Aerosol generator with airflow detection function

Abstract

An aerosol generator (1, 501, 601) for generating an aerosol from an aerosol-forming substrate (201) defines a cavity (2) for receiving at least a portion of the aerosol-forming substrate and an upstream airflow path (6, 506) through which a user can inhale air when using the device. The airflow path connects the cavity to the external environment. A pressure sensor (7, 507) is located in communication with the upstream airflow path of the cavity, and the device is configured to use signals from the pressure sensor to detect one or more user inhalations performed during use of the device. Restriction of the airflow path can enhance the pressure drop associated with user inhalations, thereby amplifying the sensitivity of the pressure sensor.

Description

[Technical Field]

[0001] This disclosure relates to an aerosol generator. This disclosure also relates to an aerosol generating system equipped with an aerosol generator, and to 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 containing an aerosol-forming substrate. During use, the aerosol generating device heats the aerosol-forming substrate of the aerosol generating article to form an aerosol.

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

[0004] For example, electrically operated aerosol generators, such as handheld aerosol generators, can be used in conjunction with such aerosol-generating articles. Such electrically operated aerosol generators may include a heating element configured to heat the aerosol-forming substrate to a temperature of several hundred degrees Celsius. This causes volatile compounds entrained in the air drawn in 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 examples of aerosol generators for consuming aerosol-generating articles are disclosed in the Art. Such a device is, for example, an electrically heated aerosol generator in which an aerosol is generated by heat transfer from one or more electric heater elements of the aerosol generator to an aerosol-generating element of the aerosol-generating article. For this purpose, the aerosol-generating article can 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, an electrically heated aerosol generator has been proposed that includes an internal heater blade adapted to be inserted into the aerosol generating substrate when an aerosol generating article is received into the heating cavity. Alternatively, heating of the aerosol generating substrate is achieved using external heating, such as by a tubular heater element that at least partially defines the heating cavity into which the aerosol generating article is inserted, or is otherwise connected to a tubular element defining the heating cavity.

[0007] Induction-heated aerosol generating articles have also been 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 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 is 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 maintenance temperature during a use session. The device may be configured to raise the temperature of the aerosol-forming substrate from the standby temperature to, for example, the operating temperature when a user inhales smoke. For example, the device may be configured to provide a thermal boost to the aerosol-forming substrate during user smoke inhalation performed during a user session. Such configurations may allow the aerosol-forming substrate to be heated to a first temperature, for example, the standby temperature which is required to form an aerosol, or slightly below, and then to a higher temperature which is required to form an aerosol during user smoke inhalation, for example, the operating temperature.

[0011] By selecting an appropriate standby temperature, the aerosol-forming substrate can boost its temperature to the operating temperature almost instantaneously by applying further thermal energy to the substrate. After user fumes are absorbed, the temperature can be reduced back down to the standby temperature.

[0012] The combination of heating to standby temperature and rapid temperature rise to operating temperature during inhalation 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. This may reduce the formation of undesirable aerosol components and potentially lead to optimal harvesting of desirable components.

[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 the user can inhale air when using the device. The airflow path may connect the cavity to the external environment. The device may include flow detection means, such as a pressure sensor, located in communication with the airflow path upstream of the cavity. The device may be configured to use signals from the flow detection means, such as a pressure sensor, to detect one or more user inhalations performed during a usage session.

[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 airflow path upstream of the cavity from which a user can inhale air when using the device, the airflow path connecting the cavity to the external environment. The device further comprises a flow detector or flow detection means, including, for example, a pressure sensor located in communication with the airflow path upstream of the cavity. The device is configured to use signals from the flow detector or flow detection means, for example, the pressure sensor, to detect one or more user smoke inhalations performed during a usage session.

[0015] A cavity may also be called a chamber, and it should be noted that in this specification, the terms cavity and chamber are used interchangeably to mean part of a device for receiving at least a portion of an aerosol-forming substrate so that the substrate can be heated to generate an aerosol.

[0016] The airflow path upstream of the cavity preferably acts as a flow limiter or is equipped with a flow limiter. For example, a flow limiter may comprise a mechanical element such as an orifice plate located within the airflow path. As a further example, 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, causing a pressure drop. Flow limiting can enhance the pressure drop created when a user inhales air through the airflow path. Thus, flow limiting can increase the sensitivity of smoke inhalation detection. For example, the increased pressure drop associated with flow limiting within a portion of the airflow path may improve the ability of a pressure sensor to accurately detect user smoke inhalation.

[0017] The flow limiter may 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 and form different types of aerosol-generating articles. The limiter may be varied to optimize smoke detection for a particular user.

[0018] A portion of the airflow path upstream of the cavity is 3 mm 2 Less than, for example, 2 mm 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. 2 Less than, for example, 0.4 mm 2 Less than 0.2 mm 2 Less than 0.1 mm 2It may have a cross-sectional area less than . Such a cross-sectional area may provide flow limiting, for example, to amplify the sensitivity of the pressure sensor to changes in airflow associated with user smoke extraction.

[0019] 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 have greater draw resistance than an airflow path with a single inlet of the same cross-sectional area as the combined inlets, and therefore may cause a greater pressure drop downstream of the inlets.

[0020] The airflow path upstream of the cavity may preferably have a draw-out 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 draw-out resistance (RTD) between 10 mmH2O and 50 mmH2O.

[0021] When used herein, the draw resistance 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.

[0022] The flow restrictor may be any suitable flow restriction that causes a pressure drop in the airflow path measurable by the pressure sensor when the user smokes the aerosol generating device.

[0023] In some preferred embodiments, the flow restrictor is provided by the inlet of the airflow path. The inlet may comprise a plurality of 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. One or more inlets may have any suitable size and shape to provide a desired draw resistance and pressure drop within the airflow path when the user smokes the aerosol generating device. 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. One or more inlets are preferably arranged to allow ambient air to be drawn into the aerosol generating device. One or more inlets may have a total cross-sectional area smaller than the cross-sectional area of the airflow path immediately downstream of the one or more inlets.

[0024] The pressure sensor is located at the flow restrictor and can detect the pressure drop associated with the increase in the velocity of the air passing through the flow restriction during user smoking. The pressure sensor may be located upstream of the cavity but downstream of the flow restrictor. The flow restrictor may enhance the pressure drop associated with user smoking, increase the sensitivity of the pressure sensor, and improve the accuracy of smoking detection.

[0025] The airflow path upstream of the cavity may include a flow limiter, and further downstream of the flow limiter, an expansion zone may be provided. The pressure sensor is preferably located in or within the expansion zone. This configuration can optimally amplify the sensitivity of the pressure sensor. For example, the airflow path may be at least partially defined by a channel having a first portion with a first cross-sectional area and a second portion with 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.

[0026] The airflow path upstream of the cavity may further comprise an inlet section having an inlet cross-sectional area. The inlet cross-sectional area may be larger than the first cross-sectional area. The airflow path may be at least partially defined by an upstream section having an upstream cross-sectional area, a central section having a central cross-sectional area, and a downstream section having a downstream cross-sectional area. The upstream cross-sectional area may be larger than the central cross-sectional area. The downstream cross-sectional area may be larger than the central cross-sectional area. The pressure sensor is preferably located within the downstream section. The central section may form a flow limiter. The downstream section may form an expansion zone.

[0027] For example, the upstream section may be the entrance section, the central section may be the first part, and the downstream section may be the second part as defined above.

[0028] 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 the second cross-sectional area, for example, the third portion forming a second flow limiter.

[0029] The airflow path upstream of the cavity may include a first flow limiter and a second flow limiter, and the pressure sensor is 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 be advantageous in preventing blowback of steam from the steam chamber that could contaminate the pressure sensor.

[0030] 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 redundancy in the system.

[0031] 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.

[0032] 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, which can function as a reference signal or baseline signal, to help improve the accuracy of smoke inhalation detection. 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 user smoke inhalation.

[0033] 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 thermal energy that would otherwise be lost. By enabling heating of the airflow path in this manner, less energy may be required to achieve the desired temperature in the aerosol-forming substrate.

[0034] The device preferably includes 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 the relative pressure at a location in the airflow path compared 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. The pressure sensor is preferably 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.

[0035] 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 inhalation periods and non-smoke inhalation periods. A smoke inhalation period may be defined as any period during a usage session in which the user is actively inhaling smoke. A non-smoke inhalation period may be defined as any period during a usage session in which the user is not actively inhaling smoke.

[0036] 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.

[0037] Therefore, the device is preferably configured to control the temperature of the aerosol-forming substrate with reference to the standby target temperature during non-fumigation periods and the operating target temperature during fumigation periods. As a result, during non-fumigation periods, the substrate temperature is consistently maintained at the standby target temperature. When the start of user fumigation is detected, the temperature rises to the operating target temperature, and after user fumigation ends, the temperature drops again to the standby target temperature.

[0038] Accordingly, according to an aspect of the present invention, an aerosol generator is provided which is configured to generate an aerosol from an aerosol-forming substrate during a usage session, for example, the above-described aerosol generator 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, the device is configured to heat the aerosol-forming substrate to the standby temperature during a usage session, the device is further configured to heat the aerosol-forming substrate from the standby target temperature to the operating target temperature during user smoke inhalation performed during a usage session, and the aerosol-forming substrate is provided which is configured to cool from the operating target temperature after the user smoke inhalation is completed.

[0039] Accordingly, according to aspects of the present invention, an aerosol generator is provided which is configured to generate an aerosol from an aerosol-forming substrate during a usage session, for example, the above-described aerosol generator 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, the smoke absorption period is defined as any period during a usage session in which the user is actively inhaling smoke, the non-smoke absorption period is defined as any period during a usage session in which the user is not actively inhaling smoke, the device is configured to operate in standby mode during the non-smoke absorption period, and when operating in standby mode, the temperature of the aerosol-forming substrate is controlled with reference to the standby target temperature, and the device is configured to operate in operating mode during the smoke absorption period, and when operating in operating mode, the temperature of the aerosol-forming substrate is controlled with reference to the operating target temperature.

[0040] Accordingly, according to an aspect of the present invention, an aerosol generator is provided which is configured to generate an aerosol from an aerosol-forming substrate during a usage session, for example, the above-described aerosol generator is configured which is configured which heats the aerosol-forming substrate during a usage session according to a standby mode or an operating mode, wherein in standby mode the temperature of the aerosol-forming substrate is controlled with respect to a standby target temperature, and in operating mode the temperature of the aerosol-forming substrate is controlled with respect to 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 operation of 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.

[0041] 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 component of the substrate. 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 used as an aerosol-forming material in the aerosol-forming substrate, or lower than the boiling point of glycerol, or lower than the boiling point of a particular mixture of propylene glycol and glycerol. The standby temperature may alternatively be called the maintenance temperature.

[0042] 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.

[0043] 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 mixture of aerosol-forming materials in the aerosol-forming substrate, for example, higher than the boiling point of propylene glycol used as an aerosol-forming material in the aerosol-forming substrate, or higher than the boiling point of glycerol, or higher than the boiling point of a particular mixture of propylene glycol and glycerol.

[0044] 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.

[0045] 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 change throughout the usage session, taking into account that the user consumes aerosol-forming components when inhaling during the usage session.

[0046] 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 vary from smoke inhalation to smoke inhalation. Variations 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 it consumes aerosol-forming components throughout the usage session.

[0047] 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 during the usage session in which the user is actively performing smoke absorption, and the non-smoke absorption period may be defined as any period during 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.

[0048] 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.

[0049] A usage session may have a usage session duration, for example, a predetermined duration set with reference to time, or with reference to usage parameters, or with reference 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 amount of aerosol generated during the usage session, and the power supplied to the heater during the usage session.

[0050] 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.

[0051] Advantageously, the device may be configured to characterize user inhalation during a usage session, for example, each inhalation performed during the usage session. For example, the device may be configured to determine the amount of aerosol generated during user inhalation during a usage session, for example, each user inhalation performed during the usage session.

[0052] The apparatus preferably includes a power source, such as a battery, which is a rechargeable battery for supplying energy to heat the aerosol-forming substrate.

[0053] The apparatus preferably includes at least one heater for heating the aerosol-forming substrate. For example, the apparatus may include a heater for heating the external portion of the aerosol-forming substrate. Such an external heater may surround or partially surround a portion of the aerosol-forming substrate received within the apparatus. The external heater can be a preferred heater for heating the substrate received within the cavity to a standby target temperature, as the aerosol-forming substrate can be heated to a uniform temperature without contact between the substrate and the heater.

[0054] The apparatus may include 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 within the apparatus.

[0055] The apparatus may include a heater for heating the air in the airflow path upstream of the aerosol-forming substrate, for example, a heater that heats the air drawn into the apparatus and acts so that the heated air heats the aerosol-forming substrate received into the apparatus.

[0056] The device may be configured to activate the heater when it detects user inhalation. For example, the heater may be configured to heat the aerosol-forming substrate after the device detects the start of user inhalation. The heater may be configured to stop after the device detects the end of user inhalation.

[0057] The aerosol generator preferably includes a controller for controlling aerosol generation, such as a controller that communicates with a power supply and heaters. Such a controller can receive signals from, for example, a pressure sensor and determine whether or not fumes are being extracted. Based on these incoming signals, the controller can control the power supply to one or more heaters.

[0058] The device may be configured to characterize user fumigation by monitoring a parameter representing the power supplied by the power supply. For example, the power supply may provide power to maintain the heater at a predetermined temperature during a usage session. The controller may be configured to monitor a parameter representing the power supplied by the power supply. When a user fumigates the device to generate an aerosol, the heater cools down and requires more power to maintain the heater at a predetermined temperature. Therefore, by monitoring a parameter representing the power supplied by the power supply, the device can characterize user fumigation, which is defined by the start and end of fumigation.

[0059] The apparatus may include one or more resistance heaters arranged to heat an aerosol-forming substrate received within a cavity in the apparatus. For example, any of the above-mentioned heaters may be resistance heaters.

[0060] The apparatus may include an induction heater disposed to heat an aerosol-forming substrate received within a cavity of the apparatus. For example, the apparatus may include an inductor disposed to heat a susceptor disposed in thermal communication with the aerosol-forming substrate received within a cavity of the apparatus. Any of the above-mentioned heaters may be induction heaters. The susceptor, which may also be called a susceptor element, may include or consist of one or more susceptor materials.

[0061] Suitable susceptor materials may 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 may include ferromagnetic materials, such as ferrite iron, ferromagnetic steel or stainless steel alloys, ferromagnetic particles, and ferrite. The susceptor material may contain more than 5 percent of ferromagnetic or paramagnetic material, preferably more than 20 percent of ferromagnetic or paramagnetic material, and more preferably more than 50 percent or more than 90 percent of ferromagnetic or paramagnetic material. Suitable susceptor materials may include metals, metallic alloys, or carbon.

[0062] The apparatus may include, for example, a capacitive or dielectric heater for heating an aerosol-forming substrate received in a cavity of the apparatus, wherein the apparatus includes opposing electrodes supplied by a high-frequency AC signal via an impedance matching circuit, and the substrate located in the cavity between the two opposing electrodes is heated by microwaves.

[0063] In some embodiments, the aerosol generator may include a heater assembly. Therefore, one or more heaters in the aerosol generator may be part of a heater assembly. The heater assembly may include a heating body configured for resistance heating. The heating body may include a polymer composite material comprising a polymer matrix and at least one of graphite, graphite-derived material, and hexagonal boron nitride dispersed within the polymer matrix. A heating body comprising a polymer matrix and at least one filler particle of graphite, graphite-derived material, and hexagonal boron nitride dispersed within the polymer matrix may be easier to manufacture than a similar heating body configured for resistance heating made of other conductive materials typically used in existing heater assemblies for aerosol generators. For example, the thermoplastic properties of the polymer matrix may allow the polymer composite material to be conveniently malleable, thereby allowing the polymer composite material to take on a precise and controlled shape. In particular, polymer composite materials may be easier to form into elongated hollow shapes compared to conductive materials typically used in existing heater assemblies for aerosol generators.

[0064] In some cases, it is possible to provide a heating body that can generate sufficient heat by resistance heating to efficiently heat the solid aerosol generating substrate of an aerosol generating article thermally bonded to the heating body, by controlling and adjusting the concentration and distribution of conductive filler particles dispersed within the polymer matrix.

[0065] The heater assembly may comprise a substantially porous heating body. The porous heating body may be configured to convectively transfer heat to the airflow entering the aerosol generator so that the airflow reaches the aerosol generating substrate in a preheated state. This may be beneficial in that aerosol-forming species present in the aerosol generating substrate can be released more efficiently with heating. Generally, it may be possible to supply and exchange heat more efficiently during the use of the aerosol generator.

[0066] To be heated, air is drawn in through a porous heating body. The residence time of air in the porous body, i.e., the average time spent by fluid packets within a controlled volume, is a function of the porosity and curvature of the porous body, as well as its geometric shape. The porosity, average pore size and pore size distribution, and specific surface area of ​​the porous body also affect the amount of heat exchanged convectivally. At the same time, the porosity and meandering of the porous body affect the draw-out resistance (RTD) of the porous body and the heating body as a whole. By adjusting the porosity, length, and diameter of the porous body, a satisfactory balance can be struck between the ability to efficiently preheat the air flowing through the porous body and the RTD of the porous body.

[0067] The apparatus is preferably configured to determine the temperature of the aerosol-forming substrate during use. For example, the apparatus may include a controller configured to determine the temperature of the aerosol-forming substrate during use, the temperature being determined by monitoring the behavior of the heater during use, for example, by monitoring the apparent resistance or apparent conductance of the heater. The apparatus may also include 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 temperature control element.

[0068] 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 a 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 a pressure sensor and optimizing features such as the dimensions of a flow limiter may be any aerosol generator described herein with an additional flow meter 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 and the dimensions of the limiter can be optimized, for example, for a particular aerosol-generating article. A commercially available version of the aerosol generator may then be manufactured with the desired settings, without requiring a flow meter.

[0069] Advantageously, the aerosol generator may be configured such that, upon use, it determines the start of a usage session and enters a standby mode in which the aerosol-forming substrate received within the device is heated, during which the temperature of the aerosol-forming substrate is controlled with reference to a standby target temperature, detects user smoke inhalation during the usage session and, in response to the detected user smoke inhalation, enters an operating mode in which greater thermal energy is supplied to the aerosol-forming substrate to raise its temperature, and during the operating mode, the temperature of the aerosol-forming substrate is controlled with reference to an operating target temperature higher than the standby target temperature.

[0070] 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.

[0071] The device may include one or more power supplies or power sources, one or more heaters, and a controller. The controller may be configured to enter standby mode at the start of a usage session, detect the start of user smoke inhalation and switch from standby mode to operating mode in response to the detection of the start of user smoke inhalation, detect the end of user smoke inhalation and switch from operating mode to standby mode in response to the detection of the end of user smoke inhalation.

[0072] 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 startups of the aerosol generating system.

[0073] The controller or control circuit may be any suitable controller or electrical component, or may include any suitable controller or electrical component. The controller 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, 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 is started, 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 controller may be configured to increase the power supplied to one or more heaters during operation mode compared to standby mode.

[0074] The apparatus may include a first heater and a second heater. The first heater may be configured to heat the aerosol-forming substrate during standby mode, while the second heater may be configured not to heat the aerosol-forming substrate during standby mode.

[0075] Both the first and second heaters may be arranged to simultaneously heat the aerosol-forming substrate during the operating mode.

[0076] The first heater may be configured to operate throughout the entire usage session, while the second heater may be configured to operate only while the user is smoking. For example, the second heater may be switched on only while the user is smoking. Alternatively, the second heater may operate throughout the entire usage session, but the power supplied to the second heater may be increased while the user is smoking.

[0077] 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 is configured to be at least partially received within the aerosol generating device. The aerosol forming article may comprise a plurality of components, including an aerosol forming substrate assembled within a wrapper.

[0078] In some embodiments, the aerosol-generating article may have a draw-out resistance (RTD) of 10 mmH2O to 50 mmH2O.

[0079] The 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 draw-out resistance (RTD) of 20 mmH2O to 100 mmH2O.

[0080] 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.

[0081] 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, in the axial central portion of the aerosol-forming substrate, for example, the axial central cylindrical portion or the axial central right cylinder portion, may be or contain the aerosol-forming material. The outer portion, in the axial outer portion of the aerosol-forming substrate, may be or contain the aerosol-forming material. 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 present in the inner and outer portions.

[0082] 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 (if present), and mouth-side plug filter are surrounded by the wrapper.

[0083] Optionally, the front plug is located at the upstream end of the article. Optionally, the aerosol-forming substrate is located downstream of the front plug. Optionally, the first hollow tube is located downstream of the aerosol-forming substrate. Optionally, the second hollow tube is located downstream of the first hollow tube. Optionally, the 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, directly inhale the mouth end of the article.

[0084] 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, straight cylindrical. 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.

[0085] 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.

[0086] A 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 called a flat or planar cartridge. The cartridge may be any suitable shape and size, for example, substantially cylindrical or cubic. The cartridge may be any of the cartridges described in WO2015177043, the contents of which are incorporated herein.

[0087] 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 called a flat or 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 called a flat or planar aerosol-forming substrate.

[0088] The susceptor may form part of the inner surface of the cartridge housing, be attached to it, or be located adjacent to it. The susceptor may be in contact with the aerosol-forming substrate. The susceptor 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. Advantageously, this may maximize heat transfer from the susceptor to the aerosol-forming substrate during use.

[0089] 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 a user can inhale air when using the device, the airflow path connecting the cavity to the external environment; and a pressure sensor positioned 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; detecting a pressure change in the airflow path associated with the start of user inhalation; detecting a pressure change in the airflow path associated with the end of user inhalation; and thereby detecting user inhalation.

[0090] 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 a user can inhale air when using the device, the airflow path connecting the cavity to an external environment; and a pressure sensor positioned in communication with the airflow path upstream of the cavity, the method comprising: arranging an aerosol-forming substrate in the cavity; operating the device 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.

[0091] 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 a user can inhale air when using the device, the airflow path connecting the cavity to an external environment, wherein the method comprises the steps of: arranging the aerosol-forming substrate in the cavity; operating the device in a standby mode in which the temperature of the aerosol-forming substrate is controlled with reference to a standby target temperature; and switching the mode of operation from the standby mode to an operating mode in response to user inhalation of smoke, wherein the operating target temperature is higher than the standby target temperature.

[0092] The method for generating aerosols may involve any of the above-mentioned devices or systems.

[0093] As used herein, the term “aerosol-generating article,” or simply “article,” may refer to an article that, for example, generates or releases an aerosol when heated.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] As used herein, the term “aerosol-forming compound” may refer to any suitable known compound or mixture of compounds that facilitates aerosol formation in 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.

[0099] 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 the lowest temperature at which the aerosol-forming substrate releases an aerosol or a substantial amount of a volatile compound capable of forming an aerosol.

[0100] As used herein, the term “usage session” may refer to a period of time during which a user applies a series of fumes to extract aerosols from an aerosol-forming substrate.

[0101] As used herein, the term “aerosol generator” may refer to a device used in conjunction with an aerosol generating article to enable the generation or release of an aerosol.

[0102] 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. The heating of the susceptor may be the result of at least one of hysteresis losses and eddy currents induced within the susceptor, depending on the electrical properties and magnetism of the susceptor material.

[0103] When referring to an aerosol generating article or aerosol generating device, the terms “upstream” and “downstream” as used herein may be used to describe the relative positions of components or parts of components of an aerosol generating article or device with respect to the direction in which air flows through the aerosol generating article or device during 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, passes through the upstream end of an aerosol generating article that engages with the device, and exits from the downstream end of the aerosol generating article.

[0104] As used herein in connection with the present invention, the term “longitudinal direction” is used to describe the direction between the upstream and downstream ends of an aerosol generating article, or between the upstream and downstream ends of an aerosol generating device. During use, air is drawn through the aerosol generating article in the longitudinal direction.

[0105] As used herein in connection with the present invention, the term "length" is used to represent the maximum dimension in the longitudinal direction of an aerosol generating article, or an aerosol generating device, or a component of an aerosol generating article or aerosol generating device.

[0106] 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, references to “cross section” of an aerosol generating article or aerosol generating device or components of an aerosol generating article or aerosol generating device refer to a cross-section.

[0107] 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 substantially corresponds to the diameter of the component of the aerosol generating article.

[0108] As used herein, the term "heating body" means a component configured to transfer thermal energy to an aerosol generating substrate.

[0109] As used herein, the term “porous portion” means a portion of a body having multiple pores, at least a portion thereof being interconnected. Thus, the porous portions of a body can generally define airflow paths through the porous portion so that a fluid can 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 having a porous portion of the same length and a free cross-sectional area equal to the total cross-sectional area of ​​the porous portion. Thus, flow across a porous portion is generally partially restricted compared to flow through a hollow tubular element of comparable dimensions.

[0110] The term "porosity" of the main body generally refers to the ratio of the volume of accessible voids and air pockets to the bulk volume occupied by the main body. The term "cross-sectional porosity" refers to the fraction of air pockets in the cross-sectional area of ​​a porous body, for example, the cross-section of the porous portion of the heating body of the heater assembly according to the present invention. Cross-sectional porosity is the area ratio of air pockets 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 comprising the heater assembly.

[0111] The porous body is typically substantially cylindrical, and thus the cross-section 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-section of the porous body lies in a plane that is substantially perpendicular to the longitudinal axis.

[0112] As used herein, the term "electrically insulating" refers to a material having an electrical conductivity of less than 0.8 × 10 4 Siemens / meter at room temperature (20 °C) and 50% relative humidity, for example, in at least one direction, such as all directions, having a resistivity of at least 1 × 10 -4 , 5 × 10 -4 , or 1 × 10 -5 ohm-meter.

[0113] As used herein, the term "electrically resistive" refers to a material having an electrical conductivity of at least 0.8 × 10 6 Siemens / meter at room temperature (20 °C) and 50% relative humidity, for example, in at least one direction, such as all directions, having a resistivity of 1 × 10 -4 , 5 × 10 -5 , or 1 × 10 -5 ohm-meter or less.

[0114] 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 in at least one direction, such as all directions, at room temperature (20 °C) and 50% relative humidity.

[0115] Various references have been made to the scope of this specification, including temperature ranges. To avoid any 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. Temperature range limitations, for example, any upper or lower limit of any one or more temperature ranges of the heating zones, heaters, or susceptors described above, may be predetermined. The limits may be stored in the controller or in memory, for example, in the controller's memory. 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 temperature of the component can be estimated by monitoring the electrical resistance of the component and comparing it with a temperature-versus-electrical resistance dataset, rather than the temperature of the component.

[0116] 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]

[0117] 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.

[0118] Example 1. 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 the usage session, and the device is configured to raise the temperature of the aerosol-forming substrate from the standby temperature when the user inhales smoke. Example 2. The aerosol generator according to Example 1, 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 3. The aerosol generator according to Example 1 or Example 2, wherein the device is configured to heat an 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 4. The aerosol generator according to Example 3, wherein the operation of 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 5. An aerosol generator according to any one of Examples 1 to 4, wherein the device is configured to heat an 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 6. An aerosol generator configured to generate an aerosol from an aerosol-forming substrate, wherein 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 a user can inhale air when using the device, the airflow path connecting the cavity to the external environment, and the device comprises flow detection means, for example, a pressure sensor located in communication with the airflow path upstream of the cavity, and the device is configured to use signals from the pressure sensor to detect one or more user smoke inhalations performed during a usage session, for example, the aerosol generator described in any of Examples 1 to 5. Example 7. An aerosol generator configured to generate an aerosol from an aerosol-forming substrate, wherein 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 a user can inhale air when using the device, the airflow path connecting the cavity to the external environment, the device comprises a smoke-absorbing sensing element having a pressure sensor located in communication with the airflow path upstream of the cavity and a flow limiter located within the airflow path, and the device further comprises a flow meter located upstream of the pressure sensor, the smoke-absorbing sensing element can be calibrated using measurements from the flow meter, for example, the aerosol generator described in any of Examples 1 to 6. Example 8. The aerosol generator according to Example 7, wherein the flow limiter is a variable flow limiter. Example 9. An aerosol generator according to any one of Examples 1 to 8, wherein the airflow path upstream of the cavity acts as a flow limiter, or is equipped with a flow limiter, for example, the flow limiter comprises a mechanical element located in the airflow path, for example, an orifice plate located in the airflow path. Example 10. The aerosol generator according to Embodiment 9, wherein the flow limiter is a variable flow limiter, and for example the flow limiter is an adjustable valve, and the flow limiter is equipped with user-operable valve means such as an adjustable screw. Example 11. 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 1 to 10, having a cross-sectional area less than [amount missing]. Example 12. An aerosol generator according to any one of Examples 1 to 11, wherein the airflow path upstream of the cavity has a draw-out resistance (RTD) greater than 10 mmH2O, for example, 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 13. An aerosol generator according to any of Examples 1 to 12, wherein the pressure sensor is located upstream of the cavity but downstream of the flow limiter. Example 14. The aerosol generator according to Example 13, wherein the airflow path upstream of the cavity comprises a flow limiter and an expansion zone downstream of the flow limiter, and a pressure sensor is located in the expansion zone. Example 14A. The aerosol generator according to Example 14, 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 15. An aerosol generator according to any one of Examples 1 to 14, wherein the airflow path has 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 forming a flow limiter, and preferably a pressure sensor located in the second portion. Example 15a. The aerosol generator according to Example 15, wherein the airflow path has a channel having an inlet portion having an inlet cross-sectional area, and the inlet cross-sectional area is larger than the first cross-sectional area. Example 15b. The aerosol generator according to Example 15 or Example 15a, wherein the airflow path has an upstream section having an upstream cross-sectional area, a central section having a central cross-sectional area, and a downstream section having a downstream cross-sectional area. Example 15c. The aerosol generator according to Example 15b, wherein the inlet is the upstream section, the first section is the central section, and the second section is the downstream section. Example 16. The aerosol generator according to any one of Examples 15 to 15c, wherein the airflow path upstream of the cavity further comprises a third portion having a third cross-sectional area, the third cross-sectional area being smaller than the second cross-sectional area, for example, the third portion forming a second flow limiter. Example 17. An aerosol generator according to any one of Examples 1 to 16, wherein the airflow path upstream of the cavity comprises a first flow limiter and a second flow limiter, and a pressure sensor is located between the first flow limiter and the second flow limiter, for example, in an expanded portion or expanded chamber located between the first flow limiter and the second flow limiter. Example 18. The aerosol generator according to any of Examples 1 to 17, wherein the device comprises multiple air intakes, each air intake being associated with an airflow path leading to a cavity, thereby enabling airflow into the cavity. Example 19. The aerosol generator according to Example 18, wherein each air intake is associated with an airflow path upstream of the cavity, and a pressure sensor is located in one of the airflow paths. Example 19A. The aerosol generator according to Example 18 or Example 19, wherein multiple air intakes supply airflow paths into an expanded cavity located downstream of the inlet and upstream of the cavity, and a pressure sensor is located within the expanded cavity. Example 19B. The aerosol generator according to Example 19A, wherein the total cross-sectional area of ​​the multiple inlets is smaller than the cross-sectional area of ​​the expanded cavity. Example 19C. The aerosol generator according to Example 19B, wherein the airflow path through multiple inlets upstream of the expanded cavity containing the pressure sensor has 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. Example 20. An aerosol generator according to any one of Examples 1 to 19, comprising a second pressure sensor configured to sense ambient pressure. Example 21. The aerosol generator according to any one of Examples 1 to 20, wherein the airflow path is defined by a channel that extends partially adjacent to or in contact with a heater, for example, the airflow path extends in thermal contact with a heater configured to heat an aerosol-forming substrate located within a cavity. Example 22. The purpose of the flow limiter and / or the first flow limiter and / or the second flow limiter is to accelerate the airflow caused by user smoke extraction, as described in any of Examples 1 to 21. Example 23. The aerosol generator according to any one of Examples 1 to 22, wherein the device is equipped with a pressure sensor, and the pressure sensor is an absolute pressure sensor, such as a piezoresistive pressure sensor. Example 24. An aerosol generator according to any one of Examples 1 to 23, wherein the device comprises a pressure sensor, for example, a pressure sensor located at a flow limiter in the airflow path or located downstream of a flow limiter in the airflow path, which is arranged to detect a pressure drop in the airflow path created when a user inhales smoke. Example 25. An aerosol generator according to any one of Examples 1 to 24, wherein the device is configured to generate an aerosol from an aerosol-forming substrate during a usage session which has a start and an end to the usage session. Example 26. The aerosol generator according to Example 25, 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 27. The aerosol generator according to Example 26, wherein the device 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, and a signal from a pressure sensor is used to control the temperature to the standby target temperature or the operating target temperature. Example 27a. The aerosol generator according to Example 26, wherein the device 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, and a signal from a pressure sensor is used to determine whether to use the standby target temperature or the operating target temperature to control the temperature of the aerosol-forming substrate. Example 28. The aerosol generator according to Example 27, wherein the device is configured to control the temperature of an aerosol-forming substrate with reference to a standby target temperature during non-fumigation periods and with respect to an operating target temperature during fumigation periods. Example 29. An aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, wherein the device 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, the standby target temperature being higher than room temperature and the operating target temperature being higher than the standby target temperature, the device is configured to heat the aerosol-forming substrate to the standby temperature during a usage session, the device is further configured to heat the aerosol-forming substrate from the standby target temperature to the operating target temperature during user smoke inhalation performed during a usage session, and the aerosol generator is configured to generate an aerosol from an aerosol-forming substrate during a usage session, for example, the aerosol generator described in any of Examples 1 to 28. Example 30. An aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, for example, the aerosol generator described in any of Examples 1 to 29, wherein the device 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, the standby target temperature being higher than room temperature and the operating target temperature being 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 performing smoke absorption, the non-smoke absorption period is defined as any period during a usage session in which the user is not actively performing smoke absorption, the device is configured to operate in standby mode during the non-smoke absorption period, and when operating in standby mode, the temperature of the aerosol-forming substrate is controlled with reference to the standby target temperature, and the device is configured to operate in operating mode during the smoke absorption period, and when operating in operating mode, the temperature of the aerosol-forming substrate is controlled with reference to the operating target temperature. Example 31. An aerosol generator configured to generate an aerosol from an aerosol-forming substrate during a usage session, wherein the device is configured to heat an aerosol-forming substrate during a usage session according to a standby mode or an operating mode, wherein the temperature of the aerosol-forming substrate is controlled with respect to a standby target temperature during standby mode, and the temperature of the aerosol-forming substrate is controlled with respect to an operating target temperature during operating mode, wherein the standby target temperature is higher than room temperature and the operating target temperature is higher than the standby target temperature, and the operation of 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, for example, the aerosol generator described in any of Examples 1 to 30. Example 32. The aerosol generator according to Embodiment 31, wherein the smoke inhalation period is defined as any period during a usage session in which the user is actively inhaling smoke, the non-smoke inhalation period is defined as any period during a usage session in which the user is not actively inhaling smoke, the device is configured to operate in standby mode during the non-smoke inhalation period, and the device is configured to operate in operating mode during the smoke inhalation period. Example 33. An aerosol generator according to any one of Examples 1 to 32, wherein the standby target temperature is too low to release substantial aerosols from the aerosol-forming substrate. Example 34. An aerosol generator according to any of Examples 1 to 33, wherein the standby target temperature is lower than the effective boiling point of the aerosol-forming body or aerosol-forming body mixture of the aerosol-forming substrate, for example, lower than the boiling point of propylene glycol used as an aerosol-forming body in the aerosol-forming substrate, or lower than the boiling point of glycerol, or lower than the boiling point of a specific mixture of propylene glycol and glycerol. Example 35. An aerosol generator according to any one of Examples 1 to 34, 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 36. An aerosol generator according to any one of Examples 1 to 35, 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 37. An aerosol generator according to any one of Examples 1 to 36, wherein the target operating temperature is a temperature sufficiently high to release aerosols from the aerosol-forming substrate. Example 38. An aerosol generator according to any of Examples 1 to 37, wherein the target operating temperature is higher than the effective boiling point of the aerosol-forming body or a mixture of aerosol-forming bodies of the aerosol-forming substrate, for example, higher than the boiling point of propylene glycol used as an aerosol-forming body in the aerosol-forming substrate, or higher than the boiling point of glycerol, or higher than the boiling point of a specific mixture of propylene glycol and glycerol. Example 39. An aerosol generator according to any one of Examples 1 to 38, 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 40. An aerosol generator according to any of Examples 1 to 39, wherein the target operating temperature is 160°C to 400°C, for example 180°C to 340°C, or for example 220°C to 300°C. Example 41. An aerosol generator according to any one of Examples 1 to 40, wherein the standby target temperature remains constant throughout the entire duration of the usage session. Example 42. An aerosol generator according to any of Examples 1 to 40, other than Example 41, wherein the standby target temperature changes over the duration of the usage session. Example 43. An aerosol generator according to any of Examples 1 to 42, wherein the target operating temperature remains constant throughout the entire duration of the usage session. Example 44. An aerosol generator according to any of Examples 1 to 42 other than Example 43, wherein the target operating temperature changes over the duration of the usage session, for example, the target operating temperature changes with each smoke extraction. Example 45. An aerosol generator according to any one of Examples 1 to 44, 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 46. An aerosol generator according to any one of Examples 1 to 45, 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 reference to a standby target temperature during the non-smoke absorption period and with respect to an operating target temperature during the smoke absorption period. Example 47. The aerosol generator according to Example 46, 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 48. An aerosol generator according to any one of Examples 1 to 47, wherein the usage session has a predetermined duration set, for example, with reference to time, or with reference to usage parameters, or with reference to both time and usage parameters. Example 49. The aerosol generator according to Example 48, wherein the parameters used are selected from a list consisting of the number of user smoke inhalations performed during the usage session, the amount of aerosol generated during the usage session, and the power supplied to the heater during the usage session. Example 50. An aerosol generator according to any one of Examples 1 to 49, wherein the device is configured to detect one or more user inhalations that occurred during a usage session. Example 51. An aerosol generator according to any one of Examples 1 to 50, 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 52. An aerosol generator according to any one of Examples 1 to 51, wherein the device is configured to detect the initiation of user inhalation during a usage session, for example, each user inhalation performed during a usage session. Example 53. An aerosol generator according to any one of Examples 1 to 52, wherein the device is configured to detect the end of user inhalation performed during a usage session, for example, each user inhalation performed during a usage session. Example 54. An aerosol generator according to any one of Examples 1 to 53, wherein the device is configured to determine the duration of user inhalation during a usage session, for example, each user inhalation during a usage session. Example 55. An aerosol generator according to any one of Examples 1 to 54, wherein the device is configured to characterize user smoke inhalation performed during a usage session, for example, each smoke inhalation performed during a usage session. Example 56. The aerosol generator according to Example 55, wherein the device is configured to characterize user inhalation detected during a usage session, for example, each user inhalation detected during a usage session. Example 57. The aerosol generator according to Example 55 or Example 56, wherein the device is configured to determine the amount of aerosol generated during user inhalation performed during a usage session, for example, during each user inhalation performed during a usage session. Example 58. An aerosol generator according to any one of Examples 1 to 57, wherein the device comprises a pressure sensor for use in detecting one or more user inhalations that occurred during a usage session. Example 59. The aerosol generator according to Example 58, wherein a pressure sensor detects a change in pressure in the airflow path as a result of the user performing smoke inhalation, for example, smoke inhalation 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 inhalation. Example 59a. The aerosol generator according to Example 58, wherein a pressure sensor detects a change 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 the pressure of the airflow path as a result of the user performing smoke extraction. Example 60. An aerosol generator according to any of Examples 1 to 59, wherein the device defines an airflow path from which the user can inhale air when using the device. Example 61. An aerosol generating apparatus according to any one of Examples 1 to 60, wherein the apparatus defines a cavity having an opening for receiving at least a portion of an aerosol-forming substrate. Example 62. The aerosol generator according to Example 61, wherein the device defines an airflow path upstream of a cavity from which a user can inhale air when using the device, and the airflow path connects the cavity to the external environment. Example 63. An aerosol generator according to any one of Examples 1 to 62, wherein the device is equipped with a power supply. Example 64. An aerosol generator according to any one of Examples 1 to 63, wherein the apparatus comprises a heater for heating an aerosol-forming substrate. Example 65. An aerosol generator according to any one of Examples 1 to 64, wherein the apparatus includes 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 66. The aerosol generator according to any one of Examples 1 to 65, 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 within the device. Example 67. The aerosol generator according to any one of Examples 1 to 66, 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 device such that the heated air acts to heat the aerosol-forming substrate received into the device. Example 68. The aerosol generator according to any one of Examples 1 to 67, comprising a controller for controlling the generation of aerosols, for example, a controller that communicates with a power supply and a heater. Example 69. An aerosol generator according to any one of Examples 1 to 68, wherein the device comprises a resistance heater disposed to heat an aerosol-forming substrate received in a cavity of the device. Example 70. An aerosol generator according to any one of Examples 1 to 69, wherein the device comprises an induction heater disposed to heat an aerosol-forming substrate received in a cavity of the device, and for example, the device comprises an inductor disposed to heat a susceptor that is in thermal communication with the aerosol-forming substrate received in a cavity of the device. Example 71. An aerosol generator according to any one of Examples 1 to 70, wherein the device is configured to determine the temperature of the aerosol-forming substrate during use. Example 72. An aerosol generator according to any one of Examples 1 to 71, comprising a controller configured to determine the temperature of an aerosol-forming substrate during use, wherein the temperature is determined by monitoring the behavior of a heater during use, for example, by monitoring the apparent resistance or apparent conductance of the heater. Example 73. An aerosol generator according to any one of Examples 1 to 72, wherein the apparatus comprises 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 temperature control element. Example 74. An aerosol generator according to any one of Examples 1 to 73, wherein the apparatus 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 75. An aerosol generator according to any one of Examples 1 to 74, wherein, upon use, the aerosol generator determines the start of a usage session and enters a standby mode in which the aerosol-forming substrate received in the device is heated; during the standby mode, the temperature of the aerosol-forming substrate is controlled with reference to a standby target temperature; the aerosol generator detects user smoke inhalation performed during the usage session and, in response to the detected user smoke inhalation, enters an operating mode in which greater thermal energy is supplied to the aerosol-forming substrate to raise its temperature; and 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. Example 76. The aerosol generator described in Example 75 comprises one or more power sources, one or more heaters, and a controller, the controller being configured to enter standby mode at the start of an operating session, to detect the start of user inhalation and switch from standby mode to operating mode in response to the detection of the start of user inhalation, to 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. Example 77. The aerosol generator according to Example 75 or Example 76, wherein the controller increases the power supplied to one or more heaters during operation mode compared to standby mode. Example 78. An aerosol generator according to any one of Examples 75 to 76, wherein the device comprises a first heater and a second heater, the first heater being arranged to heat an aerosol-forming substrate during standby mode, and the second heater not being arranged to heat an aerosol-forming substrate during standby mode. Example 79. An aerosol generator according to any one of Examples 75 to 78, wherein the apparatus comprises a first heater and a second heater, and both the first heater and the second heater are arranged to heat an aerosol-forming substrate during the operating mode. Example 80. An aerosol generator according to any one of Examples 78 to 79, 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 81. An aerosol generating system comprising an aerosol generating device described in any of Examples 1 to 80 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 generating device. Example 82. The aerosol generating system according to Example 81, wherein the aerosol-forming article comprises a plurality of components including an aerosol-forming substrate assembled within a wrapper. Example 83. An aerosol generating system according to Example 81 or Example 82, wherein the aerosol generating article has a drawdown resistance (RTD) of 10 mmH2O to 50 mmH2O. Example 84. The system airflow path is defined through the apparatus and the aerosol generating article when the aerosol generating article is received into the apparatus, and for example, the system airflow path includes an airflow path defined through the apparatus and an airflow path defined through the aerosol generating article, and for example, the system airflow path has a drawdown resistance (RTD) of 20 mmH2O to 100 mmH2O, as described in the aerosol generating system of Example 81 or Example 82. Example 85. 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 inhale air when using the device, the airflow path connecting the cavity to an external environment; and a pressure sensor positioned in communication with the airflow path upstream of the cavity, the method comprising: arranging an aerosol-forming substrate in the cavity; operating the device; detecting a pressure change in the airflow path associated with the start of user inhalation; detecting a pressure change in the airflow path associated with the end of user inhalation; and thereby detecting user inhalation. Example 86. 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 inhale air when using the device, the airflow path connecting the cavity to an external environment; and a pressure sensor positioned in communication with the airflow path upstream of the cavity, the method comprising: arranging an aerosol-forming substrate in the cavity; operating the device 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. Example 87. A method for manipulating an aerosol using an aerosol generator, 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 a user can inhale air when using the device, the airflow path connecting the cavity to an external environment, wherein the method comprises the steps of: arranging the aerosol-forming substrate in the cavity; operating the device in a standby mode in which the temperature of the aerosol-forming substrate is controlled with reference to a standby target temperature; switching the mode of operation from the standby mode to an operating mode in response to user inhalation of smoke, wherein the operating target temperature is higher than the standby target temperature. Example 88. A method for generating the aerosol described in Example 85, Example 86, or Example 87, using an apparatus defined in any of Examples 1 to 80, or a system defined in any of Examples 81 to 84. [Brief explanation of the drawing]

[0119] The present invention will be further described, for illustrative purposes only, with reference to the attached drawings.

[0120] [Figure 1] Figure 1 shows a schematic cross-sectional view of a portion of the aerosol generator. [Figure 2] Figure 2 shows the aerosol generating device of Figure 1 in engagement with the 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, illustrating 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, illustrating 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 one embodiment of the present invention, configured as a test apparatus with 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 an 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 when 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 projection 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 projection 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 projection view of the heater assembly shown in Figure 15. [Modes for carrying out the invention]

[0121] Figure 1 shows a schematic cross-sectional view illustrating a portion of the aerosol generator 1. The device 1 includes an open end 12 into which a portion of the aerosol generating article can be inserted into a heating chamber 2. The heating chamber 2, which may also be called a heating cavity, is sized to receive a portion of the 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, providing thermal energy to heat the chamber 2 and any contents within the chamber. In an 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 area of ​​heating surface to efficiently heat the passing air. 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.

[0122] The chamber 2, the first heater 3, the second heater 4, and the airflow path 6 are located within the housing 77. The housing also includes a power source, such as a battery, and a controller positioned to control the power supply from the power source to the first and second heaters. Although the battery and controller are not shown in Figure 1, the arrangement of such components within the housing of an aerosol generator is well known.

[0123] Figure 2 illustrates the same portion 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 the paper wrapper of a cigarette. This typical aerosol generating article 200 resembles a conventional cigarette. When in use, the front or distal end of the aerosol generating article 200 is inserted into the chamber 2 of the aerosol generator 1, with the aerosol-forming substrate 201 positioned within the chamber 2. The mouth-side or proximal end of the aerosol generating article protrudes from the chamber 2, thereby allowing the user to inhale the mouth-side end of the article 200. When a user inhales the mouth end of an article 200 located inside chamber 2, air enters the inlet of the device, through the airflow path 6, through the second heater 4, into chamber 2, through the aerosol-forming substrate 201 of the article 200, and is drawn into the user's mouth. When the aerosol-forming substrate is heated above its aerosolization temperature, volatile components of the aerosol-forming substrate may volatilize. These volatile components are drawn into the airflow when the user inhales the article, condense to form an inhalable aerosol that can be consumed by the user.

[0124] 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 heating profiles is provided as Figure 3. When the article 200 is inserted into the chamber 2 of the apparatus and a use session begins, the controller 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 rises 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 also be called the maintenance temperature, and the first heater may also be called the maintenance heater.

[0125] The temperature of the aerosol-forming substrate may be measured directly with a temperature sensor. Alternatively, the substrate temperature may be determined by monitoring the electrical parameters of the heater, such as the heater's resistance or the power supplied to the heater.

[0126] The second heater 4 may be activated at the start of a usage session, or only when the user inhales. When the user inhales the item 200, air is drawn in 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 raises 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 called a boost heater. The temperature may be controlled to a second temperature higher than the standby target temperature 310. This second temperature may be called 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, forming an aerosol containing these components.

[0127] Therefore, the temperature of the aerosol-forming substrate is maintained at a temperature slightly below the aerosolization temperature using a maintenance heater, and then rises to a temperature above the aerosolization temperature when the user inhales smoke. This offers the advantage that the aerosol-forming substrate consumes its aerosol-forming components only when the user inhales smoke, which can reduce the amount of aerosol-forming material used in the article. If the boost heater is activated only during user inhalation, the dual heating mode configuration can provide energy savings over the duration of the usage session.

[0128] 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 high-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 further examples, 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 variation, 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 capacitive or dielectric heaters.

[0129] Figure 4 illustrates 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 controller 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 in the sensing portion 9 where the pressure sensor 7 is located than in the restricting portion 8 upstream of the sensing portion 9. In this exemplary embodiment, the air intake 87 has a transverse upstream cross-sectional area at section line A1, the restricting portion 8 has a transverse central cross-sectional area at section line A2, and the sensing portion 9 has a transverse downstream cross-sectional area at section A3. The upstream cross-sectional area is larger than the central cross-sectional area. The downstream cross-sectional area is larger than the central cross-sectional area. The air intake 87, restricting portion 8, and sensing portion 9 are continuous sections along the flow direction of the continuous airflow path 6. The limiting portion 8 of the channel 80 defining the airflow path 6 acts as a limit on the airflow path, causing a pressure drop in the sensing portion when the user inhales air through the airflow channel 80. Therefore, the limiting portion 8 can be called a flow limiter. This pressure drop may be detected by a pressure sensor, from which a signal is sent to the controller, thereby enabling the detection of the start and end of user smoke inhalation. The pressure drop resulting from user smoke inhalation increases within the region of the limit due to the increase in 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 raise the pressure signal resulting from user smoke inhalation above background noise, which helps to enable detection of user smoke inhalation using a single sensor. Placing the pressure sensor just downstream of the limit in this way improves the sensitivity of user smoke inhalation detection.

[0130] During use, the aerosol generating article 200 is inserted into the chamber 2, and the device is activated. This initiates a usage session. The first heater 3 is rapidly heated to its standby operating target temperature, for example, 170°C as described above. Next, the user inhales or breathes through the mouthpiece 204 of the article 200. This results in an airflow that passes through the air intake 87 of the device, through the flow limiting section 8, through the second heater 4, then through the article 200, and then into the user's mouth.

[0131] The flow limiter 8 reduces the cross-sectional area of ​​the airflow path of the device. Therefore, when 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 transmitted to the device controller continuously or at frequent intervals, such as every 50 milliseconds. When the pressure inside the flow limiter drops significantly, smoke extraction is detected.

[0132] In response to the detection of smoke extraction, the controller 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, raising the temperature of the aerosol-forming substrate from a standby target temperature of 170°C to an operating target temperature of 250°C. This heats the aerosol-forming substrate 201 above the aerosolization temperature of the aerosol-forming substrate 201 that forms aerosols.

[0133] Note that the second heater may be started from the beginning of the usage session, in which case the controller may supply greater power to the second heater in response to detection of user smoke inhalation.

[0134] 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 controller 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.

[0135] 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.

[0136] Figure 5 illustrates a portion of an aerosol generator 501 having an alternative airflow path configuration. The device 501 is shown engaged with an aerosol generating article 200. The device 501 is substantially identical to the devices illustrated in Figures 1-4, and common components are given the same reference numerals in Figure 5.

[0137] 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 the first heater 3 in thermal contact before opening to the second heater 4 located upstream of the chamber 2. Air drawn into the airflow path 506 through the inlet 587 passes through the orifice plate 518 and the pressure sensor 507 before entering the second heater 4 and then the chamber 2. The orifice plate 518 forms a restriction in the airflow path 506, causing a pressure drop detectable at the location of the sensor 507 when the user is inhaling smoke.

[0138] During use, the device 501 operates in a similar manner to the device described above with respect to Figure 4. The air flowing in along the channel 580 is heated to some extent by the first heater 3, thereby recovering some of the thermal energy that could have been lost from the system into the air flowing through the device and transferring it to the aerosol-forming substrate 201 of the article 200 located in the chamber 2.

[0139] Different aerosol-generating articles may provide different draw-to-discharge (RTDs). This can change the overall RTD of the system (i.e., the RTD of the combination of aerosol generator and aerosol-generating article). It may be desirable to adjust the pressure drop caused by the limit to optimize smoke extraction detection for a particular system. Therefore, it may be desirable to provide a test apparatus that can determine the optimal dimensions of the limit and calibrate the pressure sensor for a particular system.

[0140] Figure 6 illustrates 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 limiting section. It should be noted that many other forms of the variable flow limiter, such as 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 using the flow meter to know the actual flow through the system, the signal from the pressure sensor can be calibrated. By using variable limits, the effect of different pressure drops on the sensitivity of a pressure sensor can be evaluated. When appropriate limit dimensions are selected, aerosol generators with fixed limits can be manufactured without the need for flow meters.

[0141] 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 is 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 may 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 disposed such that when the 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.

[0142] 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.

[0143] The first resistance heater 740 is positioned in contact with the outer surface 727 of the hollow body 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 maintenance heating to the aerosol-forming substrate located in the chamber 716 by maintaining the substrate temperature at a standby target temperature lower than the substrate's aerosolization temperature.

[0144] 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 located in 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. It should be noted 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.

[0145] Figure 8 illustrates a portion of the aerosol generator 800, which includes the heater assembly 712 shown in 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 located 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.

[0146] When in use, the apparatus 800 in Figure 8 functions in the same manner as described above with respect to the apparatus in Figure 4. That is, when the aerosol generator is inserted into the chamber 716 and the apparatus is activated, a usage session begins. 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 smokes through the mouthpiece 204 of the article 200. This results in an airflow that passes through the air intake 887 of the apparatus, 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 controller receives a signal from the pressure sensor 807 indicating that user inhalation is taking place. 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.

[0147] The heater assembly 712 described in relation to Figure 7 utilizes a resistance heater placed 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 are then directly attached to parts of the heater assembly to heat those parts of the heater assembly. An example is shown in Figure 9.

[0148] Figure 9 is a schematic diagram of a heater assembly 912 formed from a conductive and resistance-heatable polymer 901. Polymer 901 is a polymer composite comprising a polymer matrix and conductive filler particles. In certain embodiments, polymer 901 comprises a polymer material and at least one particulate filler selected from the list consisting of graphite, graphite-derived materials, and hexagonal boron nitride, the filler being dispersed within the polymer material. In certain embodiments, the polymer material forming the matrix is ​​polyetheretherketone (PEEK), but may instead be liquid crystal polymer (LCP). Polymer 901 contains 27 weight percent of the polymer material, although this amount may be between 22 and 33 percent. Polymer 901 contains 65 weight percent of the filler, although this may be between 62 and 69 percent. Polymer 901 further contains carbon black, an additive dispersed within the polymer material. Polymer 901 contains 7 weight percent of the additive, although this may be between 5 and 9 percent.

[0149] A heating body 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 bodies configured for resistance heating. In particular, the thermoplastic properties of the polymer matrix may allow the polymer composite to be conveniently made malleable, thereby allowing the polymer composite to take on a precise and controlled shape. 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 the conductive filler particles dispersed within the polymer matrix, it is possible to provide a polymer heating body that can generate sufficient heat by resistance heating to efficiently heat the solid aerosol generating substrate of an aerosol generating article thermally bonded to the heating body. For example, by adjusting the formulation of the polymer matrix and the degree of dispersion of the 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 body.

[0150] 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. Then, granulated polymer is placed at one end of the tube and lightly sintered to form a porous plug 934 that hangs over the other end of the tube. The granulated polymer particles that are 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.

[0151] The resulting heater assembly 912 has an opening 918 at one end and connects to a chamber 916 defined by an inner wall 922.

[0152] 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 act of passing current through a portion of the heater assembly heats the heater assembly wall and supplies heat to the aerosol generating substrate located within the cavity. Therefore, the wall of cavity 930 can act as a first heater to provide maintenance heating to the substrate located within the cavity.

[0153] 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 resistance heating of the heater assembly wall and the porous plug. 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.

[0154] 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.

[0155] Figure 10 illustrates 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 may be inserted into the chamber 1016) and a closed end 1020 opposite the open end 1018.

[0156] 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 so that when the aerosol-generating article is inserted into the chamber 1016, the aerosol-generating article is received within the tubular element 1028 and is in direct contact with the tubular element 1028. The tubular element is formed from a ceramic material, such as alumina.

[0157] 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 the user inhales the smoke, the porous plug only affects the temperature of the article.

[0158] 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 located 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.

[0159] The first resistance heater 1040 is located within the tubular element 1028 in the hollow body 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 maintenance heating to the aerosol-forming substrate located in the chamber 1016 by maintaining the substrate temperature at a standby target temperature lower than the substrate's aerosolization temperature.

[0160] The 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 located 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.

[0161] 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 to provide a gap between an aerosol-forming substrate inserted into the chamber and a porous plug 934 defining the end of the chamber.

[0162] 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 overmolding process. Conductive adhesive may also be used to attach the contacts, for example, HT-carbon adhesive or silver epoxy adhesive. The arrangement of the porous plug 934 over 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 illustrated on the end projection of the heater assembly 1112 shown in Figure 12.

[0163] 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. Heat from the heater assembly within the cavity region can heat the aerosol-forming substrate inserted into the cavity. Heat from the heater assembly within the porous plug 934 region 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.

[0164] Figures 13 and 14 illustrate 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.

[0165] Figures 15 and 16 illustrate 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 the radially opposite portion 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 may be used to supply maintenance heating 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.

[0166] 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 embodiments as being modified by the term “approximately.” Furthermore, all ranges include the disclosed maximum and minimum points and any central range within them, which may or may not be specifically listed herein. Thus, in this context, number A is understood as A ± 10 percent (10%). 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 central range within them, 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 from which the user can inhale air when using the apparatus, the airflow path connecting the cavity to the external environment, The airflow path comprises an upstream section having an upstream cross-sectional area, a central section having a central cross-sectional area, and a downstream section having a downstream cross-sectional area. The upstream cross-sectional area is larger than the central cross-sectional area. The downstream cross-sectional area is larger than the central cross-sectional area. An aerosol generator comprising a pressure sensor located in the downstream section of the upstream airflow path of the cavity, wherein the device is configured to use a signal from the pressure sensor to detect one or more user inhalations performed during use of the device.

2. The aerosol generating apparatus according to claim 1, wherein the airflow path upstream of the cavity acts as a flow limiter or is equipped with a flow limiter.

3. The aerosol generator according to claim 2, wherein the flow limiter comprises a mechanical element located within the airflow path, for example, an orifice plate located within the airflow path.

4. The aerosol generator according to claim 2 or 3, wherein the flow limiter is a variable flow limiter, for example, the flow limiter is an adjustable valve.

5. A portion of the airflow path upstream of the cavity is 0.5 mm 2 Less than, for example, 0.4 mm 2 An aerosol generator according to any one of claims 1 to 4, having a cross-sectional area less than [amount missing].

6. The airflow path upstream of the cavity is 10 mmH 2 0-50mmH 2 An aerosol generator according to any one of claims 1 to 5, having an O drawout resistance (RTD).

7. The aerosol generator according to any one of claims 1 to 6, 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, and the device is configured to detect one or more user smoke inhalations performed during the usage session.

8. The aerosol generator according to any one of claims 1 to 7, wherein the device is configured to distinguish between a smoke inhalation period and a non-smoke inhalation period, the smoke inhalation period being defined as any period during a usage session in which the user is actively inhaling smoke, and the non-smoke inhalation period being defined as any period during a usage session in which the user is not actively inhaling smoke.

9. The aerosol generator according to any one of claims 1 to 8, wherein the device is configured to characterize user smoke inhalation performed during use, for example, each smoke inhalation performed during a usage session.

10. The aerosol generator according to claim 9, wherein the device is configured to characterize user inhalation detected during the usage session, for example, each user inhalation detected during the usage session.

11. The aerosol generator according to claim 9 or 10, wherein the device is configured to determine the amount of aerosol generated during user inhalation or during each user inhalation, for example, during each user inhalation performed during the usage session.

12. The aerosol generator according to any one of claims 1 to 11, wherein the pressure sensor detects a change in the flow path of the airflow as a result of the user inhaling smoke, for example, the smoke inhalation involves the user inhaling air through a part of the device along the airflow path, and the pressure sensor detects a change in the pressure of the airflow path as a result of the user inhaling smoke.

13. The aerosol generator according to any one of claims 1 to 12, wherein the apparatus 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, the operating target temperature is higher than the standby target temperature, and a signal from the pressure sensor is used to determine whether to use the standby target temperature or the operating target temperature to control the temperature of the aerosol-forming substrate.

14. An aerosol generating system comprising an aerosol generating device according to any one of claims 1 to 13, 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 generating device.

15. A method for generating an aerosol using an aerosol generator, wherein the aerosol generator is 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 inhale air when using the device, the airflow path connecting the cavity to the external environment, The method comprises a pressure sensor positioned in communication with the airflow path upstream of the cavity, and the method A step of placing an aerosol-forming substrate in the cavity, A step of operating the aforementioned device, A step of detecting a pressure change in the airflow path associated with the initiation of user smoke inhalation, A method comprising the steps of detecting a pressure change in the airflow path associated with the termination of user smoke inhalation, and detecting user smoke inhalation by means of such change.

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