Aerosol generating device with multi-layer insulation

Abstract

An aerosol generating device (100) comprising: a heater (106) for heating an aerosol-forming substrate; and a plurality of thermal insulation layers (108) disposed around at least a portion of the heater (106), the plurality of thermal insulation layers (108) comprising a heat spreader layer, the heat spreader layer comprising a housing (102) of the aerosol generating device (100). By spreading heat, the heat spreader layer prevents the formation of hot spots on the outer surface of the housing.

Description

Technical Field

[0001] The present disclosure relates to an aerosol generating device. Specifically, the present disclosure relates to, but is not exclusive to, a handheld electrically operated aerosol generating device configured to heat an aerosol forming substrate to generate an aerosol and deliver the aerosol into a user's mouth. The invention also relates to an aerosol generating system comprising an aerosol generating device and an aerosol generating article for use with the aerosol generating device.

Background Art

[0002] Aerosol generating devices in which an aerosol forming substrate is heated to produce an aerosol are known in the art. Such devices typically comprise a housing that holds a battery and control electronics, a portion or cavity for receiving or holding the aerosol forming substrate, an electric heater arranged to heat the aerosol forming substrate to generate an aerosol, and a mouthpiece for delivering the generated aerosol to the user.

[0003] The aerosol forming substrate can be a solid aerosol forming substrate, for example in the form of a tobacco rod or a tobacco plug. The solid aerosol forming substrate can be heated using a heater located externally or internally of the substrate. Alternatively, the aerosol forming substrate can be a liquid aerosol forming substrate. In this case, the heater typically comprises a heating element in the form of a coil of wire wound around an elongate wick that moves the liquid aerosol forming substrate from a liquid storage portion to the heating element.

[0004] A potential problem encountered with electrically operated aerosol generators is that the outer housing can become hot due to heat transfer from the heater to the outer housing. In particular, the area of ​​the outer housing directly above the heater can become especially hot, potentially creating so-called "hot spots" on the outer housing. Because the heater is closer to the outer housing in such devices, the problem is more pronounced in devices where the heater is located outside the aerosol-forming substrate. When the temperature of the outer housing rises above 50 degrees Celsius, the aerosol generator can become uncomfortable for the user to hold.

[0005] It would be desirable to provide an aerosol generator that reduces heat transfer from the heater to the device housing. It would also be desirable to provide an aerosol generator that remains comfortable to hold throughout the entire use of the device. [Overview of the project]

[0006] An aerosol generator is provided according to embodiments of the present disclosure. The aerosol generator may include a heater for heating an aerosol-forming substrate. The aerosol generator may include a plurality of insulating layers disposed around at least a portion of the heater. The plurality of insulating layers may include a heat spreader layer.

[0007] According to embodiments of the present disclosure, an aerosol generating apparatus is provided comprising a heater for heating an aerosol-forming substrate and a plurality of insulating layers disposed around at least a portion of the heater, wherein the plurality of insulating layers comprises a heat spreader layer.

[0008] As used herein, the terms “heat spreader” or “heat spreader layer” refer to a heat exchanger that transfers heat between a heat source and a heat sink or secondary heat exchanger, the surface area and geometric shape of which are generally larger than those of the heat source. The heat sink or secondary heat exchanger may be air or the ambient atmosphere, and the heat spreader may be, for example, a single piece or a sheet of material. In this case, the heat spreader functions by distributing heat across the entire surface area of ​​the sheet. The heat sink or secondary heat exchanger may be another object that is at a lower temperature than the heat source.

[0009] Advantageously, the heat spreader layer helps to diffuse heat across its entire surface area, reducing the formation of hot spots on the surface of the outer housing. The advantage of using multiple insulation layers, in contrast to a single insulation layer, is that different properties of different insulation layers can be leveraged. For example, in the arrangement described above, the heat spreader layer of the multiple insulation layers facilitates heat diffusion, while another insulation layer among the multiple insulation layers helps to reduce or slow down the transfer of heat to the outer housing of the device. This, therefore, improves the thermal insulation properties of the device compared to using only a single insulation layer. The aerosol generator is more comfortable to hold because the external temperature of the device is lower and the occurrence of hot spots is reduced. In addition, the space within a handheld, electrically operated aerosol generator for accommodating the insulation is limited. The inventors found that using multiple thinner insulation layers achieves improved thermal performance compared to using a single, thicker insulation layer.

[0010] A further advantage of reducing heat transfer to the outer housing of the aerosol generator is that more heat is retained by the device to heat the aerosol-forming substrate, leading to improved aerosol generation.

[0011] Multiple insulation layers may include a first insulation layer. Multiple insulation layers may include a second insulation layer. Advantageously, each of the first and second insulation layers helps reduce heat transfer from the heater to the outer housing of the aerosol generator via conduction and convection.

[0012] Multiple insulating layers may further comprise a radiant reflector layer. As used herein, the term “radiant reflector” refers to an object that reflects thermal radiation. For example, a radiant reflector may include a sheet of material that reflects thermal radiation. As a result, a radiant reflector reduces heat transfer by radiation by blocking or preventing a portion of the incident thermal radiation from passing through the reflector. Thus, a radiant reflector acts as a radiant reflective insulator.

[0013] Advantageously, the radiator reflector helps reduce heat transfer to the outer housing of the aerosol generator via radiation.

[0014] The radiant reflector is preferably located between the heater and the heater via a gap.

[0015] A radiant reflector layer may be placed between the first and second insulating layers. This arrangement prevents the radiant reflector from being in direct contact with the heater and avoids heat transfer via conduction through the radiant reflector. This also helps reduce the potential discoloration or degradation of the radiant reflector's reflective surface, which may be caused by the heater being in direct contact with the radiant reflector. In addition, this arrangement provides an object that reflects heat back, i.e., one of the first and second insulating layers placed inside the heater and the radiant reflector can receive the heat reflected from the radiant reflector.

[0016] The radiant reflector may be made from any suitable material having the ability to create a reflective surface. Suitable materials include, but are not limited to, metals, metal alloys, metallized polymers, glass, or ceramics.

[0017] Multiple insulation layers may be arranged around substantially all of the heater's outer surface to provide radial insulation, or they may surround substantially all of the heater's outer surface. The dimensions of the multiple insulation layers may be greater than the dimensions of the heater, so that the multiple insulation layers extend beyond the heater to provide a larger insulating surface. In particular, the length of the multiple insulation layers may be longer than the length of the heater.

[0018] At least one insulating layer may be provided at one end of the heater, or opposite it, i.e., across the longitudinal axis of the aerosol generator to provide axial insulation. At least one insulating layer may be provided between the heater and the control circuit of the aerosol generator. At least one insulating layer may comprise multiple insulating layers.

[0019] The heat spreader layer may be the outermost layer of multiple insulation layers. This arrangement allows any heat passing through the first and second insulation layers to diffuse across the entire area of ​​the heat spreader, which reduces the likelihood of hot spots forming.

[0020] The heat spreader layer may be placed between the first and second insulation layers. This arrangement allows any heat passing through either the first or second insulation layer to diffuse across the entire area of ​​the heat spreader, while the other insulation layer provides an additional layer of insulation to reduce heat transfer from the heat spreader. This arrangement reduces the likelihood of hot spots forming.

[0021] The heat spreader layer may be formed from a material having a thermal conductivity of at least 200 W / m·K, preferably at least 300 W / m·K, and more preferably at least 400 W / m·K. These ranges of thermal conductivity have been shown to be effective in the diffusion or dispersion of heat across the entire area of ​​the heat spreader layer.

[0022] The heat spreader layer may be anisotropic such that its thermal conductivity in a direction substantially parallel to the heat spreader layer is higher than its thermal conductivity in a direction substantially perpendicular to the heat spreader layer. This anisotropy means that more heat is diffused or dispersed across the heat spreader layer than through its thickness. Therefore, such anisotropic heat spreader layers are more efficient in heat diffusion or distribution and reduce the likelihood of hot spots compared to isotropic heat spreaders that conduct heat equally in all directions.

[0023] The thermal conductivity of the heat spreader layer in a direction substantially parallel to the heat spreader layer may be at least 700 W / m·K, preferably at least 1100 W / m·K, and more preferably at least 1500 W / m·K. The thermal conductivity in a direction substantially parallel to the heat spreader layer may be 700 W / m·K to 2000 W / m·K, preferably 1100 W / m·K to 2000 W / m·K, and more preferably 1500 W / m·K to 2000 W / m·K. These ranges of thermal conductivity have been shown to be effective in the diffusion or dispersion of heat across the entire area of ​​the heat spreader layer.

[0024] The thermal conductivity of the heat spreader layer in a direction substantially perpendicular to the heat spreader layer may be 50 W / m·K or less, preferably 40 W / m·K or less, and more preferably 30 W / m·K or less.

[0025] The heat spreader layer may be made from any suitable material having the ability to effectively dissipate heat. Suitable materials include, but are not limited to, metals and metal alloys such as aluminum and copper, as well as graphite. Preferably, the heat spreader layer may contain graphite. More preferably, the heat spreader layer may contain a pyrolytic graphite sheet. Graphite has been shown to be a particularly effective heat diffusing material.

[0026] The heat spreader layer may include the housing of the aerosol generator. Such an arrangement avoids the need for a separate heat spreader layer and utilizes the housing of the aerosol generator to dissipate heat. The outer housing dissipates the heat received from the first and second insulating layers over at least a portion of the area of the outer housing where heat can be dissipated to the ambient air.

[0027] As another method, the aerosol generator may further include a housing in addition to the heat spreader layer, and this housing performs an additional heat dissipation function.

[0028] The housing may be formed from a material having a thermal conductivity of at least 200 W / m·K, preferably at least 300 W / m·K, more preferably at least 400 W / m·K. These ranges of thermal conductivity have been found to be effective in the diffusion or dispersion of heat over the entire surface area of the outer housing.

[0029] The housing may be made from any suitable material having the ability to effectively dissipate heat. Suitable materials include, but are not limited to, metals and metal alloys such as aluminum and copper.

[0030] The thermal conductivity of the first insulating layer may be 0.050 W / m·K or less, preferably 0.040 W / m·K or less, more preferably 0.030 W / m·K or less. The thermal conductivity of the second insulating layer may be 0.050 W / m·K or less, preferably 0.040 W / m·K or less, more preferably 0.030 W / m·K or less. These ranges of thermal conductivity have been found to be effective in reducing or slowing down heat transfer through the first and second insulating layers.

[0031] The first insulating layer may have an operating temperature above 200 degrees Celsius, preferably above 250 degrees Celsius.

[0032] The second insulating layer may have an operating temperature above 200 degrees Celsius, preferably above 250 degrees Celsius.

[0033] As used herein, the term “operating temperature” refers to the temperature at which the material can be used without any noticeable degradation or loss of mechanical or thermal properties.

[0034] The first insulating layer may be made from any suitable material having the required thermal conductivity. Suitable materials include, but are not limited to, polymers, ceramics, or glass. The material may also be formed as particles, beads, films, sheets, foams, fibers, aerogels, or blocks. For example, the first insulating layer may be made from polyimide aerogel, polyimide foam, ceramic paper, aramid fiber paper, polyimide film, silicone foam or sponge, polymer aerogel, rubber, or aerogel particles, or a combination thereof. The first insulating layer may be gaseous. The first insulating layer may be air.

[0035] The second insulating layer may be made from any suitable material having the required thermal conductivity. Suitable materials include, but are not limited to, polymers, ceramics, or glass. The material may also be formed as particles, beads, films, sheets, foams, fibers, aerogels, or blocks. For example, the first insulating layer may be made from polyimide aerogel, polyimide foam, ceramic paper, aramid fiber paper, polyimide film, silicone foam or sponge, polymer aerogel, rubber, or aerogel particles, or a combination thereof. The second insulating layer may be gaseous. The second insulating layer may be air.

[0036] The overall thickness of the multiple insulation layers within the aerosol generator may be 2 mm or less, and preferably 1.75 mm or less. This overall thickness allows the multiple insulation layers to fit within a handheld, electrically operated aerosol generator where space is limited. Such a thickness also avoids the need to increase the dimensions of the aerosol generator to accommodate the insulation layers.

[0037] The first insulation layer may have an incompressible thickness of 3.0 mm or less, preferably 2.5 mm or less. The first insulation layer may have an incompressible thickness of about 0.125 mm to about 2.5 mm, preferably about 1 mm to about 2.5 mm, more preferably about 1.5 mm to about 2.5 mm. This has been found to be an appropriate range of thickness for the first insulation layer to effectively reduce or slow down heat transfer.

[0038] The first insulation layer may include a film. The first insulation layer may have a thickness of about 0.010 mm to about 1 mm, preferably about 0.020 mm to about 0.75 mm.

[0039] The second insulation layer may have an incompressible thickness of 3.0 mm or less, preferably 2.5 mm or less. The second insulation layer may have an incompressible thickness of about 0.125 mm to about 2.5 mm, preferably about 1 mm to about 2.5 mm, and more preferably about 1.5 mm to about 2.5 mm. This has been found to be an appropriate range of thickness for the second insulation layer to effectively reduce or slow down heat transfer.

[0040] The second insulation layer may include a film. The second insulation layer may have a thickness of about 0.010 mm to about 1 mm, preferably about 0.020 mm to about 0.75 mm.

[0041] The heater may comprise one or more electric heating elements. The electric heating elements may include an electrically resistive material. Suitable electrically resistive materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilide), carbon, graphite, metals, alloys, and composite materials made of ceramic and metallic materials. Such composite materials may include doped or undoped ceramics. An example of a suitable doped ceramic is doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable metal alloys include stainless steel, nickel-containing alloys, cobalt-containing alloys, chromium-containing alloys, aluminum-containing alloys, titanium-containing alloys, zirconium-containing alloys, hafnium-containing alloys, niobium-containing alloys, molybdenum-containing alloys, tantalum-containing alloys, tungsten-containing alloys, tin-containing alloys, gallium-containing alloys, manganese-containing alloys, gold-containing alloys, and iron-containing alloys, as well as nickel, iron, cobalt, stainless steel-based superalloys, Timetal®, Kanthal®, and other iron-chromium-aluminum alloys, and iron-manganese-aluminum alloys. In composite materials, the electrically resistive material may be embedded in an insulating material, sealed in an insulating material, or coated with an insulating material, depending on the required energy transfer dynamics and external physicochemical properties. Alternatively, the electric heater may include one or more infrared heating elements, photonic sources, or induction heating elements.

[0042] One or more heating elements may be formed using a metal or metal alloy having a clear relationship between temperature and resistivity. Heating elements formed in this manner may be used both for heating the heating element and for monitoring the heating element's temperature during operation.

[0043] The heating element may be placed within or on a rigid carrier material or substrate. The heating element may be formed as a track on a suitable insulating material such as ceramic or glass. The heating element may be sandwiched between two insulating materials.

[0044] The heater may include an internal heater, an external heater, or both an internal and an external heater, where "internal" and "external" refer to positions relative to the aerosol-forming substrate.

[0045] The internal heater may take any suitable form. For example, the internal heater may take the form of a heating blade. Alternatively, the internal heater may take the form of a casing or substrate having different conductive parts or electrically resistant metal tubes. Alternatively, the internal heater may be one or more heating needles or rods extending through the center of the aerosol-forming substrate. Other alternatives include heating wires or filaments, such as Ni-Cr (nickel-chromium), platinum, gold, silver, tungsten, or alloy wires or heating plates.

[0046] The external heater may take any suitable form. For example, the external heater may take the form of one or more flexible heating foils on a dielectric substrate such as polyimide. The flexible heating foils can be shaped to fit around the periphery of the substrate receiving cavity. Alternatively, the external heater may take the form of a heating coil, one or more metal grids, a flexible printed circuit board, a molded circuit component (MID), a ceramic heater, a flexible carbon fiber heater, or it may be formed on a substrate of a suitable shape using a coating technique such as plasma deposition.

[0047] The heater may be a tubular heater disposed to receive an aerosol-forming substrate or aerosol-generating article within the internal space of the tube. The tubular heater may comprise a tubular support or substrate having a heating element disposed on or within the support or substrate. The heating element may be disposed on the inner surface of the tube or on the outer surface of the tube. In one embodiment, the heater may include an aluminum oxide ceramic tube having a Kanthal® heating element surrounding the outer cylindrical surface of the tube.

[0048] The aerosol generator may further include a heating chamber for containing or receiving an aerosol generating article or an aerosol forming substrate. The heater may be located inside or outside the heating chamber, or may be part of the heating chamber.

[0049] The aerosol generating device may further include a cavity for receiving an aerosol-forming substrate or an aerosol-generating article.

[0050] The aerosol generator may include a barrier to separate one or more of the multiple insulating layers from the airflow path for transporting the aerosol to the user. The barrier may be lined with a cavity for receiving the aerosol-forming substrate or aerosol-generating article.

[0051] The aerosol generator may further include a power source or supply for powering the internal and external heaters. The power source may be any suitable power source, such as a DC voltage source. In one embodiment, the power source is a lithium-ion battery. Alternatively, the power source may be a nickel-metal hydride battery, a nickel-cadmium battery, or a lithium-based battery, such as a lithium-cobalt, lithium iron phosphate, or lithium polymer battery.

[0052] In one embodiment, the aerosol generator further includes a sensor that detects an airflow indicating that a user is inhaling smoke, which enables the activation of an electric heater based on the smoke inhalation, or improved energy management of the electric heater. The sensor may be based on any of the following: mechanical, electromechanical, optical, opticomechanical, or microelectromechanical systems (MEMS). In that embodiment, the sensor may be connected to a power source, and the system is configured to activate the electric heater when the sensor detects that a user is inhaling smoke. In an alternative embodiment, the aerosol generator further includes a manually operable switch for the user to initiate smoke inhalation or to enable a longer-lasting experience.

[0053] The aerosol generator is preferably a handheld aerosol generator that is comfortable for the user to hold between the fingers of one hand. The aerosol generator may be substantially cylindrical in shape. The aerosol generator may have a polygonal cross-section and a protruding button formed on one of its faces. In this embodiment, the outer diameter of the aerosol generator may be about 12.7 mm to 13.65 mm when measured from one flat face to the opposite flat face, about 13.4 mm to 14.2 mm when measured from one edge to the opposite edge (i.e., from the intersection of two faces on one side of the aerosol generator to the corresponding intersection on the other side), and about 14.2 mm to 15 mm when measured from the top of the button to the flat face on the opposite bottom. The length of the aerosol generator may be about 70 mm to 120 mm.

[0054] The aerosol generator may further include a control circuit configured to control the supply of power to the heater assembly. The control circuit may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), or other electronic circuit capable of providing control. The control circuit may include further electronic components. For example, in some embodiments, the control circuit may include a sensor element, a switch element, or a display element. Power may be supplied to the heater assembly continuously after the device is started, or intermittently (e.g., with each smoke extraction). Power may be supplied to the heater assembly in the form of current pulses, for example, by pulse width modulation (PWM).

[0055] The housing of the aerosol generator may be elongated. The housing may comprise a two-part housing, a first housing component containing a power supply and control circuit, and a second housing component containing a heater and cavity for receiving an aerosol-forming substrate or aerosol-generating article. The housing may contain any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of these materials, or thermoplastic resins suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably lightweight and not brittle.

[0056] According to embodiments of this disclosure, an aerosol generating system is provided which comprises an aerosol generating device according to any of the embodiments described above. The aerosol generating system may also comprise an aerosol generating article containing an aerosol forming substrate.

[0057] According to embodiments of this disclosure, an aerosol generating system is provided, comprising an aerosol generating device according to any of the embodiments described above, and an aerosol generating article containing an aerosol forming substrate.

[0058] As used herein, the term “aerosol-generating article” refers to an article comprising an aerosol-forming substrate that releases volatile compounds capable of forming aerosols when heated within an aerosol generator. The aerosol-generating article is separated from the aerosol generator and is also configured to be combined with the aerosol generator for heating the aerosol-generating article.

[0059] The terms “distal,” “upstream,” “proximal,” and “downstream” are used to describe the relative locations of components or parts of components of aerosol generating devices and aerosol generating articles. The aerosol generating articles and devices according to this disclosure have a proximal end through which aerosol exits for delivery to the user during use, and a distal end on the opposite side. The proximal end of the aerosol generating article and device may also be called the mouth end. During use, the user inhales the proximal end of the aerosol generating article or device to inhale the aerosol generated by the aerosol generating article or device. The terms upstream and downstream relate to the direction of movement of the aerosol through the aerosol generating article when the user inhales the proximal end. The proximal end of the aerosol generating article is downstream of the distal end of the aerosol generating article. The proximal end of the aerosol generating article may also be called the downstream end of the aerosol generating article, and the distal end of the aerosol generating article may also be called the upstream end of the aerosol generating article.

[0060] In one embodiment, the aerosol generating article may consist solely of an aerosol-forming substrate. During operation, the aerosol-forming substrate may be completely contained within the aerosol generator. In this case, the user may inhale the mouthpiece of the aerosol generator. The mouthpiece may be any part of the aerosol generator that is positioned in the user's mouth to directly inhale the aerosol generated by the aerosol generating article or the aerosol generator. The aerosol is delivered to the user's mouth through the mouthpiece.

[0061] In alternative embodiments, the aerosol generating article may comprise further components, and during operation, the aerosol generating article containing the aerosol-forming substrate may be partially contained within the aerosol generating device. In this case, the user may directly inhale the aerosol generating article or the mouthpiece of the aerosol generating article.

[0062] The aerosol-generating article may be substantially cylindrical in shape. The aerosol-generating article may be substantially elongated. The aerosol-forming substrate may be substantially cylindrical in shape. The aerosol-forming substrate may be substantially elongated.

[0063] The aerosol generating article may have an overall length of approximately 30 mm to approximately 100 mm. The aerosol generating article may have an outer diameter of approximately 5 mm to approximately 12 mm. The aerosol forming substrate may have a length of approximately 10 mm to approximately 18 mm. Furthermore, the diameter of the aerosol forming substrate may be approximately 5 mm to approximately 12 mm. The aerosol generating article may be equipped with a filter plug. The filter plug may be located at the downstream end of the aerosol generating article. The filter plug may be a cellulose acetate filter plug. In one embodiment, the filter plug is approximately 7 mm long, but may have a length of approximately 5 mm to approximately 12 mm.

[0064] In one embodiment, the aerosol generating article may have a total length of approximately 45 mm. The aerosol generating article may have an outer diameter of approximately 7.3 mm, or it may have an outer diameter of approximately 7.0 mm to approximately 7.4 mm. Furthermore, the aerosol forming substrate may have a length of approximately 12 mm. Alternatively, the aerosol forming substrate may have a length of approximately 16 mm. The aerosol generating article may be provided with an outer paper wrapper. Furthermore, the aerosol generating article may be provided with a separation section between the aerosol forming substrate and the filter plug. The separation section may be approximately 21 mm or approximately 26 mm, or it may be in the range of approximately 5 mm to approximately 28 mm. Separation may be provided by a hollow tube. The hollow tube may be made from cardboard or cellulose acetate.

[0065] The aerosol-forming substrate may be a solid aerosol-forming substrate. Alternatively, the aerosol-forming substrate may comprise both solid and liquid components. The aerosol-forming substrate may contain a tobacco-containing material that includes volatile tobacco-flavored compounds released from the substrate upon heating. Alternatively, the aerosol-forming substrate may contain a non-tobacco material. The aerosol-forming substrate may further comprise aerosol-forming bodies. Suitable examples of aerosol-forming bodies include glycerin and propylene glycol.

[0066] If the aerosol-forming substrate is a solid aerosol-forming substrate, it may contain one or more of the following: herb leaves, tobacco leaves, tobacco vein fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and puffed tobacco, and may be in the form of, for example, powder, granules, pellets, fragments, spaghetti, slivers, or sheets. The solid aerosol-forming substrate may be in loose form or may be provided in a suitable container or cartridge. Optionally, the solid aerosol-forming substrate may contain additional tobacco or non-tobacco volatile flavor compounds that are released upon heating of the substrate. The solid aerosol-forming substrate may also contain, for example, capsules containing additional tobacco or non-tobacco volatile flavor compounds, which may melt during heating of the solid aerosol-forming substrate.

[0067] As used herein, “homogenized tobacco” refers to a material formed by agglomerating particulate tobacco. Homogenized tobacco may be in the form of a sheet. Homogenized tobacco material may have an aerosol-forming content of more than 5% by dry weight. Alternatively, homogenized tobacco material may have an aerosol-forming content of 5% to 30% by dry weight. Homogenized tobacco material sheets may be formed by agglomerating particulate tobacco obtained by crushing or otherwise finely grinding one or both of the leaf blades and / or stems of tobacco leaves. Alternatively, or additionally, homogenized tobacco material sheets may include one or more of the following: tobacco dust, tobacco fines, and other particulate tobacco by-products formed during tobacco processing, handling, and shipping. The homogenized tobacco material sheet may contain one or more inherent binders (i.e., endogenous tobacco binders), one or more exogenous binders (i.e., exogenous tobacco binders), or a combination thereof, to help aggregate particulate tobacco. Alternatively, or additionally, the homogenized tobacco material sheet may contain other additives, including but not limited to tobacco and non-tobacco fibers, aerosol formizers, wetting agents, plasticizers, flavoring agents, fillers, aqueous and non-aqueous solvents, and combinations thereof.

[0068] In a particularly preferred embodiment, the aerosol-forming substrate comprises an aggregate of crimped sheets of homogenized tobacco material. As used herein, the term “crimped sheet” means a sheet having a plurality of substantially parallel ridges or undulations. When the aerosol-generating article is assembled, it is preferable that the substantially parallel ridges or undulations extend along or parallel to the longitudinal axis of the aerosol-generating article. This is advantageous as it facilitates the assembly of crimped sheets of homogenized tobacco material to form the aerosol-forming substrate. However, naturally, the crimped sheets of homogenized tobacco material to be included in the aerosol-generating article may, in an alternative or additional manner, have a plurality of substantially parallel ridges or undulations that are arranged at acute or obtuse angles with respect to the longitudinal axis of the aerosol-generating article when the aerosol-generating article is assembled. In a particular embodiment, the aerosol-forming substrate may comprise an aggregate of sheets of homogenized tobacco material that are substantially uniformly textured across substantially its entire surface. For example, the aerosol-forming substrate may include an aggregate of crumpled sheets of homogenized tobacco material, each containing a plurality of substantially parallel ridges or undulations substantially evenly spaced across the width of the sheet.

[0069] Optionally, the solid aerosol-forming substrate may be provided on or embedded within a thermally stable carrier. The carrier may take the form of a powder, granules, pellets, fragments, spaghetti, strips, or sheets. Alternatively, the carrier may be a tubular carrier having a thin layer of solid substrate deposited on its inner surface, its outer surface, or both its inner and outer surfaces. Such tubular carriers may be formed from, for example, paper or paper-like material, nonwoven carbon fiber mat, low-mass coarse mesh metal screen, or perforated metal foil, or any other thermally stable polymer matrix.

[0070] The solid aerosol-forming substrate may be deposited on the surface of a carrier, for example, in the form of a sheet, foam, gel, or slurry. The solid aerosol-forming substrate may be deposited over the entire surface of the carrier, or alternatively, in a pattern to provide non-uniform flavor delivery during use.

[0071] Although the above refers to a solid aerosol-forming substrate, it will be apparent to those skilled in the art that other forms of aerosol-forming substrates may be used in other embodiments. For example, the aerosol-forming substrate may be a liquid aerosol-forming substrate. If a liquid aerosol-forming substrate is provided, the aerosol generator preferably includes means for holding the liquid. For example, the liquid aerosol-forming substrate may be held in a container or liquid storage section. Alternatively, or additionally, the liquid aerosol-forming substrate may be absorbed into a porous carrier material. The porous carrier material may be made of any suitable absorbent plug or body, such as foamed metal or plastic material, polypropylene, terylene, nylon fiber, or ceramic. The liquid aerosol-forming substrate may be held in the porous carrier material before use of the aerosol generator, or, alternatively, the liquid aerosol-forming substrate material may be released into the porous carrier material during or immediately before use. For example, the liquid aerosol-forming substrate may be provided in a capsule. The capsule shell preferably melts upon heating, releasing the liquid aerosol-forming substrate into the porous carrier material. The capsules may optionally contain a solid combined with a liquid.

[0072] Alternatively, the carrier may be a nonwoven fiber or bundle of fibers in which tobacco components are incorporated. The nonwoven fiber or bundle of fibers may include, for example, carbon fibers, natural cellulose fibers, or cellulose derivative fibers.

[0073] Features described in relation to one of the above embodiments may be equally applicable to other embodiments of the present disclosure.

[0074] The present invention is defined in the claims. However, a non-exclusive list of non-limiting embodiments is provided below. One or more features of these embodiments may be combined with one or more features of other embodiments, forms, or aspects described herein.

[0075] Example 1: An aerosol generator comprising a heater for heating an aerosol-forming substrate and at least one insulating layer disposed around at least a portion of the heater.

[0076] Example 2: An aerosol generator comprising a heating chamber for heating an aerosol-forming substrate, and at least one insulating layer disposed around at least a portion of the heating chamber.

[0077] Example 3: An aerosol generator according to Example 1 or Example 2, wherein the aerosol generator comprises a plurality of insulating layers arranged around at least a portion of the heater.

[0078] Example 4: An aerosol generator according to any of the preceding embodiments, wherein at least one or more insulating layers include a heat spreader layer.

[0079] Example 5: An aerosol generator according to Example 3 or Example 4, wherein multiple insulating layers further comprise a first insulating layer.

[0080] Example 6: Aerosol generator according to Example 5, wherein multiple insulating layers further include a second insulating layer.

[0081] Example 7: An aerosol generator according to any of Examples 3 to 6, wherein multiple insulating layers further comprise a radiant reflector layer.

[0082] Example 8: An aerosol generator according to Example 7, wherein a radiant reflector layer is disposed between the first and second insulating layers.

[0083] Example 9: An aerosol generator according to any of Examples 4 to 8, wherein the heat spreader layer is the outermost layer of multiple insulating layers.

[0084] Example 10: An aerosol generator according to any of Examples 6 to 9, wherein a heat spreader layer is disposed between a first insulation layer and a second insulation layer.

[0085] Example 11: An aerosol generator according to any of Examples 4 to 10, wherein the heat spreader layer is formed from a material having a thermal conductivity of at least 200 W / m·K.

[0086] Example 12: An aerosol generator according to any of Examples 4 to 11, wherein the heat spreader layer may be anisotropic, thereby resulting in a higher thermal conductivity in a direction substantially parallel to the heat spreader layer compared to a thermal conductivity in a direction substantially perpendicular to the heat spreader layer.

[0087] Example 13: An aerosol generator according to Example 12, wherein the thermal conductivity in a direction substantially parallel to the heat spreader layer is at least 700 W / m·K.

[0088] Example 14: An aerosol generator according to any of Examples 4 to 13, wherein the heat spreader layer contains graphite.

[0089] Example 15: An aerosol generator according to any of Examples 4 to 13, wherein the heat spreader layer comprises the housing of the aerosol generator.

[0090] Example 16: An aerosol generator according to any of the preceding embodiments, further comprising a housing, the housing being formed from a material having a thermal conductivity of at least 200 W / m·K.

[0091] Example 17: An aerosol generator according to any of Examples 6 to 16, wherein the thermal conductivity of the first and second insulating layers is 0.050 W / m·K or less, preferably 0.040 W / m·K or less, and more preferably 0.030 W / m·K or less.

[0092] Example 18: An aerosol generator according to any of Examples 3 to 17, wherein the overall thickness of the multiple insulation layers inside the aerosol generator is less than 2 mm.

[0093] Example 19: An aerosol generating device according to any of the preceding embodiments, wherein the heater is a tubular heater and is arranged to receive an aerosol generating article within the internal space of the tube.

[0094] Example 20: An aerosol generator according to Example 19, wherein the tubular heater comprises a tubular substrate having a heating element disposed on or inside the substrate.

[0095] Example 21: An aerosol generator according to Example 19 or Example 20, wherein the heating element is placed on the outer surface of the tube.

[0096] Example 22: An aerosol generator according to any of the preceding embodiments, further comprising a cavity for receiving an aerosol-generating article.

[0097] Example 23: An aerosol generator according to any of Examples 3 to 22, further comprising one or more of the multiple insulation layers as a barrier for separating the aerosol from the airflow path for transporting the aerosol to the user.

[0098] Example 24: An aerosol generator according to Example 23, wherein the barrier lines a cavity for receiving an aerosol-generating article.

[0099] Example 25: An aerosol generating system comprising an aerosol generating device according to any of Examples 1 to 24 and an aerosol generating article containing an aerosol forming substrate.

[0100] Here, we will further describe the examples with reference to the following figures. [Brief explanation of the drawing]

[0101] [Figure 1] Figure 1 is a schematic partial cross-section of a part of an aerosol generator according to one embodiment showing an electric heater and multilayer insulation. [Figure 2] Figure 2 is a schematic diagram of the interior of an aerosol generator according to another embodiment, showing an aerosol-generating article received inside the device. [Figure 3] Figure 3A is an enlarged cross-section of the area labeled A in Figure 2, showing the heater and a multi-layer insulation arrangement according to one embodiment. Figure 3B is an enlarged cross-section of the area labeled A in Figure 2, showing the heater and a multi-layer insulation arrangement according to another embodiment. [Figure 4] Figures 4A and 4B show two different test configurations for testing the thermal insulation performance of an aerosol generator. [Modes for carrying out the invention]

[0102] Figure 1 shows a portion of an aerosol generator 10, which has an electric heater 12 and several insulating layers 14 disposed between the electric heater 12 and a housing 16. The electric heater is tubular and has an internal space having a diameter D for receiving an aerosol generating article (not shown) of a similar diameter. Thus, the electric heater is positioned externally to the aerosol-forming substrate in the aerosol-forming article. The tubular structure of the electric heater 12 is made of aluminum oxide ceramic, and a heating element 18 made of Kanthal® surrounds its external cylindrical surface in a meandering or undulating manner. The heating element 18 is disposed at one end of the electric heater 12 and has two ends 18a and 18b connected to electrical leads (not shown) for connecting the electric heater 12 to a power source (not shown) via a control circuit (not shown). The electric heater 12 is heated to a temperature of approximately 210 degrees Celsius and is configured to heat the aerosol-forming substrate to generate an aerosol.

[0103] Figure 1 shows a general structure for multiple thermal insulation layers 14 according to this disclosure, comprising a first thermal insulation layer 20, a radiant reflector 22, a second thermal insulation layer 24, and a heat spreader layer 26. At least one of the layers, for example, the radiant reflector 22, is optional and may be omitted in certain embodiments, as will be discussed below. Furthermore, the heat spreader layer 26 may be replaced by another component of the aerosol generator 10, for example, an outer housing 16 in one of the embodiments discussed below.

[0104] The first insulation layer 20 has a high operating temperature (i.e., approximately 250 degrees Celsius or higher) so that it can withstand the operating temperature of the heater 12. In addition to being an insulating material, the first insulation layer 20 also acts as an electrical insulator to prevent short circuits in the connections of any electrical components that may come into contact. Thin film insulators such as Kapton® tape may be used. Alternatively, thicker foam or aerogel insulators may be used.

[0105] The radiant reflector 22 is positioned adjacent to and outside the first insulating layer 20, but may be positioned differently. The radiant reflector 22 is generally formed from a thin metal foil or metallized material having a reflective surface facing the heater 12. It is important that the radiant reflector 22 is separated from the heater 12 by a gap, for example, air or an insulating layer, so that there is space within which thermal radiation can be reflected. Furthermore, if the radiant reflector 22 were positioned in contact with the heater, heat would be transferred by conduction through the radiant reflector 22, reducing its effectiveness and creating a risk that the reflective surface of the radiant reflector 22 would be discolored or otherwise degraded by the heater 12.

[0106] The second insulation layer 24 is located adjacent to and outside the radiant reflector 22, but may be positioned differently. The second insulation layer 20 has a high operating temperature (i.e., approximately 200 degrees Celsius or higher). Since the second insulation layer 24 is located further away from the heater 12 and is at least partially protected by the first insulation layer 20, the operating temperature of the second insulation layer 24 does not need to be as high as that of the first insulation layer 20. A thin film insulator such as an aerogel film may be used, or alternatively, a thicker foam or aerogel insulator may be used.

[0107] The heat spreader layer 26 is positioned adjacent to and on the outside of the second insulation layer 24, although it may be positioned differently. Typically, the heat spreader layer 26 is made from a sheet or foil of a material having a high thermal conductivity (i.e., at least 200 W / m·K). However, in a preferred embodiment, an anisotropic heat spreader layer 26 such as a pyrolytic graphite sheet is used. This has a relatively high thermal conductivity (i.e., greater than 700 W / m·K) in the direction parallel to the plane of the sheet (i.e., the xy direction) and a relatively low thermal conductivity (i.e., less than 30 W / m·K) in the direction perpendicular to the sheet (i.e., the z direction). As a result, the heat spreader layer 26 effectively diffuses or disperses heat within the layer, i.e., in the direction parallel to the heat spreader layer 26, but reduces heat transfer through the thickness of the layer, i.e., in the direction perpendicular to the heat spreader layer 26. By diffusing heat, the heat spreader layer 26 helps reduce the risk of hot spots forming on the outer surface of the housing 16. By reducing heat transfer through the thickness of the layer, the heat spreader layer 26 effectively helps insulate the housing from the heat generated by the heater 12.

[0108] The housing 16 is positioned adjacent to and on the outside of the heat spreader layer 26. Multiple insulating layers 14 reduce heat transfer from the heater 12 to the outer housing 16, thereby reducing the possibility of the outer housing, or any part thereof, becoming excessively hot (i.e., exceeding a temperature of 50 degrees Celsius), and helping to maintain the housing 16 at a temperature that is not uncomfortable for the user to hold. In this embodiment, the housing 16 is made from polyetheretherketone (PEEK), which is itself a moderate insulator. However, the housing 16 can be made from a material with a higher thermal conductivity so that the outer housing 16 also acts as a heat spreader.

[0109] Figure 2 shows the interior of the aerosol generator 100 and the aerosol generating article 200 received inside the aerosol generator 100. Together, the aerosol generator 100 and the aerosol generating article 200 form an aerosol generating system. In Figure 2, the aerosol generator 100 is shown in a simplified form. Specifically, the elements of the aerosol generator 100 are not drawn to actual size. Furthermore, elements not relevant to understanding this embodiment have been omitted.

[0110] The aerosol generator 100 comprises a housing 102 containing a power supply 103, an electric heater 106, a control circuit 105, and multiple insulation layers 108. The power supply 103 is a battery, which in this embodiment is a rechargeable lithium-ion battery. The control circuit 105 is connected to both the power supply 103 and the heater 106 and controls the supply of electrical energy from the power supply 103 to the electric heater 106 to regulate the temperature of the electric heater 106.

[0111] The housing has an opening 104 at the proximal or oral end of the aerosol generator 100 through which the aerosol generating article 200 is received. The aerosol generator 100 and the multiple insulation layers 108 are shown in cross-section in Figure 2. The multiple insulation layers 108 surround the heater 106 and the cavity 110 in which the aerosol generating article 200 is received within the housing 102. Specifically, the multiple insulation layers 108 surround both the heater 106 and the cavity 110 to reduce heat transfer to the housing 102, and are arranged across the distal end of the cavity 110 to reduce heat transfer to the control circuit 105. The multiple insulation layers 108 can have various different arrangements of insulation layers, two of which are described below with reference to Figures 3A and 3B.

[0112] The heater 106 is tubular and has the same design as the heater in Figure 1. When the aerosol generating article 200 is received into the aerosol generating device 100, it passes through the internal space of the tubular heater 106.

[0113] The aerosol generating article 200 comprises an end plug 202, an aerosol forming substrate 204, a hollow tube 206, a mouthpiece filter 208, and a paper wrapper 210. The aerosol forming substrate 204 includes a plug made of tobacco material or tobacco-based material. When the aerosol generating article 200 is fully received into the aerosol generating device 100, the aerosol forming substrate 204 is positioned within the heater 106, so that the heater 106 can heat the aerosol forming substrate 204 to form an aerosol. The end plug 202 and the mouthpiece filter 208 are made of cellulose acetate fibers.

[0114] The aerosol generator 100 may further include a sensor (not shown) for detecting the presence of an aerosol generating article 200, a user interface (not shown) such as a button for activating the heater 106, and a display or indicator (not shown) for presenting information to the user, such as remaining battery power, heating status, and error messages.

[0115] Figures 3A and 3B are enlarged schematic diagrams of the area labeled A in Figure 2, showing a cross-section through a portion of the aerosol generator 100, including the heater 106, multiple insulation layers 108, and the housing 102. Figures 3A and 3B are simplified, and the elements of the aerosol generator 100 are not depicted to actual size.

[0116] Furthermore, some of the insulation layers within the multiple insulation layers 108 are compressible, since they are formed from foam, aerogel, or another compressible structure. This is beneficial because it allows the multiple insulation layers 108 to adapt to changes in the profile within the aerosol generator 100. As can be seen in Figure 2, the internal profile along the aerosol generator changes, for example, as the aerosol generating article 200 moves in and out through the electric heater 106, and as the housing tapers towards its mouth end. Any compressible material within the multiple insulation layers 108 will be compressed where the contour narrows. However, the inventors have found that the amount of compression involved does not have any perceptible adverse effect on the thermal performance of the insulation layers. In the following discussion, any reference to the thickness of the material is relative to its uncompressible thickness.

[0117] Figure 3A shows a first arrangement 108a of multiple insulation layers for use in the aerosol generator 100 of Figure 2. The first arrangement 108a of multiple insulation layers comprises a first insulation layer 120, a heat spreader layer 122, and a second insulation layer 124.

[0118] The first insulation layer 120 includes a polyimide aerogel sleeve having a thickness of 2.5 mm. Suitable polyimide aerogel sleeves include, but are not limited to, sleeves made from Airloy X116 polyimide aerogel manufactured by Aerogel Technologies in Boston, Massachusetts, USA.

[0119] The heat spreader layer 122 comprises a pyrolytic graphite sheet having a thickness of 25 micrometers. A suitable pyrolytic graphite sheet is, but is not limited to, part number EYGA121803KV supplied by Panasonic in Newark, New Jersey, USA.

[0120] The second insulation layer 124 comprises a polymer aerogel having a thickness of 1 mm. Suitable polymer aerogels include, but are not limited to, Aerozero polymer films or blocks supplied by Blueshift Materials in Spencer, Massachusetts, USA.

[0121] Figure 3B shows a second arrangement 108b of multiple insulation layers for use in the aerosol generator 100 of Figure 2. The second arrangement 108b of multiple insulation layers comprises a first insulation layer 130, a radiant reflector 132, a second insulation layer 134, and a housing 102 that forms a heat spreader layer.

[0122] The first insulation layer 130 includes a polyimide film having a thickness of 25 micrometers. Suitable polyimide films include, but are not limited to, Kapton® Tape supplied by DuPont in Wilmington, Delaware, USA.

[0123] The radiator reflector 132 comprises aluminum foil having a thickness of 0.016 mm. Any suitable aluminum foil of the required thickness may be used.

[0124] The second insulation layer 134 comprises a polyimide foam having a thickness of 2.5 mm. Suitable polyimide foams include, but are not limited to, Intek® PFI-1120 polyimide foam supplied by Trelleborg in Trelleborg, Sweden.

[0125] To form a heat spreader layer, the polymer-based housing 102 of the aerosol generator in Figure 2 is replaced with a tubular aluminum housing having an inner diameter of 17 mm and an outer diameter of 18.5 mm. Aluminum has a higher thermal conductivity than plastic and helps to dissipate heat across the entire surface area of ​​the housing. Any suitable aluminum housing may be used.

[0126] test To determine the thermal performance of using multiple insulating layers compared to using only a single layer, test examples of each of the arrangements in Figures 3A and 3B were prepared and tested in the aerosol generator 100 in Figure 2. As a control, further test examples containing only a single insulating layer were prepared and also tested in the aerosol generator 100 in Figure 2.

[0127] To measure the temperature, thermocouples were used and attached to the relevant test points on the aerosol generator 100, as described below for each test. The heater 106 was powered by an external laboratory power supply. The aerosol generator was held horizontally and stationary and tested at an ambient temperature of approximately 23–25 degrees Celsius.

[0128] As can be seen in Figures 4A and 4B, an empty paper tube 300 without an aerosol-forming substrate, filter, or plug was used in the test instead of the aerosol-generating article 200 in Figure 2. This was done to simulate a worst-case scenario in which some heat is dissipated within the aerosol generated by the aerosol-forming substrate 204, so that all the heat is dissipated into the apparatus 100.

[0129] The aerosol generator 100 and the aerosol generating article 200 had the dimensions shown in Table 1. [Table 1]

[0130] The following testing methods were used. • Heat the heater to 210 degrees Celsius as quickly as possible without exceeding the 12-watt power limit. • Control the heater temperature to maintain it at 210 degrees Celsius for 6 minutes. • Record power and temperature at the 6-minute mark.

[0131] Test Example 1 Test Example 1 had the structure of the first arrangement 108a of multiple insulation layers shown in Figure 3A. The multiple insulation layers 108a circumferentially surrounded the cavity 110 containing the heater 106 and the paper tube 300. At the distal end of the cavity 110, a single layer of polyimide aerogel identical to the first insulation layer 120 in Figure 3A was placed in the gap between the paper tube and the control circuit 105.

[0132] For control, further test examples were prepared using a single insulating layer equivalent to the first insulating layer 120 in Figure 3A, namely, a sleeve fabricated from Airloy X116 polyimide aerogel manufactured by Aerogel Technologies in Boston, Massachusetts, USA, with a thickness of 2.5 mm.

[0133] As can be seen in Figure 4A, thermocouples were attached to the following points. • Point X1 is located on the outside of the paper tube, inside the heater 106. • Point X2 is located on the outside of the housing 102, above the midpoint of the heater 106. • Point X3 is located on the outside of housing 102, to the left of point X2 (towards the proximal end of the device). • Point X4 is located on the outside of housing 102, to the right of point X2 (towards the distal end of the device). • Point X5, where the electrical leads from heater 106 are connected to control circuit 105.

[0134] Measurements X3 and X4 were performed to evaluate the performance of the thermal graphite sheet as a heat spreader and its ability to dissipate heat to reduce hot spots.

[0135] The results of the test in Test Example 1 are shown in Table 2 below. [Table 2]

[0136] The results show that the multi-layer insulation in Test Example 1 improved thermal insulation performance compared to the single-layer insulation of the control. As can be seen from temperature measurements X2, X3, and X4, the temperature on the outside of the housing was considerably lower for Test Example 1 than for the control. Each of these temperatures for Test Example 1 is below the comfort threshold temperature of 50 degrees Celsius. The deviation between temperature measurements X2, X3, and X4 in Test Example 1 was also smaller compared to the control, indicating that the heat spreader layer is effective in diffusing heat across its entire surface area to reduce the formation of hot spots.

[0137] Furthermore, the power required to maintain the heater at 210 degrees Celsius in Test Example 1 is lower compared to the control, indicating that the multilayer configuration helps improve the system's efficiency. In addition, the temperature X5 is lower in Test Example 1, indicating that the configuration helps protect the control circuit from the heat generated by the heater 106.

[0138] Test Example 2 Test example 2 had the structure of the first arrangement 108b of multiple insulation layers shown in Figure 3B. The multiple insulation layers 108b circumferentially surrounded the cavity 110 containing the heater 106 and paper tube 300. As discussed above with respect to Figure 3B, the polymer housing 102 of the aerosol generator in Figure 2 is replaced with an aluminum housing to provide a heat spreader layer.

[0139] For control, further test examples were prepared with a single insulating layer equivalent to the second insulating layer 134 in Figure 3B, i.e., made from Intek® PFI-1120 polyimide foam supplied by Trelleborg, Sweden, and having a sleeve with a thickness of 2.5 mm. The control was used with a standard polymer housing 102 of the aerosol generator in Figure 2.

[0140] As can be seen in Figure 4B, thermocouples were attached to the following points. • Point Y1 is located on the outside of the paper tube, inside the heater 106. • Point Y2 is located on the outside of the housing 102, above the midpoint of the heater 106. • Point Y3 is where the electrical leads from heater 106 are connected to control circuit 105.

[0141] The results of the test in Test Example 2 are shown in Table 3 below. [Table 3]

[0142] The results show that the multi-layer insulation in Test Example 2 improved the thermal insulation performance compared to the single-layer insulation of the control. As can be seen from temperature measurement Y2, the temperature on the outside of the housing is considerably lower for Test Example 2 than for the control. Temperature measurement Y2 for Test Example 2 is well below the comfort threshold temperature of 50 degrees Celsius. Temperature measurement Y2 also shows that the use of housing materials with high thermal conductivity (i.e., above 200 W / m·K) can provide effective thermal diffusion.

[0143] Test Example 3 A third test example was also prepared. Test example 3 has the same structure as test example 1 in terms of multiple insulation layers, namely, the first arrangement 108a of multiple insulation layers as shown in Figure 3A. However, in test example 3, the polymer housing 102 of the aerosol generator in Figure 2 is replaced with a copper tubular housing having a diameter of 15 mm, providing an additional heat spreader layer to the pyrolysis graphite sheet heat spreader layer 122 in Figure 3A. The temperature was measured using the thermocouple arrangement shown in Figure 4B.

[0144] The results of the test in Test Example 3 are shown in Table 4 below. [Table 4]

[0145] As can be seen from Table 4, the temperature on the outside of the housing in Test Example 3 (temperature measurement Y2) is 7 degrees Celsius lower than the equivalent temperature in Test Example 1 (temperature measurement X2). This therefore indicates that the use of housing materials with high thermal conductivity (i.e., greater than 200 W / m·K) can further improve the thermal diffusion performance of the aerosol generator.

Claims

1. An aerosol generating device, comprising: An outer housing; a heater for heating the aerosol-forming substrate; a plurality of layers of insulation disposed about at least a portion of the heater; a first insulating layer; a second insulating layer; a radiation reflector layer, the radiation reflector layer being disposed between a first insulating layer and a second insulating layer; a heat spreader layer; The aerosol generating device, wherein the heat spreader layer comprises an outer housing of the aerosol generating device.

2. 2. The aerosol generating device of claim 1, wherein the heat spreader layer is formed from a material having a thermal conductivity of at least 200 W / m·K.

3. An aerosol generating device as described in either claim 1 or 2, wherein the heat spreader layer may be anisotropic, such that the thermal conductivity in a direction substantially parallel to the heat spreader layer is higher than the thermal conductivity in a direction substantially perpendicular to the heat spreader layer.

4. 4. The aerosol generating device according to claim 1, wherein the heat spreader layer comprises graphite.

5. 5. An aerosol generating device according to claim 1, wherein the total thickness of the layers of thermal insulation within the aerosol generating device is less than 2 mm.

6. 6. An aerosol generating device according to claim 1, further comprising a cavity for receiving an aerosol-generating article.

7. The aerosol generating device of claim 6 , wherein the cavity comprises a heater.

8. 8. The aerosol generating device of claim 6 or 7, wherein the plurality of layers of thermal insulation are further disposed across a distal end of the cavity.

9. 9. An aerosol generating device according to claim 6, wherein the plurality of thermal insulation layers surround substantially the entire cavity.

10. An aerosol generating device as described in any one of claims 1 to 9, further comprising a power source and control circuit configured to control the supply of power to the heater, and at least a portion of the multiple insulation layers are disposed between the heater and the control circuit.

11. 11. An aerosol generating device according to claim 1, wherein the heater is a tubular heater having an interior space arranged to receive an aerosol-generating article.

12. 12. The aerosol generating device of claim 11, wherein the tubular heater comprises a tubular substrate having a heating element disposed on or within the tubular substrate.

13. 13. The aerosol generating device of claim 12, wherein the heating element is disposed on an exterior surface of the tubular substrate.

14. 14. The aerosol generating device of claim 1, further comprising a barrier for separating one or more of the plurality of layers of insulation from an airflow path for transporting the aerosol to a user.

15. 1. An aerosol generation system comprising: An aerosol generating device according to any one of claims 1 to 14, an aerosol-generating article comprising an aerosol-forming substrate;

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