Heater assembly for an aerosol generating system

Abstract

A heater assembly for an aerosol generating system is provided, the aerosol generating system comprising a liquid storage portion for containing a liquid aerosol-forming substrate. The heater assembly comprises an electric heater (30) having at least one heating element (36) for heating the liquid aerosol-forming substrate to form an aerosol, and a capillary body (22) for conveying the liquid aerosol-forming substrate from the liquid storage portion of the aerosol generating system to the at least one heating element. The at least one heating element is formed of an electrically conductive material deposited directly on a porous outer surface (32) of the capillary body. A cartridge (20) for an aerosol generating system and a method for manufacturing such a cartridge are also provided.

Description

[0001] This application is a divisional application of an international application filed on June 15, 2016, with international application number PCT / EP2016 / 063807, national application number 201680035452.0, and entitled “Heater assembly for an aerosol generating system”, which has entered the Chinese national phase. Technical Field

[0002] The present invention relates to aerosol-generating systems and heater assemblies for aerosol-generating systems, the heater assemblies comprising an electric heater adapted to vaporize an aerosol-forming substrate. In particular, the present invention relates to handheld aerosol-generating systems, such as electrically operated smoking systems. Aspects of the present invention relate to heater assemblies for aerosol-generating systems, cartridges for aerosol-generating systems, and methods for manufacturing those cartridges. Background Art

[0003] One type of aerosol generating system is an electrically operated smoking system. Handheld electrically operated smoking systems are known that consist of a device portion that includes a battery and control electronics, and a box portion that includes a supply of aerosol-forming substrate and an electrically operated vaporizer. A box that includes a supply of aerosol-forming substrate and a vaporizer is sometimes referred to as a "cartomiser". The vaporizer is typically a heater assembly. In some known examples, the aerosol-forming substrate is a liquid aerosol-forming substrate, and the vaporizer includes a coil of heating wire wrapped around an elongated core soaked in the liquid aerosol-forming substrate. The box portion typically includes not only a supply of aerosol-forming substrate and an electrically operated heater assembly, but also a mouthpiece that a user sucks on to draw the aerosol into their mouth during use.

[0004] Therefore, an electrically operated smoking system that vaporizes an aerosol-forming liquid by heating to form an aerosol generally comprises a wire coil wrapped around a capillary material that holds the liquid. The electric current passing through the wire causes the resistance heating of the wire, thereby vaporizing the liquid in the capillary material. The capillary material is generally kept in the airflow path so that air is drawn through the wick and carries the vapor. The vapor is subsequently cooled to form an aerosol.

[0005] This type of system can be effective for generating aerosols, but can be challenging to manufacture in a cost-effective and reproducible manner. Furthermore, the core and coil assembly, along with the associated electrical connections, can be fragile and difficult to handle.

[0006] It is desirable to provide a heater assembly for an aerosol generating system, such as a handheld electrically operated smoking system, with improved aerosol characteristics. It is also desirable to provide a more robust heater assembly for an aerosol generating system, and to provide a cartridge for an aerosol generating system with improved aerosol characteristics. Summary of the Invention

[0007] According to a first aspect of the present invention, there is provided a heater assembly for an aerosol generating system, the aerosol generating system having a liquid storage portion for accommodating a liquid aerosol-forming substrate, the heater assembly comprising: an electric heater having at least one heating element for heating the liquid aerosol-forming substrate to form an aerosol; and a capillary body for conveying the liquid aerosol-forming substrate from the liquid storage portion of the aerosol generating system to the at least one heating element, wherein the at least one heating element is formed of an electrically conductive material deposited directly onto the porous outer surface of the capillary body.

[0008] Advantageously, by depositing the conductive material directly onto the porous outer surface of the capillary body to form the at least one heating element, the contact between the at least one heating element and the capillary body can be improved. For example, this can compensate for surface roughness or unevenness on the outer surface of the capillary body. This can reduce the number or severity of "hot spots" on the outer surface of the capillary body, which might otherwise occur if the heating element were not in contact with the capillary body along its length, and thus lead to improved aerosol properties. The improved contact between the at least one heating element and the capillary body can also allow for improved transfer of the liquid aerosol-forming substrate to the heating element.

[0009] Additionally, the heating element is formed by depositing the conductive material directly onto the porous outer surface of the capillary body, to which it is adhered. This reduces the risk of loss of contact between the heating element and the capillary body, for example, due to deformation of the heating element during assembly or thermal stresses induced during use. It also allows the use of heater geometries or layouts that might not otherwise be possible. For example, more complex heating element geometries or layouts, or those using finer filaments, than would be possible using preformed electric heaters.

[0010] As used herein, the term "capillary body" refers to a component of a heater assembly that is capable of transporting a liquid aerosol-forming substrate to an electric heater by capillary action.

[0011] As used herein, the term "conductive material" means a material having a 1×10 -2 Materials with a resistivity of Ωm or less.

[0012] As used herein, the term "deposition" refers to application, for example in the form of a liquid, plasma or vapor, as a coating on the outer surface of the capillary body, which subsequently condenses or aggregates to form the heating element, rather than simply laid down on the capillary body as a solid preformed part.

[0013] As used herein, the term "direct deposition" refers to deposition of the conductive material onto the porous outer surface of the capillary body such that the at least one heating element is in direct contact with the porous outer surface.

[0014] As used herein, the term "porous" means formed of a material that is permeable to and allows migration of the liquid aerosol-forming substrate therethrough.

[0015] In certain preferred embodiments, the electrically conductive material of the at least one heating element is at least partially diffused into the porous outer surface of the capillary body.

[0016] As used herein, the term "diffusion into the porous outer surface" means that the conductive material becomes embedded in or intermixed with the material of the porous outer surface at the interface between the conductive material and the capillary body, such as by extending into pores of the porous outer surface.

[0017] With this arrangement, the contact between the at least one heating element and the capillary body can be further improved, resulting in a further reduction in the number or severity of "hot spots" on the outer surface of the capillary body and improved aerosol properties. Furthermore, by extending into the porous outer surface of the capillary body, the contact area between the at least one heating element and the capillary body is increased. This can result in further improved transport of the liquid aerosol-forming substrate through the capillary body to the heating element, and in improved heating of the liquid aerosol-forming substrate by the heating element. Adhesion between the heating element and the capillary body can also be improved, thereby further reducing the risk of loss of contact between the heating element and the capillary body, for example due to deformation of the heating element during assembly or due to thermal stresses induced during use.

[0018] The conductive material from which the at least one heating element is formed can be deposited on the porous outer surface in any suitable manner. For example, the conductive material can be deposited as a liquid onto the porous outer surface of the capillary body using a dispensing pipette or syringe or using a fine-tip transfer device such as a needle.

[0019] In some embodiments, at least one heating element comprises a printable conductive material printed onto the porous outer surface of the capillary body. In such embodiments, any suitable known printing technique may be used. For example, one or more of screen printing, gravure printing, flexographic printing, and inkjet printing may be used. Such printing processes may be particularly suitable for high-speed production processes.

[0020] Alternatively, the electrically conductive material from which the at least one heating element is formed may be deposited onto the porous outer surface of the capillary body by one or more vacuum deposition processes, such as evaporative deposition and sputtering.

[0021] The at least one heating element may be formed of any suitable electrically conductive material. In certain preferred embodiments, the electrically conductive material comprises one or more of a metal, an electrically conductive polymer, and an electrically conductive ceramic.

[0022] Suitable conductive metals include aluminum, silver, nickel, gold, platinum, copper, tungsten, and alloys thereof. In some embodiments, the conductive material comprises metal powder suspended in a glue such as epoxy. In one embodiment, the conductive material comprises silver-containing epoxy.

[0023] Suitable conductive polymers include PEDOT (poly(3,4-ethylenedioxythiophene)), PSS (poly(p-phenylene sulfide)), PEDOT:PSS (a mixture of PEDOT and PSS), PANI (polyaniline), PPY (poly(pyrrole)), PPV (poly(p-phenylene vinylene)), or any combination thereof.

[0024] Suitable conductive ceramics include ITO (indium tin oxide), SLT (lanthanum-doped strontium titanate), SYT (yttrium-doped strontium titanate), or any combination thereof.

[0025] The conductive material may further include one or more additives selected from the group consisting of a solvent, a curing agent, an adhesion promoter, a surfactant, a viscosity reducer, and an aggregation inhibitor. For example, such additives may be used to aid deposition of the conductive material onto the porous outer surface of the capillary body, to increase diffusion of the conductive material into the porous outer surface of the capillary body, to reduce the time required for the conductive material to solidify, to improve adhesion between the conductive material and the capillary body, or to reduce the amount of aggregation of suspended particles (such as metal particles or powder) in the conductive material prior to application to the porous outer surface of the capillary body.

[0026] The heating profile of the electric heater may be substantially constant across the porous outer surface of the capillary body.

[0027] In some embodiments, at least one heating element is arranged such that its temperature profile varies across the electric heater.

[0028] Advantageously, by varying the temperature profile of the at least one heating element, the heat generated by the electric heater on the outer surface of the capillary body may be adjusted to the characteristics of the cartridge, for example to the air flow characteristics of the cartridge.

[0029] In certain preferred embodiments, at least one heating element is arranged so that the electric heater generates more heat toward the periphery of the porous outer surface. This allows the electric heater to compensate for heat losses from the periphery of the outer surface, such as heat losses due to heat conduction, thereby resulting in a more uniform temperature across the porous outer surface.

[0030] By varying the distribution of at least one heating element across the porous outer surface, the heating distribution of the electric heater can be varied. For example, by increasing the distribution density of the at least one heating element toward the center of the porous outer surface, the heating distribution of the electric heater can be increased toward the center of the porous outer surface. As used herein, the term "distribution density" refers to the proportion of the porous outer surface on which the conductive material of the at least one heating element is deposited. For example, a distribution density of 50% in a particular region of the porous outer surface would indicate that the conductive material is deposited on 50% of that region, but not on the remaining 50% of that region.

[0031] By varying the resistance of the heating element across the porous outer surface, the heating profile of the electric heater can be varied across the porous outer surface.

[0032] In some embodiments, the electrical resistance of at least one heating element decreases toward the center of the porous outer surface to change the distribution of heat generated by the electric heater on the porous outer surface. With this arrangement, the electric heater generates more heat toward the periphery of the porous outer surface of the capillary body. This can allow the electric heater to compensate for heat losses at the periphery of the outer surface of the capillary body, such as heat losses due to thermal conduction, thereby resulting in a more uniform temperature across the porous outer surface of the capillary body.

[0033] By using multiple heating elements formed from conductive materials having different resistivity values, the resistance of at least one heating element can be varied. For example, by arranging the multiple heating elements on the porous outer surface, the resistance of the at least one heating element can be reduced toward the center of the porous outer surface, such that the resistivity of at least one of the heating elements toward the periphery of the porous outer surface of the capillary body is greater than the resistivity of at least one of the heating elements toward the center of the porous outer surface of the capillary body.

[0034] In some embodiments, the cross-sectional area of ​​at least one heating element changes. This allows the temperature distribution of at least one heating element to be adjusted according to the characteristics of the box, because the resistance of at least one heating element is inversely proportional to its cross-sectional area. In such embodiments, at least one heating element can include a heating element with a cross-sectional area that changes along the length of the heating element. Alternatively or additionally, at least one heating element can include a first heating element with a first cross-sectional area and a second heating element with a second cross-sectional area, wherein the second cross-sectional area is different from the first cross-sectional area.

[0035] In certain preferred embodiments, the cross-sectional area of ​​the at least one heating element increases toward the center of the porous outer surface. This results in more heat being generated from the at least one heating element toward the periphery of the porous outer surface. This allows the electric heater to compensate for heat losses at the periphery of the outer surface, such as heat losses due to heat conduction, thereby resulting in a more uniform temperature across the porous outer surface.

[0036] By varying the thickness of the at least one heating element or the width of the at least one heating element or the thickness and width of the at least one heating element, the cross-sectional area of ​​the at least one heating element may be varied.

[0037] As used herein, the terms "varies", "different" and "different" refer to deviations beyond standard manufacturing tolerances, particularly values ​​that deviate from each other by at least 5%.

[0038] As used herein, the term "thickness" refers to the dimension of the heating element in a direction perpendicular to the porous outer surface of the capillary body and perpendicular to the length of the heating element.

[0039] As used herein, the term "width" refers to the dimension of the heating element in a direction parallel to the porous outer surface of the capillary body and perpendicular to the length of the heating element.

[0040] In any of the above embodiments, adjacent portions of at least one heating element can be spaced apart to define a plurality of holes in the electric heater, wherein the holes are of different sizes to vary the temperature distribution of the electric heater. In such embodiments, the at least one heating element can include a plurality of heating elements that are spaced apart to define a plurality of holes. Alternatively or additionally, the at least one heating element can include one or more heating elements that form a nonlinear shape such that adjacent portions of the one or more heating elements are spaced apart to define a plurality of holes.

[0041] In certain preferred embodiments, the pore size is smaller towards the periphery of the porous surface of the capillary body.

[0042] This can result in more heat being generated from the at least one heating element toward the periphery of the porous outer surface. This allows the electric heater to compensate for heat losses from the periphery of the outer surface, such as heat losses due to thermal conduction, thereby resulting in a more uniform temperature across the porous outer surface. This arrangement also enables more aerosol to pass through the electric heater in the central portion of the porous outer surface and can be advantageous in heater assemblies where the center of the porous surface is the most important vaporization region. For example, the average size of the pores in the peripheral portion of the porous outer surface of the capillary body is at least 10% smaller, preferably at least 20% smaller, and more preferably at least 30% smaller than the average size of the pores outside the peripheral portion of the porous outer surface of the capillary body. The area of ​​the peripheral portion can be less than about 80% of the total area of ​​the porous outer surface of the capillary body, preferably less than about 60%, more preferably less than about 40%, and most preferably less than about 20%.

[0043] The electric heater can include a single heating element. Alternatively, the electric heater can include a plurality of heating elements connected in series or in parallel. In such embodiments, the plurality of heating elements can be formed by the same conductive material.

[0044] Alternatively, the electric heater may include at least one first heating element formed of a first conductive material and at least one second heating element formed of a second conductive material, the second conductive material being different from the first conductive material, the first conductive material and the second conductive material being deposited directly on the porous outer surface of the capillary body. Preferably, the resistivity of the first conductive material is different from the resistivity of the second conductive material.

[0045] Advantageously, this allows adjusting the temperature profile of the at least one heating element, and thus the amount of heat generated by the electric heater on the outer surface of the capillary body, according to desired characteristics.

[0046] In certain preferred embodiments, the electric heater comprises a plurality of heating elements formed of conductive materials having different resistivity values. In such embodiments, the plurality of heating elements can be arranged so that the resistivity of at least one of the heating elements toward the periphery of the porous outer surface of the capillary body is greater than the resistivity of at least one of the heating elements toward the center of the porous outer surface of the capillary body. Utilize this arrangement, the electric heater generates more heat toward the periphery of the porous outer surface of the capillary body. This allows the electric heater to compensate for heat losses at the periphery of the outer surface of the capillary body, such as heat losses caused by heat conduction, thereby causing the temperature on the porous outer surface of the capillary body to be more uniform.

[0047] The electric heater may include a plurality of heating elements formed from a plurality of different electrically conductive materials. In some embodiments, the electric heater includes a plurality of heating elements, each heating element being formed from a different electrically conductive material.

[0048] One or more of the heating elements can be formed from a material whose electrical resistance varies significantly with temperature, such as an iron-aluminum alloy. This allows the temperature or changes in temperature to be determined using resistance measurements of the heating element. This can be used in puff detection systems and for control purposes.

[0049] The electric heater may include a first conductive contact portion and a second conductive contact portion in electrical contact with the at least one heating element. In such embodiments, the first conductive contact portion and the second conductive contact portion may be formed from a conductive material deposited directly on the porous outer surface of the capillary body.

[0050] In some embodiments, substantially the entire electric heater is formed from one or more electrically conductive materials deposited directly on the porous outer surface of the capillary body.

[0051] The resistance of the electric heater is preferably between 0.3 ohms and 4 ohms. More preferably, the resistance of the electric heater is between 0.5 ohms and 3 ohms, and more preferably about 1 ohm.

[0052] Where the electric heater comprises an electrically conductive contact portion for contacting at least one heating element, the electrical resistance of the at least one heating element is preferably at least one order of magnitude greater than the electrical resistance of the contact portion, and more preferably at least two orders of magnitude greater. This ensures that the heat generated by passing current through the electric heater is localized to the at least one heating element. If the cartridge is to be used with a battery-powered aerosol generating system, it is generally advantageous for the electric heater to have a low overall electrical resistance. It is also desirable to minimize parasitic losses between the electrical contacts and the heating element to minimize parasitic power losses. A low-resistance, high-current system allows high power to be delivered to the electric heater. This allows the heater to quickly heat the heating element to the desired temperature.

[0053] The conductive contact portion may be fixed directly to the at least one heating element. Alternatively, the conductive contact portion may be integral with the at least one heating element. Providing a conductive contact portion integral with the at least one heating element allows the electric heater to be reliably and simply connected to a power source.

[0054] The capillary body can be a capillary wick or other types or shapes of capillary bodies, such as capillaries. In a preferred embodiment, the capillary body comprises a capillary material. The capillary material can comprise any suitable material or combination of materials. The capillary body can comprise a single capillary material.

[0055] In some embodiments, the capillary body comprises a first capillary material and a second capillary material, wherein the at least one heating element is formed by a conductive material deposited directly on the porous outer surface of the first capillary material, and wherein the second capillary material is in contact with the first capillary material and is separated from the electric heater by the first capillary material, and the first capillary material has a higher thermal decomposition temperature than the second capillary material. The first capillary material effectively serves as a spacer separating the at least one heating element from the second capillary material so that the second capillary material is not exposed to a temperature higher than its thermal decomposition temperature. In some embodiments, the thermal decomposition temperature of the first capillary material is at least 160 degrees Celsius, and preferably at least 250 degrees Celsius.

[0056] As used herein, "thermal decomposition temperature" refers to the temperature at which a material begins to decompose and lose mass by producing gaseous byproducts.

[0057] Advantageously, the second capillary material can occupy a larger volume than the first capillary material and can accommodate more aerosol-forming substrate than the first capillary material. The second capillary material can have a wicking performance that is superior to the first capillary material. The second capillary material can be cheaper or have a higher filling capacity than the first capillary material. The second capillary material can be polypropylene.

[0058] The first capillary material may separate the electric heater from the second capillary material by a distance of at least 1.5 mm, and preferably, between 1.5 mm and 2 mm, in order to provide a sufficient temperature drop across the first capillary material.

[0059] When the capillary body includes a capillary material, the capillary material can have a fibrous or spongy structure. The capillary material preferably includes a capillary bundle. For example, the capillary material can include multiple fibers or threads or other fine-pore tubes. The fibers or threads can be roughly aligned to transport the liquid to the heater. Alternatively, the capillary material can include a spongy or foamy material. The structure of the capillary material forms multiple small holes or tubes, through which the liquid can be transported by capillary action. One or more capillary materials can include any suitable material or combination of materials. Examples of suitable materials are sponge or foam materials, ceramic or graphite-based materials in the form of fibers or sintered powders, foamed metal or plastic materials, fibrous materials, for example, made from spun or extruded fibers such as cellulose acetate, polyester or bonded polyolefins, polyethylene, polyester or polypropylene fibers, nylon fibers, or ceramics. The capillary material can have any suitable capillary action and porosity to accommodate different liquid physical properties. The liquid has physical properties, including but not limited to viscosity, surface tension, density, thermal conductivity, boiling point, and vapor pressure, which allow the liquid to be transported through the capillary device by capillary action.

[0060] According to a second aspect of the present invention, there is provided a cartridge for an aerosol generating system, the cartridge comprising a liquid storage portion for containing a liquid aerosol-forming substrate; and a heater assembly according to any one of the above embodiments.

[0061] In alternative embodiments, the heater assembly may be provided as an integral part of the aerosol generating system, rather than forming part of a cartridge for the aerosol generating system.

[0062] The liquid storage part of box can be provided by capillary body.For example, capillary body can be made by the high retention force capillary material of the liquid storage part that forms box.Alternatively, liquid storage part and capillary body can be the different parts of box.

[0063] In certain embodiments, where the liquid storage portion and the capillary body are distinct components of the cartridge, the capillary body comprises a first end extending into the liquid storage portion for contact with the liquid therein and a porous second end opposite the first end, wherein the at least one heating element is formed of a conductive material deposited directly on the second end of the capillary body. Alternatively, the first end of the capillary body may be external to the liquid storage portion, and the capillary body may comprise at least one other porous surface for contacting the liquid in the liquid storage portion. For example, the capillary body may comprise one or more porous sidewalls of the capillary body for contacting the liquid in the liquid storage portion, and via the porous sidewalls, the liquid aerosol-forming substrate is transferred from the liquid storage portion to the electric heater.

[0064] The liquid storage portion may comprise a housing for containing the liquid aerosol-forming substrate, the housing having an opening, wherein the capillary body is arranged such that the electric heater extends through the opening.

[0065] The cartridge may include a liquid storage portion comprising a housing for containing a liquid aerosol-forming substrate, the housing having an opening. The housing may be a rigid housing and fluid-tight. As used herein, "rigid housing" refers to a self-supporting housing. The capillary body may be a capillary material contained within the housing of the storage portion.

[0066] The housing may contain two or more different capillary materials, wherein a first capillary material in contact with at least one heating element has a higher thermal decomposition temperature, and a second capillary material in contact with the first capillary material but not in contact with at least one heating element has a lower thermal decomposition temperature. The first capillary material effectively serves as a spacer separating the heating element from the second capillary material, so that the second capillary material is not exposed to temperatures higher than its thermal decomposition temperature. As used herein, "thermal decomposition temperature" refers to the temperature at which a material begins to decompose and lose mass by producing gaseous byproducts. Advantageously, the second capillary material can occupy a larger volume than the first capillary material and can accommodate more aerosol-forming substrate than the first capillary material. The second capillary material can have wicking properties that are superior to the first capillary material. The second capillary material can be cheaper or have a higher filling capacity than the first capillary material. The second capillary material can be polypropylene.

[0067] In the case where the liquid storage portion comprises a housing having an opening, the at least one heating element may extend across the entire length dimension of the housing opening. The width dimension is a dimension perpendicular to the length dimension in the plane of the opening. Preferably, the width of the at least one heating element is less than the width of the housing opening. Preferably, the electric heater is spaced from the periphery of the opening. The width of the at least one heating element may be less than the width of the opening in at least one region of the opening. The width of the at least one heating element may be less than 90% of the width of the housing opening, for example, less than 50%, for example, less than 30%, for example, less than 25%. The area of ​​the at least one heating element may be less than 90% of the area of ​​the housing opening, for example, less than 50%, for example, less than 30%, for example, less than 25%. The area of ​​the at least one heating element may be, for example, between 10% and 50% of the opening area, preferably between 15% and 25% of the opening area. The ratio of the opening area of ​​the at least one heating element, i.e., the area of ​​the aperture to the total area of ​​the electric heater, is preferably between about 25% and about 56%. The opening may have any suitable shape. For example, the opening may have a circular, square, or rectangular shape. The area of ​​the opening can be relatively small, preferably less than or equal to about 25 square millimeters. The spacing between the heating element and the perimeter of the opening is preferably sized so that thermal contact is significantly reduced. The spacing between the heating element and the perimeter of the opening can be between 25 microns and 40 microns.

[0068] The at least one heating element is preferably arranged in such a way that the area of ​​physical contact with the liquid storage portion is reduced compared to a situation where the heating element of the electric heater is in contact around the entire periphery of the liquid storage portion. The at least one heating element preferably does not directly contact the periphery of the liquid storage portion. In this way, thermal contact with the liquid storage portion is reduced, and heat loss to the liquid storage portion and other adjacent components (such as those of the aerosol generating system in which the cartridge is used) is reduced.

[0069] Without wishing to be bound by any particular theory, it is believed that by separating the heating element from the liquid storage portion, less heat is transferred to the liquid storage portion, thereby increasing heating efficiency and thereby increasing aerosol generation.

[0070] The electric heater may include a single heating element, or a plurality of heating elements connected in parallel or in series. Where the electric heater includes at least a first conductive contact portion and a second conductive contact portion for contacting at least one heating element, the first conductive contact portion and the second conductive contact portion may be arranged such that the first contact portion contacts the first heating element and the second contact portion contacts the last heating element in the series connection. Additional contact portions may be provided to allow all heating elements to be connected in series.

[0071] If the electric heater includes multiple heating elements, the heating elements can be arranged substantially parallel to one another in space. Preferably, the heating elements are spaced apart from one another. Without wishing to be bound by any particular theory, it is believed that spacing the heating elements apart can provide more efficient heating. For example, by appropriately spacing the heating elements, more uniform heating can be achieved across the area of ​​the opening, compared to, for example, using a single heating element of the same area.

[0072] In the case of an electric heater comprising multiple heating elements, at least one of the multiple heating elements may comprise a first material, and at least another of the multiple heating elements may comprise a second material different from the first material. This may be advantageous for electrical or mechanical reasons. For example, one or more of the heating elements may be formed from a material whose electrical resistance varies significantly with temperature, such as an iron-aluminum alloy. This allows the temperature or temperature change to be determined using resistance measurements of the heating elements. This can be used in a puff detection system to control the heater temperature to maintain it within a desired temperature range.

[0073] At least one heating element may include an array of conductive filaments extending along the length of at least one heating element, with a plurality of holes defined by the spaces between the conductive filaments. In such embodiments, the size of the plurality of holes may be changed by increasing or decreasing the size of the gaps between adjacent filaments. This may be achieved by changing the width of the conductive filaments, or by changing the spacing between adjacent filaments, or by changing the width of the conductive filaments and the spacing between adjacent filaments.

[0074] As used herein, the term "filament" refers to an electrical path disposed between two electrical contacts. The filament can be arbitrarily bifurcated and divided into several paths or filaments, or can be converged into one path from several electrical paths. The filament can have a cross-section that is circular, square, flat, or any other form. In a preferred embodiment, the filament has a substantially flat cross-section. The filament can be arranged in a straight line or a curved manner.

[0075] The conductive filaments may be substantially flat.

[0076] As used herein, "substantially flat" preferably means formed in a single plane and, for example, not wrapped or otherwise conformed to fit a curved or other non-planar shape. A flat electric heater can be easily handled during manufacturing and provides a robust structure.

[0077] A liquid aerosol-forming substrate is a liquid substrate that is capable of releasing volatile compounds that can form an aerosol. The volatile compounds can be released by heating the aerosol-forming substrate.

[0078] The aerosol-forming substrate is a liquid. The aerosol-forming substrate may include a plant-based material. The aerosol-forming substrate may include tobacco. The aerosol-forming substrate may include a tobacco-containing material containing volatile tobacco flavor compounds that are released from the aerosol-forming substrate upon heating. Alternatively, the aerosol-forming substrate may include a tobacco-free material. The aerosol-forming substrate may include a homogenized plant-based material. The aerosol-forming substrate may include a homogenized tobacco material. The aerosol-forming substrate may include at least one aerosol-forming agent. An aerosol-forming agent is any suitable known compound or mixture of compounds that, during use, facilitates the formation of a dense and stable aerosol and is substantially resistant to thermal degradation at the operating temperature of the system. Suitable aerosol-forming agents are well known in the art and include, but are not limited to, polyols such as triethylene glycol, 1,3-butanediol, and glycerol; esters of polyols such as mono-, di-, or tri-glycerides; and aliphatic esters of mono-, di-, or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Preferred aerosol formers are polyols or mixtures thereof, such as triethylene glycol, 1,3-butylene glycol, and most preferably glycerol.The aerosol-forming substrate may include other additives and ingredients, such as fragrances.

[0079] According to a third aspect of the invention, there is provided an aerosol generating system comprising: an aerosol generating device; and a cartridge according to any of the above embodiments, wherein the cartridge is removably coupled to the aerosol generating device, and wherein the aerosol generating device comprises a power supply for the electric heater.

[0080] As used herein, a cartridge being "removably coupled" to a device means that the cartridge and device can be coupled to and decoupled from one another without damaging the device or the cartridge.

[0081] The cartridge can be replaced after consumption. Since the cartridge houses the aerosol-forming substrate and the electric heater, the electric heater is also replaced regularly so that optimal vaporization conditions are maintained even after prolonged use of the main unit.

[0082] The aerosol generating system may further include circuitry connected to the electric heater and a power source, the circuitry being configured to monitor the resistance of the electric heater and control power to the electric heater from the power source based on the monitored resistance. For example, the circuitry may be configured to monitor the resistance of one or more heating elements. By monitoring the temperature of the electric heater, the system can prevent the electric heater from overheating or underheating and ensure optimal vaporization conditions.

[0083] The circuitry may include a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application specific integrated circuit (ASIC), or other circuitry capable of providing control. The circuitry may include additional electronic components. The circuitry may be configured to regulate power to the heater. Power may be supplied to the electric heater continuously after system startup, or may be supplied intermittently, such as on a puff-by-puff basis. Power may be supplied to the electric heater in the form of current pulses.

[0084] The aerosol-generating device includes a power source for the cartridge's electric heater. The power source may be a battery within the device, such as a lithium iron phosphate battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging and may have a capacity that allows for storing sufficient energy for one or more smoking experiences. For example, the power source may have sufficient capacity to allow for continuous aerosol generation for approximately six minutes, corresponding to the typical duration of a conventional cigarette puff, or a multiple of six minutes. In another example, the power source may have sufficient capacity to allow for a predetermined number of puffs or discrete activations of the heater.

[0085] The liquid storage portion may be positioned on a first side of the electric heater, and the airflow channel is located on an opposite side of the electric heater to the storage portion, such that airflow through the electric heater entrains the vaporised aerosol-forming substrate.

[0086] The system can be an electrically operated smoking system. The system can be a handheld aerosol generating system. The aerosol generating system can have dimensions comparable to a conventional cigar or cigarette. The smoking system can have an overall length of about 30 mm to about 150 mm. The smoking system can have an outer diameter of about 5 mm to about 30 mm.

[0087] According to a fourth aspect of the present invention, there is provided a method for manufacturing a box for an aerosol generating system, the method comprising the following steps: providing a liquid storage portion for accommodating a liquid aerosol-forming substrate; providing a capillary body having a porous outer surface; forming an electric heating element by depositing a conductive material directly onto the porous outer surface of the capillary body; filling the liquid storage portion with the liquid aerosol-forming substrate; and connecting the capillary body to the liquid storage portion so that the liquid aerosol-forming substrate contained in the liquid storage portion is transferred from the liquid storage portion to the electric heating element through the capillary body.

[0088] The liquid storage part of box can be provided by capillary body.For example, capillary body can be made by the high retention force capillary material of the liquid storage part that forms box.Alternatively, liquid storage part and capillary body can be the different parts of box.

[0089] In certain embodiments, where the liquid storage portion and the capillary body are distinct components of the cartridge, the capillary body comprises a first end extending into the liquid storage portion for contact with the liquid therein and a porous second end opposite the first end, wherein the at least one heating element is formed of a conductive material deposited directly on the second end of the capillary body. Alternatively, the first end of the capillary body may be external to the liquid storage portion, and the capillary body may comprise at least one other porous surface for contacting the liquid in the liquid storage portion. For example, the capillary body may comprise one or more porous sidewalls of the capillary body for contacting the liquid in the liquid storage portion, and via the porous sidewalls, the liquid aerosol-forming substrate is transferred from the liquid storage portion to the electric heater.

[0090] The liquid storage portion may comprise a housing for containing the liquid aerosol-forming substrate, the housing having an opening, wherein the capillary body is arranged such that the electric heater extends through the opening.

[0091] The conductive material from which the at least one heating element is formed can be deposited on the porous outer surface in any suitable manner. For example, the conductive material can be deposited onto the porous outer surface of the capillary body in the form of a liquid using a dispensing pipette or syringe or using a fine-tipped transfer device such as a needle. In certain embodiments, the conductive material is deposited directly onto the porous outer surface of the capillary body by one or more vacuum deposition methods (such as evaporative deposition and sputtering).

[0092] In a preferred embodiment, the conductive material is deposited by printing a printable conductive material directly onto the porous outer surface of the capillary body. In such embodiments, any suitable known printing technique may be used. For example, one or more of screen printing, gravure printing, flexographic printing, and inkjet printing may be used. Such printing techniques may be particularly advantageous when used in high-speed production processes.

[0093] The printable conductive material may include any suitable conductive material. In certain preferred embodiments, the conductive material includes one or more of a metal, a conductive polymer, and a conductive ceramic.

[0094] Suitable conductive metals include aluminum, silver, nickel, gold, platinum, copper, tungsten, and alloys thereof. In some embodiments, the conductive material comprises metal powder suspended in a glue such as epoxy. In one embodiment, the conductive material comprises silver-containing epoxy.

[0095] Suitable conductive polymers include PEDOT (poly(3,4-ethylenedioxythiophene)), PSS (poly(p-phenylene sulfide)), PEDOT:PSS (a mixture of PEDOT and PSS), PANI (polyaniline), PPY (poly(pyrrole)), PPV (poly(p-phenylene vinylene)), or any combination thereof.

[0096] Suitable conductive ceramics include ITO (indium tin oxide), SLT (lanthanum-doped strontium titanate), SYT (yttrium-doped strontium titanate), or any combination thereof.

[0097] The printable conductive material may further include one or more additives selected from the group consisting of: a solvent; a curing agent; an adhesion promoter; a surfactant; a viscosity reducer; and an aggregation inhibitor. For example, such additives may be used to aid deposition of the conductive material onto the porous outer surface of the capillary body, to increase diffusion of the conductive material into the porous outer surface of the capillary body, to reduce the time required for the conductive material to solidify, to improve adhesion between the conductive material and the capillary body, or to reduce the aggregation of suspended particles (such as metal particles or powder) in the conductive material prior to application to the porous outer surface of the capillary body.

[0098] The printed conductive material printed on the porous outer surface of the capillary body can be cured in any suitable known manner to form the at least one heating element. For example, the printed conductive material can be cured by exposure to heat or ultraviolet light. Alternatively or additionally, the printed conductive material can be cured by sintering or by initiating a chemical reaction. In one specific embodiment, the printed conductive material comprises copper and is cured by initiating a chemical reaction to form the at least one heating element.

[0099] In certain embodiments, the method further comprises the step of heat-treating the conductive material to increase the electrical conductivity of the at least one heating element. In a particular embodiment, the conductive material comprises a conductive ceramic such as indium tin oxide, and the method further comprises the step of heat-treating the conductive material to grow micro-grains of the ceramic and thereby increase its electrical conductivity.

[0100] Features described in relation to one or more aspects may equally apply to the other aspects of the invention. In particular, features described in relation to the heater assembly of the first aspect may equally apply to the cartridge of the second aspect, and vice versa, and features described in relation to the heater assembly of the first aspect or the cartridge of the second aspect may equally apply to the aerosol generating system of the third aspect or the manufacturing method of the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0101] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0102] Figures 1A to 1D is a schematic diagram of a system incorporating a cartridge according to one embodiment of the present invention;

[0103] Figure 2 is an exploded view of the box of the system shown in Figure 1;

[0104] Figures 3A to 3E First through fifth example heater assemblies are shown; and

[0105] Figure 4 Shows the Figure 3A and Figure 3E Graphs of temperature versus distance on the outer surface of the capillary body for each arrangement. DETAILED DESCRIPTION

[0106] Figures 1A to 1D is a schematic diagram of an aerosol generating system comprising a cartridge according to an embodiment of the invention. Figure 1A is a schematic diagram of an aerosol generating device 10 or main unit and a separate cartridge 20, which together form an aerosol generating system. In this example, the aerosol generating system is an electrically operated smoking system.

[0107] The cartridge 20 contains the aerosol-forming substrate and is configured to be received in the cavity 18 within the device. The cartridge 20 should be replaceable by the user when the aerosol-forming substrate provided in the cartridge is exhausted. Figure 1A The cassette 20 is shown just before insertion into the device, wherein Figure 1A The arrow 1 in the figure indicates the direction of insertion of the cartridge.

[0108] The aerosol generating device 10 is portable and has a size comparable to a conventional cigar or cigarette. The device 10 comprises a main body 11 and a mouthpiece portion 12. The main body 11 contains a battery 14 (such as a lithium iron phosphate battery), control electronics 16 and a cavity 18. The mouthpiece portion 12 is connected to the main body 11 by a hinged connection 21 and can be used in various positions such as Figures 1A to 1C The open position shown is the same as Figure 1D The mouthpiece portion 12 is movable between the closed position shown. As will be described, the mouthpiece portion 12 is placed in the open position to allow the cartridge 20 to be inserted and removed, and is placed in the closed position when the system is to be used to generate an aerosol. The mouthpiece portion includes a plurality of air inlets 13 and outlets 15. In use, the user sucks or draws on the outlets to inhale air from the air inlets 13, through the mouthpiece portion to the outlets 15, and then into the user's mouth or lungs. As will be described, an internal baffle 17 is provided to force air flowing through the mouthpiece portion 12 to pass through the cartridge.

[0109] The cavity 18 has a circular cross-section and is sized to receive the housing 24 of the cartridge 20. Electrical connectors 19 are provided on the sides of the cavity 18 to provide electrical connection between the control electronics 16 and the battery 14 and corresponding electrical contacts on the cartridge 20.

[0110] Figure 1B Show Figure 1A The system of wherein the box is inserted in the cavity 18 and the cover 26 is being removed. In this position, the electrical connector rests on the electrical contacts on the box, as will be described.

[0111] Figure 1C Show Figure 1B A system in which the cover 26 is completely removed, and

[0112] The nozzle portion 12 moves to the closed position.

[0113] Figure 1D Show Figure 1C The system of claim 1, wherein the nozzle portion 12 is in a closed position. The nozzle portion 12 is held in the closed position by a fastening mechanism (not shown). It will be apparent to one of ordinary skill in the art that other suitable mechanisms for holding the nozzle in the closed position, such as a snap fit or a magnetic closure, may be used.

[0114] The nozzle portion 12 in the closed position maintains electrical contact between the cartridge and the electrical connector 19, allowing a good electrical connection to be maintained during use regardless of the system's orientation. The nozzle portion 12 may include an annular elastomeric element that engages the surface of the cartridge and is compressed between the rigid nozzle housing element and the cartridge when the nozzle portion 12 is in the closed position. This ensures that a good electrical connection is maintained despite manufacturing tolerances.

[0115] Of course, alternatively or additionally, other mechanisms for maintaining good electrical connection between the box and the device can be adopted. For example, the housing 24 of box 20 can be provided with a screw thread or groove (not shown) that engages with a corresponding groove or screw thread (not shown) formed in the wall of the cavity 18. The screw thread engagement between the box and the device can be used to ensure correct rotational alignment and the box is maintained in the cavity and ensure good electrical connection. The screw thread connection can only extend half a turn or be less than the box, or can extend several turns. Alternatively or additionally, the electrical connector 19 can be biased into contact with the contacts on the box.

[0116] Figure 21 is an exploded view of a box 20 suitable for an aerosol generating system (e.g., an aerosol generating system of the type shown in FIG1 ). Box 20 includes a generally circular cylindrical housing 24, the size and shape of which are selected to be accommodated in the corresponding cavities of other elements of the aerosol generating system, or to be installed in an appropriate manner on other elements of the aerosol generating system, such as the cavity 18 of the system of FIG1 . Housing 24 has an open end and accommodates an aerosol-forming substrate. In this example, the aerosol-forming substrate is a liquid, and housing 24 also contains a capillary body, which includes a capillary material 22 immersed in the liquid aerosol-forming substrate. In this example, the aerosol-forming substrate includes 39% by weight of glycerol, 39% by weight of propylene glycol, 20% by weight of water and flavorings, and 2% by weight of nicotine. Capillary material is a material that actively transmits liquid from one end to the other, and can be made of any suitable material. In this example, the capillary material is formed by polyester. In other examples, the aerosol-forming substrate can be solid.

[0117] Capillary material 22 has a porous outer surface 32, on which an electric heater 30 is fixed. Heater 30 comprises a pair of electrical contacts 34 fixed on the opposite side of porous outer surface 32 and a heating element 36 fixed to outer surface 32 and electrical contacts 34. In this example, heater 30 includes a single heating element 36 extending between the electrical contacts 34 and having a zigzag or zigzag arrangement. However, other arrangements of heaters may also be used, and this will be apparent to those skilled in the art. For example, heater can comprise a single heating element that adopts a double helix shape or follows more complicated twisted path or follows a basic linear path. Equally, heater can comprise a plurality of heating elements, for example a plurality of substantially parallel heating elements.

[0118] The electrical contacts 34 and the heater element 36 are integrally formed from a conductive material that has been deposited as a liquid directly onto the porous outer surface 32 and subsequently dried. Because the outer surface 32 is porous, the conductive material diffuses into the outer surface 32 during deposition so that when the conductive material dries, the heater 30 is securely attached to the capillary material 22. The diffusion of the conductive material into the outer surface 32 also increases the contact area between the heating element 36 and the capillary material 22, thereby increasing the efficiency of heat transfer from the heating element 36 to the capillary material 22.

[0119] The heater 30 is covered by a removable cover 26. The cover 26 comprises a liquid-impermeable plastic sheet that is glued to the heater assembly but can be easily peeled off. Tabs are provided on the sides of the cover 26 to allow the user to grasp the cover when peeling it off. It will now be apparent to those skilled in the art that while gluing is described as a method for securing the impermeable plastic sheet, other methods familiar to those skilled in the art, including heat sealing or ultrasonic welding, may also be used, as long as the cover 26 can be easily removed by the consumer.

[0120] It will be appreciated that other cartridge designs are possible. For example, the capillary material of the cartridge may comprise two or more separate capillary materials, or the cartridge may comprise a canister for containing a reservoir of free liquid.

[0121] The heater filaments of the heater element 36 are exposed through openings 35 in the substrate 34 so that vaporised aerosol-forming substrate can escape into the air flow passing through the heater assembly.

[0122] In use, the cartridge 20 is placed in an aerosol-generating system and the heater assembly 30 is connected to a power source included in the aerosol-generating system. Electronic circuitry is provided to power the heater element 36 and volatilize the aerosol-generating substrate. The vaporized aerosol-forming substrate can then escape into the airflow passing through the heater 30.

[0123] exist Figures 3A to 3E , the first to fifth examples of the arrangement of the electric heater 30 are described. In the first example, as Figure 3A As shown, the heater 30 includes diametrically opposed electrical contacts 34 and a single heating element 36 connected to the electrical contacts 34 and extending along a zigzag or zigzag path between the electrical contacts 34. In a second example, as shown in FIG. Figure 3B As shown, the heater 30 includes diametrically opposed electrical contacts 34 and a single heating element 36 connected to the electrical contacts 34 and extending along a double helical path between the electrical contacts 34. Figure 3C As shown, the heater 30 includes diametrically opposed electrical contacts 34 and a single heating element 36 connected to the electrical contacts 34 and extending along a tortuous path between the electrical contacts 34. Figure 3D As shown, the heater 30 includes diametrically opposed electrical contacts 34 and a plurality of heating elements 36 connected to the electrical contacts 34 and extending along substantially parallel paths between the electrical contacts 34. Figure 3E As shown, the heater 30 and Figure 3AThe first example heater depicted in FIG is substantially the same, except that the cross-sectional area of ​​the heating element 36 varies across the porous outer surface 32 to vary the heating distribution of the heater 30 across the porous outer surface 32. Specifically, the width of the heating element 36 narrows toward the periphery of the outer surface 32 and increases toward the center of the porous outer surface 32. Figure 3A 32, which results in a decrease in the amount of heat generated by the heating element toward the center of the porous outer surface 32 and an increase in the amount of heat generated by the heating element toward the periphery of the porous outer surface 32. This allows the electric heater to compensate for heat losses at the periphery of the outer surface, such as heat losses due to thermal conduction, and reduces the temperature at the center of the porous outer surface, thereby resulting in a more uniform temperature across the porous outer surface, as discussed below with respect to Figure 4 discussed.

[0124] Figure 4 It is aimed at Figure 3A and Figure 3E The temperature on the outer surface of the capillary body of each arrangement is plotted against the distance. Curve A shows Figure 3A Curve E shows the temperature of the first example heater. Figure 3E The temperature of the fifth example heater is shown in Figure 1. As shown by curve A, the temperature of the porous outer surface of the first example heater is lower toward its periphery and increases toward its center, forming a hot spot in a narrow area at the center of the heating element. As shown by curve E, the temperature of the porous outer surface of the fifth example heater is higher toward its periphery than that of the porous outer surface of the first example heater. Furthermore, the temperature of the fifth example heater is lower at the center and extends over a wider area, as shown by curve E. Therefore, the temperature distribution on the porous outer surface of the fifth example heater is more uniform, particularly in the center area, compared to the first example heater.

[0125] When the cartridge is assembled, the heating element 36 is in direct contact with the capillary material 22, and thus the aerosol-forming substrate can be delivered directly to the heater. In examples of the present invention, the aerosol-forming substrate contacts most, if not all, of the surface of the heating element 36, so that most of the heat generated by the heater assembly goes directly into the aerosol-forming substrate. In contrast, in conventional wick heater assemblies and coil heater assemblies, only a small portion of the heating filaments is in contact with the aerosol-forming substrate.

[0126] In use, the heater assembly is preferably operated by resistive heating, but it may also be operated using other suitable heating processes (such as induction heating). In the case where the heater assembly operates by resistive heating, current is passed through the heater under the control of the control electronics 16 to heat the filament to a desired temperature range. The heating element 36 has a significantly higher resistance than the electrical contacts 34, so that the high temperature is localized on the heating element. The system can be configured to generate heat by providing current to the heater in response to the user drawing on it, or it can be configured to generate heat continuously when the device is in the "on" state. Different materials for the elements may be suitable for different systems. For example, in a continuous heating system, a material with a relatively low specific heat capacity is suitable and compatible with low current heating. In a suction-actuated system that uses high current pulses to generate heat in short pulses, a material with a high specific heat capacity may be more suitable.

[0127] In a puff-activated system, the device may include a puff sensor configured to detect when a user is inhaling air through the mouthpiece. The puff sensor (not shown) is connected to the control electronics 16, and the control electronics 16 is configured to supply current to the heater 30 only when it is determined that the user is taking a puff on the device. Any suitable air flow sensor may be used as the puff sensor, such as a microphone.

[0128] In one possible embodiment, a change in the resistivity of at least one heating element can be used to detect a changing temperature. This can be used to adjust the power supplied to the heater to ensure that it remains within the desired temperature range. Sudden changes in temperature can also be used as a means of detecting changes in airflow through the heating element caused by the user puffing on the system. One or more elements can be dedicated temperature sensors and can be formed of a material with a suitable temperature coefficient of resistance for this purpose (such as an iron-aluminum alloy, Ni-Cr, platinum, tungsten or an alloy).

[0129] Figure 1D shows the airflow through the mouthpiece when the system is in use. The mouthpiece includes an internal baffle 17, which is integrally molded with the outer wall of the mouthpiece and ensures that as air is drawn from the air inlet 13 to the outlet 15, it flows through the heater 30 on the cartridge, where the aerosol-forming substrate is being vaporized. As the air passes through the heater assembly, the vaporized substrate is entrained in the airflow and cooled before exiting the outlet 15 to form an aerosol.

[0130] While the described embodiment has a box with a housing having a substantially circular cross-section, it is of course possible to form a box housing having other shapes, such as a rectangular cross-section or a triangular cross-section. These housing shapes will ensure the desired orientation within the correspondingly shaped cavity to ensure electrical connection between the device and the box.

[0131] Those skilled in the art will readily envision other cartridge designs incorporating heater assemblies according to the present disclosure. For example, the cartridge may include a nozzle portion and may have any desired shape. Furthermore, heaters according to the present disclosure may be used in other types of systems such as those already described, such as humidifiers, air fresheners, and other aerosol generating systems.

[0132] Example 1

[0133] EpoTek (RTM) H20E (a silver-containing epoxy conductive adhesive available from Epoxy Technology, Inc., Billerica, Montana, USA) was manually dispensed with a needle onto a capillary body formed from Sterlitech GB140 (a fiberglass capillary material available from Sterlitech, Inc., Kent, Washington, USA) to form the heater's heating element and electrical contacts. To test the heater, an Agilent N6705B programmable power supply was used to pass current through the heater for 3 seconds. The current was supplied at a voltage of 3.55V and a power of 4.3W. During the test, an infrared camera was used to record the temperature of the outer surface of the capillary body.

[0134] Example 2

[0135] EpoTek (RTM) H20E (silver-containing epoxy conductive adhesive available from Epoxy Technology, Inc., Billerica, Montana, USA) was manually dispensed with a needle onto the capillary body to form the heater's heating element and electrical contacts. The capillary body was formed from a porous ceramic capillary material with a pore size of 20 microns and a porosity of 40%-45%. To test the heater, an Agilent N6705B programmable power supply was used to pass current through the heater for 3 seconds. The current was supplied at a voltage of 3.55V and a power of 4.3W. The heater resistance was measured at 2.3 ohms. During the test, an infrared camera was used to record the temperature of the outer surface of the capillary body, which peaked at 185 degrees Celsius.

[0136] The exemplary embodiments described above are illustrative and not restrictive. In view of the exemplary embodiments discussed above, other embodiments consistent with the exemplary embodiments described above will now be apparent to those of ordinary skill in the art.

Claims

1. A cartridge for an aerosol generating system, the cartridge comprising: a liquid storage portion configured to contain a liquid aerosol-forming substrate; and A heater assembly comprising: an electric heating element configured to heat the liquid aerosol-forming substrate to form an aerosol, and a capillary body having a porous outer surface and configured to convey the liquid aerosol-forming substrate to the electric heating element, the electric heating element being disposed along the porous end face of the capillary body, wherein the liquid storage portion is disposed at a first end of the heater assembly, and a first airflow channel is disposed at an end of the heater assembly opposite the first end and adjacent the electric heating element, thereby defining an airflow path extending through the electric heating element and configured to convey an aerosol; Wherein, the box further comprises: A suction nozzle portion, the suction nozzle portion having an air inlet and an air outlet; a second airflow path extending in a first direction from the air inlet toward the heater assembly; and a third airflow channel extending from the heater assembly to the air outlet in a second direction, wherein the first direction is opposite to the second direction; The airflow path provides a fluid connection between the second airflow channel and the third airflow channel.

2. The cartridge according to claim 1, wherein The electric heating element extends along the porous end surface in a curved or serpentine shape.

3. The cartridge according to claim 1, wherein The electric heating element extends along the porous end surface in a zigzag or zigzag shape.

4. The cartridge according to claim 1, wherein The capillary body comprises ceramic.

5. The cartridge according to claim 1, wherein The porous end surface on which the electric heating element is arranged is substantially flat.

6. The cartridge according to claim 1, wherein The heater assembly also includes electrical contacts connected to the electrical heating element, each electrical contact being disposed on opposite sides of the porous end face such that the electrical heating element extends between the electrical contacts and forms an electrical connection therebetween.

7. The cartridge according to claim 1, wherein The electrical heating element extends at least partially into the porous end face.

8. The box according to claim 1, further comprising at least one air inlet and an outlet configured to deliver the aerosol to a user, The distance between the at least one air inlet and the outlet in a direction parallel to the longitudinal axis of the box is smaller than the distance between the electric heating element and the outlet in a direction parallel to the longitudinal axis of the box.

9. The cartridge according to claim 8, wherein The box also includes a plurality of air inlets and a single air outlet.

10. The cartridge according to claim 1, wherein The liquid storage portion comprises a housing for containing a liquid aerosol-forming substrate, the housing having an opening, wherein the capillary body is arranged such that the electric heating element extends through the opening.

11. A method of manufacturing a cartridge for an aerosol generating system, the method comprising the steps of: providing a liquid storage portion for containing the liquid aerosol-forming substrate; providing a capillary body having a porous outer surface; embedding an electric heating element into the porous end surface of the capillary body; filling the liquid storage portion with a liquid aerosol-forming substrate; connecting the liquid storage portion to a first end of the heater assembly to allow liquid aerosol-forming substrate contained in the liquid storage portion to be transferred through the capillary body to the electric heating element, wherein a first airflow channel is provided at an end of the heater assembly opposite the first end and adjacent the electric heating element to define an airflow path extending through the electric heating element and configured to transfer an aerosol; and providing a nozzle portion having an air inlet and an air outlet, wherein a second air flow channel extends in a first direction from the air inlet toward the heater assembly, and a third air flow channel extends in a second direction from the heater assembly to the air outlet, wherein the first direction is opposite to the second direction; The airflow path provides a fluid connection between the second airflow channel and the third airflow channel.

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