Heater assembly for use in aerosol generation systems

Abstract

A heater assembly (300) for use in an aerosol generation system (100) is provided. The heater assembly (300) includes a retaining material (302) containing an aerosol-forming substrate in condensed form. The aerosol-forming substrate includes a first compound and a second compound, the second compound having a higher boiling point than the first compound. At least one airflow path (306) is defined through the retaining material (302). The heater assembly (300) includes at least one heating element (304) shaped to define an interior volume, the interior volume being filled with the retaining material. The interior volume has a cross-sectional area that decreases along a longitudinal axis, and the at least one airflow path (306) passes through a first central region (312) of the interior volume and a second central region (310) of the interior volume, the first and second central regions (312, 310) being spaced apart along the longitudinal axis.

Description

【Technical Field】 【0001】 The present disclosure relates to a heater assembly for use in an aerosol generation system, an aerosol generation system including the heater assembly, a cartridge for use in an aerosol generation system including the heater assembly, and a method of using an aerosol generation system including the heater assembly. 【Background Art】 【0002】 In many well-known aerosol generation systems, a liquid aerosol-forming substrate is heated and vaporized to form a vapor. The vapor is cooled to form an aerosol. In some aerosol generation systems, such as an electrically heated smoking system, this aerosol is then inhaled by a user. 【0003】 Typically, a liquid aerosol-forming substrate includes several compounds that vaporize when heated. These compounds can have different boiling points. For example, a liquid aerosol-forming substrate may include nicotine (having a boiling point of about 247 °C at atmospheric pressure) and glycerol (having a boiling point of about 290 °C at atmospheric pressure). 【0004】 When a liquid aerosol-forming substrate having compounds with different boiling points is heated, the compounds with lower boiling points can vaporize before the compounds with higher boiling points. Alternatively, or additionally, the compounds with lower boiling points can vaporize at a higher rate than the compounds with higher boiling points. 【0005】 This may be undesirable because it may restrict the interactions and combinations between different compounds. For example, a liquid aerosol-forming substrate may contain nicotine compounds and organic acid compounds, and these compounds have different boiling points. Both of these compounds may vaporize. Nicotine in the liquid aerosol-forming substrate may form free base nicotine when vaporized. However, it may be desirable to generate an aerosol containing a nicotine salt rather than free base nicotine. To form this nicotine salt, the free base nicotine may be protonated by a vaporized organic acid. However, this protonation may be limited if the organic acid has not vaporized until after the nicotine has vaporized, or if it vaporizes more slowly than is required to protonate a suitable proportion of the free base nicotine. 【0006】 Furthermore, the rapid vaporization of some compounds in the aerosol-forming substrate compared to others is undesirable, as it can alter the properties of the generated aerosol over time, for example, during the fume extraction process in an aerosol-generating system. This is because, as the heating element is activated and the temperature rises towards the start of fume extraction, the liquid aerosol-forming substrate near the heating element may reach a first temperature where the first compound with a lower boiling point vaporizes, but the second compound with a higher boiling point does not. Later in the fume extraction process, the liquid aerosol-forming substrate near the heating element may reach a second temperature where the second compound with a higher boiling point vaporizes. However, by this time, most of the first compound in the liquid aerosol-forming substrate near the heating element may have already vaporized. Therefore, towards the start of fume extraction, the generated aerosol may contain a larger proportion of the first compound, and later in the fume extraction process, the generated aerosol may contain a larger proportion of the second compound. 【0007】 Alternatively, or additionally, the properties of the generated aerosol can change during the process of several vapor inhalations. This can occur if the compounds of the liquid aerosol-forming substrate are not vaporized at an appropriate rate. For example, the liquid aerosol-forming substrate may contain X mass percent of a first compound and Y mass percent of a second compound. If the liquid aerosol-forming substrate is not vaporized to produce a vapor containing the mass ratio X:Y of the first and second compounds, the composition of the liquid aerosol-forming substrate may change as the vapor is generated. This, in turn, can result in a change in the properties of the aerosol generated by the liquid aerosol-forming substrate. [Overview of the project] 【0008】 The objective of the present invention is to control the vaporization of various compounds of a liquid aerosol-forming substrate, which have different boiling points. 【0009】 This disclosure provides a heater assembly for use in an aerosol generating system. The heater assembly may include a retaining material. The retaining material may contain an aerosol-forming substrate. The retaining material may contain an aerosol-forming substrate in a condensed form. The aerosol-forming substrate may include a first compound and a second compound. The second compound may have a higher boiling point than the first compound. The heater assembly may have at least one airflow path defined through the retaining material. The heater assembly may have at least one heating element. At least one heating element may be shaped to define an internal volume. The internal volume may be filled with the retaining material. The internal volume may have a cross-sectional area that decreases along the longitudinal axis. At least one airflow path may pass through a first central region of the internal volume. At least one airflow path may pass through a second central region of the internal volume. The first and second central regions may be separated by a gap along the longitudinal axis. 【0010】 When used in an aerosol generation system, the heater assembly may be configured to generate vapor or aerosol by heating an aerosol-forming substrate. In particular, the heater assembly may be connectable to the power supply of the aerosol generation system so that power can be supplied to the heating element. In some embodiments, heat may be generated by the heating element repulsively or inductively. The heat may be transferred by conduction to a retaining material filling the internal volume. Alternatively, or additionally, the heating element may generate an alternating magnetic field, and the retaining material may include or consist of a susceptor element, and the susceptor of the retaining material may be inductively heated by the heating element. The heating element may be a coil. The heating element may be an inductor coil. In any case, the retaining material may be heated. Therefore, the aerosol-forming substrate contained in the retaining material may also be heated. This can vaporize the aerosol-forming substrate contained in the retaining material. The vapor generated in both the first and second central regions of the retaining material may enter at least one airflow path. This vapor may be cooled to form an aerosol, which can then be inhaled by the user through the mouthpiece of an aerosol generating system. 【0011】 The geometric shape of the internal volume defined by the heating element of the heater assembly can provide higher temperature and lower temperature regions within the retaining material. A first central region of the internal volume of the retaining material may be heated to a different temperature than a second central region. For example, the first central region may be heated to a lower temperature than the second central region. 【0012】 Alternatively, or additionally, the heater assembly may provide the storage component of the liquid aerosol-forming substrate with regions where the temperature rises at a greater rate and regions where the temperature rises at a lesser rate. 【0013】 Advantageously, the heater assembly can improve the control of vaporization of different compounds in the liquid aerosol-forming substrate. The heater assembly can result in the simultaneous vaporization of a first and second compound of the aerosol-forming substrate at a desired rate. The first compound may be primarily vaporized in either the first or second central region. The second compound may be primarily vaporized in the other of the first or second central region. The heater assembly can result in the vaporization of the first and second compounds of the liquid aerosol-forming substrate in a more favorable ratio. The heater assembly can provide the generation of an aerosol with a more desirable composition. The heater assembly can provide more consistent generation of an aerosol with a more desirable composition. 【0014】 The temperature difference between the first and second central regions of the internal volume may arise from a reduction in the cross-sectional area of ​​the internal volume defined by the heating element. Since the first and second central regions are separated by a gap along the longitudinal axis, the cross-sectional area of ​​the volume of the retaining material in the first central region may differ from the cross-sectional area of ​​the volume of the retaining material in the second central region. Therefore, if the cross-sectional area of ​​the internal volume of the retaining material is smaller, the heating element may be closer to the central region of the retaining material. For example, if the cross-sectional area of ​​the volume of the retaining material in the first central region is smaller than the cross-sectional area of ​​the volume in the second central region, the heating element may be closer to the first central region than to the second central region. 【0015】 Heat may be transferred from the heating element to the holding element by conduction. The temperatures of the first and second central regions may depend on the shortest distance between the heating element and the respective central regions of the holding material. The temperature of each central region of the holding material may increase as the shortest distance to the heating element decreases along the long axis. The temperature difference may be particularly noticeable when the heater assembly is not in thermal equilibrium, for example, after the initial activation of the heating element at the start of smoke extraction. This is because there may be a lag or delay between the initial activation of the heating element to heat the holding material and the central region of the holding element reaching its maximum temperature. The degree of the lag or delay may depend on the thermal conductivity of the holding material. The greater the distance between the heating element and the respective central regions, the longer the lag or delay to reach the maximum temperature. 【0016】 Alternatively, the heating element may be configured to generate an alternating magnetic field, and the holding material may include or be composed of a susceptor. The temperatures of the first and second central regions may depend on the density or strength of the alternating magnetic field. The magnetic flux density or strength of the alternating magnetic field may increase as the cross-sectional area of ​​the internal volume decreases. The magnetic flux density or strength of the alternating magnetic field may increase as the heating element is closer to each central region of the holding material. 【0017】 The vaporized compounds of the aerosol-forming substrate can enter at least one airflow path passing through the first central region and the second central region. This is advantageous in that it can ensure that the vaporized compounds enter directly into the airflow path rather than passing through other regions of the retaining element which may be at different temperatures. The vaporized compounds in at least one airflow path may be mixed or otherwise combined to form an aerosol. 【0018】 The heating element may be in contact with the holding material. The holding material may have a fibrous or spongy structure. The holding material may include capillary material. The holding material may include bundles of capillaries. For example, the holding material may include one or more of fibers, threads, and porous tubes. 【0019】 The retaining material may include a sponge-like or foam-like material. The structure of the retaining material may form a plurality of small holes or tubes through which the liquid can be moved by capillary action. 【0020】 The retaining material may include any suitable material or combination of materials. Suitable materials include, but are not limited to, sponge or foam materials, ceramic or graphite-based materials in the form of fibers or sintered powders, foamable metal or plastic materials, and fibrous materials, such as spun or extruded fibers (cellulose acetate, polyester, or bonded polyolefin, polyethylene, terylene or polypropylene fibers, nylon fibers or ceramics). The retaining material may preferably include ceramics. The retaining material may have any suitable capillary action and porosity so as to be used with liquid aerosol-forming substrates having different physical properties. 【0021】 The heating element may have a helical shape. The longitudinal axis may be defined along the central axis of the helical shape. The cross-sectional area of ​​the internal volume defined by the helical heating element may decrease from the first end of the internal volume to the second end. The first central region of the retaining material may be located toward the first end of the internal volume. The second central region of the retaining material may be located toward the second end of the internal volume. Therefore, during operation, the temperature of the first central region may be lower than the temperature of the second central region. This may have the advantages described above. 【0022】 In a preferred embodiment, the helical shape of the heating element is a helix with a truncated tip. The radius of curvature of the heating element may decrease along the longitudinal axis in the same direction as the cross-sectional area of ​​the internal volume decreases. 【0023】 The heater assembly may include a first heating element and a second heating element. The internal volume of the holding material may be defined between the first heating element and the second heating element. 【0024】 The separation between the first and second heating elements may decrease along the longitudinal axis in the same direction as the decrease in the cross-sectional area of ​​the internal volume. Each of the first and second heating elements may include a series of connected surfaces. These surfaces may be substantially parallel to the longitudinal axis and substantially perpendicular to the longitudinal axis. The first and second heating elements may be arranged such that the separation between their substantially parallel surfaces decreases along the longitudinal axis. Adjacent surfaces may form a step. In other words, a step can be formed by a surface substantially parallel to the longitudinal axis and a surface substantially perpendicular to the longitudinal axis. Each of the first and second heating elements may include a first step and a second step. The separation between heating elements in the first step may be greater than the separation in the second step. The first central portion of the retaining material may be located between the first step of the first and second heating elements. The second central portion of the holding material may be located between the first heating element and the second stage of the second heating element. The first and second heating elements may include further stages; for example, the first and second heating elements may include a third stage. 【0025】 The minimum distance from the first central region to the heating element may be greater than the minimum distance from the second central region to the heating element. 【0026】 The boiling point of the first compound may be between 160°C and 280°C. The boiling point of the first compound may also be approximately 247°C. The first compound may be nicotine. 【0027】 The boiling point of the second compound may be between 210°C and 330°C. The boiling point of the second compound may also be approximately 290°C. The second compound may be glycerol. 【0028】 The internal volume may include a third central region via a gap from the first central region and the second central region along the longitudinal axis. The third central portion may be located on the opposite side of the first central region compared to the second central region. During operation, the third central region may reach a temperature lower than the temperatures of the first central portion and the second central portion. The minimum distance from the third central region to the heating element may be greater than the minimum distance from the first central region to the heating element and greater than the minimum distance from the second central region to the heating element. How providing regions of the internal volume having different temperatures improves the control of the vaporization of the various compounds of the liquid aerosol-forming substrate has already been described, and these compounds have different boiling points. By providing a third central region having a temperature even lower than the first region, the control of vaporization can be further advantageously improved. 【0029】 Furthermore, the aerosol-forming substrate may contain a third compound. The boiling point of the third compound may be lower than the boiling point of the first compound. The boiling point of the third compound may be lower than the boiling point of the second compound. The boiling point of the third compound may be from 100 to 240 °C, preferably from 120 to 220 °C. The boiling point of the third compound is preferably 188 °C. The third compound may be propylene glycol. At the low temperature of the third central region, advantageously, the third compound can be mainly vaporized. By providing such a third central region, the simultaneous vaporization of each of the first compound, the second compound, and the third compound can be ensured. 【0030】 At least one airflow path may pass through a third central region of the internal volume via a gap from the first central region and the second central region along the longitudinal axis. When the aerosol-forming substrate contains a third compound, this may ensure that the vapors of all three compounds enter at least one airflow path for inhalation by the user. 【0031】 The heater assembly may use a resistance heating arrangement. At least one heating element may be a resistance heating element. The heater assembly, in particular the heating elements, may be electrically connected to or configured to be connectable to a current source. The heating elements may contain or be formed from any material having suitable electrical and mechanical properties. 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 alloys include stainless steel, constantan, nickel-containing, cobalt-containing, chromium-containing, aluminum-containing, titanium-containing, zirconium-containing, hafnium-containing, niobium-containing, molybdenum-containing, tantalum-containing, tungsten-containing, tin-containing, gallium-containing, manganese-containing, and iron-containing alloys, as well as nickel, iron, cobalt, stainless steel-based superalloys, Timetal®, iron-aluminum alloys, and iron-manganese-aluminum alloys. Timetal® is a registered trademark of Titanium Metals Corporation. The wire may be coated with one or more electrical insulators. Preferred materials may be 304, 316, 304L, 316L stainless steel, and graphite. 【0032】 In addition, combinations of the above materials may be used. For example, a material with high resistivity may be combined with a material with low resistivity. This may be advantageous if one of the materials is more beneficial in terms of other respects, such as price, machinability, or other physical and chemical parameters. 【0033】 The resistance of at least one heating element may increase along the longitudinal axis in the same direction as the cross-sectional area of ​​the internal volume decreases. During operation, this can advantageously provide a temperature gradient along the length of the heating element. The temperature of the heating element may increase along the longitudinal axis in the same direction as the cross-sectional area of ​​the internal volume decreases. As described above, the first and second central regions of the retaining material are generally heated to different temperatures as a result of the geometric shape of the internal volume defined by the heating element. The temperature gradient along the heating element can increase the temperature difference between the first and second central regions of the retaining material. Therefore, providing a heating element with such a temperature gradient can enable increased control over the vaporization of the first and second compounds. 【0034】 The resistance of a heating element can increase as a result of a decrease in its cross-sectional area. Changing the cross-section, or cross-sectional area, of a heating element can result in different sections of the heating element reaching different temperatures. For example, in a resistance heating element, sections of the heating element with a smaller cross-sectional area may have greater resistance and therefore may resistively heat to higher temperatures. 【0035】 Alternatively, or additionally, this may provide the storage components of the liquid aerosol-forming substrate with regions where the temperature rises at a greater rate and regions where the temperature rises at a lesser rate. As described above, this may lead to the simultaneous vaporization of liquid aerosol-forming substrate compounds having higher and lower boiling points at the desired rates. 【0036】 The heating element may extend between the first end and the second end. For example, the length of the heating element may extend between the first end and the second end. The heating element may have a first cross-sectional area at a first point between the first end and the second end. The heating element may have a first cross-sectional area at a second point between the first point and the second end. For example, the first cross-sectional area may be at least 10, 20, 30, 40, 50, 60, 70, or 80 percent less than the second cross-sectional area. 【0037】 The minimum cross-sectional area along the length of the heating element may be at least 10 percent less than the maximum cross-sectional area along the length of the heating element. The minimum cross-sectional area along the length of the heating element may be at least 20, 40, 60, or 80 percent less than the maximum cross-sectional area along the length of the heating element. 【0038】 The width, thickness, or both of the width and thickness of the heating element may vary along the length of the heating element. 【0039】 Heater assemblies may use induction heating arrangements. The use of induction heating, rather than resistance arrangements, offers improved energy conversion due to power losses associated with resistance heaters, particularly those resulting from contact resistance at the connection between the resistance heater and the power delivery system. To function, resistance heaters are connected to a power source through leads provided within the device or heater assembly, either permanently or replaceably. Even with improved automated manufacturing techniques, resistance heater systems generally have contact resistance in the leads, which generates parasitic losses. Replaceable resistance heater devices can also suffer from the accumulation of film or other materials that increase contact resistance between the replaceable cartridge and the leads. In contrast, induction heating systems do not require contact between the heating element and the leads and are therefore not plagued by the contact resistance problems present in resistance heater devices. 【0040】 At least one heating element may be a susceptor. The heating element acting as a susceptor may be configured to be heated by an alternating magnetic field. The alternating magnetic field may be generated by an aerosol generating system. The alternating magnetic field may also be generated by passing an alternating current through an inductor coil of the aerosol generating system, which surrounds the heater assembly when in use. The alternating current may have any suitable frequency. The alternating current may be a high-frequency alternating current. The alternating current may have a frequency of 100 kilohertz (kHz) to 30 megahertz (MHz). 【0041】 The heat generated by the heating element may be transferred to the holding material. In such cases, the induction heating arrangement may have the advantage of not requiring the formation of electrical contacts between the heating element of the heater assembly and, for example, another component to the power supply of the aerosol generation system. Furthermore, the heater assembly can be manufactured at a lower cost. For example, the heater assembly may be manufactured as part of a cartridge. Cartridges are generally disposable items that are manufactured in much larger quantities than the equipment used for operation. Therefore, even if more expensive equipment is required, the reduced cost of the cartridge can lead to significant cost savings for both manufacturers and consumers. 【0042】 Alternatively, the retaining material may include a susceptor element. The retaining material may consist of a susceptor element. At least one heating element may form or include an inductor coil configured to heat the susceptor element of the retaining material. At least one heating element may be electrically connected to or connectable to a power supply. The power supply may be configured to generate an alternating current. The heating element may be configured to generate an alternating magnetic field. The temperatures of the first and second central regions may depend on the magnetic flux density or strength of the alternating magnetic field. The density or strength of the alternating magnetic field may increase as the cross-sectional area of ​​the internal volume defined by the heating element containing or forming the inductor coil decreases. The magnetic flux density or strength of the alternating magnetic field may increase as the heating element is closer to each central region of the retaining material. Such arrangements may have the advantage that a large temperature gradient is maintained within the internal volume even when the heater assembly reaches thermal equilibrium or maximum temperature. 【0043】 The heater assembly may comprise a first heating element and a second heating element, each of which may include or form an inductor coil. For example, the first and second heating elements may be stepped as described above. The internal volume of the retaining material may be defined between the first and second heating elements. The first heating element may be positioned on the opposite side of the second heating element. Each of the first and second heating elements may include a flat inductor coil. Providing two heating elements, each including an inductor coil, can advantageously increase the magnetic field strength or magnetic flux density. The inductor coils may be arranged to provide an additional magnetic field to each other within their internal volume. Similarly, alternating currents passing through the first and second heating elements may be configured to provide an additional magnetic field to each other within their internal volume. Alternating currents of the same frequency may pass through each of the first and second heating elements. The alternating currents may be supplied by the same power source. 【0044】 At least one airflow path may be defined through the retaining material and include an airflow path passing through a first central region and a second central region in a direction parallel to the longitudinal axis. The airflow path may be arranged so that, during use, air enters the retaining material from the end having the largest cross-sectional area. In other words, the air may first pass through the cooler of the first or second central region. When the heater assembly is operating, the incoming air may be considerably cooler than the retaining material. Therefore, the air entering the retaining material can advantageously cool each central region. When the air reaches the other of the first or second central region, the air may have been heated by the heater assembly, and thus its cooling effect may be reduced. Therefore, such an arrangement of the airflow path can advantageously increase the temperature difference between the first and second central regions. 【0045】 Alternatively, at least one airflow path may include a first airflow path defined through a retaining material passing through a first central region in a direction perpendicular to the longitudinal axis. At least one airflow path may include a second airflow path defined through a retaining material passing through a second central region in a direction perpendicular to the longitudinal axis. 【0046】 The heater assembly may include a storage section for storing the aerosol-forming substrate. The heater assembly may include a storage section for the aerosol-forming substrate. The storage section may be configured to supply the aerosol-forming substrate to the retaining material. The storage section may be configured to supply the aerosol-forming substrate to the retaining material at the location where the internal volume filled by the retaining material has the largest cross-sectional area. During use, this can advantageously increase the temperature difference between the first and second central regions of the internal volume, as the aerosol-forming substrate in the storage section may be at a lower temperature than the aerosol-forming substrate in the retaining material. 【0047】 The retaining material may store or be configured to store the aerosol-forming substrate. The retaining material may be in fluid communication with the storage section. 【0048】 The storage unit may comprise a storage unit housing containing an aerosol-forming substrate. The channel may be defined through the housing. At least one airflow channel may pass through this channel. 【0049】 The present disclosure also provides an aerosol generating system comprising the heater assembly described above. The aerosol generating system may further include a power supply connectable to the heater assembly. The aerosol generating system may further include a controller for controlling the power supplied from the power supply to the heater assembly. Thus, the controller can control the heating of the heating element. 【0050】 The power source may be a battery. The power source may be configured to supply power to a heating element, which may be for the purpose of heating the heating element. 【0051】 The power supply may be configured to supply power to the heating element in order to resistively heat it. The aerosol generation system may include an inductor coil. 【0052】 The power supply for the aerosol generating system may be configured to supply an alternating current to an inductor coil when at least one heating element of the heater assembly forms or includes an inductor coil. The power supply for the aerosol generating system may be configured to supply an oscillating current to an inductor coil when at least one heating element of the heater assembly forms or includes an inductor coil. The oscillating current may be a high-frequency oscillating current. As used herein, a high-frequency oscillating current means an oscillating current having a frequency of 100 kHz to 10 MHz. 【0053】 The aerosol generating system may include a cartridge, which comprises a cartridge housing including a heater assembly. The cartridge may be configured to engage with an aerosol generator. The power supply may be configured to supply power to the heating element only when the cartridge is engaged with the aerosol generator. 【0054】 The cartridge may have an air intake. The cartridge may have an air outlet. The air intake may be in fluid communication with the air outlet. The heating element may be located downstream of the air intake. The heating element may be located upstream of the air outlet. 【0055】 The cartridge may have a first electrical contact and a second electrical contact electrically connected to the heating element. The electrical contact may include one or more of the following: tin, silver, gold, copper, aluminum, steel such as stainless steel, phosphor bronze, tin alloyed with antimony, tin alloyed with zirconium, tin alloyed with bismuth, or tin alloyed with other components that improve resistance to organic acids. 【0056】 The electrical contacts may be configured to form an electrical connection with the corresponding electrical contacts on the aerosol generator when the cartridge engages with the aerosol generator. 【0057】 The storage section, as optionally described in relation to the heater assembly, may instead form part of the cartridge. The heater assembly, and in particular the retaining material of the heater assembly, may be in fluid communication with the storage section. 【0058】 The aerosol generation system may further include an aerosol generator. The cartridge may be removably receptacleable in the aerosol generator. 【0059】 The aerosol generator may include a device housing that includes a power supply and a controller. 【0060】 The aerosol generating system may further include a mouthpiece that is in fluid communication with at least one airflow path, allowing the user to draw air through at least one airflow path. The cartridge may also include a mouthpiece. When the cartridge is engaged with the aerosol generating device during use, the user can inhale through the mouthpiece of the cartridge. This allows air to flow through the air intake, then across, through, or after the heater assembly or heating element, and then through the air outlet. 【0061】 The aerosol generating system may be a handheld aerosol generating system. The aerosol generating system may be an electrically heated smoking system. 【0062】 According to this disclosure, a cartridge for use in the aerosol generating system described above is also provided, and the cartridge includes the heater assembly described above. 【0063】 The present disclosure also provides a method for using an aerosol generating system, the aerosol generating system comprising: a retaining material containing an aerosol-forming substrate in a condensed form, wherein the aerosol-forming substrate comprises a first compound and a second compound, the second compound having a higher boiling point than the first compound; at least one airflow path defined through the retaining material; a heater assembly comprising at least one heating element shaped to define an internal volume, the internal volume being filled with the retaining material; a power supply; and a controller for controlling the power supplied from the power supply to the heater assembly, the internal volume having a cross-sectional area decreasing along the longitudinal axis, the at least one airflow path passing through a first central region of the internal volume and a second central region of the internal volume, the first central region and the second central region being separated by a gap along the longitudinal axis, the method comprising activating the at least one heating element to heat the retaining material such that the first central region is heated to a different temperature from the second central region. 【0064】 The step of activating at least one heating element may include heating the first central region to a temperature lower than the temperature of the second central region. 【0065】 The step of activating at least one heating element may include heating the first central region to a temperature at least 20°C lower than the temperature of the second central region. 【0066】 The step of activating at least one heating element may include heating a first central region of the internal volume to a temperature of 160–280°C. 【0067】 The step of activating at least one heating element may include heating a second central region of the internal volume to a temperature of 210–330°C. 【0068】 The step of activating at least one heating element may include heating an aerosol-forming substrate so that vapor is generated that enters at least one airflow path. 【0069】 The vapor entering the portion of at least one airflow path passing through the first central region of the internal volume contains the first compound in a higher weight than the second compound. 【0070】 The vapor entering the portion of at least one airflow path passing through the second central region of the internal volume contains the second compound in a higher weight than the first compound. 【0071】 As used herein, the term “aerosol” refers to the dispersion of solid particles or droplets, or a combination of solid particles and droplets, in a gas. Aerosols may be visible or invisible. Aerosols may include not only vapors of substances that are normally liquid or solid at room temperature, but also solid particles or liquid droplets, or a combination of solid particles and liquid droplets. 【0072】 As used herein, the term “aerosol-forming substrate” refers to a substrate having the ability to release volatile compounds that can form aerosols. The volatile compounds may be released by heating or burning the aerosol-forming substrate. 【0073】 The aerosol-forming substrate may contain multiple compounds. These multiple compounds may have different boiling points. For example, the aerosol-forming substrate may contain a first compound having a first boiling point at atmospheric pressure, and a second compound having a second boiling point at atmospheric pressure, where the first boiling point is higher than the second. The aerosol-forming substrate may also contain a third compound having a third boiling point at atmospheric pressure. 【0074】 The aerosol-forming substrate may include an aerosol-forming compound. As used herein, “aerosol-forming compound” refers to any suitable compound or mixture of compounds that facilitates the formation of a stable aerosol that, when used, is substantially resistant to thermal decomposition at, for example, the operating temperature of the system. Suitable aerosol-forming compounds 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). 【0075】 The aerosol-forming substrate may contain nicotine. The aerosol-forming substrate may contain water. The aerosol-forming substrate may also contain glycerol, which has a higher boiling point than nicotine. The aerosol-forming substrate may contain propylene glycol. The aerosol-forming substrate may contain plant-derived materials. The aerosol-forming substrate may contain homogenized plant-derived materials. The aerosol-forming substrate may contain tobacco. The aerosol-forming substrate may contain tobacco-containing materials. The tobacco-containing materials may contain volatile tobacco-flavoring compounds. These compounds may be released from the aerosol-forming substrate upon heating. The aerosol-forming substrate may contain homogenized tobacco materials. The aerosol-forming substrate may contain other additives and components such as flavoring agents. 【0076】 As used herein, the term “liquid aerosol-forming substrate” refers to an aerosol-forming substrate in a condensed form. Therefore, the “liquid aerosol-forming substrate” may be one or more of a liquid, gel, or paste, or may contain one or more of these. If the liquid aerosol-forming substrate is a gel or paste, or contains a gel or paste, the gel or paste may liquefy upon heating. For example, a gel or paste may liquefy when heated to a temperature below 50, 75, 100, 150, or 200°C. 【0077】 As used herein, the term “heating element” includes both elements configured to rise in temperature themselves when power is supplied, and elements configured to cause a temperature rise in a coupled component when power is supplied, such as an inductor coil coupled to a susceptor element. 【0078】 As used herein, “susceptor element” refers to a conductive element that heats up when subjected to a fluctuating magnetic field. This may be the result of eddy currents and / or hysteresis losses induced in the susceptor element. Possible materials for susceptor elements include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, and virtually any other conductive element. Advantageously, susceptor elements are ferrite elements. The material and geometric shape for a susceptor element can be selected to provide the desired electrical resistance and heat generation. 【0079】 A non-exclusive list of non-limiting embodiments is provided below. One or more features of these embodiments may be combined with any one or more features of other embodiments, forms, or aspects described herein. [Examples] 【0080】 [Example 1] A heater assembly for use in an aerosol generation system, wherein the heater assembly is A retaining material containing a condensed aerosol-forming substrate, wherein the aerosol-forming substrate comprises a first compound and a second compound, and the second compound has a higher boiling point than the first compound; At least one airflow path defined through the retaining material, A heating element comprising at least one heating element shaped to define an internal volume, wherein the internal volume is filled with a retaining material, The internal volume has a cross-sectional area that decreases along the longitudinal axis, A heater assembly in which at least one airflow path passes through a first central region and a second central region of the internal volume, with the first and second central regions separated by a gap along the longitudinal axis. 【0081】 [Example 2] A heater assembly according to Example 1, comprising a heating element having a spiral shape. 【0082】 [Example 3] The heater assembly described in Example 2, wherein the spiral shape of the heating element is a spiral with the tip cut off. 【0083】 [Example 4] A heater assembly according to Example 2 or Example 3, wherein the radius of curvature of the heating element decreases along the longitudinal axis in the same direction as the cross-sectional area of ​​the internal volume decreases. 【0084】 [Example 5] A heater assembly according to Example 1, comprising a first heating element and a second heating element. 【0085】 [Example 6] The heater assembly according to Example 5, wherein the internal volume of the holding material is defined between the first heating element and the second heating element. 【0086】 [Example 7] A heater assembly according to Example 5 or Example 6, wherein the separation between the first heating element and the second heating element decreases along the longitudinal axis in the same direction as the decrease in the cross-sectional area of ​​the internal volume. 【0087】 [Example 8] A heater assembly according to any one of Examples 1 to 7, wherein the minimum distance from the first central region to the heating element is greater than the minimum distance from the second central region to the heating element. 【0088】 [Example 9] A heater assembly according to any one of Examples 1 to 8, wherein the boiling point of the first compound is 160 to 280 degrees. 【0089】 [Example 10] A heater assembly according to any of Examples 1 to 9, wherein the boiling point of the second compound is 210 to 330 degrees. 【0090】 [Example 11] A heater assembly according to any one of Examples 1 to 10, wherein the aerosol-forming substrate contains a third compound. 【0091】 [Example 12] The heater assembly described in Example 11, wherein the boiling point of the third compound is 120 to 220 degrees. 【0092】 [Example 13] A heater assembly according to Example 11 or Example 12, wherein at least one airflow path passes through a gap from a first central region and a second central region along the longitudinal axis to a third central region of the internal volume. 【0093】 [Example 14] The heater assembly according to Example 13, wherein the third central region is located on the opposite side of the first central region compared to the second central region. 【0094】 [Example 15] A heater assembly according to Example 13 or Example 14, wherein the minimum distance from the third central region to the heating element is greater than the minimum distance from the first central region to the heating element and greater than the minimum distance from the second central region to the heating element. 【0095】 [Example 16] A heater assembly according to any one of Examples 1 to 15, wherein at least one of the heating elements is a resistance heating element. 【0096】 [Example 17] A heater assembly according to any one of Examples 1 to 16, wherein the resistance of at least one heating element increases along the longitudinal axis in the same direction as the cross-sectional area of ​​the internal volume decreases. 【0097】 [Example 18] The heater assembly according to Example 17, wherein the resistance of the heating element increases as a result of a decrease in the cross-sectional area of ​​the heating element. 【0098】 [Example 19] A heater assembly according to any one of Examples 1 to 17, wherein at least one heating element is a susceptor. 【0099】 [Example 20] A heater assembly according to any one of Examples 1 to 17, wherein the holding material includes a susceptor element, and at least one heating element forms or includes an inductor coil configured to heat the susceptor element of the holding material. 【0100】 [Example 21] The heater assembly according to Example 20, comprising a first heating element and a second heating element, wherein each of the first and second heating elements includes or forms an inductor coil. 【0101】 [Example 22] A heater assembly according to any one of Examples 1 to 21, wherein at least one airflow path is defined through a retaining material and includes an airflow path passing through a first central region and a second central region in a direction parallel to the longitudinal axis. 【0102】 [Example 23] A heater assembly according to any one of Examples 1 to 21, comprising a first airflow path defined through a retaining material, wherein at least one airflow path passes through a first central region in a direction perpendicular to the longitudinal axis. 【0103】 [Example 24] The heater assembly according to Example 23, comprising a second airflow path defined through a retaining material, wherein at least one airflow path passes through a second central region in a direction perpendicular to the longitudinal axis. 【0104】 [Example 25] A heater assembly according to any of Examples 1 to 24, wherein the holding material is formed of ceramic. 【0105】 [Example 26] An aerosol generating system comprising a heater assembly described in any one of Examples 1 to 25. 【0106】 [Example 27] A power supply that can be connected to the heater assembly, The aerosol generating system according to Example 26, further comprising a controller for controlling the power supplied from the power source to the heater assembly. 【0107】 [Example 28] The aerosol generating system according to Example 27, wherein the power supply for the aerosol generating system is configured to supply a high-frequency oscillating current to an inductor coil when at least one heating element of the heater assembly forms or includes an inductor coil. 【0108】 [Example 29] An aerosol generating system according to any one of Examples 26 to 28, wherein the aerosol generating system comprises a cartridge, and the cartridge comprises a cartridge housing including a heater assembly. 【0109】 [Example 30] The aerosol generating system according to Example 29, wherein the aerosol generating system further comprises an aerosol generating device, and a cartridge is removably receptacleable into the aerosol generating device. 【0110】 [Example 31] The aerosol generating system according to Example 30, wherein the aerosol generating device comprises a device housing including a power supply and a controller. 【0111】 [Example 32] An aerosol generating system according to any one of Examples 26 to 31, further comprising a mouthpiece communicating with at least one airflow path and fluid, enabling a user to draw air through at least one airflow path. 【0112】 [Example 33] The aerosol generating system is a handheld aerosol generating system, as described in any one of Examples 26 to 32. 【0113】 [Example 34] The aerosol generating system according to any one of Examples 26 to 33, wherein the aerosol generating system is an electrically heated smoking system. 【0114】 [Example 35] A cartridge for use in an aerosol generating system, comprising a heater assembly defined in any one of Examples 1 to 25. 【0115】 [Example 36] A method using an aerosol generating system, wherein the aerosol generating system is A retaining material containing a condensed aerosol-forming substrate, wherein the aerosol-forming substrate comprises a first compound and a second compound, the second compound having a higher boiling point than the first compound, At least one airflow path defined through the retaining material, A heater assembly comprising at least one heating element shaped to define an internal volume, wherein the internal volume is filled with a retaining material, Power supply and It includes a controller for controlling the power supplied from the power source to the heater assembly, The internal volume has a cross-sectional area that decreases along the longitudinal axis, At least one airflow path passes through a first central region of the internal volume and a second central region of the internal volume, and the first and second central regions are separated by a gap along the longitudinal axis. A method comprising activating at least one heating element to heat a holding material such that a first central region is heated to a different temperature than a second central region. 【0116】 [Example 37] A method using the aerosol generating system according to Example 36, wherein the step of activating at least one heating element includes heating a first central region to a temperature lower than the temperature of a second central region. 【0117】 [Example 38] A method using the aerosol generating system according to Example 36 or Example 37, wherein the step of activating at least one heating element includes heating a first central region to a temperature at least 20°C lower than the temperature of a second central region. 【0118】 [Example 39] A method using the aerosol generating system described in Example 38, wherein the step of activating at least one heating element includes heating a first central region of the internal volume to a temperature of 160-280°C. 【0119】 [Example 40] A method using the aerosol generating system according to any one of Examples 36 to 39, wherein the step of activating at least one heating element includes heating a second central region of the internal volume to a temperature of 2410 to 330°C. 【0120】 [Example 41] A method using the aerosol generating system according to any one of Examples 36 to 40, wherein the step of activating at least one heating element includes heating an aerosol-forming substrate so that vapor is generated that enters at least one airflow path. 【0121】 [Example 42] A method using the aerosol generating system described in Example 41, wherein the vapor entering a portion of at least one airflow path passing through a first central region of the internal volume contains the first compound in a higher weight than the second compound. 【0122】 [Example 43] A method using the aerosol generating system described in Example 41 or Example 42, wherein the vapor entering a portion of at least one airflow path passing through a second central region of the internal volume contains the second compound in a higher weight than the first compound. 【0123】 Features described in reference to one embodiment or example may also be applicable to other embodiments and examples. 【0124】 Here, we will further describe the embodiments with reference to the figures. [Brief explanation of the drawing] 【0125】 [Figure 1] Figure 1 shows a schematic cross-sectional view of the first aerosol generation system, which includes a cartridge incorporating the first heater assembly. [Figure 2] Figure 2 shows a perspective view of the first heater assembly shown in Figure 1. [Figure 3] Figure 3 shows a schematic cross-sectional view of the first heater assembly shown in Figure 1, separate from the aerosol generation system. [Figure 4] Figure 4 shows a perspective view of the second heater assembly, separate from the aerosol generation system. [Figure 5] Figure 5 shows a schematic cross-sectional view of the second heater assembly shown in Figure 4. [Figure 6] Figure 6 shows a schematic cross-sectional view of a third heater assembly, which is similar to the first heater assembly in Figure 1 but has a different airflow path configuration. [Figure 7] Figure 7 shows a schematic cross-sectional view of a fourth heater assembly, which is similar to the first heater assembly in Figure 1, but has a cross-sectional area that decreases along the length of the heating element. [Figure 8] Figure 8 shows a schematic cross-sectional view of the second aerosol generation system. [Figure 9]Figure 9 shows a fifth heater assembly containing two heating elements, each of which includes an inductor coil. 【0126】 Figure 1 shows a cross-sectional view of the first aerosol generating system 100. The aerosol generating system 100 comprises an aerosol generator 150 and a cartridge 200. In this embodiment, the aerosol generating system 100 is an electrically operated smoking system. 【0127】 The aerosol generator 150 is portable and has a size comparable to a conventional cigar or cigarette. The device 150 comprises a battery 152, such as a lithium iron phosphate battery, and a controller 154 electrically connected to the battery 152. The device 150 also comprises two electrical contacts 156, 158 electrically connected to the battery 152. This electrical connection is a wired connection and is not shown in Figure 1. In Figure 1, the aerosol generator 150 is engaged with a cartridge 200. In this embodiment, the cartridge 200 engages with the aerosol generator 150 via threads 206 of the cartridge 200 that are mated with corresponding threads 162 of the aerosol generator 150. 【0128】 The cartridge 200 comprises a first electrical contact 214 and a second electrical contact 216, an air intake 202, an air outlet 204, and a first heater assembly 300. The air intake 202 is in fluid communication with the air outlet 204. The heater assembly 300 is positioned downstream of the air intake 202 and upstream of the air outlet 204. The heater assembly 300 includes a retaining material 302 that is in fluid communication with a storage section 303 of a liquid aerosol forming substrate. The storage section 303 is described herein as a separate component from the heater assembly 300. However, in some embodiments, the storage section 300 forms part of the heater assembly. The heater assembly 300 also comprises a helical heating element 304. The first electrical contact 214 and the second electrical contact 216 are electrically connected to the heating element 304. The airflow path 306 is defined through the center of the retaining material 302. 【0129】 In this system 100, the liquid aerosol-forming substrate contains approximately 74% by weight of glycerin, 24% by weight of propylene glycol, and 2% by weight of nicotine, but any suitable substrate can be used. At atmospheric pressure, nicotine has a boiling point of approximately 247°C, glycerin has a boiling point of approximately 290°C, and propylene glycol has a boiling point of approximately 188°C. Therefore, when this liquid aerosol-forming substrate is first heated to form an aerosol, some systems may undesirably evaporate a disproportionately large amount of propylene glycol (which has the lowest boiling point of the compounds forming the substrate). This can result in the delivery of undesirable aerosols to the user, such as an aerosol containing less nicotine than desired. This can also undesirably change the relative proportions of the compounds in the substrate over a longer period of time. The present invention can eliminate or at least reduce these undesirable effects. 【0130】 During use, the user inhales smoke from the air outlet 204 of the cartridge 200. Simultaneously, the user presses a button (not shown) on the aerosol generator 150. Pressing this button sends a signal to the controller 154, which in turn supplies power from the battery 152 to the heating element 304 via the device's electrical contacts 156, 158 and the cartridge's electrical contacts 214, 216. This causes current to flow through the heating element 304, thereby resistively heating it. In other embodiments, an airflow sensor or pressure sensor is located inside the cartridge 200 and electrically connected to the controller 154. The airflow sensor or pressure sensor detects that the user is inhaling smoke from the air outlet 204 of the cartridge 200 and sends a signal to the controller 154 to supply power to the heating element 304. Thus, in these embodiments, the user does not need to press a button to heat the heating element 304. 【0131】 As the user inhales smoke from the air outlet 204 of the cartridge 200, air is drawn into the air intake 202. This air then moves towards the air outlet 204 through the channel 313 defined through the storage section 303 and then through the airflow path 306 defined through the retaining material 306. This airflow encompasses vapor formed by the heating element 304 heating the liquid aerosol-forming substrate in the storage component 302 of the liquid aerosol-forming substrate. This encompassed vapor is then cooled and condensed to form an aerosol. This aerosol is then delivered to the user through the air outlet 204. As the liquid aerosol-forming substrate in the retaining material 302 is heated, vaporized, and encompassed by the airflow, liquid aerosol-forming substrate from the storage section 303 moves into the retaining material 302. This liquid aerosol-forming substrate from the storage section 303 effectively replaces the vaporized liquid aerosol-forming substrate. The liquid aerosol-forming substrate from the storage section 303 can be drawn into the retaining material 302, at least partially, by capillary action. This is because the storage component 302 of the liquid aerosol-forming substrate is a capillary material having a fibrous structure. In this embodiment, the retaining material 302 is a capillary material having a fibrous structure. In the embodiment shown in Figure 1, the capillary material is formed from polyester, but any suitable material can be used. 【0132】 The heater assembly is shown more clearly in Figures 2 and 3, with the heater assembly 300 shown separately from the rest of the aerosol generation system. 【0133】 Figure 2 shows a perspective view of the heater assembly 300, which illustrates how the heating element 304 is helical and has a truncated helical shape. The helical shape of the heating element 304 defines the internal volume filled with the retaining material 302. The cross-sectional area of ​​the internal volume decreases along the major axis defined through the center of the helical shape. The retaining material 302 filling the internal volume has a truncated conical shape. The heating element 304 is a piece of material. In this embodiment, the material is stainless steel, but any suitable material can be used. 【0134】 The heating element 304 has a uniform cross-sectional area along its length, as well as uniform thickness and width along its length. The heating element 304 has uniform resistance along its length. Therefore, when in use and when power is supplied to the heating element 304, the heating force of the heating element 304 is substantially constant along its length. However, due to the geometric shape of the internal volume defined by the heating element 304, the center of the retaining material contains a higher temperature region and a lower temperature region. This is clearly shown in Figure 3. 【0135】 Figure 3 shows a cross-sectional view of the heater assembly 300. The three central regions of the internal volume, filled with the retaining material 302, are shown by dotted lines. The three central regions are separated by gaps along the longitudinal axis. The first central region 312 is located between the second central region 310 and the third central region 308. The second central region 310 is located toward the first end of the longitudinal axis where the cross-sectional area of ​​the internal volume is smallest. The third central region 308 is located toward the second end of the longitudinal axis where the cross-sectional area of ​​the internal volume is largest. During use, the air passing through the airflow path 306 passes sequentially through the third central region 308, the first central region 312, and the second central region 310. 【0136】 As described above, the cross-sectional area of ​​the internal volume of the retaining material 302 decreases along the longitudinal axis. Since heat is transferred from the heating element to the retaining element by conduction, the temperatures of the first and second central regions depend on the shortest distance between the heating element and the respective central regions of the retaining material. When the cross-sectional area of ​​the volume of the retaining material is smaller, the heating element 304 is closer to the center of the retaining material. As shown in Figure 3, the second central region 310, which is closer to the heating element 304 than the first central region 312, is similarly closer to the heating element 304 than the third central region 308. This results in uneven heating of the retaining material filling the internal volume, with the third central region 308 heating to a lower temperature than the first central region 312, and similarly heating to a lower temperature than the second central region 310. 【0137】 The temperature differences between the first central region 312, the second central region 310, and the third central region 308 result in the vapor generated in the first central region 312 containing different weight ratios of nicotine compared to the vapor generated in the second central region 310 and the third central region 308. Similarly, the vapor generated in the first central region contains different weight ratios of glycerol and propylene glycol compared to the second and third central regions. In particular, propylene glycol, which has the lowest boiling point, is vaporized in the coldest third central region; nicotine, which has a higher boiling point than propylene glycol, is vaporized mainly in the intermediate first central region 312; and glycerol, which has the highest boiling point, is vaporized in the hottest second central region 310. 【0138】 The temperature difference between the central regions of the retaining material 302 is particularly pronounced when the heater assembly is not in thermal equilibrium, for example, after the initial activation of the heating element. This is because there is a lag or delay between the initial activation of the heating element to heat the retaining material and the central region of the retaining element reaching its maximum temperature. The degree of this lag or delay depends on the thermal conductivity of the retaining material. The greater the distance between the heating element and each central region, the longer the lag or delay before reaching the maximum temperature. 【0139】 The airflow path 306 passes through the first central region 312, the second central region 310, and the third central region 308 in a direction parallel to the longitudinal axis. The airflow path 306 may be configured such that, during use, air enters the airflow path from the end of the retaining material 302 having the largest cross-sectional area. In other words, it passes through the third central region 308 first. During operation, the third central region 308 is the coldest. When the heater assembly is operating, the incoming air is considerably colder than the retaining material 302. Therefore, the air entering the airflow path may advantageously act to cool the third central region. By the time the air reaches the first central region 312 and the second central region 310, the air is heated by the heater assembly, and thus the cooling effect of the air is reduced. Therefore, this configuration of the airflow path 306 increases the temperature difference between the third central region, the first central region, and the second central region. 【0140】 Figures 4 and 5 show a second heater assembly 400 including a first heating element 404 and a second heating element 405. Figure 4 shows a perspective view of the second heater assembly 400, and Figure 5 shows a cross-sectional view. Both the first heating element 404 and the second heating element 405 are stepped and include three steps configured such that the heating elements gradually move closer together. This is most clearly shown in Figure 5. Between the first heating element 404 and the second heating element 405, an internal volume filled with retaining material 402 is defined. The cross-sectional area of ​​the internal volume decreases along the longitudinal axis as a result of the stepped heating elements. The longitudinal axis is defined through the center of the internal volume. Both the first heating element 404 and the second heating element 405 are fragments of a shaped material. In this embodiment, the material is stainless steel, but any suitable material may be used. 【0141】 Figure 5 shows the three central regions of the internal volume defined by the heating elements 404 and 405. The three central regions are shown by dashed lines. The three central regions are separated by gaps along the longitudinal axis. The first central region 412 is located between the second central region 410 and the third central region 408. The second central region 410 is located toward the first end of the longitudinal axis where the cross-sectional area of ​​the internal volume is smallest. The third central region 408 is located toward the second end of the longitudinal axis where the cross-sectional area of ​​the internal volume is largest. During use, air passing through the airflow path 406 passes through the third central region 408, the first central region 412, and the second central region 410 in sequence. During use, air passing through the airflow path 306 passes through the third central region 408, the first central region 412, and the second central region 410 in sequence. 【0142】 Therefore, similar to the first heater assembly, the second heater assembly provides an arrangement in which the first central portion, the second central portion, and the third central portion are oriented in different directions. 【0143】 Figure 6 shows a third heater assembly 500. The third heater assembly 500 has two airflow paths 506, 507, rather than a single airflow path as shown in the first and second heater assemblies. The internal volume defined by the heating element 304 is filled with retaining material 502. The first airflow path 506 is defined through a first central region 508 of the internal volume. The second airflow path 507 is defined through a second central region 510 of the internal volume. Naturally, the internal volume includes the area between the first region 508 and the central region 510, and other central regions on either side. However, Figure 6 does not show the airflow paths defined through these central regions. In some embodiments, the heater assembly 500 may include additional airflow paths passing through different central regions of the retaining material. 【0144】 In all other respects, the third heater assembly 500 is identical to the first heater assembly 300. 【0145】 Figure 7 shows the fourth heater assembly. The fourth heater assembly 600 includes a helical heating element 604. The helical heating element differs from the heating element 304 of the first heater assembly in that the width of the heating element decreases along the longitudinal axis in the same direction as the cross-sectional area of ​​the internal volume decreases. In all other respects, the fourth heater assembly 600 is identical to the first heater assembly 300. 【0146】 The resistance of the heating element 604 increases as its width decreases. Therefore, during use, the heating element becomes hotter along its length. This increases the temperature difference between the first central region and the second central region. Thus, providing a heating element with such a temperature gradient allows for increased control over the vaporization of the first and second compounds. 【0147】 Figure 8 shows a schematic cross-sectional view of the second aerosol generating system 800. The aerosol generating system 800 comprises an aerosol generator 850 and a cartridge 900 incorporating the second heater assembly 700. In this embodiment, the aerosol generating system 800 is an electrically operated smoking system. 【0148】 The aerosol generator 850 is portable and has a size comparable to a conventional cigar or cigarette. The device 850 includes a battery 852, such as a lithium iron phosphate battery, and a controller 854 electrically connected to the battery 852. The device 850 also includes an induction coil 856 electrically connected to the battery 852. The device 850 also includes an air intake 858 and an air outlet 860 that is in fluid communication with the air intake 858. 【0149】 The cartridge 900 comprises an air intake 902, an air outlet 904, and a second heater assembly 700. The air intake 902 is in fluid communication with the air outlet 904. The heater assembly 700 is positioned downstream of the air intake 902 and upstream of the air outlet 904. As shown in Figure 8, when the cartridge 500 engages with the aerosol generator 850, the air outlet 860 of the device 850 is adjacent to the air intake 802 of the cartridge 900. Therefore, when in use, if the user inhales smoke from the air outlet 904 of the cartridge 900, the air passes through the air intake 858 of the device 850, then through the air outlet 860 of the device 850, then through the air intake 902 of the cartridge 900, then through the heater assembly 700, and then out of the air outlet 904 of the cartridge 900. 【0150】 In this system 800, the liquid aerosol-forming substrate contains approximately 98% by weight of glycerin and 2% by weight of nicotine, but any suitable substrate can be used. At atmospheric pressure, nicotine has a boiling point of approximately 247°C and glycerin has a boiling point of approximately 290°C. Therefore, when this liquid aerosol-forming substrate is first heated to form an aerosol, some systems may undesirably evaporate a disproportionately large amount of nicotine (which has the lowest boiling point of the compounds forming the substrate). This can lead to the delivery of an undesirable aerosol to the user. This can also undesirably change the relative proportion of the compounds in the substrate over a longer period of time. The present invention can eliminate or at least reduce these undesirable effects. 【0151】 In Figure 8, the aerosol generator 900 is engaged with the cartridge 850. In this embodiment, the cartridge 900 engages with the aerosol generator 850 via openings 906, 908 that form snap-fit ​​connections with corresponding protrusions 862, 864 on the aerosol generator 850. 【0152】 The heater assembly 700 includes a helical heating element 704 and a retaining material 702 that fills the internal volume defined by the helical heating element. This is a similar arrangement to the first heater assembly 300 described in relation to Figure 1. The heating element 704 includes a piece of susceptor material. In this embodiment, the susceptor material is aluminum, but any suitable susceptor material may be used. 【0153】 The retaining material 702 in this embodiment is a capillary material having a fibrous structure. The capillary material is formed from polyester, but any suitable material may be used. 【0154】 During use, the user inhales smoke from the air outlet 704 of the cartridge 900. Simultaneously, the user presses a button (not shown) on the aerosol generator 850. Pressing this button sends a signal to the controller 854, which in turn causes the battery 852 to supply a high-frequency current to the induction coil 856. This causes the induction coil 856 to generate a fluctuating electromagnetic field. The heating element 704 is positioned within this magnetic field. Thus, this fluctuating electromagnetic field generates eddy currents and hysteresis losses within the heating element 704. Consequently, the heating element 704 is inductively heated. In other embodiments, an airflow sensor or pressure sensor is located within the device 850 and electrically connected to the controller 854. The airflow sensor or pressure sensor detects that the user is inhaling smoke from the air outlet 904 of the cartridge 900 and sends a signal to the controller 854, which supplies a high-frequency current to the induction coil 856, thereby heating the heating element 904. Therefore, in these embodiments, the user does not need to press a button to heat the heating element 704. 【0155】 When the heating element 704 is heated, higher temperature regions and lower temperature regions are created in the holding material 702. The creation of these higher and lower temperature regions causes the compounds of the liquid aerosol-forming substrate in the holding material 602, which have higher and lower boiling points, to vaporize simultaneously. This effect is described above in relation to the aerosol generation system shown in Figure 1. 【0156】 When a user inhales smoke from the air outlet 904 of cartridge 900, air is drawn into the air intake port 858. This air then moves towards the air outlet 904 through the channel 813 defined through the storage section 803 and then through the airflow path 806 defined through the retaining material 702. This airflow entrains vapor formed by the heating of the liquid aerosol-forming substrate in the retaining material 703. This entrained vapor is then cooled and condensed to form an aerosol. Next, this air moves towards the air outlet 904. This airflow entrains vapor formed by the heating of the liquid aerosol-forming substrate by the heating element 704. This entrained vapor is then cooled and condensed to form an aerosol. This aerosol is then delivered to the user via the air outlet 904. 【0157】 Figure 9 shows a sixth heater assembly 1000 using an alternative induction heating mechanism. The sixth heater assembly 1000 includes a first heating element 1004 and a second heating element 1005. Both the first heating element 1004 and the second heating element 1005 include an electrically insulated substrate made of polyamide. The electrically insulated substrate has a stepped shape including three steps. The steps are configured so that the heating elements progressively move closer together. Each heating element 1004, 1005 includes an induction coil 1008 in the form of a flat helical on each of the steps. The induction coil 1008 is mounted or embedded in the electrically insulated substrate. 【0158】 An internal volume filled with retaining material 1002 is defined between the first heating element 1004 and the second heating element 1005. The cross-sectional area of ​​the internal volume decreases along the longitudinal axis as a result of the stepped heating element. The longitudinal axis is defined through the center of the internal volume. The airflow path 1006 is defined parallel to the longitudinal axis and through the center of the retaining material. This is a similar arrangement to that shown in Figures 4 and 5. However, in this embodiment, an inductor coil 1008 in the shape of a flat helical coil is formed on each of the heating elements. 【0159】 Furthermore, the holding material 1006 consists of a susceptor material. In this embodiment, the susceptor material is made of foamed metal, but any suitable material can be used. The heating element, including the induction coil, is connected to the battery of the aerosol generation system. This is not shown in Figure 9. 【0160】 During use, a signal is sent to the controller of the aerosol generation system, and as a result, a high-frequency current is supplied from the battery to the induction coils 1008 of the heating elements 1004 and 1005. This causes the induction coils 1008 to generate a fluctuating electromagnetic field. The holding material 1006, made of susceptor material, is positioned within this magnetic field. Therefore, this fluctuating electromagnetic field generates eddy currents and hysteresis losses within the holding material 1002. Consequently, the holding material 1002 is inductively heated. 【0161】 The temperature of the retaining material 1002 depends on the magnetic flux density or magnetic field strength of the alternating magnetic field. The magnetic flux density between the induction coils increases as the induction coils move closer together. Therefore, as described in relation to previous embodiments, the retaining material is heated to different temperatures in different zones, corresponding to different stages of the heating elements 1004 and 1005. The first central region of the retaining material 1006 is heated to a different temperature than the second or third central region, which is not shown in Figure 9. 【0162】 Figure 10 shows a schematic cross-sectional view of the seventh heater assembly 1100. The seventh heater assembly 1100 includes a first heating element 1104 and a second heating element 1105. Similar to the heater assembly 1000 in Figure 9, both the first heating element 1004 and the second heating element 1005 include electrically insulated substrates made of polyamide. The electrically insulated substrates of both the first heating element 1104 and the second heating element 1105 are stepped and include three steps configured such that the heating elements move progressively closer together. Each heating element 1104, 1105 includes an induction coil (not shown in Figure 10) in the form of a flat helical on each of the steps. 【0163】 An internal volume filled with retaining material 1102 is defined between the first heating element 1004 and the second heating element 1005. The cross-sectional area of ​​the internal volume decreases along the longitudinal axis as a result of the stepped heating element. The longitudinal axis is defined through the center of the internal volume. The airflow path 1006 is defined parallel to the longitudinal axis and through the center of the retaining material 1102. This is a similar arrangement to that shown in Figure 9. However, in the embodiment shown in Figure 10, the retaining material does not consist of susceptor material. Instead, the susceptor material is provided in the form of a cylindrical mesh 1103 surrounding the airflow path 1106. 【0164】 During use, a signal is sent to the controller of the aerosol generation system (not shown in Figure 10), and as a result, high-frequency current is supplied from the battery to the induction coils of the heating elements 1004 and 1005. This causes the induction coil 1008 to generate a fluctuating electromagnetic field. The holding material 1002, made of susceptor material, is positioned within this magnetic field. Therefore, this fluctuating electromagnetic field generates eddy currents and hysteresis losses within the cylindrical mesh 1103. Consequently, the cylindrical mesh 1103 is inductively heated, and the heat is conducted to the holding material 1102, heating the aerosol-forming substrate contained within the holding material 1102. 【0165】 The temperature of the holding material 1106 depends on the magnetic flux density or magnetic field strength of the alternating magnetic field. The magnetic flux density between the inductor coils increases as the inductor coils move closer together. Therefore, as described in relation to previous embodiments, the holding material is heated to different temperatures in different central regions 1108, 1110, and 1112, corresponding to different stages of the heating elements 1104 and 1105.

Claims

[Claim 1] A heater assembly for use in an aerosol generating system, wherein the heater assembly is A retaining material containing a condensed aerosol-forming substrate, wherein the aerosol-forming substrate comprises a first compound and a second compound, and the second compound has a higher boiling point than the first compound; At least one airflow path defined through the aforementioned holding material, The invention comprises at least one heating element shaped to define an internal volume, wherein the internal volume is filled with the holding material, The internal volume has a cross-sectional area that decreases along the longitudinal axis, The at least one airflow path passes through a first central region of the internal volume and a second central region of the internal volume, and the first central region and the second central region are separated by a gap along the longitudinal axis. A heater assembly wherein the resistance of at least one of the heating elements increases along the longitudinal axis in the same direction as the cross-sectional area of ​​the internal volume decreases. [Claim 2] The heater assembly according to claim 1, comprising a heating element having a spiral shape. [Claim 3] The heater assembly according to claim 1, comprising a first heating element and a second heating element, wherein the internal volume is defined between the first heating element and the second heating element. [Claim 4] The heater assembly according to claim 3, wherein the separation between the first heating element and the second heating element decreases along the longitudinal axis in the same direction as the decrease in the cross-sectional area of ​​the internal volume. [Claim 5] The heater assembly according to any one of claims 1 to 4, wherein the minimum distance from the first central region to the heating element is greater than the minimum distance from the second central region to the heating element. [Claim 6] The heater assembly according to any one of claims 1 to 5, wherein at least one of the heating elements is a resistance heating element. [Claim 7] The heater assembly according to any one of claims 1 to 5, wherein at least one of the heating elements is a susceptor. [Claim 8] The heater assembly according to any one of claims 1 to 7, wherein the at least one airflow path includes a first airflow path defined through the retaining material, passing through the first central region in a direction perpendicular to the longitudinal axis. [Claim 9] An aerosol generating system comprising a heater assembly according to any one of claims 1 to 8. [Claim 10] A power supply that can be connected to the aforementioned heater assembly, The aerosol generating system according to claim 9, further comprising a controller for controlling the power supplied from the power source to the heater assembly. [Claim 11] The aerosol generating system according to claim 9 or 10, wherein the aerosol generating system further comprises an aerosol generating device, and a cartridge is removably receivable in the aerosol generating device. [Claim 12] A cartridge for use in an aerosol generating system, comprising a heater assembly as defined in any one of claims 1 to 8. [Claim 13] A method using an aerosol generating system, wherein the aerosol generating system is A retaining material containing a condensed aerosol-forming substrate, wherein the aerosol-forming substrate comprises a first compound and a second compound, and the second compound has a higher boiling point than the first compound; At least one airflow path defined through the aforementioned holding material, A heater assembly comprising at least one heating element shaped to define an internal volume, wherein the internal volume is filled with the retaining material, Power supply and The system includes a controller for controlling the power supplied from the power source to the heater assembly, The internal volume has a cross-sectional area that decreases along the longitudinal axis, The at least one airflow path passes through a first central region of the internal volume and a second central region of the internal volume, and the first central region and the second central region are separated by a gap along the longitudinal axis. The resistance of the at least one heating element increases along the longitudinal axis in the same direction as the cross-sectional area of ​​the internal volume decreases. A method comprising activating at least one heating element to heat the holding material such that the first central region is heated to a different temperature from the second central region.

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