Aerosol generating system having means for determining whether a liquid aerosol-forming substrate is being supplied to a susceptor - Patent application

Abstract

The present disclosure relates to an aerosol generating system. The aerosol generating system includes a liquid reservoir (44) for storing a liquid aerosol-forming substrate (42). The aerosol generating system includes susceptors (16, 18) for receiving a supply of the liquid aerosol-forming substrate (42) from the liquid reservoir (44) and heating the liquid aerosol-forming substrate (42) to form an aerosol. The aerosol generating system includes an inductor coil (90) configured to generate an alternating magnetic field for heating the susceptors (16, 18). The aerosol generating system includes a power source (72) configured to supply electricity to the inductor coil (90). The aerosol generating system includes a control circuit (70) configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on the electricity supplied to the inductor coil. The control circuit is configured to determine whether the susceptor is supplied with a liquid aerosol-forming substrate based on a comparison of the parameter indicative of the rate of change of temperature of the susceptor to a dry susceptor threshold. The present invention also relates to an aerosol generating device (60) for use in an aerosol generating system, and to a method of controlling an aerosol generating system.

Description

[Technical Field]

[0001] The present disclosure relates to an aerosol generation system. In particular, the present disclosure relates to an inductively heated aerosol generation system for generating an aerosol from a liquid aerosol-forming substrate. The present disclosure also relates to an aerosol generating device for use in the aerosol generation system. The present disclosure further relates to a method for controlling the aerosol generation system. [Background technology]

[0002] Aerosol generation systems that use induction heating to heat an aerosol-forming substrate to generate an aerosol for user inhalation are generally known in the prior art. These systems typically include an aerosol-generating device including an induction heating assembly and a cartridge including an aerosol-forming substrate capable of releasing a volatile compound upon heating, which cools to form an inhalable aerosol. The cartridge is configured to be coupled to the aerosol-generating device. The induction heating assembly includes at least one inductor coil configured to generate an alternating magnetic field within a cavity. A susceptor forming either the cartridge or the device is positioned within the alternating magnetic field in close proximity to the aerosol-forming substrate. When the susceptor is penetrated by the alternating magnetic field, it heats by at least one of Joule heating from an eddy current induced in the susceptor and hysteresis losses. The heated susceptor heats the aerosol-forming substrate, releasing the volatile compound from the aerosol-forming substrate, which cools to form an inhalable aerosol.

[0003] One advantage of induction heating systems is that the electrical components of the system can be separated from the aerosol-forming substrate and the generated aerosol. Another advantage is that the construction of the cartridge can be simplified because there is no need to provide electrical connections to the aerosol-generating device.

[0004] Some induction-heated aerosol generating systems are configured for use with a liquid aerosol-forming substrate stored in a liquid reservoir. During use, as the liquid aerosol-forming substrate is heated to generate an aerosol, the amount of liquid aerosol-forming substrate in the liquid reservoir decreases. When the liquid reservoir is empty or nearly empty, the amount of liquid aerosol-forming substrate supplied to the susceptor may be insufficient to generate a satisfactory aerosol. For example, the aerosol's characteristics, such as volume, composition, or flavor, may be unsatisfactory. This can result in a poor user experience. A temporary interruption in the supply of liquid aerosol-forming substrate to the susceptor may also result in an unsatisfactory aerosol.

[0005] It would be desirable to provide an inductively heated aerosol generating system that can determine whether a susceptor is supplied with a liquid aerosol-forming substrate. It would be desirable for such an aerosol generating system to not result in a substantial increase in the number of electrical components compared to some known prior art systems. Summary of the Invention

[0006] According to one embodiment of the present disclosure, there is provided an aerosol generation system. The aerosol generation system includes a liquid reservoir for storing a liquid aerosol-forming substrate. The aerosol generation system includes a susceptor for receiving a supply of the liquid aerosol-forming substrate from the liquid reservoir and heating the liquid aerosol-forming substrate to form an aerosol. The aerosol generation system includes an inductor coil configured to generate an alternating magnetic field to heat the susceptor. The aerosol generation system includes a power source configured to supply electricity to the inductor coil. The aerosol generation system includes a control circuit configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on the electricity supplied to the inductor coil. The control circuit is configured to determine whether the susceptor is supplied with a liquid aerosol-forming substrate based on a comparison between a dry susceptor threshold and the parameter indicative of the rate of change of temperature of the susceptor.

[0007] During heating and cooling of the susceptor, the rate of change of temperature of the susceptor varies depending on whether a liquid aerosol-forming substrate is provided to the susceptor. This is because when a liquid aerosol-forming substrate is provided to the susceptor, the susceptor dissipates most of the heat by transferring the heat to the liquid aerosol-forming substrate. On the other hand, when a liquid aerosol-forming substrate is not provided to the susceptor, the susceptor cannot dissipate heat as quickly.

[0008] During susceptor heating, for the same power supply voltage, the rate of increase in the temperature of the susceptor is lower when a liquid aerosol-forming substrate is provided to the susceptor than when no liquid aerosol-forming substrate is provided to the susceptor. Meanwhile, during susceptor cooling, the rate of decrease in the temperature of the susceptor is higher when a liquid aerosol-forming substrate is provided to the susceptor than when no liquid aerosol-forming substrate is provided to the susceptor. Advantageously, determining a parameter indicative of the rate of change of the temperature of the susceptor enables the control circuit to determine whether a liquid aerosol-forming substrate is provided to the susceptor. This means that the control circuit can perform an action in response to determining whether a liquid aerosol-forming substrate is provided to the susceptor.

[0009] The control circuit determines whether the susceptor is being supplied with a liquid aerosol-forming substrate based on a comparison of the dry susceptor threshold with a parameter indicative of the rate of change of temperature of the susceptor. Advantageously, this allows the dry susceptor threshold to be selected to suit a particular susceptor configuration or composition of the liquid aerosol-forming substrate.

[0010] A parameter indicative of the susceptor's rate of temperature change is determined based on the electricity supplied to the inductor coil. Advantageously, this allows for remote detection of the susceptor's rate of temperature change; i.e., there is no need for a physical connection between the control circuit and the susceptor. Another advantage is that there is no need to provide additional electrical components, such as temperature sensors, to monitor the susceptor's rate of temperature change.

[0011] As used herein, the term "based on electricity" may refer to "based on at least one of the current and voltage of electricity." Similarly, the term "based on the initial supply of electricity" may refer to "based on at least one of the current and voltage of the initial supply of electricity."

[0012] As used herein, the terms "susceptor" or "susceptor element" refer to an element that can be heated by penetration by an alternating magnetic field. The susceptor is typically heatable by at least one of Joule heating through the induction of eddy currents in the susceptor and hysteresis losses. Possible materials for the susceptor include graphite, molybdenum, silicon carbide, stainless steel, niobium, and aluminum. Advantageously, the susceptor can have a relative permeability of 1 to 40,000. Materials with lower permeabilities may be used when it is desired to rely mostly on eddy currents for heating, and materials with higher permeabilities may be used when hysteresis effects are desired. Preferably, the material has a relative permeability of 500 to 40,000.

[0013] The parameter indicative of the rate of change of temperature of the susceptor may be based on an electrical characteristic of the inductor coil.The parameter indicative of the rate of change of temperature of the susceptor may be based on the quotient of the voltage and current of the electricity supplied to the inductor coil.

[0014] The parameter indicative of the susceptor's temperature change rate may be the rate of change of the inductor coil's apparent ohmic resistance. Alternatively, the parameter indicative of the susceptor's temperature change rate may be the rate of change of the inductor coil's apparent conductance. Advantageously, when the inductor coil and the susceptor are electromagnetically coupled, the rate of change of the inductor coil's apparent resistance depends on the susceptor's temperature change rate. Furthermore, there may be a slight delay between the change in the susceptor's temperature and the resulting change in the inductor coil's apparent resistance. This means that the rate of change of the apparent ohmic resistance may accurately indicate the susceptor's temperature change rate, with a slight time lag. Because conductance is the mathematical inverse of resistance, the inductor coil's apparent conductance also depends on the susceptor's temperature change rate.

[0015] As used herein, the term "apparent ohmic resistance" refers to the ohmic resistance "seemed" by an inductor coil when the susceptor is electromagnetically coupled to the inductor coil. When the inductor coil and the susceptor are electromagnetically coupled, the apparent ohmic resistance of the inductor coil includes both the ohmic resistance of the inductor coil and the ohmic resistance of the susceptor. In other words, when the inductor coil and the susceptor are electromagnetically coupled, the apparent ohmic resistance of the inductor coil is the equivalent ohmic resistance of the inductor coil and the susceptor. The ohmic resistance of the inductor coil remains relatively constant during induction heating of the susceptor, while the ohmic resistance of the susceptor changes with the temperature of the susceptor. Therefore, the apparent ohmic resistance of the inductor coil changes with the temperature of the susceptor. Because conductance is the mathematical inverse of resistance, the term "apparent conductance" can be understood similarly.

[0016] The parameter indicative of the rate of change of temperature of the susceptor may be based on a first measurement of the electricity supplied to the inductor coil and a second measurement of the electricity supplied to the inductor coil.

[0017] The control circuit may be configured to determine a first parameter indicative of the temperature of the susceptor based on the first measurement. For example, the first parameter indicative of the temperature of the susceptor may be a first apparent ohmic resistance of the inductor coil. The control circuit may be configured to determine a second parameter indicative of the temperature of the susceptor based on the second measurement. For example, the second parameter indicative of the temperature of the susceptor may be a second apparent ohmic resistance of the inductor coil.

[0018] The control circuit may be configured to determine a first parameter indicative of a rate of change of temperature of the susceptor based on the first measurement. For example, the first parameter indicative of a rate of change of temperature of the susceptor may be a first rate of change of the apparent ohmic resistance of the inductor coil. The control circuit may be configured to determine a second parameter indicative of a rate of change of temperature of the susceptor based on the second measurement. For example, the second parameter indicative of a rate of change of temperature of the susceptor may be a second rate of change of the apparent ohmic resistance of the inductor coil. The parameter indicative of a rate of change of temperature of the susceptor may be an average of the first parameter indicative of a rate of change of temperature of the susceptor and the second parameter indicative of a rate of change of temperature of the susceptor.

[0019] The first and second measurements may be separated by a time interval. The time interval may be less than 500 milliseconds, less than 400 milliseconds, less than 300 milliseconds, less than 250 milliseconds, less than 200 milliseconds, less than 150 milliseconds, less than 100 milliseconds, or less than 50 milliseconds. The time interval may be between 50 milliseconds and 100 milliseconds. Preferably, the time interval is between 50 milliseconds and 200 milliseconds. Advantageously, a short time interval may allow a parameter indicative of the rate of change of temperature of the susceptor to be determined multiple times during use of the aerosol generating system.

[0020] The parameter indicating the rate of change of the temperature of the susceptor may be a parameter indicating the rate of increase of the temperature of the susceptor.

[0021] The control circuit may be configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on electricity supplied to the inductor coil during a heating period of the susceptor. During the heating period, the temperature of the susceptor increases from a first temperature to a second temperature. The temperature of the susceptor may not decrease during the heating period. The first temperature may be 100°C or less. The second temperature may be 100°C or greater. The first temperature may be 50°C to 100°C, 50°C to 90°C, 50°C to 80°C, 50°C to 70°C, or 50°C to 60°C. The second temperature may be 120°C to 200°C, 130°C to 200°C, 140°C to 200°C, or 150°C to 200°C.

[0022] The parameter indicating the rate of change in temperature of the susceptor may be a parameter indicating the rate of decrease in temperature of the susceptor.

[0023] The control circuit may be configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on electricity supplied to the inductor coil during a cooling period of the susceptor. During the cooling period, the temperature of the susceptor decreases from a first temperature to a second temperature. The temperature of the susceptor may not increase during the cooling period. The first temperature may be 100°C or higher. The second temperature may be 100°C or lower. The first temperature may be 120°C to 200°C, 130°C to 200°C, 140°C to 200°C, or 150°C to 200°C. The second temperature may be 50°C to 100°C, 50°C to 90°C, 50°C to 80°C, 50°C to 70°C, or 50°C to 60°C.

[0024] The control circuit may be configured to determine that the susceptor is being supplied with a liquid aerosol-forming substrate when the parameter indicative of the rate of change of temperature of the susceptor is less than a dry susceptor threshold, or in other words, to determine that the susceptor is not being supplied with a liquid aerosol-forming substrate when the parameter indicative of the rate of change of temperature of the susceptor is greater than a dry susceptor threshold.

[0025] The dry susceptor threshold during cooling may be different from the dry susceptor threshold during heating.

[0026] The control circuit may be configured to determine whether the liquid reservoir is depleted based on whether the susceptor is supplied with liquid aerosol-forming substrate. Advantageously, this may allow the control circuit to prevent further use of the aerosol-generating system until the liquid reservoir is replenished.

[0027] The control circuitry may be configured to determine that the liquid reservoir is depleted when the susceptor has not been supplied with liquid aerosol-forming substrate for a time period equal to or greater than a time threshold, or in other words, when a parameter indicative of a rate of change of temperature of the susceptor is greater than a dry susceptor threshold for a time period equal to or greater than the time threshold.

[0028] The control circuit may be configured to determine that the liquid reservoir is depleted when the control circuit determines that the susceptor has not been supplied with the liquid aerosol-forming substrate a predetermined number of times in a row. Each determination that the susceptor has not been supplied with the liquid aerosol-forming substrate may be based on a separate measurement of the electricity supplied to the inductor coil. The predetermined number may be 2, 3, 4, 5, 6, 7, 8, 9, or 10 times.

[0029] The control circuit may be configured to detect the abnormal condition based on whether the susceptor is supplied with a liquid aerosol-forming substrate. The control circuit may be configured to detect the abnormal condition when the susceptor is not supplied with a liquid aerosol-forming substrate for a time period shorter than a time threshold. In other words, the control circuit may be configured to detect the abnormal condition of the aerosol-generating system when a parameter indicative of a rate of change of temperature of the susceptor is greater than a dry susceptor threshold for a time period shorter than a time threshold.

[0030] The control circuit may be configured to detect an abnormal condition when the control circuit determines that the susceptor has not been supplied with the liquid aerosol-forming substrate a predetermined number of times or less. Each determination that the susceptor has not been supplied with the liquid aerosol-forming substrate may be based on a separate measurement of the electricity supplied to the inductor coil. The predetermined number may be two, three, four, five, six, seven, eight, nine, or ten times.

[0031] Under abnormal conditions, the aerosol-generating system may not function as designed. For example, the supply of liquid aerosol-forming substrate to the susceptor may be temporarily interrupted. This may be the result of how the aerosol-generating system is oriented.

[0032] The control circuit may include an orientation sensor for detecting the orientation of the liquid reservoir, and may be configured to use the orientation sensor to determine whether the supply of liquid aerosol-forming substrate to the susceptor is temporarily disrupted.

[0033] The time threshold may be at least 10 milliseconds. The time threshold may be at least 50 milliseconds. The time threshold may be 10 milliseconds to 2000 milliseconds, 10 milliseconds to 1500 milliseconds, 10 milliseconds to 1000 milliseconds, or 50 milliseconds to 1000 milliseconds. The time threshold may be 10 milliseconds, 50 milliseconds, 100 milliseconds, 150 milliseconds, 200 milliseconds, 250 milliseconds, 300 milliseconds, 350 milliseconds, 400 milliseconds, 450 milliseconds, 500 milliseconds, 550 milliseconds, 600 milliseconds, 650 milliseconds, 700 milliseconds, 750 milliseconds, 800 milliseconds, 950 milliseconds, 1000 milliseconds, 1500 milliseconds, or 2000 milliseconds.

[0034] The control circuit may be configured to determine a fault condition when the abnormal condition is detected at least two times. The control circuit may be configured to determine a fault condition when the abnormal condition is detected at least three times. The control circuit may be configured to determine a fault condition when the abnormal condition is detected at least four times. The control circuit may be configured to determine a fault condition when the abnormal condition is detected at least five times. In a fault condition, the control circuit may determine that the abnormal condition is caused by a malfunction of the aerosol generation system. For example, residue may build up in the aerosol generation system that temporarily prevents the delivery of liquid aerosol-forming substrate to the susceptor. In a fault condition, it may be necessary to replace a portion of the system to restore the system to normal operation.

[0035] The control circuit may be configured to provide an indication to a user when it is determined that the susceptor is not being supplied with liquid aerosol-forming substrate. The control circuit may be configured to provide an indication to a user when it is determined that the liquid reservoir is depleted. The control circuit may be configured to provide an indication to a user when an abnormal condition is detected. The control circuit may be configured to provide an indication to a user when a fault condition is detected.

[0036] The control circuitry may be configured to provide an audible indication to the user. For example, the aerosol generation system may include a speaker. The control circuitry may be configured to operate the speaker to provide the audible indication to the user.

[0037] The control circuitry may be configured to provide a visual indication to the user. For example, the aerosol generation system may include one or more indicator lights. The control circuitry may be configured to operate the one or more indicator lights to provide a visual indication to the user.

[0038] The control circuitry may be configured to provide a tactile indication to the user. For example, the aerosol generation system may include a vibration motor. The control circuitry may be configured to operate the vibration motor to provide a tactile indication to the user.

[0039] The control circuit may be configured to operate the aerosol generation system in a first mode and a second mode, the first mode being different from the second mode.

[0040] The first mode may be a high power mode. In the high power mode, the control circuit may be configured to supply electricity to the inductor coil. The second mode may be a low power mode. In the low power mode, the control circuit may be configured to prevent the supply of electricity to the inductor coil. Alternatively, in the low power mode, the control circuit may be configured to supply electricity of a lower voltage to the inductor coil compared to the high power mode.

[0041] The control circuit may be configured to operate the aerosol-generation system in a first mode when the susceptor is supplied with a liquid aerosol-forming substrate, and may be configured to operate the aerosol-generation system in a second mode when the susceptor is not supplied with a liquid aerosol-forming substrate.

[0042] The control circuitry may be configured to operate the aerosol generation system in a first mode when the liquid reservoir is not depleted, and may be configured to operate the aerosol generation system in a second mode when the liquid reservoir is depleted.

[0043] The control circuit may be configured to operate the aerosol generation system in the first mode when no abnormal condition is detected, and the control circuit may be configured to operate the aerosol generation system in the second mode when an abnormal condition is detected.

[0044] The control circuit may be configured to operate the aerosol generation system in a first mode when no fault condition is detected, and to operate the aerosol generation system in a second mode when a fault condition is detected.

[0045] The aerosol generation system may include an information storage component. The information storage component may be configured to store the dry susceptor threshold. The control circuit may include means for retrieving the dry susceptor threshold from the information storage component. The information storage component may be an electronic memory. The electronic memory may be an RFID (Radio Frequency Identification) tag. The information storage component may be a one-dimensional barcode. The information storage component may be a two-dimensional barcode.

[0046] The dry susceptor threshold may be predetermined. The dry susceptor threshold may be stored on an information storage component. The dry susceptor threshold may be stored in the information storage component during manufacture of the aerosol-generating system. The dry susceptor threshold may also be determined experimentally. For example, the dry susceptor threshold may be determined by supplying electricity to an inductor coil when no liquid aerosol-forming substrate is supplied to the susceptor and determining a parameter indicative of the rate of change of temperature of the susceptor, which parameter may then be used as the dry susceptor threshold.

[0047] The control circuitry may be configured to determine a dry susceptor threshold, which may advantageously allow the aerosol-generating system to be used with liquid aerosol-forming substrate compositions and susceptor configurations that do not have a pre-programmed dry susceptor threshold.

[0048] The control circuit may be configured to determine the dry susceptor threshold based on an initial supply of electricity to the inductor coil. The initial supply of electricity may be supplied to the inductor coil when the aerosol generation system is first turned on. The initial supply of electricity may be supplied to the inductor coil when a first puff is taken with the aerosol generation system.

[0049] The control circuit may be configured to determine a parameter indicative of an initial rate of change of temperature of the susceptor based on an initial supply of electricity to the inductor coil.

[0050] The susceptor may not be supplied with a liquid aerosol-forming substrate during the initial supply of electricity to the inductor coil. For example, the aerosol generating system may include a seal configured to prevent the liquid aerosol-forming substrate from being supplied to the susceptor, and the seal may be broken after determining a parameter indicative of an initial rate of change of temperature of the susceptor. The dry susceptor threshold may be the parameter indicative of the initial rate of change of temperature of the susceptor. In other words, the control circuit stores the value of the parameter indicative of the initial rate of change of temperature of the susceptor and uses the value as the dry susceptor threshold.

[0051] The aerosol generation system may include a wicking element. The wicking element may be in fluid communication with the susceptor. The wicking element may be in fluid communication with a liquid reservoir. The wicking element may be arranged to transport the liquid aerosol-forming substrate from the liquid reservoir to the susceptor. In particular, the wicking element may be arranged to transport the liquid aerosol-forming substrate from the liquid reservoir across a major surface of the susceptor. The susceptor may be fixed to the wicking element. The susceptor may be integral with the wicking element.

[0052] The wicking element may include a capillary material. A capillary material is a material capable of transferring liquid from one end of the material to another by capillary action. The capillary material may have a fibrous or spongy structure. Preferably, the capillary material includes a bundle of capillaries. For example, the capillary material may include a plurality of fibers or threads or other fine tubes. The fibers or threads may be generally aligned to transport the liquid aerosol-forming substrate across the major surface of the susceptor. The capillary material may include a spongy or foam-like material. The structure of the capillary material may form a plurality of small holes or tubes through which the liquid aerosol-forming substrate can be transported by capillary action. If the susceptor includes gaps or openings, the capillary material may extend into the gaps or openings in the susceptor element. The susceptor may draw the liquid aerosol-forming substrate into the gaps or openings by capillary action.

[0053] The susceptor may include one or more susceptor elements. The susceptor may be disposed substantially outside the liquid reservoir. The or each susceptor element of the susceptor may be disposed substantially outside the liquid reservoir. In particular, it is preferred that at least a portion of a major surface of the or each susceptor element is not in direct contact with the liquid reservoir. It is preferred that at least a portion of two opposing major surfaces of the susceptor be in direct contact with air in the airflow passage of the system.

[0054] The susceptor may include a plurality of susceptor elements. The susceptor may include a first susceptor element and a second susceptor element, the second susceptor element being spaced apart from the first susceptor element. A wicking element may be disposed in the space between the first susceptor element and the second susceptor element. The wicking element may include a first wicking layer and a second wicking layer. A spacer element may be positioned between the first wicking layer and the second wicking layer. The spacer element may be fluid-permeable and configured to allow the liquid aerosol-forming substrate to move through the spacer element between the first wicking layer and the second wicking layer.

[0055] The first susceptor element may be in physical contact with a first side of the first wicking element. The second side of the first wicking element may be in contact with a first side of the spacer element. The second side of the spacer element may be in contact with a first side of the second wicking element. The second side of the second wicking element may be in contact with a second susceptor element.

[0056] The first susceptor element, the second susceptor element, and the wicking element may be substantially planar, and the first susceptor element may be disposed on a first side of the planar wicking element, and the second susceptor element may be disposed on a second side of the planar wicking element opposite the first side.

[0057] The susceptor may be in the form of a mesh. The or each susceptor element may comprise a mesh. The susceptor, or susceptor element, may comprise an array of filaments forming a mesh. As used herein, the term "mesh" encompasses grids and arrays of filaments having spaces therebetween. The term mesh also includes woven and nonwoven fabrics.

[0058] The filaments may define gaps between them, and the gaps may have a width of 10 micrometers to 100 micrometers. Preferably, the filaments create capillary action within the gaps such that, in use, source liquid is drawn into the gaps, increasing the contact area between the susceptor element and the liquid.

[0059] The filaments may form a mesh with a size of 160 to 600 mesh US (+ / - 10%) (i.e., 160 to 600 filaments per inch (+ / - 10%)). The gap width may be 35 micrometers to 140 micrometers, or 25 micrometers to 75 micrometers. For example, the gap width may be 40 micrometers or 63 micrometers. The percentage open area of ​​the mesh, which is the ratio of the gap area to the total area of ​​the mesh, is preferably 25 to 56%. The mesh may be formed using different types of weave or lattice structures. Alternatively, the filaments may be composed of a circular array of filaments arranged parallel to one another.

[0060] The filaments may be formed by etching a sheet material such as foil. This may be particularly advantageous when the heater assembly comprises an array of parallel filaments. Where the heating element comprises a mesh or fabric of filaments, the filaments may be individually formed or woven together.

[0061] The mesh is preferably sintered. Advantageously, sintering the mesh creates electrical bonds between filaments extending in different directions. In particular, when the mesh comprises one or more woven and nonwoven fabrics, it is advantageous to sinter the mesh so that electrical bonds are created between overlapping filaments.

[0062] A mesh may also be characterized by its ability to retain liquid, as is well known in the art.

[0063] The filaments of the mesh may have a diameter of 8 micrometers to 100 micrometers, 30 micrometers to 100 micrometers, 8 micrometers to 50 micrometers, or 8 micrometers to 39 micrometers. The filaments of the mesh may have a diameter of 50 micrometers.

[0064] The filaments of the mesh may have any suitable cross-section, for example, the filaments may be round or flat in cross-section.

[0065] Advantageously, the mesh susceptor element may have a relative permeability of 1 to 40,000. A material with a lower permeability may be used when it is desired to rely mostly on eddy currents for heating, and a material with a higher permeability may be used when a hysteresis effect is desired. Preferably, the material has a relative permeability of 500 to 40,000. This may provide efficient heating of the susceptor element.

[0066] The inductor coil may be a helical coil. The helical coil may be formed from wire. The wire may have a circular cross section. The wire may be made from copper. The helical coil may have a varying pitch. The inductor coil may have a circular cross section when viewed parallel to the longitudinal axis of the aerosol generating device.

[0067] The inductor coil may include a first inductor coil and a second inductor coil. The first inductor coil may be configured to generate an alternating magnetic field for heating the susceptor. The control circuit may be configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on electricity supplied to the second inductor coil.

[0068] The control circuit may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, or an application-specific integrated chip (ASIC) or other electronic circuit capable of providing control. The control circuit may be configured to continuously supply electricity to the inductor coil after system startup, or may be configured to supply electricity intermittently, such as after each puff. Electricity may be supplied to the inductor coil in the form of current pulses, for example, by pulse-width modulation (PWM). The control circuit may include a DC / AC inverter, which may include a class D or class E power amplifier. The control circuit may include additional electronic components. For example, in some embodiments, the control circuit may include a sensor element, a switch element, or a display element.

[0069] The power source may be a DC power source. The power source may be a battery. The battery may be a lithium-based battery, such as a lithium cobalt battery, a lithium iron phosphate battery, a lithium titanate battery, or a lithium polymer battery. The battery may be a nickel-metal hydride battery or a nickel-cadmium battery. The power source may be another form of charge storage device, such as a capacitor. The power source may be rechargeable and configured for numerous charge-discharge cycles. The power source may have a capacity that allows for the storage of sufficient energy for one or more user experiences with the aerosol generating system; for example, the power source may have a capacity sufficient to allow continuous production of aerosol for approximately six minutes, corresponding to the typical time it takes to smoke one conventional cigarette, or a multiple of six minutes. In another embodiment, the power source may have a capacity sufficient to allow for a predetermined number of puffs or for discontinuous activation of the atomizing assembly.

[0070] The aerosol generation system may include an aerosol generator, the aerosol generator may include a power source, the aerosol generator may include an inductor coil, and the aerosol generator may include control circuitry.

[0071] The aerosol generating device may include a housing. The housing may be elongated. The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composites containing one or more of these materials, or thermoplastics suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. Preferably, the material is light and not brittle.

[0072] The aerosol generator housing may define a cavity for receiving the cartridge. The aerosol generator may include one or more air inlets. The one or more air inlets may allow ambient air to be drawn into the cavity.

[0073] The aerosol generating device may have a connecting end configured to connect the aerosol generating device to the cartridge. The connecting end may include a cavity for receiving the cartridge.

[0074] The aerosol generating device may have a distal end opposite the connecting end, which may include an electrical connector configured to connect the aerosol generating device to an electrical connector of an external power source for charging the power source of the aerosol generating device.

[0075] The aerosol generating device may include a magnetic flux concentrator element. The magnetic flux concentrator element may have a radius larger than that of the inductor coil and at least partially surround the inductor coil. The magnetic flux concentrator element may be configured to reduce stray power losses from the generated magnetic field. The magnetic flux concentrator element may be configured to concentrate the alternating magnetic field generated by the inductor coil within the cavity.

[0076] The aerosol generation system may include a cartridge. The cartridge may include a liquid reservoir. The cartridge may include a susceptor. The cartridge may include an information storage component.

[0077] The cartridge may include an outer housing. The outer housing may be formed from a durable material. The outer housing may be formed from a liquid-impermeable material. The outer housing may be formed from a moldable plastic material such as polypropylene (PP) or polyethylene terephthalate (PET). The outer housing may be formed from the same material as the susceptor holder or may be formed from a different material.

[0078] The aerosol-generating system may comprise a liquid aerosol-forming substrate. The aerosol-forming substrate may be liquid at room temperature. The aerosol-forming substrate may comprise both liquid and solid components. The liquid aerosol-forming substrate may comprise nicotine. The nicotine-containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may comprise a plant-derived material. The liquid aerosol-forming substrate may comprise tobacco. The liquid aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds that are released from the aerosol-forming substrate upon heating. The liquid aerosol-forming substrate may comprise a homogenised tobacco material. The liquid aerosol-forming substrate may comprise a non-tobacco-containing material. The liquid aerosol-forming substrate may comprise a homogenised plant-derived material.

[0079] The liquid aerosol-forming substrate may include one or more aerosol formers. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense, stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperature of the system. Examples of suitable aerosol formers include glycerin and propylene glycol. Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (e.g., triethylene glycol, 1,3-butanediol, glycerin), esters of polyhydric alcohols (e.g., glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (e.g., dimethyl dodecanedioate, dimethyl tetradecanedioate). The liquid aerosol-forming substrate may include water, solvents, ethanol, plant extracts, and natural or artificial flavors.

[0080] The liquid aerosol-forming substrate may comprise nicotine and at least one aerosol former. The aerosol former may be glycerin or propylene glycol. The aerosol former may comprise both glycerin and propylene glycol. The liquid aerosol-forming substrate may have a nicotine concentration of about 0.5% to about 10%, for example, about 2%.

[0081] The cartridge may include two parts, a first part and a second part. The second part may be movable relative to the first part. The first and second parts of the cartridge may be movable relative to each other between a storage configuration and a use configuration. In the storage configuration, the susceptor may be separated from the aerosol-forming substrate. In the use configuration, the susceptor may be in fluid communication with the aerosol-forming substrate.

[0082] The liquid reservoir may comprise two portions, a first portion and a second portion. A seal may be provided between the first portion and the second portion. The seal may be arranged to prevent fluid communication between the first portion of the liquid reservoir and the second portion of the liquid reservoir. In other words, the seal may fluidly isolate the first portion of the liquid reservoir from the second portion of the liquid reservoir. In the storage configuration, the liquid aerosol-forming substrate may be held in the first portion of the liquid reservoir. In the storage configuration, the seal may prevent the aerosol-forming substrate from flowing from the first portion of the liquid reservoir to the second portion of the liquid reservoir.

[0083] According to an embodiment of the present disclosure, there is provided an aerosol generating device. The aerosol generating device may be an aerosol generating device as disclosed herein. In particular, the aerosol generating device may include a power source, an inductor coil, and a control circuit as disclosed herein.

[0084] According to an embodiment of the present disclosure, there is provided a method for controlling an aerosol-generating system including a liquid reservoir for storing a liquid aerosol-forming substrate, a susceptor for receiving a supply of the liquid aerosol-forming substrate, and an inductor coil configured to generate an alternating magnetic field for heating the susceptor, the method including: supplying electricity to the inductor coil; determining a parameter indicative of a rate of change of temperature of the susceptor based on the electricity supplied to the inductor coil; and determining whether the susceptor is supplied with a liquid aerosol-forming substrate based on a comparison of the parameter indicative of the rate of change of temperature of the susceptor to a dry susceptor threshold.

[0085] The method may further include operating the aerosol-generating system in a first mode when the susceptor is supplied with a liquid aerosol-forming substrate, and operating the aerosol-generating system in a second mode when the susceptor is not supplied with a liquid aerosol-forming substrate.

[0086] It should be understood that features described herein in relation to one embodiment of the present disclosure may also be applied to other embodiments of the present disclosure. In particular, features described in relation to an aerosol generation system may also be applied to an aerosol generation device. Furthermore, features described in relation to an aerosol generation system may also be applied to a method of controlling such an aerosol generation system.

[0087] The present invention is defined in the claims. However, below is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein. [Example]

[0088] Example 1. An aerosol generating system comprising: a liquid reservoir for storing the liquid aerosol-forming substrate; a susceptor for receiving a supply of liquid aerosol-forming substrate from a liquid reservoir and for heating the liquid aerosol-forming substrate to form an aerosol; an inductor coil configured to generate an alternating magnetic field for heating the susceptor; a power source configured to supply electricity to the inductor coil; a control circuit configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on the electricity supplied to the inductor coil; The aerosol generating system, wherein the control circuit is configured to determine whether the susceptor is supplied with a liquid aerosol-forming substrate based on a comparison between a dry susceptor threshold and a parameter indicative of a rate of change of temperature of the susceptor.

[0089] Example 2. The aerosol generation system of example 1, wherein the parameter indicative of the rate of change of temperature of the susceptor is based on the electrical properties of the inductor coil.

[0090] Example 3. The aerosol generation system of Example 1 or Example 2, wherein the parameter indicative of the rate of change of temperature of the susceptor is based on the quotient of the electrical voltage and current supplied to the inductor coil.

[0091] Example 4. An aerosol generating system according to any one of Examples 1 to 3, wherein the parameter indicative of the rate of change of temperature of the susceptor is the rate of change of the apparent ohmic resistance of the inductor coil.

[0092] Example 5. The aerosol generating system according to any one of Examples 1 to 3, wherein the parameter indicating the rate of change of the temperature of the susceptor is the rate of change of the apparent conductance of the inductor coil.

[0093] Example 6. An aerosol generating system according to any of Examples 1-5, wherein the parameter indicative of the rate of change of temperature of the susceptor is based on a first measurement of electricity supplied to the inductor coil and a second measurement of electricity supplied to the inductor coil.

[0094] Example 7. The aerosol generation system of Example 6, wherein the control circuit is configured to determine a first parameter indicative of the temperature of the susceptor based on the first measurement.

[0095] Example 8. The aerosol generation system of example 6 or example 7, wherein the control circuit is configured to determine a second parameter indicative of the temperature of the susceptor based on the second measurement.

[0096] Example 9. The aerosol generation system of Example 6, wherein the control circuit is configured to determine a first parameter indicative of a rate of change of temperature of the susceptor based on the first measurement.

[0097] Example 10. The aerosol generation system of example 6 or example 9, wherein the control circuit is configured to determine a second parameter indicative of a rate of change of temperature of the susceptor based on the second measurement.

[0098] Example 11. An aerosol generating system as described in Example 9 or Example 10, wherein the parameter indicative of the susceptor temperature change rate is the average of a first parameter indicative of the susceptor temperature change rate and a second parameter indicative of the susceptor temperature change rate.

[0099] Example 12. The aerosol generating system of any one of Examples 6 to 11, wherein the first measurement and the second measurement are separated by a time interval.

[0100] Example 13. The aerosol generating system of Example 12, wherein the time interval is less than 500 milliseconds, less than 400 milliseconds, less than 300 milliseconds, less than 250 milliseconds, less than 200 milliseconds, less than 150 milliseconds, less than 100 milliseconds, or less than 50 milliseconds.

[0101] Example 14. An aerosol generating system according to any of Examples 1-13, wherein the control circuit is configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on electricity supplied to the inductor coil during heating of the susceptor.

[0102] Example 15. An aerosol generating system according to any of Examples 1 to 14, wherein the control circuit is configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on electricity supplied to the inductor coil during a cooling period of the susceptor.

[0103] Example 16. The aerosol generating system of any of Examples 1-15, wherein the control circuit is configured to determine that the susceptor is being supplied with a liquid aerosol-forming substrate when a parameter indicative of a rate of change of temperature of the susceptor is less than a dry susceptor threshold.

[0104] Example 17. An aerosol generating system according to any of Examples 1 to 16, wherein the control circuit is configured to determine that the susceptor is not being supplied with a liquid aerosol-forming substrate when a parameter indicative of a rate of change of temperature of the susceptor is greater than a dry susceptor threshold.

[0105] Example 18. An aerosol generating system according to any of Examples 1 to 17, wherein the control circuit is configured to determine whether the liquid reservoir is depleted based on whether the susceptor is supplied with a liquid aerosol-forming substrate.

[0106] Example 19. An aerosol generating system according to any of Examples 1 to 18, wherein the control circuit is configured to determine that the liquid reservoir is depleted when the susceptor is not supplied with a liquid aerosol-forming substrate for a time period equal to or greater than a time threshold.

[0107] Example 20. The aerosol generating system of any of Examples 1-19, wherein the control circuit is configured to detect an abnormal condition based on whether a liquid aerosol-forming substrate is supplied to the susceptor.

[0108] Example 21. An aerosol generating system according to any of Examples 1 to 20, wherein the control circuit is configured to detect an abnormal condition when the susceptor is not supplied with a liquid aerosol-forming substrate for a time period less than a time threshold.

[0109] Example 22. The aerosol generating system of Example 19 or Example 21, wherein the time threshold is between 50 milliseconds and 1000 milliseconds.

[0110] Example 23. An aerosol generation system described in any one of Examples 20 to 22, wherein the control circuit is configured to determine a fault condition when an abnormal condition is detected at least twice.

[0111] Example 24. An aerosol generating system according to any of Examples 1 to 23, wherein the control circuit is configured to provide an indication to a user when it is determined that the susceptor is not supplied with a liquid aerosol-forming substrate.

[0112] Example 25. An aerosol generating system according to any of Examples 1 to 24, wherein the control circuit is configured to provide an indication to the user when the liquid reservoir is determined to be depleted.

[0113] Example 26. An aerosol generating system according to any one of Examples 1 to 25, wherein the control circuit is configured to provide an indication to a user when an abnormal condition is detected.

[0114] Example 27. An aerosol generating system according to any one of Examples 1 to 26, wherein the control circuit is configured to provide an indication to a user when a fault condition is detected.

[0115] Example 28. An aerosol generating system described in any one of Examples 24 to 27, wherein the control circuit is configured to provide an auditory indication to the user.

[0116] Example 29. An aerosol generating system described in any one of Examples 24 to 27, wherein the control circuit is configured to provide a visual indication to the user.

[0117] Example 30. An aerosol generating system described in any one of Examples 24 to 27, wherein the control circuitry is configured to provide a tactile indication to the user.

[0118] Example 31. The aerosol generation system of any of Examples 1-30, wherein the control circuit is configured to operate the aerosol generation system in a first mode and a second mode, the first mode being different from the second mode.

[0119] Example 32. An aerosol generation system as described in Example 31, wherein the first mode is a high power mode in which the control circuit can be configured to supply electricity to the inductor coil.

[0120] Example 33. The aerosol generating system of Example 31 or Example 32, wherein the second mode is a low power mode.

[0121] Example 34. The aerosol generation system of Example 33, wherein in a lower power mode, the control circuitry can be configured to prevent the supply of electricity to the inductor coil.

[0122] Example 35. An aerosol generation system as described in Example 33, wherein in the lower power mode, the control circuit is configured to supply a lower voltage of electricity to the inductor coil compared to the high power mode.

[0123] Example 36. The aerosol-generating system of any one of Examples 31 to 35, wherein the control circuit is configured to operate the aerosol-generating system in the first mode when the susceptor is supplied with a liquid aerosol-forming substrate.

[0124] Example 37. The aerosol-generating system of any one of Examples 31 to 36, wherein the control circuit is configured to operate the aerosol-generating system in the second mode when the susceptor is not supplied with a liquid aerosol-forming substrate.

[0125] Example 38. The aerosol generating system of any of Examples 1-37, comprising an information storage component configured to store the dry susceptor threshold.

[0126] Example 39. The aerosol generating system of Example 38, wherein the information storage component is an electronic memory.

[0127] Example 40. The aerosol generating system of Example 38, wherein the information storage component is an RFID (radio frequency identification) tag.

[0128] Example 41 The aerosol generating system of Example 38, wherein the information storage component is a one-dimensional barcode.

[0129] Example 42. The aerosol generating system of Example 28, wherein the information storage component is a two-component barcode.

[0130] Example 43. The aerosol generating system of any one of Examples 38-42, wherein the dry susceptor threshold is predetermined and stored on the information storage component.

[0131] Example 44. The aerosol generating system of any one of Examples 1 to 42, wherein the control circuitry is configured to determine a dry susceptor threshold.

[0132] Example 45. The aerosol generating system of Example 44, wherein the control circuit can be configured to determine the dry susceptor threshold based on the initial supply of electricity to the inductor coil.

[0133] Example 46. The aerosol generation system of example 45, wherein an initial supply of electricity is provided to the inductor coil when the aerosol generation system is first turned on.

[0134] Example 47. The aerosol generation system of Example 45, wherein an initial supply of electricity is supplied to the inductor coil when the first puff is taken with the aerosol generation system.

[0135] Example 48. An aerosol generating system described in any one of Examples 45 to 47, wherein the control circuit is configured to determine a parameter indicative of the initial rate of change of temperature of the susceptor based on the initial supply of electricity to the inductor coil.

[0136] Example 49. The aerosol-generating system of any one of Examples 45 to 48, wherein no liquid aerosol-forming substrate is supplied to the susceptor during the initial supply of electricity to the inductor coil.

[0137] Example 50. The aerosol generating system of Example 49, wherein the dry susceptor threshold is a parameter indicative of the initial rate of temperature change of the susceptor.

[0138] Example 51. The aerosol-generating system of any of Examples 1-50, comprising a wicking element arranged to convey the liquid aerosol-forming substrate from the liquid reservoir to the susceptor.

[0139] Example 52. The aerosol generating system of any one of Examples 1 to 51, wherein the susceptor is disposed substantially outside the liquid reservoir.

[0140] Example 53. The aerosol generating system of any of Examples 1-52, wherein the susceptor comprises a first susceptor element and a second susceptor element, the second susceptor element being spaced apart from the first susceptor element.

[0141] Example 54. The aerosol generating system of Example 53, wherein the wicking element is disposed in the space between the first susceptor element and the second susceptor element.

[0142] Example 55. The aerosol generating system of any one of Examples 1 to 54, wherein the susceptor comprises a mesh.

[0143] Example 56. An aerosol generating system according to any one of Examples 1 to 55, wherein the inductor coil is a helical coil.

[0144] Example 57. The aerosol generating system of Example 56, wherein the helical coil is formed from wire.

[0145] Example 58. The aerosol generating system of Example 57, wherein the wire has a circular cross section.

[0146] Example 59 The aerosol generating system of Example 57 or Example 58, wherein the wire is made of copper.

[0147] Example 60. An aerosol generating system according to any of Examples 1 to 59, wherein the inductor coil comprises a first inductor coil and a second inductor coil, the first inductor coil is configured to generate an alternating magnetic field for heating the susceptor, and the control circuit is configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on electricity supplied to the second inductor coil.

[0148] Example 61. The aerosol generating system of any one of Examples 1 to 60, wherein the power supply comprises a DC power supply.

[0149] Example 62. An aerosol generating system according to any one of Examples 1 to 61, comprising an aerosol generating device comprising a power source, an inductor coil, and a control circuit.

[0150] Example 63. An aerosol generating system according to any one of Examples 1 to 62, comprising a cartridge comprising a liquid reservoir and a susceptor.

[0151] Example 64. The aerosol generation system of Example 63, wherein the cartridge comprises an information storage component.

[0152] Example 65. An aerosol generating device for use in the aerosol generating system of any of Examples 1 to 63, comprising a power source, an inductor coil, and a control circuit.

[0153] Example 66. A method of controlling an aerosol-generating system comprising a liquid reservoir for storing a liquid aerosol-forming substrate, a susceptor for receiving a supply of the liquid aerosol-forming substrate, and an inductor coil, comprising: supplying electricity to an inductor coil; determining a parameter indicative of a rate of change of temperature of the susceptor based on the electricity supplied to the inductor coil; determining whether the susceptor is being supplied with a liquid aerosol-forming substrate based on a comparison of the dry susceptor threshold to a parameter indicative of a rate of change of temperature of the susceptor.

[0154] Example 67. The method of Example 66, further comprising operating the aerosol-generating system in a first mode when the susceptor is supplied with a liquid aerosol-forming substrate, and operating the aerosol-generating system in a second mode when the susceptor is not supplied with a liquid aerosol-forming substrate.

[0155] The embodiments will now be further described with reference to the figures. [Brief explanation of the drawings]

[0156] [Figure 1A] FIG. 1A shows a schematic cross-sectional view of an aerosol generation system according to an embodiment of the present disclosure. [Figure 1B] FIG. 1B shows a cross-sectional schematic view of the aerosol generation system of FIG. 1A, with the system in an in-use configuration. [Figure 2A] FIG. 2A shows a schematic cross-sectional view of the cartridge of FIGS. 1A and 1B. [Figure 2B] FIG. 2B shows a schematic cross-sectional view of the cartridge of FIG. 2A rotated 90 degrees about the central longitudinal axis of the cartridge. [Figure 3] FIG. 3 shows a block diagram of the electronic components of the aerosol generation system. [Figure 4A-4B] 4A and 4B show some components of the control circuit. [Figure 5] FIG. 5 illustrates a scenario in which the supply of liquid aerosol-forming substrate from the liquid reservoir to the susceptor may be interrupted. [Figure 6] FIG. 6 illustrates a scenario in which the supply of liquid aerosol-forming substrate from the liquid reservoir to the susceptor may be interrupted. [Figure 7] FIG. 7 illustrates a scenario in which the supply of liquid aerosol-forming substrate from the liquid reservoir to the susceptor may be interrupted. [Figure 8A] FIG. 8A shows a graph illustrating an example of the temperature change of a susceptor when a liquid aerosol-forming substrate is supplied to the susceptor and when a liquid aerosol-forming substrate is not supplied to the susceptor. [Figure 8B] FIG. 8B shows a graph illustrating the rate of change of the apparent ohmic resistance of the inductor coil associated with the temperature changes shown in FIG. 8A. [Figure 9A] FIG. 9A shows a graph illustrating the temperature change of the susceptor during heating of the susceptor. [Figure 9B] FIG. 9B shows a graph illustrating the rate of change of the apparent ohmic resistance of the inductor coil associated with the temperature changes shown in FIG. 9A. [Figure 10A] FIG. 10A shows a graph illustrating the temperature change of the susceptor during cooling of the susceptor. [Figure 10B] FIG. 10B shows a graph illustrating the rate of change of the apparent ohmic resistance of the inductor coil associated with the temperature changes shown in FIG. 10A. DETAILED DESCRIPTION OF THE INVENTION

[0157] FIG. 1A shows a schematic diagram of an aerosol generation system according to one embodiment of the present disclosure. The aerosol generation system includes a cartridge 10 and an aerosol generation device 60. The cartridge 10 can be received by the aerosol generation device 60. FIG. 1B shows a schematic diagram of the aerosol generation system of FIG. 1A, in which the cartridge 10 is received by the aerosol generation device 60. The aerosol generation system is portable and has a size comparable to that of a conventional cigar or cigarette.

[0158] The cartridge 10 has a mouth end and a connecting end. The connecting end is located opposite the mouth end. An outer housing 36 defines a mouth end air outlet 38 at the mouth end of the cartridge 10. The cartridge 10 may further include a mouthpiece at the mouth end. The connecting end is configured to connect the cartridge 10 to an aerosol generation device 60, as described in more detail below.

[0159] The outer housing 36 is formed from a moldable plastic material, such as polypropylene. The outer width of the outer housing 36 is greater at the mouth end of the cartridge 10 than at the connecting end. This forms a shoulder 37 between the mouth end and the connecting end. This allows the connecting end of the cartridge 10 to be received in a cavity 64 of the aerosol generation device 60, and the shoulder 37 to position the cartridge 10 in the correct position on the aerosol generation device 60. This also allows the mouth end of the cartridge 10 to remain outside the aerosol generation device 60, allowing the mouth end to conform to the external shape of the aerosol generation device 60.

[0160] The cartridge 10 further includes a liquid reservoir 44 for storing the liquid aerosol-forming substrate 42. The liquid reservoir 44 extends from the mouth end of the outer housing 36 to the connecting end of the outer housing 36 and includes an annular space defined by the outer housing 36. The annular space has an internal passageway 48 extending between the mouth end air outlet 38 and the open end of the internal passageway 26 of the susceptor holder 14.

[0161] The liquid reservoir 44 further includes two channels 45. The two channels 45 are defined between the inner surface of the outer housing 36 and the outer surface of the susceptor holder 14. The two channels 45 extend from an annular space defined by the outer housing 36 at the mouth end of the cartridge 10 to the connecting end of the cartridge 10. The two channels 45 extend on opposite sides of the internal passage 26 of the susceptor holder 14.

[0162] The susceptor holder 14 includes a base 30 that partially closes one end of the interior passage 26. The base 30 includes an air inlet 32 ​​that allows air to be drawn into the interior passage 26 through the partially closed end.

[0163] An air passageway is formed through the cartridge 10 by the internal passageway 26 of the susceptor holder 14 and the internal passageway 48 of the liquid reservoir 44. The air passageway extends from the air inlet 32 ​​in the base 30 of the susceptor holder 14, through the internal passageway 26 of the susceptor holder 14, through the internal passageway 48 of the liquid reservoir 44 to the mouth end air outlet 38. The air passageway allows air to be drawn through the cartridge 10 from the connection end to the mouth end.

[0164] The cartridge 10 includes a susceptor assembly 12 mounted within a susceptor holder 14. The susceptor assembly 12 and susceptor holder 14 are located toward the connecting end of the cartridge 10. The susceptor assembly 12 is planar and thin, having a thickness dimension that is substantially less than its length and width dimensions. The susceptor assembly 12 is shaped in a rectangular configuration.

[0165] The susceptor assembly 12 comprises a susceptor comprising a first susceptor element 16 and a second susceptor element 18. Of course, in other embodiments, the susceptor may comprise a single susceptor element.

[0166] The susceptor assembly 12 also includes a wicking element for transporting the liquid aerosol-forming substrate 42 from the liquid reservoir 44 to the susceptor. The wicking element includes a first wicking layer 20 and a second wicking layer 22. The susceptor assembly 12 further includes a spacer element, not shown in FIG. 1A . The first susceptor element 16, the second susceptor element 18, the first wicking layer 20, and the second wicking layer 22 each generally form a rectangular shape. Each susceptor layer has the same length and width dimensions. The width of the susceptor elements 16 and 18 is smaller than the width of the first wicking layer 20 and the second wicking layer 22. Therefore, the first wicking layer 20 and the second wicking layer 22 each include an outer exposed portion of the wicking element that protrudes into two channels 45 through openings in the sidewall of the susceptor holder 14. The first and second susceptor elements 16, 18 are substantially identical and comprise a sintered mesh formed from ferritic and austenitic stainless steel filaments. The first and second wicking layers 20, 22 comprise a porous body of cotton filaments. The wicking elements are configured to deliver a liquid aerosol-forming substrate 42 from the exposed outer surfaces of the first and second wicking layers 20, 22 to the first and second susceptor elements 16, 18.

[0167] The first and second susceptor elements 16, 18 are configured to be heated by penetration with an alternating magnetic field to vaporize the liquid aerosol-forming substrate 42. The wicking element contacts the susceptor holder 14 such that the susceptor holder 14 supports the susceptor assembly 12 in place within the cartridge 10.

[0168] The susceptor assembly 12 is disposed inside the interior passage 26 of the tubular susceptor holder 14 and extends in a plane parallel to the central longitudinal axis of the susceptor holder 14. The first susceptor element 16 and the second susceptor element 18 are disposed entirely within the interior passage 26 of the susceptor holder 14.

[0169] The aerosol generating device 60 includes a generally cylindrical housing 62 having a connecting end and a distal end opposite the connecting end. A cavity 64 for receiving the connecting end of the cartridge 10 is located at the connecting end of the device 60. An air inlet 65 is provided through the outer housing 62 at the base of the cavity 64 to allow ambient air to be drawn into the cavity 64 at the base.

[0170] The aerosol generating device 60 comprises an induction heating arrangement disposed within the device outer housing 62. The induction heating arrangement includes an inductor coil 90, a control circuit 70, and a power source 72. The power source 72 comprises a rechargeable nickel-cadmium battery that is rechargeable via an electrical connector (not shown) at the distal end of the device 60. The control circuit 70 is connected to the power source 72 and the inductor coil 90 such that the control circuit 70 controls the supply of electricity to the inductor coil 90. The control circuit 70 is configured to supply an alternating current to the inductor coil 90.

[0171] The inductor coil 90 is positioned around the susceptor assembly 12 when the cartridge 10 is received in the cavity 64, as shown in FIG. 1B. The inductor coil 90 has a size and shape that matches the size and shape of the heating area of ​​the susceptor element. The inductor coil 90 is made of copper wire with a circular cross-section and is disposed on a coil former element (not shown). The inductor coil 90 is a helical coil and has a circular cross-section when viewed parallel to the longitudinal axis of the aerosol generation device 60.

[0172] The inductor coil 90 is configured such that when an alternating current is supplied to the inductor coil, the inductor coil generates an alternating magnetic field in the region of the susceptor assembly 12 when the cartridge 10 is received in the cavity 64 .

[0173] The induction heating arrangement further includes a flux concentrator element 91. The flux concentrator element 91 has a larger radius than the inductor coil 90, and therefore partially surrounds the inductor coil 90. The flux concentrator element 91 is configured to reduce stray power losses from the generated magnetic field.

[0174] 1B shows a schematic diagram of the aerosol generation system of FIG. 1A, in which cartridge 10 is received within aerosol generating device 60. In operation, when a user draws on mouth-end air outlet 38 of cartridge 10, ambient air is drawn through air inlet 65 of the system into the base of cavity 64 and into cartridge 10 through air inlet 32 ​​in base 30 of cartridge 10. Ambient air flows through cartridge 10, from base 30 to mouth-end air outlet 38, through air passageways, and over and across susceptor assembly 12, particularly first susceptor element 16 and second susceptor element 18.

[0175] The control circuit 70 controls the supply of electricity from the power supply 72 to the inductor coil 90 when the system is activated. The control circuit 70 includes an airflow sensor 63. The airflow sensor 63 is in fluid communication with the path of ambient air drawn through the system by the user. The control circuit 70 supplies electricity to the inductor coil 90 when a user puff on the cartridge 10 is detected by the airflow sensor 63.

[0176] When the system is activated, an alternating current is established in the inductor coil 90, which generates an alternating magnetic field in the cavity 64 that penetrates the susceptor assembly 12, heating the susceptor, including the first susceptor element 16 and the second susceptor element 18. The liquid aerosol-forming substrate 42 in the two channels 45 is drawn into the susceptor assembly 12 through the wicking elements and into the susceptor. In particular, the liquid aerosol-forming substrate 32 is drawn through the first wicking layer 20 and the second wicking layer 22 to the first susceptor element 16 and the second susceptor element 18, respectively. The liquid aerosol-forming substrate 42 may also be transferred between the first wicking layer 20 and the second wicking layer 22 through the spacer elements. The liquid aerosol-forming substrate 42 in the susceptor is heated, and volatile compounds from the heated aerosol-forming substrate are released into the air passage of the cartridge 10, where they cool and form an aerosol. The aerosol is entrained in air drawn through the air passageway of the cartridge 10 and is drawn out of the cartridge 10 at the mouth-end air outlet 38 for inhalation by the user.

[0177] Figure 2A shows a schematic view of the cartridge 10 separated from the aerosol generating device, and Figure 2B shows a schematic view of the cartridge of Figure 2A rotated 90 degrees about the central longitudinal axis of the cartridge.

[0178] 2B illustrates the layered structure of the susceptor assembly 12 and illustrates a spacer element 24 positioned between and in contact with the first wicking layer 20 and the second wicking layer 22. The spacer element 24 is fluid permeable and configured to allow the liquid aerosol-forming substrate 42 to move between the first wicking layer 20 and the second wicking layer 22. The spacer element 24 generally forms a rectangular shape and has the same length and width dimensions as the first wicking layer 20 and the second wicking layer 22. The spacer element 24 comprises a porous body of cotton.

[0179] 3 shows a block diagram of the electronic components of the aerosol generation system. The aerosol generator 60 includes a DC power supply 72 (battery), a microcontroller 301, a DC / AC converter or inverter 302, a matching network 303 for load adaptation, and an inductor coil 90. The cartridge 10 includes a susceptor having a first susceptor element 16 and a second susceptor element 18. The microprocessor 301, the DC / AC converter or inverter 302, and the matching network 303 are all part of the power supply electronics 70. The DC supply voltage V DC and the current drawn from the DC power supply 72, I DC is provided by a feedback channel to the microcontroller 301. This allows the microcontroller 301 to DC and the current drawn I DC This also allows the microcontroller 301 to determine the AC power P to the inductor coil 90. AC This may allow for the further supply of

[0180] Of course, the matching network 303 may be provided for optimal matching to the load, but is not required. The matching network 303 may improve the power transfer efficiency between the DC / AC converter 302 and the inductor 90.

[0181] During operation of the aerosol generation system, the inductor coil 90 generates a high frequency alternating magnetic field that induces eddy currents in the susceptor, causing the susceptor to heat. As the susceptor heats up, the apparent ohmic resistance of the inductor coil increases as the temperature of the susceptor increases. This increase in apparent ohmic resistance of the inductor coil increases the current I drawn from the DC power supply 72. DCis detected by the control circuit 70 via a measurement of the apparent ohmic resistance of the inductor coil, which decreases as the temperature and apparent ohmic resistance of the inductor coil increase at a constant voltage. Thus, the rate of change of the susceptor temperature can be determined based on the rate of change of the apparent ohmic resistance of the inductor coil.

[0182] 4A shows some further components of the control circuit 70, and more particularly of the DC / AC converter 302. As can be seen in FIG. 4A, the DC / AC converter 302 comprises a class-E power amplifier including a transistor switch 3020 including a field effect transistor (FET) 3021, e.g., a metal oxide semiconductor field effect transistor (MOSFET), a transistor switch supply circuit indicated by arrow 3022 for supplying a switching signal (gate-source voltage) to the FET 3021, and an LC load network 3023 including a shunt capacitor C1 and a series connection of a capacitor C2 and an inductor L2 corresponding to the inductor coil 90. Additionally, during operation, a current I DC is derived from DC power supply 72, DC supply voltage V DC 4B, the ohmic resistance R represents the total ohmic load, which is the ohmic resistance R of inductor L2. coil and the ohmic resistance of the susceptor, R load The total ohmic load is the apparent ohmic resistance of the inductor coil 90. The ohmic resistance R of the inductor L2 coil does not change significantly during operation of the aerosol generation system. Therefore, the change in the total ohmic load (or apparent ohmic resistance) is proportional to the susceptor ohmic resistance R load This can be due to changes in

[0183] 5, 6, and 7 show diagrams of scenarios in which the supply of liquid aerosol-forming substrate 42 from liquid reservoir 44 to the susceptor may be insufficient to produce a satisfactory aerosol.

[0184] 5 shows a schematic cross-sectional view of the cartridge 10 of FIG. 1A with the liquid reservoir 44 empty. In this scenario, no liquid aerosol-forming substrate 42 is in contact with the first wicking layer 20 or the second wicking layer 22. Therefore, no liquid aerosol-forming substrate 42 is being supplied to the first susceptor element 16 or the second susceptor element 18.

[0185] 6 shows a schematic cross-sectional view of the cartridge 10 of FIG. 1A with the liquid reservoir 44 nearly empty. In this scenario, only a portion of the first wicking layer 20 and the second wicking layer 22 are in contact with the remaining liquid aerosol-forming substrate 42. This can lead to an insufficient supply of the liquid aerosol-forming substrate 42 to the first susceptor element 16 and the second susceptor element 18.

[0186] FIG. 7 shows a schematic cross-sectional view of the cartridge 10 of FIG. 1A in which, due to how the cartridge 10 is oriented, there is no liquid aerosol-forming substrate 42 in contact with the first wicking layer 20 or the second wicking layer 22. This can occur when the liquid reservoir 44 is partially depleted and the user holds the aerosol-generation system in a particular orientation, such as upside down. In this scenario, there is no liquid aerosol-forming substrate 42 supplied to the first susceptor element 16 or the second susceptor element 18. However, the interruption in the supply of liquid aerosol-forming substrate 42 to the first susceptor element 16 and the second susceptor element 18 may only be temporary. This is because the user can reorient the aerosol-generation system after a short period of time so that the liquid aerosol-forming substrate 42 is in contact with the first wicking layer 20 and the second wicking layer 22.

[0187] Of course, there are other scenarios in which the supply of liquid aerosol-forming substrate 42 to first and second susceptor elements 16, 18 may be temporarily interrupted or otherwise insufficient. For example, if a user puffs too hard on mouth-end air outlet 38, the liquid aerosol-forming substrate 42 may be aerosolized at a rate greater than the rate at which it is being supplied to first and second susceptor elements 16, 18.

[0188] By monitoring the susceptor temperature, particularly the susceptor temperature change rate, it is possible to detect whether the susceptor is being supplied with liquid aerosol-forming substrate 42 or not. This allows appropriate measures to be taken when it is detected that the susceptor is not being supplied with liquid aerosol-forming substrate. The susceptor temperature change rate can be monitored indirectly by monitoring the rate of change of the apparent ohmic resistance (or apparent conductance) of inductor coil 90.

[0189] Figure 8A shows a graph illustrating an example of the temperature change of a susceptor when the susceptor is supplied with a liquid aerosol-forming substrate 42 and when the susceptor is not supplied with a liquid aerosol-forming substrate 42. Figure 8B shows a graph illustrating the rate of change of the apparent ohmic resistance of the inductor coil 90 associated with the temperature change illustrated in Figure 8A.

[0190] 8A illustrates a first line 801 representing the temperature change of the susceptor as the susceptor is supplied with a liquid aerosol-forming substrate 42. At time t0, a user begins to puff on the aerosol-generating system. Thus, the control circuit 70 begins supplying electricity to the inductor coil 90, causing the temperature to change from a first temperature at time t0 to an operating temperature T O From time t2 to time t3, the control circuit 70 heats the susceptor to the operating temperature T OThe supply of electricity to the inductor coil 90 is controlled to maintain the temperature between time t2 and time t3. Although the temperature between time t2 and time t3 is shown as constant in FIG. 8A, this is for illustrative purposes. In reality, the susceptor cools and then returns to the operating temperature T O There will be a slight change in the temperature of the susceptor as it is reheated to maintain t The user stops priming the aerosol generating system at time t3, which causes control circuit 70 to stop supplying electricity to inductor coil 90, and the susceptor then begins to cool from time t3 to time t4.

[0191] 8A illustrates a second line 802 representing the temperature change of the susceptor when no liquid aerosol-forming substrate 42 is supplied to the susceptor. At time t0, a user begins puffing on the aerosol-generating system. Accordingly, the control circuit 70 begins supplying electricity to the inductor coil 90 to heat the susceptor. It can be seen that the susceptor heats up more quickly when no liquid aerosol-forming substrate is supplied to the susceptor compared to when the susceptor is supplied with a liquid aerosol-forming substrate. This is because the temperature of the susceptor changes from a first temperature at time t0 to an operating temperature T at time t1 (t1 being less than t2). O t3. This is because heat from the susceptor cannot be transferred to the liquid aerosol-forming substrate 42. The user stops purging the aerosol-generating system at time t3, which causes the control circuit 70 to stop supplying electricity to the inductor coil 90, after which the susceptor begins to cool from time t3 to time t4. It can be seen that the susceptor cools more slowly when the liquid aerosol-forming substrate 42 is not supplied to the susceptor compared to when the liquid aerosol-forming substrate 42 is supplied to the susceptor.

[0192] Figure 8B shows a first line 803 representing the rate of change of the apparent ohmic resistance of inductor coil 90 during the temperature change indicated by first line 801 in Figure 8A. Figure 8B also shows a second line 804 representing the rate of change of the apparent ohmic resistance of inductor coil 90 during the temperature change indicated by second line 802 in Figure 8A. The relationship between the apparent ohmic resistance of the inductor coil and the temperature of the susceptor is depicted as a straight line. However, it should be understood that other monotonic relationships between the apparent resistance of the inductor coil and the temperature of the susceptor are possible.

[0193] A first line 803 in FIG. 8B represents the rate of change of the apparent resistance of the inductor coil as the susceptor is heated from a first temperature to an operating temperature T O During this period, the rate of change of the apparent ohmic resistance is positive. However, the rate of change of the apparent ohmic resistance decreases as the temperature of the susceptor increases above the operating temperature T O The rate of change of apparent resistance decreases as time approaches t2. From time t2 to time t3, the rate of change of apparent resistance is approximately zero. However, as previously mentioned, there will be cooling and heating of the susceptor during this period. Therefore, the rate of change of apparent ohmic resistance of the inductor coil will fluctuate between positive, zero, and negative. From time t3 to t4, the rate of change of apparent ohmic resistance of the inductor coil is negative due to the cooling of the susceptor.

[0194] The second line 804 in Figure 8B indicates that the magnitude of the rate of change in the apparent ohmic resistance of the inductor coil during the period when the susceptor is heating is greater when no liquid aerosol-forming substrate is being supplied to the susceptor than when a liquid aerosol-forming substrate is being supplied to the susceptor. On the other hand, the second line 804 in Figure 8B indicates that the magnitude of the rate of change in the apparent ohmic resistance of the inductor coil during the period when the susceptor is cooling is smaller when no liquid aerosol-forming substrate is being supplied to the susceptor than when a liquid aerosol-forming substrate is being supplied to the susceptor. Therefore, by comparing the rate of change in the apparent ohmic resistance of the inductor coil with a dry susceptor threshold, it is possible to determine whether a liquid aerosol-forming substrate is being supplied to the susceptor. The dry susceptor threshold may be the rate of change in the apparent ohmic resistance of the inductor coil that indicates that no liquid aerosol-forming substrate is being supplied to the susceptor.

[0195] The DC supply voltage provided by power supply 72 is held constant. Thus, the apparent ohmic resistance of the inductor coil can be determined by measuring the current drawn by inductor coil 90. The apparent ohmic resistance of the inductor coil can then be determined using Ohm's Law. The rate of change of the apparent ohmic resistance can be determined by taking a first measurement of the apparent ohmic resistance at a first time point and a second measurement of the apparent ohmic resistance at a second time point. The time interval between the first and second measurements is preferably small.

[0196] During the period when the susceptor is being heated, electricity is already being supplied to the inductor coil 90. Thus, the current drawn during heating can be used to determine the apparent ohmic resistance of the inductor coil. However, at other times, it may be necessary to supply electricity to the inductor coil, particularly to enable the determination of the apparent ohmic resistance of the inductor coil. In this case, electricity should be supplied to the inductor coil for only short periods of time to avoid substantial heating of the susceptor.

[0197] FIG. 9A shows a graph illustrating the temperature change of the susceptor during heating of the susceptor. FIG. 9B shows a graph illustrating the rate of change of the apparent ohmic resistance of the inductor coil associated with the temperature change illustrated in FIG. 9A. Two scenarios are illustrated in FIGS. 9A and 9B. In the first scenario, the liquid reservoir 44 is depleted of liquid aerosol-forming substrate 42, as shown in FIG. 5, and as a result, liquid aerosol-forming substrate 42 is not being supplied to the susceptor. In the second scenario, the liquid reservoir 44 is not depleted of liquid aerosol-forming substrate 42, but the supply of liquid aerosol-forming substrate 42 to the susceptor is temporarily interrupted, as shown in FIG. 7.

[0198] 9A and 9B show a first heating stage of the susceptor from t0 to t1, a second heating stage of the susceptor from t1 to t2, and a third heating stage of the susceptor from t2 to t3.

[0199] In both scenarios, the rate of temperature rise of the susceptor, shown by line 911, during the first heating stage represents the susceptor being supplied with liquid aerosol-forming substrate 42. This is because the rate of change of the apparent ohmic resistance of the inductor coil, shown by line 921, exceeds the dry susceptor threshold R T Therefore, the rate of change of the apparent ohmic resistance of the inductor coil is expressed as the dry susceptor threshold R T By comparing the values ​​of the liquid aerosol-forming substrate and the liquid aerosol-forming substrate, the control circuit 70 determines that the susceptor is being supplied with a liquid aerosol-forming substrate during the first heating stage.

[0200] In both scenarios, the rate of temperature rise of the susceptor during the second heating stage, shown by line 912, represents a susceptor without a liquid aerosol-forming substrate 42 applied, because the rate of change of the apparent ohmic resistance of the inductor coil, shown by line 922, exceeds the dry susceptor threshold R T Therefore, the rate of change of the apparent resistance of the inductor coil is defined as the dry susceptor threshold R TBy comparing the values ​​of the liquid aerosol-forming substrate and the liquid aerosol-forming substrate, the control circuit 70 determines that the susceptor is not being supplied with a liquid aerosol-forming substrate during the second heating stage.

[0201] In the first scenario, the rate of temperature rise of the susceptor, shown by line 913, during the third heating stage represents a susceptor without a liquid aerosol-forming substrate 42 applied, as the rate of change of the apparent ohmic resistance of the inductor coil, shown by line 923, approaches the dry susceptor threshold R T However, in the second scenario, during the third heating stage, the rate at which the liquid aerosol-forming substrate 42 is being supplied is shown by the rate at which the apparent ohmic resistance of the inductor coil, shown by line 924, remains greater than the dry susceptor threshold R T is indicated by being less than

[0202] Control circuitry 70 is configured to distinguish between these two scenarios.

[0203] In a first scenario, the control circuit 70 is configured to determine that the liquid reservoir 44 is depleted when the susceptor has not been supplied with liquid aerosol-forming substrate 42 for a time period equal to or greater than a time threshold. In this case, the time threshold is equal to the length of time t1-t3, which is 100 milliseconds. The control circuit 70 may then be configured to stop supplying electricity to the inductor coil 90 until the cartridge 10 is replaced or refilled. Additionally or alternatively, the control circuit 70 may be configured to alert the user that the cartridge 10 needs to be replaced or refilled.

[0204] In a second scenario, the control circuit 70 is configured to detect a temporary interruption when the liquid aerosol-forming substrate 42 is not supplied to the susceptor for a time period shorter than a time threshold. The control circuit 70 may consider this to be an abnormal condition. The control circuit 70 may not take any action regarding the temporary interruption of the supply of the liquid aerosol-forming substrate 42 to the susceptor. Alternatively, the control circuit 70 may be configured to alert a user of the temporary interruption of the supply of the liquid aerosol-forming substrate to the susceptor.

[0205] FIG. 10A shows a graph illustrating the temperature change of the susceptor during a cooling period of the susceptor. FIG. 10B shows a graph illustrating the rate of change of the apparent ohmic resistance of the inductor coil associated with the temperature change illustrated in FIG. 10A. Similar to FIGS. 9A and 9B, there are two scenarios illustrated in FIGS. 10A and 10B. In the first scenario, the liquid reservoir 44 is depleted of liquid aerosol-forming substrate 42, as shown in FIG. 5, and as a result, no liquid aerosol-forming substrate is supplied to the susceptor. In the second scenario, the liquid reservoir 44 is not depleted of liquid aerosol-forming substrate 42, but the supply of liquid aerosol-forming substrate 42 to the susceptor is temporarily interrupted, as shown in FIG. 7.

[0206] 10A and 10B show a first cooling stage of the susceptor from t0 to t1, a second cooling stage of the susceptor from t1 to t2, and a third cooling stage of the susceptor from t2 to t3.

[0207] In both scenarios, the rate of temperature decrease of the susceptor, shown by line 1011, during the first cooling stage represents the susceptor being supplied with liquid aerosol-forming substrate 42. This occurs when the rate of change of the apparent ohmic resistance of the inductor coil, shown by line 1021, approaches the dry susceptor threshold R T Therefore, the rate of change of the apparent ohmic resistance of the inductor coil is expressed as the dry susceptor threshold R T By comparing the values ​​of the liquid aerosol-forming substrate 42 with the liquid aerosol-forming substrate 42, the control circuit 70 determines that the susceptor is being supplied with liquid aerosol-forming substrate 42 during the first cooling stage.

[0208] In both scenarios, the rate of temperature decrease of the susceptor during the second cooling stage, shown by line 1012, represents a susceptor without the liquid aerosol-forming substrate 42 applied, as the rate of change of the apparent ohmic resistance of the inductor coil, shown by line 1022, decreases below the dry susceptor threshold R T Therefore, the rate of change of the apparent resistance of the inductor coil is defined as the dry susceptor threshold R T By comparing the values ​​of the liquid aerosol-forming substrates, the control circuit 70 determines that the susceptor is not being supplied with liquid aerosol-forming substrate during the second period of cooling.

[0209] In the first scenario, the rate of temperature decrease of the susceptor, shown by line 1013, represents a susceptor without a liquid aerosol-forming substrate 42 applied, as the rate of change of the apparent ohmic resistance of the inductor coil, shown by line 1023, approaches the dry susceptor threshold R T However, in the second scenario, the rate of temperature decrease of the susceptor, shown by line 1014, represents a susceptor being supplied with a liquid aerosol-forming substrate 42. This occurs when the rate of change of the apparent ohmic resistance of the inductor coil, shown by line 1024, falls below the dry susceptor threshold R T is indicated by being less than

[0210] As described in connection with Figures 9A and 9B, control circuitry 70 is configured to distinguish between these two scenarios through the use of time thresholds.

[0211] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like are understood to be modified in all instances by the term "about." Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A ± 5%. Within this context, the number A may be considered to include a numerical value that is within the typical standard error for measurement of the property that the number A modifies. In some cases, as used in the appended claims, the number A may deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. 1. An aerosol generating system comprising: a liquid reservoir for storing the liquid aerosol-forming substrate; a susceptor for receiving a supply of liquid aerosol-forming substrate from the liquid reservoir and for heating the liquid aerosol-forming substrate to form an aerosol; an inductor coil configured to generate an alternating magnetic field for heating the susceptor; a power source configured to supply electricity to the inductor coil; a control circuit configured to determine a parameter indicative of a rate of change of temperature of the susceptor based on the electricity supplied to the inductor coil; Equipped with the control circuit is configured to determine whether the liquid aerosol-forming substrate is being supplied to the susceptor based on a comparison of a dry susceptor threshold value and the parameter indicative of the rate of change of temperature of the susceptor. Aerosol generation system.

2. 2. The aerosol generating system of claim 1, wherein the parameter indicative of the rate of change of the temperature of the susceptor is the rate of change of the apparent ohmic resistance of the inductor coil.

3. 3. The aerosol generating system of claim 1, wherein the parameter indicating the rate of change of temperature of the susceptor is based on a first measurement of the electricity supplied to the inductor coil and a second measurement of the electricity supplied to the inductor coil.

4. 4. The aerosol generating system of claim 3, wherein the first measurement and the second measurement are separated by a time interval, the time interval being less than 500 milliseconds.

5. An aerosol generation system as described in any one of claims 1 to 4, wherein the control circuit is configured to determine the parameter indicative of the rate of change of temperature of the susceptor based on the electricity supplied to the inductor coil during the cooling period of the susceptor.

6. 6. The aerosol generating system of claim 1, wherein the control circuit is configured to determine that the susceptor is not being supplied with a liquid aerosol-forming substrate when the parameter indicating the rate of change of temperature of the susceptor is greater than the dry susceptor threshold.

7. 7. The aerosol generating system of claim 1, wherein the control circuit is configured to determine whether the liquid reservoir is depleted based on whether a liquid aerosol-forming substrate is supplied to the susceptor.

8. 8. The aerosol generating system of claim 1, wherein the control circuit is configured to determine that the liquid reservoir is depleted when the susceptor is not supplied with a liquid aerosol-forming substrate for a time period equal to or greater than a time threshold.

9. 9. The aerosol generating system of claim 1, wherein the control circuit is configured to detect an abnormal condition when the liquid aerosol-forming substrate is not supplied to the susceptor for a time period less than a time threshold.

10. 10. The aerosol generation system according to claim 1, wherein the control circuit is configured to operate the aerosol generation system in a first mode and a second mode, the first mode being different from the second mode, the control circuit being configured to operate the aerosol generation system in the first mode when a liquid aerosol-forming substrate is supplied to the susceptor, and the control circuit being configured to operate the aerosol generation system in the second mode when a liquid aerosol-forming substrate is not supplied to the susceptor.

11. 11. The aerosol generation system of claim 1, wherein the control circuit is configured to determine the dry susceptor threshold based on an initial supply of electricity to the inductor coil.

12. 12. The aerosol generating system of claim 11, wherein the susceptor is not supplied with a liquid aerosol-forming substrate during the initial supply of electricity to the inductor coil.

13. 13. The aerosol generation system of claim 12, wherein the control circuit is configured to determine a parameter indicative of an initial rate of temperature change of the susceptor based on the initial supply of electricity to the inductor coil, and the dry susceptor threshold is a parameter indicative of the initial rate of temperature change of the susceptor.

14. 14. The aerosol generating system according to any one of claims 1 to 13, wherein the susceptor is in the form of a mesh.

15. 1. A method of controlling an aerosol-generating system comprising: a liquid reservoir for storing a liquid aerosol-forming substrate; a susceptor for receiving a supply of said liquid aerosol-forming substrate; and an inductor coil configured to generate an alternating magnetic field for heating said susceptor, comprising: supplying electricity to the inductor coil; determining a parameter indicative of a rate of change of temperature of the susceptor based on the electricity supplied to the inductor coil; determining whether the susceptor is being supplied with the liquid aerosol-forming substrate based on a comparison of the parameter indicative of the rate of change of temperature of the susceptor to a dry susceptor threshold; A method comprising:

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