Aerosol-generating device and system and control method thereof

Abstract

An aerosol-generating device and a method of controlling aerosol generation in the aerosol-generating device are provided. The method comprises: receiving an aerosol-generating article from a heating chamber of the aerosol-generating device, where an aerosol-forming substrate of the aerosol-generating article has a total aerosol former content of greater than 30% by weight, and where the aerosol-forming substrate is a solid or a gel; and heating the aerosol-forming substrate to form an aerosol for inhalation by a user by controlling the power: increasing a temperature of the heating element from an initial temperature to a first temperature; and maintaining the temperature of the heating element constant at the first temperature for a duration of a first predetermined time period, wherein the first temperature is between 245 DEG C and 285 DEG C.

Description

[0001] The present disclosure relates to a method of controlling aerosol generation in an aerosol generating device configured to heat an aerosol generating article comprising a solid or gel aerosol-forming substrate. The present disclosure also relates to an aerosol generating device and a system comprising the aerosol generating device and the aerosol generating article.

[0002] The aerosol generating device may comprise an electrically operated heat source configured to heat an aerosol generating article comprising an aerosol-forming substrate to generate an aerosol. Typically, in a heated aerosol generating article, an aerosol is generated by transferring heat from a heat source to a physically separated aerosol-forming substrate. In use, volatile compounds are released from the aerosol-forming substrate by heat transfer from the heat source to the aerosol-forming substrate and are entrained in air drawn through the aerosol generating article. As the released compounds cool, the compounds condense to form an aerosol that is inhaled by a user.

[0003] Many hand-held aerosol generating devices configured to heat an aerosol-forming substrate of a heated aerosol-generating article are known in the art. These devices include electrically operated aerosol generating devices, wherein an aerosol is generated by transferring heat from one or more electrical heating elements of the aerosol generating device to the aerosol-forming substrate of the heated aerosol generating article. Known hand-held electrically operated aerosol generating devices typically include a battery, control electronics, and one or more electrical heating elements for heating the aerosol-forming substrate of the heated aerosol generating article.

[0004] It is desirable to provide an aerosol generating device and a method of controlling aerosol generation in an aerosol generating device, wherein a high amount of volatile compounds is delivered to the user from the first puff, and wherein good delivery of volatile compounds is maintained throughout the user experience.

[0005] According to an embodiment, a method of controlling aerosol generation in an aerosol generating device is provided. The device includes: a heating chamber configured to at least partially receive an aerosol generating article including an aerosol-forming substrate; a heating system associated with a heating element configured to heat the aerosol-forming substrate internally from within the aerosol-forming substrate; and a power source for providing power to the heating system. The method includes: receiving the aerosol generating article by the heating chamber, wherein the aerosol-forming substrate has a total aerosol-forming agent content greater than 30% by weight, and wherein the aerosol-forming substrate is a solid or a gel; and heating the aerosol-forming substrate to form an aerosol for inhalation by a user by controlling the power to perform the following operations: increasing the temperature of the heating element from an initial temperature to a first temperature; and maintaining the temperature of the heating element constant at the first temperature for a duration of a first predetermined time period, wherein the first temperature is between 245 degrees Celsius and 285 degrees Celsius.

[0006] By heating the heating element to within this temperature range for a first predetermined period of time, the thermal inertia of the aerosol-forming substrate is overcome and the amount of vaporized desired volatile compounds in the aerosol inhaled by the user is improved from the first puff.

[0007] As used herein with reference to the present invention, the term "aerosol generating device" is used to describe a device that interacts with the aerosol-forming substrate of an aerosol-generating article to generate an aerosol.The aerosol generating device may be a handheld, electrically operated device.

[0008] As used herein with reference to the present invention, the term "aerosol-generating article" is used to describe an article comprising an aerosol-forming substrate, which is heated to generate an inhalable aerosol for delivery to a user. The aerosol-generating article may be disposable.

[0009] As used herein with reference to the present invention, the term "aerosol" is used to describe a dispersion of solid particles or liquid droplets, or a combination of solid particles and liquid droplets, in a gas. Aerosols may be visible or invisible. Aerosols may include vapors of substances that are normally liquid or solid at room temperature, as well as solid particles or liquid droplets, or a combination of solid particles and liquid droplets.

[0010] As used herein with reference to the present invention, the term "aerosol-forming substrate" is used to describe a substrate comprising an aerosol-generating material which is capable of releasing volatile compounds which can generate an aerosol upon heating.

[0011] Preferably, the power source is a battery, such as a lithium ion battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may need to be recharged. For example, the power source may have sufficient capacity to allow continuous generation of aerosol for a period of about six minutes, or for an integral multiple of six minutes. In another example, the power source may have sufficient capacity to allow a predetermined number of puffs or discontinuous activations of the heating system.

[0012] As used herein with reference to the present invention, the term "aerosol former" is used to describe a compound that, in use, promotes the formation of an aerosol and which is preferably substantially resistant to thermal degradation at the operating temperature of an aerosol-generating article or an aerosol-generating system comprising an aerosol-forming substrate.

[0013] As used herein with reference to the present invention, the term "total aerosol former content" is used to describe the combined content of all aerosol formers in the aerosol-forming substrate.

[0014] Unless stated otherwise, weight percentages of components of an aerosol-forming substrate reported herein are based on the dry weight of the aerosol-forming substrate.

[0015] As used herein with reference to the present invention, the term "solid" is used to describe an aerosol-forming substrate that has a stable size and shape and does not flow at 23°C.

[0016] As used herein with reference to the present invention, the term "gel" is used to describe an aerosol-forming matrix comprising two or more components, one of which is a liquid. A gel is predominantly a liquid by weight. A gel is a substantially dilute cross-linked system that does not exhibit flow in the steady state, but a liquid phase can still diffuse through the system.

[0017] The first time period may have a duration of 40 seconds to 300 seconds, preferably 40 seconds to 150 seconds.

[0018] Controlling the power may also include adjusting the temperature of the heating element to a second temperature during a second predetermined time period, wherein the second predetermined time period is subsequent to the first predetermined time period.

[0019] The second predetermined time period may immediately follow the first predetermined time period.

[0020] The second temperature may be different from the first temperature.

[0021] The second temperature may be lower than the first temperature.

[0022] Lowering the temperature of the heating element in the second heating mode enables the amount of vaporized desired volatile compounds in the aerosol inhaled by the user to remain consistent with the amount during the first predetermined period of time, thereby providing the user with the same sensory experience.

[0023] The second temperature may be between 190 degrees Celsius and 220 degrees Celsius.

[0024] Adjusting the temperature of the heating element to the second temperature during the second time period may include two consecutive temperature steps.

[0025] The temperature of the first temperature step may be lower than the temperature of the second temperature step.

[0026] Having two temperature steps in the second heating mode allows for improved control of the amount of desired volatile compounds evaporated in the aerosol inhaled by the user, thereby providing the user with the same sensory experience. Furthermore, if the temperature of the second heating step is higher than the temperature of the first heating step, the amount of desired evaporated volatile compounds remains consistent, even if the amount of desired volatile compounds is consumed over time with heating.

[0027] Adjusting the temperature of the heating element to a second temperature during the second predetermined time period may include increasing the temperature of the heating element from a first temperature.

[0028] The duration of the second predetermined time period may be between 100 seconds and 280 seconds.

[0029] Controlling the power may also include adjusting the temperature of the heating element to a third temperature during a third predetermined time period, wherein the third predetermined time period is subsequent to the second predetermined time period.

[0030] The third temperature may substantially correspond to the first temperature.

[0031] Performing the heating of the aerosol-forming substrate to form an aerosol for inhalation by a user in three predetermined time periods in which the temperature of the heating element is adjusted to a respective temperature enables improved control of aerosol delivery. In particular, towards the end of the user process in the third predetermined time period, the amount of desired volatile compounds to be vaporized for inhalation by the user will be depleted. Increasing the temperature of the heating element to substantially the first temperature enables the amount of vaporized desired volatile compounds in the aerosol inhaled by the user to remain consistent with the amount in the first and second predetermined time periods.

[0032] The duration of the third predetermined time period may be between 30 seconds and 120 seconds.The third predetermined time period may be immediately after the second predetermined time period.

[0033] The power may be controlled based on a heating curve of a plurality of heating curves, wherein each heating curve defines how the temperature of the heating element is adjusted during each of the time periods.

[0034] The method may further include selecting a heating profile based on identifying the aerosol-generating article.

[0035] The power may be controlled based on a heating curve from a plurality of heating curves, wherein each heating curve may define how the temperature of the heating element is adjusted during the second time period.

[0036] The method may further include selecting a heating profile based on identifying the aerosol-generating article.

[0037] The heating system may include an induction coil configured to inductively heat the heating element.

[0038] As used herein, the term "induction heating" refers to the heating of a heating element (such as a susceptor) when penetrated by an alternating magnetic field. The heating may be caused by the generation of eddy currents in the heating element. The heating may be caused by hysteresis losses.

[0039] The heating element may be a susceptor. As used herein, the term "susceptor" refers to an element comprising a material capable of converting magnetic field energy into heat. When the susceptor is located in an alternating magnetic field, the susceptor is heated. The heating of the susceptor may be a result of at least one of hysteresis losses and eddy currents induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material. The susceptor may be an elongated susceptor. As used herein with reference to the present invention, the term "elongated" is used to describe a susceptor having a length greater than its width. For example, the length of the susceptor may be at least twice its width.

[0040] The method may further include controlling power to increase the temperature of the heating element from the ambient temperature to the initial temperature during a preheating period prior to the first predetermined period.

[0041] The preheat period may have a duration between 10 and 20 seconds.

[0042] The preheating period ensures that, regardless of the physical condition of the aerosol-forming substrate (e.g. dry or wet), the duration of the preheating period is sufficient for the aerosol-forming substrate to reach the minimum operating temperature so as to be ready for continuous power supply and to reach the first operating temperature as quickly as possible for generating sufficient aerosol to be inhaled by the user. This is particularly advantageous for aerosol-forming substrates with a high aerosol-former content (greater than 30 wt %), as such substrates typically have a high moisture content after reaching thermal equilibrium.

[0043] The method may further include calibrating the heating element after the preheating period and before the first predetermined period of time.

[0044] Calibrating the heating element during heating of the aerosol-forming substrate for generating an aerosol (rather than during manufacture) advantageously provides a more accurate determination of the calibration value used in temperature control and thus enables improved temperature control.

[0045] The heating system may further comprise a heating element which is a resistive heating element.

[0046] The method may further include controlling power to increase the temperature of the heating element from the ambient temperature to the initial temperature during a preheating period prior to the first predetermined period.

[0047] The preheat period may have a duration between 10 and 20 seconds.

[0048] The preheating period ensures that, regardless of the physical condition of the aerosol-forming substrate (e.g. dry or wet), the duration of the preheating period is sufficient for the aerosol-forming substrate to reach the minimum operating temperature so as to be ready for continuous power supply and to reach the first operating temperature as quickly as possible for generating sufficient aerosol to be inhaled by the user. This is particularly advantageous for aerosol-forming substrates with a high aerosol-former content (greater than 30 wt %), as such substrates typically have a high moisture content after reaching thermal equilibrium.

[0049] The aerosol-forming substrate may comprise a total aerosol-former content of greater than 35 wt %.The aerosol-forming substrate may comprise a total aerosol-former content of greater than 40 wt %.The aerosol-forming substrate may comprise a total aerosol-former content of greater than 45 wt %.

[0050] The aerosol-forming substrate may comprise one or more aerosol formers selected from 1,3-butanediol, glycerol, 1,3-propanediol, propylene glycol, triethylene glycol, glycerol monoacetate, glycerol diacetate, glycerol triacetate, dimethyl dodecanedioate and dimethyl tetradecanedioate.

[0051] The aerosol-forming substrate may not comprise tobacco.

[0052] The aerosol-forming substrate may also comprise nicotine.

[0053] As used herein with reference to the present invention, the term "nicotine" is used to describe nicotine, nicotine base or nicotine salt. In embodiments where the aerosol-forming substrate comprises nicotine base or nicotine salt, the amount of nicotine recorded herein is the amount of free base nicotine or the amount of protonated nicotine, respectively.

[0054] The aerosol-forming substrate may comprise natural nicotine or synthetic nicotine, or a combination of natural and synthetic nicotine.

[0055] The aerosol-forming substrate may further comprise one or more cellulose-based agents and one or more carboxylic acids selected from fumaric acid, maleic acid and malic acid.

[0056] The aerosol-forming substrate may have a total cellulose-based agent content of at least 35 wt % and a total carboxylic acid content of at least 0.5 wt %.

[0057] As used herein with reference to the present invention, the term "cellulose-based agent" is used to describe a cellulosic material. Examples of cellulose-based agents include cellulose-based film formers, cellulose-based strengthening agents, and cellulose-based binders. For example, where the aerosol-forming substrate comprises a plurality of cellulose-based agents consisting of a cellulose-based film former, a cellulose-based strengthening agent, and a cellulose-based binder, the term "total cellulose-based agent content" describes the combined cellulose-based film former content, cellulose-based strengthening agent content, and cellulose-based binder content of the aerosol-forming substrate.

[0058] As used herein with reference to the present invention, the term "total carboxylic acid content" is used to describe the combined content of all carboxylic acids in an aerosol-forming substrate. For example, where the aerosol-forming substrate comprises a plurality of carboxylic acids consisting of benzoic acid and fumaric acid, the term "total carboxylic acid content" describes the combined benzoic acid content and fumaric acid content of the aerosol-forming substrate.

[0059] The aerosol-forming substrate may comprise water.

[0060] The aerosol-forming substrate may have a water content of between 5% and 35% by weight.

[0061] The aerosol-forming substrate may be a solid film.

[0062] As used herein with reference to the present invention, the term "film" is used to describe a solid aerosol-forming substrate having a thickness that is significantly less than its width or length.

[0063] As used herein with reference to the present invention, the term "thickness" is used to describe the smallest dimension between opposing substantially parallel surfaces of a solid aerosol-generating film.

[0064] According to yet another embodiment, an aerosol-generating article is provided, comprising an aerosol-forming substrate having a total aerosol-forming agent content of greater than or equal to 30% by weight, and wherein the aerosol-forming agent substrate is a solid or a gel; and an aerosol-generating device. The aerosol-generating device comprises: a heating chamber configured to at least partially receive the aerosol-generating article; a heating system associated with a heating element configured to internally heat the aerosol-forming substrate from within the aerosol-forming substrate; a power source for providing power to the heating system; and a controller configured to control the power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user to: increase the temperature of the heating element from an initial temperature to a first temperature; and maintain the temperature of the heating element constant at the first temperature for a duration of a first predetermined time period, wherein the first temperature is between 245 degrees Celsius and 285 degrees Celsius.

[0065] The first time period may have a duration of 40 seconds to 300 seconds, preferably 40 seconds to 150 seconds.

[0066] Controlling power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user may further comprise adjusting the temperature of the heating element to a second temperature during a second predetermined time period, wherein the second predetermined time period may be subsequent to the first predetermined time period.

[0067] The second predetermined time period may immediately follow the first predetermined time period.

[0068] The second temperature may be different from the first temperature.

[0069] The second temperature may be lower than the first temperature.

[0070] The second temperature may be between 190 degrees Celsius and 220 degrees Celsius.

[0071] Adjusting the temperature of the heating element to the second temperature during the second predetermined time period may include two consecutive temperature steps.

[0072] The temperature of the first temperature step may be lower than the temperature of the second temperature step.

[0073] Adjusting the temperature of the heating element to a second temperature during the second predetermined time period may include increasing the temperature of the heating element from a first temperature.

[0074] The duration of the second predetermined time period may be between 100 seconds and 280 seconds.

[0075] Controlling power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user may further comprise adjusting the temperature of the heating element to a third temperature during a third predetermined time period, wherein the third predetermined time period may be after the second predetermined time period.

[0076] The third temperature may substantially correspond to the first temperature.

[0077] The third predetermined time period may immediately follow the second predetermined time period.

[0078] The duration of the third predetermined time period may be between 30 seconds and 120 seconds.

[0079] The aerosol generating device may further include a memory configured to store a plurality of heating curves, wherein each heating curve may define how the temperature of the heating element is adjusted during each of the time periods, and wherein the controller may further be configured to control power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user based on a heating curve in the plurality of heating curves.

[0080] The controller may also be configured to select a heating profile based on identifying the aerosol-generating article.

[0081] The aerosol generating device may further include a memory configured to store a plurality of heating curves, wherein each heating curve may define how the temperature of the heating element is adjusted during a second predetermined time period, and wherein the controller may further be configured to control power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user based on a heating curve in the plurality of heating curves.

[0082] The controller may also be configured to select a heating profile based on identifying the aerosol-generating article.

[0083] The aerosol-forming substrate may further comprise a heating element, wherein the heating system may comprise an induction coil for inductively heating the heating element.

[0084] The controller may also be configured to control power to increase the temperature of the heating element from the ambient temperature to the initial temperature during a preheating period prior to the first predetermined period.

[0085] The preheat period may have a duration between 10 and 20 seconds.

[0086] The controller may also be configured to calibrate the heating element after the preheat period and before the first period.

[0087] The heating system may include a heating element that is a resistive heating element.

[0088] The controller may also be configured to control power to increase the temperature of the heating element from the ambient temperature to the initial temperature during a preheating period prior to the first predetermined period.

[0089] The preheat period may have a duration between 10 and 20 seconds.

[0090] The aerosol-forming substrate may comprise a total aerosol-former content of greater than 35% by weight.

[0091] The aerosol-forming substrate may comprise a total aerosol-former content of greater than 40% by weight.

[0092] The aerosol-forming substrate may comprise a total aerosol-former content of greater than 45% by weight.

[0093] The aerosol-forming substrate may comprise one or more aerosol formers selected from 1,3-butanediol, glycerol, 1,3-propanediol, propylene glycol, triethylene glycol, glycerol monoacetate, glycerol diacetate, glycerol triacetate, dimethyl dodecanedioate and dimethyl tetradecanedioate.

[0094] The aerosol-forming substrate may not comprise tobacco.

[0095] The aerosol-forming substrate may also comprise nicotine.

[0096] The aerosol-forming substrate may further comprise one or more cellulose-based agents and one or more carboxylic acids selected from fumaric acid, maleic acid and malic acid.

[0097] The aerosol-forming substrate may have a total cellulose-based agent content of at least 35 wt % and a total carboxylic acid content of at least 0.5 wt %.

[0098] The aerosol-forming substrate may comprise water.

[0099] The aerosol-forming substrate may have a water content of between 5% and 35% by weight.

[0100] As used herein, the terms "puff" and "inhalation" are used interchangeably and are intended to refer to the action of a user inhaling an aerosol into their body through their mouth or nose. Inhalation includes situations where the aerosol is inhaled into the user's lungs, and also includes situations where the aerosol is simply inhaled into the user's mouth or nasal cavity before being expelled from the user's body.

[0101] As used herein, "use process" refers to the use period of the device starting from the user starting the device. The use process may include a preheating phase, in which the aerosol generating device is configured to supply power to the heating system to heat the aerosol-forming substrate to generate an aerosol. The use process may include a calibration phase to calibrate the heating system so as to more accurately control the temperature of the heating element. The use process may include a main phase, during which the user can inhale the generated aerosol. The main phase can be long enough for multiple puffs. The main phase can be long enough for three, four, five or six puffs. The main phase can be long enough for more than six puffs. At the end of the use phase, the aerosol generating device can be configured to stop supplying power to the heating system. The aerosol-forming substrate can be removed from the aerosol generating device at the end of the use process. The aerosol-forming substrate can be replaced in a later use process. The duration of the use process between the start of the use process and the end of the use process can be at least one minute, two minutes, three minutes, four minutes, five minutes or six minutes. Preferably, the use process can have a duration of about four and a half minutes.

[0102] As used herein in reference to an aerosol generating device, the terms "upstream" and "front" and "downstream" and "rear" are used to describe the relative position of components or parts of components of an aerosol generating device relative to the direction in which air flows through the aerosol generating device during use. An aerosol generating device according to the present invention comprises a proximal end through which, in use, an aerosol leaves the device. The proximal end of the aerosol generating device may also be referred to as a mouth end or a downstream end. The mouth end is downstream of the distal end. The distal end of the aerosol generating article may also be referred to as an upstream end. Components or parts of components of an aerosol generating device may be described as being upstream or downstream of each other based on their relative position relative to the airflow path of the aerosol generating device.

[0103] As used herein in reference to aerosol-generating articles, the terms "upstream" and "front" and "downstream" and "rear" are used to describe the relative position of components or portions of components of an aerosol-generating article relative to the direction of air flowing through the aerosol-generating article during use. An aerosol-generating article according to the present invention comprises a proximal end through which, in use, the aerosol leaves the article. The proximal end of the aerosol-generating article may also be referred to as the mouth end or downstream end. The mouth end is downstream of the distal end. The distal end of the aerosol-generating article may also be referred to as the upstream end. Components or portions of components of an aerosol-generating article may be described as being upstream or downstream of each other based on their relative position between the proximal end of the aerosol-generating article and the distal end of the aerosol-generating article. The front portion of a component or portion of a component of an aerosol-generating article is the portion at the end closest to the upstream end of the aerosol-generating article. The rear portion of a component or portion of a component of an aerosol-generating article is the portion at the end closest to the downstream end of the aerosol-generating article.

[0104] As used herein, "aerosol-cooling element" refers to a component of an aerosol-generating article located downstream of an aerosol-forming substrate such that, in use, an aerosol formed by volatile compounds released from the aerosol-forming substrate passes through and is cooled by the aerosol-cooling element before being inhaled by a user. Aerosol-cooling elements have a large surface area but cause a low pressure drop. Filters and other mouthpieces that produce a high pressure drop (e.g., filters formed from fiber bundles) are not considered to be aerosol-cooling elements. Chambers and cavities within aerosol-generating articles are not considered to be aerosol-cooling elements.

[0105] As used herein, the term "mouthpiece" refers to the portion of an aerosol-generating article, an aerosol-generating device or an aerosol-generating system that is placed in the mouth of a user for direct inhalation of an aerosol.

[0106] As used herein with reference to the present invention, the term "mode" refers to the operating mode that the controller is programmed to perform. For example, in calibration mode, the controller is configured to perform a preprogrammed calibration process. In preheat mode, the controller is configured to perform a preprogrammed preheat process. In heating mode, the controller is configured to perform a heating process. The term "phase" may be used interchangeably with the term "mode" herein. The controller may be a microcontroller. The controller may include a microprocessor, such as a programmable microprocessor. The controller may include non-volatile memory. The aerosol generating device may include an interface configured to allow data to be transmitted from an external device to the controller and from the controller to the external device. The interface may allow software to be uploaded to the controller to run on the programmable microprocessor. The interface may be a wired interface, such as a micro USB port, or may be a wireless interface.

[0107] The invention is defined in the claims. However, a non-exhaustive list of non-limiting examples is provided below. Any one or more features of these examples may be combined with any one or more features of another example, embodiment or aspect described herein.

[0108] Example Ex1: A method for controlling aerosol generation in an aerosol generating device, the device comprising: a heating chamber, the heating chamber being configured to at least partially receive an aerosol generating article comprising an aerosol-forming substrate; a heating system, the heating system being associated with a heating element, the heating element being configured to heat the aerosol-forming substrate from within the aerosol-forming substrate; and a power source, the power source being used to provide power to the heating system; the method comprising: receiving the aerosol generating article by the heating chamber, wherein the aerosol-forming substrate has a total aerosol former content greater than 30 weight %, and wherein the aerosol-forming substrate is a solid or a gel; and heating the aerosol-forming substrate to form an aerosol for inhalation by a user by controlling the power to perform the following operations: increasing the temperature of the heating element from an initial temperature to a first temperature; and maintaining the temperature of the heating element constant at the first temperature for a duration of a first predetermined time period, wherein the first temperature is between 245 degrees Celsius and 285 degrees Celsius.

[0109] Example Ex2: The method according to example Ex1, wherein the first time period has a duration of 40 seconds to 300 seconds, preferably 40 seconds to 150 seconds.

[0110] Example Ex3: The method according to the preceding example, wherein controlling the power further comprises adjusting the temperature of the heating element to a second temperature during a second predetermined time period, wherein the second predetermined time period is after the first predetermined time period.

[0111] Example Ex4: The method according to example Ex3, wherein the second temperature is different from the first temperature.

[0112] Example Ex5: The method according to example Ex3 or Ex4, wherein the second temperature is lower than the first temperature.

[0113] Example Ex6: The method according to example Ex5, wherein the second temperature is between 190 degrees Celsius and 220 degrees Celsius.

[0114] Example Ex7: The method according to one of Examples Ex3 to Ex6, wherein adjusting the temperature of the heating element to the second temperature during the second time period comprises two consecutive temperature steps.

[0115] Example Ex8: The method according to example Ex7, wherein the temperature of the first temperature step is lower than the temperature of the second temperature step.

[0116] Example Ex9: The method of example Ex3 or Ex4, wherein adjusting the temperature of the heating element to a second temperature during the second predetermined time period includes increasing the temperature of the heating element from the first temperature.

[0117] Example Ex10: The method according to one of examples Ex3 to Ex9, wherein the duration of the second predetermined time period is between 100 seconds and 280 seconds.

[0118] Example Ex11: The method according to one of Examples Ex3 to Ex10, wherein controlling the power further comprises adjusting the temperature of the heating element to a third temperature during a third predetermined time period, wherein the third predetermined time period is after the second predetermined time period.

[0119] Example Ex12: The method according to example Ex11, wherein the third temperature substantially corresponds to the first temperature.

[0120] Example Ex13: The method according to example Ex11 or Ex12, wherein the duration of the third predetermined time period is between 30 seconds and 120 seconds.

[0121] Example Ex14: The method according to one of the examples Ex3 to Ex13, wherein the power is controlled based on a heating curve of a plurality of heating curves, wherein each heating curve defines how the temperature of the heating element is adjusted during each of the time periods.

[0122] Example Ex15: The method according to Example Ex14, further comprising selecting the heating curve based on identifying the aerosol-generating article.

[0123] Example Ex16: The method according to one of Examples Ex3 to Ex13, wherein the power is controlled based on a heating curve of a plurality of heating curves, wherein each heating curve defines how to adjust the temperature of the heating element during the second time period.

[0124] Example Ex17: The method according to Example Ex16, further comprising selecting the heating curve based on identifying the aerosol-generating article.

[0125] Example Ex18: The method according to one of the preceding examples, wherein the heating system comprises an induction coil configured to inductively heat the heating element.

[0126] Example Ex19: The method according to one of the preceding examples, wherein the method further comprises controlling the power to: increase the temperature of the heating element from the ambient temperature to the initial temperature during a preheating period before the first predetermined period.

[0127] Example Ex20: The method according to example Ex19, wherein the preheating period has a duration between 10 seconds and 20 seconds.

[0128] Example Ex21: The method according to one of Examples Ex19 or Ex20, further comprising calibrating the heating element after the preheating period and before the first predetermined period.

[0129] Example Ex22: The method according to one of Examples Ex1 to Ex17, wherein the heating system comprises the heating element, and the heating element is a resistive heating element.

[0130] Example Ex23: The method according to Example Ex22, wherein the method further comprises controlling the power to: increase the temperature of the heating element from the ambient temperature to the initial temperature during a preheating period before the first predetermined period.

[0131] Example Ex24: The method according to example Ex23, wherein the preheating period has a duration between 10 seconds and 20 seconds.

[0132] Example Ex25: The method according to one of the preceding examples, wherein the aerosol-forming substrate comprises a total aerosol-former content of greater than 35% by weight.

[0133] Example Ex26: The method according to one of the preceding examples, wherein the aerosol-forming substrate comprises a total aerosol-former content of greater than 40% by weight.

[0134] Example Ex27: The method according to one of the preceding examples, wherein the aerosol-forming substrate comprises a total aerosol-former content of greater than 45% by weight.

[0135] Example Ex28: A method according to one of the preceding examples, wherein the aerosol-forming substrate comprises one or more aerosol formers selected from 1,3-butanediol, glycerol, 1,3-propylene glycol, propylene glycol, triethylene glycol, glyceryl monoacetate, glyceryl diacetate, glyceryl triacetate, dimethyl dodecanedioate and dimethyl tetradecanedioate.

[0136] Example Ex29: A method according to one of the preceding examples, wherein the aerosol-forming substrate does not comprise tobacco.

[0137] Example Ex30: The method according to one of the preceding examples, wherein the aerosol-forming substrate further comprises nicotine.

[0138] Example Ex31: The method according to one of the preceding examples, wherein the aerosol-forming substrate further comprises one or more cellulose-based agents and one or more carboxylic acids selected from fumaric acid, maleic acid and malic acid.

[0139] Example Ex32. A method according to example Ex31, wherein the aerosol-forming substrate has a total cellulose-based agent content of at least 35 wt.-% and a total carboxylic acid content of at least 0.5 wt.-%.

[0140] Example Ex33: A method according to one of the preceding examples, wherein the aerosol-forming substrate comprises water.

[0141] Example Ex34: A method according to example Ex33, wherein the aerosol-forming substrate has a water content of between 5% and 35% by weight.

[0142] Example Ex35: A system comprising: an aerosol-generating article, the aerosol-generating article comprising an aerosol-forming substrate, the aerosol-forming substrate having a total aerosol-forming agent content greater than or equal to 30 weight percent, and wherein the aerosol-forming agent substrate is a solid or a gel; and an aerosol-generating device, the aerosol-generating device comprising: a heating chamber, the heating chamber being configured to at least partially receive the aerosol-generating article; a heating system, the heating system being associated with a heating element, the heating element being configured to heat the aerosol-forming substrate from within the aerosol-forming substrate; a power source, the power source being used to provide power to the heating system; and a controller, the controller being configured to control the power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user to: increase the temperature of the heating element from an initial temperature to a first temperature; and maintain the temperature of the heating element constant at the first temperature for a duration of a first predetermined time period, wherein the first temperature is between 245 degrees Celsius and 285 degrees Celsius.

[0143] Example Ex36: A system according to example Ex35, wherein the first time period has a duration of 40 seconds to 300 seconds, preferably 40 seconds to 150 seconds.

[0144] Example Ex37: A system according to Example Ex35 or Ex36, wherein controlling the power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user also includes adjusting the temperature of the heating element to a second temperature during a second predetermined time period, wherein the second predetermined time period is after the first predetermined time period.

[0145] Example Ex38: The system of example Ex37, wherein the second temperature is different from the first temperature.

[0146] Example Ex39: A system according to example Ex36 or Ex37, wherein the second temperature is lower than the first temperature.

[0147] Example Ex40: The system of example Ex39, wherein the second temperature is between 190 degrees Celsius and 220 degrees Celsius.

[0148] Example Ex41: The system of one of Examples Ex37 to Ex39, wherein adjusting the temperature of the heating element to the second temperature during the second predetermined time period comprises two consecutive temperature steps.

[0149] Example Ex42: The system according to example Ex41, wherein the temperature of the first temperature step is lower than the temperature of the second temperature step.

[0150] Example Ex43: The system of example Ex37 or Ex38, wherein adjusting the temperature of the heating element to a second temperature during the second predetermined time period comprises increasing the temperature of the heating element from the first temperature.

[0151] Example Ex44: A system according to one of examples Ex37 to Ex43, wherein the duration of the second predetermined time period is between 100 seconds and 280 seconds.

[0152] Example Ex45: A system according to one of Examples Ex37 to Ex40, wherein controlling the power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user also includes adjusting the temperature of the heating element to a third temperature during a third predetermined time period, wherein the third predetermined time period is after the second predetermined time period.

[0153] Example Ex46: The system of example Ex45, wherein the third temperature substantially corresponds to the first temperature.

[0154] Example Ex47: A system according to example Ex45 or Ex46, wherein the duration of the third predetermined time period is between 30 seconds and 120 seconds.

[0155] Example Ex48: A system according to one of Examples Ex37 to Ex47, wherein the aerosol generating device further comprises a memory configured to store a plurality of temperature curves, wherein each heating curve defines how to adjust the temperature of the heating element during each of the time periods, and wherein the controller is further configured to control the power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user based on a heating curve of the plurality of temperature curves.

[0156] Example Ex49: The system of Example Ex48, wherein the controller is further configured to select the heating profile based on identifying the aerosol-generating article.

[0157] Example Ex50: A system according to one of Examples Ex37 to Ex47, wherein the aerosol generating device further comprises a memory configured to store a plurality of temperature curves, wherein each heating curve defines how to adjust the temperature of the heating element during the second predetermined time period, and wherein the controller is further configured to control the power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user based on a heating curve of the plurality of temperature curves.

[0158] Example Ex51: The system according to example Ex50, wherein the controller is further configured to select the heating profile based on identifying the aerosol-generating article.

[0159] Example Ex52: A system according to one of Examples Ex35 to Ex51, wherein the aerosol-forming substrate further comprises the heating element, and wherein the heating system comprises an induction coil for inductively heating the heating element.

[0160] Example Ex53: The system according to one of Examples Ex35 to Ex52, wherein the controller is further configured to: during a preheating period before the first predetermined period, control the power to increase the temperature of the heating element from the ambient temperature to the initial temperature.

[0161] Example Ex54: The system of example Ex52 or Ex53, wherein the preheating period has a duration between 10 seconds and 20 seconds.

[0162] Example Ex55: The system of one of Examples Ex52 to Ex54, wherein the controller is further configured to calibrate the heating element after the preheating time period and before the first time period.

[0163] Example Ex56: A system according to one of Examples Ex35 to Ex51, wherein the heating system comprises the heating element, and the heating element is a resistive heating element.

[0164] Example Ex57: The system of Example Ex56, wherein the controller is further configured to: during a preheating period prior to the first predetermined period, control the power to increase the temperature of the heating element from the ambient temperature to the initial temperature.

[0165] Example Ex58: The system of example Ex57, wherein the preheating period has a duration between 10 seconds and 20 seconds.

[0166] Example Ex59: A method according to one of Examples Ex35 to Ex58, wherein the aerosol-forming substrate comprises a total aerosol-former content of greater than 35% by weight.

[0167] Example Ex60: The method according to one of Examples Ex35 to Ex59, wherein the aerosol-forming substrate comprises a total aerosol former content of greater than 40% by weight.

[0168] Example Ex61: A method according to one of Examples Ex35 to Ex60, wherein the aerosol-forming substrate comprises a total aerosol-former content of greater than 45% by weight.

[0169] Example Ex62: A system according to one of Examples Ex35 to Ex61, wherein the aerosol-forming substrate comprises one or more aerosol formers selected from 1,3-butanediol, glycerol, 1,3-propylene glycol, propylene glycol, triethylene glycol, glyceryl monoacetate, glyceryl diacetate, glyceryl triacetate, dimethyl dodecanedioate and dimethyl tetradecanedioate.

[0170] Example Ex63: A system according to one of examples Ex35 to Ex62, wherein the aerosol-forming substrate does not include tobacco.

[0171] Example Ex64: A system according to one of examples Ex35 to Ex63, wherein the aerosol-forming substrate further comprises nicotine.

[0172] Example Ex65: A system according to one of examples Ex35 to Ex64, wherein the aerosol-forming substrate further comprises one or more cellulose-based agents and one or more carboxylic acids selected from fumaric acid, maleic acid and malic acid.

[0173] Example Ex66: A system according to example Ex65, wherein the aerosol-forming substrate has a total cellulose-based agent content of at least 35 wt.-% and a total carboxylic acid content of at least 0.5 wt.-%.

[0174] Example Ex67: A system according to one of Examples Ex35 to Ex66, wherein the aerosol-forming substrate comprises water.

[0175] Example Ex68: A system according to example Ex67, wherein the aerosol-forming substrate has a water content of between 5 wt % and 35 wt %.

[0176] Several examples will now be further described with reference to the accompanying drawings, in which:

[0177] Figure 1 is a schematic cross-sectional view of an aerosol-generating article comprising an aerosol-forming substrate and a susceptor;

[0178] Figure 2 Yes Figure 1 Schematic cross-sectional view of an aerosol generating article and an aerosol generating system of an electrically operated aerosol generating device including an inductor;

[0179] Figure 3 is a graph of DC current versus time illustrating a remotely detectable current change that occurs when a susceptor material undergoes a phase change associated with its Curie point;

[0180] Figure 4 is a graph of conductance versus time illustrating changes in conductance corresponding to changes in temperature of a susceptor during user operation of an aerosol generating device;

[0181] Figure 5 shows a schematic cross-sectional view of an aerosol-generating article comprising an aerosol-forming substrate;

[0182] Figure 6 Shown include Figure 5 Schematic cross-sectional view of an aerosol-generating article and an aerosol-generating system of an electrically operated aerosol-generating device comprising a resistive heater for internally heating the aerosol-forming substrate from within the aerosol-forming substrate;

[0183] Figure 7 It is explained in Figure 6 a graph of temperature versus time for a portion of a heating curve during user operation of an aerosol generating device as shown in;

[0184] Figure 8 It is explained in Figure 2 or a graph of temperature versus time for a portion of a heating curve during user operation of the aerosol generating device shown in 6;

[0185] Fig. 9 It is explained in Figure 2 or a graph of temperature versus time for a portion of a heating curve during user operation of the aerosol generating device shown in 6;

[0186] Fig.10 It is explained in Figure 2 or a graph of temperature versus time for a portion of a heating curve during user operation of the aerosol generating device shown in 6;

[0187] Fig.11 It is explained in Figure 2 or a graph of temperature versus time for a portion of a heating curve during user operation of the aerosol generating device shown in 6;

[0188] Fig.12 It is explained in Figure 2or a graph of temperature versus time for a portion of a heating curve during user operation of the aerosol generating device shown in 6;

[0189] Fig.13 It is explained in Figure 2 or a graph of temperature versus time for a portion of a heating curve during user operation of the aerosol generating device shown in 6; and

[0190] Fig.14 is a flow chart of a method of controlling aerosol generation in an aerosol generating device.

[0191] Figure 1 is a schematic cross-sectional view of an aerosol-generating article 10 in which an aerosol-forming substrate of the aerosol-generating article is inductively heated from the inside; and

[0192] Figure 2 Yes Figure 1 Schematic cross-sectional view of an aerosol generating system 100 of an aerosol generating article 10 and an electrically operated aerosol generating device 110 comprising an inductor is shown in FIG.

[0193] Figure 1 The aerosol-generating article 10 shown in FIG. 1 comprises an aerosol-generating strip 12, a proximal section 14 located downstream of the aerosol-generating strip 12, and a distal section 16 located upstream of the aerosol-generating strip 12. Figure 1 As shown in , the aerosol-generating article 10 has an upstream or distal end 18 and a downstream or proximal end 20.

[0194] The proximal section 14 of the aerosol-generating article 10 comprises a support element 22 positioned immediately downstream of the aerosol-generating strip 12 , an aerosol-cooling element 24 positioned immediately downstream of the support element 22 , and a mouthpiece element 42 positioned immediately downstream of the aerosol-cooling element 24 .

[0195] The support element 22 comprises a first hollow tubular segment 26. The first hollow tubular segment 26 is in the form of a hollow cylindrical tube made of cellulose acetate. The first hollow tubular segment 26 defines an inner cavity 28 extending from an upstream end 30 of the first hollow tubular segment to a downstream end 32 of the first hollow tubular segment 20.

[0196] The aerosol-cooling element 24 comprises a second hollow tubular segment 34. The second hollow tubular segment 34 is in the form of a hollow cylindrical tube made of cellulose acetate. The second hollow tubular segment 34 defines an inner cavity 36 extending from an upstream end 38 of the second hollow tubular segment to a downstream end 40 of the second hollow tubular segment 34.

[0197] like Figure 1 As shown by the vertical dashed lines in , the aerosol-generating article 10 includes a ventilation zone 60 disposed at a location along the second hollow tubular segment 34 .

[0198] The mouthend element 42 is in the form of a cylindrical low density cellulose acetate rod.

[0199] Aerosol generating strip 12 comprises an aerosol forming substrate. The aerosol forming substrate can be a solid or a gel. The aerosol forming substrate comprises one or more aerosol forming agents such as glycerol or propylene glycol. The total aerosol forming agent content of the aerosol forming substrate can be greater than 30 weight %. The total aerosol forming agent content of the aerosol forming substrate can be greater than 40 weight %. The total aerosol forming agent content of the aerosol forming substrate can be greater than 45 weight %. The aerosol forming substrate can be a non-tobacco substrate that does not include tobacco-containing material. Alternatively, the aerosol forming substrate can include tobacco-containing material. In addition, the aerosol forming substrate can include water. The aerosol forming substrate can have a water content between 5 weight % and 35 weight %.

[0200] The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise one or more cellulose-based agents. The aerosol-forming substrate may comprise one or more carboxylic acids. The one or more carboxylic acids may be selected from fumaric acid, maleic acid and malic acid.

[0201] The aerosol-forming substrate may be an aerosol-generating film and the aerosol-generating strip 12 may comprise a gathered crimped paper sheet coated with a solid aerosol-generating film.

[0202] The aerosol-generating article 10 includes a heating element, such as a susceptor 44, located within the aerosol-generating rod 12. Figure 2 As shown in FIG. 4 , the susceptor 44 is surrounded by the aerosol-forming substrate and extends along the longitudinal axis of the aerosol-generating rod 12 from the upstream end of the aerosol-generating rod 12 to the downstream end of the aerosol-generating rod 12. The susceptor 44 is in direct contact with the aerosol-forming substrate.

[0203] The susceptor 44 may be in the form of a strip having a length of 12 millimeters, a width of 5 millimeters, and a thickness of 60 micrometers. The susceptor 44 comprises at least two different materials. The susceptor 44 comprises at least two layers: a first layer of a first susceptor material disposed in physical contact with a second layer of a second susceptor material. The first susceptor material and the second susceptor material may each have a Curie temperature. In this case, the Curie temperature of the second susceptor material is lower than the Curie temperature of the first susceptor material. The first material may not have a Curie temperature. The first susceptor material may be aluminum, iron, or stainless steel. The second susceptor material may be nickel or a nickel alloy.

[0204] The distal section 16 of the aerosol-generating article 10 comprises an upstream element 46 positioned immediately upstream of the aerosol-generating rod 12 .

[0205] The upstream element 46 is in the form of a cylindrical cellulose acetate rod defined by a rigid wrapper.

[0206] Figure 2 The aerosol generating system 100 shown in FIG. Figure 1 An aerosol-generating article 10 and a handheld electrically-operated aerosol-generating device 110 are shown in FIG.

[0207] The aerosol-generating device 110 comprises a housing 112 defining a heating chamber 114 configured to receive a distal portion of the aerosol-generating article 10 .

[0208] The aerosol generating device 110 includes a power source (not shown) and a heating system (not shown). The heating system includes a controller, a DC / AC converter and an inductor 116. The power source may be a battery, such as a rechargeable lithium-ion battery. The inductor 116 includes an induction coil. The controller controls the supply of power from the power source to the induction coil.

[0209] In use, the fluctuating or alternating electromagnetic field generated by the induction coil of the inductor 116 induces eddy currents in the susceptor 44 in the aerosol-generating strip 12 of the aerosol-generating article 10, thereby heating the susceptor 44. The heat generated in the susceptor 44 is transferred to the aerosol-forming substrate in the aerosol-generating strip 12 of the aerosol-generating article 10 by conduction.

[0210] The user draws on the mouthpiece element 42 of the aerosol generating article 10. As the user draws on the mouthpiece element 42, air is drawn into the aerosol generating article 10 through the distal end 18. The drawn air passes through the upstream element 46 to the aerosol generating strip 12. The heating of the aerosol-forming substrate releases volatile compounds and semi-volatile compounds, which form aerosols entrained in the drawn air as the drawn air flows through the aerosol generating strip 12. The drawn air and the entrained aerosol pass through the middle hollow section 50 of the aerosol generating article 10, where they cool and condense. The cooled aerosol then passes through the mouthpiece element 42 of the aerosol generating article 10 to the user's mouth.

[0211] Figure 3 4 shows the relationship between the DC current IDC drawn from the power supply and time as the temperature of the susceptor 44 (indicated by the dashed line) increases. More specifically, Figure 3 The remotely detectable DC current change that occurs when the susceptor material undergoes a phase change associated with its Curie point is shown. The DC current IDC drawn from the power supply is measured at the input side of the DC / AC converter. For the purposes of this illustration, it can be assumed that the voltage VDC of the power supply remains approximately constant.

[0212] As the susceptor 44 is inductively heated, the apparent resistance of the susceptor 44 increases. This increase in resistance is observed as a decrease in the DC current IDC drawn from the power supply, which decreases as the temperature of the susceptor 44 increases at a constant voltage. The high frequency alternating magnetic field provided by the inductor induces eddy currents in close proximity to the susceptor surface, an effect known as the skin effect. The resistance in the susceptor 44 depends in part on the resistivity of the first susceptor material, the resistivity of the second susceptor material, and in part on the depth of the skin layer in each material available for induced eddy currents, and the resistivity in turn is temperature dependent.

[0213] When the second susceptor material reaches its Curie temperature it loses its magnetic properties. This causes an increase in the skin layer available for eddy currents in the second susceptor material, which causes a decrease in the apparent resistance of the susceptor 44. The result is a temporary increase in the detected DC current IDC. Then, when the skin depth of the second susceptor material begins to increase, the resistance begins to decrease. This Figure 3 The middle is regarded as a valley (local minimum) 310.

[0214] As heating continues, the current continues to increase until the maximum skin depth is reached, which coincides with the point at which the second susceptor material has lost its spontaneous magnetic properties. This point is called the Curie temperature and is Figure 3 320. At this point, the second susceptor material has undergone a phase transition from a ferromagnetic or ferrimagnetic state to a paramagnetic state. At this point, the susceptor 160 is at a known temperature (the Curie temperature, which is an intrinsic material-specific temperature).

[0215] If inductive heating of the susceptor 44 continues after the Curie temperature has been reached, the eddy currents generated in the susceptor 44 will act against the resistance of the susceptor 44, whereby Joule heating in the susceptor 44 will continue, and whereby the resistance will increase again (the resistance will have a polynomial dependence on temperature, which for most metallic susceptor materials can be approximated to a cubic polynomial dependence for our purposes), and the current will begin to decrease again.

[0216] Therefore, the second susceptor material is heated by Figure 3 The (known) temperature range between the valley 310 and the hill 320 shown in FIG. Figure 3It can be seen that the apparent resistance of the susceptor 44 and thus the start and end of the reversible phase change can be remotely detected by monitoring at least the DC current IDC drawn from the power supply. Although the DC supply voltage VDC is known, the DC supply voltage VDC can also be monitored in addition to the DC current IDC. Therefore, the apparent resistance of the susceptor 44 and thus the start and end of the phase change can be remotely detected by monitoring the conductance value (where the conductance is defined as the ratio of the DC current IDC to the DC supply voltage VDC) or the resistance value (where the resistance is defined as the ratio of the DC supply voltage VDC to the DC current IDC). The DC current IDC, the conductance value and the resistance value can be referred to as power supply parameters.

[0217] As from Figure 3 It can be seen that between the start and end of the reversible phase change, in other words, between the valley 310 and the hill 320, the apparent resistance of the susceptor 44 (and accordingly the current IDC drawn from the power supply) can vary with the temperature of the susceptor 44 in a strictly monotonic relationship. The strictly monotonic relationship allows the temperature of the susceptor 44 to be determined unambiguously from determining the apparent resistance (R) or the apparent conductance (1 / R). This is because each determined value of the apparent resistance represents only one single value of the temperature, so that there is no ambiguity in the relationship. The monotonic relationship of the temperature and apparent resistance of the susceptor 44 over the temperature range over which the second susceptor material undergoes a reversible phase change allows the temperature of the susceptor 44, and therefore the temperature of the aerosol-forming substrate, to be determined and controlled.

[0218] The controller adjusts the power supply provided to the heating system based on the measured value of the power supply parameter. The heating system may include a current sensor (not shown) to measure the DC current IDC. The heating system may optionally include a voltage sensor (not shown) to measure the DC supply voltage VDC. The current sensor and the voltage sensor are located at the input side of the DC / AC converter. The DC current IDC and the optional DC supply voltage VDC are provided to the controller by a feedback channel to control the further supply of AC power PAC to the inductor 116.

[0219] The controller may control the temperature of susceptor 44 by maintaining the measured power parameter value at a target value corresponding to a target operating temperature of susceptor 44. In other words, the controller adjusts the temperature of susceptor 44 by controlling the power provided to the heating system to adjust the power parameter value.

[0220] In order to take advantage of the strictly monotonic relationship between the apparent resistance (or apparent conductance) of the susceptor 44 and the temperature of the susceptor 44, during user operation for generating aerosols, the power supply parameter measured at the input side of the DC / AC converter is maintained between a first calibration value corresponding to the first calibration temperature and a second calibration value corresponding to the second calibration temperature. The second calibration temperature is the Curie temperature ( Figure 3The first calibration temperature is greater than when the skin depth of the second susceptor material begins to increase (causing a temporary decrease in resistance) ( Figure 3 The first calibration temperature is a temperature greater than or equal to the temperature of the susceptor material at the valley 310 in the current graph of the second susceptor. Thus, the first calibration temperature is a temperature greater than or equal to the temperature at the maximum magnetic permeability of the second susceptor material. The first calibration temperature is at least 50 degrees Celsius lower than the second calibration temperature. At least the second calibration value is determined by calibration of the susceptor 44, as will be described in more detail below. The first calibration value and the second calibration value may be stored as calibration values ​​in a memory of the aerosol generating device 110.

[0221] Since the power supply parameters will have a polynomial dependence on temperature, the power supply parameters will vary in a nonlinear manner according to temperature. However, the first calibration value and the second calibration value are selected so that this dependence can be approximated by a linear relationship between the first calibration value and the second calibration value because the difference between the first calibration value and the second calibration value is small and the first calibration value and the second calibration value are in the upper part of the operating temperature range. Therefore, in order to adjust the temperature to the target operating temperature, the power supply parameters are adjusted by a linear equation according to the first calibration value and the second calibration value.

[0222] For example, if the first calibration value and the second calibration value are conductance values, the target conductance value G corresponding to the target operating temperature R It can be given by the following equation:

[0223] GRGLower+(x×4G)

[0224] Where ΔG is the difference between the first conductance value and the second conductance value, and x is a percentage of ΔG. Thus, the controller adjusts the power parameter value based on the difference between the power parameter value measured at valley 310 during calibration and the power parameter value measured at hill 320 and valley 310 during calibration.

[0225] The first calibration value and the second calibration value are obtained by performing a calibration process. The controller is programmed to perform the calibration process each time the user operates the aerosol generating device 110. For example, the controller may be configured to enter a calibration mode for performing the calibration process when the user turns on the aerosol generating device 110. The controller may be programmed to enter the calibration mode each time the user inserts the aerosol generating article 10 into the aerosol generating device 110. Thus, the calibration process is performed during the first heating stage of the aerosol generating device before the main stage of the user inhaling the generated aerosol.

[0226] During the calibration process, the controller controls the DC / AC converter to continuously or continually supply power to the inductor 116 in order to heat the susceptor 44. The controller monitors the power supply parameter by measuring the current IDC drawn by the power supply and the optional power supply voltage VDC. When heating the susceptor 44, the measured current decreases until a valley (first turning point) 310 is reached and the current IDC begins to increase. This first turning point 310 corresponds to a local minimum conductance or current value (local maximum resistance value). The controller can record the power supply parameter value at the first turning point 310 as a first calibration value.

[0227] The temperature of the susceptor 44 at the first calibration value is the first calibration temperature. As the controller continues to control the power provided to the inductor 116 by the DC / AC converter, the controller continues to monitor the power parameter until a hill (second turning point) 320 is reached. The second turning point corresponds to the maximum current (corresponding to the Curie temperature of the second susceptor material) before the measured current begins to decrease. This second turning point 320 corresponds to a local maximum conductance or current value (local minimum resistance value). The control circuit system records the value of the power parameter at the second turning point 320 as the second calibration value. The temperature of the susceptor 44 at the second calibration value is the second calibration temperature. When the second turning point 320 is detected, the controller controls the DC / AC converter to interrupt the power supply to the inductor 116, thereby causing the temperature of the susceptor 44 to decrease and the measured current to decrease accordingly.

[0228] This process of continuously heating the susceptor 44 to obtain the first calibration value and the second calibration value may be repeated at least once during the calibration mode due to the shape of the graph 300. Preferably, the controller adjusts the power based on the power supply parameter value obtained from the minimum repetition of the calibration process, which is more reliable because the heat will have more time to disperse within the aerosol-forming substrate and the susceptor 44.

[0229] The controller is configured to detect turning points 310 and 320 by measuring a sequence of power supply parameter values. Figure 3 , the sequence of measured power supply parameter values ​​will form a curve in which each value is greater or less than the previous value. The controller is configured to measure the calibration value at the point where the curve begins to flatten out. In other words, the controller records the calibration value when the difference between consecutive power supply parameter values ​​is below a predetermined threshold.

[0230] To further improve the reliability of the calibration process, the controller may optionally be programmed to perform a preheating process prior to the calibration process. For example, if the aerosol-forming substrate is particularly dry or under similar conditions, the calibration process may be performed before the heat has diffused within the aerosol-forming substrate, thereby reducing the reliability of the calibration values. If the aerosol-forming substrate is humid, the susceptor 44 takes more time to reach the valley temperature (due to the water content in the aerosol-forming substrate).

[0231] To perform the preheating process, the controller is configured to continuously provide power to the inductor 116. Figure 3 As described, the measured current begins to decrease as the temperature of the susceptor 44 increases until a turning point 310 corresponding to the minimum measured current (conductance) is reached. At this stage, the controller is configured to wait for a predetermined period of time to allow the susceptor 44 to cool before continuing to heat. Therefore, the controller controls the DC / AC converter to interrupt the power supply to the sensor 116. After the predetermined period of time, the controller controls the DC / AC converter to provide power until the turning point 310 corresponding to the minimum measured current is reached again. At this time, the controller controls the DC / AC converter to interrupt the power supply to the sensor 116 again. The controller waits for the same predetermined period of time again to allow the susceptor 44 to cool before continuing to heat. This heating and cooling of the susceptor 44 is repeated within the predetermined duration of the preheating process 410. The predetermined duration of the preheating process is between 10 seconds and 20 seconds, preferably 11 seconds. The duration of the calibration process is between 10 seconds and 20 seconds. If the aerosol-forming substrate is dry, the first current minimum of the preheating process is reached within the predetermined period of time, and the power will be repeatedly interrupted until the predetermined period of time ends. If the aerosol-forming substrate has a high moisture content, the first current minimum value of the preheating process 410 will be reached towards the end of the predetermined time period. Thus, performing the preheating process for a predetermined duration ensures that, regardless of the physical condition of the aerosol-forming substrate, this time is sufficient for the aerosol-forming substrate to reach the minimum operating temperature in order to be ready for continuous current feeding and to reach the first maximum value. This allows calibration to be performed as early as possible, but still without running the risk that the aerosol-forming substrate will not have reached the first calibration temperature beforehand.

[0232] In particular, an aerosol-forming substrate comprising a higher aerosol-forming agent content (eg greater than 30 wt%) and a higher water content (eg greater than 5 wt%) will have a higher thermal inertia.Thus, the preheating process ensures that the minimum operating temperature is reached before calibration.

[0233] The preheating process may be performed in response to receiving a user input (e.g., a user activating the aerosol generating device 110). Additionally or alternatively, the control circuit system may be configured to detect the presence of an aerosol generating article 10 in the aerosol generating device 110, and the preheating process may be performed in response to detecting the presence of the aerosol generating article 10 within the heating chamber of the aerosol generating device 110.

[0234] Figure 44 is a graph of conductance versus time showing a heating curve for susceptor 44. The graph shows five phases of the heating curve: a preheating process performed during a preheating mode 410, a calibration process performed during a calibration mode 420, and a main phase of a user inhaling an aerosol including heating modes 430, 440, and 450. Although Figure 4 It is shown as a graph of conductance versus time, but it will be appreciated that the controller may be configured to control the heating of the susceptor 44 during each stage of the heating curve based on any measured power supply parameter, such as resistance or current as described above.

[0235] Once the calibration process 420 is completed, the controller is configured to interrupt the power provided to the heating system to allow the susceptor to cool to the initial temperature. Once the susceptor temperature is detected to be at the initial temperature, or after the susceptor temperature has been at the initial temperature for a predetermined period of time, the controller is configured to control the power provided to the heating system to increase the temperature of the susceptor 44 from the initial temperature to the first temperature. Specifically, the controller controls the power provided to the heating system to adjust the conductance to correspond to the first operating temperature of the susceptor 44 within the first predetermined period of time. In an example, the conductance during the first heating mode 430 is 0.75xΔG, in other words, 75% of the difference in conductance measured between the hills 320 and the valleys 310.

[0236] The first operating temperature is selected so that the desired volatile compounds are evaporated from the substrate, but undesirable compounds that evaporate or are generated at higher temperatures are not released. In addition, heating the susceptor 44 to the maximum operating temperature of the susceptor 44 immediately after the calibration process 420 improves the amount of the desired volatile compounds evaporated, thereby providing improved delivery to the user from the first puff. The first operating temperature of the susceptor 44 can be the maximum operating temperature of the susceptor 44.

[0237] Figure 5 is a schematic cross-sectional view of an aerosol-generating article 500; and

[0238] Figure 6 is a schematic cross-sectional view of an aerosol generating system 600, the aerosol generating system comprising Figure 5 An aerosol-generating article 500 and an electrically-operated aerosol-generating device 610 , the electrically-operated aerosol-generating device comprising a resistive heater configured to heat the aerosol-generating article 500 from within the aerosol-generating article 500 .

[0239] The aerosol generating article 500 has the same Figure 1 The aerosol-generating article 10 is described as being of substantially the same structure, with like elements being indicated by like reference numerals. However, it should be noted that the aerosol-generating article 500 does not include the susceptor 44. Additionally, the aerosol-generating article does not include the upstream element 46.

[0240] The aerosol generating device 610 includes a heating chamber 630 for receiving the aerosol generating article 500. The heating element 620 is located in the heating chamber and is positioned to engage with the distal end 18 of the aerosol generating article 500. The heating element 620 is a resistive heating element shaped as a blade terminating at a point. The heating element 620 can be formed by a ceramic substrate having one or more resistive heating traces, formed by platinum or another suitable material deposited on one or both sides of the blade. Alternatively, the heating element 620 can be one or more heating needles or rods that run through the center of the aerosol forming substrate 510. Other alternatives include heating wires or filaments, for example, Ni-Cr (nickel-chromium), platinum, tungsten or alloy wires or heating plates. Optionally, the heating element 620 can be deposited in or on a rigid carrier material. For example, the resistive heating element 620 can be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal can be formed as a trace on a suitable insulating material (such as a ceramic material) and then coated by another insulating material (such as glass). A heater formed in this manner may be used to both heat and monitor the temperature of the heating element during operation.

[0241] When the aerosol-generating article 500 is pushed onto the point of the heating element 620, the heating element 620 penetrates into the aerosol-forming substrate of the aerosol-generating rod 12 by applying force to the aerosol-generating article 500. Further penetration is prevented when the distal end 18 of the aerosol-generating article 500 abuts the end wall 640 of the heating chamber 630, which acts as a stop.

[0242] The heating element 620 is located within and in contact with the aerosol-forming substrate when the aerosol-generating article 500 is properly engaged with the aerosol-generating device 610. The heating element 620 heats the aerosol-forming substrate by means of conduction.

[0243] The aerosol generating device 610 includes a power source (not shown) and a heating system (not shown) electrically coupled to the power source. The heating system includes a controller and a heating element 620. The power source may be a battery, such as a rechargeable lithium-ion battery. The power source is configured to supply power to the heating system so as to heat the heating element 620.

[0244] The controller obtains a temperature indication of the heating element 620 (e.g., the resistance of the heating element) by measuring the resistance of the heating element 620. The temperature indication is used to adjust the current supplied to the heating element 620 so as to maintain the heating element 620 close to the target temperature. In other words, the controller adjusts the temperature of the heating element by adjusting the current supplied to the heating element 620.

[0245] This scheme relies on three or more temperature calibration points at which the resistance of the heating element 620 is measured. For temperatures intermediate the calibration points, the resistance values ​​are interpolated from the values ​​at the calibration points. The calibration point temperatures are selected to cover the expected temperature range of the heating element 620 during operation. Calibrating the heating element 620 to obtain the calibration points can be performed at the time of manufacture, and the calibration points are stored in the memory of the controller.

[0246] When the heating element 620 is heated, the aerosol-forming substrate is heated and volatile substances are formed. When a user draws on the proximal end 20 of the aerosol-generating article 500, air is drawn into the aerosol-generating article 500 and the volatile substances condense to form an inhalable aerosol. This aerosol passes through the proximal end 20 of the aerosol-generating article 500 and enters the user's mouth.

[0247] Figure 7 is a graph of heating element temperature versus time, showing the use of the above Figure 6 1 and 2. The heating element is at an initial temperature during stage 710. Stage 710 may be a preheating stage in which the controller is programmed to preheat the heating element to a predetermined initial temperature within a predetermined duration.

[0248] The preheating phase ensures that, regardless of the physical condition of the aerosol-forming substrate (e.g. dry or wet), the duration of the preheating phase is sufficient for the aerosol-forming substrate to reach the minimum operating temperature so as to be ready for continuous power supply and to reach the first operating temperature as quickly as possible for generating sufficient aerosol to be inhaled by the user.

[0249] In particular, an aerosol-forming substrate comprising a non-tobacco material will have a higher thermal inertia than a tobacco-based aerosol-forming substrate, because the non-tobacco aerosol-forming substrate comprises a higher aerosol-forming agent content (e.g., greater than 30% by weight) and a higher water content (e.g., greater than 5% by weight). Therefore, in the case of a non-tobacco aerosol-forming substrate with a higher moisture content, the preheating process ensures that the minimum operating temperature is reached before the main stage. The duration of the preheating mode is between 10 and 20 seconds, preferably 11 seconds.

[0250] After the preheating phase, the controller is configured to enter a first heating mode 720 of the main phase. The first heating mode may be entered in response to a timer indicating that a predetermined duration of the preheating phase 710 has elapsed, a user actuating the aerosol generating device, or after a user puff is detected. During the first heating mode 720, the controller rapidly increases the temperature of the heating element from an initial temperature to a first temperature.

[0251] The first temperature is selected so that the desired volatile compounds are evaporated from the substrate, but undesirable compounds that evaporate or are generated at higher temperatures are not released. In addition, rapidly heating the heating element to the first temperature of the heating element improves the amount of the desired volatile compounds evaporated, thereby providing improved delivery to the user from the first puff. The first temperature may be the maximum operating temperature of the heating element.

[0252] During stages 720 , 730 and 740 , the aerosol generating device generates an aerosol for inhalation by a user, and the controller is configured to control the power supplied to the heating element in accordance with the heating curve so as to adjust the temperature of the heating element.

[0253] One or more heating curves can be stored in Figure 1 , 2 The controller may be configured to select a heating curve during user operation of the device to generate an aerosol. For example, the aerosol generating device may include a device for identifying an aerosol generating article or an aerosol forming substrate, and the heating curve may be selected based on the result of the identification.

[0254] Figures 8 to 13 is a graph of heating element temperature versus time, showing an exemplary heating curve of the heating element during the main stage of heating the aerosol-forming substrate to form an aerosol for inhalation by a user. The heating curve shown defines the temperature value of each heating mode and the corresponding duration of each heating mode. However, it should be understood that the heating curve may include more than three heating modes.

[0255] Figures 8 to 13 Each heating curve in FIG. 1 shows a shaded area 810, 910, 1010, 1110, 1210 and 1310. This shaded area corresponds to the induction heating system ( Figure 2 ) or aerosol generating device with a resistive heating system ( Figure 6 ) during the preheating phase of the aerosol generating device.

[0256] Figures 8 to 13Each heating curve in shows that the temperature of the heating element increases from an initial temperature (not shown) to a first temperature in a first heating mode 820, 920, 1020, 1120, 1220, 1320. The controller may be configured to enter the first heating mode 820, 920, 1020, 1120, 1220, 1320 in response to a user actuating the aerosol generating device or detecting a user taking a puff. The temperature remains constant at the first temperature for the duration of the first time period. The initial temperature is greater than the ambient temperature and is between 140 and 170 degrees Celsius. In the case of inductive heating, the initial temperature may be the temperature reached during the calibration process 420. For example, after the maximum conductance is reached at the mound 320 during the calibration process, the heating element 44 may be allowed to cool to a temperature between the first calibration temperature and the second calibration temperature. The temperature to which the heating element 44 cools may be the initial temperature. In the case of resistive heating, the initial temperature may be the preheating temperature of the heating element 620.

[0257] The first temperature may be between 245 degrees C and 285 degrees C. As discussed above, heating the heating element to the first temperature of the heating element in the first heating mode 820, 920, 1020, 1120, 1220, 1320 overcomes the thermal inertia of the aerosol-forming substrate and improves the amount of vaporized desired volatile compounds (e.g., nicotine and aerosol former) in the aerosol inhaled by the user from the first puff.

[0258] After the first predetermined time period, the controller enters a second heating mode 830, 930, 1030, 1130, 1230, 1330. In the second heating mode, the controller adjusts the temperature of the heating element to one or more second temperatures during the second predetermined time period. The one or more second temperatures may be between 190 degrees Celsius and 220 degrees Celsius.

[0259] In the second heating mode 830, 930, 1030, 1130, 1230, 1330, the controller may adjust the temperature of the heating element to approximately correspond to the first temperature, such as Figure 8 as shown in .

[0260] In the second heating mode 830, 930, 1030, 1130, 1230, 1330, the controller may adjust the temperature of the heating element to be lower than the first temperature, such as Fig.10 , 11, 12 and 13. At the end of the first heating mode 820, 920, 1020, 1120, 1220, 1320, the heat will have diffused throughout the aerosol-forming substrate. Therefore, reducing the temperature of the heating element in the second heating mode enables the amount of evaporated desired volatile compounds in the aerosol inhaled by the user to remain consistent with the amount in the first heating mode 820, 920, 1020, 1120, 1220, 1320, thereby providing the user with the same sensory experience.

[0261] In the second heating mode 830, 930, 1030, 1130, 1230, 1330, the controller may adjust the temperature of the heating element to be higher than the first temperature, such as Fig.14 as shown in .

[0262] In the second heating mode 830, 930, 1030, 1130, 1230, 1330, the controller may adjust the temperature of the heating element to a second temperature for a duration of the second time period, such as Figure 8 , 9 Alternatively, in the second heating mode, the controller may adjust the temperature of the heating element in a plurality of continuous temperature steps. For example, Fig.10 Two temperature steps of equal duration are shown, wherein the temperature of the heating element during the first temperature step is lower than its temperature during the second temperature step. Fig.11 Two temperature steps are shown, wherein the temperature of the heating element during a first temperature step is lower than its temperature during a second temperature step, and wherein the duration of the first temperature step is shorter than the duration of the second temperature step.

[0263] In the third heating mode 840, 940, 1040, 1140, 1240, 1340, the controller is configured to adjust the temperature of the heating element to a third temperature. The temperature of the heating element is kept constant at the third temperature for a predetermined duration of the third time period. Figures 8 to 13 , the third temperature corresponds substantially to the first temperature. At this stage in the use process, the desired volatile compounds of the aerosol-forming substrate will have become depleted. Therefore, increasing the temperature of the heating element to substantially the first temperature enables the amount of evaporated desired volatile compounds in the aerosol inhaled by the user to remain consistent with the amounts in the first heating mode and the second heating mode.

[0264] The length of each of the predetermined time periods may be equal or may be different in length. For example, a first predetermined time period may be shorter than a subsequent second predetermined time period, e.g. Figure 8 , 9 , 10 and 12. Additionally or alternatively, the first predetermined time period may be shorter than the third predetermined time period, for example, Fig. 9 and 10 The second predetermined time period may be longer than at least one of the first predetermined time period and the third predetermined time period, such as Figures 8 to 13 The first predetermined time period and the third predetermined time period may have a duration, for example, Fig.12 as shown in .

[0265] The length of the first predetermined time period may be between 40 seconds and 150 seconds. The length of the second predetermined time period may be between 100 seconds and 280 seconds. The length of the third predetermined time period may be between 30 seconds and 120 seconds.

[0266] The length of the first predetermined time period is selected so that the aerosol-forming substrate can provide good delivery of the volatilized desired compound in the aerosol. The first predetermined time period being shorter than at least the second predetermined time period ensures good delivery of the aerosol to the user while ensuring consistency of the user experience throughout use.

[0267] The length of the second predetermined time period is longer than at least the first predetermined time period, particularly when the second temperature is lower than the first temperature, providing improved control over the amount of evaporated desired volatile compounds in the aerosol inhaled by the user, thereby providing a consistent user experience for as long as possible throughout the entire use process.

[0268] Fig.14 is a flow chart illustrating a method of controlling aerosol generation in one of the aerosol generating devices by heating a heating article inserted into a heating chamber of the aerosol generating device as described above.

[0269] When the user activates heating of the heating element as described above, the method starts at step 1410. For example, the user may press one or more buttons of the aerosol generating device to start heating of the heating element. Additionally or alternatively, the user may insert an aerosol generating article into a heating chamber of the aerosol generating device to start heating of the heating element.

[0270] Then, the method proceeds to step 1420, where the controller controls the power provided to the heating system to increase the temperature of the heating element from the ambient temperature to the initial temperature. During step 1420, the controller is in a preheating mode and maintains the temperature of the heating element at the initial temperature for a predetermined period of time.

[0271] When the aerosol generating device is operated by means of an induction ( Figure 2 When the aerosol generating device of the present invention heats the heating element, the preheating mode then performs a calibration process to obtain a first calibration value and a second calibration value at step 1430. As described above, the controller uses the first calibration value and the second calibration value to adjust the temperature of the susceptor.

[0272] At step 1440, the controller enters a first heating mode for an aerosol generating device using resistive heating after step 1420 and for an aerosol generating device using inductive heating after step 1430. In the first heating mode, the controller adjusts the temperature of the heating element to increase the temperature from an initial temperature to a first temperature. The first temperature is maintained for a first predetermined period of time.

[0273] At the end of the first predetermined time period, the controller enters a second heating mode at step 1450. In the second heating mode, the controller adjusts the temperature of the heating element to a second temperature. The second temperature may be maintained for a second predetermined time period. Alternatively, the second temperature may be a first step of a plurality of temperature steps, each temperature step having a predefined duration, wherein the sum of the predefined durations of each temperature step is the duration of the second predetermined time period of the second heating mode. The second temperature may be lower than, substantially equal to, or greater than the first temperature.

[0274] At the end of the second predetermined time period, the controller enters a third heating mode at step 1460. In the third heating mode, the controller adjusts the temperature of the heating element to a third temperature. The third temperature is maintained for a third predetermined time period. The third temperature is substantially equal to the first temperature and is maintained constant for the duration of the third time period.

[0275] It should be understood that these figures are for illustrative purposes and are not drawn to scale. In addition, it should be understood that the aerosol-generating articles and aerosol-generating devices shown in the drawings and described in detail above may have additional elements beyond those discussed. Likewise, an aerosol-generating article or aerosol-generating device according to the embodiments discussed herein may have fewer elements. In addition, it will be apparent to one of ordinary skill in the art that the various dimensions of the elements discussed with respect to the various embodiments discussed herein are merely exemplary, and suitable alternative dimensions may be selected for the various elements.

[0276] For the purpose of this specification and the appended claims, unless otherwise stated, all numbers indicating amounts, quantities, percentages, etc. should be understood to be modified by the term "about" in all cases. Moreover, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein that may or may not be specifically listed herein. Therefore, in this context, the number A is understood to be A±10%A. In this context, the number A can be regarded as including the numerical value within the general standard error for the measurement of the attribute modified by the number A. In certain cases used in the appended claims, the number A may deviate from the percentages listed above, provided that the amount of A deviation does not substantially affect the basic and novel features of the invention claimed for protection. Moreover, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein that may or may not be specifically listed herein. In addition, in the context of the present invention, the expression that the number A "roughly corresponds to" the number B should be understood as the number A equals B±10% of B.

Claims

1. A method for controlling aerosol generation in an aerosol generating device, the device comprising: a heating chamber configured to at least partially receive an aerosol-generating article comprising an aerosol-forming substrate; a heating system associated with a heating element configured to heat the aerosol-forming substrate from within the aerosol-forming substrate; and a power source for providing power to the heating system, the method comprising: receiving the aerosol-generating article from the heating chamber, wherein the aerosol-forming substrate has a total aerosol-former content of greater than 30% by weight, and wherein the aerosol-forming substrate is a solid or a gel; and The aerosol-forming substrate is heated to form an aerosol for inhalation by a user by controlling the power to: increasing the temperature of the heating element from an initial temperature to a first temperature; and maintaining the temperature of the heating element constant at the first temperature for a duration of a first predetermined time period, wherein the first temperature is between 245 degrees Celsius and 285 degrees Celsius, The method further comprises controlling the power to increase the temperature of the heating element from ambient temperature to the initial temperature during a preheating period prior to the first predetermined period.

2. The method of claim 1, wherein controlling the power further comprises adjusting the temperature of the heating element to a second temperature during a second predetermined time period, wherein the second predetermined time period is after the first predetermined time period, and wherein the second temperature is lower than the first temperature. 3 . The method of claim 2 , wherein adjusting the temperature of the heating element to the second temperature during the second time period comprises two consecutive temperature steps. The method according to claim 3 , wherein the temperature of the first temperature step is lower than the temperature of the second temperature step.

5. The method of one of claims 2 to 4, wherein controlling the power further comprises adjusting the temperature of the heating element to a third temperature during a third predetermined time period, wherein the third predetermined time period is after the second predetermined time period, wherein the third temperature substantially corresponds to the first temperature.

6. A system comprising: an aerosol-generating article comprising an aerosol-forming substrate having a total aerosol-former content greater than or equal to 30% by weight, and wherein the aerosol-former substrate is a solid or a gel; as well as An aerosol generating device, the aerosol generating device comprising: a heating chamber configured to at least partially receive the aerosol-generating article; a heating system associated with a heating element configured to heat the aerosol-forming substrate from within the aerosol-forming substrate; a power source for providing power to the heating system; and a controller configured to control the power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user to: increasing the temperature of the heating element from an initial temperature to a first temperature; and maintaining the temperature of the heating element constant at the first temperature for a duration of a first predetermined time period, wherein the first temperature is between 245 degrees Celsius and 285 degrees Celsius, Wherein the controller is further configured to increase the temperature of the heating element from ambient temperature to the initial temperature during a preheating period prior to the first predetermined period of time.

7. A system according to claim 6, wherein controlling the power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user also includes adjusting the temperature of the heating element to a second temperature during a second predetermined time period, wherein the second predetermined time period is after the first predetermined time period, and wherein the second temperature is lower than the first temperature.

8. A system according to claim 7, wherein controlling the power during heating of the aerosol-forming substrate to form an aerosol for inhalation by a user also includes adjusting the temperature of the heating element to a third temperature during a third predetermined time period, wherein the third predetermined time period is after the second predetermined time period, and wherein the third temperature substantially corresponds to the first temperature.

9. The system according to one of claims 6 to 8, wherein the aerosol-forming substrate further comprises the heating element, and wherein the heating system comprises an induction coil for inductively heating the heating element.

10. The system of claim 9, wherein the controller is further configured to: During a preheating period prior to the first predetermined period, the power is controlled to increase the temperature of the heating element from ambient temperature to the initial temperature.

11. The system of one of claims 9 or 10, wherein the controller is further configured to calibrate the heating element after the preheating time period and before the first time period.

12. System according to one of claims 6 to 8, wherein the heating system comprises the heating element, the heating element being a resistive heating element.

13. The system of claim 12, wherein the controller is further configured to: During a preheating period prior to the first predetermined period, the power is controlled to increase the temperature of the heating element from ambient temperature to the initial temperature.

14. The system according to one of claims 8 to 13, wherein the aerosol-forming substrate does not comprise tobacco.

15. The system according to one of claims 6 to 14, wherein the aerosol-forming substrate comprises water, wherein the aerosol-forming substrate has a water content of between 5% and 35% by weight.

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