacent to the aerosol generator. The pressure sensor may be a differential pressure sensor configured to detect the pressure difference between a first location in the airflow path and a second location 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 microelectromechanical system (MEMS) pressure sensor. Advantageously, the MEMS pressure sensor may be small enough to fit inside the aerosol generator without significantly increasing the size of the aerosol generator. A non-limiting example of a suitable absolute pressure sensor is the MEMS nanopressure sensor LPS22HBTR manufactured by STMicroelectronics, which has an operating pressure of approximately 26 kilopascals (kPa) to approximately 126 kilopascals (kPa) and dimensions of 2 mm × 2 mm × 0.76 mm.

[0068] The aerosol generator disclosed herein may be configured to heat an aerosol-forming substrate during a usage session with reference to two different target temperatures, a standby target temperature and an operating target temperature. The standby target temperature is higher than room temperature, and the operating target temperature is higher than the standby target temperature. The device may be configured to heat the aerosol-forming substrate to the standby temperature during a usage session, and may be further configured to heat the aerosol-forming substrate from the standby target temperature to the operating target temperature during user fume extraction performed during the usage session. Preferably, the aerosol-forming substrate is made coolable from the operating target temperature after user fume extraction is completed.

[0069] The standby target temperature is preferably too low to release substantial aerosols from the aerosol-forming substrate. In other words, the standby temperature may be below the effective aerosolization temperature of the aerosol-forming material or substrate components. For example, the standby target temperature may be lower than the vaporization temperature or effective boiling point of the aerosol-forming material or mixture of aerosol-forming materials in the aerosol-forming substrate. For example, the standby target temperature may be set lower than the boiling point of propylene glycol, or lower than the boiling point of glycerol, or lower than the boiling point of a particular mixture of propylene glycol and glycerol used as an aerosol-forming material in the aerosol-forming substrate. The standby temperature may alternatively be referred to as the maintenance temperature.

[0070] The standby target temperature may be less than 250°C, for example, less than 230°C, for example, less than 210°C, preferably less than 200°C, for example, less than 180°C, or less than 160°C. The standby target temperature may also be between 50°C and 250°C, for example, between 80°C and 200°C, for example, between 100°C and 180°C.

[0071] The target operating temperature is preferably high enough to release aerosols from the aerosol-forming substrate. In other words, the operating temperature may be above the effective aerosolization temperature of the substrate. For example, the target operating temperature may be higher than the effective boiling point of the aerosol-forming material or aerosol-forming material mixture of the aerosol-forming substrate, for example, higher than the boiling point of propylene glycol, or higher than the boiling point of glycerol, or higher than the boiling point of a particular mixture of propylene glycol and glycerol used as the aerosol-forming material in the aerosol-forming substrate.

[0072] The target operating temperature may be above 160°C, for example above 180°C, or above 200°C, or above 250°C, for example above 280°C, or above 300°C, or above 320°C, or above 340°C. The target operating temperature may also be between 160°C and 400°C, for example between 180°C and 340°C, or for example between 220°C and 300°C.

[0073] The standby target temperature may remain constant throughout the entire duration of the usage session. Alternatively, the standby target temperature may vary over the duration of the usage session. That is, the standby target temperature may evolve over the course of the usage session to account for the depletion of aerosol-forming components as the user inhales during the session.

[0074] The target operating temperature may remain constant throughout the entire duration of the usage session. Alternatively, the target operating temperature may vary over the duration of the usage session. The target operating temperature may also vary from one smoke inhalation to the next. Fluctuations in the target operating temperature, such as an increase in the target operating temperature, may help optimize aerosol delivery from the aerosol-forming substrate as the aerosol-forming components become depleted during the course of the usage session.

[0075] A usage session preferably has a start and an end. The aerosol-forming substrate is preferably heated to a standby target temperature at the start of the usage session and maintained above the standby target temperature for the duration of the usage session until the end of the usage session. A usage session may be defined between the start and end of the usage session, the smoke absorption period may be defined as any period within the usage session in which the user is actively performing smoke absorption, the non-smoke absorption period may be defined as any period within the usage session in which the user is not actively performing smoke absorption, and the temperature of the aerosol-forming substrate may be controlled with reference to the standby target temperature during the non-smoke absorption period and the operating target temperature during the smoke absorption period.

[0076] Preferably, each of the one or more inhalations performed during a usage session has an inhalation start and an inhalation end, and the period between the inhalation start and the inhalation end is defined as the inhalation period.

[0077] A usage session may have a usage session duration, for example, a predetermined duration set by referring to time, or by referring to usage parameters, or by referring to both time and usage parameters. The usage parameters may preferably be selected from a list consisting of the number of user inhalations performed during the usage session, the volume of aerosols generated during the usage session, and the power supplied to the heater during the usage session.

[0078] The device is preferably configured to detect one or more user inhalations performed during a usage session. The device is preferably configured to detect the start of a user inhalation performed during a usage session, for example, each user inhalation performed during the usage session. The device is preferably configured to detect the end of a user inhalation performed during a usage session, for example, each user inhalation performed during the usage session. Therefore, the device may be configured to determine the duration of a user inhalation performed during a usage session, for example, each user inhalation performed during the usage session.

[0079] Advantageously, the device can be configured to characterize user inhalation performed during a usage session, for example, each inhalation performed during the usage session. For example, the device can be configured to determine the volume of aerosol generated during user inhalation during a usage session, for example, each user inhalation during the usage session.

[0080] In some embodiments, the aerosol generator may be configured to monitor parameters indicating aerosol generation during the operation of the aerosol generator and to use the monitored parameters in the detection of one or more user inhalations that occurred during a usage session. In such embodiments, inhalations may be detected without the need for sensors. The monitored parameters may be analyzed to identify user inhalations, which are defined by the inhalation start and end points.

[0081] The monitored parameter may represent the power supplied by the power source. Analysis of the monitored parameter may include the steps of calculating a first characteristic of the monitored parameter and analyzing the first characteristic to determine the start and end of smoke extraction. Analysis of the monitored parameter may further include the steps of calculating a second characteristic of the monitored parameter and analyzing both the first and second characteristics to determine the start and end of smoke extraction. The start of smoke extraction may be determined if the first and second characteristics satisfy one or more predetermined conditions. Similarly, the end of smoke extraction may be determined if the first and second characteristics satisfy one or more predetermined conditions.

[0082] In a preferred embodiment, the first characteristic is a first moving average of the monitored parameter calculated on a first time window having a duration of the first time window. The second characteristic may be a second moving average of the monitored parameter calculated on a second time window having a duration of the second time window, where the duration of the second time window is different from that of the first time window. The onset of smoke inhalation may be determined when the first and second moving averages satisfy a predetermined relationship with respect to each other. A preferred method for detecting user smoke inhalation by monitoring the characteristics of a power signal is described in WO2022 / 003072, the contents of which are incorporated herein by reference in their entirety.

[0083] The apparatus preferably includes a power source, such as a rechargeable battery for supplying energy to heat the aerosol-forming substrate.

[0084] In some embodiments, the aerosol generator may further include a flow meter, for example, a flow meter for measuring the flow in the airflow path upstream of the cavity for receiving the aerosol-forming substrate. The use of a flow meter may be advantageous in development applications because it can enable effective calibration of the pressure sensor to optimize fume extraction detection for a particular combination of the device and substrate. A test system aerosol generator for setting or calibrating specific features such as the pressure sensor and optimizing features such as the dimensions of the flow limiter may be any aerosol generator described herein with a flow meter added upstream of the limiter. Such a test system may be particularly advantageous if the flow limiter of the test system is a variable flow limiter whose dimensions can be optimized, for example, for a particular aerosol-generating article. Subsequently, a commercial version of the aerosol generator may be manufactured with the desired settings, without requiring a flow meter.

[0085] Advantageously, the aerosol generator may be configured such that, upon use, it enters a standby mode in which an aerosol-forming substrate received within the device is heated, determining the start of a usage session, the temperature of the aerosol-forming substrate is controlled during the standby mode with reference to a standby target temperature, detects user inhalation during a usage session, and in response to the detected user inhalation, enters an operating mode in which greater thermal energy is supplied to the aerosol-forming substrate to raise its temperature, the temperature of the aerosol-forming substrate during the operating mode is controlled with reference to an operating target temperature higher than the standby target temperature.

[0086] The aerosol generator may include a housing. The housing may be elongated. The housing may contain any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of these materials, or thermoplastic resins suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably lightweight and non-brittle.

[0087] The device may include one or more power sources or power supplies, one or more heaters, and a control device. The control device may be configured to enter standby mode at the start of a usage session, detect the start of user inhalation, switch from standby mode to operating mode in response to the detection of the start of user inhalation, detect the end of user inhalation, and switch from operating mode to standby mode in response to the detection of the end of user inhalation.

[0088] The power source may be in the form of a battery. The battery may be rechargeable. The battery may be a lithium-based battery, such as a lithium cobalt battery, lithium iron phosphate battery, lithium titanate battery, or lithium polymer battery. The battery may be a nickel-metal hydride battery or a nickel-cadmium battery. The power source may be another form of charge storage device, such as a capacitor. The power source may be rechargeable and may be configured for numerous charge and discharge cycles. The power source may have a capacity that allows for the storage of sufficient energy for one or more user experiences of the aerosol generating system. For example, the power source may have a capacity that allows for continuous aerosol generation for about six minutes, or a multiple of six minutes, corresponding to the typical time it takes to smoke one conventional cigarette. In another embodiment, the power source may have a capacity that allows for a predetermined number of puffs or discontinuous operation of the aerosol generating system.

[0089] The control device or control circuit may be, or include, any suitable control device or electrical component. The control device may include memory. Information for carrying out the methods described above may be stored in memory. The control circuit may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, or an application-specific integrated circuit (ASIC) or other electronic circuit capable of providing control. The control circuit may be configured to supply power to the heating element continuously after the device has been operated, or to supply power intermittently, such as per smoke extraction. Power may be supplied to the heating element in the form of current pulses, for example by pulse width modulation (PWM). The control circuit may include further electronic components. For example, in some embodiments, the control circuit may include a sensor element, a switch element, or a display element. The control device may be configured to increase the power supplied to one or more heaters during operation mode compared to standby mode.

[0090] According to one aspect of the present invention, an aerosol generating system may be provided, comprising the above-described aerosol generating device and an aerosol generating article including an aerosol forming substrate. The aerosol generating article may be configured to be at least partially received within the aerosol forming device. The aerosol generating article may comprise a plurality of components, including an aerosol forming substrate assembled within a wrapper.

[0091] In some embodiments, the aerosol-generating article may have a draw-out resistance (RTD) of 10 mmH2O to 50 mmH2O.

[0092] An aerosol generating system may have a system airflow path defined through the device and the aerosol generating article when the aerosol generating article is received into the device. For example, the system airflow path may include an airflow path defined through the device and an airflow path defined through the aerosol generating article. The system airflow path may have a drawdown resistance (RTD) of 20 mmH2O to 100 mmH2O.

[0093] The article may look substantially similar to a conventional cigarette. The article may be in the form of a rod, or may have a rod-like or stick-like shape. The article may be substantially cylindrical, for example, a straight cylinder. The article may have a length of 30 mm to 120 mm, for example, 40 mm to 80 mm, for example, about 45 mm. The article may have a diameter of 3.5 mm to 10 mm, for example, 4 mm to 8.5 mm, for example, 4.5 mm to 7.5 mm.

[0094] The substrate may be substantially cylindrical, for example, a right cylinder. References in this specification are made to the inner and outer portions of the aerosol-forming substrate. The inner portion may be, or contain, the aerosol-forming material within the axial central portion of the aerosol-forming substrate, for example, the axial central cylindrical portion or the axial central right cylindrical portion. The outer portion may be, or contain, the aerosol-forming material within the axial outer portion of the aerosol-forming substrate. The outer portion may be cylindrical, for example, a right cylinder. The outer portion may have an annular cross-section, for example, a circular annular cross-section. There may be no aerosol-forming substrate between the inner and outer portions. The inner and outer portions may be in contact. The entirety of the aerosol-forming material of the aerosol-forming substrate may be found within the inner and outer portions.

[0095] Optionally, the article comprises a front plug. Optionally, the article comprises an aerosol-forming substrate. Optionally, the article comprises a first hollow tube, e.g., a first hollow acetate tube. Optionally, the article comprises a second hollow tube, e.g., a second hollow acetate tube. Optionally, the second hollow tube comprises one or more vents. Optionally, the article comprises a mouth-side plug filter. Optionally, the article comprises a wrapper, e.g., a paper wrapper. Optionally, one or more or all of the front plug, aerosol-forming substrate, first hollow tube, second hollow tube, and, if present, the mouth-side plug filter, are enclosed by the wrapper.

[0096] Optionally, a front plug is located at the upstream end of the article. Optionally, an aerosol-forming substrate is located downstream of the front plug. Optionally, a first hollow tube is located downstream of the aerosol-forming substrate. Optionally, a second hollow tube is located downstream of the first hollow tube. Optionally, a mouth-side plug filter is located downstream of one or both of the first and second hollow tubes. Optionally, the mouth-side plug filter is located at the downstream end of the article. Optionally, the downstream end of the article, which may also be referred to as the mouth end of the article, may be configured to be inserted into the user's mouth. The user may, for example, inhale directly from the mouth end of the article.

[0097] One or more of the front plug, aerosol-forming substrate, first hollow tube, second hollow tube, and mouth plug filter may be substantially cylindrical, for example, a straight cylindrical shape. One or more of the front plug, aerosol-forming substrate, first hollow tube, second hollow tube, and mouth plug filter may have a diameter of 3.5 mm to 10 mm. Optionally, the front plug may have a length of 2 to 10 mm. Optionally, the aerosol-forming substrate in the article may have a length of 5 to 20 mm. Optionally, the first hollow tube may have a length of 2 to 20 mm. Optionally, the second hollow tube may have a length of 2 to 20 mm. Optionally, the mouth plug filter may have a length of 5 to 20 mm.

[0098] The article may include a cartridge, or may be a cartridge. The cartridge may hold an aerosol-forming substrate. The cartridge may hold a susceptor. The cartridge may comprise a cartridge housing. One or both of the aerosol-forming substrate and the susceptor may be located within the cartridge housing.

[0099] The cartridge may have length, width, and thickness. The thickness may be less than 0.5 or 0.2 times the length, width, or both. In this case, the cartridge may be referred to as a flat or planar cartridge. The cartridge may be of any preferred shape and size, for example, substantially cylindrical or cubic. The cartridge may be any of the cartridges described in WO2015177043, the contents thereof incorporated herein.

[0100] The susceptor may have a susceptor length, a susceptor width, and a susceptor thickness. The susceptor thickness may be less than 0.5 or 0.2 times the susceptor length, susceptor width, or both. In this case, the susceptor may be referred to as a flat susceptor or a planar susceptor. The aerosol-forming substrate may have a substrate length, a substrate width, and a substrate thickness. The substrate thickness may be less than 0.5 or 0.2 times the substrate length, substrate width, or both. In this case, the aerosol-forming substrate may be referred to as a flat or planar aerosol-forming substrate.

[0101] The susceptor may form the inner surface of the cartridge housing, be mounted thereto, or be located adjacent to it. The susceptor element may be in contact with the aerosol-forming substrate. The susceptor heating element may be located between the aerosol-forming substrate and the inner surface. The largest or second largest surface of the susceptor may be in contact with, or adjacent to, the largest or second largest surface of the aerosol-forming substrate. This may be particularly advantageous when one or both of the susceptor and the aerosol-forming substrate are flat or planar. This may advantageously maximize heat transfer from the susceptor to the aerosol-forming substrate during use.

[0102] According to one aspect of the present invention, a method for generating an aerosol using an aerosol generator is provided, the aerosol generator comprising: a cavity for receiving at least a portion of an aerosol-forming substrate; an airflow path upstream of the cavity through which air can be drawn when a user uses the device, the airflow path connecting the cavity to an external environment; and a pressure sensor located in communication with the airflow path upstream of the cavity, the method comprising: disposing of an aerosol-forming substrate in the cavity; operating the device to operate according to a standby mode; detecting a pressure change in the airflow path associated with the start of user inhalation; switching the mode of operation from standby mode to operating mode in response to the detected start of user inhalation; detecting a pressure change in the airflow path associated with the end of user inhalation; and switching the mode of operation from operating mode to standby mode in response to the detected end of user inhalation.

[0103] According to one aspect of the present invention, a method for operating an aerosol using an aerosol generator is provided, the aerosol generator comprising: a cavity for receiving at least a portion of an aerosol-forming substrate; and an airflow path upstream of the cavity through which air can be drawn when a user uses the device, the airflow path connecting the cavity to an external environment, the steps of: arranging the aerosol-forming substrate in the cavity; operating the device to operate according to a standby mode in which the temperature of the aerosol-forming substrate is controlled with reference to a standby target temperature; and in response to user inhalation of smoke, switching the mode of operation from the standby mode to an operating mode in which the temperature of the aerosol-forming substrate is controlled with reference to an operating target temperature, wherein the operating target temperature is higher than the standby target temperature.

[0104] According to one aspect of the present invention, a method for generating an aerosol using an aerosol generator is provided, the aerosol generator comprising: a cavity for receiving at least a portion of an aerosol-forming substrate; and an airflow path upstream of the cavity through which air can be drawn when a user uses the device, the airflow path connecting the cavity to an external environment, the device further comprising: a first heater disposed in thermal contact with the cavity; and a second heater disposed in thermal contact with the airflow path upstream of the cavity, the method comprising: placing the aerosol-forming substrate in the cavity; operating the device to operate according to a standby mode in which the temperature of the aerosol-forming substrate is heated by the first heater to a standby target temperature; and drawing air through the airflow path, the air drawn through the airflow path being heated by the second heater, thereby raising the temperature of the aerosol-forming substrate from the standby target temperature to an operating target temperature higher than the standby target temperature.

[0105] The method for generating aerosols may involve any of the above-mentioned devices or systems.

[0106] As used herein, the terms “aerosol-generating article” or simply “article” may refer to an article that, for example, can generate or release aerosols when heated.

[0107] As used herein, the term "aerosol-forming substrate" may refer to a substrate having the ability to release aerosols or volatile compounds that can form aerosols. Such volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may comprise one or more aerosol-forming bodies or aerosol-forming materials. The aerosol-forming substrate may be adsorbed, coated, impregnated, or otherwise loaded onto a carrier or support. Conveniently, the aerosol-forming substrate may be part of an aerosol-generating article or a smoking article.

[0108] Optionally, the aerosol-forming substrate is a solid aerosol-forming substrate. However, the aerosol-forming substrate may contain both solid and liquid components. Alternatively, the aerosol-forming substrate may be a liquid aerosol-forming substrate.

[0109] Optionally, the aerosol-forming substrate may contain nicotine. Optionally, the aerosol-forming substrate may contain tobacco. Alternatively, or additionally, the aerosol-forming substrate may contain a non-tobacco-containing aerosol-forming material.

[0110] Optionally, the aerosol-forming substrate may include sheets of aerosol-forming material. For example, the aerosol-forming substrate may include sheets of homogenized tobacco material, such as an aggregate of crimped sheets of homogenized tobacco material.

[0111] As used herein, the term “aerosol-forming compound” may refer to any suitable known compound or mixture of compounds that facilitates aerosol formation during use and is substantially resistant to thermal decomposition at the operating temperature of the aerosol-generating article. Suitable aerosol-forming compounds are known in the art and include, but are not limited to, polyhydric alcohols (such as propylene glycol, triethylene glycol, 1,3-butanediol, and glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic acids, dicarboxylic acids, or polycarboxylic acids (such as dimethyl dodecanediate and dimethyl tetradecanediate). Preferred aerosol-forming compounds are polyhydric alcohols or mixtures thereof (such as propylene glycol, triethylene glycol, 1,3-butanediol, and most preferably glycerin). An aerosol-forming substrate may comprise one or more aerosol-forming compounds.

[0112] As used herein, the "aerosolization temperature" of an aerosol-forming substrate may refer to the lowest temperature at which the aerosol-forming substrate releases an aerosol or a volatile compound capable of forming an aerosol, or releases a substantial amount of a volatile compound capable of forming an aerosol.

[0113] As used herein, the term "usage session" may refer to a period of time during which a series of smoke extractions are applied by the user to extract aerosols from an aerosol-forming substrate.

[0114] As used herein, the term "aerosol generator" may refer to a device for use with an aerosol-generating article that enables the generation or release of aerosols.

[0115] As used herein, the term "susceptor" may refer to an element comprising a material having the ability to convert magnetic field energy into heat. When a susceptor is located in an alternating magnetic field, it may be heated. Depending on the electrical properties and magnetism of the susceptor material, the heating of the susceptor may result from at least one of hysteresis loss and eddy currents induced within the susceptor.

[0116] The terms “upstream” and “downstream” as used herein to refer to an aerosol generating article or aerosol generating device may be used to describe the relative position of a component or part of a component of an aerosol generating article or device with respect to the direction in which air flows through the aerosol generating article or device during its use. An aerosol generating article may have an upstream end through which air enters the article during use. An aerosol generating article may have a downstream end through which air or aerosol exits the article during use. An aerosol generating device may have an upstream end through which air enters the device during use. An aerosol generating article may have a downstream end through which air or aerosol exits the device during use. An aerosol generating system may be configured such that air enters the upstream end of an aerosol generating device, enters the upstream end of an aerosol generating article engaged with the device, and exits the downstream end of the aerosol generating article.

[0117] As used herein in connection with the present invention, the term "long axis direction" is used to describe the direction between the upstream and downstream ends of an aerosol generating article, and between the upstream and downstream ends of an aerosol generating device. During use, air is drawn through the aerosol generating article in the long axis direction.

[0118] As used herein in connection with the present invention, the term "length" is used to describe the maximum dimension in the longitudinal direction of an aerosol generating article or aerosol generating device, or a component of an aerosol generating article or aerosol generating device.

[0119] As used herein in connection with the present invention, the term “transverse direction” is used to describe a direction perpendicular to the longitudinal axis. Unless otherwise stated, when “cross section” of an aerosol generating article or aerosol generating device or a component of an aerosol generating article or aerosol generating device is referred to, it means a transverse section.

[0120] As used herein in connection with the present invention, the term "width" refers to the maximum dimension in the transverse direction of an aerosol generating article or apparatus or a component of an aerosol generating article or apparatus. For example, if an aerosol generating article has a substantially circular cross-section, the width of the aerosol generating article corresponds to the diameter of the aerosol generating article. If a component of the aerosol generating article has a substantially circular cross-section, the width of the component of the aerosol generating article corresponds substantially to the diameter of the component of the aerosol generating article.

[0121] As used herein, the term "heating element" refers to a component configured to transfer thermal energy to an aerosol generating substrate.

[0122] As used herein, the term "porous portion" refers to a portion of a body having multiple pores, at least a portion of which are interconnected. Thus, the porous portions of a body can substantially define airflow paths through them, allowing fluid to flow from one end face of the porous portion to a second end face of the porous portion opposite the first end face. Generally, the pressure drop across a porous portion will be greater than the pressure drop across a hollow tubular element of the same length and with a free cross-sectional area equal to the overall cross-sectional area of ​​the porous portion. Therefore, flow across a porous portion is generally partially restricted compared to flow through a hollow tubular element of comparable dimensions.

[0123] The term "porosity" of the main body generally refers to the ratio of the volume of accessible pores and voids to the bulk volume occupied by the main body. The term "cross-sectional porosity" refers to the fraction of voids in the cross-sectional area of ​​a porous body, for example, the cross-section of the porous portion of the heating element of the heater assembly according to the present invention. Cross-sectional porosity is the area ratio of void space in the cross-sectional area of ​​a porous body. The cross-sectional area of ​​a porous body is the area of ​​the porous body in a plane perpendicular to the longitudinal axis of the porous body, which is generally the longitudinal axis of the heater assembly and the longitudinal axis of the aerosol generator equipped with the heater assembly.

[0124] The porous body is typically substantially cylindrical, and thus the cross-sectional plane of the porous body is substantially circular. However, more generally, it is possible to identify the longitudinal axis of the porous body, and the cross-sectional plane of the porous body lies in a plane that is substantially perpendicular to the longitudinal axis.

[0125] As used herein, the term "electrically insulating" refers to a material having an electrical conductivity of less than 0.8 × 10 4 Siemens / meter, for example, in at least one direction, such as at room temperature (20 °C) and 50% relative humidity, and in all directions, at least 1 × 10 -4 , 5 × 10-4, or 1 × 10 -5 ohm-meter resistivity.

[0126] As used herein, the term "electrically resistive" refers to a material having an electrical conductivity of at least 0.8 × 10 6 Siemens / meter, for example, in at least one direction, such as at room temperature (20 degrees Celsius) and 50% relative humidity, and in all directions, 1 × 10 -4 , 5 × 10 -5 , or 1 × 10 -5 ohm-meter or less resistivity.

[0127] As used herein, the term "thermally conductive" refers to a material having a thermal conductivity of at least 5, 10, 20, 50, or 100 watts / meter kelvin, for example, in at least one direction, such as at room temperature (20 degrees Celsius) and 50% relative humidity, and in all directions.

[0128] Various references have been made to the scopes specified herein, such as temperature ranges. To avoid doubt, unless otherwise specified, any scope referred to herein may have only an upper limit, only a lower limit, or both an upper and lower limit. Limits to a temperature range, for example, any one or more arbitrary upper or lower limits to a temperature range for a heating zone, heater, or susceptor as described above, may be predetermined. The limits may be stored in the control unit or in memory, for example, in the memory of the control unit. The limits may be stored as temperature values, or in another form indicating temperature values, for example, as the electrical resistance value of the component to which the temperature range applies. In this case, the electrical resistance of the component may be monitored, rather than the temperature of the component, and may be compared to a temperature-versus-electrical resistance dataset to estimate the temperature of the component.

[0129] The present invention is defined in the claims. However, a non-exclusive list of non-limiting embodiments is provided below. One or more features of these embodiments may be combined with one or more features of other embodiments, forms, or aspects described herein. [Examples]

[0130] A non-exclusive list of non-limiting embodiments is provided below. One or more features of these embodiments may be combined with one or more features of other embodiments, or forms, or aspects described herein.

[0131] Example i. An aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, wherein the device is configured to heat the aerosol-forming substrate to a standby temperature during a usage session, and the device is configured such that the temperature of the aerosol-forming substrate rises from the standby temperature when a user inhales smoke. Example ii. The aerosol generator according to Example i, wherein the device is configured to supply a thermal boost to the aerosol-forming substrate during user smoke inhalation performed during a user session. Example iii. The aerosol generator according to Example i or Example ii, wherein the apparatus is configured to heat the aerosol-forming substrate during a usage session according to a standby mode or an operating mode, the temperature of the aerosol-forming substrate being controlled with reference to a standby target temperature during standby mode, and the temperature of the aerosol-forming substrate being controlled with reference to an operating target temperature during operating mode, the standby target temperature being higher than room temperature, and the operating target temperature being higher than the standby target temperature. Example iv. The aerosol generator according to Example III, wherein the device changes from standby mode to operating mode when the user starts inhaling smoke, and from operating mode to standby mode when the user stops inhaling smoke. Example v. The aerosol generator according to any one of Examples i to iv, wherein the apparatus is configured to heat the aerosol-forming substrate during a usage session according to a standby mode or an operating mode, the temperature of the aerosol-forming substrate is controlled with reference to a standby target temperature during standby mode, and the temperature of the aerosol-forming substrate is controlled with reference to an operating target temperature during operating mode, the standby target temperature being higher than room temperature, and the operating target temperature being higher than the standby target temperature. Example 1. An aerosol generator configured to generate aerosols from an aerosol-forming substrate, The device defines a cavity for receiving at least a portion of an aerosol-forming substrate, and an airflow path upstream of the cavity through which the user can draw air when using the device, the airflow path connecting the cavity to the external environment, and the device, An aerosol generator according to any of Examples i to v, for example, comprising a first heating portion located in a cavity and a second heating portion located in thermal contact with an airflow path upstream of the cavity. Example 2. The aerosol generator according to Example 1, wherein the first heating section includes a heater disposed to at least partially surround the cavity. Example 3. The aerosol generator according to Example 1 or Example 2, wherein the first heating section comprises a heater disposed in contact with the wall of the cavity, for example, a resistance heater disposed in contact with the wall of the cavity. Example 4. The aerosol generator according to Example 3, wherein the first heating portion comprises a flexible heater disposed in contact with the inner or outer surface of the cavity, for example, a polyimide flexible heater disposed in contact with the inner or outer wall of the cavity. Example 5. The aerosol generator according to any one of Examples i to 4, wherein the first heating portion comprises a heater located within a cavity, for example, a protruding heater configured to penetrate an aerosol-forming substrate inserted into the cavity. Example 6. The aerosol generator according to any one of embodiments i to 5, wherein the first heating portion comprises an induction heating device, for example, the first heating portion comprises an inductor located outside the cavity configured to heat a susceptor located inside the cavity or a susceptor that contacts or forms part of the cavity wall. Example 7. The aerosol generator according to Example 6, wherein the cavity wall contains or is formed from a susceptor material. Example 8. The aerosol generator according to any one of Examples i to 7, wherein the first heating portion is configured to directly heat the aerosol-forming substrate received in the cavity. Example 9. The aerosol generator according to any one of Examples i to 8, wherein the cavity is provided with an air intake that connects the cavity to an airflow path upstream of the cavity. Example 10. The aerosol generator according to any of Examples i to 9, wherein the second heating section is located in the airflow path upstream of the cavity. Example 11. The aerosol generator according to any one of Examples i to 10, wherein the second heating section comprises a heater located in the airflow path upstream of the cavity, for example, a resistance heater located in the airflow path upstream of the cavity. Example 12. The aerosol generating article according to any of Examples i to 11, wherein the second heating portion comprises an induction heating device, for example, the second heating portion comprises an inductor configured to heat a susceptor located in an airflow path upstream of the cavity. Example 13. The aerosol generating article according to any of Examples i to 12, wherein the second heating portion comprises a porous body, and an airflow path is defined through the porous body, preferably the airflow path through the second heating portion has a predetermined drawdown resistance (RTD). Example 14. The second heating section is an aerosol generating article according to any of Examples i to 13, comprising a heat exchanger. Example 14A. An aerosol generator according to any of Examples i to 14, wherein the first heating portion is formed by a cylindrical or tubular element made of a resistant material, and the second heating portion is formed as a permeable body, for example as a porous body, inside a portion of the cylindrical or tubular element, for example, inside the end of the cylindrical or tubular element opposite to the open end for receiving an aerosol-forming substrate, and the free space such as a cavity in the permeable body forms an airflow path. Example 14B. The aerosol generator according to any of Examples i to 14A, wherein the first heating portion is formed by a cylindrical or tubular element made of a resistant material, and the second heating portion is formed as a permeable body that defines an airflow path, for example, an airflow path formed by a plurality of tubular or meandering structures, inside a portion of the cylindrical or tubular element, for example, inside a portion of the cylindrical or tubular element opposite an open end for receiving an aerosol-forming substrate, and the plurality of tubular or meandering structures inside the permeable body form the airflow path. Example 14C. The aerosol generator according to any of Examples 1 to 14B, wherein the first heating portion and the second heating portion are formed as a single structure of heater material having the same electrical resistance. Example 15. The aerosol generating article according to any of Examples i to 14C, comprising a heating element configured for resistance heating, which may be referred to as Joule heating, wherein the heating element comprises a polymer composite material comprising a polymer matrix and a plurality of conductive particles dispersed within the polymer matrix. Example 16. The polymer composite material comprises a polymer matrix and a plurality of nonmetallic conductive particles dispersed within the polymer matrix, wherein the plurality of nonmetallic conductive particles include, for example, one or more of a plurality of carbon particles such as graphite particles and a plurality of boron nitride particles such as hexagonal boron nitride particles, according to Example 15. Example 17. The aerosol generator according to Example 15 or Example 16, wherein the polymer matrix comprises at least one of polyether ether ketone (PEEK) and liquid crystal polymer (LCP). Example 18. The aerosol generator according to any one of Examples 15 to 17, wherein the polymer matrix accounts for 22 to 33 weight percent of the thermally conductive elements. Example 19. The aerosol generator according to any one of Examples 15 to 18, wherein the plurality of nonmetallic conductive particles include at least one of expanded graphite particles and graphite nanoplatelets. Example 20. The aerosol generator according to any one of Examples 15 to 19, wherein nonmetallic conductive particles constitute 62 to 69 weight percent of the polymer composite material. Example 21. The polymer composite further comprises at least one additive dispersed in a polymer matrix, for example, at least one additive being carbon black, or containing carbon black, as described in any of Examples 15 to 20. Example 22. The heating element is formed by sintering polymer composite particles, and the aerosol generator is as described in any of Examples 15 to 21. Example 23. The heating element is an aerosol generator according to any one of Examples 15 to 22, having a total pore volume of less than 5 cubic centimeters. Example 24. An aerosol generator according to any of Examples 15 to 23, wherein the total pore volume of the heating element is at least 0.5 cubic centimeters. Example 25. An aerosol generator according to any of Examples 15 to 24, wherein the RTD of the heating element is greater than 10 milliliters of H2O. Example 26. The aerosol generator according to any of Examples 15 to 25, wherein the RTD of the heating element is less than 40 mmH2O. Example 27. The aerosol generator according to any of Examples 15 to 26, wherein the second heating portion comprises an inductor coil extending around at least a portion of the heating body, and for example, a power supply and control device are connected to the inductor coil and configured to supply a changing current to the inductor coil so that the inductor coil generates a changing magnetic field when in use. Example 28. The aerosol generator according to Example 27, wherein the inductor coil is positioned in direct contact with the outer surface of the heating element. Example 29. The aerosol generator according to any one of Examples i to 28, wherein the device is configured to generate an aerosol from an aerosol-forming substrate during a usage session having a usage session start and a usage session end. Example 30. The aerosol generator according to Example 29, wherein the device is configured to distinguish between smoke inhalation periods and non-smoke inhalation periods, the smoke inhalation period being defined as any period during a use session in which the user is actively inhaling smoke, and the non-smoke inhalation period being defined as any period during a use session in which the user is not actively inhaling smoke. Example 31. The apparatus is configured to heat an aerosol-forming substrate during a usage session with reference to two different target temperatures, a standby target temperature and an operating target temperature, wherein the standby target temperature is higher than room temperature and the operating target temperature is higher than the standby target temperature, as described in any of Examples i to 30. Example 32. An aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, wherein the device is configured to heat the aerosol-forming substrate during a usage session with reference to two different target temperatures, a standby target temperature and an operating target temperature, wherein the standby target temperature is higher than room temperature and the operating target temperature is higher than the standby target temperature, and the device is configured to heat the aerosol-forming substrate to the standby temperature during a usage session, and the device is further configured to heat the aerosol-forming substrate from the standby target temperature to the operating target temperature during user smoke extraction performed during a usage session, and the aerosol-forming substrate is made coolable from the operating target temperature after the user smoke extraction is completed, as described in any of Examples i to 31. Example 33. The aerosol generator according to Example 32, wherein a first heating section is configured to supply energy to heat the aerosol-forming substrate to a standby temperature, and a second heating section is configured to heat the aerosol-forming substrate to an operating temperature during user smoke extraction. Example 34. An aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, wherein both a first heating section and a second heating section are activated at the start of the usage session, the first heating section is configured to directly heat an aerosol-forming substrate received in a cavity, and the second heating section is configured to heat air drawn into the airflow path by user suction, as described in any of Examples i to 33. Example 35. An aerosol generator according to any of Examples i to 34, configured to detect user smoke inhalation. Example 35A. The aerosol generator according to Example 35, wherein power is supplied to the second heating section only while the user is inhaling smoke. Example 35B. The aerosol generator according to Example 35, wherein the power supplied to the second heating section is increased during the user's smoke inhalation. Example 36. An aerosol generator according to any one of embodiments i to 35, further comprising an airflow detector for detecting user smoke inhalation, for example, a pressure sensor located in the airflow path, for example, in the airflow path upstream of a cavity. Example 37. An aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, for example, an aerosol generator according to any of Examples i to 36, wherein the device is configured to heat the aerosol-forming substrate during a usage session with reference to two different target temperatures, a standby target temperature and an operating target temperature, wherein the standby target temperature is higher than room temperature and the operating target temperature is higher than the standby target temperature, and the device is configured to heat the aerosol-forming substrate to the standby temperature during a usage session, and the device is further configured to heat the aerosol-forming substrate from the standby target temperature to the operating target temperature during user smoke extraction performed during a usage session, and the aerosol-forming substrate is made coolable from the operating target temperature after the user smoke extraction is completed. Example 38. The aerosol generator according to any of Examples i to 37, wherein the standby target temperature is too low to release substantial aerosols from the aerosol-forming substrate. Example 39. The aerosol generator according to any of Examples i to 38, wherein the standby target temperature is lower than the effective boiling point of the aerosol-forming body or a mixture of aerosol-forming bodies of the aerosol-forming substrate, for example, lower than the boiling point of propylene glycol, or lower than the boiling point of glycerol, or lower than the boiling point of a specific mixture of propylene glycol and glycerol used as an aerosol-forming body in the aerosol-forming substrate. Example 40. The aerosol generator according to any of Examples i to 39, wherein the standby target temperature is less than 250°C, for example less than 230°C, for example less than 210°C, preferably less than 200°C, for example less than 180°C, or less than 160°C. Example 41. The aerosol generator according to any of Examples i to 40, wherein the standby target temperature is 50°C to 250°C, for example, 80°C to 200°C, for example, 100°C to 180°C. Example 42. The aerosol generator according to any of Examples i to 41, wherein the target operating temperature is a temperature sufficiently high to release aerosols from the aerosol-forming substrate. Example 43. The aerosol generator according to any of Examples i to 42, wherein the target operating temperature is higher than the effective boiling point of the aerosol-forming body or mixture of aerosol-forming bodies of the aerosol-forming substrate, for example, higher than the boiling point of propylene glycol, or higher than the boiling point of glycerol, or higher than the boiling point of a specific mixture of propylene glycol and glycerol used as the aerosol-forming body in the aerosol-forming substrate. Example 44. An aerosol generator according to any of Examples i to 43, wherein the target operating temperature is above 160°C, for example above 180°C, or above 200°C, or above 250°C, for example above 280°C, or above 300°C, or above 320°C, or above 340°C. Example 45. The aerosol generator according to any of Examples i to 44, wherein the target operating temperature is 160°C to 400°C, for example, 180°C to 340°C, for example, 220°C to 300°C. Example 46. An aerosol generator according to any of Examples i to 45, wherein the standby target temperature is constant throughout the entire duration of the usage session. Example 47. The aerosol generator according to any of Examples i to 46, wherein the standby target temperature changes over the duration of the usage session. Example 48. An aerosol generator according to any of Examples i to 47, wherein the target operating temperature is constant throughout the entire duration of the usage session. Example 49. The operating target temperature changes over the duration of the usage session, for example, the operating target temperature changes with each smoke extraction, as described in any of Examples i to 48. Example 50. An aerosol generator according to any of Examples i to 49, wherein the usage session has a start and an end to the usage session, and the aerosol-forming substrate is heated to a standby target temperature at the start of the usage session and maintained above the standby target temperature for the duration of the usage session until the end of the usage session. Example 51. An aerosol generator according to any one of Examples i to 50, wherein a usage session is defined between the start and end of a usage session, a smoke absorption period is defined as any period during a usage session in which the user is actively smoke-absorbing, a non-smoke absorption period is defined as any period during a usage session in which the user is not actively smoke-absorbing, and the temperature of the aerosol-forming substrate is controlled with respect to the operating target temperature during the smoke absorption period, with reference to the standby target temperature during the non-smoke absorption period. Example 52. The aerosol generator according to Example 51, wherein each of the one or more smoke inhalations performed during a usage session has a smoke inhalation start and a smoke inhalation end, and the period between the smoke inhalation start and the smoke inhalation end is the smoke inhalation period. Example 53. An aerosol generator according to any of Examples i to 52, wherein the usage session has a usage session duration, for example, a predetermined duration set by referring to time, or by referring to usage parameters, or by referring to both time and usage parameters. Example 54. The aerosol generator according to Example 53, wherein the parameters used are selected from a list consisting of the number of user inhalations performed during the usage session, the volume of aerosols generated during the usage session, and the power supplied to the heater during the usage session. Example 55. The aerosol generator according to any of Examples i to 54, wherein the device is configured to detect one or more user smoking incidents that occur during a usage session. Example 56. The aerosol generator according to any of Examples i to 55, wherein the device is configured to distinguish between smoke inhalation periods and non-smoke inhalation periods, the smoke inhalation period being defined as any period during a use session in which the user is actively inhaling smoke, and the non-smoke inhalation period being defined as any period during a use session in which the user is not actively inhaling smoke. Example 57. The aerosol generator according to any of Examples i to 56, wherein the device is configured to detect user inhalation performed during a usage session, for example, the initiation of each user inhalation performed during a usage session. Example 58. The aerosol generator according to any of Examples i to 57, wherein the device is configured to detect user inhalation performed during a usage session, for example, the end of each user inhalation performed during a usage session. Example 59. The aerosol generator according to any of Examples i to 58, wherein the apparatus is configured to determine the duration of user inhalation performed during a usage session, for example, the duration of each user inhalation performed during a usage session. Example 60. The apparatus is configured to characterize user smoke inhalation performed during a usage session, for example, each smoke inhalation performed during a usage session, as described in any of Examples i to 59. Example 61. An aerosol generator according to Example 60, configured to characterize detected user inhalation performed during a usage session, for example, each detected user inhalation performed during a usage session. Example 62. The aerosol generator according to Example 60 or Example 61, configured to determine the volume of aerosols generated during user inhalation performed during a usage session, for example, during each user inhalation performed during a usage session. Example 63. The aerosol generator according to any of Examples i to 62, comprising a pressure sensor for use in detecting one or more user smoke inhalations performed during a usage session. Example 64. The aerosol generator according to Example 63, wherein a pressure sensor detects a change in pressure in the airflow path as a result of the user performing smoke extraction, for example, smoke extraction involves the user drawing air through a portion of the device along the airflow path, and the pressure sensor detects a change in pressure in the airflow path as a result of the user performing smoke extraction. Example 65. The aerosol generator according to any of Examples i to 64, comprising a cavity for receiving at least a portion of an aerosol-forming substrate, and an upstream airflow path of the cavity through which a user can draw air when the device is in use, wherein the airflow path connects the cavity to the external environment. Example 66. The aerosol generator according to Example 65, wherein the airflow path upstream of the cavity acts as a flow limiter, or is equipped with a flow limiter. Example 67. The aerosol generator according to Example 66 comprises a flow limiter, which is a mechanical element located in the airflow path, such as an orifice plate located in the airflow path. Example 68. The flow limiter is a variable flow limiter, for example, the flow limiter is an adjustable valve, in the aerosol generator according to Example 66. Example 69. A portion of the airflow path upstream of the cavity is 3 mm 2 Less than, for example, 2mm 2 Less than 1.5 mm 2 Less than 1 mm 2 An aerosol generator according to any one of Examples 66 to 68, having a cross-sectional area less than [amount missing]. Example 70. The aerosol generator according to any one of Examples 66 to 69, wherein the airflow path upstream of the cavity has a drawdown resistance (RTD) greater than 10 mmH2O, for example, 10 mmH2O to 50 mmH2O. Example 70A. The aerosol generator according to any of Examples i to 70, wherein the pressure sensor is located upstream of the cavity but downstream of the flow limiter. Example 70B. The aerosol generator according to Example 70A comprises an airflow path upstream of the cavity, a flow limiter, and an expansion zone downstream of the flow limiter, and a pressure sensor located in the expansion zone. Example 70C. The aerosol generator according to Example 70B, wherein the airflow path upstream of the expansion zone has a draw-out resistance (RTD) greater than 10 mmH2O, for example, greater than 20 H2O or greater than 30 H2O, preferably 10 mmH2O to 50 mmH2O, and for example, a portion of the airflow path equipped with a flow limiter provides a draw-out resistance (RTD) of 10 mmH2O to 50 mmH2O. Example 71. The aerosol generator according to any of Examples i to 70C, wherein the device is configured to monitor parameters indicating aerosol generation during the operation of the aerosol generator and to use the monitored parameters in the detection of one or more user smokings that occurred during a usage session. Example 72. The monitored parameters are analyzed to identify user inhalation, and user inhalation is defined by the inhalation start and inhalation end, in the aerosol generator according to Example 71. Example 73. The monitored parameter represents the power supplied by the power source, in the aerosol generator according to Example 71 or Example 72. Example 74. The aerosol generator according to any one of Examples 72 to 73, comprising the steps of: calculating a first characteristic of the monitored parameter; and analyzing the first characteristic to determine the start and stop of smoke extraction. Example 75. The aerosol generator according to Example 74, wherein the analysis of the monitored parameters includes the steps of calculating a second characteristic of the monitored parameters and analyzing both the first and second characteristics to determine the start and stop of smoke extraction. Example 76. The aerosol generator according to Example 75, wherein the start of smoke extraction is determined when the first and second characteristics satisfy one or more predetermined conditions. Example 77. The aerosol generator according to Example 76, wherein the termination of smoke extraction is determined when the first and second characteristics satisfy one or more predetermined conditions. Example 78. The first characteristic is a first moving average of the monitored parameter calculated on a first time window having a first time window duration, according to any of Examples 74 to 77. Example 79. The second characteristic is a second moving average of the monitored parameter calculated on a second time window having a second time window duration, wherein the duration of the second time window is different from the duration of the first time window, as described in any of Examples 74 to 78. Example 80. The aerosol generator according to Example 79, wherein the start of smoke extraction is determined when the first moving average value and the second moving average value satisfy a predetermined relationship with respect to each other. Example 81. The apparatus is an aerosol generator according to any of Examples i to 80, which defines an airflow path through which a user can draw air when using the apparatus. Example 82. The aerosol generator according to any one of Examples i to 81, wherein the apparatus defines a cavity having an opening for receiving at least a portion of an aerosol-forming substrate. Example 83. The aerosol generator according to Example 82, wherein the device defines an upstream airflow path of a cavity through which a user can draw air when the device is in use, and the airflow path connects the cavity to the external environment. Example 84. The apparatus is an aerosol generator according to any of Examples i to 83, which is equipped with a power supply. Example 85. The apparatus is an aerosol generator according to any of Examples i to 84, comprising a heater for heating an aerosol-forming substrate. Example 86. The aerosol generating apparatus according to any one of Examples i to 85, comprising a heater for heating the external portion of the aerosol-forming substrate, for example, a heater that surrounds or partially surrounds a portion of the aerosol-forming substrate received within the apparatus. Example 87. The aerosol generating apparatus according to any one of Examples i to 86, comprising a heater for heating the internal portion of the aerosol-forming substrate, for example, a heater that can be inserted into a portion of the aerosol-forming substrate received in the apparatus. Example 88. The aerosol generator according to any one of Examples i to 87, comprising a heater for heating air in an airflow path upstream of an aerosol-forming substrate, for example, a heater for heating air drawn into the apparatus so that the heated air acts to heat the aerosol-forming substrate received into the apparatus. Example 89. The aerosol generator according to any one of Examples i to 88, comprising a control device for controlling the generation of aerosols, for example, a control device that communicates with a power supply and a heater. Example 90. The aerosol generator according to any one of Examples i to 89, comprising a resistance heater disposed to heat an aerosol-forming substrate received in a cavity of the apparatus. Example 91. The aerosol generator according to any one of Examples i to 90, comprising an induction heater disposed to heat an aerosol-forming substrate received in a cavity of the apparatus, for example, the apparatus comprising an inductor disposed to heat a susceptor that is in thermal communication with the aerosol-forming substrate received in a cavity of the apparatus. Example 92. The apparatus is an aerosol generator according to any of Examples i to 91, configured to determine the temperature of the aerosol-forming substrate during use. Example 93. The aerosol generator according to any of Examples i to 92, comprising a control device configured to determine the temperature of an aerosol-forming substrate in use, wherein the temperature is determined by monitoring the behavior of a heater in use, for example, by monitoring the apparent resistance or apparent conductance of the heater. Example 94. The aerosol generator according to any of Examples i to 93, comprising a sensor configured to determine the temperature of the aerosol-forming substrate during use, such as a positive temperature coefficient (PTC) sensor, a thermocouple, a thermal switch, or any other optional temperature control element. Example 95. The aerosol generator according to any of Examples i to 94 further comprises a flow meter, for example, a flow meter for measuring the flow in an airflow path upstream of a cavity for receiving an aerosol-forming substrate. Example 96. The device enters a standby mode during use, in which the aerosol-forming substrate received within the device is heated, and the temperature of the aerosol-forming substrate is controlled during the standby mode with reference to a standby target temperature. An aerosol generator according to any of Examples i to 95, configured to detect user inhalation during a usage session and, in response to the detected user inhalation, enter an operating mode in which greater thermal energy is supplied to the aerosol-forming substrate to raise the temperature of the aerosol-forming substrate, wherein the temperature of the aerosol-forming substrate during the operating mode is controlled to reference an operating target temperature higher than the standby target temperature. Example 97. The device comprises one or more power supplies, one or more heaters, and a control device, the control device being Enters standby mode at the start of a session, detects when the user begins smoking, The aerosol generator according to Example 96, configured to switch from standby mode to operating mode in response to detection of the start of user smoke inhalation, to detect the end of user smoke inhalation, and to switch from operating mode to standby mode in response to detection of the end of user smoke inhalation. Example 98. The aerosol generator according to Example 96 or Example 97, wherein the control device increases the power supplied to one or more heaters during operation mode compared to standby mode. Example 99. The aerosol generator according to any one of Examples 96 to 98, comprising a first heater and a second heater, wherein the first heater is arranged to heat an aerosol-forming substrate during standby mode, and the second heater is not arranged to heat an aerosol-forming substrate during standby mode. Example 100. The aerosol generator according to any one of Examples 96 to 99, comprising a first heater and a second heater, both of which are arranged to heat an aerosol-forming substrate during operation. Example 101. An aerosol generator according to any of Examples 99 to 100, wherein a first heater is arranged to operate during a usage session, and a second heater is arranged to operate during user inhalation, for example, the second heater is switched on only during user inhalation, or the power supplied to the second heater is increased during user inhalation. Example 102. An aerosol generating system comprising an aerosol generating device described in any of Examples i to 101 and an aerosol generating article containing an aerosol forming substrate, wherein the aerosol generating article is configured to be at least partially received within the aerosol forming device. Example 103. The aerosol generating system according to Example 102 comprises a plurality of components, including an aerosol-forming substrate assembled within a wrapper, for the aerosol-forming article. Example 104. The aerosol generating article is an aerosol generating system according to either Example 102 or Example 103, having a drawdown resistance (RTD) of 10 mmH2O to 50 mmH2O. Example 105. The system airflow path is defined through the apparatus and the aerosol generating article when the aerosol generating article is received into the apparatus, for example, the system airflow path includes an airflow path defined through the apparatus and an airflow path defined through the aerosol generating article, for example, the system airflow path having a drawdown resistance (RTD) of 20 mmH2O to 100 mmH2O, as described in the aerosol generating system of Example 102 or Example 103. Example 106. A method for generating an aerosol using an aerosol generator, wherein the aerosol generator comprises a cavity for receiving at least a portion of an aerosol-forming substrate, and an airflow path upstream of the cavity through which a user can draw air when using the device, the airflow path connecting the cavity to the external environment. A pressure sensor located in communication with the airflow path upstream of the cavity, and a step of arranging an aerosol-forming substrate inside the cavity, A method comprising the steps of: activating the device to operate according to a standby mode; detecting a pressure change in an airflow path associated with the initiation of user smoke inhalation; switching the mode of operation from standby mode to operating mode in response to the detected initiation of user smoke inhalation; detecting a pressure change in an airflow path associated with the termination of user smoke inhalation; and switching the mode of operation from operating mode to standby mode in response to the detected termination of user smoke inhalation. Example 107. A method for operating an aerosol using an aerosol generator, the aerosol generator comprising: a cavity for receiving at least a portion of an aerosol-forming substrate; an upstream airflow path of the cavity through which a user can draw air when the device is in use, and an airflow path connecting the cavity to an external environment, the method comprising: placing the aerosol-forming substrate in the cavity; operating the device to operate according to a standby mode in which the temperature of the aerosol-forming substrate is controlled with reference to a standby target temperature; and in response to user inhalation of smoke, switching the mode of operation from the standby mode to an operating mode in which the temperature of the aerosol-forming substrate is controlled with reference to an operating target temperature, wherein the operating target temperature is higher than the standby target temperature. Example 108. A method for generating an aerosol using an aerosol generator, the aerosol generator comprising: a cavity for receiving at least a portion of an aerosol-forming substrate; an airflow path upstream of the cavity through which a user can draw air when the device is in use, and an airflow path connecting the cavity to the external environment, the device further comprising: a first heater disposed in thermal contact with the cavity; and a second heater disposed in thermal contact with the airflow path upstream of the cavity. A method comprising the steps of: placing an aerosol-forming substrate in a cavity; operating the apparatus to operate according to a standby mode in which the temperature of the aerosol-forming substrate is heated to a standby target temperature by a first heater; and drawing air through an airflow path, wherein the air drawn through the airflow path is heated by a second heater, and the temperature of the aerosol-forming substrate is raised from the standby target temperature to an operating target temperature higher than the standby target temperature. Example 109. A method for generating the aerosol described in Example 106, Example 107, or Example 108, using an apparatus defined in any of Examples i to 101, or a system defined in any of Examples 102 to 105.

[0132] The present invention will be further described, for illustrative purposes only, with reference to the attached drawings. [Brief explanation of the drawing]

[0133] [Figure 1] Figure 1 shows a schematic cross-sectional view of a portion of the aerosol generator. [Figure 2] Figure 2 shows the aerosol generator from Figure 1 engaged with an aerosol generating article. [Figure 3] Figure 3 is a time / temperature plot showing the heating profile applied to the aerosol-forming substrate using the apparatus shown in Figure 1. [Figure 4] Figure 4 shows a schematic cross-sectional view of a portion of an aerosol generator according to one embodiment of the present invention, which shows a pressure sensor located within the airflow path. [Figure 5]Figure 5 shows a schematic cross-sectional view of a portion of a further aerosol generator according to one embodiment of the present invention, showing a pressure sensor located within the airflow path. [Figure 6] Figure 6 shows a schematic cross-sectional view of a portion of an aerosol generator according to an embodiment of the present invention, configured as a test apparatus having an additional flow meter. [Figure 7] Figure 7 shows a schematic diagram of a heater assembly for use in an aerosol generator according to an embodiment of the present invention. [Figure 8] Figure 8 shows a schematic cross-sectional view of a portion of a further aerosol generator according to one embodiment of the present invention, which includes the heater assembly shown in Figure 7. [Figure 9] Figure 9 shows a schematic diagram of a further heater assembly for use in an aerosol generator according to an embodiment of the present invention. [Figure 10] Figure 10 shows a schematic diagram of a further aerosol generating device according to an embodiment of the present invention, engaged with an aerosol generating article. [Figure 11] Figure 11 shows a schematic cross-sectional view of a further heater assembly for use in an aerosol generator according to an embodiment of the present invention. [Figure 12] Figure 12 shows a schematic end cross-sectional view of the heater assembly shown in Figure 11. [Figure 13] Figure 13 shows a schematic cross-sectional view of a further heater assembly for use in an aerosol generator according to an embodiment of the present invention. [Figure 14] Figure 14 shows a schematic end cross-sectional view of the heater assembly shown in Figure 13. [Figure 15] Figure 15 shows a schematic cross-sectional view of a further heater assembly for use in an aerosol generator according to an embodiment of the present invention. [Figure 16] Figure 16 shows a schematic end cross-sectional view of the heater assembly shown in Figure 15. [Modes for carrying out the invention]

[0134] Figure 1 is a schematic cross-sectional view showing a portion of the aerosol generator 1. The device 1 includes an open end 12 through which a portion of an aerosol generating article can be inserted into a heating chamber 2. Alternatively, the heating chamber 2, which may be called a heating cavity, is sized to receive a portion of a rod-shaped aerosol generating article. The chamber 2 is defined by a wall 11 extending along its long axis, and a first heater 3 surrounds the wall 11 and provides thermal energy to heat the chamber 2 and any contents within the chamber. In one exemplary embodiment, the first heater is a resistance heater. The device defines an airflow path 6 leading from the inlet of the device to the chamber 2. A second heater 4 is located in the airflow path 6 upstream of the chamber 2. The second heater 4 is arranged to heat the air drawn into the chamber 2 through the airflow path 6. The second heater 4 may provide a large heating surface area to efficiently heat the air passing through it. For example, the second heater 4 may comprise a plurality of heater plates 5 through which air is drawn. The second heater may include a highly porous heater body that acts as a heat exchanger.

[0135] Chamber 2, first heater 3, second heater 4, and airflow path 6 are located within the housing 77. The housing also includes a power source, such as a battery, and a control device arranged to control the power supply from the power source to the first and second heaters. Although the battery and control device are not shown in Figure 1, the arrangement of such components within the housing of an aerosol generator is well known.

[0136] Figure 2 shows the same part of the aerosol generator shown in Figure 1 with the aerosol generating article 200 inserted into the chamber. The exemplary aerosol generating article 200 shown in Figure 2 comprises an aerosol-forming substrate 201 formed from an aggregate of homogenized tobacco sheets, a hollow acetate tube 202 located immediately downstream of the aerosol-forming substrate, a free-flow filter (wide-perforated tube) 203 located downstream of the hollow acetate tube, and a mouthpiece filter 204 located downstream of the free-flow filter. These components are arranged within a wrapper 205, for example, within a cigarette paper wrapper. This typical aerosol generating article 200 resembles a conventional cigarette. The front end, or distal portion, of the aerosol generating article 200 is inserted into the chamber 2 of the aerosol generator 1 so that the aerosol-forming substrate 201 is located within the chamber 2 when in use. The mouth end or proximal end of the aerosol-generating article protrudes from the chamber 2, thereby allowing the user to inhale through the mouth end of the article 200. When the user inhales through the mouth end of the article 200 located inside the chamber 3, air is drawn into the inlet of the device, through the airflow path 6, through the second heater 4, into the chamber 2, through the aerosol-forming substrate 201 of the article 200, and into the user's mouth. If the aerosol-forming substrate is heated above its aerosolization temperature, the volatile components of the aerosol-forming substrate may volatilize. These volatilized components may be carried in the airflow as they condense when inhaled by the user with the article, forming an inhalable aerosol that is consumed by the user.

[0137] In an exemplary use, an aerosol-generating article may be consumed during a use session using a dual heating mode regime. A chart illustrating such a heating profile is provided as Figure 3. When the article 200 is inserted into the chamber 2 of the apparatus and a use session is initiated, the control unit activates the first heater to heat the aerosol-forming substrate and controls the temperature of the aerosol-forming substrate to a standby target temperature 310. The standby target temperature 310 is a temperature below the aerosolization temperature of the aerosol-forming substrate. That is, the standby temperature is lower than the temperature at which a significant amount of the volatile components of the aerosol-forming substrate volatilize, and therefore lower than the temperature at which aerosols can be formed. Preferably, the standby target temperature is only slightly below the aerosolization temperature of the substrate. For example, the standby target temperature may be 170°C, in which case the temperature of the substrate is raised from the ambient temperature to the standby target temperature during the heating phase 311. Once the substrate reaches the standby target temperature, the power supply to the first heater is controlled to maintain the temperature of the substrate at the standby target temperature. Therefore, the standby target temperature may be called the maintenance temperature, and the first heater may be called the maintenance heater.

[0138] The temperature of the aerosol-forming substrate can be measured directly with a temperature sensor. Alternatively, the substrate temperature can be determined by monitoring the electrical parameters of the heater, such as the heater's resistance or the power supplied to the heater.

[0139] The second heater 4 may be activated at the start of a usage session or only when the user is inhaling. When the user inhales with the article 200, air is drawn through the airflow path 6 and the second heater 4. The air passing through the second heater 4 is heated, and this heated air then enters the chamber 2 and passes through the aerosol-forming substrate 201. The aerosol-forming substrate is already maintained at the standby target temperature. The heat from the incoming airflow provides a boost to the temperature of the aerosol-forming substrate, and the substrate 201 is heated almost instantaneously to a temperature higher than the standby temperature. Therefore, the second heater 4 may be referred to as the boost heater. The temperature may be controlled to a second temperature higher than the standby target temperature 310. This second temperature may be referred to as the operating target temperature 320. The operating target temperature is a temperature above the aerosolization temperature of the aerosol-forming substrate. For example, the target operating temperature may be 250°C, at which temperature the aerosol-forming material and nicotine may volatilize, and an aerosol containing these components may be formed.

[0140] Therefore, the temperature of the aerosol-forming substrate is maintained at a temperature just below the aerosolization temperature using a maintenance heater, and then boosted to a temperature higher than the aerosolization temperature when the user inhales smoke. This offers the advantage that the aerosol-forming substrate depletes its aerosol-forming components only when the user inhales smoke, which can potentially reduce the amount of aerosol-forming material used in the article. If the boost heater is activated only when the user inhales smoke, the dual heating mode configuration can provide energy savings over the duration of the usage session.

[0141] In the embodiments described with reference to Figures 1-3, the maintenance heater is a resistance heater surrounding the chamber 2, and the boost heater is a large-surface-area heater positioned in the airflow path upstream of the cavity. However, it is possible to provide dual-heating mode aerosol generators with other heater configurations. For example, the boost heater may be a heater positioned to directly heat the chamber. For example, the boost heater may be an induction heater positioned to heat a susceptor that is in thermal contact with the aerosol-forming substrate. In a further embodiment, the maintenance heater may surround the chamber, while the boost heater may be an internal heater designed to penetrate the aerosol-forming substrate. Either or both of the heaters may be induction heaters. In another modification, the maintenance heater may be a capacitive or dielectric heater that heats the substrate material with microwaves. Either or both of the heaters may be of the capacitive or dielectric type.

[0142] Figure 4 shows a portion of the aerosol generator 1 described above, further comprising a pressure sensor 7 located upstream of the second heater 4 in the airflow path 6. An exemplary and non-limiting embodiment of the pressure sensor may be a compact piezoresistive absolute pressure sensor, STMicroelectronics LPS22HB, coupled to the control unit of the device 1. The channel 80 extending from the air intake 87 and defining the airflow path 6 has a larger cross-sectional area at the sensing portion 9 where the pressure sensor 7 is located than at the limiting portion 8 upstream of the sensing portion 9. The limiting portion 8 of the channel 80 defining the airflow path 6 acts as a limiter of the airflow path, causing a pressure drop at the sensing portion when the user draws air through the airflow channel 80. Thus, the limiting portion 8 may be referred to as a flow limiter. This pressure drop can be detected by the pressure sensor, from which a signal is transmitted to the control unit, thereby enabling the detection of the start and end of the user's smoke inhalation. The pressure drop resulting from the user's smoke inhalation increases within the region of the limit due to the increase in the air velocity through the limit. This increased pressure drop is easily distinguishable from background pressure changes; that is, the increased pressure drop resulting from the limit helps to amplify the pressure signal resulting from user smoke inhalation above the background noise, which helps to enable detection of user smoke inhalation using a single sensor. In this way, placing the pressure sensor immediately downstream of the limit thus increases the sensitivity of detecting user smoke inhalation.

[0143] The aerosol generating article 200 is inserted into the chamber 2 when in use, and the device is activated. This initiates the use session. The first heater 3 is rapidly heated to its standby operating target temperature, for example, 170°C as described above. The user then inhales or breathes through the mouthpiece 204 of the article 200. This causes the airflow to pass through the device air intake 87, through the flow limiting section 8, through the second heater 4, then through the article 200, and then into the user's mouth.

[0144] The flow limiter 8 reduces the cross-sectional area of ​​the airflow path of the device. Therefore, as air flows through the flow limiter 8, the airflow accelerates and the pressure decreases. The pressure drop generated by the flow limiter 8 is sensed by the pressure sensor 7 of the smoke extraction detection mechanism and relayed to the device's control unit continuously or at frequent intervals, such as every 50 milliseconds. If the pressure inside the flow limiter drops significantly, smoke extraction is detected.

[0145] In response to the detection of smoke extraction, the control device supplies power to the second heater 4. The air passing through the heater is heated to a temperature of approximately 250°C to 300°C. This heated air then passes through the aerosol-forming substrate 201 of article 200, boosting the temperature of the aerosol-forming substrate from the standby target temperature of 170°C to the operating target temperature of 250°C. This heats the aerosol-forming substrate 201 above its aerosolization temperature in order to form an aerosol.

[0146] Note that the second heater may be activated from the start of the usage session, in which case the control unit may supply greater power to the second heater upon detection of user smoke inhalation.

[0147] When the pressure sensor 7 no longer detects a pressure drop in the airflow path, this may indicate that smoke extraction has ended. Therefore, the control unit adjusts the power supplied to the second heater 4 to the value before user smoke extraction. Since the aerosol-forming substrate is no longer receiving a thermal boost through the heated airflow, the temperature of the aerosol-forming substrate drops again to the standby target temperature.

[0148] This process is repeated for each of the multiple inhalations during a usage session, for example, after a predetermined number of inhalations have been performed, or after a predetermined duration from the start of the usage session, until the usage session ends.

[0149] Figure 5 shows a portion of the aerosol generator 501 with an alternative airflow path configuration. The device 501 is shown engaged with the aerosol generating article 200. The device 501 is substantially identical to the devices shown in Figures 1-4, and common components are given the same reference numerals in Figure 5.

[0150] The air inlet 587 of the device 501 is defined by an opening to a channel 580 that defines an airflow path 506 upstream of the second heater 4. The air intake 587 is located adjacent to the opening 12 of the chamber 2. The channel 580 extends along the length of the chamber and passes through thermal contact with the first heater 3 before opening into the second heater 4 located upstream of the chamber 2. The air drawn into the airflow path 506 through the inlet 587 passes through the orifice plate 518, then through the pressure sensor 507, and then enters the second heater 4 and subsequently the chamber 2. The orifice plate 518 forms a restriction in the airflow path 506, creating a pressure drop detectable at the location of the sensor 507 when a user inhales smoke.

[0151] When in use, the apparatus 501 operates in the same manner as the apparatus described above with respect to the apparatus in Figure 4. The air entering through the channel 580 is heated to some extent by the first heater 3, and therefore some of the thermal energy that would otherwise be lost to the system is recovered into the air flowing through the apparatus and passes to the aerosol-forming substrate 201 of the article 200 located in the chamber 2.

[0152] Different aerosol-generating articles may provide different draw-to-discharge (RTDs). This can cause the overall RTD of the system (i.e., the RTD of the aerosol generator and aerosol-generating article combination) to vary. To optimize smoke extraction detection for a particular system, it may be desirable to adjust the pressure drop caused by the limit. Therefore, it may be desirable to provide a test apparatus in which the optimal dimensions of the limit can be determined and the pressure sensor can be calibrated for a particular system.

[0153] Figure 6 shows a portion of the test aerosol generator 601 engaged with an aerosol generating article 200. The device 601 is substantially identical to the device shown in Figure 4, and common components are given the same reference numerals in Figure 6. Thus, the device 601 comprises a chamber 2 for receiving the article 200. The chamber is heated by a first heater 3. A second heater 4 and a pressure sensor 7 are located in the airflow path 6 upstream of the chamber 2. A variable flow limiter 618 is located upstream of the pressure sensor 7, and a flow meter 630 is located upstream of the variable flow limiter 618. The variable flow limiter has threads that can be adjusted to change the cross-sectional area of ​​the airflow path at the limit. It should be noted that many other forms of variable flow limiters, e.g., ball valves, gate valves, or butterfly valves, may be used. The flow meter is configured to measure the actual flow rate and volume through the airflow path as air is drawn through the system. By knowing the actual flow through the system, the signal from the pressure sensor can be calibrated by the flow meter. By using variable limits, the effect on the sensitivity of pressure sensors at different pressure drops can be evaluated. Once appropriate limit dimensions are selected, aerosol generators can be manufactured without the need for flow meters, using fixed limits.

[0154] In some specific embodiments, a first heater (maintenance heater) and a second heater (boost heater) may be combined within a single heater assembly. Figure 7 shows a schematic diagram of a heater assembly that may be used in an aerosol generator according to one embodiment of the present invention. The heater assembly 712 comprises a hollow body portion 714 that partially defines a chamber 716 for receiving a portion of an aerosol generating article. The chamber 716 comprises an open end 718 through which an aerosol generating article can be inserted into the chamber 716, and a closed end 720 opposite the open end 718. More specifically, the hollow body portion 714 comprises a tubular element 728 that partially defines a cylindrical wall 722 of the chamber 716 extending between the open end 718 and the closed end 720. The tubular element 728 is positioned such that when an aerosol generating article is inserted into the chamber 716, the aerosol generating article is received within the tubular element 728 and in direct contact with the tubular element 728. Advantageously, direct contact between the tubular element 728 and the aerosol-generating article facilitates heat transfer from the tubular element 728 to the aerosol-generating article. The tubular element is formed from a thermally conductive material, such as a metallic material like stainless steel.

[0155] The heater assembly further comprises a body portion 730 that is permeable or permeable to airflow. In certain embodiments, the body portion is a porous portion 730 that defines an airflow path 732 through the porous portion 730. The airflow path 732 is upstream of the chamber 716 and is in fluid communication with it. The porous portion 730 comprises a porous plug 734 provided within a tubular element 728.

[0156] The first resistance heater 740 is positioned in contact with the outer surface 727 of the hollow portion 714 of the heater assembly. The first resistance heater is electrically connected to power terminals 741 and 742 to supply power to the heater 740. The first resistance heater 740 is positioned to provide sustained heating to the aerosol-forming substrate positioned in the chamber 716 by maintaining the substrate temperature at a standby target temperature lower than the substrate's aerosolization temperature.

[0157] The second resistance heater 750 is positioned in contact with the outer surface 727 of the porous portion 730 of the heater assembly. The second resistance heater is electrically connected to power terminals 751 and 752 to supply power to the heater 750. The second resistance heater is positioned to heat the porous plug 734 and any air flowing through it. The air thus heated provides a thermal boost to the aerosol-forming substrate positioned within the chamber 716 when the user inhales smoke, thereby raising the substrate's temperature to an operating temperature above its aerosolization temperature while the user inhales smoke. Note that the same power supply may be used to power both the first and second resistance heaters. Alternatively, each heater may have a separate power supply.

[0158] Figure 8 shows a portion of the aerosol generator 800, which includes the heater assembly 712 of Figure 7. The heater assembly 712 is located within the housing 810. A channel 805 defines an airflow path 806 from an air intake 887 defined within the housing of the device, through a porous plug 734 of the heater assembly 712, to the chamber 716. An orifice plate 818 is positioned in the airflow path downstream of the inlet, providing a restriction, and a pressure sensor 807 is located in the airflow path downstream of the restriction 818.

[0159] The apparatus 800 in Figure 8 functions in the same manner as described above in relation to the apparatus in Figure 4 when in use. That is, when the aerosol generator is inserted into the chamber 716 and the apparatus is activated, a usage session is started. The first heater 740 heats the aerosol-forming substrate 201 to a standby operating target temperature, for example, 170°C. The user then inhales or breathes through the mouthpiece 204 of the article 200. This causes the airflow to pass through the apparatus air intake 887, through the orifice plate 818, through the porous plug 734, then through the article 200, and then into the user's mouth. The second heater 750 supplies heat to heat the porous plug 734. Power is supplied to the second heater 750 when the control device receives a signal from the pressure sensor 807 indicating that the user is inhaling smoke. The heated air passing through the porous plug 734 raises the temperature of the aerosol-forming substrate to an operating temperature at which aerosols can be generated.

[0160] The heater assembly 712 described in relation to Figure 7 utilizes a resistance heater positioned on the surface of a conductive material. In some specific embodiments, the heater assembly may be manufactured by molding a conductive resistance-heatable polymer. Electrodes may then be directly attached to parts of the heater assembly to heat those parts of the heater assembly. One example is shown in Figure 9.

[0161] Figure 9 is a schematic diagram of a heater assembly 912 formed from a conductive and resistance-heatable polymer 901. Polymer 901 is a polymeric composite material comprising a polymer matrix and conductive filler particles. In certain embodiments, polymer 901 comprises a polymeric material and at least one particulate filler selected from the list consisting of graphite, graphite-derived materials, and hexagonal boron nitride, wherein the filler is dispersed within the polymeric material. In certain embodiments, the polymeric material forming the matrix is ​​polyether ether ketone (PEEK), but may instead be liquid crystal polymer (LCP). Polymer 901 contains 27 weight percent of the polymeric material, but this amount may be any value between 22 and 33 percent. Polymer 901 contains 65 weight percent of the filler, but this may be any value between 62 and 69 percent. Polymer 901 further comprises an additive, carbon black, dispersed within the polymeric material. Polymer 901 contains 7 weight percent of the additive, but this may be any value between 5 and 9 percent.

[0162] A heating element comprising a polymer matrix and at least one conductive filler particle dispersed within the polymer matrix, comprising graphite, graphite-derived material, and hexagonal boron nitride, is generally easier to manufacture compared to similar heating elements configured for resistance heating. In particular, the thermoplastic properties of the polymer matrix can make the polymer composite suitably malleable, so that the polymer composite is suitable for precise and controlled molding. Therefore, the polymer 901 described is easier to form into an elongated hollow shape compared to other conductive materials typically used in heater assemblies of existing aerosol generators. By controlling and adjusting the concentration and distribution of conductive filler particles dispersed within the polymer matrix, it is advantageous to provide a polymer heating element that can generate sufficient heat by resistance heating to efficiently heat a solid aerosol generating substrate of an aerosol generating article thermally bonded to the heating element. For example, by adjusting the formulation of the polymer matrix and the degree of dispersion of conductive filler particles within the polymer matrix, it is possible to control the resulting conductivity of the polymer and, consequently, the amount of heat resistively generated by the heater assembly when a voltage is applied to the heating element.

[0163] To form the heater assembly 912 shown in Figure 9, a resistance-heatable polymer 901 is heated and extruded to form a hollow tube. This tube forms the outer portion 920 of the heater assembly 912. The granulated polymer is then placed at one end of the tube and lightly sintered to form a porous plug 934 extending across the other end of the tube. The granulated polymer particles sintered to form the porous plug preferably have a number-average particle diameter of less than 800 micrometers, for example, 50 to 600 micrometers. The cross-sectional porosity of the porous plug is preferably greater than 15 percent and less than 45 percent. The total porosity of the porous plug is preferably 0.5 to 5 cubic centimeters, for example, 2 to 3.5 cubic centimeters. The porous plug preferably provides a draw resistance of 10 mmH2O to 40 mmH2O, for example, about 15 mmH2O or about 20 mmH2O.

[0164] The resulting heater assembly 912 has an opening 918 at one end and connects to a chamber 916 defined by an inner wall 922.

[0165] The first electrode pairs 941 and 942 attached to the heater assembly within the cavity 916 allow current to pass through a portion of the heater assembly wall. Because polymer 901 is resistively heatable, the current passing through a portion of the heater assembly heats the heater assembly wall, supplying heat to the aerosol generating substrate located within the cavity. Therefore, the wall of cavity 930 can act as a first heater to provide sustained heating to the substrate located within the cavity.

[0166] The second pair of electrodes 951, 952 attached to the heater assembly within the area of ​​the porous plug 934 allow current to pass through that portion of the heater assembly wall. These electrodes allow the heater assembly wall and the porous plug to be resistively heated. Thus, the porous plug 934 can act as a second heater to heat the air passing through the porous plug and provide a thermal boost to the aerosol-forming substrate when the user inhales smoke.

[0167] The heater assembly described in relation to Figure 9 can be used as a heater assembly in the apparatus 800 described in relation to Figure 8.

[0168] Figure 10 shows a further specific embodiment of a heater assembly 1012 that may be used in embodiments of the present invention. The heater assembly 1012 comprises a hollow body portion 1014 that partially defines a chamber 1016 for receiving a portion of an aerosol generating article 200. The chamber 1016 comprises an open end 1018 through which the aerosol generating article 200 can be inserted into the chamber 1016, and a closed end 1020 opposite the open end 1018.

[0169] More specifically, the hollow body portion 1014 includes a tubular element 1028 that partially defines the cylindrical wall 1022 of the chamber 1016 extending between the open end 1018 and the closed end 1020. The tubular element 1028 is positioned such that when the aerosol-generating article is inserted into the chamber 1016, the aerosol-generating article is received within the tubular element 1028 and comes into direct contact with the tubular element 1028. The tubular element is formed from a ceramic material, such as alumina.

[0170] The projections 1019 extending from the inner wall 1022 of the cavity 1016 limit the extent to which the aerosol-generating article can be inserted into the chamber 1016. These projections allow for a gap between the distal end of the aerosol-generating article and the porous plug 1034. The gap may be 1 mm to 5 mm, for example, 1.5 mm to 3 mm. The gap helps to insulate the aerosol-generating article from the porous plug 1034 so that when a user inhales smoke, the porous plug only affects the temperature of the article.

[0171] The heater assembly further comprises a porous portion 1030 that defines an airflow path 1032 through the porous portion 1030. The airflow path 1032 is upstream of the chamber 1016 and is in fluid communication with it. The porous portion 1030 comprises a porous plug 1034 provided within a tubular element 1028.

[0172] The first resistance heater 1040 is located within the tubular element 1028 in the hollow portion 1014 of the heater assembly. The first resistance heater is electrically connected to power terminals 1041 and 1042 to supply power to the heater 1040. The first resistance heater 1040 is positioned to provide sustained heating to the aerosol-forming substrate located within the chamber 1016 by maintaining the substrate temperature at a standby target temperature lower than the substrate's aerosolization temperature.

[0173] A second resistance heater 1050 is located within the tubular element 1028 in the porous portion 1030 of the heater assembly. The second resistance heater is electrically connected to power terminals 1051 and 1052 to supply power to the heater 1050. The second resistance heater is positioned to heat the porous plug 1034 and any air flowing through it. The air thus heated provides a thermal boost to the aerosol-forming substrate positioned within the chamber 1016 when the user inhales smoke, thereby raising the substrate's temperature to an operating temperature above its aerosolization temperature while the user inhales smoke.

[0174] Figures 11 and 12 are schematic diagrams of further specific embodiments of a heater assembly 1112 that may be used in embodiments of the present invention. The heater assembly 1112 is formed from a conductive and resistance-heatable polymer 901 formed from a polymer composite material comprising a polymer matrix and conductive filler particles. The heater assembly 1112 is substantially identical to the heater assembly 912 described in connection with Figure 9, and similar features are given the same reference numerals as the assembly in Figure 9. The projection 1119 may be located within the chamber 916 and provides a gap between an aerosol-forming substrate inserted into the chamber and a porous plug 934 defining the end of the chamber.

[0175] The resistance-heatable polymer 901 of the heater assembly 1112 is heated by an electric current passing between a first annular contact 1141 located at the first end 1121 of the tubular outer portion 920 of the heating assembly and a second annular contact 1142 located at the second end 1122 of the tubular outer portion 920. The contacts 1141, 1142 may be copper rings attached to the heating body, for example, by mechanical interaction or by an external coating process. Conductive adhesives may also be used to attach the contacts, for example, HT-carbon adhesive or silver epoxy adhesive. The arrangement of the porous plug 934 across the second annular contact 1142, the tubular outer portion 920 of the heating assembly 112, and the second end 1122 of the heater assembly 1112 is shown in the end section view of the heater assembly 1112 shown in Figure 12.

[0176] During use, a voltage is applied between the first annular contact 1141 and the second annular contact 1142, causing a current to flow, which resistively heats the outer portion 920 of the heater assembly 1112. The heat from the heater assembly within the cavity region can heat the aerosol-forming substrate inserted into the cavity. The heat from the heater assembly within the region of the porous plug 934 can heat the porous plug. When a user inhales smoke, the incoming air is heated as it passes through the porous plug 934, providing a thermal boost to the aerosol-forming substrate within the cavity.

[0177] Figures 13 and 14 show alternative electrical connections for the heater assembly 1312 formed from the resistance-heatable polymer described above. The heater assembly 1312 may comprise a first annular contact 1341 located at the first end 1321 of the heater assembly and a second contact 1342 embedded in the porous plug 934 portion of the heating assembly 1312. The second contact 1342 may comprise multiple branches 1343 to extend the electrical connection over a wider area of ​​the porous plug 934. The operation of the heating assembly is substantially as described above in relation to Figures 11 and 12.

[0178] Figures 15 and 16 show alternative electrical connections for the heater assembly 1412 formed from the resistively heatable polymer described above. Instead of contacts located at opposing ends 1421 and 1422 of the heater assembly 1412, the assembly has first contacts 1441 and second contacts 1442, both located on radially opposite portions of the second end 1422 of the assembly. The current passing between the first contact 1441 and the second contact 1442 acts to resistively heat the heater assembly 1412 at the second end 1422, thereby heating the porous plug 934. The heat generated at the second end 1422 of the heater assembly is transferred by conduction toward the first end 1421 of the heater assembly 1412. Thus, the heat transferred toward the first end 1421 of the heater assembly can be used to provide sustaining heat to the aerosol-forming substrate located within the cavity 916. The electrical configuration shown in Figures 15 and 16 may allow the porous plug to be heated to a higher temperature than the portion of the heater assembly that defines the chamber 916.

[0179] Figure 18 shows a schematic diagram of a heater assembly that may be used in an aerosol generator according to one embodiment of the present invention. The heater assembly 1812 defines a first body portion 1814 having a chamber 1816 for receiving a portion of an aerosol generating article. The chamber 1816 has an open end 1818 through which the aerosol generating article can be inserted into the chamber 1816. The heater assembly 1812 defines a thin cylindrical wall 1822. The thin cylindrical wall is formed from a thermally conductive material, such as a ceramic material such as zirconia or alumina.

[0180] The heater assembly further comprises a second body portion 1830. The second body portion 1830 is located upstream of the chamber 1816 and defines an airflow path 1832 that is in fluid communication with it. In this particular embodiment, the second body portion 1830 comprises a resistance heating coil 1834.

[0181] The projections 1819 extending from the inner wall of the cavity 1816 limit the extent to which the aerosol-generating article can be inserted into the chamber 1816. These projections allow for a gap between the distal end of the aerosol-generating article and the resistance heating coil 1834.

[0182] The first resistance heater 1840 is positioned in contact with the outer surface 1827 of the first body portion 1814. The first resistance heater 1840 is positioned to provide sustained heating to the aerosol-forming substrate positioned within the chamber 1816 by maintaining the substrate's temperature at a standby target temperature lower than its aerosolization temperature.

[0183] The resistance heating coil 1834 is positioned within the second body section 1830 to heat any airflow passing through the second body section 1830. This heated air provides a thermal boost to the aerosol-forming substrate positioned within the chamber 1816 when the user inhales smoke, thereby raising the substrate's temperature to an operating temperature above its aerosolization temperature while the user inhales smoke. A pair of electrodes 1841, 1842 attached to the resistance heating coil 1834 allow current to pass through it. Note that the same power supply may be used to power both the first resistance heater 1840 and the resistance heating coil 1834. Alternatively, each heater may have a separate power supply.

[0184] For the purposes of this specification and the appended claims, unless otherwise indicated, all numerical values ​​representing quantities, amounts, percentages, etc., should be understood in all cases as being modified by the term “approximately.” Furthermore, all ranges include the disclosed maximum and minimum points and any intermediate ranges therewith, which may or may not be specifically listed herein. Thus, in this context, number A is understood as A ± 10 percent (10%) of A. In this context, number A may be considered to include numerical values ​​that fall within the general standard error to the measured value of the characteristic modified by number A. In some cases used in the appended claims, number A may deviate by the percentages listed above, provided that the amount of deviation of A does not substantially affect the basic and novel characteristics of the claimed invention. Furthermore, all ranges include the disclosed maximum and minimum points and any intermediate ranges therewith, which may or may not be specifically listed herein.

Claims

1. An aerosol generator configured to generate aerosols from an aerosol-forming substrate, The apparatus defines a cavity for receiving at least a portion of the aerosol-forming substrate, and an airflow path upstream of the cavity through which a user can draw air when using the apparatus, wherein the airflow path fluidly connects the cavity to the external environment. The aforementioned device is The first heating portion located in the aforementioned cavity, It comprises a second heating portion located in thermal contact with the airflow path upstream of the cavity, The apparatus is configured to heat the aerosol-forming substrate during the usage session with reference to two different target temperatures, a standby target temperature and an operating target temperature, wherein the standby target temperature is higher than room temperature and the operating target temperature is higher than the standby target temperature, and the apparatus is configured to heat the aerosol-forming substrate to the standby temperature during the usage session, and the apparatus is further configured to heat the aerosol-forming substrate from the standby target temperature to the operating target temperature during user smoke extraction performed during the usage session, and the aerosol-forming substrate is made coolable from the operating target temperature after the user smoke extraction is completed. An aerosol generator wherein the first heating portion is configured to supply energy to heat the aerosol-forming substrate to the standby temperature, and the second heating portion is configured to heat the aerosol-forming substrate to the operating temperature during user smoke extraction.

2. The aerosol generating apparatus according to claim 1, wherein the first heating portion comprises a heater disposed in contact with the wall of the cavity, for example, a resistance heater disposed in contact with the wall of the cavity.

3. The aerosol generating apparatus according to claim 2, wherein the first heating portion comprises a flexible heater disposed in contact with the inner or outer surface of the cavity, for example, a polyimide flexible heater disposed in contact with the inner or outer wall of the cavity.

4. The aerosol generator according to any one of claims 1 to 3, wherein the second heating portion comprises an induction heating device, for example, the second heating portion comprises an inductor configured to heat a susceptor located in the airflow path upstream of the cavity.

5. The aerosol generator according to any one of claims 1 to 4, wherein the second heating portion includes a porous body, and the airflow path is defined through the porous body.

6. The aerosol generator according to any one of claims 1 to 5, wherein the second heating portion comprises a heating element configured for Joule heating, and the heating element comprises a polymer composite material comprising a polymer matrix and a plurality of conductive particles dispersed within the polymer matrix.

7. The aerosol generator according to any one of claims 1 to 6, wherein the first heating portion is formed by a cylindrical or tubular element made of a resistance material, and the second heating portion is formed as a porous body inside the end of the cylindrical or tubular element opposite to the open end for receiving the aerosol forming substrate, and the cavities of the porous body form the airflow path.

8. The aerosol generator according to any one of claims 1 to 7, wherein the first heating portion is formed by a cylindrical or tubular element made of a resistance material, and the second heating portion is formed as a permeable body having a plurality of tubular or meandering structures inside a portion of the cylindrical or tubular element opposite to the open end for receiving the aerosol forming substrate, for example, the end portion, and the tubular or meandering structures of the permeable body form the airflow path.

9. The aerosol generator according to any one of claims 1 to 8, wherein the first heating portion and the second heating portion are formed as a single structure of a heater material having the same electrical resistance.

10. The aerosol generating article according to any one of claims 6 to 9, wherein the polymer composite material comprises a polymer matrix and a plurality of nonmetallic conductive particles dispersed within the polymer matrix, such as a plurality of carbon particles such as graphite particles, or hexagonal boron nitride particles such as boron nitride particles.

11. The aerosol generator according to claim 7 or claim 8, wherein the polymer matrix comprises at least one of polyether ether ketone (PEEK) and liquid crystal polymer (LCP).

12. The aerosol generator according to any one of claims 1 to 11, configured to generate an aerosol from an aerosol-forming substrate during a usage session, wherein both the first heating portion and the second heating portion are activated at the start of the usage session, the first heating portion is configured to directly heat the aerosol-forming substrate received in the cavity, and the second heating portion is configured to heat the air drawn into the airflow path by user smoke extraction.

13. For example, the aerosol generator according to any one of claims 1 to 12, wherein power is supplied only to the second heating portion during the user's inhalation, or power supplied to the second heating portion is increased during the user's inhalation, and is configured to detect the user's inhalation.

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