Heater assembly with microporous aerogel insulation

Abstract

The present invention relates to a heater assembly (10) for an aerosol-generating device. The heater assembly (10) includes a heating chamber (12) for heating an aerosol-forming substrate. The heater assembly (10) further includes a heater casing (16). The heater casing (16) is disposed around the heating chamber (12). The heater casing (16) is further disposed radially spaced from the heating chamber (12). The heater casing (16) further includes an airtight space. The airtight space includes a microporous insulating material (32). The microporous insulating material (32) includes an aerogel. The present invention further relates to an aerosol-generating device including the heater assembly (10), and to an aerosol-generating system including the aerosol-generating device and an aerosol-forming substrate.

Description

[Technical Field]

[0001] The present disclosure relates to a heater assembly for an aerosol generating device.The present disclosure further relates to an aerosol generating device.The present disclosure further relates to an aerosol generating system comprising an aerosol generating device and an aerosol-forming substrate. [Background technology]

[0002] It is known to provide an aerosol-generating device for generating an inhalable vapor. Such a device may heat an aerosol-forming substrate contained in an aerosol-generating article without burning the aerosol-forming substrate. The aerosol-generating article may have a rod shape for insertion into a heating chamber of the aerosol-generating device. A heating element is typically disposed in or around the heating chamber to heat the aerosol-forming substrate after the aerosol-generating article is inserted into the heating chamber of the aerosol-generating device.

[0003] Heat generated by the heating element may inadvertently dissipate from the heating chamber. Heat may dissipate to the environment or to other components of the aerosol-generating system. Heat may inadvertently dissipate from the heating chamber by free air convection. Heat may inadvertently dissipate from the heating chamber by radiation. Heat may inadvertently dissipate from the heating chamber by thermal conduction through components of the aerosol-generating device. Heat may inadvertently dissipate from the heating chamber by thermal conduction through components of the aerosol-generating article, for example, through the aerosol-forming substrate. Heat dissipation from the heating chamber may cause heating of components of the device that are not intended to be heated. For example, the housing of the device that the user grips may become uncomfortably hot. Heat dissipation from the heating chamber may cause heat loss within the heating chamber. Heat loss within the heating chamber may result in less efficient heating. An excessive amount of energy may be required to heat the heating chamber to the desired temperature.

[0004] It would be desirable to have an aerosol generating device that can reduce heat loss from the heated chamber. It would be desirable to insulate the heated chamber from other components of the aerosol generating device. It would be desirable to have an aerosol generating device that can reduce heating of the outer housing of the device that is gripped by the user. It would be desirable to have an aerosol generating device that can provide effective insulation. It would be desirable to have an aerosol generating device that can provide insulation at low manufacturing costs. It would be desirable to have an aerosol generating device that can provide lightweight insulation. It would be desirable to have an aerosol generating device that can have improved insulation. It would be desirable to have an aerosol generating device that can have a reduced outer diameter of the heater casing. It would be desirable to have an aerosol generating device that can have more compact device dimensions. Summary of the Invention

[0005] According to one embodiment of the present invention, there is provided a heater assembly for an aerosol-generating device. The heater assembly may include a heating chamber for heating an aerosol-forming substrate. The heater assembly may include a heater casing. The heater casing may be disposed around the heating chamber. The heater casing may be disposed radially spaced from the heating chamber. The heater casing may include an airtight space. The airtight space may include a microporous insulating material. The microporous insulating material may include an aerogel.

[0006] According to one embodiment of the present invention, there is provided a heater assembly for an aerosol-generating device. The heater assembly includes a heating chamber for heating an aerosol-forming substrate. The heater assembly further includes a heater casing. The heater casing is disposed around the heating chamber. The heater casing is further disposed radially spaced apart from the heating chamber. The heater casing further includes an airtight space. The airtight space includes a microporous insulating material. The microporous insulating material includes an aerogel.

[0007] By providing an airtight space including a microporous insulating material around the heating chamber, heat loss due to air circulation between the interior of the heater casing and the outside air can be reduced or avoided. Also, by providing an airtight space including a microporous insulating material around the heating chamber, heat loss due to air convection within the airtight space can be reduced or avoided. Providing an airtight space including a microporous insulating material around the heating chamber can reduce radiative heat transfer. Advantageously, providing an airtight space including a microporous insulating material around the heating chamber can improve insulation of the heating chamber against the outer surface of the heater casing. By providing an airtight space including a microporous insulating material around the heating chamber, a heater assembly for an aerosol generating device can be provided that can reduce heat loss from the heating chamber. By providing an airtight space including a microporous insulating material around the heating chamber, a heater assembly for an aerosol generating device can be provided that can reduce heating of the outer housing of the device that is gripped by a user. By providing an airtight space including a microporous insulating material around the heating chamber, a heater assembly for an aerosol generating device can be provided that can provide effective insulation. Providing an airtight space containing a microporous insulating material may provide improved insulation at the operating temperatures of the aerosol generating device compared to an airtight hollow space.

[0008] The "operating temperature" depends on the type of aerosol-generating device and the aerosol-forming substrate used. The operating temperature of the aerosol-generating device may range from 150 to 300 degrees Celsius. The operating temperature of the aerosol-generating device may range from 200 to 230 degrees Celsius. The operating temperature of the aerosol-generating device may not exceed 280 degrees Celsius.

[0009] The airtight hollow space may contain air as an insulating material. However, the thermal conductivity of air increases with increasing temperature. Microporous insulating materials contain small cavities or pores. Because air or other gaseous compositions are trapped within these cavities, the thermal conductivity of microporous insulating materials is lower with increasing temperature compared to air. Microporous insulating materials can substantially maintain their thermal conductivity at the operating temperature of the aerosol generating device compared to their thermal conductivity at room temperature. The low thermal conductivity of microporous insulating materials provides better insulation. Aerogel has particularly low thermal conductivity, thereby further enhancing its thermal insulation properties. An additional advantage is that aerogel reduces or prevents undesirable odors during heating. In other words, aerogel does not emit unpleasant odors even as temperatures increase.

[0010] Due to better insulation, a heater casing including a microporous insulating material can have a reduced outer diameter. By providing a heater casing with an airtight space including a microporous insulating material, an aerosol generating device can be obtained that can have more compact device dimensions.

[0011] As used herein, the terms "upstream" and "downstream" are used to describe the relative location of components or portions of components of an aerosol-generating device with respect to the direction of airflow through the aerosol-generating device during use. An aerosol-generating device according to the present invention has a proximal end through which aerosol exits the device during use. The proximal end of an aerosol-generating device may also be referred to as the mouth end or downstream end. The mouth end is downstream of the distal end. The distal end of an aerosol-generating article may also be referred to as the upstream end. Components or portions of components of an aerosol-generating device may be described as being upstream or downstream of each other based on their relative location with respect to the airflow path of the aerosol-generating device.

[0012] The proximal end of a heater assembly according to the present invention is configured to be disposed within an aerosol generating device in a direction toward the mouth or downstream end of the device. The distal end of a heater assembly according to the present invention is configured to be disposed within an aerosol generating device in a direction toward the distal or upstream end of the device. The longitudinal axis of the heating chamber may extend between the proximal end of the heating chamber and the distal end of the heating chamber. The longitudinal axis of the heating chamber may extend between the proximal end of the heater assembly and the distal end of the heater assembly.

[0013] The heating chamber may be configured to at least partially receive the aerosol-forming substrate. The heating chamber may comprise a cavity into which the aerosol-forming substrate may be inserted. The aerosol-forming substrate may be part of an aerosol-generating article. The cavity may have a shape corresponding to the shape of the aerosol-generating article to be received therein. The cavity may have a circular cross-section. The cavity may have an elliptical or rectangular cross-section. The cavity may have an inner diameter corresponding to the outer diameter of the aerosol-generating article.

[0014] The heating chamber may comprise an opening at the proximal end of the heating chamber for receiving the aerosol-forming substrate. The opening may also serve as an air outlet. The heating chamber may comprise an air inlet at the distal end of the heating chamber.

[0015] The heating chamber may have an elongated shape. The heating chamber may be a hollow tube. The hollow tube may be formed from a wall of the heating chamber. The wall of the heating chamber may include or be made of a metal or alloy. The wall of the heating chamber may include or be made of stainless steel.

[0016] The heater casing may be positioned radially away from the heating chamber by a distance d. The distance d may be measured perpendicular to the longitudinal axis of the heating chamber. The heating chamber may comprise a heating chamber wall. The heater casing may comprise a heater casing wall. The distance d may be measured radially between the heating chamber wall and the heater casing wall. The distance d may be measured radially between an outer side of the heating chamber wall and an inner side of the heater casing wall.

[0017] The aerogel can be a silicate aerogel. Preferably, the aerogel is of type Chemical Abstracts Service (CAS) number 11296-00-8. Preferably, the aerogel is of type European Commission (EC) number 231-545-4.

[0018] Aerogel is a type of gel from which the liquid has been removed in such a way as to minimize disruption or change in structure when the water is removed.

[0019] The microporous insulating material may comprise a resin, preferably a polymeric resin.

[0020] The polymer resin may provide flexibility to the microporous insulating material so that the layer of microporous insulating material can be wrapped around the heating chamber.

[0021] The microporous insulating material may be composed of aerogel and polymer resin.

[0022] The microporous insulating material may comprise 0.5% to 50% by weight of polymer resin, preferably 0.7% to 40% by weight, more preferably 1% to 30% by weight.

[0023] The microporous insulating material may comprise from 1% to 50% by weight of polymer resin, preferably from 5% to 45% by weight, more preferably from 10% to 40% by weight, even more preferably from 20% to 40% by weight, and most preferably about 30% by weight.

[0024] The microporous insulating material may comprise 1% to 99% by weight of aerogel, preferably 50% to 90% by weight, more preferably 60% to 80% by weight, and most preferably about 70% by weight.

[0025] The airtight space may include a polyimide layer. The polyimide layer may be disposed around the microporous insulating material. The polyimide layer may be disposed in direct contact with the microporous insulating material.

[0026] The polyimide layer can hold the microporous insulating material. The polyimide layer can hold the microporous insulating material against the heating chamber. The microporous insulating material can be sandwiched between the polyimide layer and the heating chamber. The polyimide layer can partially wrap around the periphery of the microporous insulating material. The polyimide layer can completely wrap around the periphery of the microporous insulating material.

[0027] A gap may be provided between the polyimide layer and the heater casing, which may prevent thermal bridging between the polyimide layer and the heater casing.

[0028] The microporous insulating material may be placed in direct contact with the heating chamber.

[0029] The heater assembly may further comprise a heat dissipation element disposed to at least partially surround the heating chamber. The heat dissipation element may be provided as a graphene layer. The graphene layer may be provided as a coating.

[0030] A heat dissipation element may be disposed between the microporous insulating material and the heating chamber.

[0031] The heat dissipation element can be disposed within the airtight space, the heat dissipation element can be disposed as a coating on the periphery of the heating chamber, or the heat dissipation element can be disposed as a coating on the inner surface of the microporous insulating material.

[0032] The heat dissipation element may interact synergistically with the microporous insulating material to improve overall thermal performance. Without being bound by any theory, it is believed that the heat dissipation element may evenly distribute heat around the heating chamber, while the microporous insulating material may prevent this distributed thermal energy from escaping, at least radially outward. Additionally, the heat dissipation element may have properties described below that may further reduce radially outward heat dissipation.

[0033] The heat dissipation element may be made from a material that dissipates heat primarily in one or both of an axial and a tangential direction relative to the longitudinal axis of the heating chamber.

[0034] The heat dissipation element may dissipate less heat radially relative to the longitudinal axis of the heating chamber than axially and tangentially.

[0035] The terms "mainly" and "less" preferably refer to the physical properties of the material of the heat dissipation element, in particular the heat dissipation being higher in at least one of the axial and tangential directions of the heat dissipation element disposed at least partially surrounding the heating chamber than in the radial direction of the heat dissipation element. More preferably, the heat dissipation is two times, preferably three times, more preferably four times, and most preferably five times higher in at least one of the axial and tangential directions compared to the radial direction.

[0036] Heat dissipation may be determined by measuring the temperature difference between one point on the material and a second, distant point: the higher the temperature difference, the higher the heat dissipation in the direction of the measurement point.

[0037] As a result, the heating chamber provides less heat to the housing immediately surrounding the aerosol generating device and more heat to the remainder of the aerosol generating device so that the overall heating is more evenly distributed throughout the aerosol generating device.

[0038] The heat dissipation element may be made of graphene. Graphene has the advantage of being anisotropic with respect to its thermal insulation properties. The thermal insulation is relatively poor in the X and Y directions, while the thermal insulation is high in the Z direction. The graphene may be disposed surrounding the heating chamber, such that the X and Y directions of the graphene correspond to the axial and tangential directions with respect to the longitudinal axis of the heating chamber. As a result, heat is dissipated well in the axial and tangential directions. The Z direction of the graphene corresponds to the radial direction with respect to the longitudinal axis of the heating chamber. As a result, heat is not dissipated well in the radial direction, which prevents the surrounding housing of the aerosol generating device from becoming excessively hot.

[0039] In general, any heat dissipation element made from a material with anisotropic insulating properties, such as those described above for graphene, may be utilized to improve the transport of heat away from the heating chamber in the axial and tangential directions.

[0040] The heat dissipation element may completely surround the heating chamber, in other words, the heat dissipation element may surround the periphery of the heating chamber.

[0041] The heat dissipating element may extend the entire length of the heating chamber. Preferably, the entire outer surface of the heating chamber is covered by the heat dissipating element.

[0042] The heat dissipation element may extend distally across the heating chamber, which has the advantage that the heat is dissipated further into the aerosol generating device, so that the overall heat can be dissipated more evenly to the surrounding environment without creating any hot spots on the aerosol generating device housing that may be uncomfortable for the user to touch.

[0043] As used herein, the term "axial" refers to a direction along or parallel to the longitudinal axis of the heating chamber, which is preferably the same as or parallel to the longitudinal axis of the aerosol-generation device.

[0044] As used herein, the term "tangential" refers to a direction along or parallel to a tangent with respect to the longitudinal axis of the heating chamber.

[0045] As used herein, the term "radial" refers to a direction perpendicular to the axial direction and perpendicular to the tangential direction. This term refers to the direction in which the radius of the heating chamber would be measured by one skilled in the art.

[0046] The heat dissipation element may be formed from one of a rectangular sheet, a T-shaped sheet, and two connected rectangular sheets.

[0047] If the heat dissipation element is formed from a rectangular sheet, the heat dissipation element may surround only the heating chamber. Alternatively, the rectangular sheet may preferably be sized so that the heat dissipation element surrounds not only the heating chamber but also a portion of the region distal to the heating chamber. As described herein, heat may therefore be more uniformly dissipated throughout the aerosol generating device.

[0048] If the heat dissipation element is formed from a T-shaped sheet, the "head" of the sheet may wrap around the heating chamber, while the "stem" of the sheet may extend further distally into the aerosol-generating device. Again, by providing such a heat dissipation element, the heater may be more uniformly dissipated into the aerosol-generating device.

[0049] Finally, the heat dissipation element may be formed from two connected rectangular sheets. In this embodiment, one of the rectangular sheets is preferably disposed surrounding the heating chamber, while the other rectangular sheet is preferably disposed distal to the heating chamber to dissipate heat more uniformly into the aerosol generating device. The connection between the rectangular sheets ensures that heat can be transferred from the sheet wrapped around the heating chamber to the sheet distal to the heating chamber.

[0050] In a preferred embodiment, the heat dissipation element may be provided as a coating.The heat dissipation element may be provided as a coating on one or both of the periphery of the heating chamber and the microporous insulating material.

[0051] The distance d between the heating chamber and the heater casing may be 1.5 mm to 7 mm. The distance d between the heating chamber and the heater casing may be 2 mm to 4 mm, preferably about 3.1 mm.

[0052] The heater casing may be coaxially aligned around the heating chamber. The heating chamber and the heater casing may have matching shapes. The matching shapes may allow for a constant radial distance d to be provided between the heater casing and the heating chamber.

[0053] The heater casing wall may match the shape of the heater chamber wall along the longitudinal axis of the heater chamber such that the distance d may be approximately constant. For example, the heater chamber may be a hollow tube, and the heater casing wall may be a cylindrical wall coaxially aligned around the heater chamber. The distance d may be measured radially between the outer diameter of the heater chamber hollow tube and the inner diameter of the heater casing cylindrical wall. For example, the heater chamber may be a hollow truncated cone, and the heater casing wall may be a conical wall coaxially aligned. Those skilled in the art will understand that other types of matching shapes are possible. For example, the matching shape may be curved or wavy, or may include a combination of different shapes along the longitudinal axis of the heater chamber.

[0054] The heating chamber and heater casing may have deviating shapes. The shape of the heater casing wall may deviate to some extent from the shape of the heating chamber wall along the longitudinal axis of the heating chamber. The shape of the heater casing wall may deviate from the shape of the heating chamber wall along the longitudinal axis of the heating chamber such that the distance d does not vary by more than 1 millimeter along the longitudinal axis of the heating chamber. For example, the heating chamber may be a right-frustoconical hollow cylinder, and the heater casing wall may be a slightly conical hollow cylinder coaxially aligned around the heating chamber. Due to the conical shape of the heater casing wall, the distance d may vary by 1 millimeter or less along the longitudinal axis of the heating chamber.

[0055] The outer diameter of the heater casing may be measured perpendicular to the longitudinal axis of the heating chamber and may be between 8 millimeters and 20 millimeters, preferably between 14 millimeters and 18 millimeters, and preferably about 16 millimeters.

[0056] The outer diameter of the heating chamber may be measured perpendicular to the longitudinal axis of the heating chamber. The ratio of the outer diameter of the heater casing to the outer diameter of the heating chamber may be 1.3 to 3.5, preferably 1.5 to 2.5, and more preferably about 2.0. Specifically, in one embodiment, the outer diameter of the heating chamber may be about 5.6 millimeters and the outer diameter of the heater casing may be about 17 millimeters, resulting in a ratio of about 3.0. In one embodiment, the outer diameter of the heating chamber may be about 5.6 millimeters and the outer diameter of the heater casing may be about 16.5 millimeters, resulting in a ratio of about 2.95. In one embodiment, the outer diameter of the heating chamber may be about 7.6 millimeters and the outer diameter of the heater casing may be about 16.5 millimeters, resulting in a ratio of about 2.17.

[0057] The airtight space is hermetically sealed from the outside air, in other words, the interior of the airtight space is not fluidly connected to the outside air, thereby avoiding heat loss due to gas circulation between the airtight space and the air outside the heater assembly.

[0058] The airtight space may be at ambient pressure. The gas pressure in the airtight space may be between 0.9 bar and 1.1 bar, preferably about 1.0 bar. The airtight space may be filled with a gaseous composition at about ambient pressure at about 20 degrees Celsius. As known to those skilled in the art, temperature-dependent variations in gas pressure in the airtight space may occur. Providing an airtight space at ambient pressure may be less expensive than producing a vacuum airtight space under vacuum. Vacuum-based insulation may be more expensive to produce.

[0059] It has been found that a hermetic hollow space having a distance d of 1.5 to 7 millimeters sufficiently reduces heat loss. When such a distance d is provided, the air or other gaseous composition enclosed within the hermetic space may be considered still air. Still air, or non-moving air, further reduces air convection within the hermetic space. Heat loss due to air convection within the hermetic space can be reduced.

[0060] The thermal conductivity of air increases with increasing temperature. At 25 degrees Celsius, the thermal conductivity of air is approximately 0.0262 W / m·K. At an operating temperature of 280 degrees Celsius, the thermal conductivity of air is already approximately 0.043 W / m·K. Therefore, using air alone as an insulating material in an airtight hollow space requires a relatively large air gap thickness to provide sufficient insulation.

[0061] The microporous insulating material may have a lower thermal conductivity than air at room temperature. At high temperatures, the difference between the thermal conductivity of air and the thermal conductivity of the microporous insulating material may be even greater. The thermal conductivity of the microporous insulating material may not increase as rapidly as that of air. The microporous insulating material may substantially maintain its thermal conductivity even at high temperatures. For example, the microporous insulating material may have a thermal conductivity of 0.018 W / m·K at 20°C. At 200°C, the thermal conductivity is 0.022 W / m·K. At a temperature of 400°C, the thermal conductivity increases to 0.028 W / m·K according to ASTM C177. The thermal conductivity of this exemplary microporous insulating material is approximately the same as that of air at room temperature, even above the maximum operating temperature of the aerosol generating device. Lower thermal conductivity provides better insulation.

[0062] An airtight space including an insulating material with low thermal conductivity can have a smaller thickness while still providing sufficient insulation. An airtight space including a microporous insulating material instead of an airtight hollow space containing only air can have a smaller distance d. A smaller distance d can result in a smaller outer diameter of the aerosol generating device.

[0063] Microporous insulating materials suitable for the present invention may have pore diameters of less than 100 nanometers, preferably less than 70 nanometers, more preferably less than 50 nanometers, more preferably less than 20 nanometers, more preferably less than 2 nanometers.

[0064] The microporous insulating material may be inorganic. The microporous insulating material may be ceramic. The microporous insulating material may include silica (SiO2). The microporous insulating material may include pyrogenic silica. The microporous insulating material may include other components such as opacifiers and fibers. The opacifiers may scatter infrared radiation, thereby reducing its transmission.

[0065] The microporous insulating material of the present disclosure has a porosity of 500 kg / m 3 less than 400 kg / m 3 less than 300 kg / m 3 It may have a nominal density of less than 1000 .mu.m.

[0066] The microporous insulating material of the present invention may have a thermal conductivity of less than 0.05 W / m·K, preferably less than 0.04 W / m·K, more preferably less than 0.03 W / m·K, and more preferably less than 0.02 W / m·K, according to ASTM C177 at 20° C. The microporous insulating material may have a thermal conductivity of less than 0.05 W / m·K, preferably less than 0.04 W / m·K, and more preferably less than 0.03 W / m·K, according to ASTM C177, at 280° C. The thermal conductivity of the microporous insulating material may increase by up to 40 percent, preferably up to 30 percent, and more preferably up to 20 percent, at 280° C. compared to the thermal conductivity of the microporous insulating material at 20° C.

[0067] At the operating temperature of the aerosol generating device, an airtight space containing a microporous insulating material may have a lower thermal conductivity than the same airtight hollow space containing ambient air instead.

[0068] The airtight space may be completely filled with a microporous insulating material.

[0069] Alternatively, the airtight space may not be completely filled with the microporous insulating material. By not completely filling the airtight space with the microporous insulating material, the weight of the aerosol generating device may be reduced. However, the airtight space may be at least partially filled with the microporous insulating material. The airtight space may also be at least partially filled with a gaseous composition. The gaseous composition may be at ambient pressure. The gaseous composition may be air. The gaseous composition may include one or more of nitrogen, argon, carbon dioxide, oxygen, krypton, sulfur hexafluoride, or mixtures thereof, or other suitable gaseous compositions.

[0070] By additionally providing a gaseous composition in the airtight space, the weight of the aerosol generating device can be reduced. By providing a gaseous composition in the airtight space, the manufacturing costs can be reduced.

[0071] The volume of the airtight space filled with the microporous insulating material may be 30, 40, 50, 60, 70, 80, or 90 volume percent. The ratio of the microporous insulating material to the gaseous composition may depend on the operating temperature of the aerosol-generating device. Aerosol-generating devices with higher operating temperatures may require more microporous insulating material.

[0072] The airtight space may include at least one air gap, and the gaseous composition may be provided within the air gap.

[0073] The airtight space may include one air gap. The airtight space may include two air gaps. The airtight space may include three air gaps. The microporous insulating material may be radially sandwiched between the two air gaps.

[0074] The air gap may have a thickness measured perpendicular to the longitudinal axis of the heating chamber, which may be between 0.5 millimeters and 4 millimeters, preferably between 1 millimeter and 3 millimeters, and more preferably about 2 millimeters.

[0075] One or more air gaps may be within the microporous insulating material. The one or more air gaps may extend in a direction parallel to the longitudinal axis of the aerosol generating device. The one or more air gaps may have a longitudinal extension that is the same as or shorter than the longitudinal extension of the microporous insulating material. The one or more air gaps may have a circular cross-section. Alternatively, the one or more air gaps may not extend around the entire circumference of the microporous insulating material. The one or more air gaps may be completely surrounded by the microporous insulating material. The one or more air gaps may be in direct contact with the first and second connecting walls, as described in more detail below. The one or more air gaps may be in direct contact with the heating chamber. The one or more air gaps may be in direct contact with the heater casing.

[0076] By providing an air gap within the airtight space, the weight of the aerosol generating device can be reduced. By providing an air gap within the airtight space, the manufacturing costs can be reduced.

[0077] The microporous insulating material may be in direct contact with the heating chamber. The microporous insulating material may be surrounded by an air gap. The temperature around the heating chamber may decrease radially with increasing distance from the longitudinal axis of the heating chamber. The microporous insulating material may provide better insulation at higher temperatures than air, for example. An assembly in which the microporous insulating material is in direct contact with the heating chamber surrounded by an air gap may have improved insulation over an assembly in which the opposite is true.

[0078] The heater assembly may further include a first connecting wall connecting the heating chamber and the heater casing and a second connecting wall connecting the heating chamber and the heater casing. An airtight space may be defined between the heating chamber, the heater casing, and the first and second connecting walls. The airtight space may be limited by the heating chamber, the heater casing, and the first and second connecting walls. The first and second connecting walls may provide for easy assembly of the airtight space. The first and second connecting walls may provide for simple manufacture of the airtight space. By providing the first and second connecting walls, a defined distance d of the heater casing from the heating chamber may be ensured. By providing the first and second connecting walls, accurate placement of the microporous insulating material may be ensured. The first and second connecting walls may be in contact with the microporous insulating material, thereby preventing heat loss due to air convection over the proximal and distal ends of the microporous insulating material.

[0079] The first and second connecting walls may each extend between a wall of the heating chamber and a wall of the heater casing. The first and second connecting walls may sealingly connect the heater casing to an outer wall of the heating chamber. The connecting walls may be oriented perpendicular to the longitudinal axis of the heating chamber. The first connecting wall may be a proximal connecting wall. The second connecting wall may be a distal connecting wall.

[0080] The microporous insulating material may be in direct contact with the heating chamber. The microporous insulating material may be in direct contact with the heater casing. The microporous insulating material may be in direct contact with the first and second connecting walls. The microporous insulating material may be in direct contact with the heating chamber and the heater casing. The microporous insulating material may be in direct contact with the heating chamber, the heater casing, and the first and second connecting walls. The microporous insulating material may be attached between the first connecting wall and the second connecting wall. The microporous insulating material may be disposed across the distance between the first connecting wall and the second connecting wall. The microporous insulating material may be attached between the first connecting wall and the second connecting wall, while not in contact with one or both of the heater casing and the heating chamber.

[0081] The microporous insulating material may have elongated extensions. The microporous insulating material may extend parallel to the longitudinal axis of the heating chamber. The microporous insulating material may be a hollow tube extending around the heating chamber.

[0082] The microporous insulating material may have a thickness measured perpendicular to the longitudinal axis of the heating chamber. The microporous insulating material may have a thickness equal to the distance d. The thickness of the microporous insulating material may be between 1 mm and 7 mm, preferably between 2 mm and 6 mm, and more preferably between 3 mm and 5 mm.

[0083] The microporous insulating material may be formed from a single element. Alternatively, the microporous insulating material may be formed from at least two insulating elements. The microporous insulating material may be formed from two insulating elements. The microporous insulating material may be formed from at least a first insulating element including at least a first connecting element and a second insulating element including at least a second connecting element. The first and second connecting elements may be configured as mating connecting elements. When connected, the mating connecting elements may enable connection of the first and second microporous insulating elements. The connected first and second connecting elements may result in the overall insulating material forming a hollow tube. The hollow tube may have an inner diameter corresponding to the outer diameter of the heating chamber. Providing the microporous insulating material from two insulating elements may provide for easy assembly of the microporous insulating material around the heating chamber. Forming the microporous insulating material from two insulating elements may provide a perfect form-fit between the microporous insulating material and the heating chamber. Providing a perfect form-fit between the microporous insulating material and the heating chamber may ensure better thermal insulation.

[0084] The first and second connection elements may be configured as male and female connection elements, form-fit connection elements, snap-fit ​​connection elements, bayonet connection elements, or combinations thereof, or other commonly used connection elements known to those skilled in the art. The first connection element may include a male connection element and the second connection element may include a female connection element. The first connection element and the second connection element may include form-fit connection elements. The first connection element and the second connection element may include snap-fit ​​connection elements. The first connection element and the second connection element may include bayonet connection elements.

[0085] The microporous insulating material may be configured as a two-piece assembly. The two-piece assembly may include a first insulating element and a second insulating element. The first insulating element and the second insulating element may be in the form of, for example, a hollow semi-cylindrical element. The hollow semi-cylindrical element may include mating first and second connecting elements. When connected, the hollow semi-cylindrical elements may form a single hollow tube. The inner diameter of the hollow tube may be the same size as the outer diameter of the heating chamber, thereby ensuring easy assembly. On the other hand, a microporous insulating material formed as a single element having an inner diameter the same as the outer diameter of the heating chamber may be more difficult to assemble around the heating chamber due to friction. Close proximity or direct contact between the microporous insulating material and the heating chamber may improve the insulation of the heating chamber.

[0086] The heating chamber may include a temperature sensor. The temperature sensor may be on the top of the heating chamber. The microporous insulating material may have a shape that matches the temperature sensor. The microporous insulating material may have a cavity facing the temperature sensor. The microporous insulating material may be completely enclosed around the heating chamber. The temperature sensor may be surrounded by the microporous insulating material. The temperature sensor may be sandwiched between the heating chamber and the microporous insulating material.

[0087] The heater assembly may further comprise a heating element. The heating chamber may include a heating element.

[0088] The heating element may be disposed at least partially around the heating chamber. The heating element may be disposed at least partially around the wall of the heating chamber. Preferably, the heating element is disposed completely coaxially around the outer periphery of the wall of the heating chamber. The heating element may be disposed along at least a portion of the longitudinal axis of the heating chamber.

[0089] The heating element may comprise one or more conductive tracks on an electrically insulating substrate. The one or more conductive tracks may be resistive heating tracks. The one or more conductive tracks may be configured as an inductively heated susceptor. The electrically insulating substrate may be a flexible substrate.

[0090] The heating element may be flexible and may be wrapped around the heating chamber, or may be disposed between the heating chamber and the heater casing.

[0091] The microporous insulating material may have a longitudinal extension that is the same as or greater than the longitudinal extension of the heating element, thereby ensuring adequate insulation of the heat generated by the heating element.

[0092] The microporous insulating material may extend around the heating element. The microporous insulating material may be in direct contact with the heating element.

[0093] In all aspects of the present disclosure, the heating element may comprise an electrically resistive material. Suitable electrically resistive materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may comprise doped or undoped ceramics.

[0094] As noted, in any of the aspects of the present disclosure, the heating element may be part of the heating chamber of a heater assembly for an aerosol-generating device. The heater assembly may include an internal heating element, an external heating element, or both an internal and an external heating element, where "internal" and "external" refer to the aerosol-forming substrate. The internal heating element may take any suitable form. For example, the internal heating element may take the form of a heating blade. Alternatively, the internal heater may take the form of a casing or substrate having different conductive portions or an electrically resistive metal tube. Alternatively, the internal heating element may be one or more heated needles or rods that pass through the center of the aerosol-forming substrate. Other alternatives include a heated wire or filament, such as Ni-Cr (nickel-chromium), platinum, tungsten, or alloy wire or heating plate. Optionally, the internal heating element may be disposed within or on a rigid carrier material. In one such embodiment, the electrically resistive heating element may be formed using a metal that has a well-defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track on a suitable insulating material, such as a ceramic material, and then sandwiched in another insulating material, such as glass. The heater thus formed may be used to both heat the heating element and monitor its temperature during operation.

[0095] The external heating element may take any suitable form. For example, the external heating element may take the form of one or more flexible heating foils on a dielectric substrate such as polyimide. The flexible heating foils may be shaped to fit the periphery of the substrate-receiving cavity. Alternatively, the external heating element may take the form of a metal grid, a flexible printed circuit board, a molded-in circuit component (MID), a ceramic heater, a flexible carbon fiber heater, or may be formed using a coating technique such as plasma deposition on a suitably shaped substrate. The external heating element may also be formed using a metal that has a well-defined relationship between temperature and resistivity. In such an exemplary device, the metal may be formed as a track between two layers of suitable insulating material. An external heating element formed in this manner may be used both to heat the external heating element and to monitor the temperature of the external heating element during operation.

[0096] The heating element advantageously heats the aerosol-forming substrate by thermal conduction. The heating element may be in at least partial contact with the substrate or at least partial contact with a carrier on which the substrate is deposited. Alternatively, heat from either an internal or external heating element may be conducted to the substrate by a thermally conductive element.

[0097] In operation, the aerosol-forming substrate may be completely contained within the aerosol-generating device, in which case the user may puff on the mouthpiece of the aerosol-generating device. Alternatively, in operation, the smoking article containing the aerosol-forming substrate may be partially contained within the aerosol-generating device, in which case the user may puff on the smoking article directly.

[0098] The heating element may be configured as an induction heating element. The induction heating element may comprise an induction coil and a susceptor. Generally, the susceptor is a material capable of generating heat when penetrated by an alternating magnetic field. According to the present invention, the susceptor may be conductive, magnetic, or both conductive and magnetic. The alternating magnetic field generated by one or several induction coils heats the susceptor, which then transfers heat to the aerosol-forming substrate, thereby forming the aerosol. Heat transfer may be primarily by thermal conduction. Such heat transfer is best when the susceptor is in intimate thermal contact with the aerosol-forming substrate. When an induction heating element is employed, the induction heating element may be configured as an internal heating element as described herein or as an external heater as described herein. When the induction heating element is configured as an internal heating element, the susceptor element is preferably configured as a pin or blade for penetrating the aerosol-generating article. When the induction heating element is configured as an external heating element, the susceptor element is preferably configured as a cylindrical susceptor that at least partially surrounds or forms a sidewall of the cavity.

[0099] The heating chamber may include a central region comprising the heating element. The term central region refers to the longitudinal direction. The heating chamber may further include a proximal region and a distal region. The proximal region and the distal region may be spaced apart from the heating element in the longitudinal direction. During use, the proximal region and the distal region may be cooler than the central region of the heating chamber. The first connecting wall may contact the heating chamber in the proximal region, and the second connecting wall may contact the heating chamber in the distal region. Thus, the first connecting wall and the second connecting wall may contact the heating chamber at the coldest point of the heating chamber during use. This may further reduce heat loss from the heating chamber to the connecting walls and the heater casing. Thermal insulation may be further improved.

[0100] The walls of the heating chamber may be made of stainless steel, which may advantageously enhance the effect that during use the proximal and distal regions may be cooler than the central region of the heating chamber.

[0101] The heater casing wall thickness may be less than about 2 millimeters. The heater casing wall thickness may be less than 1.2 millimeters, preferably about 0.8 millimeters. One or both of the first connecting wall and the second connecting wall may have a thickness less than 1.2 millimeters, preferably about 0.8 millimeters. Having such thin walls may minimize the thermal mass of the heater casing, which may further reduce heat loss from the heating chamber.

[0102] One or more of the heater casing wall and the first and second connecting walls may be made of a low thermal conductivity material. This may further reduce heat loss from the heating chamber. The heater casing wall may include or be made of a plastic material. The first and second connecting walls may include or be made of a plastic material. The plastic material may include one or both of polyaryletherketone (PAEK), polyetheretherketone (PEEK), and polyphenylenesulfone (PPSU). Preferably, the plastic material includes polyphenylenesulfone (PPSU).

[0103] The inside of the heater casing wall may include a metal coating. The inside of one or both of the first connecting wall and the second connecting wall may include a metal coating. The metal coating may reduce the emissivity of the inside of the wall. For example, the emissivity of a PEEK wall may be reduced from about 0.95 to about 0.4. The metal coating may reflect thermal radiation emitted from the heating chamber. The metal coating may provide additional insulation of the heating chamber from the outside of the heater casing. The metal coating may be a low-emissivity metal coating. The metal coating may include one or more of aluminum, gold, and silver.

[0104] The present invention further relates to an aerosol generating device comprising a heater assembly as described herein.

[0105] The aerosol generating device preferably includes a power supply configured to provide power to the heating element. The power supply preferably includes a power source. The power source is preferably a battery, such as a lithium-ion battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging. For example, the power source may have a capacity sufficient to allow continuous generation of aerosol for approximately six minutes, or a multiple of six minutes. In another example, the power source may have a capacity sufficient to allow a predetermined number of puffs, or discontinuous activation of the heater assembly.

[0106] The power supply may comprise control electronics. The control electronics may comprise a microcontroller. The microcontroller is preferably a programmable microcontroller. The electrical circuit may include further electronic components. The electrical circuit may be configured to regulate the supply of power to the heater assembly. Power may be supplied to the heater assembly continuously after activation of the system, or may be supplied intermittently (e.g., between puffs). Power may be supplied to the heater assembly in the form of current pulses.

[0107] The present invention further relates to an aerosol-generating system comprising an aerosol-generating device as described herein and an aerosol-forming substrate configured to be at least partially inserted into a heated chamber. The aerosol-forming substrate may be part of an aerosol-generating article, which may be configured to be at least partially inserted into a heated chamber.

[0108] The term "aerosol-forming substrate" as used herein refers to a substrate capable of releasing a volatile compound capable of forming an aerosol. The volatile compound may be released by heating or burning the aerosol-forming substrate. As an alternative to heating or burning, in some cases the volatile compound may be released by a chemical reaction or by mechanical stimulation such as ultrasound. The aerosol-forming substrate may be solid or liquid, or may contain both solid and liquid components. The aerosol-forming substrate may be part of an aerosol-generating article.

[0109] The aerosol-forming substrate may be a solid aerosol-forming substrate. The aerosol-forming substrate may include both solid and liquid components. The aerosol-forming substrate may include a tobacco-containing material containing volatile tobacco flavor compounds that are released from the substrate upon heating. The aerosol-forming substrate may include a non-tobacco material. The aerosol-forming substrate may include an aerosol former that facilitates the formation of a high-density and stable aerosol. Examples of suitable aerosol formers are glycerin and propylene glycol.

[0110] As used herein, the term "aerosol-generating article" refers to an article that includes an aerosol-forming substrate capable of emitting a volatile compound that can form an aerosol. The aerosol-generating article may be disposable.

[0111] As used herein, the term "aerosol-generating device" refers to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-generating device may interact with one or both of an aerosol-generating article including the aerosol-forming substrate and a cartridge including the aerosol-forming substrate. In some examples, the aerosol-generating device may heat the aerosol-forming substrate to facilitate the release of volatile compounds from the substrate. An electrically operated aerosol-generating device may include an atomizer, such as an electric heater, for heating the aerosol-forming substrate to form an aerosol.

[0112] As used herein, the term "aerosol-generating system" refers to the combination of an aerosol-generating device with an aerosol-forming substrate. When the aerosol-forming substrate forms part of an aerosol-generating article, the aerosol-generating system refers to the combination of an aerosol-generating device with the aerosol-generating article. In an aerosol-generating system, the aerosol-forming substrate and the aerosol-generating device work together to generate an aerosol. [Example]

[0113] The following provides a non-exhaustive list of non-limiting examples, any one or more of the features of these examples may be combined with any one or more of the features described above, for example, with any one or more features of other examples, embodiments, or aspects described herein.

[0114] Example A: 1. A heater assembly for an aerosol generating device, comprising: a heating chamber for heating the aerosol-forming substrate; a heater casing disposed around a heating chamber, the heater casing being radially spaced from the heating chamber, the heater casing including an airtight space, the airtight space including a microporous insulating material. Example B: A heater assembly according to embodiment A, further comprising a first connecting wall connecting the heating chamber and the heater casing, and a second connecting wall connecting the heating chamber and the heater casing, wherein an airtight space is defined between the heating chamber, the heater casing, and the first and second connecting walls. Example C: A heater assembly according to Example B, wherein the connecting wall is oriented perpendicular to the longitudinal axis of the heating chamber. Example D: The heater assembly according to any of Examples A-C, wherein the airtight space is at ambient pressure. Example E: A heater assembly according to any of embodiments A-D, wherein the airtight space is at least partially filled with a microporous insulating material. Example F: The heater assembly according to any of Examples A-E, wherein the hermetic space is at least partially filled with the gaseous composition at ambient pressure. Example G: A heater assembly according to any of embodiments A-F, wherein the airtight space includes at least one air gap. Example H: A heater assembly according to example G, wherein the microporous insulating material is radially sandwiched between two air gaps. Example I: The heater assembly according to any of embodiments A-H, wherein the microporous insulating material is in direct contact with the heating chamber. Example J: A heater assembly according to any of Examples A-I, wherein the microporous insulating material is in direct contact with the heater casing. Example K: A heater assembly according to any of Examples A-J, wherein the microporous insulating material is in direct contact with the first and second connecting walls of Example B. Example L: The heater assembly according to any of Examples A-K, wherein the microporous insulating material is in direct contact with the heating chamber, the heater casing, and the first and second connecting walls of Example B. Example M: A heater assembly according to any of claims A-L, wherein the microporous insulating material is formed from at least one first insulating element including at least one first connecting element, and a second insulating element including at least one second connecting element, the first and second connecting elements being configured as mating connecting elements. Example N: The heater assembly according to embodiment M, wherein the first connecting element comprises a male connecting element and the second connecting element comprises a female connecting element. Example 0: The heater assembly according to embodiment M or N, wherein the first connecting element and the second connecting element comprise form-fit connecting elements. Example P: The heater assembly according to any of embodiments MO, wherein the first connecting element and the second connecting element comprise snap-fit ​​connecting elements. Example Q: The heater assembly according to any of embodiments MP, wherein the first connecting element and the second connecting element comprise bayonet connecting elements. Example R: A heater assembly according to any of embodiments A-Q, wherein the microporous insulating material has elongated extensions. Example S: The heater assembly according to any of embodiments A-R, wherein the microporous insulating material extends parallel to the longitudinal axis of the heating chamber. Example T: The heater assembly according to any of embodiments A-S, wherein the distance between the heating chamber and the heater casing is between 1.5 millimeters and 7 millimeters, preferably between 2 millimeters and 4 millimeters, preferably about 3.1 millimeters. Example U: The heater assembly according to any of Examples A-T, further comprising a heating element. Example V: The heater assembly according to embodiment U, wherein the heating element is disposed at least partially around the heating chamber. Example W: A heater assembly according to example U or V, wherein the microporous insulating material has a longitudinal extension that is the same as or greater than the longitudinal extension of the heating element. Example X: The heater assembly according to any one of embodiments U-W, wherein the heating element is flexible and wrapped around the heating chamber. Example Y: The heater assembly according to any one of embodiments U-X, wherein the heating element is disposed between the heating chamber and the heater casing. Example Z: A heater assembly according to any one of embodiments U-Y, wherein the heating element comprises one or more conductive tracks on an electrically insulating substrate. Example AA: The heater assembly according to any of Examples A to Z, wherein the ratio of the outer diameter of the heater casing to the outer diameter of the heating chamber is between 1.3 and 3.5, preferably between 1.5 and 2.5, and more preferably about 2.0. Example AB: The heater assembly according to any of Examples A-AA, wherein the microporous insulating material has a thermal conductivity of less than 0.05 W / m·K, preferably less than 0.04 W / m·K, and more preferably less than 0.03 W / m·K at a temperature of 280 degrees Celsius. Example AC: A heater assembly according to any of Examples A-AB, wherein the thermal conductivity of the microporous insulating material is increased by up to 40 percent, preferably up to 30 percent, and more preferably up to 20 percent at a temperature of 280 degrees Celsius compared to the thermal conductivity of the microporous insulating material at room temperature. Example AD: The heater assembly according to any of Examples A-AC, wherein the microporous insulating material has a pore diameter of less than 100 nanometers, preferably less than 70 nanometers, more preferably less than 50 nanometers, more preferably less than 20 nanometers, more preferably less than 2 nanometers. Example AE: The heater assembly according to any of Examples A-AD, wherein the heating chamber has an elongated shape, preferably wherein the heating chamber is a hollow tube. Example AF: the heating chamber comprising a central region comprising the heating element of Example U; a proximal region; a distal region; the proximal and distal regions are longitudinally spaced from the heating element; The heater assembly according to any of Examples A-AE, wherein the first connecting wall of Example B contacts the heating chamber in the proximal region and the second connecting wall of Example B contacts the heating chamber in the distal region. Example AG: The heater assembly according to any of Examples A-AF, wherein the inside of the heater casing wall comprises a metal coating, and optionally the heating chamber wall comprises stainless steel. Example AH: A heater assembly according to any of Examples A-AG, wherein the thickness of one or more of the heater casing wall and the first and second connecting walls of claim 2 is less than 2 millimeters, preferably less than 1.2 millimeters, preferably about 0.8 millimeters. Example AI: The heater assembly according to any of Examples A-AH, wherein the heater casing wall and one or more of the first and second connecting walls of Example B comprise a plastic material, preferably polyaryletherketone (PAEK), polyetheretherketone (PEEK), or polyphenylenesulfone (PPSU), more preferably polyphenylenesulfone (PPSU). Example AJ: An aerosol generating device comprising a heater assembly according to any one of Examples A to AI. Example AK: An aerosol-generating system comprising an aerosol-generating device according to Example AJ and an aerosol-forming substrate configured to be at least partially received within a heated chamber.

[0115] Features described with respect to one embodiment may equally apply to other embodiments of the invention.

[0116] The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0117] [Figure 1] FIG. 1 shows one embodiment of a heater assembly for an aerosol generating device. [Figure 2] FIG. 2 shows one embodiment of the heating chamber of the heater assembly. [Figure 3] FIG. 3 shows one embodiment of a heater assembly for an aerosol generating device. [Figure 4] FIG. 4 shows one embodiment of a heater assembly for an aerosol generating device. [Figure 5] FIG. 5 shows one embodiment of a heater assembly for an aerosol generating device. [Figure 6] FIG. 6 shows one embodiment of a heater assembly for an aerosol generating device. [Figure 7] FIG. 7 shows one embodiment of a microporous insulating material for a heater assembly for an aerosol generating device. [Figure 8] FIG. 8 shows one embodiment of an aerosol generating device. [Figure 9] FIG. 9 shows one embodiment of an aerosol generating device. [Figure 10] FIG. 10 shows an embodiment of an aerosol generating device that includes an aerosol insulating material. DETAILED DESCRIPTION OF THE INVENTION

[0118] FIG. 1 schematically illustrates a heater assembly 10. The heater assembly 10 includes a heating chamber 12 for heating an aerosol-forming substrate. The heating chamber 12 has an elongated shape. The heating chamber 12 includes a heating chamber wall 14 that surrounds a cavity for insertion of the aerosol-forming substrate. The heating chamber wall 14 forms a hollow tube. The heater assembly 10 further includes a heater casing. The heater casing is coaxially disposed around the heating chamber 12. The heater casing includes a cylindrical wall of a heater casing 16. The heater casing is further disposed radially spaced a distance d from the heating chamber 12. The distance d is measured radially between the outer diameter of the hollow tube formed by the heating chamber wall 14 and the inner diameter of the cylindrical wall of the heater casing 16. The heating chamber wall 14 and the wall of the heater casing 16 have matching shapes. Thereby, the distance d is constant along the longitudinal axis of the heating chamber 12.

[0119] The heater assembly 10 further comprises a first connecting wall 18 at a proximal end of the heater assembly 10. The heater assembly 10 further comprises a second connecting wall 20 at a distal end of the heater assembly 10. The first and second connecting walls 18, 20 are oriented perpendicular to the longitudinal axis of the heating chamber 12. The heater assembly 10 further comprises an airtight space 22. The airtight space 22 is defined between the heating chamber wall 14, the heater casing wall 16, and the first and second connecting walls 18, 20.

[0120] FIG. 2 shows one embodiment of the heating chamber 12. The heating chamber 12 includes a central region that includes a heating element. The heating element is disposed partially around the heating chamber 12. The walls of the heating chamber 12 are metal tubing, preferably stainless steel tubing. The heating element is flexible and wrapped around the metal tubing. The heating element includes an electrically insulating flexible substrate 26 that includes an electrically conductive heating track 24. In the illustrated embodiment, the proximal and distal edge portions of the flexible substrate 26 are not covered by the heating track 24. In other embodiments, different regions of the flexible substrate 26, or even the entire surface, may be covered by the heating track 24. The proximal and distal regions 28 and 30 of the heating chamber 12 are longitudinally spaced from the heating element.

[0121] Figure 3 shows one embodiment of a heater assembly 10 comprising the heating chamber 12 of Figure 2. A heating element is disposed between the heating chamber 12 and a heater casing.

[0122] The first and second connecting walls 18, 20 sealingly connect the heater casing wall 16 with the heating chamber wall 14, thereby hermetically enclosing the airtight space 22.

[0123] The first and second connecting walls 18, 20 contact the heating chamber 12 at a proximal region 28 and a distal region 30, respectively. The first and second connecting walls 18, 20 contact the heating chamber 12 at a location spaced from the heating element. Therefore, when heated during use, the first and second connecting walls 18, 20 contact the heating chamber 12 at its coldest point. This further reduces heat loss due to heat transfer from the heating chamber 12 to the connecting walls 18, 20 and the heater casing by thermal conduction. Thermal insulation may also be further improved.

[0124] The airtight space 22 includes a microporous insulating material 32. The microporous insulating material 32 may be, for example, MICROSIL microporous insulating material manufactured by ZIRCAR Ceramics, Inc., Excelfrax® manufactured by Unifrax I LLC, Microtherm 1000 grade manufactured by Promat Inc., or other commercially available microporous insulating materials. Particularly preferably, the microporous insulating material 32 comprises, or preferably consists of, silica aerogel and a polymer resin. Particularly preferably, the microporous insulating material 32 comprises up to 30% polymer resin, with the remainder (1% to 99%) of the microporous insulating material 32 being silica aerogel.

[0125] In the embodiment shown in Figure 3, the entire airtight space 22 is filled with a microporous insulating material 32. The microporous insulating material 32 is in contact with the heating chamber wall 14, the heating track 24, the first and second connecting walls 18 and 20, and the heater casing wall 16. Although not shown, the microporous insulating material 32 shown in Figure 3 may also include one or more air gaps extending in a direction parallel to the longitudinal axis of the aerosol generating device. These air gaps may be in direct contact with the heating chamber wall 14, the heater casing wall 16, or the first and second connecting walls 18, 20. These air gaps may have a shorter longitudinal extension than the microporous insulating material 32.

[0126] Figures 4, 5, and 6 show alternative embodiments in which the airtight space 22 is only partially filled with microporous insulating material 32. The main elements are similar to the heater assembly of Figure 3. In the embodiments shown in Figures 4, 5, and 6, the airtight space 22 includes at least one additional air gap 34. In all of these embodiments, the microporous insulating material 32 is in contact with the first connecting wall 18 and the second connecting wall 20. However, the microporous insulating material 32 may alternatively be in contact with only one of the first and second connecting walls 18, 20. Preferably, the microporous insulating material 32 is in contact only with the first (proximal) connecting wall 18. The microporous insulating material 32 may be attached to the first connecting wall 18 and the second connecting wall 20.

[0127] 4 shows a heater assembly in which an air gap 34 extends around the heater chamber 12. A microporous insulating material 32 extends around the air gap 34, radially spaced from the heater chamber 12. The microporous insulating material 32 is in direct contact with the heater casing wall 16.

[0128] 5 shows an alternative embodiment in which the microporous insulation material 32 is in direct contact with the heating chamber 12. An air gap 34 extends around the microporous insulation material 32, radially spaced from the heating chamber 12. The air gap 34 is in direct contact with the heater casing wall 16.

[0129] 6 shows an alternative embodiment in which the airtight space 22 includes two air gaps 34. One air gap 34 extends around and directly connects with the heating chamber 12. The microporous insulating material 32 extends at a radial distance from this air gap 34. An additional air gap 34 then extends around the microporous insulating material 32 at a radial distance from the microporous insulating material 32. The microporous insulating material 32 is radially sandwiched between the two air gaps 34.

[0130] The airtight space 22 shown in Figures 3, 4, 5, and 6 may be filled with the microporous insulating material 32 in different ratios. For example, half of the volume of the airtight space 22 is filled with the microporous insulating material 32. However, other ratios are possible. For example, 20 volume percent, 30 volume percent, 40 volume percent, 50 volume percent, 60 volume percent, 70 volume percent, 80 volume percent, or 90 volume percent of the airtight space 22 is filled with the microporous insulating material 32.

[0131] FIG. 7 illustrates a two-piece assembly of microporous insulating material 32. All of the heater assemblies 10 illustrated in FIGS. 3, 4, 5, and 6 can include the two-piece assembly of FIG. 7. However, the two-piece assembly is particularly suitable for the embodiments of FIGS. 3 and 5. As can be seen in FIG. 7, microporous insulating material 32 is formed from a first insulating element 36 having a first connecting element 40 and a second insulating element 38 having a second connecting element 42. The first connecting element 40 and the second connecting element 42 are configured as mating connecting elements. When the two first insulating element 36 and second insulating element 38 are connected, the first connecting element 40 and the second connecting element 42 are interconnected. The connection of the first connecting element 40 and the second connecting element 42 provides direct contact between the first insulating element 36 and the second insulating element 38. The first insulating element 36 and the second insulating element 38 can have a hollow semi-cylindrical design, as shown in FIG. 7. However, other shapes and configurations are possible. When connected, the hollow semi-cylinder design provides a hollow tube. The hollow tube can have an inner diameter the same as the outer diameter of the heating chamber 12. The hollow tube may also have an inner diameter the same as the outer diameter of the heating chamber 12 and the heating track 24 combined. This two-piece assembly allows the microporous insulation material 32 to have a perfect fit around the heating chamber 12 and the heating track 24. Furthermore, if the heating chamber includes a temperature sensor (not shown), the inner shape of the microporous insulation material 32 can be configured to fit over the temperature sensor. The microporous insulation material 32 may include a cavity facing the sensor. The cavity may have the same volume and inverse shape as the temperature sensor. The microporous insulation material 32 may be completely closed around the heating chamber 12 and the heating track 24. Using a hollow tube containing only a single element of the microporous insulation material 32 may not provide such a perfect fit with the heating chamber 12.

[0132] Figure 8 shows an embodiment of an aerosol generating device including the heater assembly 10 of Figure 3. The aerosol generating device further includes a power supply. The power supply includes a power source 44 and control electronics 46. The power source 44 may be a rechargeable battery. In the embodiment of Figure 8, the heater casing wall 16 forms part of the outer housing 48 of the aerosol generating device.

[0133] At the opening 50, the aerosol-forming substrate may be at least partially inserted into the heated chamber 12. The aerosol-forming substrate may be part of an aerosol-generating article.

[0134] Figure 9 shows an embodiment of an aerosol generating device that includes the heater assembly 10 of Figure 3. Unlike the embodiment of Figure 8, in the embodiment of Figure 9, the heater assembly 10 is disposed within a separate outer housing 48 of the aerosol generating device.

[0135] FIG. 10 illustrates one embodiment of an aerosol generating device including a heater assembly 10 positioned adjacent to the proximal end of the aerosol generating device. The flexible substrate 26 and heating track 24 of the heating assembly 10 are positioned around the heating chamber 12. A microporous insulating material 32 is positioned around and in contact with the flexible substrate 26 and heating track 24. The microporous insulating material 32 comprises 1% to 99% aerogel and up to 30% polymer resin. The polymer resin is provided so that the microporous insulating material 32 can be wrapped around the flexible substrate 26 with the heating track 24, thereby providing the microporous insulating material 32 as a flexible layer. To hold the microporous insulating material 32 in place, a polyimide layer 52 is positioned surrounding the microporous insulating material 32. The polyimide layer 52a is a flexible layer. The polyimide layer 52 may partially cover the microporous insulating material 32, as shown in FIG. 10. 10 , a proximal overlap is provided between the polyimide layer 52 and the microporous insulating material 32. In other words, the microporous insulating material 32 extends proximally beyond the polyimide layer 52. Similarly, a distal overlap is provided between the polyimide layer 52 and the microporous insulating material 32 such that the microporous insulating material 32 extends distally beyond the polyimide layer 52. Alternatively, the polyimide layer 52 may completely cover the microporous insulating material 32.

[0136] An air gap 54 is provided surrounding the polyimide layer 52. The polyimide layer 52 and the air gap 54 are provided within the airtight space 22. The wall of the heater casing 16 is provided radially outward of the air gap 54.

[0137] The microporous insulating material 32 is in direct contact with the first connecting wall 18 proximal to the microporous insulating material 32. The microporous insulating material 32 is spaced apart from the second connecting wall 20 distal to the microporous insulating material 32. Alternatively, the microporous insulating material 32 may also be spaced apart from the first connecting wall 18. As a further alternative, the microporous insulating material 32 may be in direct contact with both the first connecting wall 18 as well as the second connecting wall 20.

[0138] 10, the heater casing, and more specifically the walls of the heater casing 16, are attached to an inner frame 56 within the aerosol generating device housing 48. The inner frame 56 may hold additional components of the aerosol generating device, such as the heating chamber 12.

Claims

1. 1. A heater assembly for an aerosol generating device, comprising: a heating chamber for heating the aerosol-forming substrate; a heater casing disposed around the heating chamber, the heater casing being radially spaced from the heating chamber, the heater casing including an airtight space, the airtight space including a microporous insulating material, the microporous insulating material including an aerogel.

2. The heater assembly of claim 1 , wherein the aerogel is a silicate aerogel.

3. 3. The heater assembly of claim 1, wherein the microporous insulating material comprises a polymer resin.

4. 4. The heater assembly of claim 3, wherein said microporous insulating material comprises 0.5% to 50% by weight of said polymer resin, preferably 0.7% to 40% by weight, more preferably 1% to 30% by weight.

5. 5. The heater assembly of claim 3 or 4, wherein the microporous insulating material comprises from 1% to 50% by weight of the polymer resin, preferably from 5% to 45% by weight, more preferably from 10% to 40% by weight, even more preferably from 20% to 40% by weight, and most preferably about 30% by weight.

6. 6. The heater assembly of any of claims 1 to 5, wherein the microporous insulating material comprises from 1% to 99% by weight of the aerogel, preferably from 50% to 90% by weight, more preferably from 60% to 80% by weight, and most preferably about 70% by weight.

7. The heater assembly of any preceding claim, wherein the microporous insulating material is flexible.

8. The heater assembly according to any one of claims 1 to 7, wherein the airtight space comprises a polyimide layer.

9. 9. The heater assembly of claim 8, wherein the polyimide layer is disposed around the microporous insulating material, preferably in direct contact with the microporous insulating material.

10. The heater assembly of claim 9 , wherein a gap is provided between the polyimide layer and the heater casing.

11. The heater assembly of any preceding claim, wherein the microporous insulating material is disposed in direct contact with the heating chamber.

12. 12. The heater assembly of any preceding claim, wherein the heater assembly further comprises a heat dissipation element arranged to at least partially surround the heating chamber, preferably wherein the heat dissipation element is provided as a graphene layer, more preferably wherein the graphene layer is provided as a coating.

13. The heater assembly of claim 12 , wherein the heat dissipation element is disposed between the microporous insulating material and the heating chamber and on the periphery of the heating chamber.

14. An aerosol generating device comprising the heater assembly according to any one of claims 1 to 13.

15. 15. An aerosol generation system comprising the aerosol generating device of claim 14 and an aerosol-forming substrate configured to be at least partially received in the heated chamber.

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