Aerosol generation system having fluid permeable heater assembly

Abstract

To provide a heater assembly suitable for an aerosol generation system.SOLUTION: There is provided an aerosol generation system having a fluid permeable electric heater assembly. The heater assembly includes an electrically insulated substrate, an opening formed in the electrically insulated substrate, and a heater element having a first face fixed to the electrically insulated substrate. The heater element includes a plurality of conductive filaments that cross the opening and are connected to first and second conductive contact parts. The first and second conductive contact parts are arranged opposed to each other on the opposite side of the opening. The first and second conductive contact parts are configured so as to come in contact with an external power source.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an aerosol generating system including a heater assembly suitable for vaporizing a liquid. In particular, the present invention relates to a handheld aerosol generating system, such as an electrically operated smoking system. [Background technology]

[0002] Electrically operated smoking systems that vaporize a liquid by heating to form an aerosol typically include a coil of wire wrapped around a capillary material that holds the liquid. Electric current passed through the wire causes resistive heating of the wire, vaporizing the liquid within the capillary material. The capillary material is typically held within an airflow path so that air is drawn through a wick and entrained in the vapor. The vapor then cools to form an aerosol.

[0003] While this type of system is effective at generating aerosols, it can be difficult to manufacture in a low-cost and repeatable manner, and the core and coil assembly, along with the associated electrical connections, can be fragile and difficult to handle.

[0004] It is desirable to provide a heater assembly suitable for aerosol generating systems, such as handheld, electrically operated smoking systems, that is inexpensive to manufacture and durable. It is further desirable to provide a heater assembly that is more efficient than previous heater assemblies for aerosol generating systems. Summary of the Invention

[0005] In one aspect, an aerosol generating system is provided with a fluid-permeable electric heater assembly, the heater assembly including an electrically insulating substrate, an opening formed in the electrically insulating substrate, and a heater element secured to the electrically insulating substrate, the heater element including a plurality of conductive filaments spanning the opening and connected to first and second conductive contact portions, the first and second conductive contact portions positioned opposite each other on opposite sides of the opening, wherein the first and second conductive contact portions are configured for contact with an external power source.

[0006] The plurality of conductive filaments may form a mesh or array of filaments, or may comprise a woven or nonwoven fabric.

[0007] Advantageously, the heater element has a first surface fixed to an electrically insulating substrate, and the first and second conductive contact portions are configured for contact with an external power source on a second surface of the heater element opposite the first surface.

[0008] The system may further comprise a liquid storage portion including a housing containing the liquid aerosol-forming substrate, wherein the heater assembly is secured to the liquid storage portion housing. The housing is preferably rigid and impermeable to fluids. As used herein, "rigid housing" means a free-standing housing. The rigid liquid storage portion housing preferably provides mechanical support for the heater assembly.

[0009] The liquid reservoir may comprise a capillary material configured to communicate the liquid aerosol-forming substrate to the heater assembly.

[0010] Providing this type of heater assembly in an aerosol generation system has several advantages over conventional wick and coil arrangements: A heater element comprising a mesh or array of filaments increases the area of ​​the heater in contact with the liquid to be vaporized; The heater assembly can be manufactured inexpensively using readily available materials and mass production techniques; The heater assembly is robust, allowing for handling during manufacture and fastening to other components of the aerosol generation system, particularly to form part of a removable cartridge; and The provision of conductive contact portions forming part of the heater element allows for reliable and simple connection of the heater assembly to a power source.

[0011] The conductive filaments may be substantially flat. As used herein, "substantially flat" means formed in a single plane and not wound around or adapted to conform to a curved or other non-planar shape. A flat heater assembly allows for easier handling during manufacturing and provides a sturdy structure.

[0012] The conductive filaments may define gaps between them, which may have a width of 10 μm to 100 μm. The filaments preferably induce capillary action within the gaps so that in use, liquid to be vaporized is drawn into the gaps, increasing the contact area between the heater assembly and the liquid.

[0013] The conductive filaments may form a mesh with a size of 160 to 600 mesh US (±10%) (i.e., 160 to 600 filaments per inch (±10%)). The gap width is preferably 75 μm to 25 μm. The mesh open area ratio, which is the ratio of the gap area to the total mesh area, is preferably 25 to 56%. The mesh may be formed using different types of weave or lattice structures. Alternatively, the conductive filaments may consist of a series of filaments aligned parallel to one another.

[0014] A mesh, array or fiber of conductive filaments may also be characterized by its ability to retain liquid, as is well known in the art.

[0015] The diameter of the conductive filament can be 8 μm to 100 μm, preferably 8 μm to 50 μm, and more preferably 8 μm to 39 μm.

[0016] The area of ​​the mesh, array or fiber of conductive filaments can be small, 25 mm 2 Preferably, the conductive filament mesh, array, or fiber is less than 100 mm thick, allowing for incorporation into handheld systems. The conductive filament mesh, array, or fiber may be rectangular, for example, having dimensions of 5 mm x 2 mm. Preferably, the conductive filament mesh or array covers an area of ​​10% to 50% of the area of ​​the heater assembly. More preferably, the conductive filament mesh or array covers an area of ​​15% to 25% of the area of ​​the heater assembly.

[0017] The conductive filaments may comprise any suitable conductive material. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may include doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable alloys include stainless steel, constantan, nickel-, cobalt-, chromium-, aluminum-titanium-zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, and iron-containing alloys, as well as nickel-, iron-, cobalt-, and stainless steel-based superalloys, Timetal®, iron-aluminum-based alloys, and iron-manganese-aluminum-based alloys. Timetal® is a registered trademark of Titanium Metals Corporation. The filaments may be coated with one or more insulators. Preferred materials for the conductive filaments are 304, 316, 304L, 316L stainless steel, and graphite.

[0018] The electrical resistance of the conductive filament mesh, array, or fiber of the heater element is preferably 0.3 to 4 ohms. More preferably, the electrical resistance of the conductive filament mesh, array, or fiber is 0.5 to 3 ohms, and more preferably about 1 ohm. The electrical resistance of the conductive filament mesh, array, or fiber is preferably at least one order of magnitude greater than the electrical resistance of the contact points, and more preferably at least two orders of magnitude greater. This ensures that heat generated by passing current through the heater element is localized to the conductive filament mesh or array. When the system is battery-powered, it is advantageous for the heater element to have a low overall resistance. Minimizing unnecessary losses between the electrical contacts and the mesh or filament is also desirable to minimize unnecessary power loss. A low-resistance, high-current system allows for high power delivery to the heater element, enabling the heater element to quickly heat the conductive filament to the desired temperature.

[0019] The first and second conductive contact portions can be secured directly to the conductive filament. The contact portions can be disposed between the conductive filament and an electrically insulating substrate. For example, the contact portions can be formed from copper foil plated on an insulating substrate. The contact portions can also be more easily bonded to the filament than to the insulating substrate.

[0020] Alternatively, the first and second conductive contact portions may be integral with the conductive filament. For example, the heater element may be formed by etching a conductive sheet to provide multiple filaments between the two contact portions.

[0021] A heater assembly can include at least one filament made from a first material and at least one filament made from a second material different from the first material. This can be beneficial for electrical or mechanical reasons. For example, one or more filaments can be formed from a material whose resistance varies significantly with temperature, such as an iron-aluminum alloy. This allows measurement of the resistance of the filament to be used to determine temperature or temperature change. This can be used in smoke detection systems to control the heater temperature to keep the heater within a desired temperature range.

[0022] The electrically insulating substrate may comprise any suitable material, preferably one that can withstand high temperatures (greater than 300°C) and rapid temperature changes. One example of a suitable material is a polyimide film such as Kapton®.

[0023] An aerosol-forming substrate is a substrate capable of releasing a volatile compound capable of forming an aerosol. The volatile compound can be released by heating the aerosol-forming substrate.

[0024] The aerosol-forming substrate may comprise a plant-derived material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise 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 comprise a non-tobacco-containing material. The aerosol-forming substrate may comprise a homogenized plant-derived material. The aerosol-forming substrate may comprise a homogenized tobacco material. The aerosol-forming substrate may comprise at least one aerosol-forming agent. The aerosol-forming agent is any suitable known compound or mixture of compounds that facilitates the formation of a dense, stable aerosol upon use and is substantially resistant to thermal decomposition at the operating temperatures of the system. Suitable aerosol-forming agents are well known in the art and include, but are not limited to, polyhydric alcohols (e.g., triethylene glycol, 1,3-butanediol, and glycerin), esters of polyhydric alcohols (e.g., glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (e.g., dimethyl dodecanedioate and dimethyl tetradecanedioate). Preferred aerosol formers are polyhydric alcohols or mixtures thereof, such as triethylene glycol, 1,3-butanediol, and glycerin (most preferred). The aerosol-forming substrate may contain other additives and ingredients, such as flavorings.

[0025] The capillary material may have a fibrous or spongy structure. Preferably, the capillary material comprises a bundle of capillaries. For example, the capillary material may comprise a plurality of fibers or threads or other fine tubes. The fibers or threads may be generally aligned to transport the liquid to the heater. Alternatively, the capillary material may comprise a spongy or foam-like material. The structure of the capillary material forms a plurality of small holes or tubes through which the liquid can travel by capillary action. The capillary material may comprise any suitable material or combination of materials. Examples of suitable materials include spongy or foam materials, ceramic or graphite-based materials in the form of fibers or sintered powders, foamed metal or plastic materials, and fibrous materials made from spun or extruded fibers (such as cellulose acetate, polyester, or bonded polyolefin, polyethylene, terylene, or polypropylene fibers, nylon fibers, or ceramics). The capillary material may have any suitable capillary and porosity to accommodate different liquid physical properties. A liquid has physical properties, including but not limited to viscosity, surface tension, density, thermal conductivity, boiling point and vapor pressure, that allow it to move through a capillary device by capillary action.

[0026] The capillary material may be in contact with the conductive filaments. The capillary material may extend into the gaps between the filaments. The heater assembly may draw the liquid aerosol-forming substrate into the gaps by capillary action. The capillary material may be in contact with the conductive filaments over substantially the entire length of the opening.

[0027] The housing may include two or more different capillary materials, where a first capillary material in contact with the heater element has a higher thermal decomposition temperature and a second capillary material in contact with the first capillary material but not the heater element has a lower thermal decomposition temperature. The first capillary material effectively serves as a spacer separating the heater element from the second capillary material, preventing the second capillary material from being exposed to temperatures above 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 generating gaseous by-products. The second capillary material may advantageously occupy a larger volume than the first capillary material, but may also hold more aerosol-forming substrate than the first capillary material. The second capillary material may have better wick performance than the first capillary material. The second capillary material may be less expensive or have a higher filling capacity than the first capillary material. The second capillary material may be polypropylene.

[0028] The first capillary material may separate the heater assembly from the second capillary material by a distance of at least 1.5 mm, but preferably between 1.5 and 2 mm to provide a sufficient temperature drop across the first capillary material.

[0029] The liquid reservoir may be located on a first side of the conductive filament, and the airflow channel may be located on the opposite side of the conductive filament from the liquid reservoir, such that air flow passing through the conductive filament is entrained in the vaporized liquid aerosol-forming substrate.

[0030] The system may further comprise an electrical circuit connected to the heater element and the power supply, the electrical circuit configured to monitor the electrical resistance of the heater element, or of one or more filaments of the heater element, and to control the supply of power to the heater element from the power supply depending on the electrical resistance of the heater element, or in particular the electrical resistance of the one or more filaments.

[0031] The electrical circuitry may comprise a microprocessor, which may be a programmable microprocessor, microcontroller, or application specific integrated circuit chip (ASIC) or other electronic circuitry with control capabilities. The electrical circuitry may comprise additional electronic components. The electrical circuitry may be configured to regulate power supply to the heater. Power may be supplied to the heater element continuously after system activation, or intermittently, such as with each puff. Power may be supplied to the heater element in the form of current pulses.

[0032] Advantageously, the system includes a power source (typically a lithium-ion phosphate battery or similar) within the body of the housing. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may be rechargeable and may have a capacity that allows for the storage of sufficient energy for one or more smoking experiences. For example, the power source may have a capacity sufficient to allow for continuous production of aerosol for a period of approximately six minutes, corresponding to the typical time it takes to smoke a conventional cigarette, or for a multiple of six minutes. In another example, the power source may have a capacity sufficient to allow for a predetermined number of puffs or for discontinuous activation of the heater.

[0033] The system may include a main unit and a cartridge removably coupled to the main unit, where the liquid reservoir and heater assembly are provided within the cartridge, and the main unit includes a power source. As used herein, a cartridge "removably coupled" to a device means that the cartridge and device can be connected and disconnected from one another without significant damage to either the device or the cartridge.

[0034] The system may be an electrically operated smoking system. The system may be a handheld aerosol generating system. The aerosol generating system may have a size comparable to a conventional cigar or cigarette. The overall length of the smoking system may be between about 30 mm and about 150 mm. The outer diameter of the smoking system may be between about 5 mm and about 30 mm.

[0035] In a second aspect, a fluid-permeable electric heater assembly is provided that includes an electrically insulating substrate, an opening formed in the electrically insulating substrate, and a heater element having a first surface spanning the opening and secured to the electrically insulating substrate, the heater element including a plurality of conductive filaments connected to first and second conductive contact portions, the first and second conductive contact portions positioned opposite each other on opposite sides of the opening, wherein the first and second conductive contact portions are configured for contact with an external power source.

[0036] In a third aspect, there is provided a method of manufacturing a fluid-permeable electric heater assembly suitable for use in an aerosol generating system, the method comprising: providing an electrically insulating substrate; forming one or more openings in a substrate; providing a heater element on the substrate across the one or more openings, the heater element including a plurality of conductive filaments and at least two conductive contact portions on opposite sides of the one or more openings from each other.

[0037] In a fourth aspect, there is provided a method of manufacturing a plurality of fluid-permeable electric heater assemblies suitable for use in an aerosol generating system, the method comprising: providing an electrically insulating substrate; forming a plurality of openings in a substrate; providing a plurality of conductive contact portions on the substrate opposite a plurality of respective openings; providing a plurality of conductive filaments on the substrate extending across a plurality of respective openings and between conductive contact portions to provide an array of heater assemblies; and cutting a plurality of individual heater assemblies from the array of heater assemblies, each heater assembly including one of the openings.

[0038] The electrically insulating substrate may be a flexible sheet material. The conductive contact portions and the conductive filaments may be integrally formed with one another.

[0039] Features described in relation to one aspect may be applied to other aspects of the invention, and in particular features described in relation to the heater assembly of the first aspect of the invention may be equally applied to the heater assembly of the second aspect of the invention.

[0040] As used herein, "electrically conductive" means a resistivity of 1×10 -4 As used herein, "insulating" means being made of a material with a resistivity of 1×10 Ωm or less. 4 This means that it is made from a material with a resistance of Ωm or higher.Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0041] [Figure 1a] FIG. 1a is a schematic diagram of a system incorporating a cartridge according to an embodiment of the present invention. [Figure 1b] FIG. 1b is a schematic diagram of a system incorporating a cartridge according to an embodiment of the present invention. [Figure 1c] FIG. 1c is a schematic diagram of a system incorporating a cartridge according to an embodiment of the present invention. [Figure 1d] FIG. 1d is a schematic diagram of a system incorporating a cartridge according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a clasp mechanism for the mouthpiece portion of the system of FIG. [Figure 3] FIG. 3 is an exploded view of the cartridge of FIGS. 1a to 1d. [Figure 4] FIG. 4 is an exploded view of an alternative cartridge for use in the system shown in FIGS. 1a-1d. [Figure 5a] 5a is a perspective view of the underside of the cartridge of FIG. 2. FIG. [Figure 5b]FIG. 5b is a perspective view of the top of the cartridge of FIG. 2 with the cover removed. [Figure 6] FIG. 6 is a detailed view of the heater assembly used in the cartridge shown in FIG. [Figure 7] FIG. 7 is a detailed view of an alternative heater assembly that may be used with the cartridge shown in FIG. [Figure 8] FIG. 8 is a detailed view of a further alternative heater assembly that may be used with the cartridge shown in FIG. [Figure 9] FIG. 9 is a detailed view of yet a further alternative heater assembly that may be used in the cartridge shown in FIG. [Figure 10] FIG. 10 is a detailed view of an alternative mechanism for making electrical contact between the device and the heater assembly. [Figure 11a] Figure 11a illustrates some cartridge housing shapes that may be used to ensure proper alignment of the cartridge within the device. [Figure 11b] Figure 11b illustrates some cartridge housing shapes that may be used to ensure proper alignment of the cartridge within the device. [Figure 12a] FIG. 12a is a detailed view of the heater filaments, showing the meniscus of the liquid aerosol-forming substrate between the filaments. [Figure 12b] FIG. 12b is a detailed view of the heater filaments, showing the meniscus of the liquid aerosol-forming substrate between the filaments and the capillary material extending between them. [Figure 13a] FIG. 13a illustrates an alternative manufacturing method for a heater assembly according to the present invention. [Figure 13b] FIG. 13b illustrates an alternative manufacturing method for a heater assembly according to the present invention. [Figure 13c] FIG. 13c illustrates an alternative manufacturing method for a heater assembly according to the present invention. [Figure 14] FIG. 14 illustrates an alternative design for the liquid reservoir incorporating a heater assembly. [Figure 15a] FIG. 15a illustrates a further alternative embodiment of a liquid reservoir incorporating a heater assembly. [Figure 15b] FIG. 15b illustrates a further alternative embodiment of a liquid reservoir incorporating a heater assembly. [Figure 16] FIG. 16 illustrates an alternative embodiment of the airflow and cartridge orientation with the aerosol generating device. DETAILED DESCRIPTION OF THE INVENTION

[0042] 1a-1d are schematic diagrams of an aerosol generation system including a cartridge according to an embodiment of the present invention. Figure 1a is a schematic diagram of an aerosol generation device 10 and a separate cartridge 20, which together form the aerosol generation system. In this example, the aerosol generation system is an electrically operated smoking system.

[0043] The cartridge 20 contains an aerosol-forming substrate and is configured to be received in a recess 18 in the device. The cartridge 20 should be replaceable by the user when the aerosol-forming substrate provided therein is depleted. Figure 1a shows the cartridge 20 just prior to insertion into the device, with arrow 1 in Figure 1a indicating the direction of insertion of the cartridge.

[0044] The aerosol generating device 10 is portable and has a size comparable to that of a conventional cigar or cigarette. The device 10 includes a body 11 and a mouthpiece portion 12. The body 11 includes a battery 14 (e.g., a lithium iron phosphate battery), control electronics 16, and a recess 18. The mouthpiece portion 12 is connected to the body 11 by a hinged connection 21 and is movable between an open position shown in FIG. 1 and a closed position shown in FIG. 1d. The mouthpiece portion 12 is positioned in the open position to allow insertion and removal of a cartridge 20 and in the closed position when the system is used to generate aerosol, as described below. The mouthpiece portion includes multiple air inlets 13 and outlets 15. In use, a user draws or inhales through the outlets to draw air from the air inlets 13, through the mouthpiece portion, and into the outlets 15, which then enter the user's mouth or lungs. An internal baffle 17 is provided to force air flow through the cartridge and through the mouthpiece portion 12, as described below.

[0045] The cavity 18 has a circular cross section and is sized to receive the housing 24 of the cartridge 20. An electrical connector 19 is provided on the side of the cavity 18 to provide electrical connection between the control electronics 16 and battery 14 and corresponding electrical contacts on the cartridge 20.

[0046] Figure 1b shows the system of Figure 1a with the cartridge inserted into the cavity 18 and the cover 26 removed. In this position, the electrical connector rests against electrical contacts on the cartridge, as described below.

[0047] FIG. 1c shows the system of FIG. 1b with the cover 26 completely removed and the mouthpiece portion 12 moved to the closed position.

[0048] FIG. 1d shows the system of FIG. 1c with mouthpiece portion 12 in a closed position. Mouthpiece portion 12 is held in the closed position by a clasp feature, as shown schematically in FIG. 2. FIG. 2 illustrates body 11 and mouthpiece portion 12 connected by hinged connection 21. Mouthpiece portion 12 includes inwardly extending teeth 8. When the mouthpiece portion is in the closed position, teeth 8 engage with clasp 6 on the body of the device. Clasp 6 is biased into engagement with teeth 8 by bias spring 5. Button 4 is secured to clasp 6. Button 4 can be pressed by a user against the action of bias spring 5 to release teeth 8 from clasp 6, allowing the mouthpiece portion to move to the open position. It will be apparent to one of ordinary skill in the art that other suitable mechanisms, such as a snap-fit ​​or magnetic closure, can be used to hold the mouthpiece in the closed position.

[0049] The mouthpiece portion 12 in the closed position keeps the cartridge in electrical contact with the electrical connector 19 so that a good electrical connection is maintained during use regardless of the orientation of the system. The mouthpiece portion 12 may include an annular resilient element that engages a surface of the cartridge and is compressed between the rigid mouthpiece housing element and the cartridge when the mouthpiece portion 12 is in the closed position. This maintains a good electrical connection regardless of manufacturing tolerances.

[0050] Of course, other mechanisms for maintaining a good electrical connection between the cartridge and the device may alternatively or additionally be employed. For example, the housing 24 of the cartridge 20 may be provided with threads or grooves (not shown) that engage with corresponding grooves or threads (not shown) formed in the walls of the recess 18. The threaded engagement between the cartridge and the device may be used to ensure proper rotational alignment, as well as to retain the cartridge within the recess and ensure a good electrical connection. The threaded connection may extend less than one-half turn of the cartridge, or may extend several turns. Alternatively, or additionally, the electrical connector 19 may be biased to make contact with contacts on the cartridge, as described with reference to FIG. 8.

[0051] FIG. 3 is an exploded view of cartridge 20. Cartridge 20 includes a generally cylindrical housing 24 having a size and shape selected to be received within cavity 18. The housing contains a capillary material 22 immersed in a liquid aerosol-forming substrate. In this example, the aerosol-forming substrate includes 39 weight percent glycerin, 39 weight percent propylene glycol, 20 weight percent water and flavorings, and 2 weight percent nicotine. The capillary material is a material that actively transports liquid from one end to the other and can be made from any suitable material. In this example, the capillary material is formed from polyester.

[0052] The housing has an open end in which a heater assembly 30 is secured. The heater assembly 30 includes a base 34 having an opening 35 formed therein, a pair of electrical contacts 32 secured to the base and separated from one another by a gap 33, and a plurality of conductive heater filaments 36 secured across the opening to the electrical contacts on opposite sides of the opening 35.

[0053] The heater assembly 30 is covered by a removable cover 26. The cover comprises a liquid-impermeable plastic sheet that is adhered to the heater assembly but is easily removable. Tabs are provided on the sides of the cover to allow the user to grasp the cover when removing it. It will be apparent to those skilled in the art that although adhesion is described as a method of securing the impermeable plastic sheet to the heater assembly, other methods familiar to those skilled in the art, including heat sealing or ultrasonic welding, may also be used, so long as the cover can be easily removed by the consumer.

[0054] FIG. 4 is an exploded view of an alternative exemplary cartridge. The cartridge of FIG. 4 is the same size and shape as the cartridge of FIG. 3, and has the same housing and heater assembly. However, the capillary material in the cartridge of FIG. 4 is different from that of FIG. 3. The cartridge of FIG. 4 has two separate capillary materials 27, 28. A disk of the first capillary material 27 is provided for contacting the heater elements 36, 32 during use. A larger body of the second capillary material 28 is provided on the opposite side of the first capillary material 27 to the heater assembly. Both the first and second capillary materials hold a liquid aerosol-forming substrate. The first capillary material 27, which contacts the heater elements, has a higher thermal decomposition temperature (at least 160° C. or higher, e.g., about 250° C.) than the second capillary material 28. The first capillary material 27 effectively serves as a spacer separating the heater elements 36, 32 from the second capillary material 28 so that the second capillary material is not exposed to temperatures above its thermal decomposition temperature. A thermal gradient across the first capillary material ensures that the second capillary material is exposed to temperatures below its thermal decomposition temperature. The second capillary material 28 can be selected to have good wicking properties to the first capillary material 27, can hold more liquid per unit volume than the first capillary material, and can be less expensive than the first capillary material. In this example, the first capillary material is a heat-resistant element such as glass fiber or a glass fiber-containing element, and the second capillary material is a polymer, such as a suitable capillary material. Exemplary suitable capillary materials include those discussed herein, and in alternative embodiments, can include high-density polyethylene (HDPE) or polyethylene terephthalate (PET).

[0055] FIG. 5a is a perspective view of the underside of the cartridge of FIG. 3. It can be seen from FIG. 5a that the heater assembly extends in a lateral plane and laterally beyond the housing 24 so that the heater assembly forms a lip around the top of the housing 24. The exposed portions of the electrical contacts 32 face the insertion direction of the cartridge so that they contact the electrical connector 19 when the cartridge is fully inserted into the cavity 18. Tabs on the sides of the cover 26 are clearly visible so that a user can grip the cover during removal. FIG. 5a also illustrates a positioning feature 25 formed in the base of the cartridge to ensure proper orientation of the cartridge within the device cavity. The positioning feature 25 is part of the injection-molded housing 24 and is configured to be received in a corresponding slot (not shown) in the base of the cavity 18. When the positioning feature 25 is received in the slot in the cavity, the contacts 32 are aligned with the connector 19.

[0056] Figure 5b is a perspective view of the top of the cartridge of Figure 3 with the cover removed. The heater filament 36 is exposed through an opening 35 in the substrate 34 to allow vaporized aerosol-forming substrate to escape into the airflow passing through the heater assembly.

[0057] The housing 24 is formed from a thermoplastic material such as polypropylene. In this example, the heater assembly 30 is glued to the housing 24. However, there are several possible ways to assemble and fill the cartridge.

[0058] The cartridge housing may be formed by injection molding. The capillary material 22, 27, 28 may be formed by cutting appropriate lengths of capillary material from a long rod of capillary fiber. The heater assembly may be assembled using the process described in connection with Figures 11a, 11b, and 11c. In one embodiment, the cartridge is assembled by first inserting one or more of the capillary material 22, 27, 28 into the housing 24. A predetermined volume of liquid aerosol-forming substrate is then introduced into the housing 24, immersing the capillary material. The heater assembly 30 is then pressed against the open end of the housing and secured to the housing 24 by adhesive, welding, heat sealing, ultrasonic welding, or other methods that will become apparent to those skilled in the art. During any sealing operation, the temperature of the housing is preferably kept below 160°C to prevent undesired volatilization of the aerosol-forming substrate. The capillary material may be cut to a length that extends out of the open end of the housing 24 until compressed by the heater assembly. This facilitates transport of the aerosol-forming substrate into the gap of the heater element in use.

[0059] In another embodiment, instead of pressing the heater assembly 30 into the housing 24 and then sealing it, the open end of the heater assembly and housing may first be rapidly heated and then the heater assembly 30 may be pressed together to bond it to the housing 24.

[0060] It is also possible to assemble the heater assembly 30 to the housing 24 before filling the housing with the aerosol-forming substrate, and introduce the aerosol-forming substrate into the housing 24. In that case, the heater assembly can be secured to the cartridge using any of the methods described. The heater assembly or housing is then pierced using a hollow needle, and the aerosol-forming substrate is injected into the capillary material 22, 27, 28. Any openings made by the hollow needle are then sealed using a heat seal or sealing tape.

[0061] FIG. 6 illustrates a first heater assembly 30 according to the present disclosure. The heater assembly includes a mesh formed from 304L stainless steel with a mesh size of approximately 400 mesh US (approximately 400 filaments per inch). The filaments have a diameter of approximately 16 μm. The mesh is connected to electrical contacts 32 separated from each other by gaps 33 and formed of copper foil with a thickness of approximately 30 μm. The electrical contacts 32 are provided on a polyimide substrate 34 with a thickness of approximately 120 μm. The filaments forming the mesh define gaps between them. In this example, the gaps have a width of approximately 37 μm, although larger or smaller gaps may be used. Using a mesh of these approximate dimensions allows a meniscus of the aerosol-forming substrate to form within the gaps, and the mesh of the heater assembly draws the aerosol-forming substrate through capillary action. The ratio of the open area of ​​the mesh, i.e., the area of ​​the gaps to the total area of ​​the mesh, is advantageously 25 to 56%. The total resistance of the heater assembly is approximately 1 ohm. The mesh provides the majority of this resistance, as most of the heat is generated by the mesh, which in this example has an electrical resistance over 100 times higher than the electrical contacts 32.

[0062] The substrate 34 is electrically insulating and, in this example, is formed from a polyimide sheet having a thickness of approximately 120 μm. The substrate is circular and has a diameter of 8 mm. The mesh is rectangular and has side lengths of 5 mm and 2 mm. These dimensions allow for the production of a complete system having a size and shape similar to that of a conventional cigarette or cigar. Another example of dimensions that has proven effective is a circular substrate with a diameter of 5 mm and a rectangular mesh of 1 mm by 4 mm.

[0063] Figure 7 illustrates an alternative exemplary heater assembly according to the present disclosure. The heater assembly of Figure 7 is the same as that shown in Figure 6, except that the mesh 36 is replaced by an array of parallel conductive filaments 37. The array of filaments 37 is formed from 304L stainless steel and has a diameter of approximately 16 μm. The substrate 34 and copper contacts 32 are as described with reference to Figure 6.

[0064] Figure 8 illustrates another alternative heater assembly according to the present disclosure. The heater assembly of Figure 8 is the same as that shown in Figure 7, except that in the assembly of Figure 8, a filament 37 is bonded directly to a substrate 34 and then contacts 32 are bonded onto the filament. The contacts 32 are separated from each other by insulating gaps 33 as before and are formed from copper foil approximately 30 μm thick. The same arrangement of substrate filaments and contacts can also be used for mesh-type heaters, as shown in Figure 6. Having the contacts as the outermost layer can be beneficial in providing reliable electrical contact with the power source.

[0065] Figure 9 illustrates an alternative heater assembly according to the present disclosure. The heater assembly of Figure 9 includes multiple heater filaments 38 integrally formed with electrical contacts 39. Both the filaments and electrical contacts are formed from stainless steel foil that has been etched to define the filaments 38. The contacts 39 are separated by gaps 33 except when connected by the filaments 38. The stainless steel foil is provided on a polyimide substrate 34. Again, the filaments 38 provide the majority of this resistance, so that the majority of the heat is generated by the filaments. In this example, the filaments 38 have an electrical resistance that is over 100 times higher than the electrical contacts 39.

[0066] In the cartridges shown in Figures 3, 4, and 5, the contacts 32 and filaments 36, 38 are located between the substrate layer 34 and the housing 24. However, the heater assembly can also be mounted inversely to the cartridge housing, with the polyimide substrate directly adjacent to the housing 24. Figure 10 illustrates this type of arrangement. Figure 10 shows a heater assembly including a stainless steel mesh 56 affixed to copper foil contacts 52. The copper contacts 52 are affixed to a polyimide substrate 54. An opening 55 is formed in the polyimide substrate 54. The polyimide substrate is welded to the cartridge housing 24. A capillary material 22 soaked in the aerosol-forming substrate fills the housing and extends through the opening to contact the mesh 55. The cartridge is received in the device body 11 and is shown held between an electrical connector 59 and the mouthpiece portion 12. In this embodiment, the electrical connector 59 is adapted to pierce the polyimide substrate 54, as shown, to make electrical connection with the contacts 52. The electrical connector is made with a sharpened end and is forced into contact with the heater assembly by a spring 57. The polyimide substrate may be pre-scored to ensure good electrical contact or may even provide openings so that drilling holes in the substrate is not necessary. The spring 57 also ensures that good electrical contact is maintained between the contacts 52 and the connector 59 regardless of the orientation of the system relative to gravity.

[0067] One means of ensuring the correct orientation of cartridge 20 within device cavity 18 has already been described with reference to FIGS. 5a and 5b. Positioning feature 25 can be formed as part of the molded cartridge housing 24 to ensure the correct orientation. However, it will become apparent that other methods of ensuring the correct orientation of the cartridge are possible. The possibilities for cartridge shape are nearly endless, particularly when the housing is injection molded. Once the desired internal volume of the cartridge is selected, the cartridge shape can be adapted to fit any cavity. FIG. 11a shows a bottom view of one possible cartridge housing 70, oriented in two possible orientations. Cartridge housing 70 includes two symmetrically positioned grooves 72. The grooves extend partially or entirely along the upper side of housing 70. Corresponding ribs (not shown) can be formed in the walls of the device cavity so that the cartridge can be received within the cavity in only two possible orientations. In the embodiment of FIG. 11a, it is also possible to have only a single rib within the cavity, such that one of grooves 72 is not filled with a rib and can be used as an airflow channel within the device. Of course, it is also possible to restrict the cartridge to a single orientation within the cavity by providing only a single groove within the housing. This is illustrated in Figure 11b, which shows a cartridge housing 74 with a single groove 76.

[0068] Although the described embodiment has a cartridge with a housing having a substantially circular cross section, it is of course possible to form the cartridge housing with other shapes, such as rectangular or triangular cross sections, which will ensure the desired orientation within a correspondingly shaped recess and ensure electrical connection between the device and the cartridge.

[0069] The capillary material 22 is advantageously oriented within the housing 24 to transport the liquid to the heater assembly 30. When the cartridge is assembled, the heater filaments 36, 37, and 38 can contact the capillary material 22, so that the aerosol-forming substrate can be directly transported to the mesh heater. Figure 12a is a detailed view of the filaments 36 of the heater assembly, showing the meniscus 40 of the liquid aerosol-forming substrate between the heater filaments 36. It can be seen that the aerosol-forming substrate contacts most of the surface of each filament, so that most of the heat generated by the heater assembly enters directly into the aerosol-forming substrate. In contrast, in conventional wick and coil heater assemblies, only a small portion of the heater wire contacts the aerosol-forming substrate. Figure 12b, similar to Figure 12a, is a detailed view showing an example of capillary material 27 extending into the gaps between the filaments 36. The capillary material 27 is the first capillary material shown in Figure 4. It has been found that by providing a capillary material comprising fine thread fibers extending into the interstices between the filaments 36, transport of liquid to the filaments can be ensured.

[0070] In use, the heater assembly operates by resistive heating. Under the control of the control electronics 16, electrical current is passed through the filaments 36, 37, 38, heating them to a desired temperature range. The mesh or array of filaments has a significantly higher electrical resistance than the electrical contacts 32 and electrical connector 19, so that high temperatures are localized to the filaments. The system may be configured to generate heat by supplying electrical current to the heater assembly in response to a user's puff, or may be configured to generate heat continuously while the device is in an "on" state. Different materials for the filaments may be appropriate for different systems. For example, in continuous heating systems, graphite filaments are appropriate because they have a relatively low specific heat capacity and are compatible with low-current heating. In systems operated by puffing, where heat is generated in short bursts using high-current pulses, stainless steel filaments, with their high specific heat capacity, may be more appropriate.

[0071] In a puff-activated system, the device may include a puff sensor configured to detect when a user draws air through the mouthpiece portion. The puff sensor (not shown) is connected to the control electronics 16, which is configured to supply current to the heater assembly 30 only when it is determined that the user is smoking on the device. Any suitable airflow sensor, such as a microphone, may be used as the puff sensor.

[0072] In a contemplated embodiment, changes in the resistivity of one or more of the filaments 36, 38, or the heater element as a whole, can be used to detect changes in the temperature of the heater element. This can be used to adjust the power supplied to the heater element so that it remains within a desired temperature range. Rapid temperature changes can also be used as a means of detecting changes in airflow through the heater element due to a user of the system smoking. One or more of the filaments can be dedicated temperature sensors and can be formed from a material with a suitable temperature coefficient of resistance for this purpose, such as iron-aluminum alloy, nickel-chromium, platinum, tungsten, or alloy wire.

[0073] The flow of air through the mouthpiece portion when the system is in use is shown in Figure 1d. The mouthpiece portion includes an internal baffle 17 that is integrally molded with the outer wall of the mouthpiece portion and that causes air, as it is drawn from inlet 13 to outlet 15, to flow over heater assembly 30 in the cartridge where the aerosol-forming substrate is vaporized. As the air passes over the heater assembly, the vaporized substrate becomes entrained in the airflow and cools to form an aerosol before exiting outlet 15. Thus, in use, the aerosol-forming substrate passes through the heater assembly by passing through the gaps between filaments 36, 37, 38 as it is vaporized.

[0074] There are numerous possibilities for heater assembly fabrication and materials. Figure 13a is a schematic diagram of a first method for fabricating a heater assembly. A roll of polyimide film 80 is provided with an array of openings 82 therein. The openings 82 can be formed by stamping. Strips of copper foil 84 are plated onto the polyimide film 80 between the openings. A ribbon of stainless steel mesh 86 is then clad onto the polyimide film 80, perpendicular to the copper foil strips, over the copper foil 84 and covering the openings 82. Individual heater assemblies 30 can then be cut or stamped around each opening 82. Each heater assembly 30 includes a section of copper foil that forms an electrical contact on the opposite side of the opening, and a strip of stainless steel mesh spans the opening from one section of copper to the other, as shown in Figure 6.

[0075] Figure 13b illustrates another possible manufacturing process. In the process of Figure 13b, a polyimide film 80 of the type used in the process of Figure 13a is clad with stainless steel foil 90. The polyimide film 80 has an array of openings 82 formed therein, which are covered by the stainless steel foil 90. The foil 90 is then etched to define filaments 38 across the openings 82 and to isolate contact portions on opposite sides of the openings. Individual heater assemblies 92 can then be cut or stamped around each opening 82, thereby providing a heater assembly of the type shown in Figure 9.

[0076] FIG. 13c illustrates a further alternative process. In the step of FIG. 13c, a graphite-based fiber 100 is first prepared. The graphite-based fiber 100 is suitable for use as a heater filament and includes a band of electrically resistive fiber adjacent to a band of relatively non-conductive fiber. These fiber bands are woven together with a band of relatively conductive fiber extending perpendicular to the resistive, non-conductive fiber. The fiber 100 is then bonded to a layer of polyimide film 80 having an array of openings 82, of the type described with reference to FIGS. 13a and 13b. Individual heater assemblies 102 can then be cut or stamped around each opening. Each heater assembly 102 includes a portion of the conductive fiber band opposite the opening and an electrically resistive fiber band spanning the opening.

[0077] The cartridge design shown in Figures 5a and 5b has several advantages. However, alternative cartridge designs using the same type of heater assembly are possible. Figure 14 illustrates an alternative cartridge design suitable for different airflow patterns through the system. In the embodiment shown in Figure 14, cartridge 108 is configured to be inserted into the device in the direction indicated by arrow 110. Cartridge 108 includes a housing 112 shaped like a half cylinder and open on one side. A heater assembly 114 is provided across the open side and is glued or welded to housing 112. Heater assembly 114 includes an electrically insulating substrate 116, such as polyimide, with an opening formed therein. A heater element, including a stainless steel mesh 118 and a pair of contact strips 120, is bonded to electrically insulating substrate 116 and spans the opening. Contact strips 120 are bent around housing 112 to form contact pads on the curved surface of the housing. The electrical contact pads are configured to contact corresponding contacts (not shown) within the aerosol generating device. The housing 112 is filled with a capillary material (not shown in Figure 14) that is immersed in an aerosol-forming substrate, as described with reference to the embodiment shown in Figures 1a to 1d.

[0078] The cartridge shown in Figure 14 is configured for airflow through heater assembly 114 in the direction opposite to that of arrow 110. Air is drawn into the system through an air inlet provided in the body of the device, through heater assembly 114, into the mouthpiece portion of the device (or cartridge), and into the user's mouth. Air drawn into the system can be directed in a direction parallel to mesh 118, for example, by appropriately positioning the air inlet.

[0079] Alternative embodiments of cartridge 108 are illustrated in FIGS. 15a and 15b. FIG. 15a further includes contact strips 120 extending along its length through gaps between the surface having mesh 118. FIG. 15b further includes contacts 120 that are approximately L-shaped. Both cartridge designs illustrated in FIGS. 15a and 15b can be used to provide a larger contact area, further ensuring easy contact with contacts 19, if desired. The strips 120 illustrated in FIG. 15a can also be configured to slide within contacts 19 configured with a rail configuration (not shown) for receiving strips 120, further positioning the cartridge. Such a rail-type configuration can advantageously provide for periodic cleaning of contacts 19, as insertion and removal of the cartridge has a cleaning effect due to the friction of the contacts sliding in and out of the rails.

[0080] Figure 16 illustrates yet another embodiment of an aerosol generation system with a fluid-permeable electric heater assembly. Figure 16 illustrates a system in which a heater assembly 30 is provided at the end of the cartridge 20 opposite the mouthpiece portion 12. Airflow enters the air inlet 1601 and passes by the assembly through the air outlet 1603 along a flow path 1605. Electrical contacts may be located at convenient locations. Such a configuration is advantageous because it allows for shorter electrical connections within the system.

[0081] Those skilled in the art will be able to devise other cartridge designs incorporating heater assemblies according to the present disclosure. For example, the cartridge may include a mouthpiece portion, may include multiple heater assemblies, and may have any desired shape. Moreover, heater assemblies according to the present disclosure can be used in other types of systems previously described, such as humidifiers, air fresheners, and other aerosol generating systems.

[0082] The above-described exemplary embodiments are illustrative and not limiting. In light of the exemplary embodiments discussed above, other embodiments consistent with the above exemplary embodiments will now be apparent to those skilled in the art. The present specification describes at least the following items. (1) An aerosol generating system comprising a fluid-permeable electric heater assembly, the heater assembly comprising: an electrically insulating substrate; an opening formed in the electrically insulating substrate; a heater element fixed to the electrically insulating substrate, the heater element including a plurality of conductive filaments extending across the opening and connected to first and second conductive contact portions, the first and second conductive contact portions being located on opposite sides of the opening, and the plurality of conductive filaments forming gaps, the gaps formed by the filaments having a width of 75 μm to 25 μm; An aerosol generating system, wherein the first and second conductive contact portions are configured to be capable of contacting an external power source. (2) The aerosol generating system described in (1), wherein the plurality of conductive filaments cover an area of ​​10% to 50% of the area of ​​the heater assembly. (3) An aerosol generating system described in (1) or (2), wherein the electrical resistance of the conductive filament is at least two orders of magnitude greater than the electrical resistance of the contact portion. (4) An aerosol generating system described in any one of (1) to (3), wherein the heater element has a first surface fixed to the electrically insulating substrate, and the first and second conductive contact portions are configured to be able to contact an external power source on a second surface of the heater element opposite the first surface. (5) An aerosol generating system according to any one of (1) to (4), wherein the conductive filament is in a substantially flat plane. (6) An aerosol generating system described in any one of (1) to (5), wherein the conductive filaments consist of an array of filaments arranged parallel to each other. (7) The area of ​​the conductive filament is 25 mm 2 The aerosol generating system according to any one of (1) to (6), wherein the aerosol generating system is less than 1000 kJ / kg. (8) An aerosol generating system described in any one of (1) to (7), wherein the first and second conductive contact portions include planar contact portions fixed to the conductive filament. (9) An aerosol generating system described in any of (1) to (8), wherein the heater assembly includes at least one filament made of a first material and at least one filament made of a second material different from the first material. (10) An aerosol generating system described in any one of (1) to (9), further comprising a liquid storage portion including a housing containing a liquid aerosol-forming substrate, and the heater assembly is fixed to the housing of the liquid storage portion. (11) An aerosol generating system according to any one of (1) to (10), wherein the system is an electrically operated smoking system. (12) A method of manufacturing a fluid-permeable electric heater assembly suitable for use in an aerosol generating system, comprising: providing an electrically insulating substrate; forming one or more openings in a substrate; providing at least two planar conductive contact portions on the substrate opposite said one or more openings; providing a plurality of conductive filaments on the substrate extending along one or more openings between the at least two planar conductive contact portions; The method, wherein the plurality of conductive filaments form gaps, and the gaps formed by the filaments have a width between 75 μm and 25 μm. (13) The method of (12), wherein the conductive filaments lie in a substantially flat plane. (14) The method according to (12) or (13), wherein the conductive filaments are an array of filaments arranged parallel to each other. (15) The area of ​​the conductive filament is 25 mm 2 The method according to (12), (13), or (14), wherein the concentration is less than 100 ppm.

Claims

1. 1. An aerosol generating system comprising a fluid-permeable electric heater assembly, said heater assembly comprising: an electrically insulating substrate; an opening formed in the electrically insulating substrate; a heater element fixed to the electrically insulating substrate, the heater element including a plurality of conductive filaments extending across the opening and connected to first and second conductive contact portions, the first and second conductive contact portions being located on opposite sides of the opening, and the plurality of conductive filaments forming gaps, the gaps formed by the filaments having a width of 75 μm to 25 μm; An aerosol generating system, wherein the first and second conductive contact portions are configured to be capable of contacting an external power source.

2. 2. The aerosol generating system of claim 1, wherein the plurality of conductive filaments cover an area of ​​10% to 50% of the area of ​​the heater assembly.

3. 3. The aerosol generating system according to claim 1, wherein the electrical resistance of the conductive filament is at least two orders of magnitude greater than the electrical resistance of the contact portion.

4. 4. The aerosol generating system of claim 1, wherein the heater element has a first surface fixed to the electrically insulating substrate, and the first and second conductive contact portions are configured to be in contact with an external power source on a second surface of the heater element opposite the first surface.

5. 5. The aerosol generating system according to claim 1, wherein the conductive filaments lie in a substantially flat plane.

6. 6. The aerosol generating system according to claim 1, wherein the conductive filaments consist of an array of filaments arranged parallel to one another.

7. The area of ​​the conductive filament is 25 mm 2 The aerosol generating system according to any one of claims 1 to 6, wherein the aerosol generating system is less than 10 ...

8. 8. The aerosol generating system of claim 1, wherein the first and second conductive contact portions comprise planar contact portions fixed to the conductive filament.

9. 9. The aerosol generation system of claim 1, wherein the heater assembly includes at least one filament made of a first material and at least one filament made of a second material different from the first material.

10. 10. The aerosol generating system of claim 1, further comprising a liquid storage portion including a housing containing a liquid aerosol-forming substrate, and wherein the heater assembly is fixed to the housing of the liquid storage portion.

11. An aerosol generating system according to any one of claims 1 to 10, wherein the system is an electrically operated smoking system.

12. 1. A method of manufacturing a fluid-permeable electric heater assembly suitable for use in an aerosol generating system, comprising: providing an electrically insulating substrate; forming one or more openings in a substrate; providing at least two planar conductive contact portions on the substrate opposite said one or more openings; providing a plurality of conductive filaments on the substrate extending along one or more openings between the at least two planar conductive contact portions; The method, wherein the plurality of conductive filaments form gaps, and the gaps formed by the filaments have a width between 75 μm and 25 μm.

13. The method of claim 12 , wherein the conductive filaments lie in a substantially flat plane.

14. 14. The method of claim 12 or 13, wherein the conductive filaments consist of an array of filaments arranged parallel to one another.

15. The area of ​​the conductive filament is 25 mm 2 15. The method of claim 12, 13 or 14, wherein the

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