Heater assembly with fasteners

Abstract

A heater assembly (1) for an aerosol generating device, the heater assembly comprising a first heater casing (2) including an air inlet, a second heater (4) casing including an aerosol outlet (10), and a heating chamber (6) for heating an aerosol-forming substrate, the heating chamber (6) being in fluid communication with both the air inlet and the aerosol outlet (10) to define an airflow path through the heater assembly (1), the heating chamber (6) being configured to include a first heater casing (2) and a second heater casing (4) including an aerosol outlet (10). The first heater casing (2) and the second heater casing (4) are disposed between the first heater casing (2) and the second heater casing (4), and the first heater casing (2) and the second heater casing (4) are attached to one another by fasteners (26), which are configured to apply an axial force to the first heater casing (2) and the second heater casing (4) to urge axially opposite inner surfaces of the first heater casing (2) and the second heater casing (4) into sealing engagement with respective axially opposite end faces of the heating chamber (6) to seal the airflow path.

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 comprising the heater assembly. Specifically, but not exclusively, the present disclosure relates to a handheld electrically operated aerosol generating device for heating an aerosol forming substrate to generate an aerosol and delivering the aerosol into a user's mouth. The invention also relates to an aerosol generating system comprising an aerosol generating device and an aerosol forming substrate.

Background Art

[0002] Aerosol generating devices that heat an aerosol forming substrate to generate an aerosol without burning the aerosol forming substrate are known in the art. The aerosol forming substrate is typically provided within an aerosol generating article together with other components such as a filter. The aerosol generating article may have a rod shape for insertion of the aerosol generating article into the heating chamber of the aerosol generating device. The heating element is typically disposed within or around the heating chamber to heat the aerosol forming substrate after the aerosol generating article has been inserted into the heating chamber of the aerosol generating device.

[0003] The heating chamber is disposed within the housing of the aerosol generating device and may form part of the airflow path through the aerosol generating device. In an attempt to prevent aerosol from leaking out of the airflow path and entering other parts of the aerosol generating device, which could damage the electronics of the device, seals are provided around the airflow path and between the heating chamber and the housing. The seal may be disposed in direct contact with the heating chamber and as a result is generally formed from a heat resistant polymer such as silicone or polysiloxane. However, exposing such a polymer seal to the heating temperature of the heating chamber may result in the generation of undesirable by-products that can contaminate the aerosol. Further, such heating temperatures can degrade the seal over time.

[0004] To heat the heating chamber, the aerosol generator may include a flexible heating element arranged around the heating chamber. To allow direct contact between the seal and the heating chamber and reduce heating of the seal, attempts have been made to position the seal at a distance from the heating element, for example, at the downstream end of the heating chamber. However, this may necessitate compromising the overall dimensions of the aerosol generator through the use of a long heating chamber, increasing the energy consumption of the heating chamber and reducing the efficiency of the aerosol generator. Furthermore, increasing the length of the heating chamber may result in the heating chamber surrounding other components of the aerosol generating article, such as filters, which may be indirectly heated through heat conduction via the heating chamber. Undesirably, heating the filters wastes energy.

[0005] As an alternative to increasing the length of the heating chamber, the length of the heating element surrounding the heating chamber may be reduced. However, this may result in a portion of the aerosol-forming substrate not being covered or surrounded by the heating element, and consequently, heat may need to travel a longer distance along the length of the heating chamber to heat this portion of the aerosol-forming substrate compared to the relatively short distance traveled through the thickness of the heating chamber wall. Therefore, the portion of the aerosol-forming substrate not surrounded by the heating element may not be heated as effectively as the portion surrounded by the heating element. As a result, the portion of the aerosol-forming substrate not surrounded by the heating element may be colder than the portion surrounded by the heating element, which may lead to premature condensation of aerosols in the colder portion. This may reduce the amount of aerosol delivered to the user.

[0006] A further drawback of using a polymer seal between the heating chamber and the device housing is that the polymer seal provides a heat conduction path that transfers heat away from the heating chamber to the material surrounding the heating chamber. This heat loss reduces the amount of heat available to heat the aerosol-forming substrate, thus decreasing the efficiency of the aerosol generator.

[0007] It is desirable to provide a heater assembly for an aerosol generator in which the sealing of the airflow path is improved. It is also desirable to provide a heater assembly for an aerosol generator that is more energy efficient and improves the delivery of aerosols to the user. [Overview of the project]

[0008] According to one embodiment of the present disclosure, a heater assembly for an aerosol generator is provided. The heater assembly may comprise a first heater casing. The first heater casing may include an air intake. The heater assembly may comprise a second heater casing. The second heater casing may include an aerosol outlet. The heater assembly may comprise a heating chamber for heating an aerosol-forming substrate. The heating chamber may be in fluid communication with the air intake. The heating chamber may be in fluid communication with the aerosol outlet. The heating chamber may be in fluid communication with both the air intake and the aerosol outlet to define an airflow path through the heater assembly. The heating chamber may be disposed between the first heater casing and the second heater casing. The first and second heater casings may be attached to each other by fasteners. The fasteners may be configured to apply axial force to the first and second heater casings. The fasteners may be configured to seal the airflow path by biasing the axially opposite inner surfaces of the first and second heater casings to engage in a sealing manner with the axially opposite end faces of the respective heating chambers.

[0009] According to one embodiment of the present disclosure, a heater assembly for an aerosol generator is provided. The heater assembly comprises a first heater casing including an air intake. The heater assembly comprises a second heater casing including an aerosol outlet. The heater assembly comprises a heating chamber for heating an aerosol-forming substrate. The heating chamber is in fluid communication with both the air intake and the aerosol outlet to define an airflow path through the heater assembly. The heating chamber is disposed between the first heater casing and the second heater casing. The first and second heater casings are attached to each other by fasteners, which are configured to apply axial force to the first and second heater casings, thereby biasing the axially opposite inner surfaces of the first and second heater casings to engage in a sealing engagement with the axially opposite end faces of the respective heating chambers, thereby sealing the airflow path.

[0010] Advantageously, the embodiments described above of this disclosure do not require a polymer seal because the airflow path is sealed by direct engagement between the end face of the heating chamber and the inner surfaces of the first and second heating cases. Therefore, no undesirable byproducts that may be released by heating of the polymer seal are generated.

[0011] A further advantage of sealing the airflow path using direct engagement between the end face of the heating chamber and the inner surfaces of the first and second heating cases is that no space is required at the end of the heating chamber to allow direct contact between the polymer seal and the heating chamber. For example, any space at one or more ends of the heating chamber to avoid direct contact between the heating element and the surrounding heater casing can be greatly reduced. This means that a shorter heating chamber can be used, and a larger proportion of the length of the heating tube can be heated. This allows for more efficient heating of the aerosol-forming substrate.

[0012] Advantageously, the cross-sectional area available for heat conduction away from the heating chamber is significantly reduced. The heating chamber typically has a wall thickness less than the thickness of the polymer seal, for example, 100 microns for 2 millimeters and 100 microns for 2 millimeters. Therefore, the area of ​​the end walls of the heating chamber in contact with the first and second heater casings is conventionally less than the area of ​​the polymer seal surrounding the heating chamber. As a result, the amount of heat loss to the aerosol generator portion surrounding the heating chamber is reduced.

[0013] As used herein, the term “axial force” refers to a force acting parallel to the axis of the heater assembly. For example, a force may act parallel to the longitudinal axis of the heater assembly.

[0014] As used herein, the terms “distal,” “upstream,” “proximal,” and “downstream” describe the relative positions of components or parts of components of an aerosol generating device and an aerosol generating article. The aerosol generating articles and devices according to this disclosure have a proximal end through which the aerosol exits for delivery to the user during use, and a distal end on the opposite side. The proximal end of the aerosol generating article and device may also be called the mouth end. During use, the user inhales the proximal end of the aerosol generating article to inhale the aerosol generated by the aerosol generating article or device. The terms upstream and downstream refer to the direction of movement of the aerosol through the aerosol generating article or aerosol generating device when the user inhales the proximal end of the aerosol generating article. The proximal end of the aerosol generating article is downstream of the distal end of the aerosol generating article. The proximal end of the aerosol generating article may also be called the downstream end of the aerosol generating article, and the distal end of the aerosol generating article may also be called the upstream end of the aerosol generating article.

[0015] The aerosol outlet may be an opening for receiving an aerosol-generating article. The aerosol may exit through the opening via the aerosol-generating article received in the heating chamber.

[0016] At least one of the first and second heater casings may include an internal cavity. The internal cavity may surround a heating chamber. The length of the heating chamber may be greater than the length of the internal cavity. Advantageously, by making the length of the heating chamber greater than the length of the internal cavity, elastic deformation is induced in at least one of the first and second heater casings. This elastic deformation is maintained by fasteners, which apply axial forces to the first and second heater casings, providing a sealing engagement between the first and second heater casings and the heating chamber, thereby sealing the airflow path.

[0017] The first heater casing may include an internal cavity. The internal cavity may surround the heating chamber. The length of the heating chamber may be greater than the length of the internal cavity.

[0018] The second heater casing may include an internal cavity. The internal cavity may surround the heating chamber. The length of the heating chamber may be greater than the length of the internal cavity.

[0019] The first heater casing may include a first internal cavity. The second heater casing may include a second internal cavity. The first and second internal cavities together may surround a heating chamber. The length of the heating chamber may be greater than the combined length of the first and second internal cavities.

[0020] The length of the heating chamber may be greater than the length of the internal cavity within the heater assembly in its unassembled state.

[0021] The length of the internal cavity may include the depth of the recess formed on the inner surface of at least one of the internal cavities of the first and second heater casings.

[0022] As another method, the length of the internal cavity may include only the length of the internal cavity from the first end of the internal cavity to the second end of the internal cavity of one of the first and second heater casings.

[0023] The length of the heating chamber may be about 0.05 percent to about 8.5 percent longer than the internal cavity, preferably about 0.5 percent to 5.0 percent longer than the internal cavity, more preferably about 1.3 percent to about 3.1 percent longer than the internal cavity. These ranges have been found to be appropriate for inducing elastic deformation of at least one of the first and second heater casings.

[0024] The length of the heating chamber may be about 0.05 millimeter to about 1.0 millimeter longer than the internal cavity, preferably about 0.2 millimeter to about 0.4 millimeter longer than the internal cavity. These ranges have been found to be appropriate for inducing elastic deformation of at least one of the first and second heater casings.

[0025] The first and second heater casings may enclose the heating chamber.

[0026] At least one of the first and second heater casings may include a material having a tensile elastic modulus or Young's modulus of less than 6 gigapascals, preferably less than 5 gigapascals, more preferably less than 4 gigapascals. These values of the tensile elastic modulus are typically smaller than the tensile elastic modulus of the material of the heater chamber, which means that at least one of the first and second heater casings elastically deforms preferentially over the heating chamber since the heating chamber is made of a material stiffer than the first and second heater casings. These values of the tensile elastic modulus have also been found to provide an appropriate amount of elastic deformation.

[0027] The heater chamber can include a material having a tensile modulus or Young's modulus of greater than about 100 gigapascals, preferably greater than about 150 gigapascals, more preferably greater than or equal to about 190 gigapascals. The heater chamber can include a material having a tensile modulus or Young's modulus of from about 100 gigapascals to about 250 gigapascals, preferably from about 150 gigapascals to about 220 gigapascals, more preferably from about 190 gigapascals to about 205 gigapascals.

[0028] At least one of the first and second heater casings can include a material having a glass transition temperature greater than 130 degrees Celsius. At least one of the first and second heater casings can include a material having a melting temperature greater than 280 degrees Celsius. These properties help maintain the structural stability of the material at the temperatures it experiences during heating and help reduce the likelihood of unwanted by-products being formed.

[0029] At least one of the first and second heater casings can include a material having a Shore hardness of less than 90A as determined by technical standard ISO868 type A.

[0030] Preferably, at least one of the first and second heater casings can include a material that can be injection molded.

[0031] At least one of the first and second heater casings can include a polymer. The polymer has been found to be a particularly suitable material due to its elastic properties.

[0032] The first and second heater casings may contain any suitable material or combination of materials. Examples of suitable materials include plastics, composite materials containing one or more materials, or thermoplastic resins suitable for food or pharmaceutical applications, such as polypropylene, polyether ether ketone (PEEK), polyphenylsulfone (PPSU), and polyethylene. Preferably, at least one of the first and second heater casings contains PEEK or PPSU.

[0033] At least one of the first and second heater casings may include a chamfered or inclined edge disposed on the inner surface of at least one of the first and second heater casings for axially aligning the heating chamber. Advantageously, the chamfered or inclined edge helps to precisely position the heating chamber within the first and second heater casings.

[0034] Fasteners may include threaded fasteners or snap-fit ​​fasteners. These have been found to be suitable types of fasteners for mounting the first and second heater casings together. Snap-fit ​​fasteners or connectors have been found to have several additional advantages. For example, snap-fit ​​fasteners have a reduced profile compared to other types of fasteners, which can help reduce the dimensions of the heater assembly. Snap-fit ​​fasteners also apply a constant amount of axial force that cannot be changed, which can help achieve balanced alignment of the first and second heater casings. Furthermore, snap-fit ​​fasteners simplify manufacturing because they require only a single press-fit action to mount the first and second heater casings. Additionally, snap-fit ​​fasteners can be formed integrally with the first and second heater casings, reducing the number of parts required for mounting.

[0035] The heater assembly may include a plurality of fasteners. The first and second heater casings may be attached to each other by a plurality of fasteners. The plurality of fasteners may be spaced symmetrically around the outer circumference or outer surface of the first and second heater casings. This arrangement helps to apply a constant pressure between the end faces of the first and second heater casings that are in contact with each other, around the entire circumference of the first and second heater casings. As a result of this constant pressure, a constant sealing pressure is generated between the contact surface of the heating chamber and the first and second heater casings around the entire circumference of the tubular heating chamber, improving the seal. The heater assembly may include at least two fasteners arranged on opposite sides of each other.

[0036] The first and second heater casings may be radially spaced apart from the heating chamber, defining a hollow air space around the heating chamber. Advantageously, the hollow air space helps to insulate the heating chamber, which helps to reduce heat loss from the heating chamber and also helps to reduce heat transfer from the heater assembly to the outside.

[0037] The first heater casing may have airflow channels. The airflow channels of the first heater casing may be in fluid communication with an air intake. The second heater casing may have airflow channels. The airflow channels of the second heater casing may be in fluid communication with an aerosol outlet. The heating chamber may have airflow channels. The airflow channels of the heating chamber may pass through the length of the heating chamber. The airflow channels of the first heating casing, the second heater casing, and the heating chamber may be in fluid communication with each other to define an airflow path through the heater assembly.

[0038] The heating chamber may include a tubular heating chamber. The diameter of the tubular heating chamber at the first end may be greater than the diameter along the length of the tubular heating chamber. The diameter of the tubular heating chamber at the second end may be greater than the diameter along the length of the tubular heating chamber. The diameter of the tubular heating chamber at each end may be greater than the diameter in the region between the two ends of the tubular heating chamber.

[0039] Advantageously, by making the diameter of one or both ends of the tubular heating chamber larger than, for example, the diameter of the tubular heating chamber along the length of the heating chamber in the region between the two ends of the tubular heating chamber, larger manufacturing tolerances for the heating chamber and other components of the heater assembly are possible. In particular, larger radial or lateral tolerances are possible. As used herein, the terms “radial tolerance” or “lateral tolerance” are used to describe manufacturing tolerances in a direction substantially perpendicular to the main longitudinal axis or length of the heater assembly or aerosol generator, for example, tolerances that result in components being wider or narrower than their specified design width, or having a diameter larger or smaller than their specified design diameter. Radial or lateral tolerances are sometimes referred to as “horizontal tolerances.”

[0040] Advantageously, by making the diameter of the end of the tubular heating chamber larger than that of the rest of the tubular heating chamber, the inner diameter at one or both ends of the tubular heating chamber becomes larger than the inner diameter of the other components of the heater assembly with which the tubular heating chamber engages, namely the airflow paths in the first and second heater casings. This helps to avoid the end face of the tubular heating chamber protruding or penetrating into the internal space of the airflow path, which could damage the aerosol-generating article when it is received into the heating chamber via the airflow path, thus avoiding a situation where the end face of the tubular heating chamber is too small to provide a sealing engagement with the other components. This arrangement also allows for larger radial or lateral tolerances in the other components, which will be described in more detail below.

[0041] The outer diameter of one or both ends of the tubular heating chamber may be up to 20 percent larger, preferably up to 15 percent larger, more preferably up to 12 percent larger, and even more preferably up to 8 percent larger than the outer diameter of the portion of the tubular heating chamber between the two ends of the tubular heating chamber. The outer diameter of one or both ends of the tubular heating chamber may be 1 to 20 percent larger, 1 to 15 percent larger, 1 to 12 percent larger, or 1 to 8 percent larger than the outer diameter of the portion of the tubular heating chamber between the two ends of the tubular heating chamber.

[0042] One or both ends of the tubular heating chamber may have an outer diameter of 7.5 mm to 9.0 mm, preferably 8.0 mm to 8.5 mm, more preferably about 8.4 mm. The portion of the tubular heating chamber between the two ends may have an outer diameter of 6.5 mm to 8.0 mm, preferably 7.0 mm to 8.0 mm, more preferably about 7.5 mm.

[0043] The inner diameter of the heating chamber may substantially correspond to or be substantially equal to the outer diameter of the aerosol generating article. In some embodiments, the inner diameter of the heating chamber may be slightly smaller than the outer diameter of the aerosol generating article so that the aerosol generating article is compressed within the heating chamber. For example, the outer diameter of the aerosol generating article may be about 7.4 millimeters, and the inner diameter of the heating chamber may be about 7.3 millimeters. The length of the heating chamber may substantially correspond to or be substantially equal to the length of the aerosol-forming substrate provided within the aerosol generating article.

[0044] At least one end portion of the tubular heating chamber may be flared or funnel-shaped. Portions of the tubular heating chamber at both ends may be flared or funnel-shaped. The axial length of the flared or funnel-shaped end portion of the tubular heating chamber may be 0.5 percent to 10 percent of the total length of the tubular heating chamber, preferably 1 percent to 5 percent of the total length of the tubular heating chamber, and more preferably about 3.3 percent of the total length of the tubular heating chamber.

[0045] The axial length of the flared or funnel-shaped end portion of the tubular heating chamber may be 0.2 mm to 2 mm, preferably 0.4 mm to 1 mm, and more preferably about 0.5 mm. The flared or funnel-shaped end portion or multiple end portions of the tubular heating chamber may be positioned at an angle of 30 to 60 degrees, 40 to 50 degrees, or about 45 degrees with respect to the longitudinal axis of the heating chamber or heater assembly. In some preferred embodiments, the flared or funnel-shaped end portion or multiple end portions of the tubular heating chamber may be positioned at an angle of less than 50 degrees, preferably less than 40 degrees, or more preferably less than 30 degrees with respect to the longitudinal axis of the heating chamber or heater assembly. Advantageously, by providing the flared or funnel-shaped end portion or multiple end portions of the tubular heating chamber at an angle of less than 30 degrees with respect to the longitudinal axis of the heating chamber or heater assembly, optimal rigidity can be provided to the flared or funnel-shaped end portion or multiple end portions of the tubular heating chamber in the direction of the longitudinal axis of the heating chamber or heater assembly.

[0046] At least one end or end portion of the tubular heating chamber may have a stepped profile or be tapered. Portions of the tubular heating chamber at both ends may have a stepped profile or be tapered. The axial length of the stepped or tapered end portion of the tubular heating chamber may be 0.5 percent to 10 percent of the total length of the tubular heating chamber, preferably 1 percent to 5 percent of the total length of the tubular heating chamber, and more preferably about 3.7 percent of the total length of the tubular heating chamber. To avoid sharp edges and stress concentration, it is preferable to provide a radius between the stepped or tapered portion.

[0047] The axial length of the flared or funnel-shaped end portion of the tubular heating chamber may be 0.2 mm to 2 mm, preferably 0.4 mm to 1 mm, and more preferably about 0.5 mm.

[0048] The tubular heating chamber may have a tubular wall thickness of 0.05 mm to 1.00 mm, preferably 0.05 mm to 0.50 mm, and more preferably about 0.10 mm.

[0049] The heating chamber can be made from any suitable material, including, but not limited to, ceramics, metals, or metal alloys. An example of a suitable material is stainless steel.

[0050] The heater assembly may include at least one electric heating element for heating the aerosol-forming substrate. The heater assembly may include multiple electric heating elements. The electric heating elements or multiple electric heating elements may be arranged around the outer surface of the heating chamber or surround the outer surface. The electric heating elements or multiple electric heating elements may be arranged around the inner surface of the heating chamber or surround the inner surface. The electric heating elements or multiple electric heating elements may be part of the heating chamber or integrated with the heating chamber.

[0051] An electric heating element or a set of electric heating elements may include an electrically resistive material. Suitable electrically resistive materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilide), carbon, graphite, metals, alloys, and composite materials made of ceramic and metallic materials. Such composite materials may include doped or undoped ceramics. An example of a suitable doped ceramic is doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable metal alloys include stainless steel, nickel-containing alloys, cobalt-containing alloys, chromium-containing alloys, aluminum-containing alloys, titanium-containing alloys, zirconium-containing alloys, hafnium-containing alloys, niobium-containing alloys, molybdenum-containing alloys, tantalum-containing alloys, tungsten-containing alloys, tin-containing alloys, gallium-containing alloys, manganese-containing alloys, gold-containing alloys, and iron-containing alloys, as well as nickel, iron, cobalt, stainless steel-based superalloys, Timetal®, Kanthal®, and other iron-chromium-aluminum alloys, and iron-manganese-aluminum alloys. In composite materials, the electrically resistive material may be embedded in an insulating material, encapsulated in an insulating material, or coated with an insulating material, depending on the required energy transfer dynamics and external physicochemical properties, or vice versa.

[0052] One or more heating elements may be formed using a metal or metal alloy having a clear relationship between temperature and resistivity. Heating elements formed in this manner may be used both for heating the heating element and for monitoring the heating element's temperature during operation.

[0053] The heating element may be placed in or on a rigid carrier material or substrate. The heating element may be placed in or on a flexible carrier material or substrate. The heating element may be formed as a track on a suitable insulating material such as ceramic, glass, or polyimide film. The heating element may be sandwiched between two insulating materials.

[0054] The heater assembly may include a flexible heating element disposed around or surrounding the outer surface of the heating chamber. The flexible heating element may have a length substantially equal to the length of the aerosol-forming substrate provided within the aerosol-generating article. The heating chamber may be longer than the heating element. The heating chamber may have at least one end portion that is not covered or surrounded by the heating element. The end portions may be provided at both ends of the heating chamber that are not covered or surrounded by the heating element. The end portions or a set of end portions may act as spacer portions to prevent direct contact between the heating element and other components of the heater assembly. Each end portion or a set of end portions may have a length of less than 2 millimeters, preferably less than 1 millimeter, preferably about 0.5 millimeters. Advantageously, the spacer portions may be cooler during heating than the portion of the heating chamber covered or surrounded by the heating element. The spacer portions may include funnel-shaped end portions or stepped end portions.

[0055] The heating chamber may be configured to receive at least a portion of the aerosol-generating article (as defined below).

[0056] An aerosol generator is provided according to embodiments of the present disclosure. The aerosol generator may include a heater assembly made of any of the heater assemblies described above. The aerosol generator may include a power supply or a power source for supplying power to the heater assembly.

[0057] An aerosol generator is provided according to an embodiment of the present disclosure. The aerosol generator comprises a heater assembly made of any of the heater assemblies described above, and a power supply or power source for supplying power to the heater assembly.

[0058] The power source may be any suitable power source, such as a DC voltage source. In one embodiment, the power source is a lithium-ion battery. Alternatively, the power source may be a nickel-metal hydride battery, a nickel-cadmium battery, or a lithium-based battery, such as a lithium-cobalt, lithium iron phosphate, or lithium polymer battery.

[0059] The aerosol generator is preferably a handheld aerosol generator that is comfortable for the user to hold between the fingers of one hand.

[0060] The aerosol generator may further include a control circuit configured to control the supply of power to the heater assembly. The control circuit may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), or other electronic circuit capable of providing control. The control circuit may include further electronic components. For example, in some embodiments, the control circuit may include a sensor element, a switch element, or a display element. Power may be supplied to the heater assembly continuously after the device is started, or intermittently (e.g., with each smoke extraction). Power may be supplied to the heater assembly in the form of current pulses, for example, by pulse width modulation (PWM).

[0061] The aerosol generator may include a device housing. The device housing may house a heater assembly, a power supply, and a control circuit. The housing may include an opening for receiving an aerosol generating article. The opening may be connected to an aerosol outlet of a second heater casing of the heater assembly, allowing the aerosol generating article to be inserted into the heating chamber. The housing may include an air intake. The air intake may be connected to an air intake of a first heater casing of the heater assembly.

[0062] The housing may contain any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of these materials, or thermoplastic resins suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably lightweight and not brittle.

[0063] According to embodiments of this disclosure, an aerosol generating system is provided which comprises an aerosol generating device according to any of the embodiments described above. The aerosol generating system may also comprise an aerosol generating article containing an aerosol forming substrate.

[0064] According to embodiments of this disclosure, an aerosol generating system is provided, comprising an aerosol generating device according to any of the embodiments described above, and an aerosol generating article containing an aerosol forming substrate.

[0065] As used herein, the term “aerosol-generating article” refers to an article comprising an aerosol-forming substrate that releases volatile compounds capable of forming aerosols when heated within an aerosol generator. The aerosol-generating article is separated from the aerosol generator and is also configured to be combined with the aerosol generator for heating the aerosol-generating article.

[0066] The aerosol-generating article may be substantially cylindrical in shape. The aerosol-generating article may be substantially elongated. The aerosol-forming substrate may be substantially cylindrical in shape. The aerosol-forming substrate may be substantially elongated.

[0067] The aerosol generating article may have an overall length of approximately 30 mm to approximately 100 mm. The aerosol generating article may have an outer diameter of approximately 5 mm to approximately 12 mm. The aerosol forming substrate may have a length of approximately 10 mm to approximately 18 mm. Furthermore, the diameter of the aerosol forming substrate may be approximately 5 mm to approximately 12 mm. The aerosol generating article may be equipped with a filter plug. The filter plug may be located at the downstream end of the aerosol generating article. The filter plug may be a cellulose acetate filter plug. In one embodiment, the filter plug is approximately 7 mm long, but may have a length of approximately 5 mm to approximately 12 mm.

[0068] In one embodiment, the aerosol generating article may have a total length of approximately 45 mm. The aerosol generating article may have an outer diameter of approximately 7.3 mm, or it may have an outer diameter of approximately 7.0 mm to approximately 7.4 mm. Furthermore, the aerosol forming substrate may have a length of approximately 12 mm. Alternatively, the aerosol forming substrate may have a length of approximately 16 mm. The aerosol generating article may be provided with an outer paper wrapper. Furthermore, the aerosol generating article may be provided with a separation section between the aerosol forming substrate and the filter plug. The separation section may be approximately 21 mm or approximately 26 mm, or it may be in the range of approximately 5 mm to approximately 28 mm. Separation may be provided by a hollow tube. The hollow tube may be made from cardboard or cellulose acetate.

[0069] The aerosol-forming substrate may be a solid aerosol-forming substrate. Alternatively, the aerosol-forming substrate may comprise both solid and liquid components. The aerosol-forming substrate may contain a tobacco-containing material that includes volatile tobacco-flavored compounds released from the substrate upon heating. Alternatively, the aerosol-forming substrate may contain a non-tobacco material. The aerosol-forming substrate may further comprise aerosol-forming bodies. Suitable examples of aerosol-forming bodies include glycerin and propylene glycol.

[0070] If the aerosol-forming substrate is a solid aerosol-forming substrate, it may contain one or more of the following: herb leaves, tobacco leaves, tobacco vein fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and puffed tobacco, and may be in the form of, for example, powder, granules, pellets, fragments, spaghetti, slivers, or sheets. The solid aerosol-forming substrate may be in loose form or may be provided in a suitable container or cartridge. Optionally, the solid aerosol-forming substrate may contain additional tobacco or non-tobacco volatile flavor compounds that are released upon heating of the substrate. The solid aerosol-forming substrate may also contain, for example, capsules containing additional tobacco or non-tobacco volatile flavor compounds, which may melt during heating of the solid aerosol-forming substrate.

[0071] As used herein, “homogenized tobacco” refers to a material formed by agglomerating particulate tobacco. Homogenized tobacco may be in the form of a sheet. Homogenized tobacco material may have an aerosol-forming content of more than 5% by dry weight. Alternatively, homogenized tobacco material may have an aerosol-forming content of 5% to 30% by dry weight. Homogenized tobacco material sheets may be formed by agglomerating particulate tobacco obtained by crushing or otherwise finely grinding one or both of the leaf blades and / or stems of tobacco leaves. Alternatively, or additionally, homogenized tobacco material sheets may include one or more of the following: tobacco dust, tobacco fines, and other particulate tobacco by-products formed during tobacco processing, handling, and shipping. The homogenized tobacco material sheet may contain one or more inherent binders (i.e., endogenous tobacco binders), one or more exogenous binders (i.e., exogenous tobacco binders), or a combination thereof, to help aggregate particulate tobacco. Alternatively, or additionally, the homogenized tobacco material sheet may contain other additives, including but not limited to tobacco and non-tobacco fibers, aerosol formizers, wetting agents, plasticizers, flavoring agents, fillers, aqueous and non-aqueous solvents, and combinations thereof.

[0072] In a particularly preferred embodiment, the aerosol-forming substrate comprises an aggregate of crimped sheets of homogenized tobacco material. As used herein, the term “crimped sheet” means a sheet having a plurality of substantially parallel ridges or undulations. When the aerosol-generating article is assembled, it is preferable that the substantially parallel ridges or undulations extend along or parallel to the longitudinal axis of the aerosol-generating article. This is advantageous as it facilitates the assembly of crimped sheets of homogenized tobacco material to form the aerosol-forming substrate. However, naturally, the crimped sheets of homogenized tobacco material to be included in the aerosol-generating article may, in an alternative or additional manner, have a plurality of substantially parallel ridges or undulations that are arranged at acute or obtuse angles with respect to the longitudinal axis of the aerosol-generating article when the aerosol-generating article is assembled. In a particular embodiment, the aerosol-forming substrate may comprise an aggregate of sheets of homogenized tobacco material that are substantially uniformly textured across substantially its entire surface. For example, the aerosol-forming substrate may include an aggregate of crumpled sheets of homogenized tobacco material, each containing a plurality of substantially parallel ridges or undulations substantially evenly spaced across the width of the sheet.

[0073] Optionally, the solid aerosol-forming substrate may be provided on or embedded within a thermally stable carrier. The carrier may take the form of a powder, granules, pellets, fragments, spaghetti, strips, or sheets. Alternatively, the carrier may be a tubular carrier having a thin layer of solid substrate deposited on its inner surface, its outer surface, or both its inner and outer surfaces. Such tubular carriers may be formed from, for example, paper or paper-like material, nonwoven carbon fiber mat, low-mass coarse mesh metal screen, or perforated metal foil, or any other thermally stable polymer matrix.

[0074] The solid aerosol-forming substrate may be deposited on the surface of a carrier, for example, in the form of a sheet, foam, gel, or slurry. The solid aerosol-forming substrate may be deposited over the entire surface of the carrier, or alternatively, in a pattern to provide non-uniform flavor delivery during use.

[0075] Although the above refers to a solid aerosol-forming substrate, it will be apparent to those skilled in the art that other forms of aerosol-forming substrates may be used in other embodiments. For example, the aerosol-forming substrate may be a liquid aerosol-forming substrate. If a liquid aerosol-forming substrate is provided, the aerosol generator preferably includes means for holding the liquid. For example, the liquid aerosol-forming substrate may be held in a container or liquid storage section. Alternatively, or additionally, the liquid aerosol-forming substrate may be absorbed into a porous carrier material. The porous carrier material may be made of any suitable absorbent plug or body, such as foamed metal or plastic material, polypropylene, terylene, nylon fiber, or ceramic. The liquid aerosol-forming substrate may be held in the porous carrier material before use of the aerosol generator, or, alternatively, the liquid aerosol-forming substrate material may be released into the porous carrier material during or immediately before use. For example, the liquid aerosol-forming substrate may be provided in a capsule. The capsule shell preferably melts upon heating, releasing the liquid aerosol-forming substrate into the porous carrier material. The capsules may optionally contain a solid combined with a liquid.

[0076] Alternatively, the carrier may be a nonwoven fiber or bundle of fibers in which tobacco components are incorporated. The nonwoven fiber or bundle of fibers may include, for example, carbon fibers, natural cellulose fibers, or cellulose derivative fibers.

[0077] Embodiments of this disclosure provide a method for manufacturing a heater assembly for an aerosol generator. The method may include providing a first heater casing including an air intake. The method may include providing a second heater casing including an aerosol outlet. The method may include providing a heating chamber for heating an aerosol-forming substrate. The method may include arranging the heating chamber to define an airflow path through the heater assembly by fluid communication with both the air intake and the air outlet. The method may include arranging the heating chamber between the first heater casing and the second heater casing. The method may include fastening the first and second heater casings together using fasteners. The fasteners may be configured to seal the airflow path by applying axial force to the first and second heater casings, thereby biasing the axially opposite inner surfaces of the first and second heater casings to engage in a sealing engagement with the axially opposite end faces of the respective heating chambers.

[0078] Embodiments of the present disclosure provide a method for manufacturing a heater assembly for an aerosol generator. The method includes providing a first heater casing including an air intake, a second heater casing including an aerosol outlet, providing a heating chamber for heating an aerosol-forming substrate, arranging the heating chamber to be in fluid communication with both the air intake and the air outlet to define an airflow path through the heater assembly, arranging the heating chamber between the first and second heater casings, and fastening the first and second heater casings together using fasteners, the fasteners being configured to apply axial force to the first and second heater casings, thereby biasing the opposite inner surfaces of the first and second heater casings to engage in a sealing engagement with the opposite end faces of the heating chamber in the axial direction, thereby sealing the airflow path.

[0079] The method may further include applying an axial compressive force to the first and second heater casings before attaching them to each other using fasteners. The compressive force may be between 100 and 300 Newtons, preferably about 200 Newtons.

[0080] The heating chamber may be press-fitted into a recess formed on the inner surface of the first heater casing.

[0081] The heating chamber may be press-fitted into a recess formed on the inner surface of the second heater casing.

[0082] Features described in relation to one of the above embodiments may be equally applicable to other embodiments of the present disclosure.

[0083] The present invention is defined in the claims. However, a non-exclusive list of non-limiting embodiments is provided below. One or more features of these embodiments may be combined with one or more features of other embodiments, forms, or aspects described herein. [Examples]

[0084] Example 1: A heater assembly for an aerosol generator, comprising: a first heater casing including an air intake; a second heater casing including an aerosol outlet; and a heating chamber for heating an aerosol forming substrate, the heating chamber being in fluid communication with both the air intake and the aerosol outlet to define an airflow path through the heater assembly. Example 2: A heater assembly according to Embodiment 1, wherein the heating chamber is disposed between the first heater casing and the second heater casing. Example 3: A heater assembly according to Embodiment 1 or 2, wherein a first and second heater casing are attached to each other by fasteners, the fasteners being configured to apply axial force to the first and second heater casings, thereby biasing the axially opposite inner surfaces of the first and second heater casings to engage in a sealing manner with the axially opposite end faces of the respective heating chambers, thereby sealing the airflow path. Example 4: A heater assembly according to any of Examples 1 to 3, wherein at least one of the first and second heater casings includes an internal cavity surrounding a heating chamber, and the length of the heating chamber is greater than the length of the internal cavity in the unassembled heater assembly. Example 5: A heater assembly according to Example 4, in which the length of the heating chamber is approximately 0.5 percent to approximately 8.5 percent longer than the length of the internal cavity. Example 6: A heater assembly according to Example 5, in which the length of the heating chamber is approximately 1.0 percent to approximately 5.0 percent longer than the length of the internal cavity. Example 7: A heater assembly according to Example 6, in which the length of the heating chamber is approximately 1.3 percent to approximately 3.1 percent longer than the length of the internal cavity. Example 8: A heater assembly according to any of Examples 1 to 7, wherein at least one of the first and second heater casings comprises a material having a tensile modulus of less than 6 gigapascals. Example 9: A heater assembly according to Example 8, wherein at least one of the first and second heater casings comprises a material having a tensile modulus of less than 5 gigapascals. Example 10: A heater assembly according to Example 9, wherein at least one of the first and second heater casings comprises a material having a tensile modulus of less than 4 gigapascals. Example 11: A heater assembly according to any of Examples 1 to 10, wherein at least one of the first and second heater casings contains a polymer. Example 12: A heater assembly according to any of Examples 1 to 11, wherein at least one of the first and second heater casings includes a chamfered portion disposed on the inner surface of at least one of the first and second heater casings for axially aligning the heating chamber. Example 13: A heater assembly according to any of Examples 1 to 12, wherein the fasteners include threaded fasteners. Example 14: A heater assembly according to any of Examples 1 to 12, wherein the fasteners include snap-fit ​​fasteners. Example 15: A heater assembly according to any of Examples 1 to 14, wherein the heater assembly includes multiple fasteners. Example 16: A heater assembly according to Example 15, in which multiple fasteners are symmetrically spaced around the outer circumference of the first and second heater casings. Example 17: A heater assembly according to any of Examples 1 to 16, wherein the first heater casing, the second heater casing, and the heating chamber each include an airflow channel, and the airflow channels communicate to define an airflow path. Example 18: A heater assembly according to any of Examples 1 to 17, wherein the heating chamber includes a tubular heating chamber. Example 19: A heater assembly according to Example 18, wherein the diameter of the tubular heating chamber at each end of the tubular heating chamber is greater than the diameter of the tubular heating chamber in the region between the two ends of the tubular heating chamber. Example 20: A heater assembly according to Example 18 or 19, wherein each end of the tubular heating chamber is flared or funnel-shaped. Example 21: A heater assembly according to Example 20, wherein the axial length of the flared or funnel-shaped end of the tubular heating chamber is 0.5 percent to 10 percent of the total length of the tubular heating chamber. Example 22: A heater assembly according to Example 18 or 19, wherein each end of the tubular heating chamber has a stepped or beveled profile. Example 23: A heater assembly according to Example 22, wherein the axial length of the stepped or tapered end of the tubular heating chamber is 0.5 percent to 10 percent of the total length of the tubular heating chamber. Example 24: An aerosol generator comprising a heater assembly according to any of Examples 1 to 23 and a power supply for supplying power to the heater assembly. Example 25: A method for manufacturing a heater assembly for an aerosol generator, comprising: providing a first heater casing including an air intake; providing a second heater casing including an aerosol outlet; arranging a heating chamber to heat an aerosol forming substrate and to fluidly communicate with both the air intake and the air outlet to define an airflow path through the heater assembly; arranging the heating chamber between the first heater casing and the second heater casing; and fastening the first and second heater casings together using fasteners, wherein the fasteners are configured to apply axial force to the first and second heater casings, biasing the axially opposite inner surfaces of the first and second heater casings to engage in a sealing manner with the axially opposite end faces of the respective heating chambers, thereby sealing the airflow path. Example 26: The method according to Example 25 further includes applying an axial compressive force to the first and second heater casings before attaching the first and second heater casings to each other using fasteners.

[0085] Here, we will further describe the embodiments with reference to the figures. [Brief explanation of the drawing]

[0086] [Figure 1] Figure 1 is a cross-sectional view of the heater assembly according to an embodiment of the present disclosure, showing the longitudinal axis. [Figure 2] Figure 2A is a schematic longitudinal cross-sectional view of the heater assembly shown in Figure 1 in an unassembled state, with the heating chamber located outside the heater casing. Figure 2B is a schematic longitudinal cross-sectional view of the heater assembly shown in Figure 1 just before assembly, with the heating chamber located inside the heater casing. [Figure 3A-3B] Figure 3A is a longitudinal section of a heater assembly according to another embodiment of the present disclosure. Figure 3B is an enlarged view of a portion of the heater assembly contained within the box labeled D in Figure 3A. [Figure 4A-4B] Figures 4A and 4B are side views of two exemplary heating chambers for use in the heater assembly according to this disclosure. [Figures 5A-5C] Figures 5A to 5C are schematic cross-sectional views of a known tubular heating chamber, illustrating potential problems arising from manufacturing tolerances resulting from press-fitting the heating chamber into the heater casing. [Figure 6] Figure 6 is a schematic cross-sectional view showing an aerosol generator according to an embodiment of the present disclosure and the interior of an aerosol generating article received inside the aerosol generator. [Modes for carrying out the invention]

[0087] Referring to Figure 1, Figure 1 shows a longitudinal cross-section of a heater assembly 1 comprising a first heater casing 2, a second heater casing 4, and a heating chamber 6 for heating an aerosol-forming substrate. The first heater casing 2 includes a substantially flat support section 2a and a first tubular section 2b. The support section 2a of the first heater casing 2 has an inner surface 2c facing the second heater casing 4. An air intake (not shown) is located at the distal end of the first tubular section 2b, and the first tubular section 2b extends distally away from the support section 2a in a direction parallel to the longitudinal axis XX of the heater assembly 1.

[0088] The second heater casing 4 includes a hollow shell section 4a and a second tubular section 4b. The hollow shell section 4a has an internal cavity 4c surrounding the heating chamber 6 and is open at its distal end to allow the heating chamber to be received within the internal cavity 4c. The internal cavity 4c of the hollow shell section 4a is closed at its distal end by the inner surface 2c of the support section 2a of the first heater casing 2. An aerosol outlet 10 is located at the proximal end of the second tubular section 4b, which extends proximal away from the hollow shell section 4a in a direction parallel to the longitudinal axis XX of the heater assembly 1. The aerosol outlet 10 is defined by an opening 12 configured to receive an aerosol-generating article (not shown). The aerosol exits the opening 10 via the aerosol-generating article received within the heating chamber 6.

[0089] The heating chamber 6 includes a tubular heating chamber made from a stainless steel tube. A heating element 8 is arranged around the outer surface of the heating chamber to heat the heating chamber 6, and then heats an aerosol-forming substrate (not shown) received in the internal space of the tubular heating chamber 6. The heating element includes a heat-resistant flexible polyimide film having an electrical resistance heating track (not shown) formed in a meandering pattern on the film. The resistance heating track is connected to a power source (not shown) and generates heat when current passes through the resistance heating track. The heating element is arranged around substantially the entire length of the tubular heating chamber 6 and heats substantially the entire length of the tubular heating chamber 6.

[0090] The heating chamber 6 is supported on the support section 2a of the first heater casing 2. The distal end or first end 6a of the heating chamber 6 is press-fitted into a first recess 14 formed on the inner surface 2c of the first heater casing 2. The inner peripheral edge of the recess 14 has an inclined portion or chamfered portion 16 to position the heating chamber 6 within the recess 14 and to accurately align the heating chamber 6 with respect to the longitudinal axis XX of the heater assembly 1. The proximal end or second end 6b of the heating chamber 6 is press-fitted into a second recess 18 formed on the inner surface of the internal cavity 4c of the second heater casing 4. The inner peripheral edge of the recess 18 has an inclined portion or chamfered portion 20 to position the heating chamber 6 within the recess 18 and to accurately align the heating chamber 6 with respect to the longitudinal axis XX of the heater assembly 1. The second recess 18 is located in a direction parallel to the longitudinal axis XX of the heater assembly 1 and opposite to the axial direction of the first recess 14.

[0091] The first heater casing 2 and the second heater casing 4 are attached to each other to enclose the heating chamber 6. The distal end of the second heater casing 4 has two bosses or connecting blocks 22 disposed on opposite sides of each other on the outer surface of the second heater casing 4. Each boss 22 has a hole 24 for receiving a screw 26. Two bosses or connecting blocks 28 are disposed at the proximal end of the first heater casing 2 in positions corresponding to the box 22. Each of the bosses 28 has a hole 30 for receiving a screw 26. To attach the first heater casing 2 and the second heater casing 4, the proximal end of the first heater casing 2 is engaged with the distal end of the second heater casing 4, and the screw 26 is inserted through the holes 24 and 30 to engage and hold the first heater casing 2 and the second heater casing 4 together. Thus, the screw 26 acts as a fastener that engages and holds the first heater casing 2 and the second heater casing 4 together.

[0092] The side walls of the internal cavity 4c of the second heater casing 4 are radially spaced away from the heating chamber 6, defining a hollow air space 13 around the heating chamber 6. The hollow air space 13 helps to insulate the heating chamber 6, which helps to reduce heat loss from the heating chamber 6 and also helps to reduce heat transfer to the outside of the heater assembly 1 and the aerosol generator.

[0093] The first heater casing 2 and the second heater casing 4 are made from polyether ether ketone (PEEK) due to their advantageous thermal insulation and mechanical properties. PEEK has a lower thermal conductivity than the stainless steel tubular heating chamber 6, which helps reduce heat transfer or heat loss through the first heater casing 2 and the second heater casing 4. It also helps maintain the outer surface of the heater assembly 1 at a lower temperature than the outer surface of the heating chamber 6. Furthermore, it helps retain heat within the heating chamber, improving aerosol generation.

[0094] Another advantage of PEEK is that it has a lower tensile modulus or Young's modulus than stainless steel. The tensile modulus of PEEK is typically in the range of about 3.7 gigapascals to about 3.95 gigapascals, while the tensile modulus of stainless steel is typically in the range of 190 gigapascals to 203 gigapascals, although these values ​​may vary depending on the specific composition of each material. These values ​​mean that when a force is applied to the heater assembly 1, the heating chamber is stiffer than the first heater casing 2 and the second heater casing 4, and therefore the first heater casing 2 and the second heater casing 4 will elastically deform preferentially over the heating chamber 6. Such preferential elastic deformation has been found to be very advantageous for the heater assembly of this disclosure, as will be discussed in more detail below.

[0095] The tubular heating chamber 6 is positioned between the first heater casing 2 and the second heater casing 4. The tubular heating chamber 6 is slightly longer (0.5 to 8.5 percent longer) than the length of the internal cavity 4c of the second heater casing 4 (including the depth of the second recess 16 of the second heater casing 4 and the depth of the first recess 14 of the first heater casing 2). The difference in length between the heating chamber 6 and the internal cavity 4c is not visible in the assembled heater assembly as shown in Figure 1, but the difference in length will be shown and discussed in more detail below with respect to Figures 2A and 2B. When the first heater casing 2 and the second heater casing 4 are mounted together around the heating chamber 6, the slightly longer and more rigid heating chamber 6 causes the first heater casing 2 and the second heater casing 4 to elastically deform when their respective ends engage. The first heater casing 2 and the second heater casing 4 are maintained in their elastically deformed state by a screw 26 that engages and holds the first heater casing 2 and the second heater casing 4 together. The screw 26 applies an axial force (indicated by arrow A in Figure 1) to the first heater casing 2 and the second heater casing 4 in a direction parallel to the longitudinal axis XX of the heater assembly 1. The axial force biases the inner surfaces of the first recess 14 and the second recess 16 to engage in a sealing engagement with the end faces of the first end 6a and the second end 6b of the heating chamber 6, respectively. The sealing engagement is a result of a compressive force (indicated by arrow B in Figure 1) generated at the interface between the heating chamber 6 and the first heater casing 2 and the second heater casing 4 due to the axial force applied by the screw 26. Localized plastic deformation of the first heater casing 2 and the second heater casing 4 occurs at the interface between the heating chamber 6 and the first heater casing 2 and the second heater casing 4 (i.e., in the region between arrows B in Figure 1), which helps to achieve sealing.

[0096] As described above, the screws 26 are arranged opposite each other on the respective bosses 22, 28 on the outer surfaces of the first heater casing 2 and the second heater casing 4. The symmetrical arrangement of the screws with respect to the longitudinal axis XX of the heater assembly 1 helps to apply a constant pressure between the end faces of the first heater casing 2 and the second heater casing 4 that are in contact with each other, around the entire circumference of the first heater casing 2 and the second heater casing 4. As a result of this constant pressure, a constant sealing pressure is generated between the heating chamber 6 and the first heater casing 2 and the second heater casing 4 around the entire circumference of the tubular heating chamber 6.

[0097] The tubular heating chamber 6 has an airflow channel 32 defined by the internal space of the tubular heating chamber 6, which extends axially along the length of the heating chamber 6 in a direction parallel to the longitudinal axis XX of the heater assembly 1. Furthermore, the first tubular section 2b of the first heater casing 2 has an airflow channel 34, and the second tubular section 4b of the second heater casing 4 has an airflow channel 36. The airflow channels 34, 32, and 36 of the first tubular section 2b, the tubular heating chamber 6, and the second tubular section 4b are in fluid communication with each other, respectively, defining an airflow path 38 through the heater assembly 1 between an air intake (not shown) and an aerosol outlet 10. Thus, the heating chamber 6 is in fluid communication with both the air intake and the aerosol outlet 10.

[0098] The heating chamber 6 is axially aligned with the first tubular section 2b and the second tubular section 4b of the first heater casing 2 and the second heater casing 4, respectively. Therefore, the axial force applied by the screw 26 (indicated by arrow A in Figure 1) biases the heating chamber 6 and the first and second heater casings 2 and 4 to engage in a sealing engagement with each other, sealing the airflow path 38 and reducing the possibility of aerosol leakage from the airflow path 38 at the intersection between the heating chamber 6 and the first and second heater casings 4. This sealing engagement is achieved as a result of the elastic deformation of the first and second heater casings 2 and 4 without the use of polymer seals. Thus, such an arrangement helps reduce the possibility of unwanted byproduct release.

[0099] The first heater casing 2 has a stopper or step 39 formed on the inner surface of the first tubular section 2b within its airflow channel 34. The stopper 39 engages with the distal end of an aerosol generating article (not shown) to prevent the distal end of the aerosol generating article from moving beyond the stopper 28, and is positioned to precisely locate the aerosol-forming substrate provided within the aerosol generating article within the heating chamber 6.

[0100] Figure 2A shows a schematic longitudinal cross-sectional view of the heater assembly 1 of Figure 1 in an unassembled state. For clarity, the tubular heating chamber 6 is shown outside the first heater casing 2 and the second heater casing 4. The distal end 4d of the second heater casing is in contact with the proximal end 2d of the first heater casing 2, but there is no elastic deformation of the first heater casing 2 and the second heater casing 4. The longitudinal length l of the tubular heating chamber 6 h The difference in length l d The axial length l of the internal cavity 4c c It is larger than this. In this embodiment, the length of the internal cavity 4c is l cThis includes the depths of the recesses 14 and 18 formed in the first heater casing 2 and the second heater casing 4, and is measured from the upper or proximal flat inner surface of the recess 18 of the second heater casing 4 to the lower or distal flat inner surface of the recess 14 of the first heater casing 2. The inner surfaces of the recesses 14 and 18 form the inner surfaces of the first heater casing 2 and the second heater casing 4, respectively.

[0101] Naturally, in some embodiments, the heater assembly may not use a recess to position the heating chamber 6, but may rely solely on the axial force applied by the screw 26 shown in Figure 1 to hold the heating chamber in place. In such an arrangement, the length l of the internal cavity c This is simply the length of the internal cavity 4c of the second heater casing 4, i.e., the axial length from the distal end 4d of the second heater casing to the inner surface of the upper or proximal end wall 4e of the second heater casing.

[0102] Figure 2B is a schematic longitudinal cross-sectional view of the heater assembly 1 of Figure 1 immediately before assembly. The heating chamber 6 is located inside the internal cavity 4c of the second heater casing and is axially positioned between the first heater casing 2 and the second heater casing 4. The difference in length l between the tubular heating chamber 6 and the internal cavity 4c is... d As a result, the distal end 4d of the second heater casing 4 is at a distance l d It is spaced apart only from the proximal end 2d of the first heater casing 2.

[0103] To assemble heater assembly 1, a compressive force of approximately 200 Newtons (indicated by arrow C in Figure 2B) is applied to heater assembly 1. The compressive force C biases the distal end 4d of the second heater casing to engage with the proximal end 2d of the first heater casing 2, closing the space or gap between the first heater casing 2 and the second heater casing 4. Due to the longer, more rigid heating chamber 6, the first heater casing 2 and the second heater casing 4 undergo elastic deformation as described above. Next, a screw 26 is inserted into holes 24 and 30 formed in bosses 22 and 28, and tightened with the compressive force C applied, engaging and holding the first heater casing 2 and the second heater casing 4. Then, the compressive force C is removed. After the compressive force C is removed, the screw 26 maintains the elastic deformation of the first heater casing 2 and the second heater casing 4. As a result, as described above, the screw 26 applies axial force to the first heater casing 2 and the second heater casing 4, thereby sealing and engaging them with the tubular heating chamber 6 and holding them in place.

[0104] It should be noted that Figures 2A and 2B are schematic and not to exact scale. For clarity, the figures have been simplified by omitting some details and resizing or exaggerating features.

[0105] Figure 3A is a longitudinal section of heater assembly 1 according to another embodiment of the present disclosure. The structure of heater assembly 1 in Figure 3A is identical to that of Figure 1, except that the first heater casing 2 and the second heater casing 4 are attached to each other using snap-fit ​​connectors 40 instead of the screws 26 and bosses 22, 28 arranged in Figure 1.

[0106] Similar to the screw 26 shown in Figure 1, the snap-fit ​​connector 40 supports the first heater casing 2 and the second heater casing 4 in their elastically deformed state, and holds the first heater casing 2 and the second heater casing 4 engaged with each other. The snap-fit ​​connector 40 applies an axial force to the first heater casing 2 and the second heater casing 4 in a direction parallel to the longitudinal axis XX of the heater assembly 1. The axial force resists the elastic deformation of the first heater casing 2 and the second heater casing 4, otherwise the first heater casing 2 and the second heater casing 4 would disengage. The axial force biases the inner surfaces of the first recess 14 and the second recess 16 to engage with the end faces of the first end 6a and the second end 6b of the heating chamber 6, respectively, thereby sealing the airflow path 38. The sealing engagement is a result of the compressive force (indicated by arrow B in Figure 3A) generated at the interface between the heating chamber 6 and the first heater casing 2 and the second heater casing 4 due to the axial force applied by the snap-fit ​​connector 40. Local plastic deformation of the first heater casing 2 and the second heater casing 4 occurs at the interface between the heating chamber 6 and the first heater casing 2 and the second heater casing 4 (i.e., in the region between arrow B in Figure 3A), assisting in the achievement of sealing.

[0107] Similar to the screw 26 in Figure 1, the snap-fit ​​connector 40 is positioned on opposite sides of the outer surfaces of the first heater casing 2 and the second heater casing 4. The symmetrical arrangement of the snap-fit ​​connector with respect to the longitudinal axis XX of the heater assembly 1 helps to apply a constant pressure between the end faces of the first heater casing 2 and the second heater casing 4, which are in contact with each other, around the entire circumference of the first heater casing 2 and the second heater casing 4. As a result of this constant pressure, a constant sealing pressure is generated between the heating chamber 6 and the first heater casing 2 and the second heater casing 4 around the entire circumference of the tubular heating chamber 6.

[0108] Figure 3B is an enlarged view of one of the snap-fit ​​connectors 40 of the heater assembly 1 contained within the box labeled D in Figure 3A. The snap-fit ​​connector 40 includes a cantilever 42 and a ratchet 44. The ratchet 44 is disposed at the proximal end of the cantilever 42. The cantilever 44 and ratchet 44 are integrally formed with the first heater casing 2 at the proximal edge of the first heater casing 2. The snap-fit ​​connector 40 further includes a slot 46 formed on the inner surface of the second heater casing 4 near the distal end of the second heater casing 4. The slot 46 is configured to receive the ratchet 44. The ratchet 44 has an inclined tip edge, and the cantilever 42 can elastically deform to allow the ratchet to pass through the internal cavity of the second heater casing 4 and into the slot 46. The ratchet 44 has a square rear edge that prevents the ratchet 44 from being removed from the slot 46 after it has been received in the slot 46.

[0109] As can be seen in Figure 3A, the snap-fit ​​connector 40 reduces the dimensions of the heater assembly 1 because it eliminates the need for the screw and boss arrangement shown in Figure 1. The snap-fit ​​connector also helps achieve a balanced alignment of the components of the heater assembly, as each component applies the same amount of axial force. Furthermore, the snap-fit ​​connector helps simplify manufacturing by requiring only a single press-fit action to attach the first heater casing 2 and the second heater casing 4, thereby reducing the number of parts required for installation.

[0110] Figures 4A and 4B are side views of two exemplary heating chambers for use in a heater assembly according to the present disclosure. Referring to Figure 4A, Figure 4A shows a first embodiment of heating chamber 6A. Heating chamber 6A comprises a stainless steel tube having a circular cross-section. The hollow internal space within the tubular heating chamber 6A has an internal diameter substantially corresponding to the outer diameter of an aerosol generating article (not shown) so that the tubular heating chamber 6A can receive an aerosol generating article (not shown) within the internal space. The portion 7a of heating chamber 6A at each end of heating chamber 6A is flared outward to form a funnel shape at each end of heating chamber 6A. Each flared portion 7a has a length l1, and the proportion of the total length l of heating chamber 6A formed by each length l1 of the flared portion may be in the range of 1 to 5 percent. Each flared end portion 7a of heating chamber 6A forms an angle of about 45 degrees with the longitudinal axis of heating chamber 6A. As a result of the flared end portion 7a, the outer diameter D at the two ends of the heating chamber 6A is greater than the outer diameter d of the heating chamber 6A between the two flared end portions 7a.

[0111] A portion 9a of the heating chamber 6A between the two flared end portions 7a has a straight side parallel to the longitudinal axis of the heating chamber 6A. The straight portion 9a of the heating chamber 6A has a length l2 substantially corresponding to the length of the aerosol-forming substrate provided in the aerosol-generating article configured to be received within the heating chamber 6A. Substantially all of the length l2 of the straight portion 9a of the heating chamber 6A is surrounded by a flexible heating element (not shown, but described above in relation to Figure 1). The flared portion 7a of the heating chamber 6A is not surrounded by the heating element and acts as a spacer between the end of the heating element and the components holding the heating chamber 6A, i.e., the first and second heater casings, helping to prevent direct contact between these components and the heating element.

[0112] Referring to Figure 4B, which shows a second embodiment of the heating chamber 6B, the heating chamber 6B has essentially the same structure as the heating chamber 6A in Figure 4A, except that instead of a flared end portion, the heating chamber 6B has a stepped or tapered end portion 7b. That is, the portion 7b of the heating chamber 6B at each end of the heating chamber 6B is stepped or doweled radially outward to form a step at each end of the heating chamber 6B. Each stepped portion 7b has a length l1, and the proportion of the total length l of the heating chamber 6B composed of each stepped portion length l1 may be in the range of 1 to 5 percent. As a result of the stepped end portions 7b, the outer diameter D at two ends of the heating chamber 6B is greater than the outer diameter d of the heating chamber 6B between the two stepped end portions 7b.

[0113] The portion 9b of the heating chamber 6B between the two stepped end portions 7b has a linear side parallel to the longitudinal axis of the heating chamber 6B. The linear portion 9b of the heating chamber 6B has a length l2 substantially corresponding to the length of the aerosol-forming substrate provided in an aerosol-generating article configured to be received within the heating chamber 6B. Substantially all of the length l2 of the linear portion 9b of the heating chamber 6B is surrounded by a flexible heating element (not shown, but described above in relation to Figure 1). The stepped portions 7b of the heating chamber 6B are not surrounded by the heating element and act as spacers between the ends of the heating element and the components holding the heating chamber 6B, i.e., the first and second heater casings, helping to prevent direct contact between these components and the heating element. The heating chamber 6B also includes a transition portion 11 between each of the stepped portions 7b and the linear portion 9b, providing an inclined or curved transition between the outer diameter D of each stepped portion and the outer diameter d of the linear portion.

[0114] Figures 5A–5C are schematic cross-sectional views of a known tubular heating chamber having a straight tubular wall, illustrating potential problems arising from manufacturing tolerances during press fitting that engages such a heating chamber with a heater casing. Manufacturing tolerances can result in component dimensions being larger or smaller than the specified design length, leading to connection problems for tightly fitted components. Achieving very precise manufacturing tolerances is more difficult with rapid manufacturing techniques such as injection molding.

[0115] Referring to Figure 5A, Figure 5A shows the upper part of a known or conventional tubular heating chamber 6 press-fitted into a recess 16 of the upper heater casing 4. The entire length of the tubular heating chamber 6 is linear, i.e., it has a constant outer diameter along its entire length, and the tubular heating chamber 6 does not have flared or stepped end portions like the tubular heating chambers 6A and 6B in Figures 4A and 4B. As seen in Figure 5A, the inner diameter d1 of the heating chamber 6 is smaller than the inner diameter d2 of the opening 15 of the heater casing 4 through which the aerosol-generating article passes while being inserted into the heating chamber 6. As a result, a portion of the thickness t of each wall, i.e., the end faces of the heating chamber 6, protrudes into the internal space defined by the inner diameter d2 of the opening 15. This creates a sharp step 17 in the opening 15, which may damage the aerosol-generating article when it is inserted through the opening 15, or may prevent the insertion of the aerosol-generating article. A similar situation can occur if the width w of the recessed area 16 is smaller than the thickness t of the wall of the tubular heating chamber 6. In this case, there is not enough space in the recessed area 16 to accommodate the end of the tubular heating chamber 6, and as a result, the end protrudes into the internal space defined by the inner diameter d2 of the opening 15.

[0116] Naturally, a situation similar to that shown in Figure 5A can occur at the lower or upstream end of the tubular heating chamber 6. The sharp step at the upstream end of the heating chamber may be plagued by the problem of debris or deposits accumulating in the gap formed by the step, which may be difficult to remove or clean with cleaning tools.

[0117] Figure 5B shows the lower part of a known or conventional tubular heating chamber 6 press-fitted into a recess 14 of the lower heater casing 2. As shown in Figure 5A, the entire length of the tubular heating chamber 6 is straight. The inner diameter d3 of the heating chamber 6 is larger than the inner diameter d4 of the opening 19 formed in the lower heater casing 2, so that when the aerosol generating article is properly positioned inside the heating chamber 6, a portion of the aerosol generating article protrudes through it. As a result of the formation of a sharp step 21 in the opening 19, the aerosol generating article may be damaged when passing through the opening 19, or it may be prevented from being fully inserted.

[0118] Naturally, a situation similar to that shown in Figure 5B can occur at the upper or downstream end of the tubular heating chamber 6. The sharp step at the downstream end of the heating chamber may be plagued by the problem of debris or deposits accumulating in the gap formed by the step, which may be difficult to remove or clean using cleaning tools.

[0119] Figure 5C shows the upper part of a known or conventional tubular heating chamber 6, which is press-fitted into a recess 16 of the upper heater casing 4. As shown in Figures 5A and 5C, the entire length of the tubular heating chamber 6 is linear. The outer diameter d5 of the tubular heating chamber 6 is smaller than the inner diameter of the opening 15 of the heater casing 4 through which the aerosol-generating article passes while being inserted into the heating chamber 6. As a result, press-fitting is impossible in this situation because the tubular heating chamber 6 simply passes through the opening 15.

[0120] Figure 5D is a schematic cross-sectional view of the top of the tubular heating chamber 6A shown in Figure 4A. As described above, the tubular heating chamber 6A has walls with funnel-shaped or flared end portions 7a. The flared end portions 7a are press-fitted into recesses 16 of the second heater casing 4. The outer diameter D of the flared end portions 7a is larger than the outer diameter d of the portion of the tubular heating chamber 6A between the two flared end portions 7a (only one flared end portion is visible in Figure 5D). The outer diameter D of the flared end portions 7a is also larger than the inner diameter d7 of the opening 15 of the heater casing 4 through which the aerosol-generating article passes when it is inserted into the heating chamber 6. The outer diameter D of the flared end portions 7a is larger than the inner diameter d7 of the opening 15, even when considering radial or transverse manufacturing tolerances of the inner diameter d7.

[0121] The configuration in Figure 5D significantly reduces the possibility that a portion of the end face 6c of the wall of the tubular heating chamber 6A protrudes into the airflow path cross-section defined by diameter d7 in Figure 5D. Furthermore, the end face 6c of the wall of the tubular heating chamber 6A is angled away from the cross-section of the airflow path defined by diameter d7, further reducing the possibility that a portion of the end face 6c of the wall of the tubular heating chamber 6A protrudes into the airflow path. The configuration in Figure 5D, and in particular the use of a tubular heating chamber 6A having a flared or funnel-shaped end portion 7a, is suitable for rapid manufacturing techniques as it allows for the use of components with larger radial or lateral tolerances. The configuration in Figure 5D also significantly reduces the risk of damage to the aerosol-generating article when it is inserted into the heating chamber 6A.

[0122] It will be understood that the tubular heating chamber 6B in Figure 4B can also be used in place of heating chamber 6A in the configuration of Figure 5D to achieve the same benefits. The large outer diameter D of the stepped end portion 7b of heating chamber 6B reduces the possibility that any part of the end face of the wall of the tubular heating chamber 6B will protrude into the diameter d7 and airflow path in Figure 5D. Heating chamber 6B also allows the use of components with larger radial or lateral tolerances, reducing the risk of damage to the aerosol-generating article when inserting it into heating chamber 6B.

[0123] It should be noted that Figures 5A–5D are schematic and not to exact scale. For clarity, the figures have been simplified by omitting some details and altering or exaggerating the size of features.

[0124] Figure 6 is a schematic cross-sectional view showing the interior of the aerosol generator 100 and the aerosol generating article 200 received inside the aerosol generator 100. Together, the aerosol generator 100 and the aerosol generating article 200 form an aerosol generating system. In Figure 6, the aerosol generator 100 is shown in a simplified form. Specifically, the elements of the aerosol generator 100 are not drawn to actual size. Furthermore, elements not relevant to understanding the aerosol generator 100 have been omitted.

[0125] The aerosol generator 100 comprises a housing 102 capable of housing either the heater assembly 1 shown in Figure 1 or 3A, a power supply 103, and a control circuit 105. In Figure 6, a first heater casing 2, a heating chamber 6, and a second heater casing 4 are shown. As described above in relation to Figure 1, the heating chamber 6 has a flexible heating element (not shown) arranged around it to heat the heating chamber 6. The power supply 103 is a battery, which in this embodiment is a rechargeable lithium-ion battery. The control circuit 105 is connected to both the power supply 103 and the heating element and controls the supply of electrical energy from the power supply 103 to the heating element to regulate the temperature of the heating element.

[0126] The housing 102 includes an opening 104 at the proximal or mouth end of the aerosol generator 100 through which the aerosol generating article 200 is received. The opening 104 is connected to an opening 12 in the heater assembly 1 in Figure 1 through which the aerosol exits the heater assembly 1. However, naturally, the majority of the aerosol exits the aerosol generator 100 via the heater assembly 1 and the aerosol generating article 200. The housing 102 further includes an air intake 106 at the distal end of the aerosol generator 100. The air intake 106 is connected to an air intake located at the distal end of the first tubular section 2b of the first heater casing 2. The first tubular section 2b delivers air from the air intake 106 to the heating chamber 6.

[0127] The aerosol generating article 200 comprises an end plug 202, an aerosol forming substrate 204, a hollow tube 206, and a mouthpiece filter 208. Each of the above-mentioned components of the aerosol generating article 100 is substantially cylindrical, and each has substantially the same diameter. The components are arranged coaxially, in contact with each other, and continuously, and are surrounded by an outer paper wrapper 210 to form a cylindrical rod. The aerosol forming substrate 204 is a tobacco rod or plug comprising an assembly of crumpled sheets of homogenized tobacco material surrounded by a wrapper (not shown). The crumpled sheets of homogenized tobacco material contain glycerin as an aerosol former. The end plug 202 and the mouthpiece filter 208 are formed from cellulose acetate fibers.

[0128] The distal end of the aerosol generating article 200 is inserted into the aerosol generator 100 through the opening 104 of the housing 102 and pushed into the aerosol generator 100 until it engages with a stopper (not shown in Figure 6) located in the second heater casing 4, to which the aerosol generating article 200 is fully inserted. The stopper helps to position the aerosol forming substrate 204 precisely within the heating chamber 6 so that the heating chamber 6 can heat the aerosol forming substrate 204 to form an aerosol.

[0129] The aerosol generator 100 may further include a sensor (not shown) for detecting the presence of an aerosol generating article 200, a user interface (not shown) such as a button for activating a heating element, and a display or indicator (not shown) for presenting information to the user, such as remaining battery power, heating status, and error messages.

[0130] During use, the user inserts the aerosol generating article 200 into the aerosol generator 100 as shown in Figure 6. The user then starts the heating cycle by activating the aerosol generator 100, for example by pressing a switch to turn on the device. In response, the control circuit 105 controls the supply of power from the power supply 103 to a heating element (not shown) to heat the heating element, which then heats the heating chamber 6. During the heating cycle, the heating element heats the heating chamber 6 to a predetermined temperature, or a predetermined temperature range according to a temperature profile. The heating cycle may last for about 6 minutes. The heat from the heating chamber 6 is transferred to the aerosol forming substrate 204, thereby releasing volatile compounds from the aerosol forming substrate 204. The volatile compounds form an aerosol in the aerosolizing chamber formed by the hollow tube 206. During the heating cycle, the user places the mouthpiece filter 208 of the aerosol generating article 200 between their lips and inhales or breathes the mouthpiece filter 208. The generated aerosol is drawn out through the mouthpiece filter 102 and enters the user's mouth.

[0131] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers representing amounts, quantities, percentages, etc., should be understood in all cases as being modified by the term “approximately.” Furthermore, all ranges include the disclosed maximum and minimum points and any intermediate ranges therewith, which may or may not be specifically listed herein. Thus, in this context, the number A is understood as A ± 5 percent (5%). In this context, the number A may be considered to include a number that falls within the general standard error of the measurement of the characteristic modified by the number A. In some cases, such as those used in the appended claims, the number A may deviate by the percentages listed above, provided that the amount by which A deviates does not substantially affect the basic and novel characteristics of the claimed invention. Furthermore, all ranges include the disclosed maximum and minimum points and any intermediate ranges therewith, which may or may not be specifically listed herein.

Claims

1. A heater assembly for an aerosol generator, wherein the heater assembly is A first heater casing including an air intake, A second heater casing including an aerosol outlet, A heating chamber for heating an aerosol-forming substrate, comprising: a heating chamber that is in fluid communication with both the air intake and the aerosol outlet, defining an airflow path through the heater assembly; The heating chamber is disposed between the first heater casing and the second heater casing. A heater assembly in which the first and second heater casings are attached to each other by fasteners, and the fasteners are configured to apply axial force to the first and second heater casings, biasing the axially opposite inner surfaces of the first and second heater casings to engage in a sealing manner with the axially opposite end faces of the respective heating chambers, thereby sealing the airflow path.

2. The heater assembly according to claim 1, wherein at least one of the first and second heater casings includes an internal cavity surrounding the heating chamber, and the length of the heating chamber is greater than the length of the internal cavity in the heater assembly when it is not assembled.

3. The heater assembly according to claim 2, wherein the length of the heating chamber is 0.5 percent to 8.5 percent longer than the internal cavity.

4. The heater assembly according to any one of claims 1 to 3, wherein the first and second heater casings are directly attached to each other by fasteners.

5. The heater assembly according to any one of claims 1 to 3, wherein the end face of the heating chamber opposite to the axial direction is directly engaged with the end faces of the first and second heater casings opposite to the axial direction, respectively.

6. The heater assembly according to any one of claims 1 to 3, wherein at least one of the first and second heater casings comprises a material having a tensile modulus of less than 6 gigapascals.

7. The heater assembly according to any one of claims 1 to 3, wherein at least one of the first and second heater casings comprises a polymer.

8. The heater assembly according to any one of claims 1 to 3, wherein at least one of the first and second heater casings includes a chamfered portion disposed on the inner surface of at least one of the first and second heater casings for axially aligning the heating chamber.

9. The heater assembly according to any one of claims 1 to 3, wherein the fastener includes a threaded fastener or a snap-fit ​​fastener.

10. The heater assembly according to any one of claims 1 to 3, wherein the first and second heater casings are attached to each other by a plurality of fasteners.

11. The heater assembly according to claim 10, wherein the plurality of fasteners are spaced symmetrically apart around the outer circumference of the first and second heater casings.

12. The heater assembly according to any one of claims 1 to 3, wherein the first heater casing, the second heater casing, and the heating chamber each include an airflow channel, and the airflow channels communicate with each other to define the airflow path.

13. The heater assembly according to any one of claims 1 to 3, wherein the heating chamber includes a tubular heating chamber.

14. The heater assembly according to claim 13, wherein the diameter of the tubular heating chamber at each end of the tubular heating chamber is greater than the diameter of the tubular heating chamber in the region between the two ends of the tubular heating chamber.

15. The heater assembly according to claim 13, wherein each end of the tubular heating chamber is flared or funnel-shaped.

16. The heater assembly according to claim 13, wherein each end of the tubular heating chamber has a stepped or beveled profile.

17. The heater assembly according to any one of claims 1 to 3, wherein the heating chamber is configured to receive at least a portion of the aerosol-generating article.

18. Aerosol generator, A heater assembly according to any one of claims 1 to 3, An aerosol generator comprising a power supply for supplying electricity to the heater assembly.

19. A method for manufacturing a heater assembly for an aerosol generator, wherein the method is To provide a first heater casing including an air intake, To provide a second heater casing including an aerosol outlet, A heating chamber is provided for heating the aerosol-forming substrate, and the heating chamber is arranged to define an airflow path through the heater assembly by being in fluid communication with both the air intake and the aerosol outlet. The heating chamber is disposed between the first heater casing and the second heater casing. A method for attaching the first and second heater casings to each other using fasteners, wherein the fasteners are configured to apply axial force to the first and second heater casings, biasing the axially opposite inner surfaces of the first and second heater casings to engage in a sealing manner with the axially opposite end faces of the respective heating chambers, thereby sealing the airflow path.

20. The method according to claim 19, further comprising applying an axial compressive force to the first and second heater casings before attaching the first and second heater casings to each other using the fasteners.

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