Aerosol generation system with adaptive power control and method for producing aerosols - Patents.com

Abstract

An aerosol generating system (10) comprising an air inlet (28a) and an air outlet (28b), an airflow passage extending between the air inlet and the air outlet, and a heating element (30) for heating an aerosol-forming substrate (26). A sensor assembly (50) is in communication with the airflow passage, the sensor assembly configured to measure a pressure or flow rate within the airflow passage. A controller (60) is configured to detect the start of a puff, read the pressure or flow rate measured by the sensor assembly, and control the supply of power to the heating element in a first mode in response to the start of the puff and in dependence on both the time since the start of the puff and the pressure or flow rate read by the controller after the start of the puff.

Description

[Technical field]

[0001] The present invention relates to an aerosol generating system and a method for controlling aerosol generation, and in particular to the control of power in an aerosol generating system in which a user draws on the system to draw aerosol from the system, and to a method for controlling the supply of power in such a system. [Background technology]

[0002] In many aerosol generation systems for generating an aerosol for a user to inhale, an electrically operated heating element is used to heat an aerosol-forming substrate to generate an aerosol. Such aerosol generation systems include electronic cigarettes or heated tobacco systems that generate aerosols on demand for inhalation purposes. On-demand aerosol generation is typically initiated by a user inhaling the aerosol generation system. When the user inhales, air is drawn through the aerosol generation system and an aerosol is delivered to the user.

[0003] Users of this type of aerosol generating system may be past or current users of traditional lit-end cigarettes. In traditional lit-end cigarettes, increasing the user's puff intensity on the cigarette increases aerosol generation. However, in many electrically heated aerosol generating systems, increasing puff intensity does not increase aerosol generation proportionately. Increasing puff intensity increases airflow through the system, which cools the heater and reduces aerosol generation. However, increasing airflow also increases aerosol extraction from the system by entraining more aerosol droplets in the airflow. The exact relationship between puff intensity and aerosol volume can be complex and depends on the design of the system.

[0004] Different users may exhibit different puff behaviors when using an aerosol generating system. Also, a single user may exhibit different puff behaviors at different times. A puff behavior may be characterized by a combination of puff strength or pressure and puff duration. As a result of the relationship between puff strength and aerosol volume, an aerosol generating system set up to provide a satisfactory experience for one puff behavior may not provide a satisfactory experience for other puff behaviors.

[0005] It is therefore desirable to provide an aerosol generation system and method that mimics the aerosol delivery experience of a traditional filled-end cigarette in terms of aerosol volume, and is adapted to suit the puffing behavior of different users at different times, or different puffing behaviors of a single user. Summary of the Invention

[0006] In a first aspect of the present disclosure, an aerosol generation system is provided. The aerosol generation system may comprise an air inlet and an air outlet, an airflow passage extending between the air inlet and the air outlet, a heating element for heating an aerosol-forming substrate, and a sensor assembly in communication with the airflow passage, the sensor assembly configured to measure a pressure or flow rate within the airflow passage. The aerosol generation system may comprise a controller configured to read the pressure or flow rate measured by the sensor assembly, detect the start of a puff, and control the supply of power to the heating element in a first mode in response to the start of a puff. Preferably, the controller is configured to detect the start of a puff and the end of a puff, read the pressure or flow rate measured by the sensor assembly, and control the supply of power to the heating element in a first mode in response to the start of a puff and before the end of a puff. The controller may control the supply of power to the heating element in the first mode depending on both the time since the start of a puff and the pressure or flow rate read by the controller after the start of a puff. Preferably, the controller controls the supply of power to the heating element in the first mode and the controller determines the amount of power to supply to the heating element in the first mode at regular time intervals, the amount of power depending on both the time since the start of a puff and the pressure or flow rate read by the controller at each regular time interval.

[0007] Advantageously, this allows for adaptability of aerosol generation to better accommodate different puff behaviors, which in turn can better mimic the aerosol delivery experience of a user of a traditional lit-end cigarette, regardless of the different puff behaviors.

[0008] Preferably, the controller is further configured to read the pressure or flow rate from the sensor assembly in the first mode at regular time intervals. Advantageously, this allows regular adjustment of the supply of power to the heating element in response to pressure changes during a puff. The duration of the regular time intervals may be between 1 ms and 1000 ms. Preferably, the duration of the regular time intervals is between 2 ms and 500 ms, more preferably, the duration of the regular time intervals is between 5 ms and 250 ms, even more preferably, the duration of the regular time intervals is between 10 ms and 100 ms, even more preferably, the duration of the regular time intervals is between 20 ms and 60 ms, even more preferably, the duration of the regular time intervals is substantially equal to 40 ms.

[0009] The controller may include a computer readable memory storing a look-up table. The look-up table may include a plurality of power values. Each power value may correspond to a pressure range or flow rate range, and a time range since the beginning of a puff. The controller may further be configured to control the supply of power to the heating element in the first mode using the look-up table. Advantageously, such a look-up table may provide an aerosol generation adapted to the puffing behavior of the user. The time ranges may be of equal length. The time ranges may be between 0 ms and 2000 ms. Preferably, the length of the time ranges may be between 10 ms and 1500 ms. More preferably, the length of the time ranges may be between 50 ms and 1200 ms. Even more preferably, the length of the time ranges may be between 200 ms and 1000 ms. Even more preferably, the length of the time ranges may be between 600 ms and 800 ms. The time ranges may be of different lengths. This may mean that the time ranges best fit the typical pressure changes during a puff. The number of time ranges in the look-up table may be between 2 and 1000. The number of time ranges in the lookup table is preferably 2-100, more preferably 2-50, and even more preferably 2-20. The number of time ranges in the lookup table is even more preferably 2-10, more preferably 4-8, and even more preferably 5-7. In aspects of the present disclosure where pressure ranges or flow rates are used in the lookup table, the pressure ranges or flow rate ranges may be substantially equal in size. Alternatively, the pressure ranges or flow rate ranges may be different in size. This may mean that the pressure ranges or flow rate ranges are better adapted to typical changes in pressure during a puff. The number of pressure ranges or flow rate ranges in the lookup table may be 2-1000, preferably 2-100, more preferably 2-50, even more preferably 2-20, even more preferably 2-15, even more preferably 4-10, and most preferably 7-9.

[0010] The supply of power to the heating element in the first mode may depend on the difference between a reference pressure or flow rate and a pressure or flow rate read by the controller. The controller may detect the start of a puff when the difference between the reference pressure or flow rate and the pressure or flow rate read by the controller exceeds a first threshold pressure or flow rate. Advantageously, this ensures accurate detection of a puff and eliminates false detection of a puff due to small changes in ambient pressure. The first threshold pressure or flow rate may be predetermined. The first threshold pressure or flow rate may be stored in a computer readable memory. The first threshold pressure or flow rate may be calculated as a percentage or as a multiple of the reference pressure or flow rate.

[0011] The reference pressure or flow rate is preferably calculated by the controller as a rolling average of the integer number of pressure or flow rate values ​​read by the controller prior to detection of the start of a puff. Advantageously, this ensures that adequate power is supplied to the heating element regardless of changes in ambient pressure or the ambient pressure at which the system is used. Furthermore, this ensures that adequate power is supplied to the heating element even if there is a zero point or systematic error in the pressure read by the controller from the sensor assembly.

[0012] Preferably, the controller is further configured to control the supply of power to the heating element in the second mode, and the supply of power to the heating element in the second mode is independent of at least one of the measured time since the start of the puff and the pressure or flow rate read by the controller. Advantageously, this can ensure consistency in aerosol generation. Additionally or alternatively, this can act to balance the thermal inertia of the system. The supply of power to the heating element in the second mode may be independent of both the measured time since the start of the puff and the pressure or flow rate read by the controller. In the second mode, the power supplied to the heating element may be constant for the duration of the puff.

[0013] The controller may be further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The controller may be further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative puff time since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The controller may be further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The controller may further be configured to control the supply of power to the heating element in either the first mode or the second mode depending on a combination of at least two of the cumulative energy supplied to the heating element, the cumulative puff time, and the number of puffs since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element cools down to ambient temperature after at least one puff. The controller may be configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element within a particular time interval before the start of a puff. The controller may be configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative heating time of the heating element within a particular time interval before the start of a puff. Advantageously, any of these control strategies may be utilized to increase the overall power delivery to the heating element for the first few puffs to warm up the system.

[0014] The aerosol generating system preferably comprises an aerosol generating device. The aerosol generating device may comprise a receptacle configured to receive an aerosol generating article or cartridge containing an aerosol-forming substrate. The aerosol generating article or cartridge may be coupled to and decoupled from the aerosol generating device.

[0015] The controller may further be configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since the aerosol-generating article or cartridge was coupled to the aerosol generating device. The controller may be configured to control the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time since the aerosol-generating article or cartridge was coupled to the aerosol generating device. Any of these control strategies may be utilized to increase the overall power delivery for the first few puffs to warm up the system.

[0016] The heating element may be a resistive heating element. The resistive heating element may take the form of a mesh, array or woven fabric of conductive filaments. The aerosol-generating article containing the aerosol-forming substrate may supply the aerosol-forming liquid to the mesh.

[0017] The controller may further be configured to detect a malfunction in the heating element, such as when insufficient aerosol-forming liquid is supplied to the heating element.

[0018] The controller may be configured to determine the maximum electrical resistance of the heating element during each puff, calculate a rolling average of the maximum electrical resistance of the heating element during n previous heating cycles, where n is an integer greater than 1, compare the electrical resistance of the heating element to the calculated rolling average, and determine a malfunction when the electrical resistance is greater than the rolling average by a resistance threshold, where the resistance threshold is stored in a computer readable memory. The controller may be configured to determine a first or second derivative of the electrical resistance with respect to time and determine a malfunction when the first or second derivative is greater than or equal to a first or second derivative threshold, where the first or second derivative threshold is stored in a computer readable memory. For either configuration, the resistance threshold, or the first or second derivative threshold, may depend on whether the supply of power to the heating element is controlled in a first mode or a second mode. Preferably, the resistance threshold, or the first or second derivative threshold, depends on the power supplied to the heating element. The resistance threshold, or the first derivative value or the second derivative value threshold may be calculated for each of the power values ​​of the plurality of power values ​​stored in the computer readable memory. The resistance threshold, or the first derivative value or the second derivative value threshold corresponding to each of the power values ​​of the plurality of power values ​​stored in the computer readable memory may be stored in the computer readable memory. Advantageously, such threshold adjustment adjusts the sensitivity to malfunctions in the heating element to the power delivered to the mesh over time and to the pressure or flow rate, reducing the generation of potentially harmful components in the aerosol. The controller may determine malfunctions when the resistance threshold, or the first derivative value or the second derivative value threshold is exceeded during two consecutive puffs by the user. In this case, the resistance threshold, or the first derivative value or the second derivative value threshold may be adjusted after the resistance threshold, or the first derivative value or the second derivative value threshold is exceeded during a puff by the user.

[0019] In a second aspect of the disclosure, a method of generating an aerosol in an aerosol generating system is provided. The system may include an airflow passage extending between an air inlet and an air outlet, a heating element for heating an aerosol-forming substrate, a sensor assembly in communication with the airflow passage, and a controller including a computer readable memory. The method may include, in a first mode, detecting the start of a puff, reading an output from the sensor assembly to determine a pressure or flow rate in the airflow passage, and providing power to the heating element depending on both the time after the start of the puff and the pressure or flow rate in the airflow passage.

[0020] Preferably, in the first mode, the output from the sensor assembly is read at regular time intervals.

[0021] In a first mode, the supply of power to the heating element may depend on the difference between a reference pressure or flow rate and the pressure or flow rate in the airflow passage.

[0022] The method may further include, in the first mode, selecting a power value from a look-up table stored in the computer-readable memory based on the pressure or flow rate in the airflow passage and the time since the start of the puff. The look-up table may include a plurality of power values, each power value corresponding to a range of pressures or flow rates and a range of times since the start of the puff. The method may include providing power to the heating element based on the selected power value.

[0023] The method may include a controller reading an output from the sensor assembly to determine a pressure or flow rate in the airflow passage. The method may include detecting the onset of a puff when a difference between a baseline pressure or baseline flow rate and the pressure or flow rate in the airflow passage exceeds a first threshold pressure or first threshold flow rate. The baseline pressure or baseline flow rate may be calculated by the controller as a rolling average of an integer number of pressure or flow values ​​in the airflow passage prior to detection of the onset of a puff.

[0024] The method may include controlling the supply of power to the heating element in a second mode. The supply of power to the heating element in the second mode may be independent of at least one of a measured time since the start of the puff and a pressure or a flow rate in the airflow passage. In the second mode, the power supplied to the heating element may be constant for the duration of the puff.

[0025] The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the number of puffs since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the cumulative puff time since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the cumulative energy supplied to the heating element since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on a combination of at least two of the cumulative energy supplied to the heating element, the cumulative puff time, and the number of puffs since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The method may include controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element within a specified time interval before the start of a puff. The method may include controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative heating time of the heating element within a specified time interval before the start of a puff.

[0026] The aerosol generating system may comprise an aerosol generating device. The aerosol generating device may comprise a receptacle configured to receive an aerosol generating article or cartridge containing an aerosol-forming substrate. The aerosol generating article or cartridge may be coupled to and decoupled from the aerosol generating device. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the number of puffs since the aerosol generating article or cartridge was coupled to the aerosol generating device. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the accumulated puff time since the aerosol generating article or cartridge was coupled to the aerosol generating device.

[0027] The method may include detecting a malfunction in the heating element, such as when insufficient aerosol-forming liquid is provided to the heating element. The method may include determining a maximum electrical resistance of the heating element during each puff, calculating a rolling average of the maximum electrical resistance of the heating element during n previous heating cycles, where n is an integer greater than 1, comparing the electrical resistance of the heating element to the calculated rolling average, and determining a malfunction when the electrical resistance is greater than the rolling average by a resistance threshold, where the resistance threshold is stored in a computer-readable memory. The method may include determining a first or second derivative of the electrical resistance with respect to time, and determining a malfunction when the first or second derivative is greater than or equal to a first or second derivative threshold, where the first or second derivative threshold is stored in a computer-readable memory. The method may include calculating a resistance threshold, or a first or second derivative threshold, for each of the power values ​​of the plurality of power values ​​stored in the computer-readable memory. Alternatively, the method may include storing in the computer readable memory a resistance threshold, or a first or second derivative threshold, for each of a plurality of power values ​​stored in the computer readable memory. The method may include determining a malfunction when the resistance threshold, or the first or second derivative threshold, is exceeded during two consecutive puffs by the user. The method may include adjusting the resistance threshold, or the first or second derivative threshold, after the resistance threshold, or the first or second derivative threshold, is exceeded for the first time during a puff by the user.

[0028] According to a third aspect of the present disclosure, there is provided an aerosol generation system comprising an airflow passage extending between an air inlet and an air outlet, a heating element for heating an aerosol-forming substrate, a sensor assembly in communication with the airflow passage, the sensor assembly configured to measure a pressure or flow rate within the airflow passage, and a controller including a computer readable memory. The controller may be configured to read the pressure or flow rate measured by the sensor assembly at regular time intervals, detect the start of a puff when a user puffs on the aerosol generation system, select a power profile in a first mode from a plurality of power profiles stored in the computer readable memory, the selection depending on the pressure or flow rate read by the controller, and supply power to the heating element in accordance with the selected power profile.

[0029] The controller may be configured in a first mode to select a power profile at regular time intervals during a puff. In the first mode, the selection of the power profile may be based on the most recent pressure or flow rate read by the controller. In the first mode, the selection of the power profile may depend on the time since the start of the puff.

[0030] The duration of the regular time intervals may be between 1 ms and 1000 ms. Preferably, the duration of the regular time intervals is between 2 ms and 500 ms, more preferably, the duration of the regular time intervals is between 5 ms and 250 ms, even more preferably, the duration of the regular time intervals is between 10 ms and 100 ms, even more preferably, the duration of the regular time intervals is between 20 ms and 60 ms, even more preferably, the duration of the regular time intervals is substantially equal to 40 ms.

[0031] The computer readable memory preferably stores a look-up table, the look-up table including a plurality of power profiles, each power profile corresponding to a pressure range or flow rate range and a time range since the beginning of a puff. The controller may be configured to control the supply of power to the heating element in the first mode using the look-up table. Advantageously, such a look-up table may provide a curated aerosol generation for a user adapted to the user's puffing behavior. The time ranges may be of equal length. The time ranges may be between 0 ms and 2000 ms. Preferably, the length of the time ranges may be between 10 ms and 1500 ms. More preferably, the length of the time ranges may be between 50 ms and 1200 ms. Even more preferably, the length of the time ranges may be between 200 ms and 1000 ms. Even more preferably, the length of the time ranges may be between 600 ms and 800 ms. The time ranges may be of different lengths. This may mean that the time ranges best fit the typical pressure changes during a puff. The number of time ranges in the look-up table may be between 2 and 1000. The number of time ranges in the lookup table is preferably 2-100, more preferably 2-50, and even more preferably 2-20. The number of time ranges in the lookup table is even more preferably 2-10, more preferably 4-8, and even more preferably 5-7. In aspects of the present disclosure where pressure ranges or flow rates are used in the lookup table, the pressure ranges or flow rate ranges may be substantially equal in size. Alternatively, the pressure ranges or flow rate ranges may be different in size. This may mean that the pressure ranges or flow rate ranges better match the typical changes in pressure during a puff. The number of pressure ranges or flow rate ranges in the lookup table may be 2-1000, preferably 2-100, more preferably 2-50, even more preferably 2-20, even more preferably 2-15, even more preferably 4-10, and most preferably 7-9. The power profile may be flat, such that the power supplied to the heating element during the duration of the power profile is constant.Alternatively, each power profile may vary over time such that the power supplied to the heating element during the duration of the power profile may vary over time for regular time intervals. The change in the power profile over time may be an increase or decrease in power during the regular time interval, or the power may both increase and decrease at least once during the regular time interval. Such an increase or decrease may vary smoothly and continuously over time, or may be discontinuous. The multiple power profiles may include multiple different power profiles.

[0032] The power profile supplied to the heating element in the first mode may depend on the difference between a reference pressure or flow rate and a pressure or flow rate read by the controller. The controller may detect the start of a puff when the difference between the reference pressure or flow rate and a pressure or flow rate read by the controller exceeds a first threshold pressure or flow rate. The reference pressure or flow rate may be calculated by the controller as a rolling average of an integer number of pressure or flow rate values ​​read by the controller prior to detection of the start of a puff. The first threshold pressure or flow rate may be predetermined. The first threshold pressure or flow rate may be stored in a computer readable memory. The first threshold pressure or flow rate may be calculated as a percentage or as a multiple of the reference pressure or flow rate.

[0033] The controller may be configured to control the supply of power to the heating element in the second mode, the supply of power to the heating element in the second mode being independent of at least one of the measured time since the start of the puff and the pressure or flow rate read by the controller. In the second mode, the power supplied to the heating element may be constant for the duration of the puff. The controller may be further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The controller may be further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The controller may be further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The controller may be further configured to control the supply of power to the heating element in either the first mode or the second mode depending on a combination of at least two of the cumulative energy supplied to the heating element since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff, the cumulative puff time, and the number of puffs. The controller may be configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element within a specific time interval before the start of a puff. The controller may be configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative heating time of the heating element within a specific time interval before the start of a puff.

[0034] The aerosol generating system preferably comprises an aerosol generating device. The aerosol generating device may comprise a receptacle configured to receive an aerosol generating article or cartridge containing an aerosol-forming substrate. The aerosol generating article or cartridge may be coupled to and decoupled from the aerosol generating device.

[0035] The controller may be configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since the aerosol-generating article or cartridge was coupled to the aerosol generating device.The controller may be configured to control the supply of power to the heating element in either the first mode or the second mode depending on the accumulated time of puffs since the aerosol-generating article or cartridge was coupled to the aerosol generating device.

[0036] The controller may be configured to detect a malfunction in the heating element, such as when insufficient aerosol-forming liquid is provided to the heating element. The controller may be configured to determine a maximum electrical resistance of the heating element during each puff, calculate a rolling average of the maximum electrical resistance of the heating element during n previous heating cycles, where n is an integer greater than 1, compare the electrical resistance of the heating element to the calculated rolling average, and determine a malfunction when the electrical resistance is greater than the rolling average by a resistance threshold, where the resistance threshold is stored in a computer-readable memory. The controller may be configured to determine a first or second derivative of the electrical resistance with respect to time, and determine a malfunction when the first or second derivative is greater than or equal to a first or second derivative threshold, where the first or second derivative threshold is stored in a computer-readable memory. For either configuration, the resistance threshold, or the first or second derivative threshold, may depend on whether the supply of power to the heating element is controlled in a first mode or a second mode. The resistance threshold, or the first derivative value or the second derivative value threshold, is preferably dependent on the power supplied to the heating element. The resistance threshold, or the first derivative value or the second derivative value threshold may be calculated for each of the power profiles of the plurality of power profiles stored in the computer readable memory. The resistance threshold, or the first derivative value or the second derivative value threshold, corresponding to each of the power profiles of the plurality of power profiles stored in the computer readable memory may be stored in the computer readable memory. The controller may determine a malfunction when the resistance threshold, or the first derivative value or the second derivative value threshold, is exceeded during two consecutive puffs by the user. In this case, the resistance threshold, or the first derivative value or the second derivative value threshold may be adjusted after the resistance threshold, or the first derivative value or the second derivative value threshold, is exceeded during a puff by the user.

[0037] According to a fourth aspect of the present disclosure, there is provided a method of generating an aerosol in an aerosol generating system, the system comprising an airflow passage extending between an air inlet and an air outlet, a heating element for heating an aerosol-forming substrate, a sensor assembly in communication with the airflow passage, and a controller including a computer readable memory. The method may include detecting the start of a puff in a first mode, reading an output from the sensor assembly to determine a pressure or flow rate in the airflow passage, selecting a power profile from a plurality of power profiles stored in the memory, the selection being dependent on the pressure or flow rate in the airflow passage, and supplying power to the heating element in accordance with the selected power profile.

[0038] Preferably, in the first mode, the output from the sensor assembly is read at regular time intervals. In the first mode, the supply of power to the heating element may depend on the difference between a reference pressure or flow rate and the pressure or flow rate in the airflow passage.

[0039] The method may further include, in the first mode, selecting a power value from a lookup table stored in the computer readable memory based on the pressure or flow rate in the airflow passage and the time since the start of the puff, the lookup table including a plurality of power values, each power value corresponding to a range of pressures, or flow rates, and a range of times since the start of the puff, and supplying power to the heating element based on the selected power value.

[0040] The method may include a controller reading an output from the sensor assembly to determine a pressure or flow rate in the airflow passage. The method may include detecting the onset of a puff when a difference between a baseline pressure or baseline flow rate and the pressure or flow rate in the airflow passage exceeds a first threshold pressure or first threshold flow rate. The baseline pressure or baseline flow rate may be calculated by the controller as a rolling average of an integer number of pressure or flow values ​​in the airflow passage prior to detection of the onset of a puff.

[0041] The method may include controlling the supply of power to the heating element in a second mode. The supply of power to the heating element in the second mode may be independent of at least one of a measured time since the start of the puff and a pressure or a flow rate in the airflow passage. In the second mode, the power supplied to the heating element may be constant for the duration of the puff.

[0042] The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the number of puffs since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the cumulative puff time since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the cumulative energy supplied to the heating element since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on a combination of at least two of the cumulative energy supplied to the heating element, the cumulative puff time, and the number of puffs since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. The method may include controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element within a specified time interval before the start of a puff. The method may include controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative heating time of the heating element within a specified time interval before the start of a puff.

[0043] The aerosol generating system may comprise an aerosol generating device. The aerosol generating device may comprise a receptacle configured to receive an aerosol generating article or cartridge containing an aerosol-forming substrate. The aerosol generating article or cartridge may be coupled to and decoupled from the aerosol generating device. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the number of puffs since the aerosol generating article or cartridge was coupled to the aerosol generating device. The method may include controlling the supply of power to the heating element in either a first mode or a second mode depending on the accumulated puff time since the aerosol generating article or cartridge was coupled to the aerosol generating device.

[0044] The method may include detecting a malfunction in the heating element, such as when insufficient aerosol-forming liquid is provided to the heating element. The method may include determining a maximum electrical resistance of the heating element during each puff, calculating a rolling average of the maximum electrical resistance of the heating element during n previous heating cycles, where n is an integer greater than 1, comparing the electrical resistance of the heating element to the calculated rolling average, and determining a malfunction when the electrical resistance is greater than the rolling average by a resistance threshold, where the resistance threshold is stored in a computer-readable memory. The method may include determining a first or second derivative of the electrical resistance with respect to time, and determining a malfunction when the first or second derivative is greater than or equal to a first or second derivative threshold, where the first or second derivative threshold is stored in a computer-readable memory. The method may include calculating a resistance threshold, or a first or second derivative threshold, for each power profile of a plurality of power profiles stored in the computer-readable memory. Alternatively, the method may include storing in the computer readable memory a resistance threshold or a first or second derivative threshold for each of a plurality of power profiles stored in the computer readable memory. The method may include determining a malfunction when the resistance threshold or the first or second derivative threshold is exceeded during two consecutive puffs by the user. The method may include adjusting the resistance threshold or the first or second derivative threshold after the resistance threshold or the first or second derivative threshold is exceeded for the first time during a puff by the user.

[0045] As used herein in connection with the present invention, the term "aerosol" is used to describe a dispersion of solid particles, or liquid droplets, or a combination of solid particles and liquid droplets, in a gas. Aerosols can be visible or invisible. Aerosols may include vapors of substances that are normally liquids or solids at room temperature, as well as solid particles, or liquid droplets, or a combination of solid particles and liquid droplets.

[0046] As used herein, "aerosol-generating system" refers to a system that generates an aerosol from one or more aerosol-forming substrates.

[0047] The term "aerosol-forming substrate" as used herein means a substrate capable of releasing volatile compounds capable of forming an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate.

[0048] As used herein, the term "puffing" is used to describe the action of a user generating an aerosol using an aerosol generation system. The user performs this action by drawing air through the aerosol generation system via inhalation.

[0049] As used herein, the terms "air inlet" and "air outlet" are used to describe one or more openings through which air may be drawn into and out of, respectively, a component or portion of a component of an aerosol generating article, an aerosol generating system, or an aerosol generating device.

[0050] The term "aerosol-generating article" as used herein refers to an article comprising an aerosol-forming substrate capable of releasing a volatile compound capable of forming an aerosol. The aerosol-generating article may be disposable. The aerosol-generating article is preferably a smoking article that generates an aerosol that can be inhaled directly through the user's mouth into the user's lungs. More preferably, the aerosol-generating article is a smoking article that generates a nicotine-containing aerosol that can be inhaled directly through the user's mouth into the user's lungs. The aerosol-generating article may be a heat-non-combustion article.

[0051] For example, the aerosol-generating device may comprise a substrate-receiving cavity for receiving a consumable aerosol-generating article comprising the aerosol-forming substrate. The aerosol-forming substrate in the aerosol-generating article may be a solid aerosol-forming substrate. Examples of aerosol-generating articles include sachets filled with solid aerosol-forming substrates, cigarettes, and cigarette-like articles comprising the aerosol-forming substrate contained within a wrapper, capsule, or container, such as cigarette paper, of liquid or colloidal aerosol-forming substrate. Consumable aerosol-generating articles may comprise replaceable substrate sections containing two or more components that combine to form an aerosol. A preferred consumable aerosol-generating article may be in the form of a cigarette or cigarette-like article comprising a solid aerosol-forming substrate contained within a wrapper. Such articles preferably comprise a mouth end intended to be inserted into the mouth of a user for consumption of the article. The mouth end preferably comprises a filter that mimics a conventionally prepared cigarette. The consumable aerosol-generating article is preferably configured to interact with an atomizer, preferably a heater, located within the body of the aerosol-generating device. Hence, a heating means such as a resistive heating element may be located within or around a substrate-receiving cavity for receiving the consumable aerosol-generating article. The substrate-receiving cavity may be located at the proximal end of the device. For example, an opening to the substrate-receiving cavity may be located at the proximal end of the device.

[0052] Preferably the aerosol-forming substrate comprises nicotine. More preferably the aerosol-forming substrate comprises tobacco. Alternatively, or additionally, the aerosol-forming substrate may comprise a non-tobacco-containing aerosol-forming material.

[0053] Where the aerosol-forming substrate is a solid aerosol-forming substrate, the solid aerosol-forming substrate may comprise, for example, one or more of powders, granules, pellets, shreds, threads, strips, or sheets containing one or more of herb leaves, tobacco leaves, tobacco stems, expanded tobacco, and homogenized tobacco.

[0054] Optionally, the solid aerosol-forming substrate may contain tobacco or non-tobacco volatile flavour compounds, which are released upon heating of the solid aerosol-forming substrate. The solid aerosol-forming substrate may also contain one or more capsules, e.g., containing additional tobacco or non-tobacco volatile flavour compounds, which may melt during heating of the solid aerosol-forming substrate.

[0055] Optionally, the solid aerosol-forming substrate may be provided on or embedded in a thermally stable carrier. The carrier may take the form of a powder, granules, pellets, pieces, threads, strips, or sheets. The solid aerosol-forming substrate may be deposited on the surface of the carrier, for example in the form of a sheet, foam, gel, or slurry. The solid aerosol-forming substrate may be deposited on the entire surface of the carrier, or alternatively, in a pattern to provide a non-uniform flavor delivery during use.

[0056] In one preferred embodiment, the aerosol-forming substrate comprises a homogenized tobacco material. As used herein, the term "homogenized tobacco material" refers to a material formed by agglomerating particulate tobacco.

[0057] The aerosol-forming substrate preferably comprises an assembly of a sheet of homogenized tobacco material. As used herein, the term "sheet" refers to a layered element having a width and length substantially greater than its thickness. As used herein, the term "assembled" is used to describe a sheet that is rolled, folded, or otherwise compressed or clamped substantially transversely to the longitudinal axis of the aerosol-generating article.

[0058] The term "cartridge" as used herein also refers to an article that includes an aerosol-forming substrate capable of emitting a volatile compound capable of forming an aerosol. The cartridge may also be disposable.

[0059] The cartridge may contain a liquid. The liquid may include a volatile compound capable of forming an aerosol. The liquid may form an aerosol upon heating of the liquid. The aerosol-forming substrate may be a liquid. The aerosol-forming substrate may be a liquid at room temperature. The aerosol-forming substrate may be in another condensed form such as a solid at room temperature or in another condensed form such as a gel at room temperature. The volatile compound may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may include both liquid and solid components. The liquid aerosol-forming substrate may include nicotine. The nicotine-containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may include a plant-derived material. The liquid aerosol-forming substrate may include tobacco. The liquid aerosol-forming substrate may include a tobacco-containing material containing volatile tobacco flavour compounds that are released from the aerosol-forming substrate upon heating. The liquid aerosol-forming substrate may include a homogenized tobacco material. The liquid aerosol-forming substrate may include a non-tobacco-containing material. The liquid aerosol-forming substrate may include a homogenized plant-derived material.

[0060] The liquid aerosol-forming substrate may include one or more aerosol formers. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense, stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperature of the system. Examples of suitable aerosol formers include glycerin and propylene glycol. Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as dimethyl dodecanedioate, dimethyl tetradecanedioate, etc.). The liquid aerosol-forming substrate may include water, solvents, ethanol, plant extracts, and natural or artificial flavors. The liquid aerosol-forming substrate may include nicotine and at least one aerosol former. The aerosol former may be glycerin or propylene glycol. The aerosol former may include both glycerin and propylene glycol. The liquid aerosol-forming substrate may have a nicotine concentration of about 0.5% to about 10%, for example about 2%.

[0061] The heating element may be configured to be resistively heated by application of an electric current through the heating element. The heating element may be configured to be inductively heated by an electric current induced in the heating element by a varying magnetic field. The heating element may be configured to be inductively heated by the hysteresis effect.

[0062] The heating element may take any form suitable for heating the aerosol-forming substrate. In some embodiments, the heating element is fluid permeable. The heating element may comprise a plurality of conductive filaments. The aerosol generating element may comprise a fluid permeable mesh. The heating element may include a plurality of gaps or openings extending from the second side to the first side through which fluid may pass. The heating element may be an array of filaments, for example arranged parallel to one another. Preferably, the filaments may form a mesh. Alternatively, the conductive heating element may comprise an array of filaments or a weave of filaments. The conductive filaments may define gaps between the filaments, which may have a width of 10 micrometers to 100 micrometers. The filaments preferably create capillary action in the gaps, such that liquid to be vaporized in use is drawn into the gaps, increasing the contact area between the heating element and the liquid aerosol-forming substrate.

[0063] The conductive filaments may have a diameter of 8 micrometers to 100 micrometers, preferably 10 micrometers to 50 micrometers, more preferably 12 micrometers to 25 micrometers, and most preferably approximately 16 micrometers. The filaments may have a round or flattened cross-section.

[0064] The aerosol generating element may be configured to be resistively heated. In other words, the aerosol generating element may be configured to generate heat when an electric current is passed through the heating element. The heating element, or portions thereof, may comprise or be formed of any material having suitable electrical and mechanical properties, such as a suitable electrically resistive material. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide, etc.), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may include doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals.

[0065] The electrical resistance of the mesh, array or weave of conductive filaments of the heater element is preferably 0.3 to 4 ohms. More preferably, the electrical resistance of the mesh, array or weave of conductive filaments is 0.5 to 3 ohms, and more preferably about 1 ohm. The electrical resistance is preferably 0.5 ohms or greater. More preferably, the electrical resistance of the mesh, array or weave of conductive filaments is 0.6 to 0.8 ohms, and most preferably about 0.68 ohms. Alternatively, the heating element may comprise a heating plate having an array of openings formed therein. The openings may be formed, for example, by etching or machining. The plate may be formed of any material having suitable electrical properties, such as those materials described above with respect to the filaments of the heating element.

[0066] The heating element may be an internal heater designed to be inserted into the consumable aerosol-generating article, for example a resistive heating element or susceptor in the form of a pin or blade that can be inserted into an aerosol-forming substrate located within the consumable aerosol-generating article. The heating element may be an external heater designed to heat an external surface of the consumable aerosol-generating article, for example a resistive heating element or a susceptor located around or surrounding a cavity that receives a substrate for receiving the consumable aerosol-generating article.

[0067] The aerosol generating element may comprise a susceptor element. In other words, the aerosol generating element may be configured to operate by inductive heating. During operation, the susceptor may be heated by eddy currents induced in the susceptor. Hysteresis losses may also contribute to the inductive heating.

[0068] The aerosol generating device may include a power source, for example a battery. The power source may be a DC power source. The power source may be a battery. The battery may be a lithium-based battery, for example a lithium cobalt battery, a lithium iron phosphate battery, a lithium titanate battery, or a lithium polymer battery. The battery may be a nickel metal hydride battery or a nickel cadmium battery. The power source may be another form of charge storage device, such as a capacitor.

[0069] The power source may be connected to the heating element. The aerosol generating device may comprise a controller. The controller may be connected to the power source. The controller may be connected to the heating element. The controller may control the supply of power from the power source to the heating element. The controller may control the temperature of the heating element. The controller may comprise a microcontroller. The microcontroller may be a programmable microcontroller.

[0070] The aerosol generation system may be a handheld aerosol generation system configured to allow a user to draw on the mouthpiece to draw aerosol through the first air outlet. The aerosol generation system may have a size comparable to a conventional cigar or cigarette. The aerosol generation system may have a total length of about 25 mm to about 150 mm. The aerosol generation system may have an outer diameter of about 5 mm to about 30 mm.

[0071] The present invention is defined in the claims. However, below is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein.

[0072] Example 1: An aerosol generation system comprising: an air inlet and an air outlet; an airflow passage extending between the air inlet and the air outlet; a heating element for heating an aerosol-forming substrate; a sensor assembly in fluid communication with the airflow passage, the sensor assembly configured to measure a pressure or flow rate within the airflow passage; and a controller configured to detect the start of a puff, read the pressure or flow rate measured by the sensor assembly, and control the supply of power to the heating element in a first mode in response to the start of the puff, wherein the controller controls the supply of power to the heating element in the first mode in dependence on both the time since the start of the puff and the pressure or flow rate read by the controller after the start of the puff. Example 2: An aerosol generation system according to Example 1, wherein the controller is further configured to read pressure or flow rate from the sensor assembly in the first mode at regular time intervals. Example 3: An aerosol generation system according to Example 1 or 2, wherein the controller includes a computer-readable memory storing a lookup table, the lookup table including a plurality of power values, each power value corresponding to a pressure range or flow rate range and a time range after the start of puffing, and the controller is further configured to control the supply of power to the heating element using the lookup table in the first mode. Example 4: An aerosol generation system according to any of Examples 1 to 3, wherein the supply of power to the heating element in the first mode depends on the difference between a reference pressure or reference flow rate and the pressure or flow rate read by the controller. Example 5: An aerosol generation system according to Example 4, wherein the controller detects the start of a puff when the difference between a reference pressure or reference flow rate and the pressure or flow rate read by the controller exceeds a first threshold pressure or a first threshold flow rate. Example 6: An aerosol generation system according to example 4 or 5, wherein the reference pressure or reference flow rate is calculated by the controller as a rolling average of the integer number of pressure or flow rate values ​​read by the controller prior to detection of the start of a puff. Example 7: An aerosol generation system according to Example 5, wherein the first threshold pressure or first threshold flow rate is calculated as a percentage or multiple of the reference pressure or reference flow rate. Example 8: An aerosol generating system according to example 5, wherein the first threshold pressure or the first threshold flow rate is predetermined. Example 9: An aerosol generating system according to Example 8, wherein the first threshold pressure or the first threshold flow rate is stored in a computer readable memory. Example 10: An aerosol generating system according to any one of Examples 3 to 9, wherein the look-up table includes time ranges from 2 to 10. Example 11: An aerosol generating system according to any one of Examples 3 to 10, wherein the length of the time range is from 200 milliseconds to 1000 milliseconds. Example 12: An aerosol generating system according to any of Examples 3 to 11, wherein the look-up table includes pressure or flow ranges from 2 to 15. Example 13: An aerosol generating system according to any of Examples 2 to 12, wherein the duration of the regular time intervals is 10 to 100 milliseconds. Example 14: An aerosol generation system according to any of Examples 1 to 13, wherein the controller is further configured to control the supply of power to the heating element in the second mode, and the supply of power to the heating element in the second mode is independent of at least one of the measured time since the start of puffing and the pressure or flow rate read by the controller. Example 15: An aerosol generating system according to Example 14, wherein in a second mode, the power supplied to the heating element is constant for the duration of the puff. Example 16: An aerosol generation system according to Example 14 or 15, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since one of the following occurs: the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 17: An aerosol generation system according to Example 14 or 15, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 18: An aerosol generation system according to claim 14 or 15, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since one of the following events: the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 19: An aerosol generation system according to Example 14 or 15, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on a combination of at least two of the cumulative energy supplied to the heating element after one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff, the cumulative puff time, and the number of puffs. Example 20: An aerosol generation system according to Examples 14 or 15, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element within a certain time interval before the start of puffing. Example 21: An aerosol generation system according to Examples 14 or 15, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative heating time of the heating element within a particular time interval prior to the start of smoking. Example 22: An aerosol generating system according to Example 14 or 15, comprising an aerosol generating device, the aerosol generating device including a receptacle configured to receive an aerosol generating article or cartridge containing an aerosol-forming substrate, the aerosol generating article or cartridge being capable of being connected to and disconnected from the aerosol generating device. Example 23: An aerosol generating system according to Example 22, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 24: An aerosol generating system according to Example 22, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 25: An aerosol generating system according to Example 22, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 26: An aerosol generation system according to any of Examples 1 to 25, wherein the supply of power to the heating element is controlled by controlling at least one of the voltage or current supplied to the heating element. Example 27: 27. An aerosol generating system according to Example 26, wherein the voltage or current is controlled by pulse width modulation. Example 28: The aerosol generating system according to any one of Examples 1 to 27, wherein the heating element is a resistive heating element. Example 29: 29. The aerosol generating system according to Example 28, wherein the resistive heating element is a mesh, array, or woven fabric of conductive filaments. Example 30: An aerosol generating system according to Example 29, wherein an aerosol generating article or cartridge containing the aerosol-forming substrate supplies aerosol-forming liquid to the resistive heating element, and the controller is further configured to detect when insufficient aerosol-forming liquid is supplied to the resistive heating element. Example 31: An aerosol generating system according to Example 30, wherein the controller is configured to detect when insufficient aerosol-forming liquid is supplied to the resistive heating element when the electrical resistance, the first derivative of the electrical resistance with respect to time, or the second derivative of the electrical resistance with respect to time is greater than a rolling average value beyond a resistance threshold, or a first derivative threshold, or a second derivative threshold, and the resistance threshold, or the first derivative threshold, or the second derivative threshold, is stored in a computer-readable memory. Example 32: An aerosol generating system according to Example 31, wherein the resistance threshold, or the first derivative value threshold, or the second derivative value threshold, depends on whether the supply of power to the heating element is controlled in the first mode or the second mode. Example 33: An aerosol generating system according to Example 31 or 32, wherein the resistance threshold, or the first derivative threshold, or the second derivative threshold, depends on the power supplied to the heating element. Example 34: A method of generating an aerosol in an aerosol generating system, the system comprising an airflow passage extending between an air inlet and an air outlet, a heating element for heating an aerosol-forming substrate, a sensor assembly in communication with the airflow passage, and a controller including a computer-readable memory, the method including: detecting, in a first mode, the start of a puff; reading an output from the sensor assembly to determine a pressure or flow rate in the airflow passage; and providing a supply of power to the heating element depending on both the time since the start of the puff and the pressure or flow rate in the airflow passage. Example 35: A method of generating an aerosol in an aerosol generating system according to Example 34, wherein in a first mode, the output from the sensor assembly is read at regular time intervals. Example 36: A method of generating an aerosol in an aerosol generating system according to Example 35, wherein in a first mode, the supply of power to the heating element depends on the difference between a reference pressure or reference flow rate and the pressure or flow rate in the airflow passage. Example 37: The method of generating an aerosol in an aerosol generating system according to Example 35 or 36, wherein the method further comprises, in a first mode, selecting a power value from a look-up table stored in a computer-readable memory based on the pressure or flow rate in the airflow passage and the time since the start of the puff, the look-up table including a plurality of power values, each power value corresponding to a pressure range, or flow rate range, and a time range since the start of the puff, and supplying power to the heating element based on the selected power value. Example 38: A method of generating an aerosol in an aerosol generating system according to any of Examples 34 to 37, wherein the method further comprises detecting the start of a puff when a difference between a reference pressure or reference flow rate and a pressure or flow rate in the airflow passage exceeds a first threshold pressure or a first threshold flow rate. Example 39: A method for generating an aerosol in an aerosol generating system according to any of Examples 34 to 38, wherein the method further includes controlling power supplied to the heating element in the second mode, and wherein the supply of power to the heating element in the second mode is independent of at least one of a measured time since the start of puffing, and the pressure or flow rate in the airflow passage. Example 40: A method of generating an aerosol in an aerosol generating system according to Example 39, wherein in a second mode, the supply of power to the heating element is constant for the duration of the puff. Example 41: A method for generating an aerosol in an aerosol generating system according to Example 39 or 40, the method further comprising controlling the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since one of the following occurs: the aerosol generating system is reset, the aerosol generating system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 42: A method for generating an aerosol in an aerosol generation system according to Example 39 or 40, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 43: A method for generating an aerosol in an aerosol generation system according to Example 39 or 40, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since one of the following events: the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 44: A method for generating an aerosol in an aerosol generation system according to Example 39 or 40, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on a combination of at least two of the cumulative energy supplied to the heating element, the cumulative puff time, and the number of puffs after one of the following occurs: the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 45: A method of generating an aerosol in an aerosol generating system according to Example 39 or 40, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element within a specified time interval before the start of a puff. Example 46: A method of generating an aerosol in an aerosol generating system according to Example 39 or 40, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative heating time of the heating element within a specified time interval prior to the start of smoking. Example 47: A method of generating an aerosol in an aerosol generating system according to Example 39 or 40, wherein the aerosol generating system comprises an aerosol generating device, the aerosol generating device including a receptacle configured to receive an aerosol generating article or cartridge containing an aerosol-forming substrate, and the aerosol generating article or cartridge can be connected to and disconnected from the aerosol generating device. Example 48: A method for generating an aerosol in an aerosol generating system according to Example 47, the method further comprising controlling the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 49: A method for generating an aerosol in an aerosol generating system according to Example 47, the method further comprising controlling the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 50: A method for generating an aerosol in an aerosol generating system according to Example 47, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 51: An aerosol generation system comprising: an airflow passage extending between an air inlet and an air outlet; a heating element for heating an aerosol-forming substrate; a sensor assembly in communication with the airflow passage, the sensor assembly configured to measure a pressure or flow rate in the airflow passage; and a controller including a computer-readable memory, wherein the controller is configured to: read the pressure or flow rate read by the sensor assembly at regular time intervals; in a first mode, detect the start of a puff when a user puffs on the aerosol generation system; select a power profile from a plurality of power profiles stored in the computer-readable memory, the selection being dependent on the pressure or flow rate read by the controller; and supply power to the heating element in accordance with the selected power profile. Example 52: An aerosol generation system according to Example 51, wherein the controller is configured in a first mode to select a power profile at regular time intervals during a puff. Example 53: An aerosol generation system according to Example 52, wherein in a first mode, the selection of the power profile is based on the most recent pressure or flow rate read by the controller. Example 54: An aerosol generation system according to Examples 51, 52 or 53, wherein in a first mode, the selection of the power profile depends on the time since the start of the puff. Example 55: An aerosol generating system according to Example 54, wherein the computer-readable memory stores a lookup table, the lookup table including a plurality of power profiles, each power profile corresponding to a pressure range or flow rate range and a time range after the start of puffing, and the controller is further configured to control the supply of power to the heating element using the lookup table in the first mode. Example 56: An aerosol generation system according to any of Examples 51 to 55, wherein the power profile supplied to the heating element in the first mode depends on the difference between a reference pressure or reference flow rate and the pressure or flow rate read by the controller. Example 57: An aerosol generation system according to Example 56, wherein the controller detects the start of a puff when the difference between a reference pressure or reference flow rate and the pressure or flow rate read by the controller exceeds a first threshold pressure or a first threshold flow rate. Example 58: An aerosol generation system according to Example 57, wherein the reference pressure or reference flow rate is calculated by the controller as a rolling average of the integer number of pressure or flow rate values ​​read by the controller prior to detection of the start of a puff. Example 59: An aerosol generation system according to any of Examples 51 to 58, wherein the controller is further configured to control the supply of power to the heating element in the second mode, and the supply of power to the heating element in the second mode is independent of at least one of the measured time since the start of the puff and the pressure or flow rate read by the controller. Example 60: An aerosol generating system according to Example 59, wherein in a second mode, the power supplied to the heating element is constant for the duration of the puff. Example 61: An aerosol generation system according to Example 59 or 60, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs after one of the following: the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 62: An aerosol generation system according to Example 59 or 60, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 63: An aerosol generation system according to Example 59 or 60, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since one of the following events: the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 64: An aerosol generation system according to Example 59 or 60, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on a combination of at least two of the cumulative energy supplied to the heating element after one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff, the cumulative puff time, and the number of puffs. Example 65: An aerosol generation system according to Examples 59 or 60, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element within a particular time interval prior to the start of puffing. Example 66: An aerosol generation system according to Example 59 or 60, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative heating time of the heating element within a particular time interval prior to the start of smoking. Example 67: An aerosol generating system according to Example 59 or 60, comprising an aerosol generating device, the aerosol generating device including a receptacle configured to receive an aerosol generating article or cartridge containing an aerosol-forming substrate, the aerosol generating article or cartridge being capable of being connected to and disconnected from the aerosol generating device. Example 68: An aerosol generating system according to Example 67, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 69: An aerosol generating system according to Example 67, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puffing time since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 70: An aerosol generating system according to Example 67, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 71: An aerosol generation system according to any of Examples 51-70, wherein the power profile is flat such that the power to the heating element is constant for the duration of the power profile. Example 72: An aerosol generation system according to any of Examples 51-70, wherein each power profile varies over time such that the power supplied to the heating element during the duration of the power profile varies over time during regular time intervals. Example 73: An aerosol generation system according to any of Examples 51-72, wherein the plurality of power profiles comprises a plurality of different power profiles. Example 74: A method of generating an aerosol in an aerosol generating system, the system comprising an airflow passage extending between an air inlet and an air outlet, a heating element for heating an aerosol-forming substrate, a sensor assembly in communication with the airflow passage, and a controller including a computer-readable memory, the method including: detecting the start of a puff in a first mode; reading an output from the sensor assembly to determine a pressure or flow rate in the airflow passage; selecting a power profile from a plurality of power profiles stored in the computer-readable memory, the selection being dependent on the pressure or flow rate in the airflow passage; and supplying power to the heating element in accordance with the selected power profile. Example 75: A method of generating an aerosol in an aerosol generating system according to Example 74, wherein in a first mode, the selection of the power profile depends on the time since the start of the puff. Example 76: A method of generating an aerosol in an aerosol generating system according to Example 75, wherein in a first mode, the output from the sensor assembly is read at regular time intervals. Example 77: A method of generating an aerosol in an aerosol generating system according to Example 76, wherein in a first mode, the selection of the power profile depends on the difference between a reference pressure or reference flow rate and the pressure or flow rate in the airflow passage. Example 78: An aerosol generating method in an aerosol generating system according to any of Examples 74 to 77, wherein the method further comprises detecting the start of a puff when a difference between a reference pressure or reference flow rate and a pressure or flow rate in the airflow passage exceeds a first threshold pressure or a first threshold flow rate. Example 79: A method for generating an aerosol in an aerosol generating system according to any of Examples 74 to 78, wherein the method further includes controlling power supplied to the heating element in the second mode, and the supply of power to the heating element in the second mode is independent of at least one of a measured time since the start of puffing, and the pressure or flow rate in the airflow passage. Example 80: A method of generating an aerosol in an aerosol generating system according to Example 79, wherein in a second mode, the supply of power to the heating element is constant for the duration of the puff. Example 81: The method of generating an aerosol in an aerosol generating system according to Example 79 or 80, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since one of the following occurs: the aerosol generating system is reset, the aerosol generating system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 82: The method of generating an aerosol in an aerosol generation system according to Example 79 or 80, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 83: The method of generating an aerosol in an aerosol generating system according to Example 79 or 80, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since one of the following events: the aerosol generating system is reset, the aerosol generating system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 84: The method of generating an aerosol in an aerosol generating system according to Example 79 or 80, further comprising controlling the supply of power to the heating element in either the first mode or the second mode depending on a combination of at least two of the cumulative energy supplied to the heating element, the cumulative puff time, and the number of puffs after one of the following occurs: the aerosol generating system is reset, the aerosol generating system is turned on, or the heating element is cooled to ambient temperature after at least one puff. Example 85: A method of generating an aerosol in an aerosol generating system according to Example 79 or 80, wherein the method further comprises controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element within a specified time interval before the start of a puff. Example 86: A method of generating an aerosol in an aerosol generating system according to Example 79 or 80, the method further comprising controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative heating time of the heating element within a specified time interval prior to the start of smoking. Example 87: A method of generating an aerosol in an aerosol generating system according to Example 79 or 80, wherein the aerosol generating system comprises an aerosol generating device, the aerosol generating device including a receptacle configured to receive an aerosol generating article or cartridge containing an aerosol-forming substrate, and the aerosol generating article or cartridge can be connected to and disconnected from the aerosol generating device. Example 88: A method for generating an aerosol in an aerosol generating system according to Example 87, the method further comprising controlling the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 89: A method for generating an aerosol in an aerosol generating system according to Example 87, the method further comprising controlling the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puffing time since the aerosol generating article or cartridge is connected to the aerosol generating device. Example 90: A method for generating an aerosol in an aerosol generating system according to Example 87, the method further comprising controlling the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element since the aerosol generating article or cartridge is connected to the aerosol generating device.

[0073] The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0074] [Figure 1] FIG. 1 shows a schematic diagram of an aerosol generation system according to the present disclosure. [Diagram 2] FIG. 2 shows a schematic diagram of a controller according to the present disclosure. [Diagram 3] FIG. 3 shows a flow diagram of a method for detecting a puff and powering a heating element in either a first mode or a second mode. [Figure 4] FIG. 4 shows a flow diagram of another method for detecting a puff and powering a heating element in either a first mode or a second mode. [Diagram 5] FIG. 5 shows an exemplary display of a puff profile of pressure differential versus time. [Figure 6] FIG. 6 illustrates an example lookup table used by a controller in accordance with the present disclosure. [Figure 7] FIG. 7 shows an example table of power supply modes associated with the number of puffs. [Figure 8] FIG. 8 shows an example table of cumulative puff time ranges and associated power supply modes. [Figure 9] FIG. 9 is an alternative example of a mode lookup table that may be used by the controller to determine whether to control the supply of power supplied to the heating element in either the first mode or the second mode, according to a further alternative exemplary embodiment. [Figure 10]FIG. 10 is an alternative example of a mode lookup table that may be used by a controller to determine whether to control the supply of power to a heating element in either a first mode or a second mode, according to a further alternative exemplary embodiment. [Figure 11] FIG. 11 is an alternative example of a mode lookup table that may be used by a controller to determine whether to control the supply of power to a heating element in either a first mode or a second mode, according to a further alternative exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0075] 1 is a schematic diagram of an aerosol generation system 10 comprising an aerosol generation device 40 and an aerosol generation cartridge 20. The aerosol generation device 40 is configured to receive the aerosol generation cartridge 20. The aerosol generation cartridge 20 and the aerosol generation device 40 are coupled together and can be decoupled from each other by a user. The device comprises a power source 41 in the form of a battery and a controller 60 including control circuitry coupled to the power source 41.

[0076] The aerosol generating cartridge 20 includes a housing 22 that forms a mouthpiece for the system. Within the housing is a reservoir 24 that holds a liquid aerosol-forming substrate 26. A capillary body 27 is disposed adjacent the open end of the liquid reservoir 24. An electric heater 30 is provided adjacent an outer surface of the capillary body 27 such that the capillary body 27 can transport the liquid aerosol-forming substrate 26 from the liquid reservoir 24 to the electric heater 30. The capillary body 27 and the electric heater 30 together form at least a part of a heater assembly 31. The electric heater 30 is also disposed adjacent an airflow path within the aerosol generating cartridge 20. The airflow path is indicated by curved arrows in FIG. 1. The airflow path extends from an air inlet 28a to an air outlet 28b formed in an opening at the mouth end of the aerosol-generating article housing 22. 1, when the aerosol generating cartridge 20 is coupled to an aerosol generating device 40, the electric heater 30 is electrically coupled to a power source 41. The device 40 thus functions to provide power to the electric heater 30 in the aerosol generating cartridge 20 to vaporize a liquid aerosol-forming substrate. The vaporized aerosol-forming substrate is entrained in an airflow through the system, the airflow being effected by a user puffing on the mouth end of the aerosol generating cartridge 20. The vaporized aerosol-forming substrate cools in the airflow, forming an aerosol before being drawn into the user's mouth.

[0077] A sensor assembly 50 including a pressure level sensor is disposed within the aerosol generation cartridge 20 adjacent to the airflow path. It will also be understood that the sensor assembly 50 may alternatively include a flow sensor, such that all references to pressure herein below may be replaced with flow. The sensor assembly 50 is coupled to a controller 60 and configured to transmit measurement data from the pressure level sensor to the controller 60. Although the sensor assembly 50 is shown in FIG. 1 as being disposed within the aerosol-generating article 20, it will be understood that the sensor assembly 50 may alternatively be disposed within the aerosol generation device 40 such that the airflow path passes at least partially through the aerosol generation cartridge 20. It will further be appreciated that the electric heater 30 may be disposed within the aerosol generation device 40.

[0078] 2 is a schematic block diagram of a controller 60 according to the present invention. The controller includes a receiving module 82 configured to receive measurement data from the sensor assembly 50, a determining module 81 configured to determine the amount of power provided to the heating element 30, and a power supply module 83 configured to initiate the supply of power to the heating element 30. The determining module 81 is coupled to a clock 84 and a computer readable memory 85. A look-up table is stored on the computer readable memory 85 and is used by the controller in the first mode to determine the power to provide to the heating element. An example of the look-up table is shown in FIG. 6. Also stored in the computer readable memory 85 are the mode look-up tables shown in FIGS. 7, 8, 9, 10, and 11, as well as a first threshold pressure defined below.

[0079] 3 is a flow diagram showing a method of detecting puffs and powering a heating element in either a first mode or a second mode according to the present invention. In step 100, after a user turns on, resets, or inserts an aerosol-generating article into the device, the controller is configured to read the pressure measured by the sensor assembly at regular time intervals. The controller compares the pressure measured by the sensor assembly to a rolling average of pressure based on N previous pressures measured by the sensor assembly, where N is an integer selected by the manufacturer of the aerosol-generating system. The rolling average of pressure is referred to as the baseline pressure. The baseline pressure is stored and updated in the computer-readable memory 85 and is read from the computer-readable memory 85 by the controller.

[0080] The difference between the pressure measured by the sensor assembly and the reference pressure is referred to as ΔP. ​​Specifically, ΔP is calculated using Equation 1 below: (1) ΔP=P ref -P In the formula, P ref is the reference pressure and P is the pressure measured by the sensor assembly. Since the pressure at the sensor assembly is reduced when the user takes a puff, ΔP should be greater than zero when the user takes a puff.

[0081] The predetermined first threshold pressure is stored in a computer readable memory of the controller. If ΔP is less than or equal to the first threshold pressure, then in step 101 the controller recalculates the baseline pressure using the most recent pressure measured by the sensor assembly.

[0082] If ΔP is greater than the first threshold pressure, the controller does not recalculate the baseline pressure using the most recent pressure measured by the sensor assembly. In step 102, the time at which ΔP is greater than the first threshold pressure is registered by the controller as the start of a puff.

[0083] In the first and second exemplary embodiments according to the invention described, the method then includes step 103, where the controller determines whether to control the supply of power to the heating element in either the first mode or the second mode.

[0084] In a first exemplary embodiment, the controller determines whether to control the supply of power to the heating element in either the first mode or the second mode in step 103 after one of the following: the aerosol generating system is reset; the aerosol generating system is turned on; the heating element cools down to ambient temperature after at least one puff; or, in embodiments in which the aerosol generating system comprises an aerosol generating device and the aerosol generating device includes a receptacle configured to receive an aerosol-generating article or cartridge containing an aerosol-forming substrate, depending on the number of cumulative puffs since the aerosol-generating article or cartridge is coupled to the aerosol generating device. The controller determines in which mode to control the supply of power to the heating element by using a mode lookup table. An example of a mode lookup table is shown in FIG. 7. The mode lookup table is predetermined by the manufacturer and preloaded into the computer-readable memory 85.

[0085] Alternative indicators may be used to determine whether to control the supply of power to the heating element in either the first mode or the second mode. These include depending on one or both of the following: the aerosol generation system is reset; the aerosol generation system is turned on; the heating element cools down to ambient temperature after at least one puff; or, in embodiments where the aerosol generation system comprises an aerosol generation device, the aerosol generation device including a receptacle configured to receive an aerosol-generating article or cartridge containing an aerosol-forming substrate, the cumulative puff time since the aerosol-generating article or cartridge is coupled to the aerosol generation device, or the cumulative energy supplied to the heating element. Examples of mode look-up tables for two of these alternative exemplary embodiments are shown in Figures 8 and 9. The cumulative energy may be calculated by the controller from the current and voltage supplied to the heating element. Further alternative indicators include the controller being configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative energy supplied to the heating element or the cumulative puff time within a certain time interval before the start of a puff, and mode look-up tables for such further alternatives are shown in Figures 10 and 11.

[0086] In the first mode, the controller then controls the supply of power to the heating element based on ΔP and the time elapsed since the start of the puff, step 104. This is accomplished by the controller using a look-up table stored in computer readable memory, an example of which is shown in Figure 6. Each power value in the look-up table corresponds to both a range of ΔP and a range of time elapsed since the start of the puff. The controller uses the calculated value of ΔP and the time elapsed since the start of the puff to select a power value to be supplied to the heating element from the look-up table.

[0087] After a period of time, the controller reads a new pressure value measured by the sensor assembly in step 105. Using this new pressure value measured by the sensor assembly, the controller recalculates ΔP in step 106. If ΔP is greater than the second threshold pressure, the controller returns to step 104 and controls the supply of power to the heating element based on ΔP.

[0088] If ΔP is less than or equal to the second threshold pressure, the controller stops supplying power to the heating element and returns to step 100 to read the pressure measured by the sensor assembly at regular time intervals. This is indicated as the end of the puff, and the controller increments the puff count by 1. In a second exemplary embodiment, also according to the present invention, in which the controller determines whether to control the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time, the controller instead adds the duration of the puff to the accumulated puff time.

[0089] The time at which the aerosol generating system indicates the end of a puff depends on whether ΔP is less than or equal to a second threshold pressure, which is a predetermined percentage of the maximum ΔP determined by the controller since the start of the current puff. However, other events may instead be used to indicate the end of a puff, such as when ΔP is less than or equal to the threshold pressure, or when ΔP is less than or equal to a multiple of the threshold pressure.

[0090] In the second mode, the controller controls the supply of power to the heating element independent of ΔP and the time elapsed since the start of the puff, step 107. The power supplied to the heating element is a constant power as determined by a corresponding entry in the mode lookup table.

[0091] After a period of time, the controller reads a new pressure value measured by the sensor assembly in step 108. Using this new pressure value measured by the sensor assembly, the controller recalculates ΔP in step 109. If ΔP is greater than the second threshold pressure, the controller returns to step 107 and controls the supply of power to the heating element based on ΔP.

[0092] If ΔP is less than or equal to the second threshold pressure, the controller stops supplying power to the heating element and returns to step 100 to read the pressure measured by the sensor assembly at regular time intervals. This is indicated as the end of the puff, and the controller increments the puff count by 1. In a second exemplary embodiment, also according to the present invention, in which the controller determines whether to control the supply of power to the heating element in either the first mode or the second mode depending on the accumulated puff time, the controller instead adds the duration of the puff to the accumulated puff time.

[0093] 4 is a flow diagram illustrating a method of detecting a puff and powering a heating element in a first mode, also according to the present disclosure. The step of determining whether to control the supply of power to the heating element in either the first mode or the second mode is not included, and the controller powers the heating element only in the first mode. The method steps are otherwise identical to those described with respect to FIG.

[0094] 5 is a plot of an exemplary puff profile showing pressure differential versus time elapsed since the start of a puff. Pressure differential is defined as the difference between the reference pressure calculated by the controller and the pressure read by the controller from the sensor assembly. When a user puffs on the aerosol generation system, the pressure inside the system and at the sensor is reduced. The decrease in pressure read by the controller at the sensor results in an increase in the pressure differential calculated by the controller. The time is shown from the start of the puff detected by the controller.

[0095] The puff profile shows an initial increase in pressure differential as the user begins to puff on the aerosol generation system. The pressure differential increases linearly with time. The pressure differential then plateaus and remains constant for the period of time the user continues to puff on the aerosol generation system. The pressure differential then decreases as the user begins to stop puffing on the aerosol generation system. The time at which the aerosol generation system indicates the end of the puff is shown at point 201. The indication of the end of the puff at this point allows the user to continue to puff weakly on the aerosol generation system, but with no power applied to the heating element, allowing for subsequent flushing of the aerosol generation system.

[0096] The puff profile shown in Figure 5 is an ideal puff profile, and the puff profile may vary in shape from user to user and from puff to puff. There may be two or more pressure differential maxima and one or more pressure differential minima. Furthermore, the pressure differential may vary smoothly and non-linearly over time.

[0097] The plot shown in FIG. 5 is divided into a range of pressure differentials and ranges of time elapsed since the start of a puff.

[0098] There are eight pressure difference ranges. The first seven pressure difference ranges are not evenly spaced and can be selected to fit the smoke puff profile, although one skilled in the art will appreciate that these pressure difference ranges may be evenly spaced. Examples of pressure drop ranges are as follows: Pressure Range 1: 0 Pa to 150 Pa, Pressure Range 2: 150 Pa to 250 Pa, Pressure Range 3: 250 Pa to 500 Pa, Pressure Range 4: 500 Pa to 750 Pa, Pressure Range 5: 750 Pa to 1000 Pa, Pressure Range 6: 1000 Pa to 1750 Pa, Pressure Range 7: 1750 Pa to 2500 Pa, Pressure Range 8: 2500 Pa or greater.

[0099] There are also six ranges of time elapsed since the start of the puff. While the times elapsed since the start of the first five puffs are evenly spaced, these pressure difference ranges may not be evenly spaced and can be selected to fit a particular puff profile. Examples of ranges of time elapsed since the start of the puff are as follows: Time Range 1: 0 ms to 700 ms, Time Range 2: 700 ms to 1400 ms, Time Range 3: 1400 ms to 2100 ms, Time Range 4: 2100 ms to 2800 ms, Time Range 5: 2800 ms to 3500 ms, Time Range 6: 3500 ms or greater.

[0100] FIG. 6 is an example of a lookup table used by the controller to control the power provided to the heating element in the first mode. The lookup table includes a matrix of power values. The power for each power value is given in watts. Each power value is associated with a pressure differential range and a range of elapsed time since the start of the puff. The pressure differential range and the range of elapsed time since the start of the puff are the same as those described with respect to FIG. 5. In the first mode, the determination module 81 determines the amount of power to provide to the heater element by comparing ΔP to the pressure differential range and the elapsed time since the start of the puff to the range of elapsed time since the start of the puff. The user can change the system profile values ​​stored in the controller. When the system profile values ​​are changed, the power values ​​stored in the lookup table are changed to a matrix of different power values.

[0101] The look-up table may instead include a matrix of power profiles. Such a power profile is defined as power as a function of time. The power profile may be flat, such that the amount of power determined by the determination module 81 to supply to the heater element is constant for the duration of the regular time interval. In this case, the look-up table will result in substantially the same operation as the use of the look-up table shown in FIG. 6. However, alternatively, the power profile may be such that the amount of power determined by the determination module 81 to supply to the heater element varies with time during the regular time interval. The variation or power with time may be an increase or decrease during the regular time interval, or the power may both increase and decrease at least once during the regular time interval. For example, for one power profile input, the power may increase linearly from 5 watts to 10 watts during the first half of the regular time interval and then remain constant at 10 watts for the remaining part of the regular time interval. Such an increase or decrease may vary smoothly and continuously with time, or may be discontinuous. The matrix of power profiles may include a number of different power profiles.

[0102] 7 is an example of a mode look-up table that may be used by the controller to determine whether to control the supply of power to the heating element in either the first mode or the second mode according to an exemplary embodiment. The selection depends on the number of puffs taken by the user. Puff number 1 refers to the first puff taken by the user after one of the aerosol generating system is reset, the aerosol generating system is turned on, the heating element cools to ambient temperature after at least one puff, or, in embodiments where the aerosol generating system comprises an aerosol generating device and the aerosol generating device includes a receptacle configured to receive an aerosol-generating article or cartridge containing an aerosol-forming substrate, after the aerosol-generating article or cartridge is coupled to the aerosol generating device. The controller records and reads the number of puffs taken by the user in the computer-readable memory 85.

[0103] 8 is an alternative example of a mode lookup table that can be used by the controller to determine whether to control the supply of power to the heating element in either the first mode or the second mode according to an alternative exemplary embodiment. The selection depends on the cumulative puff time. The cumulative puff time is set to zero by the controller after one of the following: the aerosol generating system is reset, the aerosol generating system is turned on, the heating element cools down to ambient temperature after at least one puff, or, in an exemplary embodiment in which the aerosol generating system comprises an aerosol generating device and the aerosol generating device includes a receptacle configured to receive an aerosol-generating article or cartridge containing an aerosol-forming substrate, after the aerosol-generating article or cartridge is coupled to the aerosol generating device. The controller then records and reads the cumulative puff time on a computer-readable memory 85 using a clock 84.

[0104] FIG. 9 is an alternative example of a mode lookup table that may be used by the controller to determine whether to control the supply of power supplied to the heating element in either the first mode or the second mode according to a further alternative exemplary embodiment. The selection depends on the cumulative energy supplied to the heating element. The cumulative energy supplied to the heating element is set to zero by the controller after one of the following: the aerosol generating system is reset, the aerosol generating system is turned on, the heating element is cooled to ambient temperature after at least one puff, or, in an embodiment in which the aerosol generating system comprises an aerosol generating device and the aerosol generating device comprises a receptacle configured to receive an aerosol-generating article or cartridge containing an aerosol-forming substrate, after the aerosol-generating article or cartridge is coupled to the aerosol generating device. The controller then records and reads the cumulative energy supplied to the heating element on the computer-readable memory 85. The cumulative energy supplied to the heating element is calculated by the controller using the voltage and current supplied to the heating element by the controller. At least two of the parameters, the cumulative energy supplied to the heating element, the cumulative puff time, and the number of puffs, may be used in combination instead of only one of them. For example, the index value may be defined as the number of puffs multiplied by the cumulative puff time since one of the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element cools to ambient temperature after at least one puff, or, in exemplary embodiments where the aerosol generation system comprises an aerosol generation device and the aerosol generation device includes a receptacle configured to receive an aerosol-generating article or cartridge containing an aerosol-forming substrate, since the aerosol-generating article or cartridge is coupled to the aerosol generation device. Power may then be supplied to the heater element in either the first mode or the second mode depending on the value of the index value.

[0105] 10 and 11 are two alternative examples of mode lookup tables that may be used by a controller to determine whether to control the supply of power to a heating element in either a first mode or a second mode, according to further alternative exemplary embodiments. The selection depends on the cumulative energy supplied to the heating element within a particular time interval before the start of a puff, and the cumulative heating time of the heating element within a particular time interval before the start of a puff, respectively. For example, as shown in FIGS. 10 and 11, the selection may depend on the cumulative energy supplied to the heating element within the last five seconds before the start of a puff, and the cumulative heating time of the heating element, respectively.

[0106] The embodiment of the power control process described is an aerosol generating system that includes a cartridge containing a liquid aerosol-forming substrate and a resistive heater. However, the control process described can be used in other types of aerosol generating systems in which a user puffs and thereby experiences variable airflow during use. For example, the aerosol generating system may use inductive heating. The aerosol generating system may also be a heated non-combustion system that heats a solid aerosol-forming substrate within an aerosol-generating article similar to a cigarette.

Claims

1. 1. An aerosol generating system comprising: an air inlet and an air outlet; an air flow passage extending between the air inlet and the air outlet; a heating element for heating the aerosol-forming substrate; a sensor assembly in communication with the airflow passage, the sensor assembly configured to measure pressure or flow within the airflow passage; a controller configured to detect the start of a puff, read the pressure or the flow rate measured by the sensor assembly, and control the supply of power to the heating element in a first mode in response to the start of the puff; the controller controls the supply of power to the heating element in the first mode depending on both the time since the start of the puff and the pressure or the flow rate read by the controller after the start of the puff; An aerosol generation system wherein the controller includes a computer-readable memory storing a lookup table, the lookup table including a plurality of power values, each power value corresponding to a pressure range or flow rate range and a time range since the start of the puff, and the controller is further configured to control the supply of power to the heating element using the lookup table in the first mode.

2. 2. The aerosol generation system of claim 1, wherein the controller is further configured to read the pressure or the flow rate from the sensor assembly at regular time intervals in the first mode.

3. 3. The aerosol generating system of claim 1, wherein the supply of power to the heating element in the first mode depends on the difference between a reference pressure or a reference flow rate and the pressure or the flow rate read by the controller.

4. 4. The aerosol generation system of claim 3, wherein the controller detects the start of the puff when the difference between the reference pressure or the reference flow rate and the pressure or the flow rate read by the controller exceeds a first threshold pressure or a first threshold flow rate.

5. 4. The aerosol generation system of claim 3, wherein the reference pressure or reference flow rate is calculated by the controller as a rolling average of integer pressure or flow rate values ​​read by the controller prior to the detection of the start of the puff.

6. 2. The aerosol generation system of claim 1, wherein the controller is further configured to control the supply of power to the heating element in a second mode, and wherein the supply of power to the heating element in the second mode is independent of at least one of the measured time since the start of the puff and the pressure or the flow rate read by the controller.

7. 7. The aerosol generating system of claim 6, wherein in the second mode, the power supplied to the heating element is constant for the duration of the puff.

8. The aerosol generation system of claim 6 or 7, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since one of the following events: the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element is cooled to ambient temperature after at least one puff.

9. The aerosol generation system of claim 6 or 7, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative smoking time since one of the following events occurs: the aerosol generation system is reset, the aerosol generation system is turned on, or the heating element has cooled to ambient temperature after at least one smoking session.

10. 8. The aerosol generation system according to claim 6 or 7, comprising an aerosol generation device, the aerosol generation device including a receptacle configured to receive an aerosol-generating article or cartridge containing the aerosol-forming substrate, the aerosol-generating article or cartridge being connectable to and disconnectable from the aerosol generation device.

11. The aerosol generating system of claim 10, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the number of puffs since the aerosol generating article or cartridge was connected to the aerosol generating device.

12. 11. The aerosol generating system of claim 10, wherein the controller is further configured to control the supply of power to the heating element in either the first mode or the second mode depending on the cumulative puff time since the aerosol generating article or cartridge was connected to the aerosol generating device.

13. 1. A method of generating an aerosol in an aerosol generating system, the system comprising: an airflow passage extending between the air inlet and the air outlet; a heating element for heating the aerosol-forming substrate; a sensor assembly in communication with the airflow passage; a controller including a computer readable memory that stores a lookup table, the lookup table including a plurality of power values, each power value corresponding to a range of pressures or flow rates and a range of time since the start of a puff; The method, in a first mode, comprises: Detecting the onset of a puff; reading an output from the sensor assembly to determine a pressure or flow rate within the airflow passage; selecting a power value from a look-up table stored in said computer readable memory based on the pressure or flow rate in said airflow passage and the time since the start of said puff; and supplying power to the heating element in dependence upon both the time since the start of the puff and the pressure or the flow rate in the airflow passage and based on the selected power value.

14. 14. The method of generating an aerosol in an aerosol generating system according to claim 13, wherein in the first mode, the output from the sensor assembly is read at regular time intervals.

Images