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 that includes a heater assembly suitable for vaporizing a liquid, in particular 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, which vaporizes the liquid within the capillary material. The capillary material is typically held in an airflow path such that air is drawn through the wick and entrained in the vapor. The vapor is then cooled to form an aerosol.

[0003] This type of system is effective at generating aerosols and is 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 robust. It is further desirable to provide a heater assembly that is more efficient than prior heater assemblies for aerosol generating systems. Summary of the Invention

[0005] In one embodiment, an aerosol generating system is provided with a fluid-permeable electric heater assembly, the heater assembly including an electrically insulating substrate, an aperture 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 extending across the aperture and connected to first and second conductive contact portions, the first and second conductive contact portions disposed opposite each other on opposite sides of the aperture, where 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 non-woven 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 a rigid housing and is impermeable to fluids. As used herein, "rigid housing" means a free-standing housing. The rigid housing of the liquid storage portion 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 an aerosol generating system with this type of heater assembly has several advantages over conventional wick and coil arrangements: A heater element comprising a mesh or array of filaments provides a large 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 parts of the aerosol generating system, in particular forming part of a removable cartridge. 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 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 robust construction.

[0012] The conductive filaments may define gaps between the filaments, the gaps may have a width of 10 μm to 100 μm. The filaments preferably induce capillary action within the gaps such that liquid to be vaporized in use 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 160-600 mesh US (±10%) (i.e., 160-600 filaments per inch (±10%)). The gap width is preferably 75 μm-25 μm. The mesh open area ratio, which is the ratio of the gap area to the total mesh area, is preferably 25-56%. The mesh may be formed using different types of weaves or lattice structures. Alternatively, the conductive filaments 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 from 8 μm to 100 μm, preferably from 8 μm to 50 μm, and more preferably from 8 μm to 39 μm.

[0016] The area of ​​the mesh, array or fibre of conductive filaments can be as small as 25 mm 2 Preferably, the conductive filament mesh, array or fiber has a thickness of less than 10 mm, allowing for incorporation into a handheld system. The conductive filament mesh, array or fiber may be rectangular, for example, with dimensions of 5 mm by 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, etc.), 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, and nickel, iron, cobalt, 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 mesh, array or fiber of conductive filaments of the heater element is preferably 0.3-4 ohms. More preferably, the electrical resistance of the mesh, array or fiber of conductive filaments is 0.5-3 ohms, and more preferably about 1 ohm. The electrical resistance of the mesh, array or fiber of conductive filaments is preferably at least one order of magnitude greater than the electrical resistance of the contacts, and more preferably at least two orders of magnitude greater. This ensures that heat generated by passing electrical current from the heater element is localized to the mesh or array of conductive filaments. When the power source of the system is a battery, it is advantageous for the heater element to have a low overall resistance. Minimizing wasted losses between the electrical contacts and the mesh or filament is also desirable to minimize wasted power losses. A low resistance, high current system allows high power to be delivered to the heater element. This allows the heater element to heat the conductive filaments quickly to the desired temperature.

[0019] The first and second conductive contact portions may be secured directly to the conductive filament. The contact portions may be disposed between the conductive filament and an electrically insulating substrate. For example, the contact portions may be formed from copper foil plated onto an insulating substrate. The contact portions may 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 a plurality of filaments between the two contact portions.

[0021] The heater assembly may comprise 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 may be beneficial for electrical or mechanical reasons. For example, one or more of the filaments may be formed from a material that has a resistance that varies significantly with temperature, such as an iron-aluminum alloy. This allows a measurement of the resistance of the filament to be used to determine temperature or temperature change. This may be used in a smoke detection system to control the heater temperature to keep the heater within a desired temperature range.

[0022] The electrically insulating substrate may comprise any suitable material, but is preferably a material 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, including 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 is substantially resistant to thermal decomposition at the operating temperatures of the system, facilitating the formation of a dense and stable aerosol in use. Suitable aerosol-forming agents are well known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, and glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of mono-, di-, or polycarboxylic acids (such as 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 flavorants.

[0025] The capillary material may have a fibrous or spongy structure. The capillary material preferably comprises a bundle of capillaries. For example, the capillary material may comprise a number 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 number 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, fibrous materials made of 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 be used with 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 enable 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 gap between the filaments. The heater assembly may draw the liquid aerosol-forming substrate into the gap 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 pyrolysis temperature and a second capillary material in contact with the first capillary material but not the heater element has a lower pyrolysis temperature. The first capillary material effectively acts as a spacer separating the heater element from the second capillary material so that the second capillary material is not exposed to temperatures above its pyrolysis temperature. As used herein, "pyrolysis temperature" means 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 loading 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 in the liquid reservoir from an opposite side of the conductive filament such that the airflow passing through the conductive filament is mixed into the vaporized liquid aerosol-forming substrate.

[0030] The system may further comprise an electrical circuit connected to the heater element and to the power supply, the electrical circuit configured to monitor an 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 in dependence 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, a microcontroller, or an application specific integrated circuit chip (ASIC) or other electronic circuitry with control capabilities. The electrical circuitry may comprise further 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 activation of the system, 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 within the body of the housing (typically a power source such as a lithium ion 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 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 generation of aerosol for a period of approximately six minutes, or a multiple of six minutes, corresponding to the typical time it takes to smoke one conventional cigarette. 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 storage and heater assembly are provided in the cartridge, and where 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 coupled and separated 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 generation system. The aerosol generation 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 aperture formed in the electrically insulating substrate, and a heater element having a first surface across the aperture 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 disposed opposite one another on opposite sides of the aperture, where 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 a substrate opposite 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 the other aspects of the invention, in particular features described in relation to the heater assembly of the first aspect of the invention may be applied to the heater assembly of the second aspect of the invention as well.

[0040] As used herein, "electrically conductive" means a resistivity of 1×10 -4 As used herein, "insulating" means made of a material with a resistivity of 1×10 4 This means that it is made from a material with a resistance of Ωm or higher.Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: [Brief description 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. [Diagram 2] FIG. 2 is a schematic diagram of a clasp mechanism for the mouthpiece portion of the system of FIG. [Diagram 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] FIG. 5a is a perspective view of the underside of the cartridge of 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 in the cartridge shown in FIG. [Figure 8] FIG. 8 is a detailed view of a further alternative heater assembly that may be used in 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] FIG. 11a illustrates several cartridge housing shapes that may be used to ensure proper alignment of the cartridge within the device. [Figure 11b] FIG. 11b illustrates several 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 capillary material extending between the filaments. [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 of the liquid reservoir incorporating a heater assembly. [Figure 15a] FIG. 15a illustrates a further alternative embodiment of a liquid storage portion into which a heater assembly is incorporated. [Figure 15b] FIG. 15b illustrates a further alternative embodiment of a liquid storage portion into which a heater assembly is incorporated. [Figure 16] FIG. 16 illustrates an alternative embodiment of airflow and cartridge orientation with an aerosol generating device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] Figures la-ld are schematic diagrams of an aerosol generation system including a cartridge according to an embodiment of the present invention. Figure la 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 cavity 18 in the device. The cartridge 20 should be replaceable by a user when the aerosol-forming substrate provided in the cartridge is depleted. Figure 1a shows the cartridge 20 immediately 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 a conventional cigar or cigarette. The device 10 includes a body 11 and a mouthpiece portion 12. The body 11 includes 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 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 placed in the open position to allow insertion and removal of a cartridge 20, and is placed in the closed position when the system is used to generate aerosol, as described below. The mouthpiece portion includes a number of air inlets 13 and outlets 15. In use, a user draws or inhales the outlets to draw air from the air inlets 13, through the mouthpiece portion, to the outlets 15, and then into the user's mouth or lungs. An internal baffle 17 is provided to force air flow through the cartridges 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 for providing electrical connection between the control electronics 16 and the battery 14 and corresponding electrical contacts on the cartridge 20.

[0046] Figure 1b shows the system of Figure 1a with the cartridge inserted into cavity 18 and cover 26 removed. In this position, the electrical connector bears 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 the mouthpiece portion 12 in a closed position. The mouthpiece portion 12 is held in the closed position by a clasp feature as shown diagrammatically in FIG. 2. FIG. 2 illustrates a body 11 and a mouthpiece portion 12 connected by a hinged connection 21. The mouthpiece portion 12 includes inwardly extending teeth 8. When the mouthpiece portion is in the closed position, the teeth 8 engage with a clasp 6 on the body of the device. The clasp 6 is biased by a bias spring 5 into engagement with the teeth 8. A button 4 is secured to the clasp 6. The button 4 can be pressed by a user against the action of the bias spring 5 to release the teeth 8 from the 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 for holding the mouthpiece in the closed position may be used, such as a snap-on or magnetic closure.

[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 in 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 cavity 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 in the cavity and ensure a good electrical connection. The threaded connection may extend less than a 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] 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 includes a capillary material 22 immersed in a liquid aerosol-forming substrate. In this example, the aerosol-forming substrate includes 39 percent by weight glycerin, 39 percent by weight propylene glycol, 20 percent by weight water and flavorings, and 2 percent by weight nicotine. The capillary material is a material that actively transports liquid from one end to the other and may be manufactured 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 gaps 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 a user to grasp the cover when removing it. It will be apparent to one of ordinary skill 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 may also be used, including heat sealing or ultrasonic welding, 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 capillary material and the second capillary material hold a liquid aerosol-forming substrate. The first capillary material 27, which contacts the heater element, has a higher pyrolysis temperature (at least 160° C. or higher, such as about 250° C.) than the second capillary material 28. The first capillary material 27 effectively acts 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 is such 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 an element containing glass fiber, and the second capillary material is a polymer such as a suitable capillary material. Exemplary suitable capillary materials include the capillary materials 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 such 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 such that when the cartridge is fully inserted into the cavity 18, the exposed portions of the contacts 32 contact the electrical connector 19. Tabs provided on the sides of the cover 26 for a user to grip the cover when peeling are clearly shown. FIG. 5a also illustrates a locating feature 25 formed in the base of the cartridge to ensure proper orientation of the cartridge in the cavity of the device. The locating 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 locating 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 materials 22, 27, 28 into the housing 24. A volume of liquid aerosol-forming substrate is then introduced into the housing 24, soaking the capillary material. The heater assembly 30 is then pressed into the open end of the housing and secured to the housing 24 by gluing, welding, heat sealing, ultrasonic welding, or other methods that will become apparent to those skilled in the art herein. 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 it is 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 prior to filling the housing with the aerosol-forming substrate, and introduce the aerosol-forming substrate into the housing 24. In that case, the heater assembly may 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 comprises a mesh formed from 304L stainless steel with a mesh size of about 400 mesh US (about 400 filaments per inch). The filaments have a diameter of about 16 μm. The mesh is formed of copper foil with a thickness of about 30 μm, connected to electrical contacts 32 separated from each other by gaps 33. The electrical contacts 32 are provided on a polyimide substrate 34 with a thickness of about 120 μm. The filaments forming the mesh define gaps between the filaments. In this example, the gaps have a width of about 37 μm, although larger or smaller gaps may be used. Using a mesh of these approximate dimensions, a meniscus of the aerosol-forming substrate is formed within the gaps, and the mesh of the heater assembly draws the aerosol-forming substrate by capillary action. The open area of ​​the mesh, i.e., the ratio of the area of ​​the gaps to the total area of ​​the mesh, is advantageously between 25 and 56%. The total resistance of the heater assembly is about 1 ohm. The mesh provides most 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 is formed from a polyimide sheet having a thickness of about 120 μm in this example. 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 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 about 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, the filament 37 is bonded directly to the substrate 34 and then the 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 about 30 μm thick. The same arrangement of substrate filaments and contacts can also be used for a mesh type heater, as shown in Figure 6. Having the contacts as the outermost layer can be beneficial in providing reliable electrical contact with a power source.

[0065] FIG. 9 illustrates an alternative heater assembly according to the present disclosure. The heater assembly of FIG. 9 includes a plurality of heater filaments 38 formed integrally with electrical contacts 39. Both the filaments and electrical contacts are formed from stainless steel foil that is etched to define the filaments 38. The contacts 39 are separated by gaps 33 except when joined 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, such 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 cartridge 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 the housing 24. Figure 10 illustrates this type of arrangement. Figure 10 shows a heater assembly including a stainless steel mesh 56 secured to copper foil contacts 52. The copper contacts 52 are secured 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. The 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 body 11 of the device and is shown held between the 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, for making electrical connection with the contacts 52. The electrical connector is made with sharpened ends and is forced into contact with the heater assembly by 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 required. Spring 57 also ensures that good electrical contact between contacts 52 and connector 59 is maintained regardless of the orientation of the system relative to gravity.

[0067] One means of ensuring the correct orientation of the cartridge 20 in the cavity 18 of the device has already been described with reference to Figures 5a and 5b. The locating portion 25 can be formed as part of the molded cartridge housing 24 to ensure the correct orientation. However, it will become apparent that other ways of ensuring the correct orientation of the cartridge are possible. There are almost infinite possibilities for the shape of the cartridge, especially if the housing is injection molded. Once the desired internal volume of the cartridge has been selected, the cartridge shape can be adapted to suit any cavity. Figure 11a shows a bottom view of one possible cartridge housing 70, oriented in two possible orientations. The cartridge housing 70 includes two symmetrically arranged grooves 72. The grooves extend partially or entirely on the upper side of the housing 70. Corresponding ribs (not shown) can be formed in the walls of the cavity of the device so that the cartridge can be received in the cavity in only two possible orientations. In the embodiment of Figure 11a, it is also conceivable to have only a single rib in the cavity, such that one of the grooves 72 is not filled by a rib and can be used as an air flow channel in the device. Of course, it is possible to restrict the cartridge to a single orientation within the cavity by providing only a single groove in 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 a rectangular or triangular cross section, that 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 carry the liquid to the heater assembly 30. When the cartridge is assembled, the heater filaments 36, 37, 38 can be in contact with the capillary material 22 so that the aerosol-forming substrate can be directly carried to the mesh heater. FIG. 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, such that most of the heat generated by the heater assembly goes directly into the aerosol-forming substrate. In contrast, in a conventional wick and coil heater assembly, only a small portion of the heater wire contacts the aerosol-forming substrate. FIG. 12b is a detailed view similar to FIG. 12a, showing an example of the capillary material 27 extending into the gap between the filaments 36. The capillary material 27 is the first capillary material shown in FIG. 4. It has been found that by providing a capillary material comprising fine thread fibres 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. Electric current is passed through the filaments 36, 37, 38 under the control of the control electronics 16, heating the filaments to within the desired temperature range. The mesh or array of filaments has a significantly higher electrical resistance than the electrical contacts 32 and electrical connectors 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 a continuous heating system, a graphite filament is appropriate because it has a relatively low specific heat capacity and is compatible with low current heating. In a system operated by puffing, where heat is generated in short bursts using high current pulses, a stainless steel filament with a 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 in 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 may be used as the puff sensor, such as a microphone.

[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, may be used to detect changes in the temperature of the heater element. This may be used to adjust the power supplied to the heater element so that it remains within a desired temperature range. Rapid temperature changes may also be used as a means of detecting changes in airflow through the heater element due to smoking by a user of the system. The one or more filaments may be dedicated temperature sensors and may be formed from materials with suitable temperature coefficients of resistance for this purpose, such as iron aluminum alloys, nickel chromium, platinum, tungsten or alloy wires.

[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 which is integrally molded with the outer wall of the mouthpiece portion and which causes air to flow over a heater assembly 30 in the cartridge where the aerosol-forming substrate is vaporized as it is drawn from the inlet 13 to the outlet 15. As the air passes over the heater assembly, the vaporized substrate is entrained in the airflow and cooled to form an aerosol before exiting the outlet 15. Thus, in use, the aerosol-forming substrate passes through the heater assembly by passing through the gaps between the 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 of 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 over the copper foil 84 and over the openings 82 in a direction perpendicular to the copper foil strips. 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 entire 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 the filaments 38 across the openings 82 and to isolate the contact portions on opposite sides of the openings. Individual heater assemblies 92 can then be cut or stamped around each opening 82. This provides a heater assembly of the type shown in Figure 9.

[0076] FIG. 13c illustrates a further alternative process. In the process 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 fibers adjacent to a band of relatively non-conductive fibers. These bands of fibers are woven together with a band of relatively conductive fibers that run at right angles to the resistive, non-conductive fibers. The fiber 100 is then bonded to a layer of polyimide film 80 having an array of apertures 82 of the type described with reference to FIGS. 13a and 13b. Individual heater assemblies 102 can then be cut or stamped around each aperture. Each heater assembly 102 includes a portion of the conductive fiber band opposite the aperture and an electrically resistive fiber band across the aperture.

[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 patterns of airflow through the system. In the embodiment shown in Figure 14, the cartridge 108 is configured to be inserted into the device in the direction indicated by arrow 110. The 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 the housing 112. The 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 the electrically insulating substrate 116 and spans the opening. The contact strips 120 are bent around the 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) in the aerosol generating device. The housing 112 is filled with a capillary material (not shown in FIG. 14) that is immersed in an aerosol-forming substrate, as described with reference to the embodiment shown in FIGS. 1a-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 may be directed in a parallel direction along mesh 118, for example, by appropriately positioning the air inlet.

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

[0080] Fig. 16 illustrates yet another embodiment of an aerosol generation system with a fluid-permeable electric heater assembly. Fig. 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 any convenient location. Such a configuration is advantageous as it allows for shorter electrical connections within the system.

[0081] One of ordinary skill in the art could 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, the heater assemblies according to the present disclosure may be used in other types of systems previously described, including humidifiers, air fresheners, and other aerosol generating systems.

[0082] The above 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 of ordinary skill in the art.

Claims

1. 1. An aerosol generation 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 secured to said electrically insulating substrate, said heater element including a plurality of conductive filaments extending across said opening and connected to first and second conductive contact portions, said first and second conductive contact portions being located on opposite sides of said opening, and said plurality of conductive filaments forming gaps, said gaps formed by said filaments having a width between 75 μm and 25 μm; An aerosol generation system, wherein the first and second conductive contact portions are configured to be contactable with an external power source.

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

3. 3. The aerosol generating system of 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 contactable 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 each other.

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. An aerosol generating system according to 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 comprises 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, the heater assembly being secured 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 wherein 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 planar 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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