RU2850713C1 - Device and system for generating aerosol, containing induction heating device, and method of their operation - Google Patents

Abstract

FIELD: heating systems.

SUBSTANCE: method for controlling aerosol delivery in an aerosol generating device includes performing a calibration process to measure calibration values associated with a current collector. A heating device is provided with the capability of induction heating the current collector based on the calibration values. The calibration process includes: i) regulating the power supplied to the heating device to ensure an increase in the temperature of the current collector; ii) monitoring the conductivity or resistance value associated with the current collector; iii) interrupting the power supply to the heating device when the conductivity value reaches a maximum or when the resistance value reaches a minimum; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a minimum or until the resistance value reaches a maximum.

EFFECT: ensuring accurate and reliable temperature control and regulation of the induction heating device.

25 cl, 8 dwg

Description

The present invention relates to an induction heating device for heating an aerosol-forming substrate. The present invention further relates to an aerosol-generating device comprising such an induction heating device, and a method for controlling aerosol formation in the aerosol-generating device.

Aerosol-generating devices may include an electrically controlled heat source capable of heating an aerosol-forming substrate to produce an aerosol. The electrically controlled heat source may be an induction heating device. Induction heating devices typically include an inductor inductively coupled to a susceptor. The inductor generates an alternating magnetic field, which causes heating in the susceptor. Typically, the susceptor is in direct contact with the aerosol-forming substrate, and heat is transferred from the susceptor to the aerosol-forming substrate primarily by conduction. The temperature of the aerosol-forming substrate can be controlled by adjusting the temperature of the susceptor. Therefore, for such aerosol-generating devices, it is important to precisely monitor and regulate the temperature of the susceptor to ensure optimal aerosol generation and delivery to the user.

It would be desirable to provide temperature control and regulation of an induction heating device that is accurate, reliable and inexpensive.

According to an embodiment of the present invention, a method for regulating the production of an aerosol in an aerosol generating device is provided. The aerosol generating device comprises a heating device and a power source for supplying power to the heating device. The method comprises: performing a calibration process for measuring calibration values associated with a current collector (=suction device), wherein the heating device is configured to inductively heat the current collector based on the calibration values. The calibration process comprises the following steps: i) regulating the power supplied to the heating device to ensure an increase in the temperature of the current collector; ii) monitoring the conductivity or resistance value associated with the current collector; iii) interrupting the power supply to the heating device when the conductivity value reaches a maximum, or interrupting the power supply to the heating device when the resistance value reaches a minimum, wherein the conductivity value at maximum conductivity or the resistance value at minimum resistance is a second calibration value associated with the current collector; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a minimum, or monitoring the resistance value associated with the current collector until the resistance value reaches a maximum, wherein the conductivity value at minimum conductivity or the resistance value at maximum resistance is a first calibration value associated with the current collector.

The calibration process is fast and reliable, without delaying aerosol generation. Furthermore, the calibration process increases the flexibility and cost-effectiveness of the aerosol-generating device, as it can be calibrated (and recalibrated) for more than one pantograph type at any stage of the aerosol-generating device's lifecycle.

A current collector, which is preferably a current collector, may comprise a first material having a first Curie temperature and a second material having a second Curie temperature. A second calibration temperature of the current collector, associated with a second calibration conductivity value, may correspond to the second Curie temperature of the second material. The first and second materials are preferably two separate materials that are connected together and therefore in close physical contact with each other, while ensuring that both materials have the same temperature due to thermal action. The two materials are preferably two layers or strips that are connected along one of their main surfaces. The current collector may further comprise an additional third layer of material. The third layer of current collector material is preferably made of the first current collector material. The thickness of the third layer of current collector material is preferably less than the thickness of the layer of the second current collector material.

The calibration process can be performed while the user is working with the aerosol-generating device. Performing calibration while the user is working with the aerosol-generating device means that the calibration values used to regulate the heating process are more accurate and reliable than if the calibration process were performed in production. This also increases flexibility and cost-effectiveness, as the aerosol-generating device can be calibrated for more than one type of susceptor. This is especially important if the susceptor is part of a separate aerosol-generating device. In such circumstances, calibration in production is not possible.

The method may further include regulating the power supplied to the induction heating device to maintain the conductivity value associated with the current collector between the first calibration value and the second calibration value.

The induction heating device may comprise a DC/AC converter and an inductor connected to the DC/AC converter. The current collector may be configured to be inductively coupled to the inductor. The conductivity value or resistance value is preferably determined based on the DC supply voltage of the power source and generates a DC current drawn from the power source. The DC current drawn from the power source is preferably measured at the input side of the DC/AC converter. Preferably, the DC supply voltage is further measured at the input side of the DC/AC converter. This is due to the fact that there is a monotonic relationship between the actual admittance (which cannot be determined if the susceptor is part of an aerosol-generating article) of the susceptor and the conditional admittance thus defined (since the susceptor will impart admittance to the LCR (DC to AC converter) circuit to which it will be connected, since most of the load (R) will be due to the resistance of the susceptor. The admittance is equal to 1/R. Therefore, references to the admittance of the susceptor should be understood as referring to the conditional admittance if the susceptor is part of a separate aerosol-generating article.

Regulating the power supplied to the induction heating device may include regulating the power supplied to the induction heating device to provide a stepwise increase in the conductivity value associated with the susceptor from a first operating conductivity value to a second operating conductivity value. The temperature of the susceptor associated with the first operating conductivity value may be sufficient to cause the aerosol to form from the aerosol-forming substrate.

The method may further include regulating the power supplied to the induction heating device to maintain the resistance value associated with the susceptor between the first calibration value and the second calibration value. Regulating the power supplied to the induction heating device may include regulating the power supplied to the induction heating device to ensure a stepwise decrease in the resistance value associated with the susceptor from the first operating resistance value to the second operating resistance value. The temperature of the susceptor associated with the first operating resistance value may be sufficient for the aerosol formation by the aerosol-forming substrate.

Carrying out the calibration process may further include: v) when the conductivity value reaches a minimum or when the resistance value reaches a maximum, adjusting the power supplied to the heating device to ensure that the temperature of the current collector increases; vi) monitoring the conductivity value or the resistance value associated with the current collector; vii) interrupting the power supply to the heating device when the conductivity value reaches a second maximum or when the resistance value reaches a second minimum, wherein the conductivity value at the second maximum is a fourth calibration value associated with the current collector or the resistance value at the second maximum is a fourth calibration value associated with the current collector; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a second minimum, wherein the conductivity value at the second minimum is a third calibration value associated with the current collector, or monitoring the resistance value associated with the current collector until the resistance value reaches a second maximum, wherein the resistance value at the second maximum is a third calibration value associated with the current collector.

The method may further include regulating the power supplied to the induction heating device to maintain the conductivity value associated with the current collector between the third calibration value and the fourth calibration value.

Repeating the calibration process steps and using the conductivity calibration values obtained during the calibration process repetitions significantly improves subsequent temperature control because the heat has had more time to distribute into the substrate.

regulating the power supplied to the induction heating device may include regulating the power supply to the induction heating device to provide a stepwise increase in the conductivity value associated with the susceptor from a first operating conductivity value to a second operating conductivity value.

Regulating the power supplied to the induction heating device to ensure a gradual increase in the susceptor temperature allows for aerosol generation over an extended period of time, spanning the user's entire experience, whether over multiple puffs (e.g., 14 puffs) or a set time interval (e.g., 6 minutes), while the delivered substances (nicotine, flavorings, aerosol volume, etc.) remain virtually constant for each puff throughout the user's experience. Specifically, the gradual increase in susceptor temperature prevents aerosol delivery from depleting due to substrate depletion and reduced thermal diffusion over time. Furthermore, the gradual increase in temperature allows heat to diffuse within the substrate at each stage.

The method may further include regulating the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the third calibration value and the fourth calibration value. Regulating the power supplied to the induction heating device may include regulating the power supplied to the induction heating device to ensure a stepwise decrease in the resistance value associated with the current collector from the first operating resistance value to the second operating resistance value.

The aerosol-generating device may be configured to removably accommodate an aerosol-generating article. The aerosol-generating article may comprise a susceptor and an aerosol-generating substrate. The calibration process may be performed in response to detection of the aerosol-generating article.

The calibration process may be performed in response to detection of user input.

The calibration process can be performed in response to detection of a control signal associated with the end of the preheating process. The preheating process can have a specified duration.

The method may further include performing a preheating process. The preheating process may include the following steps: i) regulating the power supplied to the induction heating device to ensure an increase in the temperature of the susceptor; ii) monitoring the conductivity or resistance value associated with the susceptor; and iii) interrupting the power supply to the induction heating device when the conductivity value reaches a minimum or when the resistance value reaches a maximum.

The preheating process allows heat to diffuse into the substrate before the calibration process begins, thereby further increasing the reliability of the calibration values.

If the conductivity value reaches a minimum or the resistance value reaches a maximum before the end of the specified duration of the preheating process, steps i) to iii) of the preheating process may be repeated until the end of the specified duration of the preheating process.

The specified duration allows heat to diffuse through the substrate within the time required to reach the minimum calibration value measured during the calibration process, regardless of the substrate's physical state (e.g., whether the substrate is dry or wet). This ensures the reliability of the calibration process.

If the conductivity value does not reach a minimum or the resistance value does not reach a maximum within a specified duration of the preheating process, a control signal may be generated to stop the operation of the aerosol generating device.

Preferably, the susceptor is contained in an aerosol-generating article that can be inserted into the aerosol-generating device. Aerosol-generating articles that are not designed for use with the aerosol-generating device will not exhibit the same behavior as authorized aerosol-generating articles. In particular, the conductivity associated with the susceptor will not reach a minimum during the specified preheating period. Accordingly, this prevents the use of unauthorized aerosol-generating articles.

The aerosol-generating device may be configured to accommodate an aerosol-generating article. The aerosol-generating article may comprise a susceptor and an aerosol-generating substrate. The preheating process may be performed in response to detection of the aerosol-generating article.

The preheating process may be performed in response to detection of user input.

According to another embodiment of the present invention, an aerosol generating device is provided. The aerosol generating device comprises a power source for supplying a DC and DC supply voltage, and a power supply electronic circuit (power supply electronics) connected to the power source. The power supply electronic circuit comprises a DC/AC converter and an inductor connected to the DC/AC converter for generating an alternating magnetic field when excited by an alternating current from the DC/AC converter, wherein the inductor is configured to be connected to a current collector. The current collector is configured to heat an aerosol-forming substrate. The power supply electronic circuit further comprises a controller. The controller is configured to perform a calibration process for measuring calibration values associated with the current collector. The power supply electronic circuit is configured to inductively heat the current collector based on the calibration values. The calibration process includes the following steps: i) regulating the power supplied to the inductor to ensure an increase in the temperature of the current collector; ii) monitoring the conductivity or resistance value associated with the current collector; iii) interrupting the supply of power to the inductor when the conductivity value reaches a maximum or interrupting the supply of power to the inductor when the resistance value reaches a minimum, wherein the conductivity value at maximum conductivity or the resistance value at minimum resistance is a second calibration value associated with the current collector; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a minimum or monitoring the resistance value associated with the current collector until the resistance value reaches a maximum, wherein the conductivity value at minimum conductivity or the resistance value at maximum resistance is a first calibration value associated with the current collector.

The second operating temperature of the current collector, associated with the second conductivity calibration value, may correspond to the Curie temperature of the current collector material.

The calibration process can be performed while the user is operating the aerosol generating device.

The controller may be further configured to control (regulate) the power supplied to the inductor to maintain the conductivity value associated with the current collector between the first calibration value and the second calibration value.

Regulating the power supplied to the inductor may include regulating the power supplied to the inductor to provide a stepwise increase in the conductivity value associated with the current collector, from a first operating conductivity value to a second operating conductivity value. The temperature of the current collector associated with the first operating conductivity value may be sufficient to generate an aerosol from the aerosol-forming substrate.

The controller may be further configured to control (regulate) the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the first calibration value and the second calibration value. Regulating the power supplied to the induction heating device may include regulating the power supplied to the induction heating device to ensure a stepwise decrease in the resistance value associated with the current collector from the first operating resistance value to the second operating resistance value, wherein the temperature of the current collector associated with the first operating resistance value is sufficient for the aerosol formation by the aerosol-forming substrate.

Carrying out the calibration process may further include: v) when the conductivity value reaches a minimum or when the resistance value reaches a maximum, adjusting the power supplied to the heating device to ensure that the temperature of the current collector increases; vi) monitoring the conductivity value or the resistance value associated with the current collector; vii) interrupting the power supply to the inductor when the conductivity value reaches a second maximum or when the resistance value reaches a second minimum, wherein the conductivity value at the second maximum is a fourth calibration value associated with the current collector or the resistance value at the second maximum is a fourth calibration value associated with the current collector; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a second minimum, wherein the conductivity value at the second minimum is a third calibration value associated with the current collector, or monitoring the resistance value associated with the current collector until the resistance value reaches a second maximum, wherein the resistance value at the second maximum is a third calibration value associated with the current collector.

the controller may be further configured to control (regulate) the power supplied to the inductor to maintain the conductivity value associated with the current collector between the third conductivity calibration value and the fourth conductivity calibration value.

regulating the power supplied to the inductor may include regulating the power supply to the inductor to provide a stepwise increase in the conductivity value associated with the current collector from a first operating conductivity value to a second operating conductivity value.

The controller may be further configured to control (regulate) the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the third calibration value and the fourth calibration value.

Regulating the power supplied to the induction heating device may include regulating the power supplied to the induction heating device to gradually decrease the resistance value associated with the susceptor from a first operating resistance value to a second operating resistance value. The controller may be configured to perform a calibration process in response to detecting an aerosol-generating article containing the susceptor.

The controller may be configured to perform a calibration process in response to detecting a user input.

The controller may be configured to perform a calibration process in response to detecting a control signal associated with the end of a preheating process, wherein the preheating process has a specified duration.

The controller may be further configured to perform a preheating process. The preheating process may include the following steps: i) regulating the power supplied to the inductor to ensure an increase in the temperature of the current collector; ii) monitoring the conductivity or resistance value associated with the current collector; and iii) interrupting the power supply to the inductor when the conductivity value reaches a minimum or when the resistance value reaches a maximum.

The controller may be configured so that if the conductivity value reaches a minimum or the resistance value reaches a maximum before the end of the specified duration of the preheating process, steps i)-iii) of the preheating process are repeated until the end of the specified duration of the preheating process.

The controller may be configured to generate a control signal to stop the operation of the aerosol generating device if the conductivity value of the current collector does not reach a minimum or the resistance value does not reach a maximum within a specified duration of the preheating process.

The controller may be configured to perform a preheating process in response to detecting an aerosol generating article containing a susceptor.

The controller may be configured to perform the preheating process in response to detecting a user input.

The aerosol-generating device may further comprise a housing having a cavity configured to accommodate an aerosol-generating article. The aerosol-generating article may comprise an aerosol-forming substrate and a current collector.

According to another embodiment of the present invention, an aerosol-generating system is provided. The aerosol-generating system comprises an aerosol-generating device of the aerosol-generating article described above. The aerosol-generating article comprises an aerosol-forming substrate and a current collector.

The current collector may comprise a first current-receiving material and a second current-receiving material, wherein the first current-receiving material is in physical contact with the second current-receiving material. The first current-receiving material may have a first Curie temperature, and the second current-receiving material may have a second Curie temperature. The second Curie temperature may be lower than the first Curie temperature. The second calibration temperature may correspond to the Curie temperature of the second current-receiving material.

As used herein, the term "aerosol-generating device" refers to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-generating device may interact with one or both of an aerosol-generating article containing the aerosol-forming substrate and a cartridge containing the aerosol-forming substrate. In some examples, the aerosol-generating device may heat the aerosol-forming substrate to facilitate the release of volatile compounds from the substrate. An electrically powered aerosol-generating device may include an atomizer, such as an electric heater, for heating the aerosol-forming substrate to form an aerosol.

For the purposes of this document, the term "aerosol-generating system" refers to the combination of an aerosol-generating device and an aerosol-generating substrate. When the aerosol-generating substrate forms part of an aerosol-generating article, the aerosol-generating system refers to the combination of the aerosol-generating device and the aerosol-generating article. In an aerosol-generating system, the aerosol-generating substrate and the aerosol-generating device interact to generate an aerosol.

For the purposes of this document, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form an aerosol. The volatile compounds can be released by heating or burning the aerosol-forming substrate. As an alternative to heating or burning, in some cases, the volatile compounds can be released through a chemical reaction or mechanical action, such as ultrasonication. The aerosol-forming substrate can be solid or liquid, or may contain both solid and liquid components. The aerosol-forming substrate can be part of an aerosol-generating article.

As used herein, the term "aerosol-generating article" refers to an article containing an aerosol-forming substrate capable of releasing volatile compounds that can form an aerosol. An aerosol-generating article may be disposable. An aerosol-generating article containing an aerosol-forming substrate containing tobacco may be referred to herein as a tobacco stick.

The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise tobacco, for example, a tobacco-containing material containing volatile tobacco flavor compounds that are released from the aerosol-forming substrate upon heating. In preferred embodiments, the aerosol-forming substrate may comprise homogenized tobacco material, such as leaf tobacco. The aerosol-forming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavor compounds that are released from the substrate upon heating. The aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may further comprise an aerosol-forming agent. Examples of suitable aerosol-forming agents include glycerin and propylene glycol.

For the purposes of this document, "aerosol cooling element" refers to a component of an aerosol-generating device located downstream of the aerosol-generating substrate. Thus, during use, the aerosol generated by volatile compounds released from the aerosol-generating substrate passes through the aerosol cooling element and is cooled by it before inhalation by the user. An aerosol cooling element has a large surface area but produces a low pressure drop. Filters and other mouthpieces that produce a high pressure drop, such as filters made of fiber bundles, are not considered aerosol cooling elements. Chambers and cavities in an aerosol-generating device are not considered aerosol cooling elements.

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

In the context of this document, the term "current collector" refers to an element containing a material capable of converting magnetic field energy into heat. When the current collector is exposed to an alternating magnetic field, the current collector heats up. Heating of the current collector may be the result of at least one of hysteresis losses and eddy currents induced in the current collector, depending on the electrical and magnetic properties of the current collector material.

In the context of this document, with respect to an aerosol-generating device, the terms "upstream" and "front," as well as "downstream" and "rear," are used to describe the relative positions of components or portions of components of an aerosol-generating device with respect to the direction in which air flows through the aerosol-generating device during use. Aerosol-generating devices according to the present invention include a proximal end through which the aerosol exits the device during use. The proximal end of an aerosol-generating device may also be referred to as the mouthpiece end or the downstream end. The mouthpiece end is located downstream of the distal end. The distal end of an aerosol-generating article may also be referred to as the upstream end. Components or portions of components of an aerosol generating device may be described as being upstream or downstream relative to one another based on their relative positions with respect to the airflow path of the aerosol generating device.

In the context of this document, with respect to an aerosol-generating article, the terms "upstream" and "front," as well as "downstream" and "rear," are used to describe the relative positions of components or portions of components of the aerosol-generating article with respect to the direction in which air flows through the aerosol-generating article during use. The aerosol-generating article of the present invention includes a proximal end through which the aerosol exits the article during use. The proximal end of the aerosol-generating article may also be referred to as the mouthpiece end or the downstream end. The mouthpiece end is located 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 upstream or downstream relative to one another based on their relative positions between the proximal end of the aerosol-generating article and the distal end of the aerosol-generating article. The forward side 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 side 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.

In the context of this document, the term "inductive coupling" refers to the heating of a current collector when an alternating magnetic field passes through it. Heating can be caused by the generation of eddy currents in the current collector. Heating can also be caused by magnetic hysteresis losses.

For the purposes of this document, the term "inhalation" refers to the action of the user drawing the aerosol into their body through their mouth or nose.

The present 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.

Example Ex1: A method for regulating the production of an aerosol in an aerosol generating device, an aerosol generating device comprising a heating device and a power source for supplying power to the heating device, and a method which comprises: performing a calibration process for measuring calibration values associated with a susceptor, wherein the heating device is configured to inductively heat the susceptor based on the calibration values, and wherein the calibration process comprises the following steps: i) regulating the power supplied to the heating device to provide an increase in the temperature of the susceptor; ii) monitoring a conductivity or resistance value associated with the susceptor; iii) interrupting the power supply to the heating device when the conductivity value reaches a maximum or interrupting the power supply to the heating device when the resistance value reaches a minimum, wherein the conductivity value at maximum conductivity or the resistance value at minimum resistance is a second calibration value associated with the susceptor; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a minimum, or monitoring the resistance value associated with the current collector until the resistance value reaches a maximum, wherein the conductivity value at minimum conductivity or the resistance value at maximum resistance is a first calibration value associated with the current collector.

Example Ex2: The method according to example Ex1, wherein the current collector comprises a first material having a first Curie temperature and a second material having a second Curie temperature, wherein the second Curie temperature is lower than the first Curie temperature, and wherein the second calibration temperature of the current collector, associated with the second calibration value of conductivity, corresponds to the second Curie temperature of the second material.

Example Ex3: The method according to example Ex1 or Ex2, wherein the calibration process is performed while the user is operating the aerosol generating device.

Example Ex4: The method according to any of examples Ex1-Ex3, further comprising regulating the power supplied to the induction heating device to maintain the conductivity value associated with the current collector between the first calibration value and the second calibration value.

Example Ex5: The method according to example Ex4, wherein adjusting the power supplied to the induction heating device comprises adjusting the power supplied to the induction heating device to provide a stepwise increase in the conductivity value associated with the current collector from a first operating conductivity value to a second operating conductivity value, wherein the temperature of the current collector associated with the first operating conductivity value is sufficient for the formation of an aerosol by the aerosol-forming substrate.

Example Ex6: The method according to any of examples Ex1-Ex3, further comprising regulating the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the first calibration value and the second calibration value.

Example Ex7: The method according to example Ex6, wherein adjusting the power supplied to the induction heating device comprises adjusting the power supplied to the induction heating device to provide a stepwise decrease in the resistance value associated with the current collector from a first operating resistance value to a second operating resistance value, wherein the temperature of the current collector associated with the first operating resistance value is sufficient for the formation of an aerosol by the aerosol-forming substrate.

Example Ex8: The method according to any of examples Ex1 to Ex3, wherein performing the calibration process further comprises: v) when the conductivity value reaches a minimum, or when the resistance value reaches a maximum, adjusting the power supplied to the heating device to ensure that the temperature of the current collector increases; vi) monitoring the conductivity value or the resistance value associated with the current collector; vii) interrupting the power supply to the heating device when the conductivity value reaches a second maximum or when the resistance value reaches a second minimum, wherein the conductivity value at the second maximum is a fourth calibration value associated with the current collector, or the resistance value at the second maximum is a fourth calibration value associated with the current collector; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a second minimum, wherein the conductivity value at the second minimum is a third calibration value associated with the current collector, or monitoring the resistance value associated with the current collector until the resistance value reaches a second maximum, wherein the resistance value at the second maximum is a third calibration value associated with the current collector.

Example Ex9: The method according to example Ex8, further comprising adjusting the power supplied to the induction heating device to maintain the conductivity value associated with the current collector between the third calibration value and the fourth calibration value.

Example Ex10: The method according to example Ex9, wherein the regulation of the power supplied to the induction heating device comprises regulation of the power supply for the induction heating device to provide a stepwise increase in the conductivity value associated with the current collector from a first operating conductivity value to a second operating conductivity value.

Example Ex11: The method according to example Ex8, further comprising regulating the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the third calibration value and the fourth calibration value.

Example Ex12: The method according to example Ex11, wherein the regulation of the power supplied to the induction heating device comprises regulation of the power supplied to the induction heating device to provide a stepwise decrease in the resistance value associated with the current collector from a first operating resistance value to a second operating resistance value.

Example Ex13: The method according to any of examples Ex1-Ex12, wherein the aerosol generating device is configured to removably accommodate an aerosol generating article, wherein the aerosol generating article comprises a current collector and an aerosol forming substrate, and wherein the calibration process is performed in response to detection of the aerosol generating article.

Example Ex14: The method according to any of examples Ex1-Ex12, wherein the calibration process is performed in response to detecting user input.

Example Ex15: The method according to any of the examples Ex1-Ex12, wherein the calibration process is performed in response to detection of a control signal associated with the end of the preheating process, wherein the preheating process has a specified duration.

Example Ex16: The method according to example Ex15, further comprising performing a pre-heating process, wherein the pre-heating process comprises the following steps: i) adjusting the power supplied to the induction heating device to ensure an increase in the temperature of the susceptor; ii) monitoring the conductivity or resistance value associated with the susceptor; and iii) interrupting the power supply to the induction heating device when the conductivity value reaches a minimum or when the resistance value reaches a maximum.

Example Ex17: The method according to example Ex16, further comprising, if the conductivity value reaches a minimum or if the resistance value reaches a maximum before the end of the predetermined duration of the preheating process, repeating steps i) to ii) from the preheating process until the end of the predetermined duration of the preheating process

Example Ex18: The method according to example Ex15 or Ex16, further comprising: if the conductivity value does not reach a minimum or if the resistance value does not reach a maximum within a given duration of the preheating process, generating a control signal to stop the operation of the aerosol generating device.

Example Ex19: The method according to any of examples Ex15-Ex18, wherein the aerosol generating device is configured to accommodate an aerosol generating article, wherein the aerosol generating article comprises a current collector and an aerosol forming substrate, and wherein the preheating process is performed in response to detection of the aerosol generating article.

Example Ex20: The method according to any of examples Ex15-Ex18, wherein the preheating process is performed in response to detecting a user input.

Example Ex21: An aerosol generating device comprising: a power source for supplying a DC supply voltage and a DC current; and a power supply electronic circuit connected to the power source, wherein the power supply electronic circuit comprises: a DC to AC converter; an inductor connected to the DC to AC converter for generating an alternating magnetic field when excited by an AC current from the DC to AC converter, wherein the inductor is configured to be connected to a current collector, wherein the current collector is configured to heat an aerosol-forming substrate; and a controller configured to: perform a calibration process for measuring calibration values associated with the current collector, wherein the power supply electronic circuit is configured to inductively heat the current collector based on the calibration values, and wherein the calibration process includes the following steps: i) adjusting the power supplied to the inductor to provide an increase in the temperature of the current collector; ii) monitoring a conductivity or resistance value associated with the current collector; iii) interrupting the supply of power to the inductor when the conductivity value reaches a maximum, or interrupting the supply of power to the inductor when the resistance value reaches a minimum, wherein the conductivity value at maximum conductivity or the resistance value at minimum resistance is a second calibration value associated with the current collector; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a minimum, or monitoring the resistance value associated with the current collector until the resistance value reaches a maximum, wherein the conductivity value at minimum conductivity or the resistance value at maximum resistance is a first calibration value of conductivity associated with the current collector.

Example Ex22: An aerosol generating device according to example Ex21, wherein the second operating temperature of the current collector associated with the second conductivity calibration value corresponds to the Curie temperature of the current collector material.

Example Ex23: An aerosol generating device according to example Ex21 or Ex22, wherein the calibration process is performed while the user is operating the aerosol generating device.

Example Ex24: An aerosol generating device according to any of examples Ex21-23, wherein the controller is further configured to control (regulate) the power supplied to the inductor to maintain the conductivity value associated with the current collector between the first calibration value and the second calibration value.

Example Ex25: An aerosol generating device according to example Ex24, wherein regulating the power supplied to the inductor comprises regulating the power supplied to the inductor to provide a stepwise increase in the conductivity value associated with the current collector from a first operating conductivity value to a second operating conductivity value, wherein the temperature of the current collector associated with the first operating conductivity value is sufficient for the formation of an aerosol by an aerosol-forming substrate.

Example Ex26: An aerosol generating device according to any of examples Ex21-Ex23, wherein the controller is further configured to control (regulate) the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the first calibration value and the second calibration value.

Example Ex27: An aerosol generating device according to example Ex26, wherein regulating the power supplied to the induction heating device comprises regulating the power supplied to the induction heating device to provide a stepwise decrease in the resistance value associated with the current collector from a first operating resistance value to a second operating resistance value, wherein the temperature of the current collector associated with the first operating resistance value is sufficient for the formation of an aerosol by the aerosol-forming substrate.

Example Ex28: An aerosol generating device according to any of examples Ex21 to Ex23, wherein performing the calibration process further comprises: v) when the conductivity value reaches a minimum or when the resistance value reaches a maximum, adjusting the power supplied to the heating device to ensure that the temperature of the susceptor increases; vi) monitoring the conductivity value or the resistance value associated with the susceptor; vii) interrupting the power supply to the inductor when the conductivity value reaches a second maximum or when the resistance value reaches a second minimum, wherein the conductivity value at the second maximum is a fourth calibration value associated with the susceptor or the resistance value at the second maximum is a fourth calibration value associated with the susceptor; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a second minimum, wherein the conductivity value at the second minimum is a third calibration value associated with the current collector, or monitoring the resistance value associated with the current collector until the resistance value reaches a second maximum, wherein the resistance value at the second maximum is a third calibration value associated with the current collector.

Example Ex29: An aerosol generating device according to example Ex28, wherein the controller is further configured to control (regulate) the power supplied to the inductor to maintain the conductivity value associated with the current collector between the third calibration value and the fourth calibration value.

Example Ex30: An aerosol generating device according to example Ex29, wherein the regulation of the power supplied to the inductor comprises regulating the power supply for the inductor to provide a stepwise increase in the conductivity value associated with the current collector from a first operating conductivity value to a second operating conductivity value.

Example Ex31: An aerosol generating device according to example Ex28, wherein the controller is further configured to control (regulate) the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the third calibration value and the fourth calibration value.

Example Ex32: An aerosol generating device according to example Ex29, wherein regulating the power supplied to the induction heating device comprises regulating the power supplied to the induction heating device to provide a stepwise decrease in the resistance value associated with the current collector from a first operating resistance value to a second operating resistance value.

Example Ex33: An aerosol generating device according to any of examples Ex21-Ex32, wherein the controller is configured to perform a calibration process in response to detecting an aerosol generating article containing a current collector.

Example Ex34: An aerosol generating device according to any of examples Ex21-Ex32, wherein the controller is configured to perform a calibration process in response to detecting user input.

Example Ex35: An aerosol generating device according to any of examples Ex21-32, wherein the controller is configured to perform a calibration process in response to detecting a control signal associated with the end of a preheating process, wherein the preheating process has a specified duration.

Example Ex36: An aerosol generating device according to example Ex35, wherein the controller is further configured to perform a pre-heating process, wherein the pre-heating process comprises the following steps: i) regulating the power supplied to the inductor to ensure an increase in the temperature of the current collector; ii) monitoring the conductivity or resistance value associated with the current collector; and iii) interrupting the power supply to the inductor when the conductivity value reaches a minimum or when the resistance value reaches a maximum.

Example Ex37: An aerosol generating device according to example Ex36, wherein the controller is configured to, if the conductivity value reaches a minimum or the resistance value reaches a maximum before the end of the predetermined duration of the preheating process, repeat steps i) to iii) of the preheating process until the end of the predetermined duration of the preheating process.

Example Ex38: An aerosol generating device according to example Ex36 or Ex37, wherein the controller is configured to, if the conductivity value of the current collector does not reach a minimum or the resistance value does not reach a maximum during a given duration of the preheating process, generate a control signal for stopping the operation of the aerosol generating device.

Example Ex39: An aerosol generating device according to any of examples Ex35-Ex38, wherein the controller is configured to perform a preheating process in response to detecting an aerosol generating article containing a current collector.

Example Ex40: An aerosol generating device according to any of examples Ex35-Ex39, wherein the controller is configured to perform a preheating process in response to detecting a user input.

Example Ex41: An aerosol generating device according to any of examples Ex21-Ex40, further comprising a housing having a cavity configured to accommodate an aerosol generating article, wherein the aerosol generating article comprises an aerosol forming substrate and a current collector.

Example Ex42: An aerosol generating system comprising: an aerosol generating device according to any one of paragraphs 21-41; and an aerosol generating article, wherein the aerosol generating article comprises an aerosol forming substrate and a current collector.

Example Ex43: An aerosol generating system according to example Ex42, wherein the current collector comprises a first current collecting material and a second current collecting material, wherein the first current collecting material is located in physical contact with the second current collecting material.

Example Ex44: An aerosol generating system according to example Ex42 or Ex43, wherein the first current-receiving material has a first Curie temperature and the second current-receiving material has a second Curie temperature, wherein the second Curie temperature is lower than the first Curie temperature.

Example Ex45: An aerosol generating system according to example Ex44, wherein the second calibration temperature corresponds to the second Curie temperature of the second current-collecting material.

The examples will now be further described with reference to figures, where:

Fig. 1 shows a schematic cross-sectional view of an aerosol generating article;

Fig. 2A is a schematic cross-sectional view of an aerosol generating device for use with the aerosol generating article illustrated in Fig. 1;

Fig. 2B is a schematic cross-sectional view of an aerosol generating device in engagement with the aerosol generating article illustrated in Fig. 1;

Fig. 3 is a block diagram showing the aerosol generating induction heating device described in relation to Fig. 2;

Fig. 4 is a schematic diagram showing the electronic components of the induction heating device described in relation to Fig. 3;

Fig. 5 shows a schematic representation of the LC load circuit inductor of the induction heating device described in relation to Fig. 4;

Fig. 6 is a graph of direct current versus time illustrating remotely detectable current changes that occur when a current-collecting material undergoes a phase transition associated with its Curie point;

Fig. 7 shows the temperature profile of the current collector during operation of the aerosol generating device; and

Fig. 8 is a block diagram showing a method for controlling aerosol formation in the aerosol generating device shown in Fig. 2.

In Fig. 1, an article 100 generating an aerosol is illustrated. The article 100 generating an aerosol comprises four coaxially aligned elements: an aerosol-forming substrate 110, a support element 120, an aerosol-cooling element 130, and a mouthpiece 140. Each of these four elements is a substantially cylindrical element, and each of them has a substantially identical diameter. These four elements are arranged in series and surrounded by an outer wrapper 150 to form a cylindrical rod. An elongated current collector 160 is located in the aerosol-forming substrate 110 in contact with the aerosol-forming substrate 110. The current collector 160 has a length that is approximately the same as the length of the aerosol-forming substrate 110 and is located along the radially central axis of the aerosol-forming substrate 110.

Current collector 160 comprises at least two different materials. Current collector 160 has the shape of an elongated strip, preferably having a length of 12 mm and a width of 4 mm. Current collector 160 comprises at least two layers: a first layer of a first current-collecting material located in physical contact with a second layer of a second current-collecting material. Each of the first current-collecting material and the second current-collecting material may have a Curie temperature. In this case, the Curie temperature of the second current-collecting material is lower than the Curie temperature of the first current-collecting material. The first material may not have a Curie temperature. The first current-collecting material may be made of aluminum, iron, or stainless steel. The second current-collecting material may be made of nickel or a nickel alloy. Current collector 160 may be formed by electrolytic deposition of at least one section of the second current-collecting material onto a strip of the first current-collecting material. The current collector may be formed by applying a strip of the second current collector material to a strip of the first current collector material.

The aerosol generating article 100 has a near or mouthpiece end 170 that the user inserts into his mouth during use, and a distal end 180 located at the opposite end of the aerosol generating article 100 relative to the mouthpiece end 170. In the assembled state, the total length of the aerosol generating article 100 is preferably approximately 45 mm, and the diameter is approximately 7.2 mm.

In use, air is drawn by the user through the aerosol-generating article 100 from the distal end 180 to the mouth-facing end 170. The distal end 180 of the aerosol-generating article 100 can also be described as the upstream end of the aerosol-generating article 100, and the mouth-facing end 170 of the aerosol-generating article 100 can also be described as the downstream end of the aerosol-generating article 100. The elements of the aerosol-generating article 100 located between the mouthpiece end 170 and the distal end 180 may be described as being upstream of the mouthpiece end 170 or, alternatively, downstream of the distal end 180. The aerosol-forming substrate 110 is located at the distal or upstream end 180 of the aerosol-generating article 100.

The support element 120 is located immediately downstream of the aerosol-forming substrate 110 and abuts against the aerosol-forming substrate 110. The support element 120 may be a hollow cellulose acetate tube. The support element 120 positions the aerosol-forming substrate 110 at the extreme distal end 180 of the aerosol-generating article 100. The support element 120 also acts as a separator for separating the aerosol cooling element 130 of the aerosol-generating article 100 from the aerosol-forming substrate 110.

The aerosol cooling element 130 is located immediately downstream of the support element 120 and abuts against the support element 120. In use, volatiles released from the aerosol-forming substrate 110 pass along the aerosol cooling element 130 toward the mouthpiece end 170 of the aerosol-generating article 100. The volatiles can be cooled inside the aerosol cooling element 130 to form an aerosol that is inhaled by the user. The aerosol cooling element 130 may comprise a corrugated and assembled sheet of polylactic acid surrounded by a wrapper 190. The corrugated and assembled sheet of polylactic acid forms several longitudinal channels that extend along the length of the aerosol cooling element 130.

Mouthpiece 140 is located immediately downstream of aerosol cooling element 130 and is adjacent to aerosol cooling element 130. Mouthpiece 140 contains a traditional low-efficiency cellulose acetate filter.

To assemble the aerosol-generating article 100, the four elements 110, 120, 130, and 140 described above are aligned and tightly wrapped in an outer wrapper 150. The outer wrapper may be ordinary cigarette paper. The current collector 160 may be inserted into the aerosol-generating substrate 110 during the process used to form the aerosol-generating substrate 110, before assembling several elements to form a rod.

The aerosol-generating article 100 shown in Fig. 1 is intended to interact with an aerosol-generating device, such as the aerosol-generating device 200 shown in Fig. 2A, to produce an aerosol. The aerosol-generating device 200 comprises a body 210 having a cavity 220 configured to accommodate the aerosol-generating article 100. The aerosol-generating device 200 further comprises an induction heating device 230 configured to heat the aerosol-generating article 100 to produce an aerosol. Fig. 2B illustrates the aerosol-generating device 200 when the aerosol-generating article 100 is inserted into the cavity 220.

The induction heating device 230 is illustrated in block diagram form in Fig. 3. The induction heating device 230 comprises a DC power source 310 and a heating device 320 (also referred to as a power supply electronic circuit). The heating device comprises a controller 330, a DC-to-AC converter 340, a matching network 350, and an inductor 240.

The DC power source 310 is configured to supply DC power to the heating device 320. In particular, the DC power source 310 is configured to supply DC power voltage ( _VDC ) and DC current ( _IDC ) to the DC-to-AC converter 340. Preferably, the power source 310 is a battery, such as a lithium iron phosphate battery. Alternatively, the power source 310 may be another type of charge storage device, such as a capacitor. The power source 310 may require recharging. For example, the power source 310 may have a capacity sufficient to enable continuous aerosol generation for a period equal to approximately six minutes, or for a period multiple of six minutes. In another example, the power source 310 may have a capacity sufficient to enable a given number of puffs or individual activations of the heating device.

The DC-to-AC converter 340 is configured to supply the inductor 240 with high-frequency alternating current. In the context of this document, the term "high-frequency alternating current" means alternating current with a frequency of approximately 500 kilohertz to approximately 30 megahertz. The high-frequency alternating current may have a frequency of approximately 1 megahertz to approximately 30 megahertz, for example, from approximately 1 megahertz to approximately 10 megahertz, or, for example, from approximately 5 megahertz to approximately 8 megahertz.

Fig. 4 schematically shows the electrical components of the induction heating device 230, in particular the DC to AC converter 340. The DC to AC converter 340 preferably comprises a class E power amplifier. The class E power amplifier comprises a transistor switch 410 comprising a field effect transistor 420, for example a field effect transistor with a metal-oxide-semiconductor structure, a transistor switch power supply circuit, indicated by an arrow 430, for supplying a switching signal (gate-source voltage) to the field effect transistor 420, and an LC load circuit 440 comprising a shunt capacitor C1 and a series connection of a capacitor C2 and an inductor L2 corresponding to the inductor 240. In addition, a DC power supply 310 is shown, comprising a choke L1, for supplying a DC supply voltage V _DC , with a DC current I _DC , obtained from the DC power supply 310, during operation. The ohmic resistance R representing the total ohmic load 450, which is the sum of the ohmic resistance R of the inductor _coil L2 and the ohmic resistance R _{of the load} of the current collector 160, is shown in more detail in Fig. 5.

Although DC-to-AC converter 340 is shown as comprising a Class E power amplifier, it should be understood that DC-to-AC converter 340 may utilize any suitable circuit that converts DC to AC. For example, DC-to-AC converter 340 may comprise a Class D power amplifier comprising two transistor switches. As another example, DC-to-AC converter 340 may comprise a full-bridge inverting power amplifier with four switching transistors operating in pairs.

Returning to Fig. 3, inductor 240 can receive alternating current from DC-to-AC converter 340 through matching network 350 for optimal adaptation to the load, but matching network 350 is not essential. Matching network 350 can include a small matching transformer. Matching network 350 can improve the efficiency of power transfer between DC-to-AC converter 340 and inductor 240.

As shown in Fig. 2A, the inductor 240 is located near the distal portion 225 of the cavity 220 of the aerosol generating device 200. Accordingly, the high-frequency alternating current supplied to the inductor 240 during operation of the aerosol generating device 200 causes the inductor 240 to generate a high-frequency alternating magnetic field in the distal portion 225 of the aerosol generating device 200. The alternating magnetic field preferably has a frequency of 1 to 30 megahertz, preferably 2 to 10 megahertz, for example 5 to 7 megahertz. As can be seen in Fig. 2B, when the aerosol-generating article 100 is introduced into the cavity 200, the aerosol-forming substrate 110 of the aerosol-generating article 100 is located near the inductor 240, so that the susceptor 160 of the aerosol-generating article 100 is located within this alternating magnetic field. When the alternating magnetic field penetrates the susceptor 160, the alternating magnetic field causes the susceptor 160 to heat up. For example, eddy currents are generated in the susceptor 160, which heats up as a result. Additional heating is provided by magnetic hysteresis losses inside the susceptor 160. The heated susceptor 160 heats the aerosol-forming substrate 110 of the aerosol-generating article 100 to a sufficient temperature for the formation of an aerosol. The aerosol is drawn further downstream through the aerosol generating article 100 and inhaled by the user.

Controller 330 may be a microcontroller, preferably a programmable microcontroller. Controller 330 is programmed to regulate the power supply from DC source 310 to induction heating device 320 to control the temperature of susceptor 160.

Fig. 6 illustrates the relationship between the direct current I _DC drawn from the power source 310 over time as the temperature of the current collector 160 (indicated by the dotted line) increases. The direct current I _DC drawn from the power source 310 is measured at the input side of the DC/AC converter 340. For illustrative purposes, it can be assumed that the voltage V _DC of the power source 310 remains approximately constant. As the current collector 160 is inductively heated, the apparent resistance of the current collector 160 increases. This increase in resistance is observed as a decrease in the direct current I _DC drawn from the power source 310, which at a constant voltage decreases as the temperature of the current collector 160 increases. The high-frequency alternating magnetic field provided by the inductor 240 induces eddy currents in the immediate vicinity of the surface of the current collector, that is, an effect that is known as the skin effect. The resistance of the current collector 160 depends partly on the electrical resistance of the first current collector material, the specific resistance of the second current collector material, and partly on the depth of the surface layer in each material accessible to induced eddy currents, and the specific resistance, in turn, depends on the temperature. As the second current collector material reaches its Curie temperature, it loses its magnetic properties. This causes an increase in the surface layer accessible to eddy currents in the second current collector material, which causes a decrease in the apparent resistance of the current collector 160. The result is a temporary increase in the detected direct current I _DC ; when the layer depth of the second current collector material begins to increase, the resistance begins to fall. This is visible as a valley (local minimum) in Fig. 6. The current continues to increase until the maximum layer depth is reached, which coincides with the point at which the second current collector material lost its spontaneous magnetic properties. This point is called the Curie temperature and is visible as a rise (local maximum) in Fig. 6. At this point, the second current-collecting material has undergone a phase transition from a ferromagnetic or ferrimagnetic-magnetic state to a paramagnetic state. At this point, current collector 160 is at a known temperature (the Curie temperature, which is the internal temperature dependent on the specific material). If the inductor 240 continues to generate an alternating magnetic field (i.e., the power to the DC/AC converter 340 is not interrupted) after the Curie temperature has been reached, the eddy currents generated in the current collector 160 will collide with the resistance of the current collector 160, causing Joule heating in the current collector 160 to continue, and thus the resistance will increase again (the resistance will have a polynomial dependence on temperature, which for most metallic current collector materials can be approximated by a third-degree polynomial dependence for our purposes), and the current will again begin to drop as long as the inductor 240 continues to supply power to the current collector 160.

Thus, as can be seen from Fig. 6, the apparent resistance of the current collector 160 (and, accordingly, the current I _DC consumed from the power source 310) can change together with the temperature of the current collector 160 in a strictly constant ratio in certain ranges of the temperature of the current collector 160. The strictly constant ratio makes it possible to unambiguously determine the temperature of the current collector 160 based on the determination of the apparent resistance or apparent conductivity (1/R). This is due to the fact that each determined value of the apparent resistance is characteristic of only one single temperature value, therefore, there is no ambiguity in the ratio. The constant ratio of the temperature of the current collector 160 and the apparent resistance makes it possible to determine and control the temperature of the current collector 160 and, thus, to determine and control the temperature of the substrate 110 forming the aerosol. The apparent resistance of the current collector 160 can be remotely detected by monitoring at least the direct current I _DC drawn from the direct current power source 310.

At least the direct current I _DC consumed from the power source 310 is controlled by the controller 330. Preferably, both the direct current I _DC consumed from the power source 310 and the direct current supply voltage V _DC are controlled. The controller 330 regulates the supply of energy supplied to the heating device 320 based on the conductivity or resistance value, where the conductivity is defined as the ratio of the direct current I _DC to the direct current supply voltage V _DC and the resistance is defined as the ratio of the direct current supply voltage V _DC to the direct current I _DC . The heating device 320 may comprise a current sensor (not shown) for measuring the direct current I _DC . The heating device may further comprise a voltage sensor (not shown) for measuring the direct current supply voltage V _DC . The current sensor and the voltage sensor are located on the input side of the DC to AC converter 340. Direct current I _DC and optionally direct current supply voltage V _DC are fed through feedback channels to controller 330 to control further supply of alternating current P _AC to inductor 240.

The controller 330 can control the temperature of the current collector 160 by maintaining the measured conductivity value or the measured resistance value at a predetermined value corresponding to a predetermined operating temperature of the current collector 160. The controller 330 can use any suitable control loop to maintain the measured conductivity value or the measured resistance value at a predetermined value, for example, using a proportional-integral-derivative control loop.

In order to take advantage of the strictly unchanged relationship between the apparent resistance (or apparent conductivity) of the current collector 160 and the temperature of the current collector 160 during the user's operation of obtaining an aerosol, the conductivity or resistance value associated with the current collector and measured on the input side of the DC/AC converter 340 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 of the second current collector material (an elevation in the current graph in Fig. 6). The first calibration temperature is a temperature greater than or equal to the temperature of the current collector, at which the layer thickness of the second current collector material begins to increase (which leads to a temporary decrease in resistance). Thus, the first calibration temperature is a temperature greater than or equal to the temperature at the maximum permeability of the second current collector material. The first calibration temperature is at least 50 degrees Celsius lower than the second calibration temperature. At least the second calibration value can be determined by calibrating the current collector 160, as will be described in more detail below. The first calibration value and the second calibration value can be stored as calibration values in the memory of the controller 330.

Since conductivity (resistance) will have a polynomial dependence on temperature, conductivity (resistance) will behave nonlinearly as a function of temperature. However, the first and second calibration values are selected such that this dependence can be approximated as linear between the first and second calibration values, since the difference between the first and second calibration values is small, and the first and second calibration values are at the upper end of the operating temperature range. Therefore, to adjust the temperature to the specified operating temperature, conductivity is adjusted according to the first calibration value and the second calibration value using linear equations. For example, if the first and second calibration values are conductivity values, the target conductivity value corresponding to the target operating temperature can be specified using:

Where is the difference between the first conductivity value and the second conductivity value, and represents a percentage .

The controller 330 can control the power supply to the heating device 320 by adjusting the duty cycle of the switching transistor 410 of the DC/AC converter 340. For example, during heating, the DC/AC converter 340 continuously generates an alternating current that heats the current collector 160, and simultaneously, the DC supply voltage _VDC and _{the DC} current IDC can be measured preferably every millisecond for 100 milliseconds. If the conductivity is controlled by the controller 330, then when the conductivity reaches or exceeds the value corresponding to the target operating temperature, the duty cycle of the switching transistor 410 is reduced. If the resistance is controlled by the controller 330, then when the resistance reaches or falls below the value corresponding to the target operating temperature, the duty cycle of the switching transistor 410 is reduced. For example, the duty cycle of the switching transistor 410 can be reduced to approximately 9%. In other words, switching transistor 410 can be switched to a mode in which it generates pulses only every 10 milliseconds for 1 millisecond. During this 1 millisecond, in the on-state (conducting state), the DC supply voltage _VDC and _DC current IDC are measured, and conductance is determined. When conductance decreases (or resistance increases), indicating that the temperature of current collector 160 is below the target operating temperature, a pulse train at the selected excitation frequency for the system is again applied to the gate of transistor 410.

Power may be supplied by controller 330 to inductor 240 in the form of a series of sequential electric current pulses. Specifically, power may be supplied to inductor 240 via a series of pulses, each separated by a time interval. A series of sequential pulses may comprise two or more heating pulses and one or more probe pulses between successive heating pulses. The heating pulses have an intensity sufficient to heat current collector 160. The probe pulses are isolated power pulses of an intensity sufficient not to heat current collector 160, but rather to obtain feedback on the conductivity value or resistance value, and then on the change (decrease) in current collector temperature. The controller 330 can control the power supply by controlling the duration of the time interval between successive power supply heating pulses supplied by the DC power supply to the inductor 240. Additionally or alternatively, the controller 330 can control the power supply by controlling the duration (in other words, the length) of each of the successive power supply heating pulses supplied by the DC power supply to the inductor 240.

The controller 330 is programmed to perform a calibration process to obtain calibration values at which the conductivity is measured at known temperatures of the current collector 160. The known temperatures of the current collector may be a first calibration temperature corresponding to a first calibration value, and a second calibration temperature corresponding to a second calibration value. Preferably, the calibration process is performed each time the user operates the aerosol-generating device 200, for example, each time the user inserts the aerosol-generating article 100 into the aerosol-generating device 200.

During the calibration process, the controller 330 controls the DC/AC converter 340 to continuously or continuously supply power to the inductor 240 to heat the current collector 160. The controller 330 monitors the conductivity or resistance associated with the current collector 160 by measuring the current I _DC consumed by the power supply and, optionally, the voltage V _DC of the power supply. As discussed above with respect to Fig. 6, as the current collector 160 heats up, the measured current decreases until the first critical point is reached and the current begins to increase. This first critical point corresponds to the local minimum conductivity value (local maximum resistance value). The controller 330 can record the local minimum conductivity value (or local maximum resistance) as the first calibration value. The controller can record the conductivity or resistance value at a predetermined time after reaching the minimum current as the first calibration value. The conductivity or resistance can be determined based on the measured current I _DC and the measured voltage V _DC . Alternatively, it can be assumed that the voltage V _DC of the power supply, which is a known property of the power source 310, is approximately constant. The temperature of the current collector 160 at the first calibration value is called the first calibration temperature. Preferably, the first calibration temperature is from 150 degrees Celsius to 350 degrees Celsius. More preferably, when the aerosol-forming substrate 110 contains tobacco, the first calibration temperature is 320 degrees Celsius. The first calibration temperature is at least 50 degrees Celsius lower than the second calibration temperature.

As controller 330 continues to control the power supplied by DC/AC converter 340 to inductor 240, the measured current increases until a second critical point is reached and the maximum current is observed (corresponding to the Curie temperature of the second current-sensing material) before the measured current begins to decrease. This critical point corresponds to the local maximum conductivity value (local minimum resistance value). Controller 330 records the local maximum conductivity value (or local minimum resistance value) as a second calibration value. The temperature of current-sensing material 160 at the second calibration value is called the second calibration temperature. Preferably, the second calibration temperature is between 200 degrees Celsius and 400 degrees Celsius. When the maximum value is detected, the controller 330 controls the DC-to-AC converter 340 to interrupt the power supply to the inductor 240, which results in a decrease in the temperature in the current collector 160 and a corresponding decrease in conductivity.

Due to the shape of the graph, this process of continuously heating the current collector 160 to obtain the first calibration value and the second calibration value can be repeated at least once. After interrupting the power supply to the inductor 240, the controller 330 continues to monitor (regulate) the conductivity (or resistance) until a third critical point corresponding to the second minimum conductivity value (the second maximum resistance value) is observed. When the third critical point is detected, the controller 330 controls the DC/AC converter 340 to continuously supply power to the inductor 240 until a fourth critical point corresponding to the second maximum conductivity value (the second minimum resistance value) is detected. The controller 330 stores the conductivity value or the resistance value at the third critical point or immediately after it as the first calibration value and the conductivity value or the resistance value at the fourth current critical point as the second calibration value. Repeated measurement of critical points corresponding to the minimum and maximum measured current significantly improves subsequent temperature control during user operation of the aerosol-generating device. Preferably, controller 330 regulates power based on the conductivity or resistance values obtained from the second maximum and second minimum, which is more reliable because the heat will have more time to distribute within the aerosol-generating substrate 110 and the current collector 160.

To further improve the reliability of the calibration process, controller 310 can be additionally programmed to perform a preheating process prior to the calibration process. For example, if aerosol-forming substrate 110 is particularly dry or under similar conditions, calibration can be performed before heat has dissipated within the aerosol-forming substrate 110, reducing the reliability of the calibration values. If aerosol-forming substrate 110 was wet, susceptor 160 requires more time to reach its minimum temperature (due to the water content of substrate 110).

To perform the preheating process, the controller 330 is configured to continuously supply power to the inductor 240. As described above, the current begins to decrease with an increase in the temperature of the current collector 160 until a minimum value is reached. At this stage, the controller 330 is configured to wait for a predetermined period of time to allow the current collector 160 to cool before continuing heating. Therefore, the controller 330 controls the DC-to-AC converter 340 to interrupt the supply of power to the inductor 240. After the predetermined period of time has elapsed, the controller 330 controls the DC-to-AC converter 340 to provide power until the minimum value is reached. At this point, the controller controls the DC-to-AC converter 340 to again interrupt the supply of power to the inductor 240. The controller 330 again waits for the same predetermined period of time to allow the current collector 160 to cool before continuing heating. This heating and cooling of the current collector 160 is repeated for a predetermined preheating period. The predetermined preheating period is preferably 11 seconds. The predetermined total preheating period, followed by the calibration process, is preferably 20 seconds.

If the aerosol-forming substrate 110 is dry, the first minimum value of the preheating process is reached within a predetermined period of time, and the power interruption will be repeated until the end of the predetermined period. If the aerosol-forming substrate 110 is wet, the first minimum value of the preheating process will be reached by the end of the predetermined period of time. Therefore, performing the preheating process for a predetermined duration ensures that, regardless of the physical state of the substrate 110, this time is sufficient for the substrate 110 to reach the minimum temperature, be ready for continuous power supply, and reach the first maximum value. This allows calibration to be performed as early as possible, yet without the risk of the substrate 110 not reaching the minimum point early.

Furthermore, the aerosol-generating article 100 can be designed such that the minimum value is always reached within a predetermined duration of the preheating process. If the minimum value is not reached within a predetermined duration of the preheating process, this may indicate that the aerosol-generating article 100, containing the aerosol-forming substrate 110, is not suitable for use with the aerosol-generating device 200. For example, the aerosol-generating article 100 may contain an aerosol-forming substrate 110 that is different from or of lower quality than the aerosol-forming substrate 100 intended for use with the aerosol-generating device 200. As another example, the aerosol-generating article 100 may not be configured for use with the heating device 320, for example, if the aerosol-generating article 100 and the aerosol-generating device 200 are manufactured by different manufacturers. Thus, the controller 330 may be configured to generate a control signal to terminate the operation of the aerosol-generating device 200.

The preheating process may be performed in response to receiving user input, such as user activation of the aerosol-generating device 200. Additionally or alternatively, the controller 330 may be configured to detect the presence of the aerosol-generating article 100 in the aerosol-generating device 200, and the preheating process may be performed in response to detecting the presence of the aerosol-generating article 100 within the cavity 220 of the aerosol-generating device 200.

Fig. 7 shows a graph of conductivity versus time, showing the heating profile of the current collector 160. The graph illustrates two sequential heating phases: a first heating phase 710, including the preheating process 710A and the calibration process 710B described above, and a second heating phase 720, corresponding to the user's operation with the aerosol generating device 200 to generate an aerosol. Although Fig. 7 illustrates a graph of conductivity versus time, it should be understood that the controller 330 can be configured to control the heating of the current collector during the first heating phase 710 and the second heating phase 720 based on the measured resistance or current, as described above.

In addition, although the methods for controlling the heating of the current collector during the first heating phase 710 and the second heating phase 720 have been described above based on a determined conductivity value or a determined resistance value associated with the current collector, it should be understood that the methods described above can be performed based on a current value measured at the input of the DC to AC converter 340.

As can be seen from Fig. 7, the second heating phase 720 includes a plurality of conductivity steps corresponding to a plurality of temperature steps from the first operating temperature of the current collector 160 to the second operating temperature of the current collector 160. The first operating temperature of the current collector is the minimum temperature at which the aerosol-forming substrate will form an aerosol in a sufficient volume and quantity for a satisfactory sensation when inhaled by the user. The second operating temperature of the current collector is the temperature at the maximum temperature at which it is desirable to heat the aerosol-forming substrate so that the user inhales the aerosol. The first operating temperature of the current collector 160 is greater than or equal to the first calibration temperature of the current collector 160 at the minimum point of the current graph shown in Fig. 6. The first operating temperature can be from 150 degrees Celsius to 330 degrees Celsius. The second operating temperature of the current collector is less than or equal to the second calibration temperature of the current collector 160 at the Curie temperature of the second material of the current collector. The second operating temperature may range from 200 degrees Celsius to 400 degrees Celsius. The difference between the first operating temperature and the second operating temperature is at least 50 degrees Celsius. The first operating temperature of the susceptor is the temperature at which the aerosol-forming substrate 110 forms an aerosol, such that an aerosol is formed during each temperature step.

It should be understood that the number of temperature stages illustrated in Fig. 7 is exemplary, and that the second heating phase 720 includes at least three successive temperature stages, preferably from two to fourteen temperature stages, most preferably from three to eight temperature stages. Each temperature stage may have a predetermined duration. Preferably, the duration of the first temperature stage is longer than the duration of subsequent temperature stages. The duration of each temperature stage is preferably more than 10 seconds, preferably from 30 to 200 seconds, more preferably from 40 to 160 seconds. The duration of each temperature stage may correspond to a predetermined number of user puffs. Preferably, the first temperature stage corresponds to four user puffs, and each subsequent temperature stage corresponds to one user puff.

During each temperature step, the temperature of the current collector 160 is maintained within the target operating temperature corresponding to the respective temperature step. Thus, during each temperature step, the controller 330 controls the power supply to the heating device 320 such that the conductivity is maintained within the value corresponding to the target operating temperature of the respective temperature step, as described above. The target conductivity values for each temperature step can be stored in the memory of the controller 330.

As an example, the second heating phase 720 may comprise five temperature stages: a first temperature stage having a duration of 160 seconds and a target conductivity value , the second temperature step, which has a duration of 40 seconds and a target conductivity value , the third temperature stage, which has a duration of 40 seconds and a target conductivity value , the fourth temperature stage, which has a duration of 40 seconds and a target conductivity value, and the fifth temperature stage, which has a duration of 85 seconds and a target conductivity value These temperature steps can correspond to temperatures of 330 degrees Celsius, 340 degrees Celsius, 345 degrees Celsius, 355 degrees Celsius and 380 degrees Celsius.

Fig. 8 shows a flow chart of a method 800 for controlling the production of an aerosol in an aerosol generating device 200. As described above, the controller 330 can be programmed to perform the method 800.

The method begins with step 810, in which controller 330 detects user interaction with aerosol-generating device 200 to generate an aerosol. Detecting user interaction with aerosol-generating device 200 may include detecting user input, such as user activation of aerosol-generating device 200. Additionally or alternatively, detecting user interaction with aerosol-generating device 200 may include detecting that aerosol-generating article 100 has been inserted into aerosol-generating device 200.

In response to detecting user activity at step 810, the controller 330 may be configured to perform the optional pre-heating process described above. At the end of the predetermined duration of the pre-heating process, the controller 330 performs the calibration process (step 820), as described above. Alternatively, the controller 330 may be configured to proceed to step 820 in response to detecting user activity at step 810. After completing the calibration process, the controller 330 performs a second heating phase, during which an aerosol is produced at step 840.

For the purposes of the present description and the appended claims, except where otherwise indicated, all numbers expressing quantities, amounts, percentages, etc., shall be understood as modified in all instances by the term "about." Also, all ranges include the disclosed maximum and minimum points and include any intermediate ranges therebetween, which may or may not be specifically listed herein. In this context, the number A may be considered to include numerical values that are within the common standard error for measuring the property that the number "A" modifies. The number A, in some instances, when used in the appended claims, may deviate by the percentages listed above, provided that the amount by which A deviates does not materially affect the fundamental and novel characteristic(s) of the claimed invention. Also, all ranges include the disclosed maximum and minimum points and include any intermediate ranges therebetween, which may or may not be specifically listed herein.

Claims (49)

1. A method for regulating the production of an aerosol in an aerosol generating device, wherein the aerosol generating device comprises a heating device and a power source for supplying power to the heating device, and wherein the method includes: performing a calibration process for measuring calibration values associated with the current collector, wherein the heating device is configured to inductively heat the current collector based on the calibration values, and wherein the calibration process includes the following steps: i) adjusting the power supplied to the heating device to ensure an increase in the temperature of the current collector; ii) monitoring the conductivity value or the resistance value associated with the current collector; iii) interrupting the supply of power to the heating device when the conductivity value reaches a maximum, or interrupting the supply of power to the heating device when the resistance value reaches a minimum, wherein the conductivity value at maximum conductivity or the resistance value at minimum resistance is a second calibration value associated with the susceptor; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a minimum, or monitoring the resistance value associated with the current collector until the resistance value reaches a maximum, wherein the conductivity value at minimum conductivity or the resistance value at maximum resistance is the first calibration value associated with the current collector, wherein the calibration process is performed in response to the detection of a control signal associated with the end of the preheating process, wherein the preheating process has a specified duration. 2. The method according to claim 1, characterized in that the current collector contains a first material having a first Curie temperature and a second material having a second Curie temperature, wherein the second Curie temperature is lower than the first Curie temperature, and wherein the second calibration temperature of the current collector, associated with the second calibration value of conductivity, corresponds to the second Curie temperature of the second material. 3. The method according to paragraph 1 or 2, characterized in that the calibration process is performed while the user is working with the aerosol generating device. 4. The method according to any one of paragraphs 1-3, characterized in that it further includes regulating the power supplied to the induction heating device to maintain the conductivity value associated with the current collector between the first calibration value and the second calibration value. 5. The method of claim 4, wherein regulating the power supplied to the induction heating device includes regulating the power supplied to the induction heating device to provide a stepwise increase in the conductivity value associated with the current collector from a first operating conductivity value to a second operating conductivity value, wherein the temperature of the current collector associated with the first operating conductivity value is sufficient for the aerosol formation by the aerosol-forming substrate. 6. The method according to any one of paragraphs 1-3, characterized in that it further includes regulating the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the first calibration value and the second calibration value. 7. The method of claim 6, wherein regulating the power supplied to the induction heating device includes regulating the power supplied to the induction heating device to provide a stepwise decrease in the resistance value associated with the current collector from a first operating resistance value to a second operating resistance value, wherein the temperature of the current collector associated with the first operating resistance value is sufficient for the aerosol formation by the aerosol-forming substrate. 8. The method according to paragraph 1, characterized in that the preheating process includes the following steps: i) adjusting the power supplied to the induction heating device to ensure an increase in the temperature of the susceptor; ii) monitoring the conductivity value or the resistance value associated with the current collector; and iii) interrupting the power supply to the induction heating device when the conductivity value reaches a minimum or when the resistance value reaches a maximum. 9. The method according to claim 8, characterized in that it further comprises, if the conductivity value reaches a minimum or if the resistance value reaches a maximum before the end of the specified duration of the preheating process, repeating steps i) to iii) of the preheating process until the end of the specified duration of the preheating process. 10. The method according to any one of claims 1 to 8, characterized in that it further comprises, if the conductivity value does not reach a minimum or if the resistance value does not reach a maximum during a given duration of the preheating process, generating a control signal to stop the operation of the aerosol generating device. 11. An aerosol generating device comprising: a power supply for supplying DC power voltage and DC current; and an electronic power supply circuit connected to a power source, wherein the electronic power supply circuit comprises: a DC to AC converter; an inductor connected to the DC to AC converter for generating an alternating magnetic field when excited by alternating current from the DC to AC converter, wherein the inductor is configured to be inductively connected to a current collector, wherein the current collector is configured to heat an aerosol-forming substrate; and a controller configured to: performing a calibration process for measuring calibration values associated with a current collector, wherein the electronic circuit of the power supply is configured to inductively heat the current collector based on the calibration values, and wherein the calibration process includes the following steps: i) regulation of the power supplied to the inductor to ensure an increase in the temperature of the current collector; ii) monitoring the conductivity value or the resistance value associated with the current collector; iii) interrupting the supply to the inductor when the conductance value reaches a maximum, or interrupting the supply to the inductor when the resistance value reaches a minimum, wherein the conductance value at maximum conductance or the resistance value at minimum resistance is a second calibration value associated with the current collector; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a minimum, or monitoring the resistance value associated with the current collector until the resistance value reaches a maximum, wherein the conductivity value at minimum conductivity or the resistance value at maximum resistance represents the first calibration conductivity value associated with the current collector, wherein the controller is configured to perform a calibration process in response to detecting a control signal associated with the end of the preheating process, wherein the preheating process has a specified duration. 12. The aerosol generating device according to claim 11, characterized in that the second operating temperature of the current collector, associated with the second conductivity calibration value, corresponds to the Curie temperature of the current collector material. 13. An aerosol generating device according to claim 11 or 12, characterized in that the controller is further configured to regulate the power supplied to the inductor to maintain the conductivity value associated with the current collector between the first calibration value and the second calibration value. 14. An aerosol generating device according to claim 11 or 12, characterized in that the controller is further configured to regulate the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the first calibration value and the second calibration value. 15. An aerosol generating device according to paragraph 11 or 12, characterized in that the calibration process further includes: v) when the conductivity value reaches a minimum or when the resistance value reaches a maximum, adjusting the power supplied to the heating device to ensure an increase in the temperature of the current collector; vi) monitoring the conductivity value or the resistance value associated with the current collector; vii) interrupting the supply of power to the inductor when the conductance value reaches a second maximum or when the resistance value reaches a second minimum, wherein the conductance value at the second maximum is a fourth calibration value associated with the current collector or the resistance value at the second maximum is a fourth calibration value associated with the current collector; and iv) monitoring the conductivity value associated with the current collector until the conductivity value reaches a second minimum, wherein the conductivity value at the second minimum is a third calibration value associated with the current collector, or monitoring the resistance value associated with the current collector until the resistance value reaches a second maximum, wherein the resistance value at the second maximum is a third calibration value associated with the current collector. 16. The aerosol generating device according to claim 15, characterized in that the controller is further configured to regulate the power supplied to the inductor to maintain the conductivity value associated with the current collector between the third calibration value and the fourth calibration value. 17. The aerosol generating device of claim 15, wherein the controller is further configured to regulate the power supplied to the induction heating device to maintain the resistance value associated with the current collector between the third calibration value and the fourth calibration value. 18. An aerosol generating device according to any one of paragraphs 11-17, characterized in that the controller is configured to perform a calibration process in response to detecting an aerosol generating article containing a current collector. 19. An aerosol generating device according to any one of paragraphs 11-17, characterized in that the controller is configured to perform a calibration process in response to detecting user input. 20. The aerosol generating device according to claim 11, characterized in that the controller is additionally configured to perform a preheating process, wherein the preheating process includes the following steps: i) regulation of the power supplied to the inductor to ensure an increase in the temperature of the current collector; ii) monitoring the conductivity value or the resistance value associated with the current collector; and iii) interrupting the power supply to the inductor when the conductivity value reaches a minimum or when the resistance value reaches a maximum. 21. The aerosol generating device according to claim 20, characterized in that the controller is configured to, if the conductivity value reaches a minimum or the resistance value reaches a maximum before the end of the specified duration of the preheating process, repeat steps i)-iii) of the preheating process until the end of the specified duration of the preheating process. 22. An aerosol generating device according to claim 20 or 21, characterized in that the controller is configured to, if the conductivity value of the current collector does not reach a minimum or the resistance value does not reach a maximum during a specified duration of the preheating process, generate a control signal to stop the operation of the aerosol generating device. 23. An aerosol generating device according to any one of paragraphs 11-22, characterized in that it further comprises a housing having a cavity configured to accommodate an aerosol generating article. 24. An aerosol generating device according to any one of paragraphs 11-22, characterized in that it is configured to accommodate an aerosol generating article, wherein the aerosol generating article comprises a current collector and an aerosol forming substrate, and with the capability of performing a preheating process in response to detection of the aerosol generating article. 25. An aerosol generating system comprising: an aerosol generating device according to any one of paragraphs 11-23; and an aerosol generating article, wherein the aerosol generating article comprises an aerosol forming substrate and a current collector.