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) comprises a heating chamber (12) for heating an aerosol-forming substrate. The heater assembly (10) also includes a heater housing (16). A heater housing (16) is arranged around the heating chamber (12). The heater housing (16) is also arranged radially spaced from the heating chamber (12). The heater housing (16) further comprises an airtight space. The gas-tight space comprises a microporous insulating material (32). The microporous insulating material (32) comprises an aerogel. The invention also relates to an aerosol-generating device comprising a heater assembly (10) and to an aerosol-generating system comprising 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 Art

[0002] There are known aerosol generating devices for generating an inhalable vapor. Such devices can heat an aerosol forming substrate contained in an aerosol generating article without burning the aerosol forming substrate. The aerosol generating article may have a strip shape for insertion into a heating chamber of the aerosol generating device. A heating element is typically disposed in or around the heating chamber for heating 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 can inadvertently dissipate from the heating chamber. The heat can dissipate to the environment or other components of the aerosol generating system. The heat can inadvertently dissipate from the heating chamber via free air convection. The heat can inadvertently dissipate from the heating chamber via radiation. The heat can inadvertently dissipate from the heating chamber via thermal conduction through components of the aerosol generating device. The heat can inadvertently dissipate from the heating chamber via components of the aerosol generating article (e.g., via the aerosol forming substrate) through thermal conduction. The dissipation of heat from the heating chamber can cause heating of components of the device that are not intended to be heated. For example, the housing of the device to be grasped by the user may become uncomfortably hot. The dissipation of heat from the heating chamber can cause heat loss within the heating chamber. Heat loss within the heating chamber can result in less efficient heating. Excessive energy may be required to heat the heating chamber to a desired temperature. Summary of the Invention

[0004] There is a desire for an aerosol generating device that can reduce heat loss from the heating chamber. There is a desire to thermally insulate the heating chamber relative to other components of the aerosol generating device. There is a desire for an aerosol generating device that can reduce the temperature rise of the outer housing of the device to be grasped by the user. There is a desire for an aerosol generating device that can provide effective thermal insulation. There is a desire for an aerosol generating device that can provide thermal insulation at a low manufacturing cost. There is a desire for an aerosol generating device that can provide lightweight thermal insulation. There is a desire for an aerosol generating device that can have improved thermal insulation. There is a desire for an aerosol generating device that can have a heater shell with a reduced outer diameter. There is a desire for an aerosol generating device that can have a more compact device size.

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

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

[0007] Providing an airtight space including a microporous insulating material around the heating chamber can reduce or avoid heat loss due to air circulation between the inside and outside air of the heater housing. Providing an airtight space including a microporous insulating material around the heating chamber can also reduce or avoid heat loss due to air convection within the airtight space. Providing an airtight space including a microporous insulating material around the heating chamber can reduce radiative heat transfer. Advantageously, by providing an airtight space including a microporous insulating material around the heating chamber, the thermal insulation of the heating chamber relative to the outer surface of the heater housing can be improved. By providing an airtight space including a microporous insulating material around the heating chamber, a heater assembly for an aerosol generating device is provided, which 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 is provided, which can reduce the temperature rise of the outer housing of the device to be grasped by the user. By providing an airtight space including a microporous insulating material around the heating chamber, a heater assembly for an aerosol generating device is provided, which can provide effective thermal insulation. By providing an airtight space including a microporous insulating material, improved thermal insulation at the operating temperature of the aerosol generating device can be provided 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 be between 150 and 300 degrees Celsius. The operating temperature of the aerosol generating device may be between 200 and 230 degrees Celsius. The operating temperature of the aerosol generating device may not exceed 280 degrees Celsius.

[0009] The hermetic hollow space may include air as an insulating material. However, at higher temperatures, the thermal conductivity of air increases. The micro-porous insulating material includes small cavities or pores. Air or other gaseous compositions are encapsulated within these cavities, and thus have a lower thermal conductivity than air at elevated temperatures. Compared to the thermal conductivity at room temperature, the micro-porous insulating material can maintain its thermal conductivity almost at the operating temperature of the aerosol generating device. The low thermal conductivity of the micro-porous insulating material results in better thermal insulation. Aerogel has a particularly low thermal conductivity, thereby further improving thermal insulation. Another advantage is that the aerogel reduces or prevents unpleasant odors during the heating process. In other words, the aerogel does not emit unpleasant odors as the temperature increases.

[0010] Due to the better thermal insulation, the heater housing including the micro-porous insulating material can have a reduced outer diameter. Providing a hermetic space including the micro-porous insulating material for the heater housing can result in an aerosol generating device that can have a more compact device size.

[0011] As used herein, the terms "upstream" and "downstream" are used to describe the relative positions of components of an aerosol generating device or portions of components relative to the direction in which air flow passes through the aerosol generating device during use of the aerosol generating device. The aerosol generating device according to the present invention includes a proximal end, through which aerosol exits the device during use. The proximal end of the aerosol generating device may also be referred to as the mouth end or the downstream end. The mouth end is downstream of the distal end. The distal end of the aerosol generating article may also be referred to as the upstream end. Components of the aerosol generating device or portions of components may be described as being upstream or downstream of one another based on their relative positions with respect to the air flow path of the aerosol generating device.

[0012] The proximal end of the heater assembly according to the present invention is configured to be disposed within the aerosol generating device in a direction towards the mouth end or the downstream end of the device. The distal end of the heater assembly according to the present invention is configured to be disposed within the aerosol generating device in a direction towards the distal end or the 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 an aerosol-forming substrate. The heating chamber may include 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 in the cavity. The cavity may have a circular cross-section. The cavity may have an oval 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 include an opening at a proximal end of the heating chamber for receiving an aerosol-forming substrate. The opening may also serve as an air outlet. The heating chamber may include an air inlet at a 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 by the 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 housing may be arranged to be radially spaced apart from the heating chamber by a distance d. The distance d may be measured in a direction orthogonal to the longitudinal axis of the heating chamber. The heating chamber may include the wall of the heating chamber. The heater housing may include the wall of the heater housing. The distance d may be measured radially between the wall of the heating chamber and the wall of the heater housing. The distance d may be measured radially between the outer side of the wall of the heating chamber and the inner side of the wall of the heater housing.

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

[0018] An aerogel is a type of gel from which liquid has been removed in such a way that collapse or change in the structure is minimized upon removal of water.

[0019] The micro-porous insulating material may comprise a resin, preferably a polymer resin.

[0020] The polymer resin may provide flexibility to the micro-porous insulating material such that the micro-porous insulating material layer can be wrapped around the heating chamber.

[0021] The micro-porous insulating material may consist of an aerogel and a polymer resin.

[0022] The micro-porous insulating material may comprise between 0.5 wt% and 50 wt%, preferably between 0.7 wt% and 40 wt%, more preferably between 1 wt% and 30 wt% of the polymer resin.

[0023] The micro-porous insulating material may comprise between 1 wt% and 50 wt%, preferably between 5 wt% and 45 wt%, more preferably between 10 wt% and 40 wt%, more preferably between 20 wt% and 40 wt%, most preferably approximately 30 wt% of the polymer resin.

[0024] The micro-porous insulating material may comprise between 1 wt% and 99 wt%, preferably between 50 wt% and 90 wt%, more preferably between 60 wt% and 80 wt%, most preferably approximately 70 wt% of the aerogel.

[0025] The hermetic space may include a polyimide layer. The polyimide layer may be disposed around the microporous insulating material.

[0026] The polyimide layer may be arranged in direct contact with the microporous insulating material.

[0027] The polyimide layer may hold the microporous insulating material. The polyimide layer may hold the microporous insulating material against the heating chamber. The microporous insulating material may be sandwiched between the polyimide layer and the heating chamber. The polyimide layer may partially cover the periphery of the microporous insulating material. The polyimide layer may completely cover the periphery of the microporous insulating material.

[0028] A gap may be provided between the polyimide layer and the heater housing. This gap may prevent the formation of a thermal bridge between the polyimide layer and the heater housing.

[0029] The microporous insulating material may be arranged in direct contact with the heating chamber.

[0030] The heater assembly may further include a heat dissipation element arranged 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.

[0031] The heat dissipation element may be arranged between the microporous insulating material and the heating chamber.

[0032] The heat dissipation element may be arranged within the hermetic space. The heat dissipation element may be arranged as a coating on the periphery of the heating chamber. Alternatively, the heat dissipation element may be arranged as a coating on the inner surface of the microporous insulating material.

[0033] The heat dissipation element may interact synergistically with the microporous insulating material to improve the overall thermal performance. Without being bound by any theory, we believe that the heat dissipation element may evenly distribute heat around the periphery of the heating chamber, while the microporous insulating material may prevent the escape of this distributed thermal energy at least in the radially outward direction. Additionally, the heat dissipation element may have the properties described below, which may further reduce heat dissipation in the radially outward direction.

[0034] The heat dissipation element may be made of a material that dissipates heat mainly in one or both of the axial direction and the tangential direction relative to the longitudinal axis of the heating chamber.

[0035] The heat dissipation element may dissipate less heat in the radial direction relative to the longitudinal axis of the heating chamber than in the axial direction and the tangential direction.

[0036] The terms "major" and "less" preferably refer to the physical properties of the material of the heat dissipation element, particularly to the heat dissipation in at least one of the axial and tangential directions of the heat dissipation element arranged to at least partially surround the heating chamber being higher than the heat dissipation in the radial direction of the heat dissipation element. More preferably, the heat dissipation in at least one of the axial and tangential directions is 2 times higher, preferably 3 times higher, more preferably 4 times higher, and most preferably 5 times higher compared to the radial direction.

[0037] The heat dissipation can be determined by measuring the temperature difference between a point on the material and a second point at a distance. The higher the temperature difference, the higher the heat dissipation in the direction of the measurement point.

[0038] Therefore, less heat directly enters the housing surrounding the aerosol generating device from the heating chamber, but more heat enters the rest of the aerosol generating device, such that the overall heat is more evenly distributed throughout the aerosol generating device.

[0039] The heat dissipation element can be made of graphene. The advantage of graphene is that it has anisotropic properties regarding its heat insulation characteristics. The heat insulation is relatively poor in the X and Y directions, but is higher in the Z direction. Graphene can be arranged to surround the heating chamber such that the X and Y directions of graphene correspond to the axial and tangential directions relative to the longitudinal axis of the heating chamber. Therefore, heat is dissipated well in the axial and tangential directions. The Z direction of graphene corresponds to the radial direction relative to the longitudinal axis of the heating chamber. Therefore, heat is poorly dissipated in the radial direction, such that the housing surrounding the aerosol generating device does not become too hot.

[0040] Generally, any heat dissipation element made of a material having anisotropic heat insulation characteristics as described above regarding graphene can be used to improve the conveyance of heat away from the heating chamber in the axial and tangential directions.

[0041] The heat dissipation element can completely surround the heating chamber. In other words, the heat dissipation element can surround the outer periphery of the heating chamber.

[0042] The heat dissipation element can extend along the entire length of the heating chamber. Preferably, the entire outer surface of the heating chamber is covered by the heat dissipation element.

[0043] The heat dissipation element can extend in the distal direction over the heating chamber. This has the advantage that heat is further dissipated into the aerosol generating device such that the overall heat can be more evenly dissipated into the surrounding environment without creating any hot spots on the housing of the aerosol generating device that may be uncomfortable for the user to touch.

[0044] As used herein, the term "axial" refers to the direction along or parallel to the longitudinal axis of the heating chamber. The longitudinal axis of the heating chamber is preferably the same as or parallel to the longitudinal axis of the aerosol generating device.

[0045] As used herein, the term "tangential" refers to a direction along or parallel to a tangent relative to the longitudinal axis of the heating chamber.

[0046] 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 a person skilled in the art would measure the radius of the heating chamber.

[0047] The heat dissipation element can be formed by one of a rectangular sheet, a T-shaped sheet, and two connected rectangular sheets.

[0048] If the heat dissipation element is formed by a rectangular sheet, the heat dissipation element can only wrap around the heating chamber. Alternatively, the rectangular sheet can preferably be sized such that the heat dissipation element wraps around the heating chamber and a part of the area away from the heating chamber. As described herein, heat can thus be dissipated more evenly throughout the aerosol generating device.

[0049] In the case where the heat dissipation element is formed by a T-shaped sheet, the "head" of the sheet can wrap around the heating chamber, while the "stem" of the sheet can further extend in the distal direction into the aerosol generating device. Again, by providing such a heat dissipation element, heat can be dissipated more evenly into the aerosol generating device.

[0050] Finally, the heat dissipation element can be formed by two connected rectangular sheets. In this embodiment, one of the rectangular sheets is preferably arranged to wrap around the heating chamber, while the other rectangular sheet is preferably arranged distally of the heating chamber to dissipate heat more evenly into the aerosol generating device. The connection between the rectangular sheets ensures that heat can be transferred from the sheet wrapping around the heating chamber to the sheet distally of the heating chamber.

[0051] As a preferred embodiment, the heat dissipation element can be provided as a coating. The heat dissipation element can be provided as a coating on one or both of the periphery of the heating chamber and the microporous insulating material.

[0052] The distance d between the heating chamber and the heater housing can be between 1.5 mm and 7 mm. The distance d between the heating chamber and the heater housing can be between 2 mm and 4 mm, preferably about 3.1 mm.

[0053] The heater housing can be coaxially aligned around the heating chamber. The heating chamber and the heater housing can have a matching shape. The matching shape can allow for a constant radial distance d to be provided between the heater housing and the heating chamber.

[0054] The wall of the heater housing may match the shape of the wall of the heating chamber along the longitudinal axis of the heating chamber such that the distance d may be substantially constant. For example, the heating chamber may be a hollow tube and the wall of the heater housing may be a cylindrical wall coaxially aligned around the heating chamber. The distance d may be measured in the radial direction between the outer diameter of the hollow tube of the heating chamber and the inner diameter of the cylindrical wall of the heater housing. For example, the heating chamber may be a hollow frustum cone and the wall of the heater housing may be a coaxially aligned conical wall. Those skilled in the art will understand that other types of matching shapes will be 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 heating chamber.

[0055] The heating chamber and the heater housing may have a deviating shape. The shape of the wall of the heater housing may deviate from the shape of the wall of the heating chamber to some extent along the longitudinal axis of the heating chamber. The shape of the wall of the heater housing may deviate from the shape of the wall of the heating chamber along the longitudinal axis of the heating chamber such that the distance d varies by no more than 1 mm along the longitudinal axis of the heating chamber. For example, the heating chamber may be a hollow straight cylinder and the wall of the heater housing may be a slightly conical hollow cylinder coaxially aligned around the heating chamber. Due to the conical shape of the wall of the heater housing, the distance d may vary by no more than 1 mm along the longitudinal axis of the heating chamber.

[0056] The outer diameter of the heater housing may be measured in a direction orthogonal to the longitudinal axis of the heating chamber. The outer diameter of the heater housing may be between 8 mm and 20 mm, preferably between 14 mm and 18 mm, and preferably about 16 mm.

[0057] The outer diameter of the heating chamber may be measured in a direction orthogonal to the longitudinal axis of the heating chamber. The ratio of the outer diameter of the heater housing to the outer diameter of the heating chamber may be between 1.3 and 3.5, preferably between 1.5 and 2.5, more preferably about 2.0. In particular, in one embodiment, the outer diameter of the heating chamber may be about 5.6 mm and the outer diameter of the heater housing may be about 17 mm, resulting in a ratio of about 3.0. In one embodiment, the outer diameter of the heating chamber may be about 5.6 mm and the outer diameter of the heater housing may be about 16.5 mm, resulting in a ratio of about 2.95. In one embodiment, the outer diameter of the heating chamber may be about 7.6 mm and the outer diameter of the heater housing may be about 16.5 mm, resulting in a ratio of about 2.17.

[0058] The hermetic space is hermetically sealed from the outside air. In other words, the interior of the hermetic space is not in fluid connection with the outside air. Thereby, heat loss due to gas circulation between the hermetic space and the air outside the heater assembly can be avoided.

[0059] The hermetic space can be at ambient pressure. The air pressure within the hermetic space can be between 0.9 bar and 1.1 bar, preferably about 1.0 bar. The hermetic space can be filled with a gaseous composition at about ambient pressure at about 20 degrees Celsius. As is known to those skilled in the art, a temperature-dependent change in the air pressure within the hermetic space may occur. Providing the hermetic space at ambient pressure may be less costly to manufacture than providing a evacuated hermetic space under vacuum. The manufacturing cost of vacuum-based thermal insulation may be higher.

[0060] It has been found that a hermetic hollow space with a distance d between 1.5 mm and 7 mm sufficiently reduces heat loss. When this distance d is provided, the air or other gaseous composition enclosed within the hermetic space can be regarded as still air. The still air or non-moving air additionally reduces air convection within the hermetic space. Heat loss due to air convection within the hermetic space can be reduced.

[0061] The thermal conductivity of air increases with increasing temperature. The thermal conductivity of air at 25 degrees Celsius is about 0.0262 W / m·K. At an operating temperature of 280 degrees Celsius, the thermal conductivity of air is already about 0.043 W / m·K. Therefore, using only air as an insulating material within the hermetic hollow space would require a relatively large thickness of air gap to provide sufficient thermal insulation.

[0062] The microporous insulating material can have a lower thermal conductivity than air at room temperature. At higher temperatures, the difference in thermal conductivity between air and 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 can almost maintain its thermal conductivity even at high temperatures. For example, the microporous insulating material can have a thermal conductivity of 0.018 W / m·K at 20 degrees Celsius. At 200 degrees Celsius, the thermal conductivity is 0.022 W / m·K. According to ASTM C177, at a temperature of 400 degrees Celsius, the thermal conductivity increases to 0.028 W / m·K. The thermal conductivity of this exemplary microporous insulating material is almost the same as that of air at room temperature even at temperatures higher than the maximum operating temperature of the aerosol generating device. A lower thermal conductivity results in better thermal insulation.

[0063] The hermetic space including an insulating material with a lower thermal conductivity can have a smaller thickness while still providing sufficient thermal insulation. The hermetic space including the microporous insulating material rather than the hermetic hollow space including only air can have a smaller distance d. The smaller distance d can result in a smaller outer diameter of the aerosol generating device.

[0064] Suitable microporous insulating materials for use in the present invention can have a pore diameter of less than 100 nm, preferably less than 70 nm, more preferably less than 50 nm, more preferably less than 20 nm, more preferably less than 2 nm.

[0065] The microporous insulating material can be inorganic. The microporous insulating material can be ceramic. The microporous insulating material can include silicon dioxide (SiO2). The microporous insulating material can include pyrogenic silica. The microporous insulating material can include other components such as a light-shielding agent and fibers. The light-shielding agent can scatter infrared radiation and thereby reduce the transmission of infrared radiation.

[0066] The microporous insulating material of the present disclosure can have a nominal density of less than 500 kg / m 3 , preferably less than 400 kg / m 3 , more preferably less than 300 kg / m 3 .

[0067] The microporous insulating material of the present invention can 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, even more preferably less than 0.02 W / m K at 20 degrees Celsius and according to ASTM C177. The microporous insulating material can 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 at a temperature of 280 degrees Celsius and according to ASTM C177. The thermal conductivity of the microporous insulating material at a temperature of 280 degrees Celsius can be increased by at most 40%, preferably at most 30%, more preferably at most 20% compared to the thermal conductivity of the microporous insulating material at 20 degrees Celsius.

[0068] At the operating temperature of the aerosol generating device, the hermetic space including the microporous insulating material can have a lower thermal conductivity than the same hermetic hollow space including ambient air as a substitute.

[0069] The hermetic space can be completely filled with the microporous insulating material.

[0070] Alternatively, the hermetic space can be not completely filled with the microporous insulating material. By not completely filling the hermetic space with the microporous insulating material, the weight of the aerosol generating device can be reduced. However, the hermetic space can be at least partially filled with the microporous insulating material. The hermetic space can also be at least partially filled with a gaseous composition. The gaseous composition can be at ambient pressure. The gaseous composition can be air. The gaseous composition can include one or more of nitrogen, argon, carbon dioxide, oxygen, krypton, sulfur hexafluoride or a mixture thereof or other suitable gaseous compositions.

[0071] By additionally providing a gaseous composition to the hermetic space, the weight of the aerosol generating device can be reduced. Providing a gaseous composition to the hermetic space can reduce the manufacturing cost.

[0072] The volume filled with the microporous insulating material in the hermetic space can be 30% by volume, 40% by volume, 50% by volume, 60% by volume, 70% by volume, 80% by volume, or 90% by volume. The ratio of the microporous insulating material to the gaseous composition can depend on the operating temperature of the aerosol generating device. An aerosol generating device with a higher operating temperature may require more microporous insulating material.

[0073] The hermetic space can include at least one air gap. The gaseous composition can be disposed in the air gap.

[0074] The hermetic space can include one air gap. The hermetic space can include two air gaps. The hermetic space can include three air gaps. The microporous insulating material can be sandwiched between two air gaps in the radial direction.

[0075] The air gap can have a thickness measured in a direction orthogonal to the longitudinal axis of the heating chamber. The thickness of the air gap can be between 0.5 mm and 4 mm, preferably between 1 mm and 3 mm, and more preferably about 2 mm.

[0076] One or more air gaps can be within the microporous insulating material. One or more air gaps can extend in a direction parallel to the longitudinal axis of the aerosol generating device. One or more air gaps can have a longitudinal extension that is the same as or shorter than the longitudinal extension of the microporous insulating material. One or more air gaps can have a circular cross-section. Alternatively, one or more air gaps can not extend around the entire perimeter of the microporous insulating material. One or more air gaps can be completely surrounded by the microporous insulating material. As described in more detail below, one or more air gaps can be in direct contact with the first connecting wall and the second connecting wall. One or more air gaps can be in direct contact with the heating chamber. One or more air gaps can be in direct contact with the heater housing.

[0077] Providing an air gap within the hermetic space can reduce the weight of the aerosol generating device. By providing an air gap within the hermetic space, the manufacturing cost can be reduced.

[0078] The microporous insulating material can be in direct contact with the heating chamber. The microporous insulating material can be surrounded by an air gap. The temperature around the heating chamber can decrease radially as the distance from the longitudinal axis of the heating chamber increases. The microporous insulating material can provide better thermal insulation at a higher temperature than, for example, air. The assembly in which the microporous insulating material is in direct contact with the heating chamber and is surrounded by an air gap can have improved thermal insulation compared to the assembly arranged the other way around.

[0079] The heater assembly may further include a first connecting wall connecting the heating chamber and the heater housing and a second connecting wall connecting the heating chamber and the heater housing. An airtight space may be defined between the heating chamber, the heater housing, and the first and second connecting walls. The airtight space may be bounded by the walls of the heating chamber and the heater housing 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. Providing the first and second connecting walls may ensure a defined distance d of the heater housing from the heating chamber. By providing the first and second connecting walls, correct placement of the micro-porous insulation material may be ensured. The first and second connecting walls may be in contact with the micro-porous insulation material, thereby preventing heat loss via air convection at the proximal and distal ends of the micro-porous insulation material.

[0080] Each of the first and second connecting walls may extend between the wall of the heating chamber and the wall of the heater housing. The first and second connecting walls may sealingly connect the heater housing to the 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.

[0081] The micro-porous insulation material may be in direct contact with the heating chamber. The micro-porous insulation material may be in direct contact with the heater housing. The micro-porous insulation material may be in direct contact with the first and second connecting walls. The micro-porous insulation material may be in direct contact with the heating chamber and the heater housing. The micro-porous insulation material may be in direct contact with the heating chamber, the heater housing, and the first and second connecting walls. The micro-porous insulation material may be installed between the first and second connecting walls. The micro-porous insulation material may be arranged to span the distance between the first and second connecting walls. The micro-porous insulation material may be installed between the first and second connecting walls without contacting one or both of the heater housing and the heating chamber.

[0082] The micro-porous insulation material may have an elongated extension. The micro-porous insulation material may extend parallel to the longitudinal axis of the heating chamber. The micro-porous insulation material may be a hollow tube extending around the heating chamber.

[0083] The micro-porous insulation material may have a thickness measured in a direction orthogonal to the longitudinal axis of the heating chamber. The micro-porous insulation material may have the same thickness as the distance d. The thickness of the micro-porous insulation material may be between 1 millimeter and 7 millimeters, preferably between 2 millimeters and 6 millimeters, more preferably between 3 millimeters and 5 millimeters.

[0084] The micro-porous insulating material can be formed by a single element. Alternatively, the micro-porous insulating material can be formed by at least two insulating elements. The micro-porous insulating material can be formed by two insulating elements. The micro-porous insulating material can be formed by 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 connecting element and the second connecting element can be configured as mating connecting elements. When connected, the mating connecting elements can effect the connection of the first micro-porous insulating element and the second micro-porous insulating element. The connected first connecting element and second connecting element can cause the overall insulating material to form a hollow tube. The hollow tube can have an inner diameter corresponding to the outer diameter of the heating chamber. Providing the micro-porous insulating material from two insulating elements can provide for easy assembly of the micro-porous insulating material around the heating chamber. By forming the micro-porous insulating material from two insulating elements, a perfect shape fit of the micro-porous insulating material to the heating chamber can be provided. Providing a perfect shape fit of the micro-porous insulating material to the heating chamber can ensure better thermal insulation.

[0085] The first connecting element and the second connecting element can be configured as a male connecting element and a female connecting element, a shape-fit connecting element, a snap-fit connecting element, a bayonet connecting element, or a mixture thereof, or other commonly used connecting elements known to those skilled in the art. The first connecting element can include a male connecting element and the second connecting element can include a female connecting element. The first connecting element and the second connecting element can include a shape-fit connecting element. The first connecting element and the second connecting element can include a snap-fit connecting element. The first connecting element and the second connecting element can include a bayonet connecting element.

[0086] The micro-porous insulating material can be configured as a two-piece assembly. The two-piece assembly can include a first insulating element and a second insulating element. The first insulating element and the second insulating element can be in the form of, for example, hollow semi-cylindrical elements. The hollow semi-cylindrical elements can include mating first and second connecting elements. When connected, the hollow semi-cylindrical elements can form a single hollow tube. The inner diameter of the hollow tube can have the same dimensions as the outer diameter of the heating chamber. Thereby, convenient assembly can be ensured. However, a micro-porous insulating material formed as one 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 of the micro-porous insulating material with the heating chamber can improve the thermal insulation of the heating chamber.

[0087] The heating chamber can include a temperature sensor. The temperature sensor can be on top of the heating chamber. The micro-porous insulating material can have a shape that matches the temperature sensor. The micro-porous insulating material can have a cavity facing the temperature sensor. The micro-porous insulating material can completely enclose the heating chamber. The temperature sensor can be surrounded by the micro-porous insulating material. The temperature sensor can be sandwiched between the heating chamber and the micro-porous insulating material.

[0088] The heater assembly may further include a heating element. The heating chamber may include a heating element.

[0089] 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 arranged to completely coaxially surround the outer periphery of the wall of the heating chamber. The heating element may be arranged along at least a portion of the longitudinal axis of the heating chamber.

[0090] The heating element may include 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 a susceptor for induction heating. The electrically insulating substrate may be a flexible substrate.

[0091] The heating element may be flexible and may be wrapped around the heating chamber. The heating element may be disposed between the heating chamber and the heater housing.

[0092] The micro-porous insulating material may have a longitudinal extension that is the same as or greater than that of the heating element. Thereby, proper thermal insulation of the heat generated by the heating element can be ensured.

[0093] The micro-porous insulating material may extend around the heating element. The micro-porous insulating material may be in direct contact with the heating element.

[0094] In all aspects of the present disclosure, the heating element may include a resistive material. Suitable resistive materials include, but are not limited to: semiconductors, such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide), carbon, graphite, metals, metal alloys, and composite materials made of ceramic materials and metal materials. Such composite materials may include doped or undoped ceramics.

[0095] As described, in any aspect of the present disclosure, the heating element can be part of a heating chamber of a heater assembly for an aerosol generating device. The heater assembly can include an internal heating element or an external heating element or both an internal and an external heating element, where "internal" and "external" are with respect to the aerosol forming substrate. The internal heating element can take any suitable form. For example, the internal heating element can take the form of a heating blade. Alternatively, the internal heater can take the form of a sleeve or substrate having different conductive portions, or a resistive metal tube. Alternatively, the internal heating element can be one or more heating pins 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, tungsten, or alloy wires or heating plates. Optionally, the internal heating element can be deposited in or on a rigid carrier material. In one such embodiment, the resistive heating element can be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal can be formed as tracks on a suitable insulating material, such as a ceramic material, and then sandwiched between another insulating material, such as glass. The heater formed in this way can be used to both heat and monitor the temperature of the heating element during operation.

[0096] The external heating element can take any suitable form. For example, the external heating element can take the form of one or more flexible heating foils on a dielectric substrate (e.g., polyimide). The flexible heating foil can be shaped to conform to the perimeter of the substrate receiving cavity. Alternatively, the external heating element can take the form of a metal mesh or multiple metal meshes, a flexible printed circuit board, a molded interconnect device (MID), a ceramic heater, a flexible carbon fiber heater, or can be formed on a suitable shaped substrate using a coating technique (e.g., plasma vapor deposition). The external heating element can also be formed using a metal having a defined relationship between temperature and resistivity. In such an exemplary device, the metal can be formed as tracks between two layers of suitable insulating materials. The external heating element formed in this way can be used to both heat and monitor the temperature of the external heating element during operation.

[0097] Advantageously, the heating element heats the aerosol forming substrate by means of heat conduction. The heating element can at least partially contact the substrate or the carrier on which the substrate is placed. Alternatively, heat from the internal heating element or the external heating element can be conducted to the substrate by means of a heat conducting element.

[0098] During operation, the aerosol forming substrate can be fully contained within the aerosol generating device. In this case, the user can draw on the mouthpiece of the aerosol generating device. Alternatively, during operation, a smoking article containing the aerosol forming substrate can be partially contained within the aerosol generating device. In this case, the user can draw directly on the smoking article.

[0099] The heating element can be configured as an induction heating element. The induction heating element can include an induction coil and a susceptor. Generally, a susceptor is a material that can generate heat when penetrated by an alternating magnetic field. According to the present invention, the susceptor can be conductive or magnetic, or both conductive and magnetic. The alternating magnetic field generated by one or several induction coils heats the susceptor, and the susceptor then transfers the heat to the aerosol-forming substrate, causing the aerosol to form. The heat transfer can be mainly by heat conduction. This heat transfer is optimal if the susceptor is in close thermal contact with the aerosol-forming substrate. When an induction heating element is used, the induction heating element can be configured as an internal heating element as described herein or an external heater as described herein. If 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. If 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 the cavity or forms the side wall of the cavity.

[0100] The heating chamber can include a central region that includes the heating element. The term central region is with respect to the longitudinal direction. The heating chamber can further include a proximal region and a distal region. The proximal region and the distal region can be spaced apart from the heating element in the longitudinal direction. During use, the proximal region and the distal region can be colder than the central region of the heating chamber. A first connecting wall can contact the heating chamber in the proximal region, and a second connecting wall can contact the heating chamber in the distal region. Thus, during use, the first connecting wall and the second connecting wall can contact the heating chamber at the coldest points of the heating chamber. Thereby, the heat loss from the heating chamber to the connecting walls and the heater housing can be additionally reduced. The thermal insulation can be additionally improved.

[0101] The wall of the heating chamber can be made of stainless steel. This can beneficially enhance the effect that, during use, the proximal region and the distal region are colder than the central region of the heating chamber.

[0102] The thickness of the wall of the heater housing can be less than about 2 millimeters. The thickness of the wall of the heater housing can be less than 1.2 millimeters, preferably about 0.8 millimeters. The thickness of one or both of the first connecting wall and the second connecting wall can be less than 1.2 millimeters, preferably about 0.8 millimeters. With such a thin wall, the thermal mass of the heater housing can be minimized. This can additionally reduce the heat loss from the heating chamber.

[0103] The wall of the heater housing, and one or more of the first and second connecting walls, may be made of a material with low thermal conductivity. This can additionally reduce heat loss from the heating chamber. The wall of the heater housing may comprise or be made of a plastic material. The first and second connecting walls may comprise or be made of a plastic material. The plastic material may comprise one or two of polyaryletherketone (PAEK), polyetheretherketone (PEEK), and polyphenylene sulfone (PPSU). Preferably, the plastic material comprises polyphenylene sulfone (PPSU).

[0104] The inner side of the wall of the heater housing may comprise a metal coating. The inner side of one or both of the first and second connecting walls may comprise a metal coating. The metal coating may reduce the emissivity of the inner side 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 the thermal radiation emitted from the heating chamber. The metal coating may provide additional thermal insulation of the heating chamber relative to the exterior of the heater housing. The metal coating may be a low-emissivity metal coating. The metal coating may comprise one or more of aluminum, gold, and silver.

[0105] The present invention further relates to an aerosol-generating device comprising a heater assembly as described herein.

[0106] Preferably, the aerosol-generating device comprises a power supply device configured to supply power to the heating element. The power supply device preferably comprises a power source. Preferably, the power source is 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 need to be recharged. For example, the power source may have sufficient capacity to allow continuous generation of aerosol for a time period of about six minutes, or a multiple of six minutes. In another example, the power source may have sufficient capacity to allow a predetermined number of puffs or discontinuous activations of the heater assembly.

[0107] The power supply device may comprise control electronics. The control electronics may comprise a microcontroller. The microcontroller is preferably a programmable microcontroller. The circuit may comprise additional electronic components. The circuit may be configured to regulate the power supply to the heater assembly. Power may be supplied continuously to the heater assembly after system activation, or may be supplied intermittently, such as on a puff-by-puff basis. Power may be supplied to the heater assembly in the form of current pulses.

[0108] 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 the heating chamber. The aerosol-forming substrate may be part of an aerosol-generating article, and the aerosol-generating article may be configured to be at least partially inserted into the heating chamber.

[0109] As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form an aerosol. The volatile compounds can be released by heating or combusting the aerosol-forming substrate. As an alternative to heating or combustion, in some cases, the volatile compounds can be released by chemical reaction or by mechanical stimulation (such as ultrasound). The aerosol-forming substrate can be solid or liquid, or can include both solid and liquid components. The aerosol-forming substrate can be part of an aerosol-generating article.

[0110] The aerosol-forming substrate can be a solid aerosol-forming substrate. The aerosol-forming substrate can include both solid and liquid components. The aerosol-forming substrate can include a tobacco-containing material that contains volatile tobacco flavor compounds released from the substrate upon heating. The aerosol-forming substrate can include a non-tobacco material. The aerosol-forming substrate can include an aerosol-forming agent that aids in the formation of a dense and stable aerosol. Examples of suitable aerosol-forming agents are glycerol and propylene glycol.

[0111] As used herein, the term "aerosol-generating article" refers to an article that includes an aerosol-forming substrate capable of releasing volatile compounds that can form an aerosol. The aerosol-generating article can be disposable.

[0112] 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 can interact with one or both of an aerosol-generating article that includes an aerosol-forming substrate and a cartridge that includes an aerosol-forming substrate. In some examples, the aerosol-generating device can heat the aerosol-forming substrate to facilitate the release of volatile compounds from the substrate. An electrically-operated aerosol-generating device can include an atomizer, such as an electric heater, to heat the aerosol-forming substrate to form an aerosol.

[0113] As used herein, the term "aerosol-generating system" refers to a combination of an aerosol-generating device and an aerosol-forming substrate. When the aerosol-forming substrate forms part of an aerosol-generating article, the aerosol-generating system refers to a combination of the aerosol-generating device and the aerosol-generating article. In an aerosol-generating system, the aerosol-forming substrate and the aerosol-generating device cooperate to generate an aerosol.

[0114] A non-exhaustive list of non-limiting examples is provided below. Any one or more features of these examples can be combined with any one or more features of another example, embodiment, or aspect described herein.

[0115] Example A: A heater assembly for an aerosol-generating device, the heater assembly comprising:

[0116] A heating chamber for heating an aerosol-forming substrate;

[0117] A heater housing that is arranged around the heating chamber, wherein the heater housing is arranged to be radially spaced apart from the heating chamber, wherein the heater housing includes an airtight space, and wherein the airtight space includes a micro-porous insulating material.

[0118] Example B: The heater assembly according to Example A, further comprising a first connecting wall connecting the heating chamber and the heater housing and a second connecting wall connecting the heating chamber and the heater housing, wherein the airtight space is defined between the heating chamber, the heater housing, the first connecting wall, and the second connecting wall.

[0119] Example C: The heater assembly according to Example B, wherein the connecting wall is oriented perpendicular to the longitudinal axis of the heating chamber.

[0120] Example D: The heater assembly according to any one of the foregoing examples, wherein the airtight space is at ambient pressure.

[0121] Example E: The heater assembly according to any one of the foregoing examples, wherein the airtight space is at least partially filled with the micro-porous insulating material.

[0122] Example F: The heater assembly according to any one of the foregoing examples, wherein the airtight space is at least partially filled with a gaseous composition at ambient pressure.

[0123] Example G: The heater assembly according to any one of the foregoing examples, wherein the airtight space includes at least one air gap.

[0124] Example H: The heater assembly according to Example G, wherein the micro-porous insulating material is sandwiched between two air gaps in the radial direction.

[0125] Example I: The heater assembly according to any one of the foregoing examples, wherein the micro-porous insulating material is in direct contact with the heating chamber.

[0126] Example J: The heater assembly according to any one of the foregoing examples, wherein the micro-porous insulating material is in direct contact with the heater housing.

[0127] Example K: The heater assembly according to any one of the foregoing examples, wherein the micro-porous insulating material is in direct contact with the first connecting wall and the second connecting wall of Example B.

[0128] Example L: The heater assembly according to any one of the foregoing examples, wherein the micro-porous insulating material is in direct contact with the heating chamber, the heater housing, and the first connecting wall and the second connecting wall of Example B.

[0129] Example M: A heater assembly according to any one of the preceding examples, wherein the microporous insulating material is formed by a first insulating element including at least one first connecting element and a second insulating element including at least one second connecting element, and wherein the first connecting element and the second connecting element are configured as mating connecting elements.

[0130] Example N: A heater assembly according to Example M, wherein the first connecting element includes a convex connecting element and the second connecting element includes a concave connecting element.

[0131] Example O: A heater assembly according to Example M or N, wherein the first connecting element and the second connecting element include form - fitting connecting elements.

[0132] Example P: A heater assembly according to any one of Examples M to O, wherein the first connecting element and the second connecting element include snap - fit connecting elements.

[0133] Example Q: A heater assembly according to any one of Examples M to P, wherein the first connecting element and the second connecting element include bayonet connecting elements.

[0134] Example R: A heater assembly according to any one of the preceding examples, wherein the microporous insulating material has an elongated extension.

[0135] Example S: A heater assembly according to any one of the preceding examples, wherein the microporous insulating material extends parallel to the longitudinal axis of the heating chamber.

[0136] Example T: A heater assembly according to any one of the preceding examples, wherein the distance between the heating chamber and the heater housing is between 1.5 mm and 7 mm, preferably between 2 mm and 4 mm, preferably about 3.1 mm.

[0137] Example U: A heater assembly according to any one of the preceding examples, further comprising a heating element.

[0138] Example V: A heater assembly according to Example U, wherein the heating element is at least partially arranged around the heating chamber.

[0139] 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.

[0140] Example X: A heater assembly according to any one of Examples U to W, wherein the heating element is flexible and wraps around the heating chamber.

[0141] Example Y: The heater assembly according to any one of Examples U to X, wherein the heating element is arranged between the heating chamber and the heater housing.

[0142] Example Z: The heater assembly according to any one of Examples U to Y, wherein the heating element comprises one or more conductive tracks on an electrically insulating substrate.

[0143] Example AA: The heater assembly according to any one of the foregoing examples, wherein the ratio of the outer diameter of the heater housing to the outer diameter of the heating chamber is between 1.3 and 3.5, preferably between 1.5 and 2.5, more preferably about 2.0.

[0144] Example AB: The heater assembly according to any one of the foregoing examples, 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, more preferably less than 0.03 W / m·K at a temperature of 280 degrees Celsius.

[0145] Example AC: The heater assembly according to any one of the foregoing examples, wherein the thermal conductivity of the microporous insulating material increases by at most 40%, preferably at most 30%, more preferably at most 20% at a temperature of 280 degrees Celsius compared to its thermal conductivity at room temperature.

[0146] Example AD: The heater assembly according to any one of the foregoing examples, 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.

[0147] Example AE: The heater assembly according to any one of the foregoing examples, wherein the heating chamber has an elongated shape, preferably, wherein the heating chamber is a hollow tube.

[0148] Example AF: The heater assembly according to any one of the foregoing examples, wherein the heating chamber comprises: a central region that includes the heating element of Example U;

[0149] a proximal region; and

[0150] a distal region,

[0151] wherein the proximal region and the distal region are spaced apart from the heating element in a longitudinal direction, and

[0152] 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.

[0153] Example AG: A heater assembly according to any one of the preceding examples, wherein the inner side of the wall of the heater housing includes a metal coating, optionally, wherein the wall of the heating chamber includes stainless steel.

[0154] Example AH: A heater assembly according to any one of the preceding examples, wherein the thickness of the wall of the heater housing of claim 2 and one or more of the first connecting wall and the second connecting wall is less than 2 mm, preferably less than 1.2 mm, preferably about 0.8 mm.

[0155] Example AI: A heater assembly according to any one of the preceding examples, wherein the wall of the heater housing of Example B and one or more of the first connecting wall and the second connecting wall comprise a plastic material, preferably comprising polyaryletherketone (PAEK), polyetheretherketone (PEEK) or polyphenylsulfone (PPSU), more preferably comprising polyphenylsulfone (PPSU).

[0156] Example AJ: An aerosol generating device comprising a heater assembly according to any one of the preceding examples.

[0157] Example AK: An aerosol generating system comprising the aerosol generating device according to Example AJ and an aerosol-forming substrate configured to be at least partially received in the heating chamber.

[0158] Features described with respect to one embodiment may equally apply to other embodiments of the present invention. Description of the Drawings

[0159] The present invention will be further described only by way of example with reference to the accompanying drawings, in which:

[0160] Figure 1 An embodiment of a heater assembly for an aerosol generating device is shown;

[0161] Figure 2 An embodiment of the heating chamber of the heater assembly is shown;

[0162] Figure 3 An embodiment of a heater assembly for an aerosol generating device is shown;

[0163] Figure 4 An embodiment of a heater assembly for an aerosol generating device is shown;

[0164] Figure 5 An embodiment of a heater assembly for an aerosol generating device is shown;

[0165] Figure 6 An embodiment of a heater assembly for an aerosol generating device is shown;

[0166] Figure 7 Shows an embodiment of a microporous insulating material for a heater assembly of an aerosol generating device;

[0167] Figure 8 Shows an embodiment of an aerosol generating device;

[0168] Figure 9 Shows an embodiment of an aerosol generating device;

[0169] Figure 10 Shows an embodiment of an aerosol generating device including aerosol insulation. Detailed Description

[0170] Figure 1 Schematically shows 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 wall 14 of the heating chamber, which defines a cavity for inserting the aerosol-forming substrate. The wall 14 of the heating chamber forms a hollow tube. The heater assembly 10 further includes a heater housing. The heater housing is arranged coaxially around the heating chamber 12. The heater housing includes a cylindrical wall 16 of the heater housing. The heater housing is further arranged to be radially spaced from the heating chamber 12 by a distance d. The distance d is measured in the radial direction between the outer diameter of the hollow tube formed by the wall 14 of the heating chamber and the inner diameter of the cylindrical wall 16 of the heater housing. The wall 14 of the heating chamber and the wall 16 of the heater housing have a matching shape. Thus, the distance d is constant along the longitudinal axis of the heating chamber 12.

[0171] The heater assembly 10 further includes a first connecting wall 18 at the proximal end of the heater assembly 10. The heater assembly 10 further includes a second connecting wall 20 at the distal end of the heater assembly 10. The first connecting wall 18 and the second connecting wall 20 are oriented perpendicular to the longitudinal axis of the heating chamber 12. The heater assembly 10 further includes an airtight space 22. The airtight space 22 is defined between the wall 14 of the heating chamber, the wall 16 of the heater housing, and the first connecting wall 18 and the second connecting wall 20.

[0172] Figure 2An embodiment of the heating chamber 12 is shown. 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 wall of the heating chamber 14 is a metal tube, preferably a stainless steel tube. The heating element is flexible and wraps around the metal tube. The heating element includes a conductive heating track 24 on an electrically insulating flexible substrate 26. In the illustrated embodiment, the proximal edge portion and the distal edge portion of the flexible substrate 26 are not covered by the heating track 24. In other embodiments, different regions or even the entire surface of the flexible substrate 26 may be covered by the heating track 24. The proximal region 28 and the distal region 30 of the heating chamber 12 are spaced apart from the heating element in the longitudinal direction.

[0173] Figure 3 An embodiment of the heater assembly 10 including Figure 2 the heating chamber 12 is shown. The heating element is disposed between the heating chamber 12 and the heater housing.

[0174] The first connecting wall 18 and the second connecting wall 20 sealably connect the wall 16 of the heater housing to the wall 14 of the heating chamber, thereby hermetically enclosing the hermetic space 22.

[0175] The first connecting wall 18 and the second connecting wall 20 contact the heating chamber 12 in the proximal region 28 and the distal region 30, respectively. The first connecting wall 18 and the second connecting wall 20 contact the heating chamber 12 at a position spaced apart from the heating element. Thus, the first connecting wall 18 and the second connecting wall 20 contact the heating chamber at the coldest point of the heating chamber 12 when heated during use. Thereby, heat loss due to heat transfer from the heating chamber 12 to the connecting walls 18, 20 and the heater housing via heat conduction is additionally reduced. Thermal insulation can be additionally improved.

[0176] The hermetic space 22 includes a microporous insulating material 32. The microporous insulating material 32 can be, for example, MICROSIL microporous insulation from ZIRCAR Ceramics, Inc.; and one or other commercially available microporous insulating materials in Microtherm 1000 grade from Unifrax I LLC and Promat Inc. Particularly preferably, the microporous insulating material 32 contains silica aerogel and a polymer resin, preferably consists of silica aerogel and a polymer resin. Particularly preferably, the microporous insulating material 32 contains up to 30% of the polymer resin, while the remainder (1% to 99%) of the microporous insulating material 32 is silica aerogel.

[0177] In Figure 3In the embodiment shown, the entire hermetic space 22 is filled with a microporous insulation material 32. The microporous insulation material 32 contacts the walls 14 of the heating chamber, the heating rails 24, the first connecting wall 18 and the second connecting wall 20, and the walls 16 of the heater housing. Although not shown, Figure 3 the microporous insulation material 32 shown in may also include one or more air gaps extending in a direction parallel to the longitudinal axis of the aerosol-generating device. Those air gaps may directly contact the walls 14 of the heating chamber, the walls 16 of the heater housing, or the first connecting wall 18 and the second connecting wall 20. Those air gaps may have a shorter longitudinal extension than the microporous insulation material 32.

[0178] Figure 4 , 5 and 6 show alternative embodiments in which the hermetic space 22 is only partially filled with the microporous insulation material 32. The main elements are similar to Figure 3 the heater assembly of. In Figure 4 , 5 and 6, the hermetic space 22 includes at least one additional air gap 34. In all these embodiments, the microporous insulation material 32 contacts the first connecting wall 18 and the second connecting wall 20. However, the microporous insulation material 32 may alternatively contact only one of the first connecting wall 18 and the second connecting wall 20. Preferably, the microporous insulation material 32 contacts only the first (proximal) connecting wall 18. The microporous insulation material 32 may be mounted on the first connecting wall 18 and the second connecting wall 20.

[0179] In Figure 4 , a heater assembly is shown in which the air gap 34 extends around the heating chamber 12. The microporous insulation material 32 extends around the air gap 34 at a radial distance from the heating chamber 12. The microporous insulation material 32 directly contacts the walls 16 of the heater housing.

[0180] Figure 5 shows an alternative embodiment in which the microporous insulation material 32 directly contacts the heating chamber 12. The air gap 34 extends around the microporous insulation material 32 at a radial distance from the heating chamber 12. The air gap 34 directly contacts the walls 16 of the heater housing.

[0181] Figure 6 shows an alternative embodiment in which the hermetic space 22 includes two air gaps 34. One air gap 34 extends around the heating chamber 12 and is directly connected to the heating chamber 12. The microporous insulation material 32 extends at a radial distance from that air gap 34. Subsequently, there is an additional air gap 34 which extends around the microporous insulation material 32 at a radial distance from the microporous insulation material 32. The microporous insulation material 32 is sandwiched between the two air gaps 34 in the radial direction.

[0182] Figure 3 , 4 , the hermetic space 22 shown in FIGS. 5 and 6 can be filled with the micro-porous insulating material 32 at different ratios. For example, half of the volume of the hermetic space 22 is filled with the micro-porous insulating material 32. However, other ratios are also possible. For example, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% of the volume of the hermetic space 22 is filled with the micro-porous insulating material 32.

[0183] Figure 7 A two-piece assembly of the micro-porous insulating material 32 is shown. Figure 3 , 4 , the heater assemblies 10 depicted in FIGS. 5 and 6 can all include Figure 7 a two-piece assembly. However, the two-piece assembly is particularly suitable for Figure 3 and 5 embodiments. As can be seen in Figure 7 , the micro-porous insulating material 32 is formed by 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 connecting the two first insulating elements 36 and the second insulating element 38, the first connecting element 40 and the second connecting element 42 are connected to each other. 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 Figure 7 . However, other shapes and configurations are possible. When connected, the hollow semi-cylindrical design provides a hollow tube. The hollow tube can have an inner diameter that is the same as the outer diameter of the heating chamber 12. The hollow tube can also have an inner diameter that is the same as the outer diameter of the heating chamber 12 and the heating rail 24 combined together. Through this two-piece assembly, the micro-porous insulating material 32 can have a perfect fit with the heating chamber 12 and the heating rail 24 surrounding the heating chamber. Additionally, if the heating chamber includes a temperature sensor (not shown), the inner shape of the micro-porous insulating material 32 can be configured to fit the temperature sensor. The micro-porous insulating material 32 can include a cavity facing the sensor. The cavity can have the same volume and opposite shape as that of the temperature sensor. The micro-porous insulating material 32 can completely enclose the heating chamber 12 and the heating rail 24. Using a hollow tube with only a single element including the micro-porous insulating material 32 may not provide such a perfect fit with the heating chamber 12.

[0184] Figure 8 shows including Figure 3An embodiment of an aerosol-generating device having a heater assembly 10. The aerosol-generating device further includes a power supply device. The power supply device includes a power source 44 and control electronics 46. The power source 44 can be a rechargeable battery. In Figure 8 In an embodiment, the wall 16 of the heater housing forms part of the outer housing 48 of the aerosol-generating device.

[0185] At the opening 50, the aerosol-forming substrate can be at least partially inserted into the heating chamber 12. The aerosol-forming substrate can be part of an aerosol-generating article.

[0186] Figure 9 An embodiment of an aerosol-generating device including Figure 3 the heater assembly 10 is shown. Different from Figure 8 the embodiment of Figure 9 In an embodiment, the heater assembly 10 is arranged within a separate outer housing 48 of the aerosol-generating device.

[0187] Figure 10 An embodiment of an aerosol-generating device including a heater assembly 10 arranged adjacent to the proximal end of the aerosol-generating device is shown. The flexible substrate 26 and the heating track 24 of the heating assembly 10 are arranged around the heating chamber 12. The microporous insulating material 32 is arranged around and in contact with the flexible substrate 26 and the heating track 24. The microporous insulating material 32 comprises 1% to 99% aerogel and up to 30% polymer resin. Due to the provision of the polymer resin, the microporous insulating material 32 is provided as a flexible layer such that the microporous insulating material 32 can wrap around the flexible substrate 26 at the heating track 24. To hold the microporous insulating material 32 in place, a polyimide layer 52 is arranged to surround the microporous insulating material 32. The polyimide layer 52 is a flexible layer. As Figure 10 shown, the polyimide layer 52 can partially cover the microporous insulating material 32. In Figure 10 the embodiment shown, 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 beyond the polyimide layer 52 in the proximal direction. 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 beyond the polyimide layer 52 in the distal direction. Alternatively, the polyimide layer 52 can completely cover the microporous insulating material 32.

[0188] An air gap 54 is provided surrounding the polyimide layer 52. The polyimide layer 52 as well as the air gap 54 are both provided within the hermetic space 22. Radially outside the air gap 54, the wall 16 of the heater housing is provided.

[0189] 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 yet another alternative, the microporous insulating material 32 may be in direct contact with both the first connecting wall 18 and the second connecting wall 20.

[0190] In Figure 10 the embodiment shown, the heater housing (more particularly, the wall 16 of the heater housing) is mounted on an internal frame 56 within the housing 48 of the aerosol-generating device. The internal frame 56 may hold other components of the aerosol-generating device such as the heating chamber 12.

Claims

1. A heater assembly for an aerosol generating device, the heater assembly comprising: a heating chamber for heating an aerosol-forming substrate; a heater housing arranged around the heating chamber, wherein the heater housing is arranged to be radially spaced apart from the heating chamber, wherein the heater housing includes an airtight space, and wherein the airtight space includes a microporous insulating material, wherein the microporous insulating material comprises an aerogel.

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

3. The heater assembly according to any one of the preceding claims, wherein the microporous insulating material comprises a polymer resin.

4. The heater assembly according to claim 3, wherein the microporous insulating material comprises between 0.5 wt% and 50 wt%, preferably between 0.7 wt% and 40 wt%, more preferably between 1 wt% and 30 wt% of the polymer resin.

5. The heater assembly according to claim 3 or 4, wherein the microporous insulating material comprises between 1 wt% and 50 wt%, preferably between 5 wt% and 45 wt%, more preferably between 10 wt% and 40 wt%, more preferably between 20 wt% and 40 wt%, most preferably approximately 30 wt% of the polymer resin.

6. The heater assembly according to any one of the preceding claims, wherein the microporous insulating material comprises between 1 wt% and 99 wt%, preferably between 50 wt% and 90 wt%, more preferably between 60 wt% and 80 wt%, most preferably approximately 70 wt% of the aerogel.

7. The heater assembly according to any one of the preceding claims, wherein the microporous insulating material is flexible.

8. The heater assembly according to any one of the preceding claims, wherein the airtight space includes a polyimide layer.

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

10. The heater assembly according to claim 9, wherein a gap is provided between the polyimide layer and the heater housing.

11. The heater assembly according to any one of the preceding claims, wherein the microporous insulating material is arranged in direct contact with the heating chamber.

12. The heater assembly according to any one of the preceding claims, wherein the heater assembly further comprises a heat dissipation element arranged at least partially around 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 according to claim 12, wherein the heat dissipation element is arranged between the microporous insulating material and the heating chamber and on the outer periphery of the heating chamber.

14. An aerosol generating device, the aerosol generating device comprising a heater assembly according to any one of the preceding claims.

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

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