Aerosol generation system and method for controlling the power supplied to a heater

Abstract

Aerosol generating system comprising: a DC power supply (202) for generating a DC supply voltage; a control circuit for controlling the supply of power from the DC power supply (202) to a heater (204) for aerosolizing a liquid aerosol-forming substrate, wherein the control circuit comprises: a DC / DC voltage converter (206) disposed to receive the DC supply voltage as input and output an output voltage for supplying power to the heater (204); and a control unit (210) configured to control the DC / DC voltage converter (206) to adjust the output voltage based on a predetermined power profile of the heater, wherein the predetermined power profile includes a first period in which a first power value is supplied to the heater (204) and a second period after the first period in which a second power value is supplied to the heater (204), the second power value being smaller than the first power value.

Description

[Technical Field]

[0001] This disclosure relates to an aerosol generating system, and more particularly to power control for a heater in a handheld, electrically operated aerosol generating system. The aerosol generating device may be configured to heat an aerosol-forming substrate to generate an aerosol and deliver the aerosol into the user's mouth. This disclosure further relates to a method for power control in an aerosol generating system. [Background technology]

[0002] Aerosol generating systems that heat a liquid aerosol-forming substrate to generate an aerosol to be delivered to a user are generally known in the prior art. Such systems typically comprise a component for holding the liquid aerosol-forming substrate, a heater for heating the substrate, and a power source, such as a battery, for supplying current to the heater. In one known type of aerosol generating system, the heater comprises a resistive heating element wound around a wick that supplies the liquid aerosol-forming substrate to a heating element. When a user inhales from the aerosol generating system, current flows through the heating element, heating it by resistive or Joule heating, and consequently heating the liquid aerosol-forming substrate supplied by the wick. This releases volatile compounds from the liquid aerosol-forming substrate, which cool and form an aerosol. The aerosol is then inhaled into the user's mouth through a mouthpiece. Another known type of aerosol generating system uses induction heating to heat the aerosol-forming substrate. In induction heating systems, the heater typically comprises a susceptor that is in thermal contact with the aerosol-forming substrate, which is inductively heated by an induction coil.

[0003] Increasing market pressure to reduce the cost of aerosol generating systems, along with growing environmental and legal pressures to provide sustainable and reusable products, is driving the demand for heaters in aerosol generating systems designed to withstand tens of thousands of smoke inhalations. This requires heaters that are more mechanically and thermally robust. Increasing the robustness of resistance heaters generally involves increasing the cross-sectional area of ​​the heater's conductor. However, such an increase in cross-sectional area has the adverse effect of reducing the electrical resistance of the heater element. Increasing the length of the heater to increase its resistance is often impossible due to the geometric constraints of the heating area. Similar problems are also encountered in induction heating systems, which typically have low resistance due to their structure.

[0004] The problem with reducing the electrical resistance of a heater in an aerosol generation system is that, assuming the same voltage is applied, the amount of current drawn from the battery increases. In particular, the instantaneous current supplied by the battery can increase significantly by reducing the heater resistance, for example, when the current is first supplied to the heater. Excessive current can damage the battery by overheating and can increase power loss in the electrical connections leading to the heater, especially if the resistance of the electrical connections is equal to the resistance of the heater.

[0005] It is desirable to provide an aerosol generation system that has the ability to reduce the current drawn from the power supply, especially when using a heater with reduced resistance. It is also desirable to provide a method for controlling an aerosol generation system that reduces the current drawn from the power supply, especially when using a heater with reduced resistance. [Overview of the Initiative]

[0006] An aerosol generation system is provided according to one embodiment of the present disclosure. The aerosol generation system may include a DC power supply. The DC power supply may generate a DC supply voltage. The aerosol generation system may include a control circuit. The control circuit may control the supply of power from the DC power supply to a heater for aerosolization of a liquid aerosol-forming substrate. The control circuit may include a DC / DC voltage converter. The DC / DC voltage converter may be configured to receive a DC supply voltage as input. The DC / DC voltage converter may be configured to output an output voltage for powering a heater. The control circuit may include a control unit. The control unit may be configured to control the DC / DC voltage converter to adjust the output voltage based on a predetermined power profile of the heater.

[0007] An embodiment of the present disclosure provides an aerosol generation system comprising a DC power supply for generating a DC supply voltage and a control circuit for controlling the supply of power from the DC power supply to a heater for aerosolizing a liquid aerosol-forming substrate. The control circuit includes a DC / DC voltage converter configured to take the DC supply voltage as input and output an output voltage for powering the heater. The control circuit further includes a control unit configured to control the DC / DC voltage converter to adjust the output voltage based on a predetermined power profile of the heater.

[0008] As used herein, the term “power profile” generally refers to the power applied to the heater during a heating cycle or while the user is smoking.

[0009] Advantageously, by providing a DC / DC voltage converter to adjust the output voltage based on a predetermined power profile of the heater, the voltage provided to the heater can be reduced. This means that the power supplied to the heater can be controlled by a continuous but lower DC voltage instead of using a higher DC voltage that is switched or cut off, for example, by using pulse width modulation (PWM). The DC / DC voltage converter can help reduce the instantaneous current drawn from the DC power supply, particularly the high instantaneous current that can be drawn when using PWM without reducing the output voltage applied to the heater at all. Reducing the instantaneous current drawn from the DC power supply can help reduce the heating of the DC power supply. Further, the DC / DC voltage converter can help avoid potentially high amplitude current peaks within the heater and reduce heat dissipation in the connections or lead tracks to the heater. Additionally, the aerosol generation system of the present disclosure can help extend the life of the heater as the thermal stress and electromigration effects are low.

[0010] Advantageously, by controlling a DC / DC voltage converter to adjust the output voltage based on a predetermined power profile of the heater, as further discussed below with respect to FIG. 1, the temperature of the heater can be regulated by the boiling point of the liquid substrate. In other words, the power supplied to the heater drives the throughput of the aerosolized liquid aerosol-forming substrate. As a result, the aerosol generation system of the present disclosure does not need to control the heater to follow a predetermined temperature profile when aerosolizing the liquid aerosol-forming substrate. This means that the design of the system can be simplified and does not require components such as temperature sensors.

[0011] The DC / DC voltage converter may be a step-down converter or a buck converter such that the output voltage is smaller than the DC supply voltage. Advantageously, the buck converter helps ensure voltage reduction, thereby reducing the instantaneous current drawn from the DC power supply and reducing the heating of the DC power supply.

[0012] The DC / DC voltage converter may be disposed between the DC power supply and the resistance heater.

[0013] The DC / DC voltage converter may include a first switching element. The control unit may be configured to provide a first switching signal to the first switching element to operate the first switching element. During use, the output voltage of the DC / DC voltage converter may be related to the duty cycle of the first switching signal.

[0014] The DC / DC voltage converter may include a second switching element. The control unit may be configured to provide a second switching signal to the second switching element to operate the second switching element. The second switching signal may be opposite to the first switching signal such that when the first switching element is activated, the second switching element is deactivated, and when the second switching element is activated, the first switching element is deactivated.

[0015] The DC / DC voltage converter may include an asynchronous DC / DC voltage converter. The first switching element may include a transistor. The second switching element may include a diode.

[0016] The DC / DC voltage converter may include a synchronous DC / DC voltage converter. The first and second switching elements may include transistors. The transistors may be field effect transistors. The transistors may be metal oxide semiconductor field effect transistors. The transistors may be N-channel metal oxide semiconductor field effect transistors.

[0017] The DC / DC voltage converter may include an inductor. The DC / DC voltage converter may include a capacitor. The inductor and the capacitor may be arranged to provide a DC output voltage.

[0018] The control circuit may further include a rectifier or filter. The rectifier or filter may be configured to reduce ripple in the DC output voltage.

[0019] The heater may be a resistance heater. A well-known aerosol generating system typically uses a resistance heater with a resistance of at least 1 ohm at room temperature to avoid excessive current drawn from the battery and to ensure safe operation. The resistance heater of the aerosol generating system of this disclosure may have an electrical resistance of less than 1 ohm, preferably less than 0.5 ohms, at room temperature. The resistance heater of the aerosol generating system of this disclosure may have an electrical resistance of 0.2 to 1 ohm at room temperature. More specifically, the resistance heater may have an electrical resistance of 0.2 to 0.5 ohms at room temperature.

[0020] As used herein, the term “room temperature” means a temperature in the range of 15 to 30 degrees Celsius, preferably in the range of 20 to 25 degrees Celsius, and more preferably about 20 degrees Celsius. Advantageously, the aerosol generating systems of this disclosure allow for the use of resistance heaters with reduced resistance compared to known resistance heaters, and thus allow for the use of more robust heaters.

[0021] The heater may include an electrically resistive heating element. The heating element may be made from any suitable conductive material. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilide), carbon, graphite, metals, alloys, and composite materials made of ceramic and metallic materials. Such composite materials may include doped or undoped ceramics. A suitable example of a doped ceramic is doped silicon carbide. Suitable examples of metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable metal alloys include stainless steel, constantan, nickel-containing, cobalt-containing, chromium-containing, aluminum-containing, titanium-containing, zirconium-containing, hafnium-containing, niobium-containing, molybdenum-containing, tantalum-containing, tungsten-containing, tin-containing, gallium-containing, manganese-containing, and iron-containing alloys, as well as nickel, iron, cobalt, and stainless steel-based superalloys, Timetal®, Inconel®, Kanthal®, iron-aluminum alloys, and iron-manganese-aluminum alloys. Timetal® is a registered trademark of Titanium Metals Corporation. Inconel® is a registered trademark of Special Metals Corporation. Kanthal® is a registered trademark of Kanthal AB. The heating element may be made from stainless steel, such as 300 series stainless steels like AISI 304, 316, 304L, and 316L.

[0022] The heating element may be made of a material with a high Young's modulus, such as tungsten. Preferably, the heating element is made of a material that is corrosion-resistant to the liquid aerosol-forming substrate.

[0023] In one embodiment, the heating element may be made of an electroceramic, including but not limited to MoSi2, doped SiC, indium tin oxide (ITO), lanthanum-doped strontium titanate (SLT), yttrium-doped strontium titanate, or a combination thereof.

[0024] The heater may be an induction heater. The induction heater may include an inductor. The inductor may include an induction coil. The induction heater may include a heating element in the form of a susceptor. The inductor may be configured to generate an alternating magnetic field for heating the susceptor and generating an aerosol from a liquid aerosol-forming substrate supplied to the susceptor. The susceptor may be arranged to be heated by the inductor.

[0025] As used herein, the term “susceptor” means an element that can be heated by penetration through an alternating magnetic field. A susceptor is typically heated by Joule heating through eddy current induction of the susceptor and at least one of hysteresis losses.

[0026] The induction heater may have an impedance or equivalent resistance of less than 1 ohm, preferably less than 0.5 ohms, at room temperature. The induction heater may have an impedance or equivalent resistance of 0.2 to 1 ohm at room temperature. More specifically, the induction heater may have an impedance or equivalent resistance of 0.2 to 0.5 ohms at room temperature. Advantageously, the aerosol generating system of this disclosure allows the use of induction heaters with relatively low impedance or equivalent resistance.

[0027] Where used herein, the term “equivalent resistance” refers to the resistance of an induction heater as “observed” by the electrical circuit during its operation. Equivalent resistance includes the apparent resistance of the susceptor and the resistance loss in the inductor windings in series. Therefore, the equivalent series resistance of an inductor is equal to the sum of the resistance loss in the inductor windings and the apparent resistance of the susceptor. Resistance loss in the coil windings, particularly at the inductor’s operating frequency, is primarily due to skin effect losses in the inductor windings. The apparent resistance of the susceptor is the additional resistance observed by the electrical circuit when the susceptor is inductively coupled to the inductor, and is primarily due to eddy currents and hysteresis losses within the susceptor. In circuit diagrams, equivalent resistance is depicted as the resistance in series with the inductor.

[0028] The susceptor may comprise a magnetic material that can be heated by penetration by an alternating magnetic field. The term “magnetic material,” as used herein, is used to describe a material that can interact with a magnetic field, including both paramagnetic and ferromagnetic materials. The magnetic material may be any suitable magnetic material that can be heated by penetration by an alternating magnetic field. In some preferred embodiments, the magnetic material includes ferritic stainless steel. Suitable ferritic stainless steels include SAE 400 series stainless steels such as SAE types 409, 410, 420, and 430 stainless steels.

[0029] If the aerosol generating system includes an induction heater, the control circuit may be configured to supply an alternating current to the inductor. As used herein, “alternating current” means a current that periodically reverses direction. The alternating current may have any suitable frequency. Suitable frequencies for the alternating current may be between 100 kilohertz (kHz) and 30 megahertz (MHz). If the inductor is a helical inductor coil or a tubular inductor coil, the alternating current may have a frequency between 500 kilohertz (kHz) and 30 megahertz (MHz). If the inductor is a flat inductor coil, the alternating current may have a frequency between 100 kilohertz (kHz) and 1 megahertz (MHz).

[0030] When an alternating current is driven through an inductor, the inductor generates an alternating magnetic field. This alternating magnetic field may have any suitable frequency for heating the heating portion of a susceptor element located within the alternating magnetic field. A suitable frequency for the alternating magnetic field may be between 100 kilohertz (kHz) and 30 megahertz (MHz).

[0031] If the aerosol generating system includes an induction heater, the control circuit may further include a DC / AC converter for supplying AC current to the inductor. The DC / AC converter may be located between the DC power supply and the inductor. The DC / AC converter may include a capacitor. The DC / AC converter may include an LC (inductor-capacitor) load network. In a preferred embodiment, the LC load network includes an inductor used to heat the susceptor and a capacitor. The inductor may be connected in series with the capacitor. In some embodiments, the inductor may be powered by a Class E or Class D power amplifier.

[0032] A DC / DC voltage converter may be positioned before a DC / AC converter to reduce the DC supply voltage so that the DC-to-AC conversion is performed at a reduced DC supply voltage. This arrangement helps reduce the current drawn when applying the DC-to-AC conversion, i.e., it helps avoid excessively high currents or current spikes when converting from DC to AC, and it can also help reduce switching losses because a lower voltage is switched in the DC-to-AC conversion.

[0033] In one embodiment of the present disclosure, the control circuit does not need to include a DC / DC voltage converter. The control unit may be configured to control the power supplied to the inductor based on a predetermined power profile of the induction heater by adjusting the frequency of the AC current supplied to the inductor. The control unit may also be configured to increase the frequency of the AC current supplied to the inductor to reduce the current in the induction heater, thereby reducing the power supplied to the heater.

[0034] For either induction heaters or resistance heaters, the heating element may have any suitable form. The heating element may include, for example, a mesh, a flat spiral coil, fibers, or cloth. The heating element may be fluid permeable.

[0035] In some preferred embodiments, the heating element is planar. The planar heating element may extend substantially in a plane.

[0036] In some preferred examples, the heating element comprises a mesh. The heating element may comprise an array of filaments forming a mesh. As used herein, the term “mesh” encompasses grids and arrays of filaments with spaces between them. The term mesh also includes woven and nonwoven fabrics.

[0037] The filaments may be formed by etching a sheet material such as foil. This can be particularly advantageous when the heater includes a series of parallel filaments. If the heating element includes a mesh or cloth of filaments, the filaments may be formed individually or woven together.

[0038] Preferably, the mesh is sintered. The filaments of the mesh may be sintered together. Advantageously, sintering the mesh creates electrical bonds between filaments extending in different directions. In particular, if the mesh contains one or more woven and nonwoven fabrics, it is advantageous to sinter the mesh so that electrical bonds are created between overlapping filaments.

[0039] The heater may further comprise a liquid delivery element. The liquid delivery element may be in fluid communication with a heating element. The liquid delivery element may be in fluid communication with a liquid storage portion for storing or holding a liquid aerosol-forming substrate. The liquid delivery element may be arranged to transport the liquid aerosol-forming substrate from the liquid storage portion to the heating element. In particular, the liquid delivery element may be arranged to transport the liquid aerosol-forming substrate from the liquid storage portion across the main surface of the heating element. The heating element may be fixed to the liquid delivery element. The heating element may be integrated with the liquid delivery element. Advantageously, the provision of a liquid delivery element improves wetting of the heating element, thereby increasing aerosol generation by the system.

[0040] In some preferred embodiments, the liquid delivery element is a wicking element. The wicking element may make it possible to fabricate a heating element from a material that does not itself provide good wicking or wetting properties.

[0041] The heater may comprise multiple heating elements. If the heater comprises multiple heating elements and a liquid delivery element, each heating element may be arranged in fluid communication with the liquid delivery element. The heater may comprise multiple heating elements and multiple liquid delivery elements.

[0042] In one embodiment, the heater comprises a first heating element and a second heating element, the second heating element separated from the first heating element by a gap. A liquid delivery element may be disposed in the space between the first and second heating elements. In some particularly preferred embodiments, the first heating element, the second heating element, and the liquid delivery element are substantially planar, with the first heating element disposed on a first side of the planar liquid delivery element and the second heating element disposed on a second side of the planar liquid delivery element opposite to the first side.

[0043] In an induction heating aerosol generation system, the heater may be a susceptor assembly, and the heating element may be replaced by a susceptor.

[0044] The liquid delivery element may include a capillary material. A capillary material is a material that has the ability to move liquid from one end to the other by capillary action. The capillary material may have a fibrous or spongy structure. Preferably, the capillary material includes bundles of capillaries. For example, the capillary material may include multiple fibers or threads, or other microtubules. The fibers or threads may generally be aligned to carry the liquid aerosol-forming substrate toward the heating element. In some embodiments, the capillary material may include a spongy or foamy material. The structure of the capillary material may form multiple small holes or tubes through which the liquid aerosol-forming substrate can move by capillary action. If the susceptor element has gaps or openings, the capillary material may extend into the gaps or openings within the susceptor element. The susceptor element may draw the liquid aerosol-forming substrate into the gaps or openings by capillary action.

[0045] The liquid delivery element may contain an electrically insulating material. The liquid delivery element may contain a thermal insulating material. The liquid delivery element may contain a hydrophilic material. The liquid delivery element may contain a lipophilic material. Advantageously, forming the liquid delivery element from a hydrophilic or lipophilic material may facilitate the transport of the liquid aerosol-forming substrate through the liquid delivery element.

[0046] The liquid delivery element may include non-metallic materials. Examples of suitable materials for the liquid delivery element include sponge or foam materials, ceramic or graphite-based materials in the form of fibers or sintered powders, foamed metal or plastic materials, fibrous materials, such as fibrous materials made from spun or extruded fibers (e.g., cellulose acetate, polyester, or bonded polyolefins, polyethylene, terylene, or polypropylene fibers, nylon fibers, or ceramic or glass fibers). Suitable materials for the liquid delivery element may include cellulose-based materials such as cotton or rayon. Preferably, the liquid delivery element may include rayon. The liquid delivery element may consist of rayon. A liquid delivery element containing a porous ceramic material may be particularly advantageous if at least one heating element includes a conductive material deposited on the liquid delivery element. A liquid delivery element containing a porous ceramic material may be an advantageous substrate for manufacturing processes associated with the deposition of conductive materials.

[0047] In some embodiments, the heater may be part of the aerosol generator rather than a cartridge. In such embodiments, the cartridge may be configured, for example, to deliver the aerosol-forming substrate to the heater in the device using a liquid delivery element.

[0048] Liquid delivery elements may rely on gravity for liquid delivery. Liquid delivery elements may include a pump.

[0049] A predetermined power profile may include a first period during which a first power value is supplied to the heater. The first power value may be configured to heat the heater at a predetermined rate.

[0050] A given power profile may include a second period during which a second power value is supplied to the heater. The second period may follow the first period. The second power value may be different from the first power value. The second power value may be less than the first power value.

[0051] The second power value may include the target power supplied to the heater.

[0052] The second power value may be configured to maintain the heater at a temperature higher than or approximately the same as the boiling point of the liquid aerosol-forming substrate.

[0053] Advantageously, by providing a predetermined power profile including a first power value and a second power value, the power supplied to the heater can be customized to the heater's requirements during different stages of the heating cycle or user fumigation. For example, the first power value may be higher than the second power value to heat the heater to the aerosolization temperature more quickly than if a constant amount of power were supplied at the second power value for the duration of the heating cycle or fumigation. After a first period in which the first power value is supplied to the heater, the power can be reduced to the second power value to maintain the heater at or near the boiling point of the aerosol-forming substrate. This can improve the efficiency of the aerosol generation system and avoid overheating of the heater. The first and second periods and the first and second power values ​​for a particular heater can be predetermined and stored within the control unit, so that the heater temperature does not need to be monitored, and the heater can be controlled based solely on the predetermined power profile.

[0054] The control unit may be configured to switch from a first power value to a second power value without using a temperature sensor. In other words, no temperature sensor or data is used to determine the first period. Instead, the switch from the first power value to the second power value may be based solely on power delivery, e.g., feedback voltage or feedback current. Advantageously, this helps reduce the number of components used in the aerosol generation system and also lowers manufacturing costs.

[0055] The control unit may be configured to switch from a first power value to a second power value based on a predetermined first period. The predetermined first period may be stored in memory.

[0056] The second power value may be configured to heat the heater such that the aerosolization rate of the liquid aerosol-forming substrate from the heater is less than or equal to the liquid flow rate of the liquid aerosol-forming substrate in the liquid delivery element of the heater. This helps to ensure that the volume of the porous or liquid-permeable portion of the liquid delivery element remains completely or substantially immersed with the liquid aerosol-forming substrate. Advantageously, this can help to ensure a sufficient supply of the liquid aerosol-forming substrate to the heater during a heating cycle or fume extraction, so that the supply of liquid to the heater can help regulate the heater temperature and avoid overheating.

[0057] The first power value may be in the range of 6 to 10 watts, preferably 7 to 9 watts. The second power value may be in the range of 4 to 7 watts. These have been found to be particularly suitable first and second power values.

[0058] The control circuit may further include a memory for storing predetermined power profiles. The control circuit may be configured to access the memory and retrieve an appropriate predetermined power profile depending on the heater and liquid aerosol-forming substrate used. The memory may store first and second power values. The first and second power values ​​may be stored in a lookup table. The control circuit may be configured to access the lookup table, retrieve the first and second power values, and control the DC / DC voltage converter to apply the predetermined power profile to the heater.

[0059] The control unit may be configured to control the DC / DC voltage converter without using a temperature sensor or resistance measuring sensor. Advantageously, this helps simplify the design and manufacture of the aerosol generation system by reducing the number of components.

[0060] The control unit may be configured to control the DC / DC voltage converter using closed-loop proportional-integral-derivative (PID) control to adjust the output voltage based on a predetermined power profile of the heater.

[0061] The aerosol generation system may further include a power metering unit for determining the power supplied to the heater. The power metering unit may be connected to a control unit, allowing the control unit to control a DC / DC voltage converter based on one or more signals received from the power metering unit. Advantageously, the power metering unit can help ensure that the aerosol generation system is supplying the heater with the correct amount of power according to a given power profile.

[0062] The power measurement unit may be configured to measure the current flowing through the resistive heater and the voltage across the resistive heater so that the control unit can determine or calculate the power.

[0063] The power measurement unit may include a shunt resistor. The shunt resistor may be connected in series with the heater. The power measurement unit may include an operational amplifier. The operational amplifier may have an input connected to both ends of the shunt resistor and be able to measure the voltage across the shunt resistor. The operational amplifier may have an output connected to a control unit. The shunt resistor may have a predetermined resistance value. The shunt resistor may have a resistance of less than 20 milliohms, preferably less than 10 milliohms, and more preferably less than 5 milliohms. The power measurement unit may be configured to determine the current flowing through the heater based on the voltage across the shunt resistor and the predetermined resistance value of the shunt resistor.

[0064] In one embodiment, the heater may include a shunt resistor. The operational amplifier may be configured to measure the voltage across the heater.

[0065] The power measurement unit may be configured to directly measure the voltage across the heater. The voltage measurement component of the power measurement unit may be directly connected to the input of the control unit, preferably to the analog-to-digital converter (ADC) input of the control unit.

[0066] The power measurement unit may include a voltage or potential divider for measuring the voltage across the heater.

[0067] An aerosol generation system may comprise an aerosol generator and a cartridge. The cartridge may be detachably coupled to the aerosol generator. The cartridge may include a liquid storage portion or reservoir configured to hold a liquid aerosol-forming substrate.

[0068] As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form aerosols. The volatile compounds may be released by heating the liquid aerosol-forming substrate.

[0069] The aerosol-forming substrate may be liquid at room temperature. The aerosol-forming substrate may comprise both a liquid component and a solid component. The liquid aerosol-forming substrate may contain nicotine. The nicotine-containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may contain plant-derived materials. The liquid aerosol-forming substrate may contain tobacco. The liquid aerosol-forming substrate may contain tobacco-containing materials that include volatile tobacco-flavored compounds released from the aerosol-forming substrate upon heating. The liquid aerosol-forming substrate may contain homogenized tobacco materials. The liquid aerosol-forming substrate may contain non-tobacco-containing materials. The liquid aerosol-forming substrate may contain homogenized plant-derived materials.

[0070] A liquid aerosol-forming substrate may comprise one or more aerosol-forming elements. An aerosol-forming element is any suitable known compound, or mixture of compounds, that facilitates the formation of a high-density, stable aerosol during use and is substantially resistant to thermal decomposition at the system's operating temperature. Examples of suitable aerosol-forming elements include glycerin and propylene glycol. Suitable aerosol-forming elements 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 acids, dicarboxylic acids, or polycarboxylic acids (e.g., dimethyl dodecanediol, dimethyl tetradecanediol). The liquid aerosol-forming substrate may also contain water, a solvent, ethanol, plant extracts, and natural or artificial flavors.

[0071] The liquid aerosol-forming substrate may contain nicotine and at least one aerosol-forming agent. The aerosol-forming agent may be glycerin or propylene glycol. The aerosol-forming agent may contain 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%.

[0072] The cartridge may include a cartridge housing. The cartridge housing may be formed from a durable material. The cartridge housing may be formed from a liquid-impermeable material. The cartridge housing may be formed from a moldable plastic material such as polypropylene (PP) or polyethylene terephthalate (PET). The cartridge housing of the cartridge may define a liquid storage portion or part of a reservoir. The cartridge housing may define a liquid storage portion. The cartridge housing and the liquid storage portion may be formed integrally. Alternatively, the liquid storage portion may be formed separately from the outer housing or disposed within the outer housing.

[0073] The aerosol generator may be equipped with a DC power supply. The aerosol generator may be equipped with a control circuit. The cartridge may be detachably coupled to the aerosol generator.

[0074] The aerosol generator may include a housing. The housing may be elongated. The housing may contain any suitable material or a combination of such materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of these materials, or thermoplastic resins suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably lightweight and non-brittle.

[0075] The aerosol generator housing may define a cavity for receiving at least a portion of the cartridge. The aerosol generator may have a connecting terminal configured to connect the aerosol generator to the cartridge. The connecting terminal may include a cavity for receiving the cartridge.

[0076] The control unit may include any suitable controller or electrical component. The control unit may include memory. Information for carrying out the methods described later may be stored in the memory. The control unit may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), or other electronic circuit capable of providing control. The control circuit may be configured to supply power to the heating element continuously after the device is started, or to supply power intermittently, such as with each smoke extraction.

[0077] Power may be supplied to the heating element in the form of current pulses, for example, by pulse width modulation (PWM). The control circuit may include a switching element for supplying switched current pulses to the heater. The switching element may be located after the DC / DC voltage converter so that the switching element receives a reduced DC voltage lower than the DC supply voltage of the DC power supply. The switching element may perform switching or disconnecting operations to a reduced DC voltage, for example, PWM, and then the switched or disconnected reduced DC voltage may be supplied to the heater. Thus, the switching element may help to provide a further reduction in the average DC voltage supplied to the heater. This may be particularly beneficial for ultra-low resistance heaters, i.e., heaters with a resistance of about 0.2 to 0.3 ohms, and can compensate for a DC / DC voltage converter with reduced efficiency when providing a significantly reduced output voltage or a significant difference between the input voltage and output voltage of the DC / DC converter.

[0078] Another embodiment of the present disclosure provides a method for controlling an aerosol generator. The aerosol generator may include a DC power supply. The aerosol generator may include a control circuit. The control circuit may be configured to control the supply of power from the DC power supply to a heater for aerosolization of a liquid aerosol-forming substrate. The control circuit may include a DC / DC voltage converter. The DC / DC voltage converter may be configured to receive a DC supply voltage from the DC power supply as input. The DC / DC voltage converter may be configured to output an output voltage for powering the heater. The method may include controlling the DC / DC voltage converter to adjust the output voltage based on a predetermined power profile of the heater.

[0079] Another embodiment of the present disclosure provides a method for controlling an aerosol generator. The aerosol generator comprises a DC power supply and a control circuit configured to control the supply of power from the DC power supply to a heater for aerosolizing a liquid aerosol-forming substrate. The control circuit comprises a DC / DC voltage converter. The DC / DC voltage converter is configured to take a DC supply voltage from the DC power supply as input and output an output voltage for powering the heater. The method includes controlling the DC / DC voltage converter to adjust the output voltage based on a predetermined power profile of the heater.

[0080] Features described in relation to one of the above embodiments may be equally applicable to other embodiments of the present disclosure. [Examples]

[0081] The present invention is defined in the claims. However, a non-exclusive list of non-limiting embodiments is provided below. One or more features of these embodiments may be combined with one or more features of other embodiments, forms, or aspects described herein.

[0082] Example 1: An aerosol generation system comprising a DC power supply for generating a DC supply voltage, and a control circuit for controlling the supply of power from the DC power supply to a heater for aerosolizing a liquid aerosol-forming substrate. Example 2: The aerosol generation system according to Embodiment 1, wherein the control circuit includes a DC / DC voltage converter configured to receive a DC supply voltage as input and output an output voltage for supplying power to a heater. Example 3: The aerosol generating system according to Embodiment 2, comprising a control unit configured to control a DC / DC voltage converter to adjust the output voltage based on a predetermined power profile of the heater. Example 4: The aerosol generating system according to Example 2 or 3, wherein the DC / DC voltage converter is a step-down converter or a buck converter such that the output voltage is less than the DC supply voltage. Example 5: An aerosol generating system according to any one of Examples 2 to 4, wherein a DC / DC voltage converter is disposed between the DC power supply and the heater. Example 6: The aerosol generating system according to any one of Examples 1 to 5, wherein the control circuit further comprises a rectifier or filter for reducing output voltage ripple. Example 7: An aerosol generating system according to any one of Examples 1 to 6, wherein the heater is a resistance heater. Example 8: The aerosol generating system according to Example 7, wherein the resistance heater has an electrical resistance of less than 1 ohm at room temperature. Example 9: The aerosol generating system according to Example 8, wherein the resistance heater has an electrical resistance of less than 0.5 ohms at room temperature. Example 10: The aerosol generating system according to Example 7 or 8, wherein the resistance heater has an electrical resistance of 0.2 to 1 ohm at room temperature. Example 11: The aerosol generation system according to Example 10, wherein the resistance heater has an electrical resistance of 0.2 to 0.5 ohms at room temperature. Example 12: An aerosol generating system according to any one of Examples 1 to 6, wherein the heater comprises an induction heater. Example 13: The aerosol generating system according to Example 12, wherein the induction heater comprises an inductor and a susceptor. Example 14: The aerosol generating system according to Example 13, wherein a susceptor is arranged to be heated by an inductor, and the inductor is configured to generate an alternating magnetic field for heating the susceptor. Example 15: An aerosol generating system according to any one of Examples 12 to 14, wherein the induction heater has an impedance or equivalent resistance of less than 1 ohm at room temperature. Example 16: The aerosol generating system according to Example 15, wherein the induction heater has an impedance or equivalent resistance of less than 0.5 ohms at room temperature. Example 17: An aerosol generating system according to any of Examples 12 to 15, wherein the induction heater has an impedance or equivalent resistance of 0.2 to 1 ohm at room temperature. Example 18: The aerosol generating system according to Example 17, wherein the induction heater has an impedance or equivalent resistance of 0.2 to 0.5 ohms at room temperature. Example 19: An aerosol generating system according to any one of Examples 13 to 18, wherein the control circuit further comprises a DC / AC converter for supplying AC current to an inductor. Example 20: The aerosol generation system according to Embodiment 19, wherein a DC / AC converter is disposed between the DC power supply and the inductor. Example 21: The aerosol generating system according to Embodiment 19 or 20, wherein the control unit is configured to adjust the frequency of the AC current supplied to the inductor and control the power supplied to the inductor based on a predetermined power profile of the induction heater. Example 22: The aerosol generating system according to Embodiment 21, wherein the control unit is configured to increase the frequency of the AC current supplied to the inductor in order to reduce the current in the induction heater, thereby reducing the power supplied to the heater. Example 23: The aerosol generating system according to Examples 1 to 22, wherein a predetermined power profile includes a first period during which a first power value is supplied to the heater. Example 24: The aerosol generating system according to Example 23, wherein the first power value is configured to heat the heater at a predetermined rate. Example 25: The aerosol generating system according to Example 23 or 24, wherein a predetermined power profile includes a second period during which a second power value is supplied to the heater. Example 26: The aerosol generating system according to Example 25, wherein the second power value is different from the first power value. Example 27: The aerosol generating system according to Example 26, wherein the second power value is less than the first power value. Example 28: The aerosol generating system according to any one of Examples 25 to 27, wherein the second power value includes the target power supplied to the heater. Example 29: The aerosol generating system according to any one of Examples 25 to 28, wherein the second power value is configured to maintain the heater at a temperature above the boiling point of the liquid aerosol forming substrate. Example 30: An aerosol generation system according to any one of Examples 25 to 29, wherein a second power value is configured to heat the heater such that the aerosolization rate of the liquid aerosol-forming substrate from the heater is less than or equal to the liquid flow rate of the liquid aerosol-forming substrate in the liquid delivery element of the heater. Example 31: An aerosol generating system according to any of Examples 23 to 30, wherein the first power value is in the range of 6 to 10 watts. Example 32: The aerosol generating system according to Example 31, wherein the first power value is in the range of 7 to 9 watts. Example 33: An aerosol generating system according to any of Examples 25 to 32, wherein the second power value is in the range of 4 to 6 watts. Example 34: An aerosol generating system according to any one of Examples 1 to 33, wherein the control circuit further comprises a memory for storing a predetermined power profile. Example 35: The aerosol generating system according to Example 34, wherein first and second power values ​​are predetermined and stored in memory. Example 36: The aerosol generating system according to Example 35, wherein the first and second power values ​​are stored in a lookup table in memory. Example 37: An aerosol generating system according to any of Examples 1 to 36, wherein the control unit is configured to control a DC / DC voltage converter without using a temperature sensor or resistance measuring sensor. Example 38: An aerosol generating system according to any one of Examples 1 to 37, further comprising a power measuring unit for determining the power supplied to the heater. Example 39: The aerosol generating system according to Embodiment 38, wherein a power measurement unit is connected to a control unit, enabling the control unit to control a DC / DC voltage converter based on one or more signals received from the power measurement unit. Example 40: The aerosol generating system according to Example 38 or 39, wherein a power measuring unit is configured to measure the current through the resistive heater and the voltage across the resistive heater so that a control unit can determine or calculate the power. Example 41: An aerosol generation system according to any one of Examples 38 to 39, wherein the power measurement unit includes a shunt resistor. Example 42: The aerosol generation system according to Example 41, wherein the power measurement unit further comprises an operational amplifier for measuring the voltage across a shunt resistor. Example 43: The aerosol generating system according to Example 42, wherein the heater is equipped with a shunt resistor and the operational amplifier is configured to measure the voltage across the heater. Example 44: A method for controlling an aerosol generator, wherein the aerosol generator comprises a DC power supply and a control circuit for controlling the supply of power from the DC power supply to a heater for aerosolizing a liquid aerosol-forming substrate, the control circuit comprising a DC / DC voltage converter, the DC / DC voltage converter being configured to receive a DC supply voltage as input from the DC power supply and output an output voltage for supplying power to the heater, the method comprising controlling the DC / DC voltage converter to adjust the output voltage based on a predetermined power profile of the heater.

[0083] Here, we will further describe the examples with reference to the figures. [Brief explanation of the drawing]

[0084] [Figure 1] Figure 1 is a temperature-versus-time graph showing the curves of three different amounts of power supplied to the heater. [Figure 2] Figure 2 is a schematic block diagram of a typical heating circuit for an aerosol generation system. [Figure 3] Figures 3A to 3D are graphs showing the maximum instantaneous current draw, maximum instantaneous power, load cycles required to achieve an average power of 5.5 watts, and load cycles required to achieve an average power of 8 watts, respectively, against the heater resistance of a heater directly connected to a power supply. [Figure 4] Figure 4 is a schematic diagram of the inside of an aerosol generation system according to an embodiment of the present disclosure. [Figure 5] Figure 5 is a schematic block diagram of the heating circuit of an aerosol generation system according to an embodiment of the present disclosure. [Figure 6] Figure 6 shows graphs of power versus time and temperature versus time for a given power profile. [Figure 7] Figure 7 is a schematic diagram of an exemplary circuit for implementing the schematic block diagram heating circuit of Figure 5, using an asynchronous DC / DC voltage converter. [Figure 8]Figure 8 is a schematic diagram of another exemplary circuit for implementing the schematic block diagram heating circuit of Figure 5, using a synchronous DC / DC voltage converter. [Figure 9] Figures 9A to 9D are graphs of heater voltage, heater current, load cycle, and battery current, respectively, against the heater resistance of a heater connected to a power supply via a DC / DC voltage converter. [Figure 10] Figure 10 shows graphs of heater current versus time and heater voltage versus time, illustrating the simulation results when power is supplied to the heater. [Figure 11] Figure 11 is a schematic diagram of the interior of an aerosol generation system according to another embodiment of the present disclosure. [Figure 12] Figure 12 is a schematic diagram of a heating circuit for an induction heating aerosol generation system according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0085] It will be understood that at least some of the figures in this application are schematic and have been simplified for clarity. As a result, some features may be omitted, and features are not necessarily shown to scale.

[0086] Referring to Figure 1, a temperature-versus-time graph is shown, which has curves representing three different amounts of power supplied to the heater over a three-second period, characteristic of the average duration of typical smoke extraction. The first curve, A, illustrates the heater's temperature profile when excess power is supplied to the heater. The initial rate of temperature rise in the heater in curve A corresponds to the boiling point T of the liquid aerosol-forming substrate. BP To reach this point more quickly, it is higher than the other curves B and C. Next, the heater temperature rises as the liquid supplied to the heater boils or vaporizes, reaching the boiling point T of the liquid. BPIt stabilizes there. Therefore, the liquid helps regulate the heater temperature and prevents the heater temperature from rising further while the liquid is vaporizing or aerosolizing. However, curve A shows a scenario in which the power supplied to the heater generates an aerosolization rate of the liquid aerosol-forming substrate greater than the liquid flow rate to the heater, such that there is insufficient flow of the liquid aerosol-forming substrate to the heater. This results in a so-called "dry fumes" or "dry heating" condition. Insufficient supply of liquid to the heater leads to overheating of the heater, as indicated by the rapid rise in temperature toward the end of fumes absorption. This can lead to the formation of undesirable byproducts by the heater and result in an undesirable user experience. Furthermore, overheating can cause sustained thermal stress on the heater.

[0087] The second curve B in the graph of Figure 1 illustrates the temperature profile of the heater when an appropriate amount of power is supplied to the heater, and this appropriate amount is smaller than the amount of power supplied to the heater in curve A. The initial rate of temperature rise of the heater in curve B is smaller than in the case of curve A, and the heater in curve B is at the boiling point T of the liquid aerosol-forming substrate. BP It takes a little longer to reach that point. However, the heater temperature will then reach the boiling point T of the liquid for the remainder of the smoke extraction period. BP This indicates stabilization and a sufficient supply of liquid to the heater.

[0088] The third curve C in the graph of Figure 1 illustrates the heater temperature profile when the heater is under-powered. The initial rate of temperature rise in the heater in curve C is smaller than in the cases of curves A and B, and the heater in curve C is at the boiling point T of the liquid aerosol-forming substrate. BP It does not reach the target. As a result, heaters with curve C generate little to no aerosol, leading to an undesirable user experience.

[0089] Figure 2 shows a schematic block diagram of a typical heating circuit 1 for an aerosol generation system. The heating circuit 1 includes a power source 2, such as a battery, connected to a resistance heater 4 equipped with a heating element. The power source 2 is connected to the resistance heater 4 via a switch 6 activated by a control electronic circuit 8 that defines the load cycle required to supply power to the heater. Components not provided solely for heating purposes, such as the user interface and smoke detection, have been omitted for the sake of simplifying the circuit.

[0090] The heating element of heater 4 is made from a conductive material. The electrical resistance of heater 4 is defined as follows: R = ρl / A (1) In the formula, ρ is the electrical resistivity of the material, l is the length of the resistive heating element, and A is its cross-sectional area.

[0091] As mentioned above, increasing the robustness of a resistance heater typically involves increasing the cross-sectional area A of the conductor forming the heating element. However, as can be seen from Equation 1, this increase in cross-sectional area has the adverse effect of reducing the electrical resistance of the heating element. Increasing the resistance by modifying the length l of the conductor is often impossible due to the geometric constraints of the heating region.

[0092] When a defined voltage is supplied, a reduction in electrical resistance, according to Ohm's law, is accompanied by an increase in current flow. I = V / R (2) In the equation, I is the current flowing through the heater of resistor R from a power source having voltage V. The generated power P is: P=VI=I 2 R=V 2 / R (3) That is the case.

[0093] At a constant battery voltage, according to Equation 3, lower resistance generates higher instantaneous power. The desired average power P is lower than the instantaneous power P. avgTo achieve this, it is known to use pulse width modulation (PWM) to regulate the voltage supplied to the heating element. This typically consists of switching the heating element on and off at a frequency in the range of several hundred Hertz to kilohertz.

[0094] Using PWM, the heater is on for the duration of t on and then off for the duration of t off During this time, the current I flows through the heater supplied by the voltage V. The durations of t on and t off are summed up to one complete cycle, the time of t cycle The duty cycle (DC) is obtained by dividing t on by t cycle During the "on" state, the instantaneous power P is achieved by multiplying V by I. The instantaneous power P changes over time as the voltage V decreases when discharging the battery during the use of the vaping device, and I decreases as the heater resistance R increases with temperature during smoking. The desired average power P avg of the heating element is calculated by adjusting the duty cycle DC to correct for the variations in P and is kept constant. The desired average power P avg is always below P. P avg =P * DC = V * I * t on / t cycle (4)

[0095] Figures 3A to 3D are graphs of the theoretical maximum instantaneous current draw, maximum instantaneous power, load cycles to achieve an average power of 5.5 watts, and load cycles to achieve an average power of 8 watts, respectively, for a resistive heater with heater resistance directly connected to a power source such as a lithium-ion battery. The resistive heater has a resistance of 0.3 ohms at nominal temperature or room temperature (referred to herein as the cold heater) and an increased resistance of 0.45 ohms at the boiling point of the liquid being vaporized (referred to herein as the hot heater). The battery voltage ranges from 3.7 volts to 2.5 volts when fully charged, which is the lower limit setting at which the aerosol generating system can be programmed to stop operating due to battery depletion.

[0096] Figure 3A shows the "on" time t. on The instantaneous current I supplied to the heater is provided within. The current I ranges from 5.6 amps for the hot heater and a depleted battery to 12.3 amps for the cold heater supplied by a fully charged battery. The shaded areas in the graphs of Figures 3A to 3D represent the operating zone of the resistance heater.

[0097] Figure 3B shows the maximum instantaneous power P, i.e., V, that can be delivered to the heater. * I (see Equation 3) is shown. The maximum instantaneous power P ranges from 13.9 watts for the hot heater and depleted battery to 45.6 watts for the cold heater powered by a fully charged battery. Both of these P values ​​are sufficient to supply the heater with an expected power of 5.5 watts to 8 watts.

[0098] Figure 3C shows the average power P of 5.5 watts, taking into account the instantaneous power P results in Figure 3B. avg It provides the load cycles necessary to achieve this. These load cycles range from 12.1% for a cold heater powered by a fully charged battery to 39.6% for a hot heater and a depleted battery.

[0099] Figure 3D shows the average power P of 8 watts, taking into account the instantaneous power P results in Figure 3B. avg It provides the load cycles necessary to achieve this. These load cycles range from 17.5% for cold heaters powered by fully charged batteries to 57.6% for hot heaters and depleted batteries. Therefore, even with a maximum heater "on" time of 57.6% during the cycle, more than 40% of the power is consumed, resulting in a higher average heater power P avg It is still available to reach the target, potentially increasing aerosol delivery, or it remains unused.

[0100] Figures 3A to 3D clearly show that operating a heater with a heating element having low electrical resistance by directly connecting the heater to a battery has several drawbacks. Firstly, this can draw high instantaneous current from the battery and flow through the heater. This can be harmful to the battery, as it may pose a risk of overheating and, in extreme cases, potentially causing the battery to explode. Furthermore, high instantaneous current can reduce the efficiency of the heater, especially if the heater resistance is close to the resistance of the electrical track connected to the heater. Secondly, applying small load cycles, i.e., briefly turning the power supply "on" during a PWM cycle to compensate for the high instantaneous power generated while the heater is "on," can make it difficult to control in order to ensure a stable average power and may cause switching losses that result in lower efficiency when operating the heater. The aerosol generation system of this disclosure has been developed with these drawbacks in mind.

[0101] Figure 4 shows a schematic diagram of the interior of an aerosol generating system 100 according to an embodiment of the present disclosure. The aerosol generating system 100 comprises two main components, a cartridge 102 and a main body or aerosol generating device 104. A connection end 106 of the cartridge 102 is detachably connected to a corresponding connection end 108 of the aerosol generating device 104. The connection end 106 of the cartridge 102 and the connection end 108 of the aerosol generating device 104 each have electrical contacts or connections (not shown) arranged to cooperate to provide an electrical connection between the cartridge 102 and the aerosol generating device 104. The aerosol generating device 104 comprises a power source in the form of a battery 110, which in this example is a rechargeable lithium-ion battery, and a control circuit 112. The aerosol generating system 100 is portable and also has a size comparable to a conventional cigar or cigarette. A mouthpiece 114 is located at the end of the cartridge 102 opposite to the connection end 106.

[0102] The cartridge 102 comprises a resistance heater 118 and a housing 116 that houses a liquid storage compartment or portion having a first storage portion 120 and a second storage portion 122. The liquid aerosol-forming substrate is held within the liquid storage compartment. Although not shown in Figure 4, the first storage portion 120 of the liquid storage compartment is connected to the second storage portion 122 of the liquid storage compartment so that the liquid in the first storage portion 120 can move to the second storage portion 122. The heater 118 receives liquid from the second storage portion 122 of the liquid storage compartment. The heater 118 comprises a ceramic liquid delivery element and a heating element (not shown) disposed on the side of the liquid delivery element opposite to the second storage portion 122 of the liquid storage compartment. During use, the liquid delivery element transports the liquid aerosol-forming substrate to the heating element. At least a portion of the liquid delivery element is in contact with, or extends into, the second storage portion 122 of the liquid storage compartment and is in contact with the liquid aerosol-forming substrate within it.

[0103] The airflow passage 124 passes through the heating element of the heater 118 from the air intake 126 formed on the side of the housing 116, and then extends through the cartridge 102 from the heater 118 to the mouthpiece opening 128 formed in the housing 116 at the end of the cartridge 102 opposite the connection end 106.

[0104] The components of cartridge 102 are arranged such that the first storage portion 120 of the liquid storage compartment is located between the heater 118 and the mouthpiece opening 128, and the second storage portion 122 of the liquid storage compartment is located on the opposite side of the heater 118 from the mouthpiece opening 128. In other words, the heater 118 is placed between the two portions 120 and 122 of the liquid storage compartment and receives liquid from the second storage portion 122. The first storage portion 120 of the liquid storage compartment is closer to the mouthpiece opening 128 than the second storage portion 122 of the liquid storage compartment. The airflow passage 124 passes through the heating element of the heater 118 and extends between the first storage portion 120 and the second storage portion 122 of the liquid storage compartment.

[0105] The aerosol generating system 100 is configured to allow the user to inhale or draw out an aerosol into their mouth through the mouthpiece opening 128 by inhaling or drawing out through the mouthpiece 114 of the cartridge 102. When in operation, as the user inhales through the mouthpiece 114, air is drawn out from the air intake 126 through the airflow passage 124, past the heater 118, and into the mouthpiece opening 128. The control circuit 112 controls the supply of power from the battery 110 to the cartridge 102 when the system is activated. This consequently controls the amount and characteristics of the vapor produced by the heater 118. The control circuit 112 may include an airflow sensor or inhalation detector (not shown), and the control circuit 112 may also supply power to the heater 118 when the user's inhalation is detected by the airflow sensor. This type of control arrangement is well established in aerosol generating systems such as inhalers and e-cigarettes. When the user inhales vapor from the mouthpiece opening 128 of the cartridge 102, the heater 118 is activated, generating vapor that is carried along with the airflow passing through the airflow passage 124. The vapor cools within the airflow in the passage 124 to form an aerosol, which is then drawn into the user's mouth through the mouthpiece opening 128.

[0106] During operation, the mouthpiece opening 128 is typically the highest point of the system. The construction of the cartridge 102, and in particular the placement of the heater 118 between the first storage section 120 and the second storage section 122 of the liquid storage compartment, is advantageous because it ensures that gravity is utilized to deliver the liquid substrate to the heater even when the liquid storage compartment is beginning to empty, and prevents an oversupply of liquid to the heater 118, which could still lead to liquid leakage into the airflow passage 124.

[0107] Figure 5 shows a schematic block diagram of the heating circuit 200 of an aerosol generation system according to an embodiment of the present disclosure. Some components that are not provided solely for heating purposes, such as the user interface and smoke detection, have been omitted from the heating circuit in Figure 5 for simplification. The heating circuit 200 in Figure 5 comprises a DC power supply 202, such as a battery, connected to a heater 204, which can be either a resistance heater or an induction heater. The heating circuit 200 further comprises a control circuit for controlling the power supply from the DC power supply to the heater 204 for aerosolization of a liquid aerosol-forming substrate.

[0108] In the heating circuit 200 of Figure 5, the DC power supply 202 is not directly connected to the heater 204. Instead, the control circuit includes a DC / DC voltage converter 206 connected between the DC power supply 202 and the heater 204. The DC / DC voltage converter 206 is a buck converter, which takes a DC supply voltage from the DC power supply 202 as input and outputs a reduced output voltage to the heater 204. The DC / DC voltage converter 206 includes a switch (not shown) that can be activated by a PWM modulated voltage signal provided by the control unit 208. It is understood that the PWM modulated voltage signal here is used to control the output voltage supplied by the DC / DC voltage converter and is different from the PWM voltage that can be applied directly to the heater when the power is controlled only by PWM modulation. The control unit 210 can define load cycles for powering the heater. Furthermore, the control unit 210 is configured to control the DC / DC voltage converter 206 to adjust the output voltage based on a predetermined power profile of the heater 204. The heating circuit 200 further includes a power measurement unit 210 for determining the power supplied to the heater 204. The power measurement unit 210 is connected between the DC / DC voltage converter 206 and the heater 204. The power measurement unit 210 is also connected to a control unit 208, which enables the control unit 208 to control the DC / DC voltage converter 206 based on one or more signals received from the power measurement unit 210.

[0109] Figure 6 provides a first graph of power P versus time t (see upper graph) showing that a given power profile X is supplied to the heater during a typical smoke extraction duration. Figure 6 also provides a second graph showing the corresponding temperature T of the heater during the smoke extraction duration. In other words, the lower graph shows how the heater temperature T changes as a result of applying the given power profile X in the upper graph.

[0110] Referring to the upper graph in Figure 6, a given power profile X includes a first period Δt1 between time t1 and time t1, during which a first power value P1 is supplied to the heater. The given power profile X further includes a second period Δt2 between time t1 and t2, during which a second power value P2 is supplied to the heater. The first power value P1 is greater than the second power value P2, and is configured to heat the heater at a predetermined rate. This is illustrated by the temperature profile Y in the lower graph, which shows that the heater temperature rises from the ambient temperature at the start of smoke extraction, i.e., when time is equal to zero. The predetermined rate can be any suitable predetermined rate, but generally, the purpose of the first power value P1 is to bring the heater to the boiling point T of the liquid aerosol-forming substrate in order to initiate aerosolization of the liquid aerosol-forming substrate. BP The key is to heat it as quickly as possible.

[0111] boiling point T BPWhen time t1 is reached, a second power value P2 is supplied to the heater, which is smaller than the first power value P1. The decrease in power from P1 to P2 is provided by a control unit 208 that controls the DC / DC voltage converter 206 to reduce the voltage of the DC power supply 202 supplied to the heater 204. The switch from the first power value P1 to the second power value P2 is performed without the use of a temperature sensor or temperature data. Instead, the switch from the first power value P1 to the second power value P2 is based solely on power delivery, such as a feedback voltage or feedback current from a power management unit, or a predetermined value for time t1 stored in memory. The purpose of the second power value P2 is to raise the heater to the boiling point T of the liquid aerosol-forming substrate. BP This means maintaining a temperature that is substantially equal to or close to that of the target temperature.

[0112] The second power value P2 is also configured to heat the heater such that the aerosolization rate of the liquid aerosol-forming substrate from the heater is less than or equal to the liquid flow rate of the liquid aerosol-forming substrate in the liquid delivery element of the heater. In an aerosol generation system, the heater typically comprises a heating element and a liquid delivery element for transporting the liquid aerosol-forming substrate to the heating element. Therefore, the second power value P2 is configured to heat the heater such that the aerosolization rate of the liquid aerosol-forming substrate does not exceed the liquid flow rate of the liquid aerosol-forming substrate to the heater. This helps to avoid dry fume absorption or dry heating conditions, which can result in an undesirable user experience. Furthermore, as mentioned above, the presence of liquid is important as it limits the boiling point T of the liquid aerosol-forming substrate. BP In addition to helping maintain the heater temperature and reducing power consumption, the boiling point T of the liquid aerosol-forming substrate BP This helps to avoid further increases in the heater temperature beyond a certain point. Therefore, the liquid flow rate of the liquid aerosol-forming substrate helps to regulate the heater temperature.

[0113] For specific heaters, liquid aerosol-forming substrates, and liquid flow rates, a first power value P1 and a second power value P2 can be predetermined and stored in memory (not shown), such as a lookup table, which forms part of the control unit 208. The respective values ​​of P1 and P2 can then be supplied to the heater at the appropriate time during the heating cycle or fume extraction. Monitoring the heater temperature or following a temperature profile is not required. Therefore, temperature sensors are not needed, which helps simplify the manufacturing and operation of the aerosol generation system.

[0114] As can be seen in Figure 6, the first power value P1 and the second power value P2 supplied to the heater 204 are substantially constant over the period in which they are applied. However, it will be understood that there may be some variation in the first power value P1 and the second power value P2, for example, in response to signals received from the power management unit 210, and to account for changes in the resistance of the heater 204 caused by temperature changes in the heater 204 itself, different ambient temperatures, and manufacturing tolerances of the heater 204 itself. The second power value P2 is supplied to the heater 204 until time t2 when the user's smoke extraction ends.

[0115] Figure 7 is a schematic diagram of an exemplary heating circuit 201 for implementing the schematic block diagram heating circuit of Figure 5. The heating circuit 201 in Figure 7 comprises the same main components as the heating circuit in Figure 5, namely, a DC power supply 202, a heater 204, a DC / DC voltage converter 206, a control unit 208, and a power management unit 210 connected in the same manner as in Figure 5. Similar reference numerals are used in Figure 7 to indicate similar features to those in Figure 5. The DC / DC voltage converter 206 is indicated by a dashed box enclosing the main components of the DC / DC voltage converter 206. The DC / DC voltage converter 206 in Figure 7 is asynchronous and comprises a transistor 212 and a diode D. The transistor 212 constitutes the first switching element, and the diode D constitutes the second switching element. In the exemplary circuit 201 in Figure 7, the transistor 212 is an N-channel metal oxide semiconductor field-effect transistor (MOSFET), which is advantageous because it has a faster switching speed and lower "on" resistance than other types of transistors, although other types of transistors can be used.

[0116] MOSFET 212 is connected to input 214 of DC / DC voltage converter 206 and receives a DC supply voltage from DC power supply 202. MOSFET 212 acts as a switch to allow current to flow from DC power supply 202 to heater 204. MOSFET is also connected to control unit 208 via gate driver 216, which is configured to provide a switching signal to MOSFET 212 to operate it. The switching signal is a PWM signal with a constant load cycle. Diode D is connected in parallel with the heater 204 load between MOSFET 212 and electrical ground. Inductor L is connected in series between MOSFET 212 and output 218 of DC / DC voltage converter 206. Output 218 of DC / DC voltage converter 206 is connected to heater 204. DC / DC voltage converter 206 further includes capacitor C connected between output 218 of DC / DC voltage converter 206 and electrical ground, i.e., in parallel with heater 204. The inductor L and capacitor C act as a low-pass LC filter, helping to filter pulses from the switching signal and provide a smoother DC output voltage from the DC / DC voltage converter.

[0117] When the switching signal is "on," MOSFET 212 is activated, and current flows from the DC power supply 202 through MOSFET 212 to heater 204. When the switching signal is "off," MOSFET 212 is stopped, and current continues to flow through heater 204 through diode D until MOSFET 212 is restarted during the next PWM cycle, due to the magnetic energy stored in inductor L, and then returns, and this process repeats itself. Thus, the DC / DC voltage converter 206 helps to provide a continuous but reduced voltage at its output 218 connected to heater 204. The output voltage at output 218 of the DC / DC voltage converter 206 is proportional to the DC supply voltage multiplied by the load cycle percentage of the switching signal.

[0118] Although the DC / DC voltage converter 206 in circuit 201 in Figure 1 is shown as being formed from individual components, it will be understood that the DC / DC voltage converter 206 can also be formed as an integrated circuit.

[0119] In the embodiment shown in Figure 7, the control unit 208 includes a microcontroller having a memory for storying a predetermined power profile, including the power values ​​supplied to the heater 204. The control unit 208 further includes at least two analog-to-digital converters (ADCs) having inputs for receiving current and voltage signals from the power measurement unit 210 and converting them into digital values ​​for processing by the control unit 208.

[0120] The power measurement unit 210 of the heating circuit 201 in Figure 7 is shown by another dashed box enclosing the main components of the power measurement unit 210. The function of the power measurement unit 210 is to measure the power delivered to the heater 204. The power measurement unit is configured to measure the voltage across the heater 204 and the current flowing through the heater 204. The current measurement section of the power measurement unit 210 is connected to a shunt resistor R between the output 218 of the DC / DC voltage converter 206 and the heater 204. shunt It is equipped with a shunt resistor R. shunt This has a known value, and preferably is a shunt resistor R shunt The resistor has a small resistance value, such as 2 milliohms, so that the voltage drop across its terminals is not significant and does not adversely affect the power delivered to the heater 204. The current measuring section of the power measuring unit 210 also has a shunt resistor. shunt The operational amplifier 220 has inputs connected to both sides of and an output connected to the ADC input of the control unit 208. The operational amplifier 220 is connected to the shunt resistor R shunt It provides an amplified voltage signal proportional to the voltage across its terminals. (Shunter resistor R) shunt The current passing through is equal to the current passing through heater 204. (Shunter resistor R) shunt The current passing through the shunt resistor R, and therefore the current passing through heater 204, shuntThe voltage across both ends and the shunt resistor R shunt This can be determined by applying Ohm's law (see equation 2 above) to the known resistance.

[0121] Naturally, the components of the current measuring section of the power measuring unit 210 can be implemented within an integrated circuit.

[0122] The voltage measurement unit of the power management unit 210 measures the voltage of the heater 204 at a point in the circuit, i.e., the shunt resistor R in circuit 201 in Figure 7. shunt The voltage at the point between the heater 204 and the power supply unit 210 is measured directly. The voltage measurement is then supplied to the control unit 208 by a direct connection 224 to the ADC input of the control unit 208. Direct voltage measurement is possible when the voltage supplied to the heater 204 is significantly lower than the voltage supplied to the control unit 208, which is the case when supplying a low-resistance heater as used in this disclosure. This is beneficial because it requires fewer electronic components and reduces measurement inaccuracies due to component tolerances. Alternatively, the voltage of the heater 204 may be measured through a voltage divider. Naturally, the power management unit 210 can measure the power supplied to the heater 204 using relatively simple components and by measuring the voltage and current supplied to the heater 204. This avoids the need for more complex and expensive components such as temperature sensors, and the difficulties of using such components, such as integrating them into the heating circuit and calibration.

[0123] Once the current flowing through heater 204 and the voltage across heater 204 are determined, the power supplied to heater 204 can be determined by the control unit 208 using equation 3 above. Preferably, the current and voltage measurements are acquired simultaneously by separate ADC inputs of the control unit 208. This helps reduce noise and achieve more accurate measurements compared to what may occur if the current and voltage measurements are performed alternately. Based on the determined power, the control unit 208 calculates the load cycles required to reach the desired power value delivered to heater 204. The control unit 208 has at least one output for controlling transistor 212 of DC / DC voltage converter 206.

[0124] Figure 8 is a schematic diagram of another exemplary heating circuit 203 for implementing the schematic block diagram heating circuit of Figure 5. The heating circuit 203 in Figure 8 is identical to the heating circuit 201 in Figure 7, except that the DC / DC voltage converter 207 is a synchronous DC / DC voltage converter and the diode D in Figure 7 is replaced by a second transistor 226. In the circuit 203 in Figure 7, the first transistor 212 constitutes the first switching element and the second transistor 226 constitutes the second switching element. Both the first transistor 212 and the second transistor 226 in circuit 203 are N-channel MOSFETs and are connected to the control unit 208 via their own gate drivers 216.

[0125] The control unit 208 is configured to provide a first switching signal to the first MOSFET 212 to operate the first MOSFET 212, and a second switching signal to the second MOSFET 226 to operate the second MOSFET 226. The first switching signal is a PWM signal with a specific load cycle. The second switching signal is the inverse or reverse form of the first switching signal, so that when the first switching element is activated, the second switching element is stopped, and when the second switching element is activated, the first switching element is stopped. Advantageously, this avoids a short circuit between the DC power supply and electrical ground.

[0126] When the first switching signal is "on," the first MOSFET 212 is activated and the second MOSFET 226 is deactivated so that current flows from the DC power supply 202 through the first MOSFET 212 to the heater 204. When the first switching signal is "off," the first MOSFET 212 is deactivated and the second MOSFET 226 is activated, and current continues to flow through the heater 204 and back through the second MOSFET 226 due to the magnetic energy stored in the inductor L until the first MOSFET 212 is restarted during the next PWM cycle, and this process repeats itself. Thus, the DC / DC voltage converter 207 helps to provide a continuous but reduced voltage at the output 218 of the DC / DC voltage converter 207 connected to the heater 204. The output voltage at the output 218 of the DC / DC voltage converter 207 is proportional to the DC supply voltage multiplied by the load cycle percentage of the first switching signal.

[0127] Although the DC / DC voltage converter 207 in circuit 203 in Figure 1 is shown as being formed from individual components, it will be understood that the DC / DC voltage converter 207 can also be formed as an integrated circuit.

[0128] The heater 204 in circuits 201 and 203 in Figures 7 and 9 can be either a resistance heater or an induction heater. No modification to either circuit 201 or circuit 203 is required to implement a resistance heater. However, an induction heater requires additional components, and a suitable circuit for an induction heater is described below with respect to Figure 12.

[0129] Figures 9A–9D are graphs of the logical heater voltage, heater current, load cycle, and battery current, respectively, against the heater resistance of a heater connected to a power supply via a DC / DC voltage converter such as the buck converter illustrated in Figures 7 and 8. The heater has the same characteristics as the heater used to produce the data in Figures 3A–3D, namely having a resistance of 0.3 ohms at nominal temperature or room temperature (referred to herein as the cold heater) and an increased resistance of 0.45 ohms at the boiling point of the liquid being vaporized (referred to herein as the hot heater). The inductor L and capacitor C of the DC / DC voltage converter were set to 1 microhenry and 8.3 microfarads, respectively. These values ​​showed a good stabilization time of less than 50 μs and an acceptable amount of ripple in the voltage supplied to the heater. It was shown that the voltage supplied to the heater was independent of the DC supply voltage provided by the DC power supply, in this case the lithium-ion battery.

[0130] Referring to Figure 9A, to achieve 5.5 watts of power, the voltage supplied to the heater changed from 1.28 volts for the cold heater to 1.57 volts for the hot heater. When targeting 8 watts of power, the supply voltage increased to 1.55 volts to 1.90 volts. These voltage values ​​are significantly lower than the DC supply voltage from a DC power source.

[0131] As shown in Figure 9B, the current flowing through the heater decreased with increasing heater resistance. To achieve 5.5 watts of power, the current flow from 4.28 amperes in the cold heater to 3.49 amperes in the hot heater was simulated. To achieve 8 watts of power, the current flow from 5.16 amperes in the cold heater to 4.21 amperes in the hot heater was simulated.

[0132] Referring to Figure 9C, the load cycles applied to the DC / DC voltage converter depended on the battery's DC supply voltage and target power. With a depleted battery, targeting 8 watts to be dissipated in the hot heater, the lowest load cycle rate was 17.7%. With a fully charged battery supplying 5.5 watts to the cold heater, the highest load cycle rate was 52.7%.

[0133] Referring to Figure 9D, the highest average current drawn from the energy source was 3.7 amperes, which remains within the safe operating limits of the lithium-ion battery to avoid overheating. This occurred with a cold heater targeting 8 watts with a depleted battery. Of all the simulations performed, the maximum peak current from the battery was 5.7 amperes (not shown in Figures 9A–9D). This is significantly lower than the 12.3 amperes that occur when the DC power supply is directly connected to the heater (see Figure 3A).

[0134] Figures 9A to 9D clearly show that there are many advantages to operating a heater with a low electrical resistance heating element by connecting a DC power supply via a voltage-reducing DC / DC voltage converter. Firstly, it results in a lower instantaneous current drawn from the DC power supply, which helps reduce heating of the DC power supply. Secondly, it provides DC current to the heater, which has improved characteristics and advantages in itself, i.e., it helps reduce current peaks with potentially high amplitude, helps reduce heat dissipation in the lead track to the heater, and may also help extend the heater's lifespan by reducing thermal stress and electromigration effects.

[0135] Figure 10 is a theoretical heater current vs. time and heater voltage vs. time graph showing the simulated voltage and current supplied to the heater via a voltage reduction DC / DC voltage converter as illustrated in Figures 7 and 8. The heater has a resistance of 0.3 ohms at room temperature and is targeted at 8 watts. The amplitudes of the ripple voltage and current are 17 millivolts and 55 milliamperes, respectively. This results in a ripple power of 173 milliwatts. As mentioned above, for the simulations in Figures 9A–9D, the inductor L and capacitor C were set to 1 microhenry and 8.3 microfarads, respectively. The simulations illustrated in Figure 10 further show that increasing the inductor or capacitor value, or both, reduces ripple at the expense of longer stabilization times. Ripple in voltage and current signals can also be reduced by including rectifiers or filters. This is particularly useful when supplying voltage and current signals to the control units in Figures 7 and 8 to determine power measurements, and helps reduce signal fluctuations and noise.

[0136] Figure 11 is a schematic diagram of the interior of an induction heating aerosol generating system 300 according to another embodiment of the present disclosure. The aerosol generating system 300 comprises a cartridge 310 and an aerosol generator 360. The cartridge 310 is configured to be received by the aerosol generator 360. Figure 11 shows that the cartridge 310 is received within and attached to the aerosol generator 360. The aerosol generating system 300 is portable and has a size comparable to a conventional cigar or cigarette. The cartridge 310 has a mouth end and a connection end opposite to the mouth end. The connection end is configured to connect the cartridge 310 to the aerosol generator 360.

[0137] The cartridge 310 comprises an outer housing 336 formed from a moldable plastic material such as polypropylene. The outer housing 336 defines an oral end opening 338 at the oral end of the cartridge 310. The outer width of the outer housing 336 is greater at the oral end of the cartridge 310 than at the connection end. This forms a shoulder 337 between the oral end and the connection end. This arrangement allows the shoulder 337 to position the cartridge 310 correctly within the device so that the connection end of the cartridge 310 is received within the cavity 364 of the aerosol generator 360. This also allows the oral end of the cartridge 310 to remain outside the aerosol generator 360 and to conform to the external shape of the aerosol generator 360.

[0138] The cartridge 310 further comprises a susceptor assembly 312 mounted on a susceptor holder 314. The susceptor assembly 312 is described in more detail below. The susceptor holder 314 comprises a tubular body formed from a moldable plastic material such as polypropylene. The tubular body of the susceptor holder 314 has side walls defining an internal passage 326 having an open end and a central longitudinal axis. A pair of openings 328 extend through the side walls on opposing sides of the tubular susceptor holder 314. The openings 328 are centrally located along the length of the susceptor holder 314. The susceptor holder 314 further comprises a base 330 that partially closes one end of the internal passage 326. The base 330 has a plurality of air intakes 332 that allow air to be drawn into the internal passage 326 through the partially closed end.

[0139] The cartridge 310 further comprises a liquid storage section or liquid reservoir 344 for storing the liquid aerosol forming substrate 342. The liquid reservoir 344 comprises an annular space defined by the outer housing 336 and an internal passage 348 extending between the mouth-side air outlet 338 and the open end of the internal passage 326 of the susceptor holder 314.

[0140] The cartridge 310 further comprises two channels 345 defined between the inner surface of the outer housing 336 and the outer surface of the susceptor holder 314. The two channels 345 extend from the liquid reservoir 344 to the connection end of the cartridge 310 at the mouth end of the cartridge 310.

[0141] The susceptor assembly 312 and susceptor holder 314 are positioned toward the connection end of the cartridge 310. The susceptor assembly 312 is planar and thin, with a thickness dimension substantially smaller than its length and width dimensions. The susceptor assembly 312 is molded into a rectangular shape. The susceptor assembly 312 comprises a susceptor comprising a first susceptor element 316 and a second susceptor element (not shown) opposite the first susceptor element 316. The first susceptor element 316 and the second susceptor element act as heating elements for heating the liquid aerosol-forming substrate, as will be further described below. The susceptor assembly 12 also comprises a liquid delivery element 320 for transporting the liquid aerosol-forming substrate 342 from the liquid reservoir 344 to the susceptor. The liquid delivery element 320 contains wicking material and is sandwiched between the first susceptor element 316 and the second susceptor element.

[0142] The widths of the first susceptor element 316 and the second susceptor element are smaller than the width of the liquid delivery element 320. Therefore, the liquid delivery element 320 has an outer exposed portion that protrudes into the two channels 345 through an opening 328 in the side wall of the susceptor holder 314. The first susceptor element 316 and the second susceptor element are substantially identical and include a sintered mesh formed from stainless steel filaments suitable for heating by an alternating magnetic field.

[0143] The susceptor assembly 312 is partially disposed inside the internal passage 326 of the tubular susceptor holder 314 and extends in a plane parallel to the central longitudinal axis of the susceptor holder 314. The first susceptor element 316 and the second susceptor element are fully disposed within the internal passage 326 of the susceptor holder 314.

[0144] The aerosol generator 360 comprises a substantially cylindrical housing 362 having a connecting end and a distal end on the opposite side of the connecting end. A cavity 364 for receiving the connecting end of the cartridge 310 is located at the connecting end of the device 360. An air intake 365 is provided through the outer housing 362 at the base of the cavity 364 to allow ambient air to be drawn into the cavity 364 at its base. A smoke extraction detector in the form of an airflow sensor 363 is disposed within the base of the cavity 364 to detect when air is being drawn into the cavity 64.

[0145] The aerosol generator 360 includes an induction heating arrangement housed within an outer housing 362 of the device. The induction heating arrangement includes an inductor coil 390, a control circuit 370, and a DC power supply 372. The DC power supply 372 comprises a rechargeable lithium-ion battery, which is rechargeable via an electrical connector (not shown) at the distal end of the device 360. The control circuit 370 is connected to the power supply 372 and the inductor coil 390 so that the control circuit 370 controls the power supply to the inductor coil 390. The control circuit 370 is configured to supply alternating current to the inductor coil 390. The control circuit 370 is also connected to an airflow sensor 363.

[0146] As shown in Figure 11, the inductor coil 390 is positioned around the susceptor assembly 312 when the cartridge 310 is received within the cavity 364. The inductor coil 390 has a size and shape that matches the size and shape of the heating area of ​​the susceptor element. The inductor coil 390 is made of copper wire with a circular cross-section and is arranged on a coil-wound element (not shown). The inductor coil 390 is a helical coil and has a circular cross-section when viewed parallel to the longitudinal axis of the aerosol generator 360.

[0147] The inductor coil 390 is configured such that when an alternating current is supplied to the inductor coil, the inductor coil generates an alternating magnetic field within the region of the susceptor assembly 312 when the cartridge 310 is received in the cavity 364. The induction heating arrangement further includes a flux centrifuge element 391. The flux centrifuge element 391 has a larger radius than the inductor coil 390 and therefore partially surrounds the inductor coil 390. The flux centrifuge element 391 is configured to reduce stray power losses from the generated magnetic field.

[0148] During operation, when the user inhales smoke at the mouth-end air outlet 338 of the cartridge 310, ambient air is drawn into the base of the cavity 364 through the system's air intake 365 and drawn into the cartridge 310 through the air intake 332 of the base 330 of the cartridge 310. The ambient air flows through the cartridge 310, from the base 330 to the mouth-end air outlet 338, through the air passage 326, over the susceptor assembly 312, particularly over and across the first susceptor element 316 and the second susceptor element.

[0149] The airflow sensor 363 detects the air drawn into the system when the user inhales smoke through the mouth-side air outlet 338. The airflow sensor 363 sends a signal to the control circuit 370 to start the system. When the system is started, the control circuit 370 controls the supply of power from the power supply 372 to the inductor coil 390.

[0150] When the system is activated, an alternating current is established in the inductor coil 390, which generates an alternating magnetic field in the cavity 364 that penetrates the susceptor assembly 312, heating the first susceptor element 316 and the second susceptor element. The liquid aerosol-forming substrate 342 in the two channels 345 is drawn into the susceptor assembly 312 through the liquid delivery element 320 to the first susceptor element 316 and the second susceptor element. The liquid aerosol-forming substrate 342 is heated in the first susceptor element 316 and the second susceptor element, and volatile compounds from the heated liquid aerosol-forming substrate are released into the air passage of the cartridge 310, where they cool and form an aerosol. The aerosol is carried by the air drawn in through the air passage 326 of the cartridge 310 and is drawn out of the cartridge 310 at the mouth-side air outlet 338 for inhalation by the user.

[0151] Figure 12 is a schematic diagram of a heating circuit 400 that forms part of the control circuit 370 of the induction heating aerosol generation system 300 of Figure 11. The circuit 400 in Figure 12 is used to drive the induction coil 390 of the aerosol generator 360 of Figure 11, and to determine one or more electrical parameters of the susceptor shown in cartridge 10 of Figure 11, i.e., the first susceptor element 316 and the second susceptor element. The circuit 400 has an input voltage Vin received at point X in Figure 12. The circuit 400 may be connected to a DC / DC voltage converter (not shown) so that it can receive a reduced input voltage and control the power supplied to the induction coil 390. Thus, point X of the circuit 400 in Figure 12 may be connected to the output 218 of DC / DC voltage converters 206 and 207 shown in Figures 7 and 8, respectively.

[0152] Circuit 400 includes a transistor switch Q1 and a first inductor L1, which function as a drive circuit for driving the induction coil 390 and the DC / AC voltage converter. The transistor switch Q1 is equipped with a MOSFET, and the first inductor L1 is equipped with a radio frequency choke, which helps reduce radio frequencies that may be present in input X entering the circuit. The gate G of the transistor switch Q1 receives a switching signal generated by a control circuit, for example, another component (not shown) of the control circuit 208 in Figures 7 and 8. The switching signal is a square wave with substantially 50% load cycles and is configured to turn the transistor switch Q1 on and off. Note that the switching signal supplied to transistor Q1 is different from the switching signals used to control the DC / DC voltage converters 206 and 207 in Figures 7 and 8, respectively.

[0153] Circuit 400 further comprises a first capacitor C1 connected in series with a second inductor L2, which corresponds to the induction coil 390 of the aerosol generator 360 in Figure 11. The second capacitor C2 is connected between the drain D of the transistor switch Q1 and electrical ground and acts as a shunt capacitor. The first capacitor C1, the second inductor L2, and the second capacitor C2 define a DC / AC voltage converter for converting the switching signal passed to the transistor switch Q1 into an AC voltage across an equivalent resistor R4. The equivalent resistor R4 is equivalent to the ohm resistance of the second inductor L2 connected in series with the apparent ohm resistances of the first susceptor element 316 and the second susceptor element of the cartridge 10 in Figure 11. It will be understood that the equivalent resistor R4 can be considered as the impedance taking into account the combined resistance and reactance of the induction coil L2 and the susceptor elements. The resistance or impedance R4 typically has a low value, i.e., less than 1 ohm. In Figure 12, resistor R4 is shown with a dashed outline to indicate that it is not an actual resistor in the circuit, but rather the equivalent resistance of the second inductor L2 and the first susceptor element 316 and the second susceptor element.

[0154] Together, the first inductor L1, the transistor switch Q1, the first capacitor C1, the second inductor L2, and the second capacitor C2 form a Class E power amplifier. The general operating principle of Class E power amplifiers is known and is described in detail in the paper "Class-E RF Power Amplifiers" by Nathan O. Sokal, published in the January / February 2001 edition, pages 9-20, of the bimonthly journal QEX of the American Radio Relay League (ARRL), Newington, CT, USA, and therefore will not be discussed further herein.

[0155] It has been found that powering the second inductor L2 using a Class E amplifier is highly efficient. This is because, due to the circuit configuration, while there is a voltage across the transistor switch Q1, no current flows through the transistor switch Q1 at the same time. As a result, virtually no energy dissipates in the transistor switch Q1, and instead, virtually all power is supplied to the load equivalent resistance R4. Furthermore, the first capacitor C1 and the second inductor L2 form a series resonant circuit tuned to the switching frequency of the switching signal. The first capacitor C1 and the second inductor L2 act as a bandpass filter, allowing the AC voltage signal to be transmitted to the load equivalent resistance R4 only at the desired operating frequency of the second inductor L2. This means that power is transmitted to the load equivalent resistance R4 only at the switching frequency of the switching signal, and harmonic frequencies are significantly suppressed, which helps to further improve efficiency.

[0156] Furthermore, the second inductor L2 and capacitors C1 and C2 form an LC load network or matching network configured to operate with a low-ohm load, helping to match the output impedance of the DC / AC converter with the load equivalent resistance R4. Specifically, capacitors C1 and C2 are tuned to reduce the ohm load of the second inductor L2 relative to the susceptor element, so that more heat is dissipated in the susceptor element compared to the inductor L2, which is desirable for heating the aerosol-forming substrate.

[0157] Circuit 400 has relatively few components compared to other drive and sensing circuits for induction heating aerosol generation systems, and therefore the printed circuit board area required to mount these components can be kept small, which helps to reduce the overall dimensions of the aerosol generator 60. Furthermore, the number of components can be further reduced by using a second inductor L2 in the DC / AC conversion.

[0158] During operation, the second inductor L2 generates an alternating magnetic field that induces eddy currents within the first susceptor element 316 and the second susceptor element of the cartridge 10 in Figure 11, thereby heating the first susceptor element 316 and the second susceptor element. As the first susceptor element 316 and the second susceptor element heat up during operation, the liquid aerosol-forming substrate supplied from the liquid reservoir 344 to the first susceptor element 316 and the second susceptor element via the liquid delivery element 320 is vaporized.

[0159] The inventors recognized that while the liquid aerosol-forming substrate is supplied to the first susceptor element 316 and the second susceptor element, and while the liquid aerosol-forming substrate is aerosolized, the temperature and apparent resistance of the first susceptor element 316 and the second susceptor element remain substantially constant. However, if the supply of the liquid aerosol-forming substrate to the first susceptor element 316 and the second susceptor element decreases or stops, the temperature and apparent resistance of the first susceptor element 316 and the second susceptor element increase as the liquid reservoir 344 is depleted, thereby increasing the equivalent resistance R4 and the DC current I drawn by the circuit 400 at a constant voltage. DC It decreases.

[0160] The heating circuit 400 in Figure 12 further comprises a power measurement unit 410, indicated by a dashed box. The function of the power measurement unit 410 is to measure the power delivered to the induction coil L2 and the susceptor element. The power measurement unit is configured to measure the voltage and current supplied to the induction coil L2. The power measurement unit 410 of the induction heating circuit 400 in Figure 12 is substantially identical to the power measurement unit 210 in Figure 7, and therefore will not be described in detail again here.

[0161] The current measurement section of the power measurement unit 210 is a shunt resistor R shunt , as well as shunt resistor R shunt The operational amplifier 420 has inputs connected to both sides of and an output connected to the ADC input of a control unit (not shown), for example, control unit 208 in Figures 7 and 8. The operational amplifier 220 is connected to a shunt resistor R shunt It provides an amplified voltage signal proportional to the voltage across its terminals. (Shunter resistor R) shunt Current I passes through it DC This is equal to the current supplied to the heating circuit 204. Shunt resistor R shunt Current I passes through it DC This is a shunt resistor R shunt The voltage across both ends and the shunt resistor R shunt This can be determined by applying Ohm's law (see equation 2 above) to the known resistance.

[0162] As described above, Class E power amplifiers have been found to be a highly efficient means of transferring power to the load equivalent resistance R4. shunt DC current I DC This displays the current supplied to the load equivalent resistance R4. Furthermore, resistor R shunt The resistance value is relatively small, therefore resistor R shunt The voltage drop across the terminals can be practically ignored.

[0163] The voltage measuring component of the power management unit 410 comprises a voltage or potential divider formed by resistors R1 and R2, which have equal resistance values, such that the voltage at point Y between resistors R1 and R2 is equal to half the input voltage Vin at point X of circuit 400. Point Y is connected to the ADC input of a control unit (not shown), for example, control unit 208 in Figures 7 and 8, to provide the control unit with a voltage signal corresponding to the voltage at point Y. This allows the control unit to determine the input voltage Vin by doubling the voltage signal received from point Y. Resistors R1 and R2 have relatively high resistance values ​​to reduce the current drawn through the voltage divider. The power supplied to the induction coil L2 is determined by the control unit in the same manner as described above with respect to Figure 7.

[0164] The input to the heating circuit 400 in Figure 12 is connected to the output of a DC / DC voltage converter (not shown) used to reduce the power supplied to the circuit 400, and a DC / AC converter is then used to supply the reduced AC voltage and current to the induction coil L2. However, it will be understood that a DC / DC voltage converter is not necessary, and the input voltage Vin can be supplied directly from a DC power source using a DC / AC converter that controls the power supplied to the induction coil L2 that heats the susceptor element. Since the equivalent resistance R4 of the induction coil L2 and the susceptor element can be seen as an impedance with a very low ohm value, the DC-AC converter needs to operate at a higher frequency and lower voltage compared to a heater with a higher impedance value. However, by changing the frequency of the AC voltage generated by the DC / AC converter, the same given power profile can be applied to the induction coil without using a DC / DC voltage converter. In this regard, a higher AC frequency can be used with a low impedance heater to avoid excessively high current, which avoids the need for a high impedance heater.

[0165] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers representing amounts, quantities, proportions, etc., are understood to be modified in all cases by the term “approximately.” Furthermore, all ranges include the disclosed maximum and minimum points and any intermediate ranges therewith, which may or may not be specifically listed herein. Thus, in this context, number A is understood as A ± 5 percent (5%). In this context, number A may be considered to include a numerical value that falls within the general standard error of the measurement of the characteristic modified by number A. Number A may deviate by the proportions listed above, provided that in some cases, such as those used in the appended claims, the amount by which A deviates does not substantially affect the fundamental and novel characteristics of the claimed invention. Furthermore, all ranges include the disclosed maximum and minimum points and any intermediate ranges therewith, which may or may not be specifically listed herein.

Claims

1. an aerosol generation system, A DC power supply for generating a DC supply voltage, and A control circuit for controlling the power supply from the DC power source to the heater for aerosolization of a liquid aerosol-forming substrate, A DC / DC voltage converter is provided to receive the aforementioned DC supply voltage as input and to output an output voltage for supplying power to the heater, A control circuit comprises a control unit configured to control the DC / DC voltage converter and adjust the output voltage based on a predetermined power profile of the heater, The predetermined power profile is The first power value is supplied to the heater during the first period, and The second period after the first period includes a second power value supplied to the heater, An aerosol generating system in which the second power value is smaller than the first power value.

2. The aerosol generating system according to claim 1, wherein the DC / DC voltage converter is a step-down converter or a buck converter such that the output voltage is less than the DC supply voltage.

3. The aerosol generating system according to claim 1 or 2, wherein the heater comprises a resistance heater having an electrical resistance of 0.2 to 1 ohm at room temperature.

4. The aerosol generating system according to claim 3, wherein the heater comprises a resistance heater having an electrical resistance of 0.2 to 0.5 ohms at room temperature.

5. The aerosol generating system according to any one of claims 1 to 4, wherein the first power value is configured to heat the heater at a predetermined speed.

6. The aerosol generating system according to any one of claims 1 to 5, wherein the second power value is configured to maintain the heater at a temperature above the boiling point of the liquid aerosol forming substrate.

7. The aerosol generating system according to any one of claims 1 to 6, wherein the second power value is configured to heat the heater such that the aerosolization rate of the liquid aerosol-forming substrate from the heater is less than or equal to the liquid flow rate of the liquid aerosol-forming substrate in the liquid delivery element of the heater.

8. The aerosol generating system according to any one of claims 1 to 7, wherein the first power value is in the range of 6 to 10 watts, preferably 7 to 9 watts.

9. The aerosol generating system according to any one of claims 1 to 8, wherein the second power value is in the range of 4 to 7 watts.

10. The aerosol generating system according to any one of claims 1 to 9, wherein the control unit is configured to control the DC / DC voltage converter without using a temperature sensor or a resistance measuring sensor.

11. The aerosol generating system according to any one of claims 1 to 10, further comprising a power measuring unit for determining the power supplied to the heater, wherein the power measuring unit is connected to a control unit, enabling the control unit to control the DC / DC voltage converter based on one or more signals received from the power measuring unit.

12. The aerosol generating system according to claim 11, wherein the power measuring unit is configured to measure the current passing through the resistance heater and the voltage across the resistance heater so that the control unit can determine or calculate the power.

13. The aerosol generation system according to claim 11 or 12, wherein the power measurement unit comprises a shunt resistor and an operational amplifier, the operational amplifier having an input connected to both ends of the shunt resistor for measuring the voltage across both ends of the shunt resistor, and an output connected to the control unit.

14. The aerosol generating system according to claim 13, wherein the shunt resistor is connected in series with the heater.

15. The aerosol generating system according to claim 14, wherein the shunt resistor has a resistance of less than 20 milliohms, preferably less than 10 milliohms, and more preferably less than 5 milliohms.

16. A method for controlling an aerosol generator, wherein the aerosol generator comprises a DC power supply and a control circuit for controlling the supply of power from the DC power supply to a heater for aerosolizing a liquid aerosol-forming substrate, the control circuit comprises a DC / DC voltage converter, and the DC / DC voltage converter is configured to receive a DC supply voltage as input from the DC power supply and output an output voltage for supplying power to the heater, the method being described above. This includes controlling the DC / DC voltage converter to adjust the output voltage based on a predetermined power profile of the heater, The predetermined power profile is The first power value is supplied to the heater during the first period, and The second period after the first period includes a second power value supplied to the heater, A method for controlling an aerosol generator, wherein the second power value is smaller than the first power value.

Images