HEATER ASSEMBLY HAVING SEALED AIRFLOW PATH

Abstract

A heater assembly (1) for an aerosol generating device, the heater assembly (1) comprising a first heater casing (2) including an air inlet, a second heater casing (4) 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, the heater assembly (1) further comprising a heater mount (8) where the heating chamber (6) is mounted on the heater mount (8), and a seal (30) for sealing the airflow path, the seal (30) being mounted on the heater mount (8) such that the seal (30) is spaced from the heating chamber (6).

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. In particular, 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 deliver the aerosol into a user's mouth. The present invention also relates to an aerosol generating system comprising an aerosol generating device and an aerosol-forming substrate. [Background technology]

[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 in an aerosol-generating article together with other components such as a filter. The aerosol-generating article may have a rod shape for inserting the aerosol-generating article into the heating chamber of the aerosol-generating device. A heating element is typically disposed in or around the heating chamber to heat the aerosol-forming substrate after the aerosol-generating article is inserted into the heating chamber of the aerosol-generating device.

[0003] The heating chamber may be disposed within the housing of the aerosol generating device and form part of the airflow path through the aerosol generating device. To attempt to prevent the aerosol from escaping the airflow path into other parts of the aerosol generating device, which could damage the electronics of the device, it is known to provide a seal around the airflow path and between the heating chamber and the housing. The seal may be placed in direct contact with the heating chamber and is therefore typically formed from a heat-resistant polymer such as silicone or polysiloxane. However, exposure of such polymer seals to the heating temperatures of the heating chamber may result in undesirable by-products that may contaminate the aerosol. Furthermore, such heating temperatures may degrade the seal over time.

[0004] To heat the heating chamber, the aerosol generating device may include a flexible heating element disposed around the heating chamber. In order to allow direct contact between the seal and the heating chamber and reduce heating of the seal, attempts have been made to distance the seal from the heating element, for example at the downstream end of the heating chamber. However, this may require compromising the overall dimensions of the aerosol generating device, for example through the use of a long heating chamber, increasing the energy consumption of the heating chamber and reducing the efficiency of the aerosol generating device. Furthermore, increasing the length of the heating chamber may result in the heating chamber surrounding other components of the aerosol generating article, such as the filter, which may be indirectly heated via thermal conduction through the heating chamber. Undesirably, heating the filter 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 decreased. However, this may result in a portion of the aerosol-forming substrate not being covered or surrounded by the heating element, and as a result, 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 traveling a relatively short distance through the thickness of the heating chamber wall. Thus, 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 cooler than the portion surrounded by the heating element, leading to premature condensation of the aerosol in the cooler portion. This may result in less aerosol being delivered to the user.

[0006] A further disadvantage of using a polymer seal between the heating chamber and the housing of the device is that the polymer seal provides a thermal conduction path for heat to be transferred away from the heating chamber to the material surrounding the heating chamber. This heat loss reduces the heat available to heat the aerosol-forming substrate and reduces the efficiency of the aerosol generating device.

[0007] An additional problem encountered in sealing the airflow paths in aerosol generating devices is manufacturing tolerances. Variations in component dimensions due to manufacturing tolerances can result in poor engagement between components and potential gaps through which the aerosol can leak. Achieving a good sealing engagement between components typically requires tight manufacturing tolerances that can be difficult to achieve with rapid manufacturing processes such as injection molding.

[0008] It would be desirable to provide a heater assembly for an aerosol generating device that has improved sealing of its airflow path.It would be desirable to provide a heater assembly for an aerosol generating device that is more energy efficient and improves delivery of the aerosol to a user.It would be desirable to provide a heater assembly for an aerosol generating device that can better accommodate manufacturing tolerances. Summary of the Invention

[0009] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generating device. The heater assembly may comprise a first heater casing. The first heater casing may include an air inlet. 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 inlet. The heating chamber may be in fluid communication with the aerosol outlet. The heating chamber may be in fluid communication with both the air inlet and the aerosol outlet to define an airflow path through the heater assembly. The heater assembly may comprise a heater mount. The heating chamber may be mounted on the heater mount. The heater assembly may comprise a seal for sealing the airflow path. The seal may be mounted on the heater mount. The seal may be spaced from the heating chamber.

[0010] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generating device. The heater assembly comprises a first heater casing including an air inlet, 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 inlet and the aerosol outlet to define an airflow path through the heater assembly. The heater assembly further comprises a heater mount. The heating chamber is mounted on the heater mount. The heater assembly further comprises a seal for sealing the airflow path. The seal is mounted on the heater mount such that it is spaced apart from the heating chamber.

[0011] The advantage of mounting the seal on the heater mount rather than the heated chamber is that contact between the seal and the heated chamber is avoided. Furthermore, the seal is advantageously mounted on the heater mount so as to be spaced or distanced from the heated chamber. The distance between the heated chamber and the seal means that the seal is kept cooler than the heated chamber and does not overheat. Improved sealing of the airflow path through the heater assembly can be achieved because the seal is not subjected to high thermal stresses.

[0012] An additional advantage of mounting the seal on the heater mount rather than on the heating chamber is that no space is required at the ends 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 significantly reduced. This means that a shorter heating chamber can be used and a larger percentage of the length of the heating tube can be heated. This allows for more efficient heating of the aerosol-forming substrate.

[0013] As discussed in more detail below, the heater assemblies of the present disclosure are also less susceptible to manufacturing tolerances since the seals are able to absorb at least a portion of the manufacturing tolerances to achieve an improved seal.

[0014] The aerosol outlet may be an opening for receiving an aerosol-generating article. The aerosol may exit the opening through the aerosol-generating article received within the heating chamber.

[0015] The first and second heater casings may be attached to one another. The first and second heater casings may enclose the heating chamber and the heater mount. A seal may be disposed between the heater mount and an interior surface of one of the first and second heater casings. This arrangement provides a seal between the heater mount and one of the first and second heater casings to effectively seal at least a portion of an airflow path through the heater assembly to prevent aerosol from escaping the airflow path and entering the aerosol generating device.

[0016] The first and second heater casings may be attached to one another by a fastener. The first and second heater casings may be attached to one another by a plurality of fasteners. The plurality of fasteners may be symmetrically spaced around the first and second heater casings. The fastener or plurality of fasteners may include threaded fasteners, such as screws. The fastener or plurality of fasteners may include snap-fit ​​fasteners.

[0017] The first and second heater casings may be radially spaced from the heating chamber and the heater mount to define a hollow air space around the heating chamber and the heater mount. 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 to the exterior of the heater assembly.

[0018] Optionally, a seal may be disposed between the heater mount and the inner surface of the first heater casing. Alternatively, a seal may be disposed between the heater mount and the inner surface of the second heater casing.

[0019] The seal may be attached to a first side of the heater mount. The heating chamber may be attached to a second side of the heater mount. The second side may be axially opposite the first side. The seal may be attached to a first end of the heater mount. The heating chamber may be attached to a second end of the heater mount. The second end may be axially opposite the first end. An advantage of attaching the seal to a side or end of the heater mount axially opposite the first side or end is that the seal applies an axial force to the heater mount, which in turn applies an axial force to the heating chamber. The application of the axial force causes the heating chamber and the heater mount to engage with each other, sealing the airflow path at the intersection between the heater mount and the heating chamber. Additionally, the axial force is transferred along the length of the airflow path, for example, to the points where the heater mount and the heating chamber are connected to the inner surfaces of the first and second heater casings. Thus, the seal provides a seal at these connection points to also seal along the length of the airflow path, helping to prevent aerosol from escaping the airflow path and entering the aerosol generating device.

[0020] An additional advantage of attaching a seal to the side of the heater mount axially opposite the first side is that the seal can help to accommodate manufacturing tolerances. For example, the seal can help to accommodate axial or lengthwise tolerances. As used herein, the term "axial tolerance" or "lengthwise tolerance" is used to describe manufacturing tolerances in a direction substantially parallel to the major longitudinal axis or length of the heater assembly or aerosol generating device, e.g., tolerances that result in components being longer or shorter than their specified design length. Axial or lengthwise tolerances are sometimes referred to as "vertical tolerances." In addition, the seal can also help to accommodate tilt tolerances. As used herein, the term "tilt tolerance" is used to describe manufacturing tolerances that cause components to tilt relative to the major longitudinal axis or length of the heater assembly or aerosol generating device, e.g., when one side of the support is at a different level or axial position relative to the other side of the support, causing the component it supports to tilt.

[0021] The seal helps accommodate manufacturing tolerances in a variety of ways. For example, if a component such as a heating chamber is too short, the thickness of the seal may compensate for the lack of length of the heating chamber to allow the heater mount to engage the heating chamber and close any gaps that might otherwise result. If a component such as a heating chamber is too long, the seal may be compressed to accommodate the excess length. If a point on the surface of the heater mount onto which the heating chamber is mounted is at a different level or axial location relative to another point on the same surface such that the heating chamber is tilted when mounted, at least a portion of the seal may be compressed to allow the heating chamber to be properly aligned.

[0022] The heater mount may be disposed upstream or distal to the heating chamber. The terms "distal", "upstream", "proximal" and "downstream" are used to describe the relative locations of components or portions of components of the aerosol generating apparatus and aerosol generating articles. The aerosol generating articles and devices according to the present disclosure have a proximal end where the aerosol exits through the aerosol generating article or device for delivery to a user during use, and an opposite distal end. The proximal end of the aerosol generating article and device may also be referred to as the oral end. During use, a user sucks on 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 are relative to the direction of travel of the aerosol through the aerosol generating article or aerosol generating apparatus when a user sucks on 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 referred to as the downstream end of the aerosol-generating article, and the distal end of the aerosol-generating article may also be referred to as the upstream end of the aerosol-generating article.

[0023] Advantageously, by locating the heater mount upstream or distal to the heating chamber, the amount of heated aerosol that moves from the heating chamber to the heater mount is reduced because the aerosol tends to move in the direction of the airflow path through the heater assembly, i.e., from the heating chamber to the aerosol outlet that is located downstream of the heating chamber. This arrangement therefore reduces heat transfer to the heater mount and helps to keep the seal cooler than the heating chamber.

[0024] The heater mount may include a polymer, which generally has a lower thermal conductivity value compared to the material from which the heated chamber is formed, which is typically a metal or metal alloy. A heater mount including or formed from a polymer reduces heat transfer to the seal, helping to keep the seal cooler than the heated chamber.

[0025] The seal may be disposed at least 2 millimeters from the heating chamber. The seal may be disposed at least 4 millimeters from the heating chamber. The seal may be disposed about 6 millimeters from the heating chamber. The seal may be disposed 2 to 6 millimeters from the heating chamber, preferably 4 to 6 millimeters from the heating chamber.

[0026] The seal may be elastic. The seal may be formed from any suitable material. The seal may include an elastic material. The seal may include a polymer. The seal may include an elastic polymer. The seal may include or be formed from any suitable polymer, including, but not limited to, ethylene propylene diene monomer (EPDM) rubber or silicone.

[0027] The seal may be compressed when the heater assembly is assembled.The seal may be compressed between the heater mount and the first heater casing when the heater assembly is assembled.

[0028] The seal may have a Shore hardness of 30A to 90A, preferably a Shore hardness of 50A to 80A, and more preferably a Shore hardness of about 70A. These values ​​of Shore hardness have been found to be soft enough to accommodate length and tilt tolerances, yet hard enough to provide sufficient force to the heater assembly for sealing the airflow path and heater assembly integrity.

[0029] The seal may include any suitable shape. The seal may include a shape that matches the shape of the heater mount. The seal may include a shape that matches the shape of one of the first or second heater casings. The seal may include an O-ring. The seal may have any suitable cross-sectional shape in the longitudinal plane of the heater assembly, including, but not limited to, a circular cross-sectional shape, or a cross-sectional shape having two opposing flat surfaces, such as a square or rectangular cross-sectional shape.

[0030] The seal may have an uncompressed thickness or diameter of 0.5 millimeters to 2 millimeters. The seal may have an uncompressed thickness or diameter of about 1 millimeter. These uncompressed thicknesses have been found to be particularly effective in accommodating length and tilt tolerances and providing sealing of the airflow path and integrity of the heater assembly.

[0031] The first heater casing may have an airflow channel. The airflow channel of the first heater casing may be in fluid communication with the air inlet. The second heater casing may have an airflow channel. The airflow channel of the second heater casing may be in fluid communication with the aerosol outlet. The heating chamber may have an airflow channel. The airflow channel of the heating chamber may pass through a length of the heating chamber. The heater mount may have an airflow channel. The airflow channel of the heater mount may pass through a thickness or length of the heater mount. The airflow channels of each of the first heating casing, the second heater casing, the heating chamber, and the heater mount may be in fluid communication with each other to define an airflow path through the heater assembly.

[0032] The heating chamber may include a tubular heating chamber. A diameter of the tubular heating chamber at a first end of the tubular heating chamber may be greater than a diameter along the length of the tubular heating chamber. A diameter of the tubular heating chamber at a second end of the tubular heating chamber may be greater than a diameter along the length of the tubular heating chamber. A diameter of the tubular heating chamber at each end of the tubular heating chamber may be greater than a diameter in a region between the two ends of the tubular heating chamber.

[0033] Advantageously, having a diameter at one or both ends of the tubular heating chamber larger than the diameter of the tubular heating chamber along the length of the heating chamber, for example in the region between the two ends of the tubular heating chamber, allows for greater manufacturing tolerances of the heating chamber and of other components of the heater assembly. In particular, greater radial or lateral tolerances are allowed. As used herein, the terms "radial tolerance" or "lateral tolerance" are used to describe manufacturing tolerances in a direction substantially perpendicular to the major longitudinal axis or length of the heater assembly or aerosol generating device, for example, tolerances that result in components that are wider or narrower than their specified design width, or have a larger or smaller diameter than their specified design diameter. Radial or lateral tolerances are sometimes referred to as "horizontal tolerances".

[0034] Advantageously, by making the diameter of the ends of the tubular heating chamber larger than the rest of the tubular heating chamber, the inside diameter at one or both ends of the tubular heating chamber is larger than the inside diameter of the airflow path in the other component of the heater assembly with which the tubular heating chamber engages, such as the second heater casing or heater mount. This helps to avoid the end faces of the tubular heating chamber protruding or encroaching into the interior space of the airflow path, which could damage the aerosol-generating article when it is received in the heating chamber via the airflow path, and the end faces of the tubular heating chamber being smaller to provide a sealing engagement with the other component. This arrangement also allows for larger radial or lateral tolerances in the other components, as described in more detail below.

[0035] 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 percent to 20 percent larger, 1 percent to 15 percent larger, 1 percent to 12 percent larger, or 1 percent 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.

[0036] 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. A portion of the tubular heating chamber between the two ends of the tubular heating chamber 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.

[0037] 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 such 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.

[0038] At least one end of the tubular heating chamber may be flared or funnel shaped. A portion of the tubular heating chamber at both ends of the tubular heating chamber may be flared or funnel shaped. The axial length of the flared or funnel shaped end of the tubular heating chamber may be between 0.5 percent and 10 percent of the total length of the tubular heating chamber, preferably between 1 percent and 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.

[0039] The axial length of the flared or funnel-shaped end of the tubular heating chamber may be between 0.2 mm and 2 mm, preferably between 0.4 mm and 1 mm, more preferably about 0.5 mm. The flared or funnel-shaped end or ends of the tubular heating chamber may be disposed at an angle of 30 degrees to 60 degrees, 40 degrees to 50 degrees, or about 45 degrees relative to the longitudinal axis of the heating chamber or heater assembly. In some preferred embodiments, the flared or funnel-shaped end or ends of the tubular heating chamber may be disposed at an angle of less than 50 degrees, preferably less than 40 degrees, or more preferably less than 30 degrees relative to the longitudinal axis of the heating chamber or heater assembly. Advantageously, providing the flared or funnel-shaped end or ends of the tubular heating chamber at an angle of less than 30 degrees relative to the longitudinal axis of the heating chamber or heater assembly may provide optimal stiffness to the flared or funnel-shaped end or ends of the tubular heating chamber in the direction of the longitudinal axis of the heating chamber or heater assembly.

[0040] At least one end or ends of the tubular heating chamber may have a stepped profile or may be crimped. A portion of the tubular heating chamber at both ends of the tubular heating chamber may have a stepped profile or may be crimped. The axial length of the stepped or crimped ends 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, more preferably about 3.7 percent of the total length of the tubular heating chamber. A radius is preferably provided between the stepped or crimped portions to avoid sharp edges and stress concentrations.

[0041] The axial length of the flared or funnel-shaped end of the tubular heating chamber may be between 0.2 mm and 2 mm, preferably between 0.4 mm and 1 mm, more preferably about 0.5 mm.

[0042] The tubular heating chamber may have a tubular wall thickness of between 0.05 millimeters and 1.00 millimeters, preferably between 0.05 millimeters and 0.50 millimeters, and more preferably about 0.10 millimeters.

[0043] The heating chamber may be made from any suitable material, including but not limited to ceramic or metal or metal alloy. An example of a suitable material is stainless steel.

[0044] The heater assembly may comprise at least one electric heating element for heating the aerosol-forming substrate. The heater assembly may comprise multiple electric heating elements. The electric heating element or elements may be disposed about or surround the outer surface of the heating chamber. The electric heating element or elements may be disposed about or surround the inner surface of the heating chamber. The electric heating element or elements may be part of or integral with the heating chamber.

[0045] The electric heating element or 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 disilicide, etc.), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may include doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable metal alloys include stainless steels, 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-based alloys. In composite materials, the electrically resistive material may be embedded in, encapsulated in, or coated with an insulating material, or vice versa, depending on the required energy transfer kinetics and external physicochemical properties.

[0046] One or more heating elements may be formed using a metal or metal alloy that has a well-defined relationship between temperature and resistivity. Heating elements formed in this manner may be used to both heat the heating element and to monitor the temperature of the heating element during operation.

[0047] The heating element may be disposed in or on a rigid carrier material or substrate. The heating element may be disposed 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 or glass or polyimide film. The heating element may be sandwiched between two insulating materials.

[0048] The heater assembly may comprise 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 in the aerosol-generating article. The heating chamber may be longer than the heating element. The heating chamber may have at least one end that is not covered or surrounded by the heating element. Ends may be provided at both ends of the heating chamber that are not covered or surrounded by the heating element. The end or ends may act as spacer portions to prevent direct contact between the heating element and other components of the heater assembly. The end or ends may each have a length of less than 2 millimeters, preferably less than 1 millimeter, preferably about 0.5 millimeters. Advantageously, the spacer portion may be at a lower temperature during heating than the portion of the heating chamber that is covered or surrounded by the heating element. The spacer portion may include a funnel-shaped end or a stepped end.

[0049] The heating chamber may be configured to receive at least a portion of the aerosol-generating article (as defined below).

[0050] According to an embodiment of the present disclosure, there is provided an aerosol generating device, which may comprise a heater assembly according to any of the heater assemblies described above, and which may comprise a power source or sources of electricity for providing power to the heater assembly.

[0051] According to an embodiment of the present disclosure, there is provided an aerosol generating device comprising a heater assembly according to any of the heater assemblies described above, and a power source or source for supplying power to the heater assembly.

[0052] The power source may be any suitable power source, such as, for example, 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.

[0053] The aerosol generating device is preferably a handheld aerosol generating device that is comfortable for a user to hold between the fingers of one hand.

[0054] The aerosol generating device may further comprise a control circuit configured to control the supply of power to the heater assembly. The control circuit may comprise a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, or an application specific integrated chip (ASIC) or other electronic circuit capable of providing control. The control circuit may comprise further electronic components. For example, in some embodiments, the control circuit may comprise any of a sensor element, a switch element, and a display element. Power may be continuously supplied to the heater assembly after activation of the device, or may be supplied intermittently (such as every puff). Power may be supplied to the heater assembly in the form of current pulses, for example by pulse width modulation (PWM).

[0055] The aerosol generating device may include a device housing. The device housing may house the heater assembly, a power source, and a control circuit. The housing may include an opening for receiving the aerosol-generating article. The opening may be connected to an aerosol outlet of a second heater casing of the heater assembly to allow the aerosol-generating article to be inserted into the heating chamber. The housing may include an air inlet. The air inlet may be connected to an air inlet of a first heater casing of the heater assembly.

[0056] The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composites containing one or more of these materials, or thermoplastics suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably lightweight and not brittle.

[0057] According to an embodiment of the present disclosure, there is provided an aerosol generation system comprising an aerosol generating device according to any of the above-described embodiments. The aerosol generation system may also comprise an aerosol-generating article including an aerosol-forming substrate.

[0058] According to an embodiment of the present disclosure, there is provided an aerosol-generating system comprising an aerosol-generating device according to any of the above-described embodiments and an aerosol-generating article including an aerosol-forming substrate.

[0059] As used herein, the term "aerosol-generating article" refers to an article that includes an aerosol-forming substrate that releases a volatile compound capable of forming an aerosol when heated in an aerosol-generating device. The aerosol-generating article is separate from the aerosol-generating device and is configured to be combined with the aerosol-generating device to heat the aerosol-generating article.

[0060] 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.

[0061] The aerosol-generating article may have an overall length of about 30 mm to about 100 mm. The aerosol-generating article may have an outer diameter of about 5 mm to about 12 mm. The aerosol-forming substrate may have a length of about 10 mm to about 18 mm. Further, the diameter of the aerosol-forming substrate may be about 5 mm to about 12 mm. The aerosol-generating article may comprise 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 about 7 mm long, but may have a length of about 5 mm to about 12 mm.

[0062] In one embodiment, the aerosol-generating article may have an overall length of approximately 45 mm. The aerosol-generating article may have an outer diameter of approximately 7.3 mm, but 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 comprise an outer paper wrapper. Furthermore, the aerosol-generating article may comprise a separation between the aerosol-forming substrate and the filter plug. The separation may be approximately 21 mm or approximately 26 mm, but may be in the range of approximately 5 mm to approximately 28 mm. The separation may be provided by a hollow tube. The hollow tube may be made of cardboard or cellulose acetate.

[0063] 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 comprise a tobacco-containing material that contains volatile tobacco flavour compounds that are released from the substrate upon heating. Alternatively, the aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may further comprise an aerosol former. Examples of suitable aerosol formers are glycerin and propylene glycol.

[0064] When the aerosol-forming substrate is a solid aerosol-forming substrate, the solid aerosol-forming substrate may comprise, for example, one or more of powder, granules, pellets, pieces, spaghetti, strips, or sheets containing one or more of herb leaves, tobacco leaves, tobacco vein fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and expanded tobacco. 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 capsules, for example containing additional tobacco or non-tobacco volatile flavor compounds, which may melt during heating of the solid aerosol-forming substrate.

[0065] As used herein, "homogenized tobacco" refers to a material formed by agglomerating particulate tobacco. The homogenized tobacco may be in the form of a sheet. The homogenized tobacco material may have an aerosol former content of greater than 5% on a dry weight basis. Alternatively, the homogenized tobacco material may have an aerosol former content of between 5% and 30% by weight on a dry weight basis. The homogenized tobacco material sheet may be formed by agglomerating particulate tobacco obtained by grinding or otherwise comminuted one or both of the tobacco blades and the tobacco stems. Alternatively, or additionally, the homogenized tobacco material sheet may include one or more of tobacco dust, tobacco fines, and other particulate tobacco by-products formed, for example, during tobacco processing, handling, and shipping. The homogenized tobacco material sheet may include one or more inherent binders (i.e., tobacco intrinsic binders), one or more extrinsic binders (i.e., tobacco extrinsic binders), or combinations thereof to aid in the cohesion of the particulate tobacco, although alternatively or additionally, the homogenized tobacco material sheet may include other additives including, but not limited to, tobacco and non-tobacco fibers, aerosol formers, humectants, plasticizers, flavorants, fillers, aqueous and non-aqueous solvents, and combinations thereof.

[0066] In a particularly preferred embodiment, the aerosol-forming substrate comprises an assembly of crimped sheets of homogenized tobacco material. As used herein, the term "crimped sheet" refers to a sheet having a plurality of substantially parallel ridges or corrugations. When the aerosol-generating article is assembled, the substantially parallel ridges or corrugations preferably run along or parallel to the longitudinal axis of the aerosol-generating article. This advantageously facilitates assembling the crimped sheets of homogenized tobacco material to form the aerosol-forming substrate. However, it will be appreciated that a crimped sheet of homogenized tobacco material for inclusion in an aerosol-generating article may alternatively or additionally have a plurality of substantially parallel ridges or corrugations that are disposed at an acute or obtuse angle relative to the longitudinal axis of the aerosol-generating article when the aerosol-generating article is assembled. In certain embodiments, the aerosol-forming substrate may comprise an assembly of sheets of homogenized tobacco material that are substantially evenly textured across substantially its entire surface. For example, the aerosol-forming substrate may comprise an assemblage of a crimped sheet of homogenized tobacco material that includes a plurality of substantially parallel ridges or corrugations that are substantially evenly spaced across the width of the sheet.

[0067] Optionally, the solid aerosol-forming substrate may be provided on or embedded in a thermally stable carrier. The carrier may take the form of a powder, granules, pellets, pieces, spaghetti, strips, or sheets. Alternatively, the carrier may be a tubular carrier having a thin layer of solid substrate deposited on its inner surface, or on its outer surface, or on both its inner and outer surfaces. Such a tubular carrier may be formed, for example, of paper or paper-like material, non-woven carbon fiber mat, low-mass open mesh metal screen, or perforated metal foil, or any other thermally stable polymeric matrix.

[0068] The solid aerosol-forming substrate may be deposited on the surface of the carrier in the form of, for example, 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 a non-uniform flavour delivery during use.

[0069] Although reference has been made above to solid aerosol-forming substrates, it will be clear to the skilled person 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. When a liquid aerosol-forming substrate is provided, the aerosol-generating device preferably comprises a means for holding the liquid. For example, the liquid aerosol-forming substrate may be held in a container or liquid storage portion. 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, for example foamed metal or plastic materials, polypropylene, terylene, nylon fibers, or ceramics. The liquid aerosol-forming substrate may be held in the porous carrier material before use of the aerosol-generating device, 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 shell of the capsule preferably melts upon heating and releases the liquid aerosol-forming substrate into the porous carrier material. Capsules may optionally contain a solid in combination with a liquid.

[0070] Alternatively, the carrier may be a nonwoven fiber or fiber bundle having tobacco components incorporated therein. The nonwoven fiber or fiber bundle may comprise, for example, carbon fiber, natural cellulose fiber, or cellulose derivative fiber.

[0071] According to an embodiment of the present disclosure, a method of manufacturing a heater assembly for an aerosol generating device is provided. The method may include providing a first heater casing including an air inlet. 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 disposing the heating chamber in fluid communication with both the air inlet and the air outlet to define an airflow path through the heater assembly. The method may include providing a heater mount and mounting the heating chamber on the heater mount. The method may include providing a seal for sealing the airflow path. The method may include mounting the seal on the heater mount. The method may include spacing the seal from the heating chamber. The method may include mounting the first and second heater casings together to enclose the heating chamber and the heater mount.

[0072] According to an embodiment of the present disclosure, there is provided a method of manufacturing a heater assembly for an aerosol generating device, the method including: providing a first heater casing including an air inlet; providing a second heater casing including an aerosol outlet; providing a heating chamber for heating an aerosol-forming substrate, and disposing the heating chamber in fluid communication with both the air inlet and the air outlet to define an airflow path through the heater assembly; providing a heater mount and mounting the heating chamber on the heater mount; providing a seal to seal the airflow path and mounting the seal on the heater mount so as to be spaced from the heating chamber; and mounting the first and second heater casings together to enclose the heating chamber and the heater mount.

[0073] The heating chamber may be mounted on the heater mount by a press fit. The heating chamber may be press-fit into a recess on the second side of the heater mount.

[0074] The heating chamber may be attached to the second heater casing by a press fit. The heating chamber may be press-fit into a recess disposed on an inner surface of the second heater casing.

[0075] The first and second heater casings may be attached to one another using fasteners. A compressive force may be applied to the heater assembly prior to attaching the first and second heater casings to one another. The first and second heater casings may be attached to one another using fasteners while the compressive force is applied. The compressive force may be released after the fasteners are attached.

[0076] Features described with respect to one of the above embodiments may equally be applied to other embodiments of the present disclosure.

[0077] The invention is defined in the claims. However, below is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein.

[0078] Example 1: A heater assembly for an aerosol generating device, the heater assembly comprising a first heater casing including an air inlet, 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 inlet and the aerosol outlet to define an airflow path through the heater assembly. Example 2: The heater assembly according to example 1, further comprising a heater mount, the heating chamber being mounted on the heater mount, and a seal for sealing the airflow path, the seal being mounted on the heater mount such that it is spaced from the heating chamber. Example 3: A heater assembly according to example 2, wherein the first and second heater casings are attached to one another to enclose the heating chamber and the heater mount, and a seal is disposed between the heater mount and an inner surface of one of the first and second heater casings. Example 4: The heater assembly according to example 2 or 3, wherein a seal is disposed between the heater mount and the inner surface of the first heater casing. Example 5: A heater assembly according to any of claims 2-4, wherein the seal is attached to a first side of the heater mount and the heating chamber is attached to a second side of the heater mount, the second side being axially opposite the first side. Example 6: The heater assembly according to any of Examples 2-5, wherein the heater mount is disposed upstream of the heating chamber. Example 7: The heater assembly according to any of examples 2-6, wherein the heater mount comprises a polymer. Example 8: The heater assembly according to any of Examples 2-7, wherein the seal is disposed at a distance of at least 2 millimeters from the heating chamber. Example 9: The heater assembly according to example 8, wherein the seal is disposed at a distance of at least 4 millimeters from the heating chamber. Example 10: The heater assembly according to example 8 or 9, wherein the seal is disposed at a distance of 4 to 6 millimeters from the heating chamber. Example 11: The heater assembly according to any of Examples 2-10, wherein the seal comprises an elastomeric material. Example 12: The heater assembly according to any of Examples 2-11, wherein the seal comprises a polymer having a Shore hardness between 30A and 90A. Example 13: The heater assembly according to any of embodiments 2-12, wherein the seal is compressed within the heater assembly. Example 14: A heater assembly according to any of Examples 2-13, wherein the seal has an uncompressed thickness of 0.5mm to 2mm. Example 15: A heater assembly according to any of Examples 2-14, wherein the first heater casing, the second heater casing, the heating chamber, and the heater mount each have an airflow channel, and the airflow channels communicate to define an airflow path through the heater assembly. Example 16: The heater assembly according to any of Examples 1-15, wherein the heating chamber comprises a tubular heating chamber. Example 17: The heater assembly according to example 16, 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 a region between the two ends of the tubular heating chamber. Example 18: The heater assembly according to example 16 or 17, wherein each end of the tubular heating chamber is flared or funnel shaped. Example 19: The heater assembly according to example 18, wherein the axial length of the flared or funnel-shaped end of the tubular heating chamber is between 0.5 percent and 10 percent of the overall length of the tubular heating chamber. Example 20: A heater assembly according to Examples 16 or 17, wherein each end of the tubular heating chamber has a stepped or hemmed profile. Example 21: 21. The heater assembly of embodiment 20, wherein the axial length of the stepped or beveled end of the tubular heating chamber is between 0.5 percent and 10 percent of the overall length of the tubular heating chamber. Example 22: An aerosol generating device comprising a heater assembly according to any one of Examples 1 to 21 and a power supply for supplying power to the heater assembly. Example 23: 1. A method of manufacturing a heater assembly for an aerosol generating device, the method comprising: providing a first heater casing including an air inlet; providing a second heater casing including an aerosol outlet; providing a heating chamber for heating an aerosol-forming substrate, the heating chamber being disposed in fluid communication with both the air inlet and the air outlet to define an airflow path through the heater assembly; providing a heater mount and mounting the heating chamber on the heater mount; providing a seal to seal the airflow path, the seal being mounted on the heater mount so as to be spaced from the heating chamber; and attaching the first and second heater casings together to enclose the heating chamber and the heater mount. Example 24: The method according to example 23, wherein the heating chamber is mounted on the heater mount by press fitting. Example 25: The method according to example 23 or 24, wherein the heating chamber is attached to the second heater casing by a press fit.

[0079] The embodiments will now be further described with reference to the figures. [Brief description of the drawings]

[0080] [Figure 1] FIG. 1 is a longitudinal cross-section of a heater assembly according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is an exploded perspective view of the heater assembly of FIG. 1 prior to assembly, showing axially spaced components of the heater assembly. [Diagram 3] Figures 3A-3C are schematic cross-sectional views of a portion of the heater assembly contained within the dotted box labeled A in Figure 1, illustrating several ways in which the heater assembly seals help accommodate length tolerances. Figure 3D is a schematic cross-sectional view of a portion of the heater assembly contained within the dotted box labeled A in Figure 1, illustrating how the heater assembly seals help accommodate tilt tolerances. [Figure 4] 4A and 4B are side views of two exemplary heating chambers for use in a heater assembly according to the present disclosure. [Diagram 5] Figures 5A-5C are schematic cross-sectional partial views of a known tubular heating chamber illustrating problems that can arise due to manufacturing tolerances as a result of press-fitting the heating chamber into the heater casing, and Figure 5D is a schematic cross-sectional view of the top of the heating chamber of Figure 4A showing its press-fit engagement within a recess in the heater casing. [Figure 6] FIG. 6 is a schematic cross-sectional view showing the interior of an aerosol generating device and an aerosol-generating article received within the aerosol generating device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0081] 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, a heating chamber 6 for heating an aerosol-forming substrate, and a heater mount 8. The first heater casing 2 includes a first hollow shell section 2a and a first tubular section 2b. The first hollow shell section 2a has an interior cavity 2c surrounding the heater mount 8. An air inlet (not shown) is disposed at a distal end of the first tubular section 2b, which extends distally away from the first hollow shell section 2a in a direction parallel to the longitudinal axis XX of the heater assembly 1.

[0082] The second heater casing 4 includes a second hollow shell section 4a and a second tubular section 4b. The second hollow shell section 4a has an internal cavity 4c that surrounds the heating chamber 6. An aerosol outlet 10 is disposed at a proximal end of the second tubular section 4b, which extends proximally away from the second 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. The first heater casing 2 and the second heater casing 4 are attached to each other to enclose the heating chamber 6 and the heater mount 8.

[0083] The heating chamber 6 comprises a tubular heating chamber made from a stainless steel tube. The ends 6a, 6b of the tubular heating chamber 6 are flared or funnel-shaped, for reasons discussed in more detail below. A heating element (not shown) is disposed around the outer surface of the heating chamber to heat the heating chamber 6, which in turn heats an aerosol-forming substrate (not shown) received within the interior space of the tubular heating chamber 6. The heating element typically comprises a heat-resistant flexible polyimide film with resistive heating tracks forming a serpentine pattern on the film. The resistive heating tracks are connected to a power supply (not shown) and generate heat when an electric current is passed through the resistive heating tracks. Although not shown in FIG. 1, the heating element is disposed around substantially the entire length of the tubular heating chamber 6, except for the funnel-shaped ends, to heat substantially the entire length of the tubular heating chamber 6.

[0084] The first heater casing 2 and the second heater casing 4 are made of polyetheretherketone (PEEK) for its advantageous mechanical and thermal insulating properties. The walls of the internal cavities 2c and 4c of the first and second heater casings, respectively, are radially spaced from the heating chamber 6 and the heater mount 8 to define a hollow air space 13 around the heating chamber 6 and the heater mount 8. 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 exterior of the heater assembly 1 and the aerosol generating device.

[0085] The heater mount 8 is disposed within the first heater casing 2. A first side 8a of the heater mount 8 is disposed adjacent to the base or distal end wall of the first hollow shell section 2a. The heating chamber 6 is mounted on a second side 8b of the heater mount 8, the second side 8b being axially opposite the first side 8a in a direction parallel to the longitudinal axis XX of the heater assembly 1. The first end 6a of the heating chamber 6 is press-fitted into a first recess 14 formed in the second side 8b of the heater mount 8. The second end 6b of the heating chamber 6 is press-fitted into a second recess 16 formed in the second heater casing 4 at the top or proximal end wall of the second hollow shell section 4a and at the distal end of the second tubular section 4b. The heater mount 8 is made of PEEK for its advantageous mechanical and thermal insulating properties.

[0086] The heater mount 8 has an internal airflow channel 18 that extends axially along the length of the heater mount 8 in a direction parallel to the longitudinal axis XX of the heater assembly 1. The airflow channel 18 of the heater mount 8 is in fluid communication with an airflow channel 20 defined by the interior 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. Additionally, the first tubular section 2b of the first heater casing 2 has an airflow channel 22, and the second tubular section 4b of the second heater casing 4 has an airflow channel 24. The airflow channels 22, 18, 20 and 24 of the first tubular section 2b, the heater mount 8, the tubular heating chamber 6 and the second tubular section 4b, respectively, are in fluid communication with each other to define an airflow path 26 through the heater assembly 1 between the air inlet (not shown) and the aerosol outlet 10. The heating chamber 6 is therefore in fluid communication with both the air inlet and the aerosol outlet 10 .

[0087] The heater mount 8 has a step or stop 28 formed in an inner surface of the heater mount 8 within its airflow channel 18. The stop 28 is arranged to engage a distal end of an aerosol-generating article (not shown) to prevent the distal end of the aerosol-generating article from moving beyond the stop 28 and to precisely position an aerosol-forming substrate provided in the aerosol-generating article within the heating chamber 6.

[0088] An elastomeric polymer seal 30 in the form of an O-ring made from ethylene propylene diene monomer (EPDM) rubber is mounted on the heater mount 8. The seal 30 is mounted on a first side 8a of the heater mount 8 between the heater mount 8 and a distal end wall of the first hollow shell section 2a of the first heater casing 2. The O-ring seal surrounds the airflow path 26 through the heater assembly 1. A recess 32 is formed in the first side 8a of the heater mount 8 to seat the seal 30. The seal 30 has a Shore hardness of 70A as determined by technical standard ISO 868 Type A. This hardness has been found to be soft enough to accommodate lengthwise and tilt tolerances, as discussed in more detail below, yet hard enough to apply force to the heater assembly 1 to provide a seal of the airflow path 26 and the integrity of the heater assembly 1. The seal 30 has an uncompressed thickness or diameter of 1 millimeter. This thickness has also been found to be adequate to accommodate length and tilt tolerances and to apply force to the heater assembly 1 to provide sealing of the airflow path 26 and integrity of the heater assembly 1.

[0089] By mounting the seal 30 on a first side 8a of the heater mount 8 and mounting the heated chamber 6 on a second side 8b of the heater mount 8, the seal 30 is spaced or distanced from the heated chamber 6. In this arrangement, at least a portion of the heater mount 8 is disposed between the seal 30 and the heated chamber 6. This reduces heat transfer to the seal 30 and helps to keep the seal 30 cooler than the heated chamber 6. As mentioned above, the heater mount is made from PEEK, which has a lower thermal conductivity than the heated chamber, which is made from stainless steel. This further reduces heat transfer to the seal 30 and helps to keep the seal 30 cooler than the heated chamber. Thus, in the arrangement of FIG. 1, the seal 30 is at a lower temperature than if it were in direct contact with the heated chamber, which helps to maintain the integrity of the seal 30 and provide an improved seal.

[0090] The seal 30 is resilient and is compressed to some extent when the heater assembly 1 is assembled. The resilience of the seal 30 exerts an axial force on the heater mount 8 in a direction parallel to the longitudinal axis XX of the heater assembly 1. As the heater mount 8 is axially aligned with the heating chamber 6, which in turn is axially aligned with the second tubular section 4b, the seal 30 sealingly engages these components together to seal the airflow path 26 and assist in reducing the possibility of aerosols leaking from the airflow path 26 at the tolerance point between the two components. The seal 30 also provides an airtight seal between the heater mount 8 and the first heater casing 2.

[0091] FIG 2 shows an exploded perspective view of the heater assembly 1 of FIG 1 prior to assembly. The components of the heater assembly 1, namely, the first heater casing 2, the heater mount 8, the seal 30, the heating chamber 6 and the second heater casing 4, are shown axially spaced apart in FIG 2. To assemble the heater assembly 1, first the seal 30 is attached to the first side 8a of the heater mount 8. The heater mount 8 and seal 30 subassembly is then installed within the first hollow shell section 2a of the first heater casing 2. A hollow plug 8c extending distally from the first side 8a of the heater mount 8 is press-fit into an internal recess (not shown) formed in the proximal end of the first tubular section 2b.

[0092] The heating chamber 6 is then press-fitted into an internal recess (not shown in FIG. 2, but see second recess 16 in FIG. 1) formed in the proximal end wall of the second hollow shell section 4a of the second heater casing 4. A guide (not shown) is inserted internally through the second tubular section 4b of the second heater casing 4 and through the internal space within the heating chamber 6 to keep the components axially aligned. The subassembly of the second heater casing 4 and the heating chamber 6 is then mounted onto the subassembly including the first heater casing 2, the seal 30 and the heater mount 8. The distal end of the guide is inserted into the internal airflow channel (not shown) of the heater mount 8 to keep the components aligned. The first heater casing 2 and the second heater casing 4 are then attached to each other using two screws 34 and washers 36. The guide is then removed. Attachment of the first heater casing 2 and the second heater casing 4 compresses the seal 30, which then applies an axial force as described above, maintaining the components of the heater assembly 1 in axial sealing engagement and sealing the airflow path through the heater assembly. Thus, the airflow path is sealed between the air inlet 38 disposed at the distal end of the first tubular section 2b of the first heater casing 2 and the aerosol outlet 10 disposed at the proximal end of the second heater casing 4.

[0093] 3A-3C are schematic cross-sectional views of a portion of the heater assembly 1 contained within the dotted box labeled A in FIG. 1, illustrating some ways in which the seals of the heater assembly serve to accommodate longitudinal tolerances. Referring to FIG. 3A, FIG. 3A shows the lower portion of the tubular heating chamber 6 engaged with the upper or second side 8b of the heater mount 8. The seal 30 is disposed on the lower or first side of the heater mount 8, between the heater mount 8 and the first heater casing 2. The seal 30 has a circular cross-section in the longitudinal plane in its uncompressed state, but is axially compressed to some extent in a direction parallel to the longitudinal axis XX (see FIG. 1) of the heater assembly when the heater assembly is assembled. Thus, in FIG. 3A, the seal 30 is shown to have a flat or elliptical cross-section, illustrating the effect of axial compression.

[0094] In the example of Figure 3A, the tubular heating chamber 6, heater mount 8 and second heating casing 2 are at the exact specified design length. In Figure 3A, horizontal dashed line BB indicates the surface level where heating chamber 6 and heater mount 8 intersect. Horizontal line BB also extends across Figures 3B and 3C and serves as a datum indicating where heating chamber 6 and heater mount 8 would intersect if heating chamber 6 were at the exact length.

[0095] In Fig. 3B, the heating chamber 6 is too short, i.e., the length of the heating chamber 6 is less than its specified design length by a distance d1. However, that length is still within manufacturing tolerances. In this situation, to accommodate the shortfall in length caused by the manufacturing tolerances in the length direction, the seal 30 is axially compressed less by an amount corresponding to the distance d1, compared to its compressed state in Fig. 3A. Even in its less compressed state in Fig. 3B, the seal still has sufficient compression to axially engage the components of the heater assembly to seal the airflow path through the heater assembly, and still provide an airtight seal between the heater mount 8 and the first heater casing 2.

[0096] In Fig. 3C, the heating chamber 6 is too long, i.e., the length of the heating chamber 6 is greater than its specified design length by a distance d2. However, that length is still within manufacturing tolerances. In this situation, to accommodate the excess length caused by the manufacturing tolerances in the length direction, the seal 30 is highly axially compressed by an amount corresponding to the distance d2, compared to its compressed state in Fig. 3A. Even in its highly compressed state, the seal is still able to axially engage the components of the heater assembly to seal the airflow path through the heater assembly, and still provide an airtight seal between the heater mount 8 and the first heater casing 2.

[0097] Of course, the elasticity and thickness of the seal 30 may be used to compensate for longitudinal tolerances of other components in addition to the heating chamber 6, such as the heater mount 8 or the second heating casing 2, as shown in Figures 3B and 3C.

[0098] FIG. 3D is a schematic cross-sectional view of a portion of the heater assembly 1 contained within the dotted box labeled A in FIG. 1, similar to FIGS. 3A-3C. This view shows how the seal 30 of the heater assembly helps to absorb tilt tolerances. In FIG. 3D, the right side 2r of the first heater casing 2 is at an axial level that differs by a distance d3 from the left side 2l of the first heater casing 2 in a direction parallel to the longitudinal axis XX (see FIG. 1) of the heater assembly. This is due to manufacturing tilt tolerances, and if the heater mount 8 were mounted directly on the first heater casing 2, the heater mount 8 and the heating chamber 6 would be tilted. The dashed line CC indicates the exact specified design height or level of the first heater casing. In this situation, the left side 30l of the seal 30 has the standard amount of compression shown in FIG. 3A. The right side 30r of the seal 30 is further compressed axially compared to the left side 30r of the seal 30 by an amount equivalent to the distance d3 to absorb the level difference caused by the tilt manufacturing tolerance. In this condition, the seal is still able to axially engage the components of the heater assembly to seal the airflow path through the heater assembly and still provide an airtight seal between the heater mount 8 and the first heater casing 2.

[0099] It should be noted that Figures 3A-3D are schematic and not to scale: for clarity, the figures have been simplified by omitting some details and the sizes of features have been altered or exaggerated.

[0100] 4A and 4B are side views of two exemplary heating chambers for use in a heater assembly according to the present disclosure. Referring to FIG. 4A, FIG. 4A shows a first embodiment of a heating chamber 6A. The heating chamber 6A comprises a stainless steel tube having a circular cross section. A hollow interior space within the tubular heating chamber 6A has an inner diameter substantially corresponding to an outer diameter of an aerosol-generating article (not shown) such that the tubular heating chamber 6A can receive the aerosol-generating article within the interior space. A portion 7a of the heating chamber 6A at each end of the heating chamber 6A is flared outwardly to form a funnel shape at each end of the heating chamber 6A. The flared portions 7a each have a length l1, and the percentage of the total length l of the heating chamber 6A constituted by each of the flared portion lengths l1 may be in the range of 1 to 5 percent. The flared ends 7a of the heating chamber 6A each form an angle of about 45 degrees with the longitudinal axis of the heating chamber 6A. As a result of the flared ends 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 ends 7a.

[0101] A portion 9a of the heating chamber 6A between the two flared ends 7a has straight sides parallel to the longitudinal axis of the heating chamber 6A. The straight portion 9a of the heating chamber 6A has a length l2 that substantially corresponds to the length of an aerosol-forming substrate provided in an aerosol-generating article configured to be received in 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 connection with FIG. 1). The flared portion 7a of the heating chamber 6A is not surrounded by the heating element and acts as a spacer between the ends of the heating element and the components that hold the heating chamber 6A, i.e., the heater mount and the second heater casing, helping to prevent direct contact between these components and the heating element.

[0102] Referring to FIG. 4B, FIG. 4B shows a second embodiment of the heating chamber 6B. The heating chamber 6B has essentially the same structure as the heating chamber 6A of FIG. 4A, except that instead of flared ends, the heating chamber 6B has stepped or crimped ends 7b. That is, a portion 7b of the heating chamber 6B at each end of the heating chamber 6B is stepped or crimped radially outward to form a step at each end of the heating chamber 6B. The stepped portions 7b each have a length l1, and the proportion of the total length l of the heating chamber 6B constituted by each of the stepped portions lengths l1 may be in the range of 1 to 5 percent. As a result of the stepped ends 7b, the outer diameter D at the two ends of the heating chamber 6B is greater than the outer diameter d of the heating chamber 6B between the two stepped ends 7b.

[0103] A portion 9b of the heating chamber 6B between the two stepped ends 7b has straight sides parallel to the longitudinal axis of the heating chamber 6B. The straight portion 9b of the heating chamber 6B has a length l2 that corresponds substantially to the length of an aerosol-forming substrate provided in an aerosol-generating article configured to be received in the heating chamber 6B. Substantially all of the length l2 of the straight portion 9b of the heating chamber 6B is surrounded by a flexible heating element (not shown, but described above in connection with FIG. 1). The stepped portion 7b of the heating chamber 6B is not surrounded by the heating element and acts as a spacer between the ends of the heating element and the components that hold the heating chamber 6B, i.e., the heater mount and the second heater casing, 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 straight portion 9b, providing an inclined or curved transition between the outer diameter D of each of the stepped portions and the outer diameter d of the straight portion.

[0104] 5A-5C are schematic cross-sectional views of a portion of a known tubular heating chamber having a straight tubular wall, illustrating problems that can arise due to manufacturing tolerances during press fitting of such a heating chamber with a heater casing. Manufacturing tolerances can cause component dimensions to be larger or smaller than the specified design length, leading to problems in connecting closely fitted components. With rapid manufacturing techniques such as injection molding, it is more difficult to achieve very precise manufacturing tolerances.

[0105] Referring to FIG. 5A, FIG. 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 straight, i.e., has a constant outer diameter along its entire length, and the tubular heating chamber 6 does not have flared or stepped ends like the tubular heating chambers 6A and 6B of FIGS. 4A and 4B. As seen in FIG. 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 during insertion of the aerosol-generating article into the heating chamber 6. As a result, a portion of the thickness t of each of the walls, i.e., the end face of the heating chamber 6, protrudes into the interior space defined by the inner diameter d2 of the opening 15. This forms a sharp step 17 at the opening 15, which may damage the aerosol-generating article when it is inserted through the opening 15, or may prevent the aerosol-generating article from being inserted. A similar situation may arise if the width w of the recess 16 is smaller than the wall thickness t of the tubular heating chamber 6. In this case, there is not enough space in the recess 16 to receive the end of the tubular heating chamber 6, and as a result, the end protrudes into the interior space defined by the inner diameter d2 of the opening 15.

[0106] Of course, a similar situation to that shown in Figure 5A may 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 suffer from problems with debris or deposits building up in the gap formed by the step, which may be difficult to remove or clean using a cleaning tool.

[0107] Figure 5B shows the lower part of a known or conventional tubular heating chamber 6 press-fitted into a recess 14 in the lower heater casing 2. As 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 an opening 19 formed in the lower heater casing 2, through which a portion of the aerosol-generating article protrudes when the aerosol-generating article is properly positioned in the heating chamber 6. As a result of a sharp step 21 formed in the opening 19, the aerosol-generating article may be damaged as it passes through the opening 19, or may be prevented from being fully inserted.

[0108] Of course, a similar situation to that shown in Figure 5B may 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 suffer from problems with debris or deposits building up in the gap formed by the step, which may be difficult to remove or clean using a cleaning tool.

[0109] Figure 5C shows the top of a known or conventional tubular heating chamber 6 press-fitted into a recess 16 in the upper heater casing 4. As in Figures 5A and 5C, the entire length of the tubular heating chamber 6 is straight. The outer diameter d5 of the tubular heating chamber 6 is smaller than the inner diameter of the opening 15 in the heater casing 4, through which the aerosol-generating article passes during insertion into the heating chamber 6. As a result, the tubular heating chamber 6 simply passes through the opening 15, and therefore a press-fit is not possible in this situation.

[0110] Figure 5D is a schematic cross-sectional view of the top of the tubular heating chamber 6A of Figure 4A. As mentioned above, the tubular heating chamber 6A has a wall with a funnel-shaped or flared end 7a. The flared end 7a is press-fitted into a recess 16 of the second heater casing 4. The outer diameter D of the flared end 7a is larger than the outer diameter d of the portion of the tubular heating chamber 6A between the two flared ends 7a (only one flared end is visible in Figure 5D). The outer diameter D of the flared end 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 during insertion of the aerosol-generating article into the heating chamber 6. The outer diameter D of the flared end 7a is larger than the inner diameter d7 of the opening 15, even when taking into account the radial or lateral manufacturing tolerances of the inner diameter d7.

[0111] The arrangement of FIG. 5D significantly reduces the possibility that a portion of the end surface 6c of the wall of the tubular heating chamber 6A will protrude into the diameter d7 and the cross-section of the airflow path defined by the diameter d7 in FIG. 5D. Additionally, the end surface 6c of the wall of the tubular heating chamber 6A is angled away from the cross-section of the airflow path defined by the diameter d7, further reducing the possibility that a portion of the end surface 6c of the wall of the tubular heating chamber 6A will protrude into the airflow path. The arrangement of FIG. 5D, and in particular the use of a tubular heating chamber 6A having a flared or funnel-shaped end 7a, is amenable to rapid manufacturing techniques, as it allows the use of components with larger radial or lateral tolerances. The arrangement of FIG. 5D also significantly reduces the risk of damage to the aerosol-generating article when it is inserted into the heating chamber 6A.

[0112] It will be appreciated that the tubular heating chamber 6B of Figure 4B may also be used in the arrangement of Figure 5D in place of heating chamber 6A to achieve the same benefits. The larger outer diameter D of the stepped end 7b of heating chamber 6B reduces the likelihood that a portion of the end face of the wall of tubular heating chamber 6B will protrude into diameter d7 of Figure 5D and into the airflow path. Heating chamber 6B also allows for the use of components with larger radial or lateral tolerances, reducing the risk of damage to the aerosol-generating article when it is inserted into heating chamber 6B.

[0113] It should be noted that Figures 5A-5D are schematic and not to scale: for clarity, the figures have been simplified by omitting some details and the sizes of features have been altered or exaggerated.

[0114] Figure 6 is a schematic cross-sectional view of an aerosol generating device 100 and an aerosol-generating article 200 received within the aerosol generating device 100. Together, the aerosol generating device 100 and the aerosol-generating article 200 form an aerosol generating system. In Figure 6, the aerosol generating device 100 is shown in a simplified manner. In particular, the elements of the aerosol generating device 100 are not drawn to scale. Furthermore, elements that are not relevant for understanding the aerosol generating device 100 have been omitted.

[0115] The aerosol generating device 100 comprises a housing 102 that houses the heater assembly 1 of FIG. 1, a power supply 103, and a control circuit 105. In FIG. 6, a first heater casing 2, a heating chamber 6, a heater mount 8, and a second heater casing 4 are shown. As described above in relation to FIG. 1, the heating chamber 6 has a flexible heating element (not shown) disposed therearound for heating 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.

[0116] The housing 102 has an opening 104 at the proximal or mouth end of the aerosol generating device 100, through which the aerosol-generating article 200 is received. The opening 104 is connected to the opening 12 of the heater assembly 1 of FIG. 1, through which the aerosol exits the heater assembly 1. However, it will be appreciated that the aerosol exits the aerosol generating device 100 mostly through the heater assembly 1 and the aerosol-generating article 200. The housing 102 further includes an air inlet 106 at the distal end of the aerosol generating device 100. The air inlet 106 is connected to an air inlet disposed 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 inlet 106 to the heating chamber 6.

[0117] 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 are substantially cylindrical elements, each having substantially the same diameter. The components are arranged consecutively in coaxial alignment and abutting contact and 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 crimped sheets of homogenized tobacco material surrounded by a wrapper (not shown). The crimped 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.

[0118] The distal end of the aerosol-generating article 200 is inserted into the aerosol-generating device 100 through the opening 104 in the housing 102 and pushed into the aerosol-generating device 100 until it engages a stop (not shown in FIG. 6 ) disposed on the heater mount 8, up to which point the aerosol-generating article 200 is fully inserted. The stop serves to precisely position the aerosol-forming substrate 204 within the heating chamber 6 so that the heating chamber 6 can heat the aerosol-forming substrate 204 to form an aerosol.

[0119] The aerosol generating device 100 may further include a sensor (not shown) for detecting the presence of the aerosol generating article 200, a user interface (not shown) such as a button for activating the heating element, and a display or indicator (not shown) for presenting information to the user, such as, for example, remaining battery power, heating status, and error messages.

[0120] In use, a user inserts the aerosol-generating article 200 into the aerosol-generating device 100 as shown in FIG. 6. The user then initiates a heating cycle by activating the aerosol-generating device 100, for example, by pressing a switch to turn the device on. In response, the control circuitry 105 controls the supply of power from the power source 103 to a heating element (not shown) to heat the heating element, which in turn heats the heating chamber 6. During the heating cycle, the heating element heats the heating chamber 6 to a predetermined temperature, or to a predetermined temperature range according to a temperature profile. The heating cycle may last for approximately six minutes. Heat from the heating chamber 6 is transferred to the aerosol-forming substrate 204, which releases volatile compounds from the aerosol-forming substrate 204. The volatile compounds form an aerosol in the aerosolization 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 the lips of his or her mouth and smokes or inhales through the mouthpiece filter 208. The generated aerosol is then drawn through the mouthpiece filter 102 and into the user's mouth.

[0121] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like, should be understood in all instances as modified by the term "about." Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A ± five percent (5%). Within this context, the number A may be considered to include values ​​that are within the typical standard error for the measurement of the property that the number A modifies. The number A may, in some cases, as used in the appended claims, deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel properties of the claimed invention. Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. 1. A heater assembly for an aerosol generating device, the heater assembly comprising: a first heater casing including an air inlet; a second heater casing including an aerosol outlet; a heating chamber for heating an aerosol-forming substrate, said heating chamber being in fluid communication with both the air inlet and the aerosol outlet to define an airflow path through said heater assembly; the heater assembly further comprising: a heater mount, the heating chamber being mounted on the heater mount; and a seal for sealing the airflow path; the seal is mounted on the heater mount such that the seal is spaced from the heating chamber; the seal is attached to a first end of the heater mount and the heating chamber is attached to a second end of the heater mount, the second end being axially opposite the first end, a heater assembly.

2. 2. The heater assembly of claim 1, wherein the first and second heater casings are attached to one another to enclose the heating chamber and the heater mount, and the seal is disposed between the heater mount and an interior surface of one of the first and second heater casings.

3. The heater assembly of claim 1 or 2, wherein the seal is disposed between the heater mount and an inner surface of the first heater casing.

4. The heater assembly of claim 1 or 2, wherein the heater mount is disposed upstream of the heating chamber.

5. The heater assembly of claim 1 or 2, wherein the heater mount comprises a polymer.

6. The heater assembly of claim 1 or 2, wherein the seal is disposed at a distance of between 4 millimeters and 6 millimeters from the heating chamber.

7. The heater assembly of claim 1 or 2, wherein the seal comprises a polymer having a Shore hardness of 30A to 90A.

8. The heater assembly of claim 1 or 2, wherein the seal has an uncompressed thickness of between 0.5 mm and 2 mm.

9. 3. The heater assembly of claim 1 or 2, wherein the first heater casing, the second heater casing, the heating chamber, and the heater mount each have an airflow channel, the airflow channels communicating to define the airflow path through the heater assembly.

10. The heater assembly of claim 1 , wherein the heating chamber comprises a tubular heating chamber.

11. 11. The heater assembly of claim 10, wherein a diameter of the tubular heating chamber at each end of the tubular heating chamber is greater than a diameter of the tubular heating chamber in a region between the two ends of the tubular heating chamber.

12. 12. The heater assembly of claim 10 or 11, wherein each end of the tubular heating chamber is flared or funnel shaped.

13. 13. The heater assembly of claim 12, wherein the axial length of the flared or funnel-shaped end of the tubular heating chamber is between 0.5 percent and 10 percent of the overall length of the tubular heating chamber.

14. The heater assembly of claim 11 , wherein each end of the tubular heating chamber has a stepped or hemmed profile.

15. 15. The heater assembly of claim 14, wherein the axial length of the stepped or crimped end of the tubular heating chamber is between 0.5 percent and 10 percent of the overall length of the tubular heating chamber.

16. The heater assembly of claim 1 or 2, wherein the heating chamber is configured to receive at least a portion of an aerosol-generating article.

17. An aerosol generating device, comprising: A heater assembly according to claim 1 or 2; a power supply for supplying power to the heater assembly.

18. 1. A method of manufacturing a heater assembly for an aerosol generating device, the method comprising: providing a first heater casing including an air inlet; providing a second heater casing including an aerosol outlet; providing a heating chamber for heating an aerosol-forming substrate, said heating chamber being disposed in fluid communication with both said air inlet and said air outlet to define an airflow path through a pre-heater assembly; providing a heater mount and mounting the heating chamber on the heater mount; providing a seal to seal the airflow path, and mounting the seal on the heater mount such that the seal is spaced from the heating chamber; the seal being mounted on a first end of the heater mount, and the heating chamber being mounted on a second end of the heater mount, the second end being axially opposite the first end; and attaching the first and second heater casings together to enclose the heating chamber and heater mount.

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