A heated aerosol generator and a method for generating aerosols with consistent characteristics.

Abstract

To provide a method for controlling the generation of aerosol in an aerosol generation device.SOLUTION: An aerosol generation device includes a heater including at least one heating element configured so as to heat an aerosol forming base material and a power source for supplying power to the heating element. A method for controlling the generation of aerosol includes a step to control the power to be supplied to the heating element so that power is supplied in order for the temperature of the heating element to increase from an initial temperature to a first temperature in a first stage, power is supplied in order for the temperature of the heating element to decrease to a second temperature lower than the first temperature in a second stage, and power is supplied in order for the temperature of the heating element to increase again in a third stage. When the temperature of the heating element is caused to increase in a final stage of the heating process, a decrease in aerosol delivery by a lapse of time is reduced or prevented.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an aerosol generating device and a method for generating an aerosol by heating an aerosol forming substrate. In particular, the present invention relates to an apparatus and method for generating an aerosol of consistent desired properties from an aerosol forming substrate over a continuous or repeated heating period of the aerosol forming substrate.

Background Art

[0002] In the art, aerosol generating devices that operate by heating an aerosol forming substrate, such as heated smoking devices, are known. WO 2009 / 118085 describes a heated smoking device that generates an aerosol by heating a substrate while controlling the temperature within a temperature range desirable for preventing combustion of the substrate.

[0003] It is desirable for an aerosol generating device to be able to produce a consistent aerosol over time. This is particularly true when the aerosol is consumed by a human, such as in the case of a heated smoking device. In devices where a consumable substrate is heated continuously or repeatedly over a period of time, consistent aerosol generation can be difficult because the properties of the aerosol forming substrate can change significantly with continuous or repeated heating, both in terms of the amount and distribution of aerosol forming components remaining in the substrate and the temperature of the substrate. In particular, users of continuous or repeated heating devices may experience a fading of the aroma, taste and sensation of the aerosol as aerosol forming entities that deliver nicotine and, in some cases, flavorants, deplete from the substrate. Therefore, achieve consistent aerosol delivery over time such that the aerosol initially delivered during operation is approximately the same as the aerosol delivered last.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] The object of this disclosure is to provide an aerosol generator and system that provides an aerosol with more consistent properties over a continuous or repeated heating period of an aerosol-forming substrate. [Means for solving the problem]

[0006] In a first aspect, the present disclosure provides a method for controlling the generation of aerosols in an aerosol generator, the generator being A heater comprising at least one heating element configured to heat an aerosol-forming substrate, A power supply for providing power to the heating element, The method comprises the steps of controlling the power supplied to the heating element such that, in the first stage, power is supplied so that the temperature of the heating element rises from an initial temperature to a first temperature; in the second stage, power is supplied so that the temperature of the heating element falls to a second temperature lower than the first temperature; and in the third stage, power is supplied so that the temperature of the heating element rises to a third temperature higher than the second temperature.

[0007] As used herein, "aerosol generator" refers to a device that generates an aerosol by interacting with an aerosol-forming substrate. The aerosol-forming substrate can be a part of an aerosol-generating article, such as a part of a smoking article. The aerosol generator can be a smoking article that interacts with the aerosol-forming substrate of an aerosol-generating article to generate an aerosol that can be directly inhaled into the user's lungs through the user's mouth. The aerosol generator can be a holder.

[0008] As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form aerosols. Such volatile compounds can be released by heating the aerosol-forming substrate. For convenience, the aerosol-forming substrate may be part of an aerosol-generating article or a smoking article.

[0009] As used herein, the terms “aerosol-generating article” and “smoking article” refer to articles comprising an aerosol-forming substrate capable of releasing volatile compounds that can form aerosols. For example, an aerosol-generating article may be a smoking article that generates an aerosol that can be directly inhaled into the user's lungs through the user's mouth. Aerosol-generating articles may be disposable. Hereafter, the term “smoking article” will be used in general. A smoking article may be a tobacco stick, or may contain a tobacco stick.

[0010] Conventional aerosol generators, which typically generate aerosols by repeatedly or continuously heating a substrate, are controlled to achieve a single, constant temperature over time. However, the aerosol-forming substrate is depleted by heating, meaning that the amount of major aerosol components in the substrate decreases, which in turn reduces aerosol generation at a given temperature. Furthermore, once the temperature of the aerosol-forming substrate reaches a steady state, the thermal diffusion effect decreases, reducing aerosol delivery. As a result, in the case of heated smoking devices, the delivery of major aerosol components, such as nicotine, decreases over time. Increasing the temperature of the heating element during the final stage of the heating process can mitigate or prevent the decrease in aerosol delivery over time.

[0011] In this context, continuous or repeated heating means heating a substrate or a portion of a substrate for a duration typically longer than 5 seconds, and sometimes longer than 30 seconds, to generate an aerosol. In the context of heated smoking devices, or other devices in which a user inhales smoke to draw an aerosol from the device, this means heating the substrate so that an aerosol is continuously generated over a period including multiple user inhalations, regardless of whether the user is inhaling smoke from the device or not. In this context, substrate depletion becomes a significant issue. This is in contrast to instantaneous heating, where a separate substrate or portion of a substrate is heated with each user inhalation, and the substrate portion is not heated for a duration longer than a single inhalation, which is approximately 2-3 seconds.

[0012] In this specification, the terms “inhalation” and “smoke inhalation” are used synonymously, both referring to the act of a user drawing an aerosol into their body through their mouth or nose. Inhalation includes situations in which the aerosol is drawn into the user’s lungs, as well as situations in which the aerosol is drawn only into the user’s mouth or nasal cavity before being expelled from the user’s body.

[0013] The first, second, and third temperatures are selected so that aerosols are continuously generated during the first, second, and third stages. Preferably, the first, second, and third temperatures are determined based on a temperature range corresponding to the volatilization temperature of the aerosol-forming material present in the substrate. For example, when glycerin is used as the aerosol-forming material, a temperature of 290 to 320 degrees Celsius or higher (i.e., a temperature higher than the boiling point of glycerin) is used. During the second stage, power can be supplied to the heating element to ensure that the temperature does not fall below the minimum allowable temperature.

[0014] In the first stage, the temperature of the heating element is raised to a first temperature at which aerosol is generated from the aerosol-forming substrate. In many devices, especially heated smoking devices, it is desirable to generate an aerosol containing the desired components as quickly as possible after the device is activated. The "time to first puff" is considered extremely important for a satisfactory consumer experience with heated smoking devices. Consumers do not want to have to wait a long time from the activation of the device until their first puff. Therefore, in the first stage, power can be supplied to the heating element to raise it to the first temperature as quickly as possible. The first temperature can be selected to fall within an acceptable temperature range, but it can be selected near the maximum acceptable temperature to generate a satisfactory amount of aerosol for the initial delivery to the consumer. During the initial operating time of the device, aerosol delivery is reduced due to condensation within the device.

[0015] The permissible temperature range depends on the aerosol-forming substrate. Aerosol-forming substrates release a range of volatile compounds at different temperatures. Some volatile compounds released from aerosol-forming substrates are formed only through the heating process. Each volatile compound is released above its specific release temperature. By controlling the maximum operating temperature to below the release temperatures of certain volatile compounds, the release or formation of these volatile compounds can be avoided. The maximum operating temperature can also be selected to ensure that combustion of the substrate does not occur under normal operating conditions.

[0016] The permissible temperature range can have a lower limit of 240°C to 340°C and an upper limit of 340°C to 400°C, preferably 340°C to 380°C. The first temperature can be 340°C to 400°C. The second temperature can be 240°C to 340°C, preferably 270°C to 340°C, and the third temperature can be 340°C to 400°C, preferably 340°C to 380°C. It is preferable that the maximum operating temperatures of the first, second, and third temperatures do not exceed the combustion temperature of undesirable compounds present in conventional cigarettes with ignition ends or approximately 380°C.

[0017] In the second and third stages, it is advantageous to control the power supplied to the heating element in order to maintain the temperature of the heating element within an acceptable or desired temperature range.

[0018] There are many possibilities for determining when to transition from the first to the second stage, and similarly, when to transition from the second to the third stage. In one embodiment, each of the first, second, and third stages may have a predetermined duration. In this embodiment, the time after the device has been operating is used to determine when to start and end the second and third stages. In another example, the first stage may end as soon as the heating element reaches a first target temperature. In yet another example, the first stage ends based on a predetermined time after the heating element has reached the first target temperature. In yet another example, the first and second stages can be ended based on the total energy delivered to the heating element after operation. In yet another example, the device may be configured to detect smoke extraction by the user, for example using a dedicated flow sensor, and the first and second stages can be ended after a predetermined number of smoke extractions. It will be apparent that combinations of these options can be applied to the transition of any two stages. It will also be apparent that the operating stages of the heating element may be more than three different.

[0019] Once the first stage is complete, the second stage begins, controlling the power supplied to the heating element so that its temperature drops to a second temperature, which is lower than the first temperature but still within the allowable temperature range. This decrease in the heating element's temperature is desirable because, once the device and substrate are heated, condensation is suppressed at a predetermined heating element temperature, increasing aerosol delivery. After the first stage, it is also desirable to lower the heating element's temperature to reduce the possibility of the substrate burning. Furthermore, lowering the heating element's temperature reduces the amount of energy consumed by the aerosol generator. Additionally, by changing the heating element's temperature during the device's operation, a time-modulated temperature gradient can be introduced to the substrate.

[0020] In the third stage, the temperature of the heating element is increased. During the third stage, it is desirable to continuously increase the temperature as the substrate becomes increasingly depleted. Increasing the temperature of the heating element during the third stage compensates for the decrease in aerosol delivery due to substrate depletion and reduced heat diffusion. However, the temperature increase of the heating element during the third stage can have any desired temporal profile and may depend on the shape of the apparatus and substrate, the composition of the equipment, and the duration of the first and second stages. It is desirable that the temperature of the heating element be kept within an acceptable range throughout the third stage. In one embodiment, the step of controlling the power to the heating element is performed to continuously increase the temperature of the heating element during the third stage.

[0021] The step of controlling the power to the heating element can include measuring the temperature of the heating element or the temperature near the heating element to provide a measured temperature, comparing the measured temperature with a target temperature, and based on this comparison result, adjusting the power supplied to the heating element. The target temperature preferably changes with the time brought about by the first, second, and third stages after the operation of the device. For example, during the first stage, the target temperature can be set to a first target temperature, during the second stage, the target temperature can be set to a second target temperature, and during the third stage, the target temperature can be set to a third target temperature, and the third target temperature gradually increases with time. It will be clear that the target temperature can be selected to have any desired temporal profile within the constraints of the first, second, and third operating stages.

[0022] The heating element can be an electrically resistive heating element, and the step of controlling the power supplied to the heating element can include measuring the electrical resistance of the heating element and adjusting the current supplied to the heating element depending on the measured electrical resistance. The electrical resistance of the heating element indicates the temperature of the heating element, and thus the measured electrical resistance can be compared with a target electrical resistance and the supplied power adjusted accordingly. A PID control loop can be used to lead the measured temperature to the target temperature. Further, in addition to or instead of detecting the electrical resistance of the heating element, a mechanism for detecting temperature such as a bimetal plate, a thermocouple or a dedicated thermistor, or an electrical resistance element electrically separated from the heating element can also be used. These optional temperature detection mechanisms can be used in addition to or instead of the temperature measurement by monitoring the electrical resistance of the heating element. For example, a separate temperature detection mechanism can be used within a control mechanism for reducing the power to the heating element when the temperature of the heating element exceeds the allowable temperature range.

[0023] The method can further include the step of identifying the characteristics of the aerosol-forming substrate. Thereafter, depending on the identified characteristics, the step of controlling the power can be adjusted. For example, different target temperatures can be used for different substrates.

[0024] In a second aspect of the present invention, there is provided an electrically operated aerosol generator, the device comprising: at least one heating element configured to heat an aerosol-forming substrate to generate an aerosol; a power source for supplying power to the heating element; an electrical circuit for controlling the supply of power from the power source to the at least one heating element; and the electrical circuit is configured to control the power supplied to the heating element such that in a first stage, the temperature of the heating element rises from an initial temperature to a first temperature, in a second stage, the temperature of the heating element drops below the first temperature, and in a third stage, the temperature of the heating element rises again, with power being continuously supplied during the first, second, and third stages.

[0025] Options regarding the duration of each stage and the temperature of the heating element during each stage are as described in relation to the first aspect. The electrical circuit can be configured such that each of the first, second, and third stages has a constant duration. The electrical circuit can be configured to control the power supplied to the heating element such that the temperature of the heating element continuously rises during the third stage.

[0026] This circuit can be configured to supply power to the heating element as current pulses. And the power supplied to the heating element can be adjusted by adjusting the duty cycle of the current. This duty cycle can be adjusted by changing the pulse width or the frequency of the pulses, or both. Alternatively, the circuit can also be configured to supply power to the heating element as a continuous DC signal.

[0027] The electrical circuit may include temperature sensing means configured to measure the temperature of the heating element or the temperature near the heating element and provide a measured temperature, and may also be configured to compare the measured temperature with a target temperature and adjust the power supplied to the heating element based on this comparison. The target temperature may be stored in electronic memory and preferably changes over time as the first, second, and third stages of the device are brought about after operation.

[0028] The temperature sensing means can be a dedicated electrical component such as a thermistor, or a circuit configured to measure temperature based on the electrical resistance of the heating element.

[0029] The electrical circuit may further include means for identifying the properties of an aerosol-forming substrate within the device, and a memory for holding power control commands and a lookup table of the properties of the corresponding aerosol-forming substrate.

[0030] In the first and second aspects of the present invention, the heating element may include an electrical resistance material. Suitable electrical resistance materials include, but are not limited to, doped ceramics, "conductive" ceramics (such as molybdenum disilide), carbon, graphite, metals, metal alloys, and semiconductors such as composite materials made of ceramic and metal materials. Such composite materials may include doped or undoped ceramics. An example of a suitable doped ceramic is doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, platinum, gold, and silver. Examples of suitable metal alloys include stainless steel, nickel-containing alloys, cobalt-containing alloys, chromium-containing alloys, aluminum-containing alloys, titanium-containing alloys, zirconium-containing alloys, hafnium-containing alloys, niobium-containing alloys, molybdenum-containing alloys, tantalum-containing alloys, tungsten-containing alloys, tin-containing alloys, gallium-containing alloys, manganese-containing alloys, gold-containing alloys, and iron-containing alloys, as well as nickel, iron, cobalt, stainless steel, superalloys based on Timetal®, and iron-manganese-aluminum-based alloys. In composite materials, depending on the dynamics of energy transfer and the required external physicochemical properties, electrical resistive materials can be arbitrarily embedded in insulating materials, or encapsulated or coated with insulating materials, or vice versa.

[0031] In the first and second aspects of the present invention, the aerosol generator may include an internal heating element, an external heating element, or both, where "internal" and "external" refer to the aerosol-forming substrate. The internal heating element can take any suitable form. For example, the internal heating element may take the form of a heating blade. Alternatively, this internal heater may take the form of a casing or substrate having different conductive parts, or an electrically resistive metal tube. Alternatively, the internal heating element may be one or more heating needles or rods passing through the center of the aerosol-forming substrate. Other options include, for example, heating wires or filaments such as Ni-Cr (nickel-chromium), platinum, tungsten, or alloy wire, or heating plates. Optionally, the internal heating element may be deposited in or on a rigid carrier material. In one such embodiment, an electrically resistive heating element can be formed using a metal having a specified temperature-resistivity relationship. In such an exemplary apparatus, the metal can be formed as a track on a suitable insulating material such as a ceramic material and sandwiched between other insulating materials such as glass. Using the heater formed in this way, both heating of the heating element and temperature monitoring can be performed during operation.

[0032] The external heating element can take any suitable form. For example, the external heating element can take the form of one or more flexible heating foils on a dielectric substrate such as polyimide. These flexible foils can be molded to fit the outer circumference of the substrate receiving cavity. Alternatively, the external heating element can take the form of one or more metal grids, flexible circuit boards, molded interconnect devices (MIDs), ceramic heaters, flexible carbon fiber heaters, or be formed on a suitable molded substrate using coating techniques such as plasma deposition. The external heating element can also be formed using a metal having a specified temperature-resistivity relationship. In such an exemplary device, this metal can be formed as a track between layers of two suitable insulating materials. Using the external heating element thus formed, both heating of the external heating element and temperature monitoring can be performed during operation.

[0033] Internal or external heating elements may include a heat sink or a heat storage body containing a material that can absorb and store heat and then release that heat to the aerosol-forming substrate over time. The heat sink can be formed from any suitable material, such as a suitable metal or ceramic material. In one embodiment, this material has a high heat capacity (sensible heat storage material) or is a material that can release heat after absorbing heat through a reversible process such as a high-temperature phase change. Suitable sensible heat storage materials include silica gel, alumina, carbon, glass mat, glass fiber, minerals, metals or alloys such as aluminum, silver or lead, and cellulose materials such as paper. Other suitable materials that release heat through a reversible phase change include paraffin, sodium acetate, naphthalene, wax, polyethylene oxide, metals, metal salts, mixtures of eutectic salts, or alloys. The heat sink or heat storage body may be configured to be in direct contact with the aerosol-forming substrate so that the stored heat can be directly transferred to the substrate. Alternatively, the heat stored in the heat sink or heat storage body can be transferred to the aerosol-forming substrate using a heat conductor such as a metal tube.

[0034] The heating element is advantageous in that it heats the aerosol-forming substrate by thermal conduction. The heating element can be in at least partial contact with the substrate, or the carrier on which the substrate is deposited. Alternatively, heat from either an internal or external heating element can be conducted to the substrate by a thermal conduction element.

[0035] In the first and second aspects of the present invention, the aerosol-forming substrate can be completely housed in the aerosol generator during operation. In this case, the user can blow into the mouthpiece of the aerosol generator. Alternatively, the smoking article containing the aerosol-forming substrate can be partially housed in the aerosol generator during operation. In this case, the user can blow into the smoking article directly. A heating element can be located within a cavity of the device, which is configured to receive the aerosol-forming substrate such that the heating element is located within the aerosol-forming substrate during use.

[0036] The smoking article may be substantially cylindrical in shape. The smoking article may be substantially elongated. The smoking article may have a length and a circumference substantially perpendicular to this length. The aerosol-forming substrate may be substantially cylindrical in shape. The aerosol-forming substrate may be substantially elongated. The aerosol-forming substrate may also have a length and a circumference substantially perpendicular to this length.

[0037] The smoking article may have an overall length of approximately 30 mm to approximately 100 mm. The smoking article may have an outer diameter of approximately 5 mm to approximately 12 mm. The smoking article may include a filter plug. The filter plug may be located at the downstream end of the smoking article. The filter plug may be a cellulose acetate filter plug. In one embodiment, the filter plug is approximately 7 mm in length, but can have a length of approximately 5 mm to approximately 10 mm.

[0038] In one embodiment, the smoking article has an overall length of about 45 mm. The smoking article may have an outer diameter of about 7.2 mm. Furthermore, the aerosol-forming substrate may have a length of about 10 mm. Alternatively, the aerosol-forming substrate may have a length of about 12 mm. Furthermore, the diameter of the aerosol-forming substrate may be about 5 mm to about 12 mm. The smoking article may include an outer paper flaps. Furthermore, the smoking article may have a separation distance between the aerosol-forming substrate and the filter plug. This separation distance may be about 18 mm, but may be about 5 mm to about 25 mm. This separation distance is preferably filled within the smoking article by a heat exchanger that cools the aerosol as it passes through the smoking article from the substrate to the filter plug. The heat exchanger may be a polymer filter, such as a crumpled PLA material.

[0039] In the first and second aspects of the present invention, the aerosol-forming substrate can be a solid aerosol-forming substrate. Alternatively, the aerosol-forming substrate may contain both solid and liquid components. The aerosol-forming substrate may contain a tobacco-containing material that includes volatile tobacco flavor compounds released from the substrate upon heating. Alternatively, the aerosol-forming substrate may contain a non-tobacco material. The aerosol-forming substrate may further contain an aerosol-forming body. Examples of suitable aerosol-forming bodies include glycerin and propylene glycol.

[0040] If the aerosol-forming substrate is a solid aerosol-forming substrate, it may include one or more powders, granules, pellets, flakes, threads, strips, or sheets containing, for example, one or more of herb leaves, tobacco leaves, tobacco stem fragments, reconstituted tobacco, homogenized tobacco, extracted tobacco, molded tobacco, and expanded tobacco. The solid aerosol-forming substrate may be supplied in loose form or in a suitable container or cartridge. Optionally, the solid aerosol-forming substrate may also contain additional tobacco or non-tobacco volatile flavor compounds released when the substrate is heated. The solid aerosol-forming substrate may also contain capsules containing additional tobacco or non-tobacco volatile flavor compounds, such capsules which can be dissolved during heating of the solid aerosol-forming substrate.

[0041] As used herein, homogenized tobacco means a material formed by forming particulate tobacco into clumps. Homogenized tobacco can take the form of a sheet. Homogenized tobacco material may have an aerosol-forming content of more than 5% by dry weight. Alternatively, homogenized tobacco material may have an aerosol-forming content of 5 to 30% by dry weight. Sheets of homogenized tobacco material can be formed by forming clumps of particulate tobacco obtained by grinding or otherwise crushing one or both of the leaf blades and / or stems of tobacco leaves. Separately or in addition thereto, sheets of homogenized tobacco material may also contain one or more of the following, for example, tobacco scraps, tobacco powder, and other particulate tobacco formed as by-products during the processing, handling, and shipment of tobacco. A sheet of homogenized tobacco material may contain one or more endogenous binders originating from within the tobacco, one or more exogenous binders originating from outside the tobacco, or a combination thereof, to assist in forming clumps of particulate tobacco. In addition to or separately therefrom, the sheet of homogenized tobacco material may also contain other additives, including, but not limited to, tobacco and non-tobacco fibers, aerosol formers, humectants, plasticizers, flavorings, fillers, aqueous and non-aqueous solvents, and combinations thereof.

[0042] Optionally, the solid aerosol-forming substrate may be provided on or embedded in a thermally stable carrier. This carrier may take the form of powder, granules, pellets, fragments, threads, strips, or sheets. Alternatively, the carrier may be a tubular carrier in which a thin layer of the solid substrate is deposited on its inner surface, outer surface, or both. Such a tubular carrier may be formed from, for example, paper or paper-like material, nonwoven carbon fiber mat, low-mass mesh metal screen or perforated metal foil, or any other thermally stable polymer matrix.

[0043] The solid aerosol-forming substrate can be deposited on the surface of a carrier, for example, in the form of a sheet, foam, gel, or slurry. The solid aerosol-forming substrate can be deposited over the entire surface of the carrier, or it can be deposited in a specific pattern to ensure uneven flavor delivery during use.

[0044] While solid aerosol-forming substrates have been described above, it will be apparent to those skilled in the art that other forms of aerosol-forming substrates can be used in other embodiments. For example, the aerosol-forming substrate may be a liquid aerosol-forming substrate. When a liquid aerosol-forming substrate is provided, the aerosol generator preferably has means for holding the liquid. For example, the liquid aerosol-forming substrate can be held in a container. Separately or in addition to this, the liquid aerosol-forming substrate can also be absorbed into a porous carrier material. The porous carrier material can be formed from any suitable absorbent plug or absorbent, such as foamed metal or plastic material, polypropylene, terylene, nylon fiber, or ceramic. The liquid aerosol-forming substrate can be held in the porous carrier material before use of the aerosol generator, or the liquid aerosol-forming substrate material can be released into the porous carrier material during or immediately before use. For example, the liquid aerosol-forming substrate can be provided in a capsule. The capsule shell preferably melts upon heating to release the liquid aerosol-forming substrate into the porous carrier material. The capsule may optionally contain a solid in combination with the liquid.

[0045] Alternatively, the carrier may be a nonwoven fabric or fiber bundle incorporating tobacco components. This nonwoven fabric or fiber bundle may include, for example, carbon fibers, natural cellulose fibers, or cellulose-derived fibers.

[0046] In the first and second embodiments of the present invention, the aerosol generator may further include a power source for supplying power to a heating element. This power source can be any suitable power source, such as a DC voltage source. In one embodiment, the power source is a lithium-ion battery. Alternatively, the power source can be a nickel-metal hydride battery, a nickel-cadmium battery, or a lithium-based battery such as a lithium-cobalt battery, lithium iron phosphate battery, lithium titanate battery, or lithium polymer battery.

[0047] A third aspect of the present invention provides an electrical circuit for an electrically operated aerosol generator configured to carry out the method of the first aspect of the present invention.

[0048] A fourth aspect of the present invention provides a computer program that, when executed on a programmable electrical circuit for an electrically operated aerosol generator, causes the programmable electrical circuit to perform the method of the first aspect of the present invention. A fifth aspect of the present invention provides a computer-readable storage medium storing a computer program according to the fourth aspect of the present invention.

[0049] While the Disclosure has been described with reference to different aspects, it will be apparent that features described in relation to one aspect of the Disclosure can also be applied to other aspects of the Disclosure.

[0050] Hereinafter, embodiments of the present invention will be described in detail as just one example, with reference to the attached drawings. [Brief explanation of the drawing]

[0051] [Figure 1] This is a schematic diagram of an electrically heated smoking device according to the present invention. [Figure 2] This is a schematic cross-sectional view of the front end of a first embodiment of the type of device shown in Figure 1. [Figure 3] This is a schematic diagram of the flat temperature profile of the heating element. [Figure 4] This is a schematic diagram showing that aerosol delivery is reduced by a flat temperature profile. [Figure 5] This is a schematic diagram of the temperature profile of the heating element according to an embodiment of the present invention. [Figure 6] This is a schematic diagram of constant aerosol delivery according to an embodiment of the present invention. [Figure 7] This figure shows a control circuit used to adjust the temperature of a heating element according to one embodiment of the present invention. [Figure 8] This figure shows several different target temperature profiles according to the present invention. [Modes for carrying out the invention]

[0052] Figure 1 shows a simplified representation of the components of an embodiment of the electric heating aerosol generator 100. In detail, Figure 1 does not show the elements of the electric heating aerosol generator 100 to scale. In Figure 1, elements unrelated to understanding this embodiment have been omitted for simplification.

[0053] The electrically heated aerosol generator 100 comprises a housing 10 and an aerosol-forming substrate 12, such as a cigarette. The aerosol-forming substrate 12 is pushed into the housing 10 and is thermally close to the heating element 14. The aerosol-forming substrate 12 releases a range of volatile compounds at different temperatures. By controlling the operating temperature of the electrically heated aerosol generator 100 to be below the release temperature of some volatile compounds, the release or formation of components of these volatile compounds can be avoided.

[0054] An electrical energy source 16, such as a rechargeable lithium-ion battery, is located inside the housing 10. A controller 18 is connected to the heating element 14, the electrical energy source 16, and a user interface 20, such as a button or display. The controller 18 controls the power supplied to the heating element 14 in order to adjust its temperature. Typically, the aerosol-forming substrate is heated to a temperature of 250 to 450 degrees Celsius.

[0055] In the embodiment described, the heating element 14 is one or more electrical resistance tracks deposited on a ceramic substrate. The ceramic substrate is shaped like a blade and is inserted into the aerosol-forming substrate 12 when in use. Figure 2 is a schematic diagram of the front end of the device, showing the airflow within the device. Note that Figure 2 does not accurately show the relative dimensions of the elements of the device. The smoking article 102, including the aerosol-forming substrate 12, is received into the cavity 22 of the device 100. Air is drawn into the device by the user's action of sucking on the mouthpiece 24 of the smoking article 102. The air is drawn in through an inlet 26 that forms the proximal surface of the housing 10. The air drawn into the device passes through air channels 28 around the outside of the cavity 22. The drawn air enters the aerosol-forming substrate 12 at the distal end of the smoking article 102 adjacent to the proximal end of the blade-shaped heating element 14 provided in the cavity 22. The inhaled air travels through the aerosol-forming substrate 12, carrying an aerosol with it, to the lip-side end of the smoking article 102. The aerosol-forming substrate 12 is a cylindrical plug made of tobacco-based material.

[0056] As shown in Figure 3, the current aerosol generator is configured to maintain a constant temperature during operation. After the device is activated, power is supplied to the heating element until the target temperature of 50 is reached. Once the target temperature of 50 is reached, the heating element is maintained at this temperature until the device is shut down. Figure 4 is a schematic diagram showing the delivery of major aerosol components using the flat temperature profile shown in Figure 3. Line 52 represents the amount of major aerosol components, such as glycerol or nicotine, delivered during the operation of the device. It can be seen that the delivery of components peaks and then decreases over time as the substrate is depleted and the heat diffusion effect weakens.

[0057] Figure 5 is a schematic diagram of the temperature profile of a heating element according to an embodiment of the present invention. Line 60 represents the temperature of the heating element over time.

[0058] In the first stage 70, the temperature of the heating element rises from ambient temperature to a first temperature 62. Temperature 62 is within the allowable temperature range between a minimum temperature 66 and a maximum temperature 68. The allowable temperature change is set so that desired volatile compounds volatilize from the substrate, but undesirable compounds that volatilize at higher temperatures do not. The allowable temperature range is also below the temperature at which combustion of the substrate could occur under normal operating conditions, i.e., normal temperature, pressure, humidity, user fume extraction operation, and air composition.

[0059] In the second stage 72, the temperature of the heating element decreases to a second temperature. The second temperature is within the acceptable temperature range, but is lower than the first temperature.

[0060] In the third stage 74, the temperature of the heating element gradually increases until the stop time 76. The temperature of the heating element is kept within the acceptable temperature range throughout the third stage.

[0061] Figure 6 is a schematic diagram of the delivery profile of the main aerosol components based on the temperature profile of the heating element shown in Figure 5. After an initial increase in delivery following the activation of the heating element, delivery remains constant until the heating element is stopped. The temperature increase in the third stage compensates for the depletion of the aerosol-forming material on the substrate.

[0062] Figure 7 shows a control circuit used to achieve the described temperature profile according to one embodiment of the present invention.

[0063] The heater 14 is connected to a battery via a connector 42. This battery (not shown in Figure 7) supplies voltage V2. A further resistor 44 of known resistance r is inserted in series with the heating element 14 and connected to a voltage V1 midway between ground and voltage V2. The frequency modulation of the current is controlled by a microcontroller 18 and delivered via its analog output 47 to a transistor 46 that functions as a simple switch.

[0064] This adjustment is based on a PID regulator, which is part of the software integrated into the microcontroller 18. The temperature (or temperature indication) of the heating element is determined by measuring the electrical resistance of the heating element. To maintain the heating element at a target temperature, or to adjust the temperature of the heating element toward the target temperature, this determined temperature is used to adjust the duty cycle (frequency modulation in this example) of the pulses of current supplied to the heating element. The temperature is determined at a frequency selected to fit the duty cycle control, and can be determined once every 100ms.

[0065] The analog input 48 to the microcontroller 18 is used to collect the voltage across resistor 44 and to provide an image of the current flowing through the heating element. The battery voltage V+ and the voltage across resistor 44 are used to calculate the resistance fluctuations of the heating element and / or its temperature.

[0066] The resistance of the heater measured at a specific temperature is R. heater The microprocessor 18 controls the resistor R of the heater 14. heater To measure this, both the current and voltage across heater 14 need to be determined. As a result, the resistance can be calculated using the following well-known formula. JPEG0007881789000001.jpg620(1)

[0067] In Figure 6, the heater voltage is V2-V1 and the heater current is I. Therefore, the following equation is obtained. JPEG0007881789000002.jpg1437(2)

[0068] Using another resistor 44 whose resistance r is known, we again use (1) above to find the current I. The current through resistor 44 is I, and the voltage across resistor 24 is V1. Therefore, the following equation is obtained. JPEG0007881789000003.jpg1417(3)

[0069] Therefore, combining (2) and (3), we obtain the following equation. JPEG0007881789000004.jpg1446(4)

[0070] Thus, the microprocessor 18 can measure V2 and V1 when the aerosol generation system is in use, and since the value of r is known, the heater resistance R at a specific temperature can be determined. heater It is possible to find this.

[0071] The heater resistance is correlated with temperature. Using a linear approximation, the resistance R measured at temperature T is given by the temperature T. heater The two can be related according to the following formula. JPEG0007881789000005.jpg1439(5) In the formula, A is the thermal resistivity coefficient of the heating element material, and R0 is the resistance of the heating element at room temperature T0.

[0072] If a simple linear approximation is insufficient over the operating temperature range, other, more complex methods can be used to approximate the relationship between resistance and temperature. For example, in another embodiment, the relationship can be derived based on a combination of two or more linear approximations, each covering a different temperature range. This scheme relies on three or more temperature calibration points where the heater's resistance is measured. At temperatures between these calibration points, the resistance value is interpolated from the calibration point value. The calibration point temperatures are selected to cover the expected temperature range of the heater in operation.

[0073] The advantage of these embodiments is that they do not require large and potentially expensive temperature sensors. Furthermore, the PID regulator can directly use resistance values ​​instead of temperature. This resistance value is directly correlated to the temperature of the heating element, as shown in equation (5). Therefore, if the measured resistance value is within the desired range, the temperature of the heating element is also within the desired range. Thus, there is no need to calculate the actual temperature of the heating element. However, it is also possible to connect a separate temperature sensor to a microcontroller to provide the necessary temperature information.

[0074] Figure 8 shows an example of a target temperature profile in which the three operating stages are clearly visible. In the first stage 70, the target temperature is set to T0. Power is supplied to the heating element to raise its temperature to T0 as quickly as possible. As described above, a PID regulator is used to keep the temperature of the heating element as close to the target temperature as possible throughout the operation of the device. At time t1, the target temperature has changed to T1, which means that the first stage 70 has ended and the second stage has begun. The target temperature is maintained at T1 until time t2. At time t2, the second stage has ended and the third stage 74 has begun. During the third stage 74, the target temperature increases linearly with time until time t3, at which time the target temperature becomes T2, and no further power is supplied to the heating element.

[0075] The target temperature profile for the shape shown in Figure 8 yields the actual temperature profile for the shape shown in Figure 5. The values ​​of T0, T1, and T2 can be adjusted to suit a specific substrate and specific device, heating element, and substrate shape. Similarly, the values ​​of t1, t2, and t3 can also be selected to suit the situation.

[0076] In one example, the first stage is 45 seconds long with T0 set to 360°C, the second stage is 145 seconds long with T1 set to 320°C, and the third stage is 170 seconds long with T2 set to 380°C. The smoking experience lasts for a total of 360 seconds.

[0077] In another example, the first stage is 60 seconds long with T0 set to 340°C, the second stage is 180 seconds long with T1 set to 320°C, and the third stage is 120 seconds long with T2 set to 360°C. In this case as well, the heating cycle or smoking experience lasts for a total of 360 seconds.

[0078] In yet another example, the first stage is 30 seconds long and T0 is set to 380°C, the second stage is 110 seconds long and T1 is 300°C, and the third stage is 220 seconds long and T2 is 340°C.

[0079] The duration and temperature targets for each operating stage are stored in the memory of the controller 18. This information can be part of the software executed by the microcontroller. Alternatively, this information can be stored in a lookup table so that the microcontroller can select different profiles. Consumers can select different profiles via a user interface based on their preferences or the specific substrate to be heated. The device may include substrate identification means, such as an optical reader, and a heating profile that is automatically selected based on the identified substrate.

[0080] In another embodiment, only the target temperatures T0, T1, and T2 are stored in memory, and the transition between each stage is triggered by the number of smoke extractions. For example, a microcontroller can receive smoke extraction data from a flow sensor and be configured to terminate the first stage after two smoke extractions and the second stage after a further five smoke extractions.

[0081] In each of the embodiments described above, the aerosol is delivered more evenly during heating of the substrate compared to the flat heating profile shown in Figure 3. The optimal heating profile depends on several factors and can be determined experimentally with respect to a given apparatus, substrate shape, and substrate composition. For example, the apparatus may include more than one heating element, and the configuration of the heating elements affects substrate depletion and heat diffusion effects. Each heating element can be controlled to have a different heating profile. The shape and size of the substrate relative to the heating element are also important factors.

[0082] It will be clear that the exemplary embodiments described above are illustrative and not limiting. Considering the exemplary embodiments described above, other embodiments according to these exemplary embodiments will already be apparent to those skilled in the art. [Explanation of Symbols]

[0083] 60 lines 62 First temperature 66 minimum temperature 68 Maximum temperature 70. Stage 1 72 Stage 2 74. Stage 3 76 Stop time

Claims

1. A method for controlling the generation of aerosols in an aerosol generator, wherein the device is The method includes a power supply (16) for supplying power to a heating element to heat an aerosol-forming substrate (12) containing an aerosol-forming body, and the method is as follows: The power supplied to the heating element includes the steps of: supplying power to the heating element in a first stage immediately after the device is activated so that the temperature of the heating element rises from an initial temperature to a first temperature; supplying power in a second stage so that the temperature of the heating element falls to a second temperature lower than the first temperature but not below the volatilization temperature of the aerosol forming material; and supplying power in a third stage so that the temperature of the heating element rises to a third temperature higher than the second temperature. A method characterized by the following:

2. The step of controlling the power supplied to the heating element (14) is performed in the second and third steps to maintain the temperature of the heating element within a desired temperature range. The method according to feature 1.

3. The desired temperature range has a lower limit of 240 degrees Celsius to 340 degrees Celsius and an upper limit of 340 degrees Celsius to 400 degrees Celsius. The method according to feature 2.

4. The first temperature is between 340 degrees Celsius and 400 degrees Celsius. The method according to any one of 1 to 3, characterized by the features described herein.

5. The first stage, the second stage, or the third stage has a predetermined duration. The method according to any one of 1 to 4, characterized by the features described herein.

6. The first step ends when the heating element (14) reaches the first temperature. The method according to any one of 1 to 5, characterized by the features described herein.

7. The second stage has a duration determined based on the total amount of power supplied to the heating element (14) during the second stage. The method according to any one of 1 to 6, characterized by the features described herein.

8. The first, second, or third step further includes detecting the user's inhalation of smoke from the aerosol generator, and the first, second, or third step ends after detecting a predetermined number of smoke inhalations by the user. The method according to any one of 1 to 7, characterized by the features described herein.

9. The step further includes identifying the properties of the aerosol-forming substrate, and the step of controlling the power is adjusted depending on the identified properties. The method according to any one of 1 to 8, characterized by the features described herein.

10. Aerosols are generated during each of the first, second, and third stages. The method according to any one of 1 to 9, characterized by the features described herein.

11. The substrate is heated for a duration longer than 5 seconds to generate an aerosol. The method according to any one of 1 to 10, characterized by the features described herein.

12. The aerosol-forming substrate is included in a smoking article partially contained within the aerosol generator. The method according to any one of 1 to 11, characterized by the features described herein.

13. The aerosol-forming substrate is a solid aerosol-forming substrate. The method according to any one of 1 to 12, characterized by the features described herein.

14. The step of controlling the power is performed such that the temperature of the heating element is continuously increased during the third stage. The method according to any one of 1 to 13, characterized by the features described herein.

15. An electrically operated aerosol generator, A power supply (16) for generating an aerosol by supplying power to a heating element (14) that heats an aerosol-forming substrate (12) containing an aerosol-forming material, An electrical circuit (18) for controlling the supply of power from the power source to the heating element, The electrical circuit is equipped with, The power supplied to the heating element is configured to control the temperature of the heating element so that in the first stage immediately after the operation of the device, the temperature of the heating element rises from the initial temperature to a first temperature; in the second stage, the temperature of the heating element falls to a second temperature lower than the first temperature but does not fall below the volatilization temperature of the aerosol forming material; and in the third stage, the temperature of the heating element rises to a third temperature higher than the second temperature, and power is supplied to the heating element during the first, second, and third stages. An electrically operated aerosol generator characterized by the following features.

16. The electrical circuit (18) is configured such that at least one of the first, second, and third stages has a constant duration. The electrically operated aerosol generator according to feature 15.

17. The electrical circuit (18) is configured to detect the user inhaling smoke from the aerosol generator, and to terminate after at least one of the first, second, or third stages has detected a predetermined number of times the user has inhaled smoke. The electrically operated aerosol generator according to claim 15 or 16.

18. The apparatus further comprises means for identifying the characteristics of the aerosol-forming substrate within the apparatus, and the electrical circuit (18) includes a memory that holds power control commands and a lookup table of the corresponding characteristics of the aerosol-forming substrate. The electrically operated aerosol generator according to claim 15, 16, or 17, characterized by the features described herein.

19. The heating element is located within the cavity (22) of the apparatus, and the cavity is configured to receive the aerosol-forming substrate (12) such that the heating element (14) is located within the aerosol-forming substrate (12) during use. The electrically operated aerosol generator according to any one of claims 15 to 18.

20. The heating element is configured to control the power supplied to the heating element so that an aerosol is generated during each of the first, second, and third stages. An electrically operated aerosol generator according to any one of claims 15 to 19.

21. The heating element is configured to control the power supplied to the heating element so as to heat the substrate for a duration longer than 5 seconds to generate an aerosol. An electrically operated aerosol generator according to any one of claims 15 to 20.

22. The aerosol-forming substrate is included in a smoking article partially contained within the aerosol generator. An electrically operated aerosol generator according to any one of claims 15 to 21.

23. The aerosol-forming substrate is a solid aerosol-forming substrate. An electrically operated aerosol generator according to any one of claims 15 to 22.

24. The heating element is configured to control the power supplied to the heating element so that the temperature of the heating element continuously rises during the third stage. An electrically operated aerosol generator according to any one of claims 15 to 23.

25. an aerosol generation system, A heating element (14) configured to generate an aerosol by heating an aerosol-forming substrate (12) containing an aerosol-forming body, A power supply (16) for supplying power to the heating element, An electrical circuit (18) for controlling the supply of power from the power source to the at least one heating element, The electrical circuit is equipped with, The power supplied to the heating element is configured to control the following: in the first stage immediately after the heating element is activated, the temperature of the heating element rises from the initial temperature to a first temperature; in the second stage, the temperature of the heating element falls to a second temperature lower than the first temperature but not below the volatilization temperature of the aerosol forming material; and in the third stage, the temperature of the heating element rises to a third temperature higher than the second temperature, and power is supplied to the heating element during the first, second, and third stages. An aerosol generation system characterized by the following features.

26. When performed on a programmable electrical circuit for an electrically operated aerosol generator, the programmable electrical circuit is made to perform the method according to claim 1. A computer program characterized by the following features.

27. The computer program described in claim 26 is stored A computer-readable storage medium characterized by the following features.

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