Improved control of aerosol generation in aerosol generation systems

Abstract

This invention provides a method for controlling aerosol generation within an aerosol generation system. [Solution] The system (100) comprises an aerosol generating element (119) and a housing (101) having an air intake (123) and an air outlet (125). A flow path from the air intake (119) to the air outlet (123) provides an airflow through the aerosol generating element (119). The system (100) includes a flow sensor (109) configured to detect the airflow in the flow path. The method includes increasing the power supplied to the aerosol generating element (119) for at least a second time when the flow sensor (109) detects that the airflow rate has increased beyond a threshold. An aerosol generating system is also provided comprising a circuit arranged to carry out the method of the present invention.

Description

[Technical Field]

[0001] The present invention relates to a method for controlling aerosol generation in an aerosol generating system. The present invention further relates to an aerosol generating system. The present invention has a particular application as a method for controlling aerosol generation in an aerosol generating system through the control of the power supplied to the aerosol generating element of the aerosol generating system. [Background technology]

[0002] WO2012 / 072790 discloses a method for controlling at least one electric heating element in an electrically heated aerosol generating system for heating an aerosol-forming substrate. The aerosol generating system has a sensor for detecting airflow indicating that the user is performing smoke extraction with an airflow period. The method includes the steps of increasing the heating power to at least one heating element when the sensor detects that the airflow has increased to a first threshold, and decreasing the heating power to at least one heating element when the sensor detects that the airflow has decreased to a second threshold.

[0003] As disclosed in WO2012 / 072790, energy usage can be optimized by controlling the heating power supplied to at least one heating element. The heating power can be adjusted for a specific fume extraction profile so that desirable aerosol characteristics, such as a specific aerosol concentration or particle size, can be achieved. Unwanted overheating or underheating can also be avoided, particularly towards the start or end of fume extraction. A reduction in power towards the end of fume extraction affects the cooling of the heating element and therefore the temperature of the heating element and its vicinity. This, in turn, affects the amount of condensation that can form in the system, which may affect liquid leakage.

[0004] Disclosure WO2012 / 072790 teaches a method for minimizing the condensation of aerosols generated within an aerosol generator by reducing the heating power supplied to the aerosol generating element before the user finishes inhaling smoke. However, this can be frustrating for the user, especially in more complex smoke inhalation profiles, if insufficient aerosols are delivered to the user after the power supplied to the aerosol generating element is reduced.

[0005] An object of the present invention is to provide an improved method for controlling aerosol generation within an aerosol generation system. In particular, an object of the present invention is to provide an improved method for controlling aerosol generation in complex smoke extraction profiles. [Overview of the project]

[0006] According to a first aspect of the present invention, a method for controlling aerosol generation in an aerosol generating system is provided. The system comprises an aerosol generating element and a housing having an air intake and an air outlet. A flow path is defined through the housing from the air intake to the air outlet, and the flow path provides an airflow through the aerosol generating element when a user inhales smoke in the system. The system further comprises a flow sensor configured to detect the airflow in the flow path indicating that a user is inhaling smoke. The method comprises the following time-series steps: The process involves increasing the power supplied to the aerosol generating element from power P0 to at least power P1 when the flow sensor detects that the airflow rate is greater than a first threshold, and A process for reducing the power supplied to an aerosol generating element to power P2, wherein power P2 is less than power P1, and when a flow sensor detects that the airflow rate is less than a second threshold, the second threshold is a flow rate that is or indicates a predetermined first ratio of the first maximum flow rate detected by the flow sensor. The process includes increasing the power supplied to an aerosol generating element if, before detecting that the airflow rate is less than a smoke extraction termination threshold, the flow sensor detects that the airflow rate is greater than a third threshold, wherein the third threshold is greater than a second threshold and the smoke extraction termination threshold is less than a second threshold.

[0007] The steps of the method are presented in chronological order. That is, the order of the steps described above is the order in which the steps are performed. However, there may be more steps performed before, after, or between any of the steps of the method described above.

[0008] As used herein, the term “aerosol generating system” may be used to describe a system configured to generate an aerosol. The aerosol may be for inhalation by the user. An aerosol generating system may comprise an aerosol generator and a cartridge. The aerosol generator may include a power supply. The cartridge may include an aerosol-forming substrate.

[0009] As used herein, the term “aerosol generating element” may be used to describe one or more elements configured to generate an aerosol or vapor from an aerosol-forming substrate. An aerosol generating element, or one or more of the elements forming an aerosol generating element, may be connected to a power source; that is, an aerosol generating system may include a power source configured to supply power to the aerosol generating element.

[0010] As used herein, the term "aerosol-forming substrate" is used to mean a substrate having the ability to release volatile compounds capable of forming an aerosol. The volatile compounds may be released by heating the aerosol-forming substrate. The aerosol generated from the aerosol-forming substrate of the aerosol generating system according to the present invention may be visible or invisible, and may also include vapor (e.g., particulate matter in gaseous state of a substance that is normally liquid or solid at room temperature), as well as gas and liquid droplets of condensed vapor.

[0011] As used herein, the term "flow rate" can be used to describe any parameter indicating the flow rate through an aerosol generating system. For example, the defined "flow rate" can be one or more of pressure, flow velocity, temperature, mass flow rate or volume flow rate. Thus, the defined "flow sensor" can detect one or more of pressure, flow velocity, temperature, mass flow rate or volume flow rate.

[0012] As used herein, the term "smoking detection system" can refer to a system comprising a flow sensor.

[0013] As used herein, the term "airflow" may be used to refer to a flow of only air, or may be used to refer to a flow of air combined with aerosol droplets.

[0014] As used herein, the term "droplet" can be used to mean droplets or particles. That is, the term "droplet" can refer to liquid droplets. Alternatively, or additionally, the term "droplet" can refer to solid particles.

[0015] The flow sensor can include an electromechanical device, or a mechanical device, or an optical device, or an optomechanical device, or a microelectromechanical system (MEMS)-based sensor, an acoustic sensor, or any combination of the foregoing.

[0016] As used herein, the term “fumification” is used to describe inhalation by a user that creates an airflow through an aerosol generating system. The start of fumification is defined by the point at which a flow sensor detects that the flow rate is greater than the fumification start threshold, and the end of fumification is defined by the point at which a flow sensor detects that the flow rate has decreased to below the fumification end threshold.

[0017] As used herein, the term “predetermined” is used to mean that it is determined prior to the start of smoking.

[0018] According to a first aspect of the present invention, a method for controlling aerosol generation includes increasing the power supplied to an aerosol generating element when a flow sensor detects that the airflow rate is greater than a third threshold, before detecting that the airflow rate is less than a smoke extraction termination threshold. That is, the power supplied to the aerosol generating element may be increased two or more times during smoke extraction, depending on the smoke extraction profile. This is advantageous as it enables the aerosol generating system to deliver sufficient aerosol to the user during smoke extraction with a complex smoke extraction profile. In this context, the term “complex smoke extraction profile” is used to mean a smoke extraction profile that has at least one local maximum when plotting a graph of flow rate against time. For example, this step may mitigate potential problems in an exemplary smoke extraction profile that includes the following steps: • Stage 1: The user extracts smoke from the system and increases the detected airflow rate from zero to the first maximum flow rate. • Stage 2: Next, the detected flow rate is reduced to a first local minimum flow rate that is greater than the smoke extraction termination threshold. • Stage 3: Next, the flow rate increases to the second maximum flow rate. • Stage 4: Next, the flow rate decreases to below the smoke extraction termination threshold, indicating that smoke extraction has ended.

[0019] If the power supplied to the aerosol generating element is reduced between stages 2 and 3 of smoke extraction and not increased again, the user may become frustrated with the delivery of an inadequate aerosol during stages 3 and 4 of smoke extraction. In the method according to the present invention, the power supplied to the aerosol generating element may be increased during stage 3. Thus, the user may be delivered an appropriate aerosol during stages 3 and 4.

[0020] The power P0 may be zero. Advantageously, this can save power. This could mean that the aerosol generating system does not need to be recharged frequently.

[0021] Alternatively, the power P0 may be a non-zero power. Advantageously, this may allow the system to deliver the appropriate aerosol more quickly in response to detected smoke extraction.

[0022] Power P2 may be zero. Advantageously, this can save power. This could mean that the aerosol generating system does not need to be recharged frequently.

[0023] Alternatively, the power P2 may be a non-zero power. Advantageously, this may allow the system to deliver the appropriate aerosol more quickly in response to the detected flow rate being greater than a third threshold.

[0024] The third threshold can be a predetermined second ratio of the first maximum flow rate. The predetermined second ratio must be greater than the predetermined first ratio so that the third threshold is greater than the second threshold.

[0025] Alternatively, the third threshold may be a predetermined multiple of the second threshold. This predetermined multiple must be greater than 1, such that the third threshold is greater than the second threshold. The predetermined multiple does not need to be an integer.

[0026] The first threshold may also be the first constant.

[0027] The smoke inhalation termination threshold can be the smoke inhalation termination constant.

[0028] The step of increasing the power supplied to the aerosol generating element from power P0 to at least power P1 may include increasing the power supplied to the aerosol generating element to power PX, where PX is greater than or equal to power P1. If the flow sensor detects that the airflow rate is greater than a third threshold before detecting that the airflow rate is less than the smoke extraction termination threshold, the step of increasing the power supplied to the aerosol generating element may include increasing the power supplied to the aerosol generating element to power P3, where P3 is less than or equal to PX. A P3 less than PX may be advantageous for a typical smoke extraction profile where the first maximum flow rate is the maximum flow rate during smoke extraction.

[0029] The method may include a step of increasing the power supplied to the aerosol generating element when the flow sensor detects that the airflow rate is greater than a third threshold, before detecting that the airflow rate is less than the smoke extraction termination threshold, and then reducing the power supplied to the aerosol generating element to power P4 when the flow sensor detects that the airflow rate is less than the smoke extraction termination threshold.

[0030] Power P4 may be zero. Advantageously, this can save power. This could mean that the aerosol generating system does not need to be recharged frequently.

[0031] Alternatively, power P4 does not have to be zero. Advantageously, this may allow the system to deliver the appropriate aerosol more quickly in response to the next detected smoke extraction.

[0032] The power P4 does not have to be zero, and the method may further include the step of reducing the power supplied to the aerosol generating element from power P4 to zero, after the step of reducing the power supplied to the aerosol generating element to power P4 when the flow sensor detects that the airflow rate is less than the smoke extraction termination threshold. Reducing the power supplied to the aerosol generating element from power P4 to zero may occur if no further smoke extraction is detected within a given time interval, for example, within 5 minutes or 3 minutes after the power supplied to the aerosol generating element has been reduced to power P4. In other words, reducing the power supplied to the aerosol generating element from power P4 to zero may occur if no flow rate greater than the first threshold is detected within a given time interval after the power supplied to the aerosol generating element has been reduced to power P4.

[0033] The process of increasing the power supplied to an aerosol generating element from power P0 to at least power P1 may include increasing the power from power P0 to at least power P1 substantially immediately. That is, the power may be increased from power P0 to at least power P1 over a period of substantially equal zero. On a plot of heating power on the y axis versus time on the x axis, this may be represented by a vertical, or substantially vertical, line from power P0 to at least power P1. For example, the term “substantially immediate” may be used to mean that the power may be increased from power P0 to at least power P1 within 0.1 seconds. Advantageously, increasing the power supplied to an aerosol generating element substantially immediately may result in faster aerosol generation and less lag for the user.

[0034] Alternatively, the process of increasing the power supplied to an aerosol generating element from power P0 to at least power P1 may include gradually increasing the power from power P0 to at least power P1. That is, the power may be gradually increased from power P0 to at least power P1 over a period of time. The longer the period, the more gradually the power increase will be. On a plot of heating power on the vertical axis versus time on the horizontal axis, this may be represented by a line with a positive mean slope from power P0 to at least power P1. The slope of the line may be constant or not. That is, the rate of change of power may be constant or not. For example, the term “gradually” may be used to mean that the power may be increased from power P0 to at least power P1 over a period of 0.1 seconds to 1 second, or 0.2 seconds to 0.6 seconds, or 0.2 seconds to 0.4 seconds.

[0035] The step of reducing the power supplied to the aerosol generating element to power P2 may include reducing the power supplied to the aerosol generating element from at least power P1 to power P2.

[0036] The process of reducing the power supplied to the aerosol generating element to power P2 may include reducing the power supplied to the aerosol generating element to power P2 substantially immediately. That is, the power may be reduced to power P2 over a period of substantially zero. On a plot of heating power on the vertical axis versus time on the horizontal axis, this may be represented by a vertical or substantially vertical line up to power P2. For example, the term “substantially immediate” may be used to mean that the power may be increased to power P2 within 0.1 seconds.

[0037] Alternatively, the process of reducing the power supplied to the aerosol generating element to power P2 may include gradually reducing the power supplied to the aerosol generating element to power P2. That is, the power may be reduced over a period of time that is not equal to zero. In other words, the power may be gradually reduced to power P2 over a period of time. The longer the period, the more gradually the power reduction will be. On a plot of heating power on the vertical axis versus time on the horizontal axis, this may be represented by a line with a negative mean slope down to power P2. The slope of the line may be constant or not. For example, the term “gradually” may be used to mean that the power may be reduced to power P2 within a period of 0.1 seconds to 1 second, or 0.2 seconds to 0.6 seconds, or 0.2 seconds to 0.4 seconds, after the flow sensor detects that the airflow rate is less than a second threshold.

[0038] The method may include a step of increasing the power supplied to the aerosol generating element from at least P1 to P5, after the step of increasing the power supplied to the aerosol generating element from power P0 to at least P1, but before the step of decreasing the power supplied to the aerosol generating element to power P2.

[0039] The power supplied to the aerosol generating element may be increased from at least power P1 to power P5, preferably substantially immediately after the step of increasing the power supplied to the aerosol generating element from power P0 to at least power P1. In this context, the term "substantially immediately" may be used to mean within 0.1 seconds.

[0040] Alternatively, the step of increasing the power supplied to the aerosol generating element from power P0 to at least power P1 may include increasing the power supplied to the aerosol generating element from power P0 to power P5, where power P5 is greater than power P1.

[0041] Advantageously, this can provide a burst of power near the start of smoke inhalation. High power near the start of smoke inhalation can lead to an early start of appropriate aerosol generation. This can provide good responsiveness to the user. This can also reduce the aerosol droplet size near the start of smoke inhalation. Power P5 may be predefined. Power P5 can depend on a number of factors, including but not limited to the aerosol generating element, the type of aerosol forming substrate, the amount of aerosol to be formed, and the droplet size required for the aerosol. After the initial burst of power, it is preferable that the power decrease to, for example, power P1.

[0042] Supplying power to an aerosol generating element may include supplying an electric current pulse to the aerosol generating element.

[0043] Increasing or decreasing the power supplied to the aerosol generating element may include changing the frequency or magnitude of the current pulse supplied to the aerosol generating element, or both.

[0044] According to a second aspect of the present invention, an aerosol generating system is provided. The system comprises an aerosol generating element and a flow path configured to allow an airflow to pass through the aerosol generating element. The system further comprises a flow sensor configured to detect the airflow, the airflow indicating that the user is inhaling smoke, and a power supply for supplying power to the aerosol generating element. The system further comprises an electrical circuit for controlling the power supply from the power supply to the aerosol generating element, the electrical circuit being arranged to carry out the method according to the first aspect of the present invention.

[0045] According to a third aspect of the present invention, an electrical circuit for an aerosol generating system is provided, the electrical circuit being arranged to carry out the method according to the first aspect of the present invention.

[0046] According to a fourth aspect of the present invention, a computer program is provided that, when executed on a programmable electrical circuit for an aerosol generation system, causes the programmable electrical circuit to carry out the method according to the first aspect of the present invention.

[0047] According to a fifth aspect of the present invention, a computer-readable storage medium is provided, on which a computer program according to a fourth aspect of the present invention is stored.

[0048] A sixth aspect of the present invention provides a method for controlling aerosol generation in an aerosol generating system. The system comprises an aerosol generating element and a housing having an air intake and an air outlet. A flow path is defined through the housing from the air intake to the air outlet, and the flow path provides an airflow through the aerosol generating element when a user inhales smoke in the system. The system further comprises a flow sensor configured to detect the airflow, which indicates that a user is inhaling smoke. The method includes increasing the power supplied to the aerosol generating element from power p20 to at least power p21 when the flow sensor detects that the flow rate of the airflow is greater than a first threshold t21. The method is provided under the following conditions: The flow sensor detects that the airflow rate is less than a second threshold t22, where the second threshold t22 is a predetermined flow rate or indicates that it is, or The flow sensor detects that the airflow rate is less than a third threshold t23, and that the third threshold t23 is a predetermined percentage of the maximum detectable airflow rate. The process further includes detecting that the airflow rate is greater than a first threshold t21 as either of the above occurs first, and then reducing the power supplied to the aerosol generating element to power p22, where power p22 is less than power p21.

[0049] The second threshold t22 and the third threshold t23 are both greater than zero.

[0050] Advantageously, reducing the power supplied to the aerosol-generating element before the flow rate drops to zero can reduce the amount of condensation that can form in the system, which can affect liquid leakage.

[0051] Advantageously, by reducing the power supplied to the aerosol generating element as either condition occurs first, the power can be reduced at a greater flow rate for smoke extraction with a larger maximum detectable flow rate. However, regardless of the maximum detectable flow rate of the smoke extraction, the second threshold t22 provides the minimum flow rate at which the power supplied to the aerosol generating element is reduced.

[0052] Power p22 may be zero.

[0053] The process of increasing the power supplied to an aerosol generating element from power p20 to at least power p21 may include increasing the power from power p20 to at least power p1 substantially immediately. That is, the power may be increased from power p20 to at least power p21 over a period of substantially equal zero. On a plot of heating power on the vertical axis versus time on the horizontal axis, this may be represented by a vertical or substantially vertical line from power p20 to at least power p21. For example, the term “substantially immediate” may be used to mean that the power may be increased from power p20 to at least power p21 within 0.1 seconds.

[0054] Alternatively, according to a sixth embodiment, the step of increasing the power supplied to the aerosol generating element from power p20 to at least power p21 may include gradually increasing the power from power p20 to at least power p21. That is, the power may be gradually increased from power p20 to at least power p21 over a period of time. The longer the period, the more gradually the power increase will be. On a plot of heating power on the vertical axis versus time on the horizontal axis, this may be represented by a line with a positive mean slope from power p20 to at least power p21. The slope of the line may be constant or not. For example, the term “gradually” may be used to mean that the power may be increased from power p20 to at least power p21 over a period of 0.1 seconds to 1 second, or 0.2 seconds to 0.6 seconds, or 0.2 seconds to 0.4 seconds.

[0055] According to the sixth embodiment, the step of reducing the power supplied to the aerosol generating element to power p22 may include reducing the power supplied to the aerosol generating element from at least power p21 to power p22.

[0056] According to the sixth aspect, the step of reducing the power supplied to the aerosol generating element to power p22 may include reducing the power supplied to the aerosol generating element to power p22 substantially immediately. That is, the power may be reduced to power p22 over a period of substantially equal zero. On a plot of heating power on the vertical axis versus time on the horizontal axis, this may be represented by a vertical or substantially vertical line up to power p22. For example, the term “substantially immediate” may be used to mean that the power may be increased to power p22 within 0.1 seconds.

[0057] Alternatively, according to the sixth embodiment, the step of reducing the power supplied to the aerosol generating element to power p22 may include gradually reducing the power supplied to the aerosol generating element to power p22. That is, the power may be reduced over a period of time that is not equal to zero. That is, the power may be gradually reduced to power p22 over a period of time. The longer the period, the more gradually the power reduction occurs. On a plot of heating power on the vertical axis versus time on the horizontal axis, this may be represented by a line with a negative mean slope up to power p22. The slope of the line may be constant or not. For example, the term “gradually” may be used to mean that the power may be reduced to power p22 within a period of 0.1 seconds to 1 second, or 0.2 seconds to 0.6 seconds, or 0.2 seconds to 0.4 seconds, after the flow sensor detects that the airflow rate is less than a second threshold t22.

[0058] According to the sixth aspect, the method may include a step of increasing the power supplied to the aerosol generating element from at least power p21 to power p25, after the step of increasing the power supplied to the aerosol generating element from power p20 to at least power p21, but before the step of decreasing the power supplied to the aerosol generating element to power p22.

[0059] According to the sixth embodiment, the power supplied to the aerosol generating element may be increased from at least power p21 to power p25, preferably substantially immediately after the step of increasing the power supplied to the aerosol generating element from power p20 to power p21. In this context, the term “substantially immediately” may be used to mean within 0.1 seconds.

[0060] Alternatively, the step of increasing the power supplied to the aerosol generating element from power p20 to at least power p21 may include increasing the power supplied to the aerosol generating element from power p20 to power p25, where power p25 is greater than power p21.

[0061] This can provide a burst of power near the start of smoke inhalation. Such a burst of power near the start of smoke inhalation can lead to an early start of appropriate aerosol generation. This can provide good responsiveness to the user. This can also reduce the aerosol droplet size near the start of smoke inhalation. Power p25 may be predefined. Power p25 can depend on a number of factors, including but not limited to the aerosol generating element, the type of aerosol forming substrate, the amount of aerosol to be formed, and the droplet size required for the aerosol. After the initial burst of power, it is preferable that the power decrease to, for example, power p21.

[0062] According to the sixth aspect, supplying power to an aerosol generating element may include supplying an electric current pulse to the aerosol generating element.

[0063] According to the seventh aspect, an aerosol generating system is provided which is configured to carry out the method of the sixth aspect. The system comprises an aerosol generating element and a flow path configured to allow an airflow to pass through the aerosol generating element. The system further comprises a flow sensor configured to detect the airflow, which indicates that the user is inhaling smoke, and a power supply for supplying power to the aerosol generating element. The system further comprises an electrical circuit for controlling the power supply from the power supply to the aerosol generating element, the electrical circuit being configured to carry out the method of the sixth aspect.

[0064] According to the eighth aspect, an electrical circuit for an aerosol generating system is provided, the electrical circuit being arranged to carry out the method of the sixth aspect.

[0065] According to the ninth aspect, a computer program is provided that, when executed on a programmable electrical circuit for an aerosol generating system, causes the programmable electrical circuit to perform the method of the sixth aspect.

[0066] According to the tenth aspect, a computer-readable storage medium is provided having a computer program that, when executed on a programmable electrical circuit for an aerosol generating system, causes the programmable electrical circuit to perform the method of the sixth aspect.

[0067] According to the eleventh aspect, a method is provided for controlling aerosol generation in an aerosol generating system. The system comprises an aerosol generating element, a housing having an air intake and an air outlet, and a flow path defined through the housing from the air intake to the air outlet, the flow path providing an airflow through the aerosol generating element when a user inhales smoke in the system. The system further comprises a flow sensor configured to detect the airflow, indicating that the user is inhaling smoke. The method according to the eleventh aspect consists of the following time-series steps: The process involves increasing the power supplied to the aerosol generating element from power p30 to at least power p31 when the flow sensor detects that the airflow rate is greater than a first threshold t31, A process in which, when a flow sensor detects that the airflow rate is less than a second threshold t32, the power supplied to the aerosol generating element is reduced to power p32, wherein power p32 is less than power p31. - A process to increase the power supplied to an aerosol generating element to power p33 if, within a predetermined time interval after the flow sensor detects that the airflow rate is less than a second threshold t32, the flow sensor detects that the airflow rate is greater than a third threshold t33, wherein the third threshold t33 is less than the second threshold t32. The process includes any of the following steps: if the flow sensor detects that the airflow rate is less than a fourth threshold t34, and the fourth threshold t34 is less than a second threshold t32, and the time difference between the time at which the airflow rate is detected to be less than the second threshold t32 and the time at which the airflow rate is detected to be less than the fourth threshold t34 is less than a fifth threshold t35, then increasing the power supplied to the aerosol generating element to power p34.

[0068] According to the eleventh embodiment, the third threshold t33 is smaller than the second threshold t32, and the fourth threshold t34 is smaller than the second threshold t32. Advantageously, this allows the aerosol generating system to deliver sufficient aerosol to the user during a slowly fading inhalation.

[0069] According to the eleventh embodiment, the second threshold t32 is a flow rate that is a predetermined first ratio of the first maximum flow rate sensed by the flow sensor, or may indicate such a flow rate.

[0070] According to the eleventh embodiment, the flow sensor can detect the flow rate continuously or intermittently.

[0071] According to the eleventh embodiment, the flow sensor may detect the flow rate for a first predetermined period after the flow sensor has detected that the flow rate has decreased to less than a second threshold t32. The flow sensor may then compare this detected flow rate for the first predetermined period after the detection that the flow rate has decreased to less than the second threshold t32 with a third threshold t33.

[0072] According to the eleventh aspect, the flow sensor can regularly detect the flow rate through the entire smoke intake, meaning that the flow rate is detected every period tp3. The flow sensor can compare the nth detected flow rate to a third threshold t33 after it has detected that the flow rate has decreased to below a second threshold t32, where n is an integer greater than 1. Conveniently, this means that the nth flow rate is not compared to the third threshold until at least n-1 multiplied by period tp3 has elapsed since the flow sensor first detected that the flow rate has decreased to below the second threshold.

[0073] According to the eleventh aspect, any increase or decrease in the power supplied to the aerosol generating element may occur substantially immediately or in stages. As described with reference to the method of the sixth aspect in relation to the claimed invention, the term “in stages” may be used to mean within a period of 0.1 seconds to 1 second, or 0.2 seconds to 0.6 seconds, or 0.2 seconds to 0.4 seconds, and the term “substantially immediately” may be used to mean within 0.1 seconds.

[0074] According to the eleventh embodiment, power p32 may be zero. Power p33 may be a predetermined power. Power p34 may be a predetermined power. Powers p33 and p34 may be the same power. Alternatively, powers p33 and p34 may be different powers.

[0075] The eleventh embodiment of the method includes a step of increasing the power supplied to the aerosol generating element from at least p31 to p35, after the step of increasing the power supplied to the aerosol generating element from power p30 to at least p31, but before the step of decreasing the power supplied to the aerosol generating element to power p32.

[0076] According to the eleventh embodiment, the power supplied to the aerosol generating element may be increased from at least power p31 to power p35, preferably substantially immediately after the step of increasing the power supplied to the aerosol generating element from power p30 to at least power p31. In this context, the term “substantially immediate” may be used to mean within 0.1 seconds.

[0077] Alternatively, according to the eleventh embodiment, the step of increasing the power supplied to the aerosol generating element from power p30 to at least power p31 may include increasing the power supplied to the aerosol generating element from power p30 to power p35, where power p35 is greater than power p31.

[0078] This can provide a burst of power near the start of smoke inhalation. Such a burst of power near the start of smoke inhalation can lead to an early start of proper aerosol generation. This can reduce lag for the user. This can also reduce the aerosol droplet size near the start of smoke inhalation. Power p35 may be predefined. Power p35 can depend on a number of factors, including but not limited to the aerosol generating element, the type of aerosol forming substrate, the amount of aerosol to be formed, and the droplet size required for the aerosol. After the initial burst of power, it is preferable that the power decrease to, for example, power p31.

[0079] The eleventh embodiment of the method may further include the step of reducing the power supplied to the aerosol generating element to power p36 when, after either the step of increasing the power supplied to the aerosol generating element to power p33 or the step of increasing the power supplied to the aerosol generating element to power p34, the flow sensor detects that the airflow rate has decreased to less than the smoke extraction termination threshold t3e.

[0080] The power p36 may be zero. The smoke absorption termination threshold t3e can be the smoke absorption termination constant.

[0081] According to the eleventh embodiment, supplying power to an aerosol generating element may include supplying an electric current pulse to the aerosol generating element.

[0082] According to the twelfth aspect, an aerosol generating system is provided which is configured to carry out the method according to the eleventh aspect. The system comprises an aerosol generating element and a flow path configured to allow an airflow to pass through the aerosol generating element. The system further comprises a flow sensor configured to detect the airflow, which indicates that the user is inhaling smoke, and a power supply for supplying power to the aerosol generating element. The system further comprises an electrical circuit for controlling the power supply from the power supply to the aerosol generating element, the electrical circuit being configured to carry out the method according to the eleventh aspect.

[0083] According to a thirteenth aspect of the present invention, an electrical circuit for an aerosol generating system is provided, the electrical circuit being arranged to carry out the method according to the eleventh aspect.

[0084] According to the fourteenth aspect, a computer program is provided that, when executed on a programmable electrical circuit for an aerosol generating system, causes the programmable electrical circuit to perform the method according to the eleventh aspect.

[0085] According to the fifteenth aspect, a computer-readable storage medium is provided having a computer program that, when executed on a programmable electrical circuit for an aerosol generating system, causes the programmable electrical circuit to carry out the method according to the eleventh aspect.

[0086] According to a sixteenth aspect of the present invention, a method is provided for controlling aerosol generation in an aerosol generating system. The system comprises a data storage means and an aerosol generating element. The system further comprises a housing having an air intake and an air outlet, and a flow path defined through the housing from the air intake to the air outlet, the flow path providing an airflow that passes through the aerosol generating element when a user inhales smoke in the system. The system further comprises a flow sensor configured to detect the airflow, which indicates that a user is inhaling smoke. The method includes increasing the power supplied to the aerosol generating element from power p4x to at least power p41 when the flow sensor detects that the flow rate of the airflow is greater than a first threshold t41. The method further includes storing the measured values ​​measured by the flow sensor in the data storage means, and intermittently calculating an estimate of the remaining volume of smoke inhaled using the measured values ​​stored in the data storage means. The method further includes the step of reducing the power supplied to the aerosol generating element to power t42 when the estimated remaining volume of the smoke is less than a second threshold t42, where the second threshold t42 is a measured volume or an indication thereof.

[0087] Advantageously, the method of the sixteenth embodiment allows an approximate volume, referred to herein as the flushing volume of air, to pass through the aerosol generating system after the power supplied to the aerosol generating element has decreased. The second threshold t42 is the flushing volume or indicates it.

[0088] According to the sixteenth embodiment, the second threshold t42 may be a predetermined value.

[0089] According to the sixteenth aspect, the second threshold t42 is a volume that is approximately equal to or indicates to be the internal volume of the flow passage in the mouthpiece of the aerosol generating system. That is, if the airflow flows through the flow passage in the mouthpiece of the aerosol generating system, the flushing volume may, advantageously, be approximately equal to the volume of the flow passage in the mouthpiece. In this context, "approximately equal to the volume of the flow passage" may be used to mean within 1.5 to 0.5 times, or 0.75 to 1.25 times, or 0.9 to 1.1 times, or within 5 ml, 3 ml, or 1 ml of the flow passage volume.

[0090] According to the sixteenth embodiment, the second threshold t42 is a volume of 0.1 ml to 10 ml, or 0.1 ml to 5 ml, or 0.1 ml to 3 ml, or 0.1 ml to 1 ml, or 1 ml to 10 ml, or 1 ml to 5 ml, or may indicate such a volume.

[0091] The sixteenth embodiment of the method may include a step of reducing the power supplied to the aerosol generating element to power p42 when the estimated remaining volume of smoke is less than a second threshold t42, followed by a step of increasing the power supplied to the aerosol generating element to power p43. The step of increasing the power supplied to the aerosol generating element to power p43 may occur when the estimated remaining volume of smoke is greater than a third threshold t43, where the third threshold t43 is greater than the second threshold t42.

[0092] According to the sixteenth aspect, the flow sensor can measure values ​​continuously or intermittently.

[0093] According to the sixteenth aspect, the intermittent calculation of the estimated remaining volume of smoke can be performed by one or more of several methods.

[0094] As a first embodiment of the calculation method, the flow sensor may intermittently store volumetric flow rate values. In this context, "intermittently" means periodically, for example, over a period T. P It can be used to mean "each" or "one." Period T PFor example, it may be 0.01 seconds. For each of the second and subsequent stored values, the processor calculates the average rate of change A of the current flow rate c can be calculated. This average rate of change A of the current flow rate c is the current flow rate value Q c minus the previously stored flow rate value Q c-1 and then divided by the period T P can be estimated. Next, the processor can assume that this average rate of change A of the current flow rate c remains constant. This means that when the average rate of change A of the current flow rate c is negative, the remaining time T of the current smoking C is estimated to be equal to the negative of the current flow rate value Q c divided by the average rate of change A of the current flow rate c . The processor can calculate the estimated value of the remaining volume V of the current smoking c as -0.5 times the square of the current flow rate value Q c divided by the average rate of change A of the current flow rate c . Of course, this calculation only provides a reasonable estimate of the remaining volume V and the remaining time T of the current smoking such that the remaining volume V c is positive when the average rate of change A of the current flow rate c is negative. The processor may ignore all such remaining volumes V c that return negative values. The processor may not calculate the estimated value until the average rate of change A of the current flow rate C is calculated. In particular, the remaining time T of the current c need not be calculated to estimate the remaining volume V of the current c . In formula form, the first embodiment can be summarized as follows C is the remaining volume V of the current c need not be calculated. As another method, as a second embodiment, the average rate of change A of the current flow rate

Number

[0095] As another method, as a second embodiment, the average rate of change A of the current flow rate cQ is the flow rate value immediately following. c+1 The flow rate value Q stored immediately before c-1 After subtracting, period T p It can be estimated by dividing by Q. Naturally, this estimate is based on the flow rate value Q. c+1 It cannot be carried out until immediately after the measurement is taken. In formula form, the second embodiment can be summarized as follows:

number

[0096] Alternatively, in a third embodiment, nonlinear extrapolation of the flow rate may be used. Nonlinear extrapolation may use a predetermined polynomial that more accurately represents the change in flow rate of the smoke towards the end of a typical smoke extraction profile. Alternatively, nonlinear extrapolation may rely on previously stored measurements taken by a flow sensor during the current smoke extraction. For example, if the average rate of change of flow rate appears to be decreasing in each subsequent measurement taken near the end of the smoke extraction, a polynomial that more accurately estimates the change in flow rate for such smoke extractions may be selected, while a different polynomial may be selected for smoke extractions where the rate of change of flow rate is constant or increasing. Advantageously, this can more accurately estimate the change in flow rate towards the end of the smoke extraction and thus provide a better estimate of the remaining volume of smoke extraction.

[0097] According to the sixteenth aspect, the intermittent calculation of the estimated remaining volume of smoke may not begin until the flow sensor detects that the flow rate has decreased to below the estimated start threshold t4s. Alternatively, the intermittent calculation of the estimated remaining volume of smoke may not act until the flow sensor detects that the flow rate has decreased to below the estimated start threshold t4s, which means that the power supplied to the aerosol generating element does not change. The estimated start threshold t4s may be a predetermined percentage of the maximum flow rate detected. Advantageously, this can help avoid changing the power supplied to the aerosol generating element based on an inaccurately small estimate of the remaining volume of smoke. For example, if the flow rate decreases significantly after the maximum flow rate has been detected, the calculated estimate of the remaining volume of smoke may be too small compared to the actual remaining volume of smoke.

[0098] According to the sixteenth aspect, any increase or decrease in the power supplied to the aerosol generating element may occur substantially immediately or in stages. As described in relation to the claimed invention and with reference to the method of the sixth aspect, the term “in stages” may be used to mean within a period of 0.1 seconds to 1 second, or 0.2 seconds to 0.6 seconds, or 0.2 seconds to 0.4 seconds, and the term “substantially immediately” may be used to mean within 0.1 seconds.

[0099] The method of the sixteenth embodiment may include a step of increasing the power supplied to the aerosol generating element from at least power p41 to power p45, after the step of increasing the power supplied to the aerosol generating element from power p4x to at least power p41, but before the step of decreasing the power supplied to the aerosol generating element to power p42.

[0100] According to the sixteenth aspect, the power supplied to the aerosol generating element may be increased from at least power p41 to power p45, preferably substantially immediately after the step of increasing the power supplied to the aerosol generating element from power p4x to power p41. In this context, the term “substantially immediately” may be used to mean within 0.1 seconds.

[0101] Alternatively, the step of increasing the power supplied to the aerosol generating element from power p4x to at least power p41 may include increasing the power supplied to the aerosol generating element from power p4x to power p45, where power p45 is greater than power p41.

[0102] This can provide a burst of power near the start of smoke inhalation. Such a burst of power near the start of smoke inhalation can lead to an early start of appropriate aerosol generation. This can provide good responsiveness to the user. This can also reduce the aerosol droplet size near the start of smoke inhalation. Power p45 may be predefined. Power p45 can depend on a number of factors, including but not limited to the aerosol generating element, the type of aerosol forming substrate, the amount of aerosol to be formed, and the droplet size required for the aerosol. After the initial burst of power, it is preferable that the power decrease to, for example, power p41.

[0103] According to the sixteenth aspect, supplying power to an aerosol generating element may include supplying an electric current pulse to the aerosol generating element.

[0104] In another embodiment, an aerosol generating system is provided, configured to carry out the method of the sixteenth embodiment. The system comprises an aerosol generating element and a flow path configured to allow an airflow to pass through the aerosol generating element. The system further comprises a flow sensor configured to detect the airflow, the airflow indicating that the user is inhaling smoke, and a power supply for supplying power to the aerosol generating element. The system further comprises an electrical circuit for controlling the power supply from the power supply to the aerosol generating element, the electrical circuit being configured to carry out the method of the sixteenth embodiment.

[0105] In another embodiment, an electrical circuit for an aerosol generating system is provided, the electrical circuit being arranged to carry out the method of the sixteenth embodiment.

[0106] In another embodiment, a computer program is provided that, when executed on a programmable electrical circuit for an aerosol generating system, causes the programmable electrical circuit to perform the method of the sixteenth embodiment.

[0107] In another embodiment, a computer-readable storage medium is provided for storing a computer program that, when executed on a programmable electrical circuit for an aerosol generating system, causes the programmable electrical circuit to perform the method of the sixteenth embodiment.

[0108] The aerosol generation system may include an aerosol-forming substrate, and the aerosol generation element may include one or more elements configured to interact with the aerosol-forming substrate to generate an aerosol or vapor, for example, by adding aerosol droplets to an airflow to generate an aerosol.

[0109] The aerosol generating element may include mechanical devices such as a vibrating orifice transducer or a piezoelectric device. The aerosol generating element may include an electric heater including at least one heater element. At least one electric heating element may be arranged to heat the aerosol forming substrate to form an aerosol.

[0110] The aerosol generating element may include a single heating element. Alternatively, the aerosol generating element may include multiple heating elements, for example, two, three, four, five, six, or more. The heating elements (one or more) may be appropriately arranged to heat the aerosol-forming substrate most effectively.

[0111] The aerosol generating element may include at least one electrically heating element. Preferably, at least one electrically heating element includes an electrically resistant material. Suitable electrically resistant materials include, but are not limited to, semiconductors such as doped ceramics, conductive ceramics (e.g., molybdenum disilide), carbon, graphite, metals, alloys, and composite materials made of ceramic and metallic materials. Such composite materials may include doped ceramics or undoped ceramics. An example of a suitable doped ceramic is doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable metal alloys include stainless steel, constantan, nickel-containing, cobalt-containing, chromium-containing, aluminum-containing, titanium-containing, zirconium-containing, hafnium-containing, niobium-containing, molybdenum-containing, tantalum-containing, tungsten-containing, tin-containing, gallium-containing, manganese-containing, and iron-containing alloys, as well as nickel, iron, cobalt, stainless steel-based superalloys, Timetal®, iron-aluminum alloys, and iron-manganese-aluminum alloys. Timetal® is a registered trademark of Titanium Metals Corporation (1999 Broadway Suite 4300, Denver Colorado). In composite materials, the electrical resistive material may be embedded in, sealed in, or coated with an insulating material, depending on the required energy transfer dynamics and external physicochemical properties. The heating element may include a metallic, etched foil insulated between two layers of inert material. In that case, the inert material may include Kapton®, full-layer polyimide, or mica foil. Kapton® is a registered trademark of EIdu Pont de Nemours and Company (1007 Market Street, Wilmington, Delaware 19898, United States of America).

[0112] Alternatively, or additionally, the aerosol generating element may include an infrared heating element, a photon source, or an inductive heating element.

[0113] At least one electric heating element may take any suitable form. For example, at least one electric heating element may take the form of a heating blade.

[0114] At least one electric heating element may include a casing or substrate having different conductive parts or electrically resistant metal tubes. If the aerosol-forming substrate is a liquid provided in a container, the container may incorporate a disposable heating element.

[0115] At least one electric heating element may include a heating needle or rod that penetrates the center of the aerosol-forming substrate.

[0116] At least one electric heating element may include a disc-shaped (end) heater or a combination of a disc-shaped heater and a heating needle or rod.

[0117] At least one electric heating element may comprise a flexible material sheet arranged to surround or partially surround the aerosol-forming substrate. Other alternatives include heating wires or filaments, such as wires or heating plates made of Ni-Cr, platinum, tungsten, or alloys. Optionally, the heating elements may be placed within or on a rigid carrier material.

[0118] Alternatively, or additionally, the aerosol generating element may include a heating element, which includes a plurality of conductive filaments. As used herein, the term “filament” refers to an electrical path arranged between two electrical contacts. The filaments may be arbitrarily branched and diverged into several paths or filaments, or several electrical paths may merge into one path. The filaments may have a round, square, flat, or any other cross-section. The filaments may be arranged in a straight manner or in a curved manner.

[0119] The heating element may be, for example, an array of filaments arranged parallel to each other. Preferably, the filaments can form a mesh. The mesh may be woven or unwoven. The mesh may be formed using different types of woven or lattice structures. Alternatively, the conductive heating element may consist of an array of filaments or a fabric of filaments. The mesh, array, or fabric of conductive filaments may also be characterized by its ability to hold liquid.

[0120] In a preferred embodiment, a substantially flat heating element may be constructed from wires formed into a wire mesh. The mesh preferably has a plain weave design. The heating element is preferably a wire grill made from mesh flecks.

[0121] The filament of the heating element may be formed from any material having suitable electrical properties. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, conductive ceramics, carbon, graphite, metals, alloys, and composite materials made of ceramic and metallic materials.

[0122] Preferred materials for conductive filaments are stainless steel and graphite, with 300 series stainless steels such as AISI 304, 316, 304L, and 316L being more preferred. To improve control of the heating element's resistance, combinations of materials may be used for the conductive heating element. For example, a material with high resistivity may be combined with a material with low resistivity. This may be advantageous if one of the materials is more beneficial in terms of other respects, such as price, machinability, or other physical or chemical parameters. Advantageously, a substantially flat filament arrangement with increased resistance reduces parasitic losses. Advantageously, a heater with high resistance allows for more efficient use of battery energy.

[0123] The filament is preferably made of wire. The wire is preferably made of metal, and most preferably of stainless steel.

[0124] Conductive filaments can define gaps between them. These gaps can have a width of 10 to 100 micrometers. Preferably, the filaments create capillary action within the gaps so that the liquid that will be vaporized during use is drawn into the gaps, thereby increasing the contact area between the heating element and the liquid aerosol-forming substrate.

[0125] At least one heating element may heat the aerosol-forming substrate by conduction. The heating element may be in at least partial contact with the substrate or the carrier on which the substrate is deposited.

[0126] Heat from a heating element may be conducted to the substrate by means of a thermally conductive element.

[0127] At least one heating element may transfer heat to incoming ambient air drawn in through an electrically heated aerosol generating system during use, which then heats the aerosol-forming substrate by convection. The ambient air may be heated before passing through the aerosol-forming substrate.

[0128] If the aerosol-forming substrate is a liquid substrate, ambient air may first be drawn in through the substrate and then heated.

[0129] The aerosol-forming substrate may be a solid aerosol-forming substrate. Preferably, the aerosol-forming substrate contains a tobacco-containing material, which includes volatile tobacco-flavored compounds emitted from the substrate upon heating. The aerosol-forming substrate may also contain non-tobacco materials. The aerosol-forming substrate may contain both tobacco-containing and non-tobacco-containing materials. Preferably, the aerosol-forming substrate further contains aerosol-forming bodies. Suitable examples of aerosol-forming bodies include glycerin and propylene glycol.

[0130] The aerosol-forming substrate may be a liquid aerosol-forming substrate. The aerosol-generating system may include a liquid storage section. The liquid aerosol-forming substrate is preferably stored in the liquid storage section. The aerosol-generating element may include a capillary core that communicates with the liquid storage section. The aerosol-generating system may include a capillary core for holding liquid without having a liquid storage section. In that case, the capillary core may be pre-filled with liquid.

[0131] It is preferable to arrange the capillary core so as to be in contact with the liquid in the liquid storage portion. In this case, during use, the liquid is moved from the liquid storage portion to at least one electric heating element by capillary action within the capillary core. In one embodiment, the capillary core may have a first end and a second end, the first end extending into the liquid storage portion to be in contact with the liquid inside, and at least one electric heating element may be arranged to heat the liquid in the second end. When the heating element is activated, the liquid at the second end of the capillary core is vaporized by the heater to form supersaturated vapor. The supersaturated vapor is mixed with the airflow and carried in the airflow. As it flows, the vapor condenses to form an aerosol, which is carried toward the user's mouth. Heating elements combined with a capillary core may provide a rapid response because this arrangement may provide the heating element with a large surface area of ​​liquid. Therefore, the control of the heating element according to the present invention may depend on the structure of the arrangement of the capillary core.

[0132] The liquid substrate may be absorbed into any suitable absorbent plug or body, for example, a porous carrier material which may be made of foamed metal or plastic material, polypropylene, terylene, nylon fiber, or ceramic. The liquid substrate may be held within the porous carrier material before use of the electrically heated aerosol generating system, or alternatively, the liquid substrate material may be released into the porous carrier material during or immediately before use. For example, the liquid substrate may be provided in a capsule. Preferably, the capsule shell melts upon heating, releasing the liquid substrate into the porous carrier material. The capsule may optionally contain a solid in combination with the liquid.

[0133] If the aerosol-forming substrate is a liquid substrate, the liquid has physical properties, such as a boiling point suitable for use in an aerosol-generating system. If the boiling point is too high, at least one electric heating element will not be able to vaporize the liquid in the capillary wick; however, if the boiling point is too low, the liquid may vaporize without activating at least one electric heating element. Control of at least one electric heating element may depend on the physical properties of the liquid substrate. The liquid preferably contains tobacco-containing material, including volatile tobacco-flavoring compounds released from the liquid when heated. Alternatively or additionally, the liquid may contain non-tobacco materials. The liquid may contain water, solvents, ethanol, plant extracts, and natural or artificial flavors. The liquid preferably further contains an aerosol-forming element. Examples of suitable aerosol-forming elements are glycerin and propylene glycol.

[0134] The advantage of providing a liquid storage section is that a high level of hygiene can be maintained. The system structure can be made relatively simple by using a capillary core extending between the liquid and the electric heating element. The liquid has physical properties, including viscosity and surface tension, that allow the liquid to be carried through the capillary core by capillary action. The liquid storage section is preferably a container. The liquid storage section does not need to be refillable. Therefore, when the liquid in the liquid storage section is depleted, the aerosol generating system is replaced. Alternatively, the liquid storage section may be refillable. In that case, the aerosol generating system may be replaced after a certain number of refills of the liquid storage section. The liquid storage section is preferably arranged to hold liquid for a predetermined number of fume extractions.

[0135] The capillary core may have a fibrous or spongy structure. Preferably, the capillary core contains a bundle of capillaries. For example, the capillary core may contain multiple fibers or threads, or other microtubules. The fibers or threads may generally be arranged along the long axis of the aerosol generating system.

[0136] Alternatively, the capillary core may contain a sponge-like or foam-like material formed into a rod shape. The rod shape may extend along the long axis of the aerosol generating system. The core structure forms several small holes or tubes through which the liquid can move to the electrically heated element by capillary action. The capillary core may contain any suitable material or combination of materials. Examples of suitable materials include ceramic or graphite-based materials in the form of fibers or sintered powders. The capillary core may have any suitable capillary properties and porosity, such as combining different liquid physical properties such as density, viscosity, surface tension, and vapor pressure. The capillary properties of the core, in conjunction with the properties of the liquid, ensure that the core remains moist within the heating region. If the core dries out, overheating may occur, which can lead to liquid degradation.

[0137] During operation, the substrate may be completely housed within the aerosol generating system. In this case, the user can inhale through the mouthpiece of the electrically heated aerosol generating system. Alternatively, during operation, the substrate may be partially housed within the aerosol generating system. In this case, the substrate may form part of a separate article, and the user may inhale directly from the separate article.

[0138] The aerosol generation system is preferably an electrically heated aerosol generation system. The aerosol generation system is even more preferably an electrically heated smoking system.

[0139] The aerosol generation system includes a flow path, a portion of which may be called an aerosol formation chamber. In the aerosol formation chamber, an aerosol is formed from supersaturated vapor and subsequently delivered into the user's mouth. The air intake, air outlet, and chamber are preferably arranged to define a path for airflow from the air intake through the aerosol formation chamber to the air outlet, so as to deliver the aerosol to the air outlet and into the user's mouth. Condensation may form on the walls of the aerosol formation chamber. The amount of condensation may depend on the heating profile, particularly towards the end of the smoke extraction process.

[0140] The housing of the aerosol generating system is preferably elongated. The structure of the housing, including the surfaces available for condensation formation, will affect the aerosol properties and whether or not there is liquid leakage from the aerosol generating system. The housing may consist of a shell and a mouthpiece. In that case, all components may be contained in either the shell or the mouthpiece. The housing may contain any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of these materials, or thermoplastic resins suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably light and not brittle. The material of the housing may affect the amount of condensation formed in the housing, which in turn will affect liquid leakage from the system.

[0141] The aerosol generating system is preferably portable. The aerosol generating system can be a smoking system and may be comparable in size to a conventional cigar or cigarette. The total length of the smoking system may be approximately 30 mm to 150 mm. The outer diameter of the smoking system may be approximately 5 mm to 30 mm.

[0142] Two or more of the methods described herein may be used in combination. For example, the fume extraction termination threshold of the method of the first embodiment may be calculated using the method of the sixteenth embodiment. That is, the fume extraction termination threshold of the first embodiment may be equal to the flushing volume of the sixteenth embodiment.

[0143] Two or more of the methods described herein may be provided as different operating modes in a single aerosol generating system. Users may select which method to implement using a user interface.

[0144] Features described in relation to one embodiment described herein may be applicable to another embodiment described herein. It will be obvious to those skilled in the art that features described in relation to one embodiment are applicable to another embodiment.

[0145] Herein, for illustrative purposes only, the present invention will be further explained with reference to the following attached drawings. [Brief explanation of the drawing]

[0146] [Figure 1] Figure 1 is a schematic diagram of the aerosol generation system. [Figure 2] Figure 2 shows plots of airflow rate over time and heating power over time in a known aerosol generation system that implements a known method for controlling aerosol generation. [Figure 3] Figure 3 shows plots representing the airflow rate over time and the heating power over time in the aerosol generation system according to the present invention. [Figure 4] Figure 4 shows plots indicating the airflow rate over time and the heating power over time in the aerosol generation system according to the present invention. [Figure 5] Figure 5 shows plots indicating the airflow rate over time and the heating power over time in the aerosol generation system according to the present invention. [Figure 6] Figure 6 shows plots representing the airflow rate over time and the heating power over time in an aerosol generation system according to the sixth embodiment described herein. [Figure 7] Figure 7 shows plots of airflow rate over time and heating power over time in an aerosol generation system according to the eleventh embodiment described herein. [Figure 8] Figure 8 shows plots of airflow rate over time and heating power over time in an aerosol generation system according to the sixteenth embodiment described herein. [Modes for carrying out the invention]

[0147] Figure 1 is a schematic diagram of an aerosol generating system. The system 100 comprises two main components: a cartridge 102 and a control unit 104. The connection terminal 106 of the cartridge 102 is detachably connected to the corresponding connection terminal 108 of the control unit 104. The aerosol generating system 100 is portable and is comparable in size to a conventional cigar or cigarette.

[0148] The control unit 104 houses a battery 110 (which in this embodiment is a rechargeable lithium-ion battery) and a control circuit 112. The control circuit 112 includes a smoke detection system 111.

[0149] The cartridge 102 includes a housing 114 that contains an atomizing assembly 116 and a liquid storage compartment 118. The liquid storage compartment contains a capillary material immersed in a liquid aerosol-forming substrate. In this example, the aerosol-forming substrate contains 39 wt percent glycerin, 39 wt percent propylene glycol, 20 wt percent water and flavoring agent, and 2 wt percent nicotine. The capillary material is a material that actively carries the liquid from one end to the other and may be made from any suitable material. In this example, the capillary material is made from polyester.

[0150] In this embodiment, the atomizing assembly includes a plurality of conductive heater filaments that form an electrically heated mesh heating element. When the cartridge 102 is connected to the control unit 104, the power supply 110 is electrically connected to the mesh heating element. The airflow passage extends from the air intake 122 through the atomizing assembly 116 and through the cartridge to the opening 124 at the mouth end inside the housing 114.

[0151] The system is configured to allow the user to draw an aerosol into their mouth by inhaling through the opening 124 at the mouth end of the cartridge 102. When in operation, as the user inhales through the mouth end opening 124, air is drawn through the airflow passage from the air intake 122. The smoke detection system 111 detects the airflow through the airflow passage and activates the atomizing assembly 116. The control circuit 112 controls the power supply from the power supply 110 to the atomizing assembly 116. Air flows through the atomizing assembly 116. The atomizing assembly 116 generates vapor that is mixed into the airflow passing through the airflow passage. The amount and characteristics of the vapor generated by the atomizing assembly 116 are at least partially controlled by the power supplied to the atomizing assembly 116 from the power supply 110. The air and the mixed vapor, or aerosol, flow into the user's mouth through the mouth end opening 124.

[0152] Figure 1 shows an example of an electrically heated aerosol generating system that may be used in the present invention. However, many other examples can be used in conjunction with the present invention. The present invention can be used in any electrically heated aerosol generating system comprising an aerosol generating element powered by a power source under the control of an electrical circuit. For example, the system does not have to be a smoking system. For example, the aerosol-forming substrate may be a fixed substrate rather than a liquid substrate. Alternatively, this aerosol-forming substrate may be in the form of another substrate such as a gel or paste. The aerosol-forming element can take any suitable form. The overall shape and size of the housing are modifiable, and the housing may comprise a separate shell and mouthpiece. Other variations are, of course, also possible.

[0153] In the embodiment shown in Figure 1, the control circuit 112, including the smoke extraction detection system 111, is programmable to control the power supply to the mesh heating element. This, in turn, affects the heating profile, which can influence the characteristics of the vapor, or aerosol. The term “heating profile” refers to a graphical representation of the power supplied to the heating element (or another similar measurement, e.g., the heat generated by the heating element) over the time taken for smoke extraction. However, if the control circuit 112 and the smoke extraction detection system 111 are wired together to control the power supply to the heating element, the aerosol generating system may function in much the same way. Again, this can affect the heating profile, and then the droplet size of the aerosol.

[0154] Figure 2 is a plot showing the airflow rate and heating power over time in a known aerosol generation system that implements known methods for controlling aerosol generation.

[0155] Figure 2 is a plot showing airflow rate 201 and heating power 203 on the vertical axis and time 205 on the horizontal axis. Airflow rate 201 is shown by a solid line, and heating power 203 is shown by a dotted line. Airflow rate is sensed by a smoke extraction detection system, such as the smoke extraction detection system 111 in Figure 1. Heating power, measured in watts, is the power supplied from the power source to the heating element under the control of an electrical circuit, such as the control circuit 112 in Figure 1. Figure 2 shows a single smoke extraction by a user in an electrically heated aerosol generation system, such as the one shown in Figure 1.

[0156] As shown in Figure 2, in this embodiment, the airflow rate for smoke extraction is illustrated as having the shape of a normal or Gaussian distribution. The airflow rate starts at zero, increases gradually up to a maximum of 201max, and then decreases back to zero. However, the airflow rate does not usually have a strict Gaussian distribution. In all cases, however, the airflow rate during smoke extraction increases from zero to a maximum, and then decreases from a maximum to zero. The region below the airflow rate curve represents the total air volume for that smoke extraction.

[0157] When the smoke detection system detects that the airflow rate 201 has increased to a threshold 201a at time 205a, the electrical circuit controls the power to turn on the heating element, directly increasing the heating power 203 from zero to power 203a. When the smoke detection system detects that the airflow rate 201 has decreased back to a threshold 201a at time 205b, the electrical circuit controls the power to turn off the heating element, immediately decreasing the heating power 203 from power 203a to zero. Between time 205a and time 205b, the smoke detection system detects that the airflow rate remains above the threshold 201a, and the heating power to the heating element is maintained at power 203a. Therefore, the heating period is from time 205b to 205a.

[0158] In the embodiment shown in Figure 2, the airflow threshold for turning on the heating element is the same as the airflow threshold for turning it off. The advantage of the arrangement in Figure 2 is the simplification of the design. However, this arrangement presents a possibility of overheating towards the end of the fume extraction, such as in the area circled 207 in Figure 2. Furthermore, if the fume extraction flow rate increases again after the power supplied to the heater has decreased to zero at time 205b, the heater will remain without power, and after time 205b, the user may become frustrated with improper aerosol delivery.

[0159] Figure 3 includes two plots. One plot shows airflow rate 301 on the vertical axis and time 305 on the horizontal axis, while the other plot shows heating power 303 on the vertical axis and time 305 on the horizontal axis. The time 305 shown in both plots is the same time. That is, the plots in Figure 3 show the airflow rate and heating power for the same smoke extraction. Airflow rate 301 is shown by a solid line, and heating power 303 is shown by a dotted line. Airflow rate is measured in volume per unit time, generally in cubic centimeters per second. Airflow rate is sensed by a smoke extraction detection system, such as the smoke extraction detection system 111 in Figure 1. Heating power is the power supplied from the power source to the heating element under the control of an electrical circuit, such as the control circuit 112 in Figure 1. Figure 3 shows a single smoke extraction by a user in an electrically heated aerosol generation system, such as the one shown in Figure 1.

[0160] As can be seen in Figure 3, in this embodiment, the smoke extraction profile is more complex than the smoke extraction profile shown in Figure 2. In this embodiment, the airflow rate 301 increases from zero to a first maximum flow rate 301max1. Next, the airflow rate decreases to a flow rate 301min1. Then, the airflow rate increases to a second maximum flow rate 301max2. Next, the airflow rate decreases to zero.

[0161] When the smoke detection system detects that the airflow rate 301 has increased to a threshold 301a at time 305a, the electrical circuit controls the power to turn on the heating element and substantially immediately increases the heating power 303 from zero to power 303a. When the smoke detection system detects that the airflow rate 301 has decreased to a threshold 301b at time 305b, the electrical circuit controls the power to turn off the heating element and substantially immediately decreases the heating power 303 from power 303a to zero. Between time 305a and time 305b, the heating power to the heating element is maintained at power 303a.

[0162] When the smoke detection system then senses that the airflow rate 301 has increased to a threshold 301c at time 305c, the electrical circuit controls the power to turn on the heating element, substantially instantly increasing the heating power 303 from zero to power 303c. When the smoke detection system senses that the airflow rate 301 has decreased to a threshold 301d at time 305d, the electrical circuit controls the power to turn off the heating element, substantially instantly decreasing the heating power 303 from power 303c to zero. Between time 305c and time 305d, the heating power to the heating element is maintained at power 303c.

[0163] In the embodiment shown in Figure 3, threshold 301a is a predetermined constant, and threshold 301d is another predetermined constant for smoke extraction termination. Threshold 305d is less than threshold 301a. Threshold 301b is 50% of 301max1, and threshold 301c is 65% of 301max1. Powers 303a and 303c are equal.

[0164] Figure 4 contains two plots. The first plot in Figure 4 shows the same smoke extraction profile as shown in Figure 3. This is copied onto Figure 4 only for comparison with the second plot in Figure 4. The second plot shows heating power 403 on the vertical axis and time 405 on the horizontal axis. The time shown in both plots is the same time. That is, the plots in Figure 4 show the airflow rate and heating power for the same smoke extraction. The airflow rate 301 is shown by a solid line, and the heating power 403 is shown by a dotted line. The airflow rate is sensed by a smoke extraction detection system, such as the smoke extraction detection system 111 in Figure 1. The heating power is the power supplied from the power source to the heating element under the control of an electrical circuit, such as the control circuit 112 in Figure 1. Figure 4 shows a single smoke extraction by a user in an electrically heated aerosol generating system, such as the one shown in Figure 1.

[0165] At time 305z, the user presses a button on the aerosol generation system. In response, the electrical circuit controls the power to turn on the heating element and increases the heating power to the heating element to power level 403z. As shown in Figure 4, the user presses the button immediately after the start of smoke extraction in the system. However, there are cases where the user presses the button before the system starts smoke extraction, and power is supplied at power level 403z before the airflow increases. In this embodiment, if the user presses the button, but the smoke extraction detection system does not detect an airflow exceeding threshold 301a within 10 seconds of the user pressing the button, the power supplied to the heating element may be reduced and returned to zero.

[0166] When the smoke extraction detection system senses that the airflow rate 301 has increased to a threshold 301a at time 305a, the electrical circuit controls the power to the heating element to immediately increase the heating power 403 from 403z to power 403a. The power supplied to the heating element is held at this level for a short period of time relative to the average smoke extraction time, approximately 0.2 seconds, before decreasing to power level 403x at time 305x. This provides an initial burst of power towards the start of smoke extraction.

[0167] When the smoke detection system detects that the airflow rate 301 has decreased to a threshold 301b at time 305b, the electrical circuit controls the power to turn off the heating element, reducing the heating power 403 from power 403x to zero. As shown in Figure 4, this power reduction occurs gradually at a constant rate between times 305b and 305b2.

[0168] When the smoke detection system then detects that the airflow rate 301 has increased to a threshold 301c at time 305c, the electrical circuit controls the power to turn on the heating element and immediately increases the heating power 403 from zero to power 403c. When the smoke detection system detects that the airflow rate 301 has decreased to a threshold 301d at time 305d, the electrical circuit controls the power to turn off the heating element and immediately decreases the heating power 403 from power 403c to zero. Between time 305c and time 305d, the heating power to the heating element is maintained at power 403c.

[0169] In the embodiment shown in Figure 4, threshold 301a is a predetermined constant, and threshold 301d is another predetermined constant for the termination of smoke extraction. Threshold 305d is smaller than threshold 301a. Threshold 301b is 50% of 301max1, and threshold 301c is 65% of 301max1. Power 403a is greater than power 403x, power 403x is greater than power 403c, and power 403c is greater than power 403z.

[0170] Figure 5 includes two plots. One plot shows airflow rate 501 on the vertical axis and time 505 on the horizontal axis, while the other plot shows heating power 503 on the vertical axis and time 505 on the horizontal axis. The time 505 shown in both plots is the same time. That is, the plots in Figure 5 show the airflow rate and heating power for the same smoke extraction. Airflow rate 501 is shown by a solid line, and heating power 503 is shown by a dotted line. Airflow rate is sensed by a smoke extraction detection system, such as the smoke extraction detection system 111 in Figure 1. Heating power is the power supplied from the power source to the heating element under the control of an electrical circuit, such as the control circuit 112 in Figure 1. Figure 5 shows a single smoke extraction by a user in an electrically heated aerosol generation system, such as the one shown in Figure 1.

[0171] As can be seen in Figure 5, in this embodiment, the smoke extraction profile is more complex than the smoke extraction profile shown in Figure 3. In this embodiment, the airflow rate 501 increases from zero to a first maximum flow rate 501max1. Next, the airflow rate experiences another local maximum 501maxz before decreasing to a local minimum flow rate 501min1. Next, the airflow rate increases to another local maximum flow rate 501max2 before decreasing to another local minimum flow rate 501min2. The airflow rate then increases to another local maximum 501max3 before decreasing to zero. In Figure 5, the flow rate 501max2 is greater than 501max1, 501max1 is greater than 501maxz, 501maxz is greater than 501min3, 501min3 is greater than 501min1, and 501min1 is greater than 501min2.

[0172] When the smoke detection system detects that the airflow rate 501 has increased to a threshold 501a at time 505a, the electrical circuit controls the power to turn on the heating element, directly increasing the heating power 503 from zero to power 503a. When the smoke detection system detects that the airflow rate 501 has decreased to a threshold 501b at time 505b, the electrical circuit controls the power to the heating element, immediately decreasing the heating power 503 from power 503a to 503w1. Between time 505a and time 505b, the heating power to the heating element is maintained at power 503a.

[0173] When the smoke detection system then detects that the airflow rate 501 has increased to a threshold of 501c at time 505c, the electrical circuit controls the power to the heating element, immediately increasing the heating power 503 from 503w1 to power 503c. When the smoke detection system detects that the airflow rate 501 has decreased to a threshold of 501d at time 505d, the electrical circuit controls the power to the heating element, immediately decreasing the heating power 503 from power 503c to 503w2. Between time 505c and time 505d, the heating power to the heating element is maintained at power 503c.

[0174] When the smoke detection system then detects that the airflow rate 501 has increased to a threshold 501e at time 505e, the electrical circuit controls the power to the heating element to immediately increase the heating power 503 from 503w2 to power 503e. When the smoke detection system detects that the airflow rate 501 has decreased to a threshold 501f at time 505f, the electrical circuit controls the power to the heating element to immediately decrease the heating power 503 from power 503e to 503w3. Between time 505e and time 505f, the heating power to the heating element is maintained at power 503e.

[0175] When the smoke detection system detects that the airflow rate 501 has decreased to below the threshold 501g, the electrical circuit controls the power to the heating element, immediately reducing the heating power 503 from power 503w3 to zero.

[0176] In the embodiment shown in Figure 5, threshold 501a is a predetermined constant, and threshold 501g is another predetermined constant for the termination of smoke extraction. Threshold 501g is smaller than threshold 501a.

[0177] The local maximum flow rate 501maxz lies between the flow rate 501max1 and the threshold 501b, and since the local maximum flow rate 501maxz is smaller than the flow rate 501max1, the local maximum flow rate 501maxz does not affect the threshold 501b. If the flow rate 501maxz is larger than the flow rate 501max1, the threshold 501b can be calculated as a percentage of the flow rate 501maxz.

[0178] Threshold 501b is 70% of 501max1. Threshold 501c is 80% of 501max1. Threshold 501d is 70% of 501max2. Threshold 501e is 80% of 501max2. Powers 503a, 503c, 503e, 503w1, 503w2, and 503w3 are predetermined powers, where the maximum of powers 503w1, 503w2, and 503w3 is less than the minimum of powers 503a, 503c, and 503e.

[0179] Of note, according to the embodiment in Figure 5, the power supplied to the heating element can increase indefinitely in response to an increase in airflow above a threshold defined by a local maximum, and decrease indefinitely in response to a decrease in airflow below a threshold defined by a local maximum. That is, while Figure 5 shows three increases in the power supplied to the heating element, different smoke extraction profiles may show four, five, or more increases in the power supplied to the heating element.

[0180] Figure 6 shows plots of airflow rate and heating power rate in an aerosol generation system according to the sixth embodiment described herein. Figure 6 shows the airflow rate 601 for the first smoke extraction 6A and the second smoke extraction 6B on the vertical axis and time 605 on the horizontal axis, while the second plot shows the heating power rate 603 for the first smoke extraction 6A and the second smoke extraction 6B on the vertical axis and time 605 on the horizontal axis. The airflow rate 601 and heating power rate 603 for smoke extraction 6A are shown as solid lines, and the airflow rate 601 and heating power rate 603 for smoke extraction 6B are shown as dotted lines. The airflow rate is sensed by a smoke extraction detection system, such as the smoke extraction detection system 111 in Figure 1. The heating power rate is the power supplied from the power source to the heating element under the control of an electrical circuit, such as the control circuit 112 in Figure 1. Figure 6 shows a single smoke extraction by a user in an electrically heated aerosol generation system, such as the one shown in Figure 1.

[0181] As can be seen in Figure 6, in this embodiment, the airflow rate for smoke extraction is illustrated as having the shape of a normal distribution or a Gaussian distribution.

[0182] For smoke extraction 6A, the airflow rate starts at zero, gradually increases to a maximum of 601maxA, and then gradually decreases back to zero. For smoke extraction 6b, the airflow rate starts at zero, gradually increases to a maximum of 601maxB, and then gradually decreases back to zero.

[0183] Threshold 601a is a predetermined constant. Threshold 601end is a predetermined constant for the end of smoke inhalation. Threshold 601bA applies to smoke inhalation A but not to smoke inhalation B, and is 50% of the local maximum 601maxA. Threshold 601bB applies to smoke inhalation B but not to smoke inhalation A, and is 50% of the local maximum 601maxB.

[0184] For smoke extraction unit 6A, when the smoke extraction detection system detects that the airflow rate 601 has increased to the threshold 601a at time 605aA, the electrical circuit controls the power to turn on the heating element and immediately increases the heating power 603 from zero to power 603a. As can be seen in Figure 6, the threshold 601end is less than the threshold 601bA, and for smoke extraction unit A, the threshold 601bA is reached before the threshold 601end. Therefore, when the smoke extraction detection system detects that the airflow rate 601 has decreased to the threshold 601bA at time 605bA, the electrical circuit controls the power to turn off the heating element and immediately decreases the heating power 603 from power 603a to zero. Between time 605a and time 605b, the heating power to the heating element is maintained at power 603a.

[0185] For smoke extraction unit 6B, when the smoke extraction detection system detects that the airflow rate 601 has increased to the threshold 601a at time 605aB, the electrical circuit controls the power to turn on the heating element and immediately increases the heating power 603 from zero to power 603a. As can be seen in Figure 6, for smoke extraction unit B, the threshold 601end is reached before the threshold 601bB. Therefore, when the smoke extraction detection system detects that the airflow rate 601 has decreased to the threshold 601end at time 605endB, the electrical circuit controls the power to turn off the heating element and immediately decreases the heating power 603 from power 603a to zero. The power supplied to the heating element does not change when the airflow rate subsequently decreases to the threshold 601bB. Between time 605a and time 605b, the heating power to the heating element is maintained at power 603a.

[0186] Figure 7 shows plots representing airflow rate over time and heating power over time in an aerosol generating system according to the eleventh embodiment described herein. The first plot in Figure 7 shows airflow rate over time, and the second plot in Figure 7 shows heating power over time. Both plots relate to a single smoke extraction by a user in an electrically heated aerosol generating system, such as that shown in Figure 1.

[0187] The first plot shows airflow rate 701 on the vertical axis and time 705 on the horizontal axis, and the second plot shows heating power 703 on the vertical axis and time 705 on the horizontal axis. The time 705 shown in both plots is the same time. That is, the plots in Figure 7 show the airflow rate and heating power for the same smoke extraction. Airflow rate 701 is shown by a solid line, and heating power 703 is shown by a dotted line. Airflow rate is sensed by a smoke extraction detection system, such as the smoke extraction detection system 111 in Figure 1. Heating power is the power supplied from the power source to the heating element under the control of an electrical circuit, such as the control circuit 112 in Figure 1. Figure 7 shows a single smoke extraction by a user in an electrically heated aerosol generation system, such as the one shown in Figure 1.

[0188] The first plot in Figure 7 shows the smoke extraction profile from zero to an airflow of 701max, and then from 701max to zero. The plot exhibits a shape similar to a normal distribution, which is positively or right-skewed.

[0189] When the smoke detection system detects that the airflow rate 701 has increased to a threshold 701a in time 705a, the electrical circuit controls the power to turn on the heating element and directly increases the heating power 703 from zero to power 703a. In this embodiment, the threshold 701a is a predetermined constant.

[0190] When the smoke detection system detects that the airflow rate 701 has decreased to a threshold 701b at time 705b, the electrical circuit controls the power to turn off the heating element and immediately reduces the heating power 703 from power 703a to zero. In this embodiment, the threshold 701b is 70% of the flow rate 701max.

[0191] Next, the smoke extraction detection system waits for a fixed time of 0.3 seconds from time 705b to time 705c. At time 705c, the smoke extraction detection system measures the flow rate as flow rate 701c and compares flow rate 701c to a restart threshold flow rate (not shown). In this embodiment, the restart threshold flow rate is 60% of flow rate 701max. If flow rate 705c is greater than the restart threshold flow rate, the electrical circuit controls the power to turn on the heating element and increase the heating power. If flow rate 705c is less than the restart threshold flow rate, the heating element remains off until smoke extraction is complete or until there is another reason to turn the heating element back on. In the embodiment of Figure 7, flow rate 705c is greater than the restart threshold flow rate, and therefore the electrical circuit controls the power to turn on the heating element and immediately increases the heating power 703 from zero to power 703c. In this embodiment, power 703c is less than power 703a.

[0192] The power supplied to the heating element remains at power 703c until the smoke detection system detects that the flow rate is less than the flow rate threshold 701d. At the flow rate threshold 701d, the electrical circuit controls the power to turn off the heating element, immediately reducing the heating power 703 from power 703c to zero.

[0193] In this embodiment, the smoke detection system measures the flow rate for a given time after the flow rate threshold 701b has been reached. This given time is equal to time 705c minus time 705b. However, similar or identical effects can be achieved in numerous alternative ways. Some of these alternatives can be illustrated with reference to Figure 7.

[0194] In one exemplary alternative, the fume extraction detection system may periodically measure the flow rate. The fume extraction detection system may compare the measured flow rate 701c to a restart threshold, where the flow rate 701c is measured over a given number of flow rate measurements after the first measurement following a decrease in flow rate below the threshold 701b. Then, as in the embodiment implemented in Figure 7, if the flow rate 705c is greater than the restart threshold flow rate, the electrical circuit controls the power to turn on the heating element and increase the heating power; however, if the flow rate 705c is less than the restart threshold flow rate, the heating element remains off until fume extraction is complete or until there is another reason to turn the heating element back on.

[0195] In a second exemplary alternative, the smoke extraction detection system may measure the flow rate continuously or intermittently. When the smoke extraction detection system detects that the airflow rate is less than threshold 701c, the aerosol generation system may compare the approximate time difference to a restart time threshold, where the approximate time difference is approximately the time between the time when the flow rate is detected to be less than threshold 701b and the time when the flow rate is detected to be less than threshold 701c, where threshold 701b is greater than threshold 701c. Therefore, if the approximate time difference is greater than the restart time threshold, the electrical circuit controls the power to turn on the heating element and increase the heating power, or if the approximate time difference is less than the restart time threshold, the heating element remains off until smoke extraction is complete or until there is another reason to turn the heating element back on.

[0196] Figure 8 shows plots of airflow rate over time and heating power over time in an aerosol generation system according to the sixteenth embodiment described herein.

[0197] Figure 8 is a plot showing airflow rate 801 on the vertical axis and time 805 on the horizontal axis, and a second plot showing heating power 803 on the vertical axis and time 805 on the horizontal axis. Airflow rate 801 is shown by a solid line, and heating power 803 is shown by a dotted line. Airflow rate is sensed by a smoke extraction detection system, such as the smoke extraction detection system 111 in Figure 1. Heating power is the power supplied from the power source to the heating element under the control of an electrical circuit, such as the control circuit 112 in Figure 1. Figure 8 shows a single smoke extraction by a user in an electrically heated aerosol generation system, such as the one shown in Figure 1. In this embodiment, the control circuit 112 shown in Figure 1 needs to include data storage means that can store the measured values ​​measured by the smoke extraction detection system 111.

[0198] As shown in Figure 8, in this embodiment, the airflow rate for smoke extraction is illustrated as having a shape similar to a normal or Gaussian distribution. The airflow rate starts at zero, gradually increases up to a maximum of 801max, and then decreases back to zero.

[0199] In this embodiment, the aerosol generation system intermittently stores the measured values ​​obtained by the smoke extraction detection system in a data storage means.

[0200] When the smoke detection system detects that the airflow rate 801 has increased to a threshold 801a in time 805a, the electrical circuit controls the power to turn on the heating element and directly increases the heating power 803 from zero to power 803a.

[0201] When the smoke extraction detection system detects that the airflow rate 801 has decreased to a threshold 801s at time 805s, the aerosol generation system begins to intermittently calculate an estimate for the remaining volume of smoke extraction based on the current detected flow rate and an estimate of the rate of change of the current flow rate. In this embodiment, the flow rate threshold 801s is 80% of the maximum detected flow rate 801max.

[0202] In this embodiment, the flow sensor intermittently stores volumetric flow values. In this context, "intermittently" means that if the values ​​were not stored periodically, the system might not function as intended, but rather periodically, every period T P It is used to mean "each". Time T P This is short compared to the average smoking period. In this embodiment, period T P This is 0.01 seconds. After reaching the threshold of 801s, the processor of the aerosol generation system calculates the average rate of change of the current flow rate A. c Calculate the average rate of change A of the current flow rate. c Q is the five flow rate values ​​stored before the current flow rate value. c-5 Current flow rate value A c Subtract from it, then divide by 5, and then for period T P It is calculated by dividing by A. Next, the processor calculates the average rate of change of this current flow A. c Let's assume that remains constant. This is the average rate of change A of the current flow rate. c If the result is negative, the remaining time T of the current smoke intake. C The current flow rate value Q c The average rate of change of the current flow rate A c This means it can be estimated to be equal to the negative of divided by . The processor then calculates the current remaining volume V of the smoke absorbed. c The estimated value is calculated by multiplying -0.5 by the square of the current flow rate and dividing by the average rate of change of the current flow rate. The processor then calculates the remaining volume V of the current smoke extraction. c Each of the calculated estimates is compared to the threshold volume. In this embodiment, the threshold volume is 3 ml.

[0203] In the first plot of Figure 8, at time 805b, the flow rate 801b is measured and stored in the data storage means. Next, an estimate of the remaining volume of smoke is calculated. This estimate of the remaining volume of smoke is shown as the shaded volume in the first plot of Figure 8. In the embodiment of Figure 8, this estimate of the remaining volume of smoke is a first estimate that is less than 3 ml. Thus, the electrical circuit controls the power to turn off the heating element and immediately reduces the heating power 803 from power 803a to zero.

[0204] The figures illustrate specific embodiments of the aspects described herein. However, it will be apparent that modifications may be made to the described embodiments within the scope of the invention. It will be apparent to those skilled in the art that, where necessary, features described in relation to one aspect or embodiment may be applied to one or more of the other aspects or embodiments.

[0205] Advantageously, all embodiments described herein provide an improved method for controlling aerosol generation in an aerosol generating system. Specifically, the claimed invention provides an improved method for controlling aerosol generation in a complex smoke extraction profile.

Claims

1. A method for controlling aerosol generation in an aerosol generation system, wherein the system Aerosol generating elements and A housing having an air intake and an air outlet, wherein a flow path is defined through the housing from the air intake to the air outlet, and the flow path provides an airflow that passes through the aerosol generating element when a user inhales smoke in the system, The method comprises a flow sensor configured to detect the airflow in the flow path indicating that the user is inhaling smoke, and the method comprises the following time-series steps: The process of increasing the power supplied to the aerosol generating element from power P0 to at least power P1 when the flow sensor detects that the flow rate of the airflow is greater than a first threshold, A step of reducing the power supplied to the aerosol generating element to power P2, wherein power P2 is less than power P1, and when the flow sensor detects that the flow rate of the airflow is less than a second threshold, the second threshold is a flow rate that is or indicates a predetermined first ratio of the first maximum flow rate detected by the flow sensor. A method comprising the step of increasing the power supplied to the aerosol generating element if the flow sensor detects that the flow rate of the airflow is greater than a third threshold before detecting that the flow rate of the airflow is less than a smoke extraction termination threshold, wherein the third threshold is greater than a second threshold and the smoke extraction termination threshold is less than a second threshold.

2. The method according to claim 1, wherein the power P0 is zero, or the power P2 is zero, or both the power P0 and the power P2 are zero.

3. The method according to claim 1 or 2, wherein the third threshold is a predetermined second ratio of the first maximum flow rate, and the predetermined second ratio is greater than the predetermined first ratio, or the third threshold is a predetermined multiple of the second threshold, and the predetermined multiple is greater than 1.

4. The method according to any one of claims 1 to 3, wherein the first threshold is a first constant, or the smoke absorption termination threshold is a smoke absorption termination constant, or the first threshold is a first constant and the smoke absorption termination threshold is a smoke absorption termination constant.

5. The method according to any one of claims 1 to 4, wherein the step of increasing the power supplied to the aerosol generating element from power P0 to at least power P1 includes increasing the power supplied to the aerosol generating element to power PX such that PX is greater than or equal to power P1, and if the flow sensor detects that the flow rate of the airflow is greater than a third threshold before detecting that the flow rate of the airflow is less than a smoke extraction termination threshold, the step of increasing the power supplied to the aerosol generating element includes increasing the power supplied to the aerosol generating element to power P3 such that P3 is less than or equal to PX.

6. The method, after the step of increasing the power supplied to the aerosol generating element if the flow sensor detects that the flow rate of the airflow is greater than a third threshold before detecting that the flow rate of the airflow is less than a smoke extraction termination threshold, The method according to any one of claims 1 to 5, further comprising the step of reducing the power supplied to the aerosol generating element to power P4 when the flow sensor detects that the flow rate of the airflow is less than the smoke extraction termination threshold.

7. The method according to claim 6, wherein the power P4 is zero.

8. The step of increasing the power supplied to the aerosol generating element from power P0 to at least power P1 includes increasing the power from power P0 to at least power P1 substantially immediately, or The step of reducing the power supplied to the aerosol generating element to the power P2 includes reducing the power supplied to the aerosol generating element to the power P2 substantially immediately, or The method according to any one of claims 1 to 7, wherein the step of increasing the power supplied to the aerosol generating element from power P0 to at least power P1 includes substantially immediately increasing the power from power P0 to at least power P1, and the step of decreasing the power supplied to the aerosol generating element to power P2 includes substantially immediately decreasing the power supplied to the aerosol generating element to power P2.

9. The step of increasing the power supplied to the aerosol generating element from power P0 to at least power P1 includes increasing the power in stages from power P0 to at least power P1, or The step of reducing the power supplied to the aerosol generating element to power P2 includes gradually reducing the power supplied to the aerosol generating element to power P2, or The method according to any one of claims 1 to 6, wherein the step of increasing the power supplied to the aerosol generating element from power P0 to at least power P1 includes gradually increasing the power from power P0 to at least power P1, and the step of decreasing the power supplied to the aerosol generating element to power P2 includes gradually decreasing the power supplied to the aerosol generating element to power P2.

10. The above method is performed after the step of increasing the power supplied to the aerosol generating element from power P0 to at least power P1, but before the step of decreasing the power supplied to the aerosol generating element to power P2, The method according to any one of claims 1 to 9, further comprising the step of increasing the power supplied to the aerosol generating element from at least the power P1 to the power P5.

11. The method according to any one of claims 1 to 10, wherein supplying power to the aerosol generating element includes supplying a current pulse to the aerosol generating element.

12. an aerosol generating system, wherein the system Aerosol generating elements and A flow path configured to allow the airflow to pass through the aerosol generating element, A flow sensor configured to detect the aforementioned airflow, wherein the airflow indicates that the user is inhaling smoke. A power supply for supplying power to the aerosol generating element, An aerosol generating system comprising: an electrical circuit for controlling the supply of power from the power source to the aerosol generating element, wherein the electrical circuit is arranged to carry out the method according to any one of claims 1 to 11.

13. An electrical circuit for an aerosol generating system, wherein the electrical circuit is arranged to carry out the method according to any one of claims 1 to 11.

14. A computer program, which, when executed on a programmable electrical circuit for an aerosol generating system, causes the programmable electrical circuit to perform any of the methods described in claims 1 to 11.

15. A computer-readable storage medium for storing the computer program described in claim 14.

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