HEATER ASSEMBLY HAVING SEPARATED SEALED ELEMENTS - Patent application

Abstract

1. A heater assembly (410) for an aerosol generating device, comprising: a first heater casing (412) having an air inlet (418); a second heater casing (414) having an aerosol outlet (420); a tubular heater (416) for heating an aerosol-forming substrate; an airflow path (422) extending through the heater assembly from the air inlet to the aerosol outlet, the airflow path (422) passing through the first heater casing, the tubular heater, and the second heater casing; a first sealing element (426) configured to seal the first heater casing to the tubular heater; and a second sealing element (424) configured to seal the second heater casing to the tubular heater, wherein the first sealing element and the second sealing element are separated from 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 including 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 deliver the aerosol into a user's mouth. The present disclosure also relates to an aerosol generating system including the aerosol generating device, and the 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 insertion of the aerosol-generating article into a heating chamber of the aerosol-generating device. A heating element is typically disposed within or around the heating chamber to heat the aerosol-forming substrate when 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 may form part of the airflow path through the aerosol generating device. One method of attaching the heating chamber to the housing of the aerosol generating device is by mechanical press-fit. However, due to manufacturing tolerances, it is difficult to achieve an airtight seal between the housing and the heating chamber using a mechanical press-fit, and gaps may remain between the housing and the heating chamber through which aerosol may leak from the heating chamber and the airflow path into the portion of the housing surrounding the heating chamber. The leaking aerosol may condense and form a slurry within the portion of the housing surrounding the heating chamber. When a consumer uses the aerosol generating device, the slurry may be repeatedly heated, which may produce undesirable by-products. These by-products may enter the airflow path through the gap between the housing and the heating chamber and adversely affect the consumer's experience using the aerosol generating device.

[0004] Furthermore, gaps between the housing and the heating chamber can result in heat loss from the heating chamber, which can reduce the thermal efficiency of the device and the heat available for heating the aerosol-forming substrate, which can also degrade the consumer experience.

[0005] 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 the user. Summary of the Invention

[0006] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generating device. The heater assembly may include a first heater casing. The first heater casing may include an air inlet. The heater assembly may include a second heater casing. The second heater casing may include an aerosol outlet. The heater assembly may include a tubular heater for heating an aerosol-forming substrate to form an aerosol. The heater assembly may include an airflow path. The airflow path may extend through the heater assembly from the air inlet to the aerosol outlet. The airflow path may pass through the first heater casing. The airflow path may pass through the tubular heater. The airflow path may pass through the second heater casing. The heater assembly may include a first sealing element. The first sealing element may be configured to seal the first heater casing to the tubular heater. The heater assembly may include a second sealing element. The second sealing element may be configured to seal the second heater casing to the tubular heater. The first sealing element may be separated from the airflow path.The second sealing element may be separated from the airflow path.

[0007] According to one embodiment of the present disclosure, there is provided a heater assembly for an aerosol generating device. The heater assembly includes a first heater casing with an air inlet, a second heater casing with an aerosol outlet, a tubular heater for heating an aerosol-forming substrate to generate an aerosol, and an airflow path extending through the heater assembly from the air inlet to the aerosol outlet, the airflow path passing through the first heater casing, the tubular heater, and the second heater casing. The heater assembly further includes a first sealing element configured to seal the first heater casing to the tubular heater, and a second sealing element configured to seal the second heater casing to the tubular heater. The first sealing element and the second sealing element are separated from the airflow path.

[0008] Advantageously, the first and second sealing elements provide a seal around the tubular heater. This helps prevent leakage of aerosol from the tubular heater into the first and second heater casings, reducing the possibility of slurry formation within the first and second heater casings and the generation of undesirable by-products. Furthermore, the first and second sealing elements are separated from the airflow path, which prevents contact between the heated aerosol and the air and the sealing elements. This helps reduce the possibility of the sealing elements being degraded by the aerosol and releasing undesirable by-products. Furthermore, the sealing elements restrict undesirable by-products from entering the aerosol or airflow within the airflow path. Additionally, the first and second sealing elements are separated from the airflow path, preventing contact between the aerosol and the first and second sealing elements. This helps prevent the aerosol from degrading the sealing elements and reduces the possibility of any material released from the sealing elements entering the airflow path. Another advantage of the first and second sealing elements providing a seal around the tubular heater is that they help reduce leakage of heated aerosol and air from the tubular heater, which improves the energy efficiency of the heater assembly.

[0009] As used herein, when defining the location of the first and second sealing elements relative to the airflow path, the term "separate" means that there is a physical barrier between the sealing elements and the airflow path. For example, a tubular heater may act as a physical barrier between the first and second sealing elements and the airflow path, i.e., the walls of the tubular heater may be disposed between the first and second sealing elements and the airflow path. Additionally, the interfaces between the first and second heater casings, or the first and second heater casings and the tubular heater, may act as a physical barrier between the first and second sealing elements and the airflow path.

[0010] The first sealing element may comprise an annular seal. The first sealing element may be disposed between an inner surface of the first heater casing and an outer surface of the tubular heater. Advantageously, in this arrangement, the first sealing element is positioned on an opposite side of the tubular heater from the side through which the airflow path passes, such that the tubular heater acts as a physical barrier between the first sealing element and the airflow path.

[0011] The second sealing element may comprise an annular seal. The second sealing element may be disposed between the inner surface of the second heater casing and the outer surface of the tubular heater. Advantageously, in this arrangement, the second sealing element is positioned on an opposite side of the tubular heater from the side through which the airflow path passes, such that the tubular heater acts as a physical barrier between the second sealing element and the airflow path.

[0012] At least one of the first sealing element and the second sealing element may be disposed in a groove or recess formed in the inner surface of one of the first heater casing and the second heater casing, respectively. The first sealing element may be disposed in a groove or recess formed in the inner surface of the first heater casing. The second sealing element may be disposed in a groove or recess formed in the inner surface of the second heater casing. A first end of the tubular heater may be disposed in a groove or recess formed in the inner surface of the first heater casing. A second end of the tubular heater may be disposed in a groove or recess formed in the inner surface of the second heater casing. Advantageously, the groove provides an effective way of holding the sealing element in place and also helps to protect the sealing element. Advantageously, the groove provides an effective way of holding the tubular heater in place.

[0013] The first heater casing may include a tube holder for holding the tubular heater. The airflow path may pass through the tube holder. The tube holder provides an effective manner of holding or supporting the tubular heater. The tube holder also serves to distance the tubular heater from the remainder of the first heater casing, insulating or isolating the remainder of the first heater casing from the relatively high temperatures reached by the tubular heater.

[0014] A first sealing element may be disposed between the tube holder and the outer surface of the tubular heater, which serves to seal the tube holder component of the first heater casing to the tubular heater.

[0015] The first and second sealing elements may comprise opposing end sections of the tubular heater. The opposing end sections may be secured in sealing engagement against the inner surfaces of the first and second heater casings. Advantageously, in this arrangement, the interfaces between the first and second heater casings and the tubular heater act as a physical barrier between the first and second sealing elements and the airflow path. That is, the sealing engagement of the opposing end sections of the tubular heater with the inner surfaces of the first and second heater casings serves to seal the airflow path and protect the opposing end sections.

[0016] The opposed end sections of the tubular heater may be secured in sealing engagement within grooves or recesses formed in the interior surfaces of the first and second heater casings. Advantageously, in this arrangement, portions of the first and second heater casings around the grooves or recesses act as a physical barrier between the opposed end sections of the tubular heater and the airflow path, such that aerosols cannot contact the sealing element.

[0017] The opposed end sections of the tubular heater may be embedded within the interior surfaces of the first and second heater casings. Advantageously, in this arrangement, portions of the first and second heater casings around the embedded opposed end sections of the tubular heater act as a physical barrier between the opposed end sections of the tubular heater and the airflow path, such that aerosols cannot contact the sealing element.

[0018] The first heater casing and the second heater casing may be sealed or connected to the opposing end sections of the tubular heater by one or more of the following processes: insert molding, overmolding, hot melting, radio frequency welding, and ultrasonic welding.

[0019] The opposing end section of the tubular heater has a surface finish with an ISO roughness value in the range of N9 to N12. The surface roughness may be determined in accordance with the specifications for surface roughness set forth in ISO Standard 1302, and specifically ISO Standard 1302:1992. The surface roughness of the opposing end section may be created by any suitable manufacturing or machining process, including, but not limited to, grinding, casting, coating, cutting, etching, plastic deformation, sintering, abrasion, and erosion.

[0020] In an arrangement in which the first and second sealing elements comprise opposite end sections of the tubular heater, the heater assembly may further comprise a third sealing element configured to further seal the first heater casing to the tubular heater. The heater assembly may further comprise a fourth sealing element configured to further seal the second heater casing to the tubular heater. Advantageously, this arrangement serves to provide an additional degree of sealing of the airflow path.

[0021] The third sealing element may comprise an annular seal. The third sealing element may be disposed between an inner surface of the first heater casing and an outer surface of the tubular heater. Advantageously, in this arrangement, the third sealing element is positioned on an opposite side of the tubular heater from the side through which the airflow path passes, such that the tubular heater acts as a physical barrier between the third sealing element and the airflow path.

[0022] The fourth sealing element may comprise an annular seal. The fourth sealing element may be disposed between the inner surface of the second heater casing and the outer surface of the tubular heater. Advantageously, in this arrangement, the fourth sealing element is positioned on an opposite side of the tubular heater from the side through which the airflow path passes, such that the tubular heater acts as a physical barrier between the fourth sealing element and the airflow path.

[0023] In one embodiment, the tubular heater may be surrounded by a first heater casing and a second heater casing. Advantageously, this arrangement may help to prevent aerosol from escaping out of the airflow path and into the aerosol generating device.

[0024] In another embodiment, the heater assembly may further include a heater sleeve surrounding at least a portion of the tubular heater, the heater sleeve being disposed between the first heater casing and the second heater casing, and may help to prevent leakage of the aerosol out of the airflow path and into the aerosol generating device.

[0025] The first sealing element may engage the inner surface of the first heater casing, the outer surface of the tubular heater, and the inner or end surface of the heater sleeve. This arrangement may be useful for providing a sealing engagement between the first heater casing, the tubular heater, and the heater sleeve to seal the airflow path.

[0026] The second sealing element may engage the inner surface of the second heater casing, the outer surface of the tubular heater, and the inner surface or end surface of the heater sleeve. This arrangement may be useful for providing a sealing engagement between the second heater casing, the tubular heater, and the heater sleeve to seal the airflow path.

[0027] The first heater casing and the second heater casing are radially spaced from the tubular heater to define a cavity around the tubular heater. Advantageously, the hollow cavity helps to insulate the tubular heater, which helps to reduce heat loss from the tubular heater and also helps to reduce heat transfer to the exterior of the heater assembly.

[0028] The first heater casing and the second heater casing may be made from any suitable material. Preferably, the first heater casing and the second heater casing are made from a heat-resistant plastic capable of withstanding temperatures of at least 250 degrees Celsius, preferably at least 300 degrees Celsius, and more preferably at least 350 degrees Celsius. In one embodiment, the first heater casing and the second heater casing may be made from polyetheretherketone (PEEK). Such materials are good insulators and also help reduce the transfer of heat outside the heater assembly.

[0029] The diameter of the tubular heater at a first end of the tubular heater may be larger than the diameter along the length of the tubular heater. The diameter of the tubular heater at a second end of the tubular heater may be larger than the diameter along the length of the tubular heater. The diameter of the tubular heater at each end of the tubular heater may be larger than the diameter of the tubular heater in the region between the two ends of the tubular heater. An advantage of having the diameter of one or both ends of the tubular heater larger than the diameter of the tubular heater along the length of the tubular heater, for example, in the region between the two ends of the tubular heater, is that it allows for greater manufacturing tolerances for the tubular heater and also for other components of the heater assembly. This may aid in the assembly of the heater assembly and also reduces the number of machining or finishing steps required during the manufacture of the tubular heater.

[0030] Another advantage of making the ends of the tubular heater larger in diameter than the rest of the tubular heater is that the inner diameter at one or both ends of the tubular heater will be larger than the inner diameter of the airflow paths in other components of the heater assembly with which the tubular heater engages, such as the first heater casing and second heater casing. This helps to avoid small end surfaces of the tubular heater that could protrude or intrude into the interior spaces of the airflow paths and potentially cause damage to the aerosol-generating article when received within the tubular heater.

[0031] The outer diameter of one or both ends of the tubular heater may be at most 40 percent larger, preferably at most 35 percent larger, more preferably at most 30 percent larger, and even more preferably at most 27 percent larger than the outer diameter of the portion of the tubular heater between the two ends of the tubular heater. The outer diameter of one or both ends of the tubular heater may be 10 percent to 40 percent larger, 15 percent to 35 percent larger, 20 percent to 30 percent larger, or 25 percent to 30 percent larger than the outer diameter of the portion of the tubular heater between the two ends of the tubular heater.

[0032] One or both ends of the tubular heater may have an outer diameter of about 7.6 millimeters to about 10.7 millimeters, preferably about 9.0 millimeters to about 10.0 millimeters, and more preferably about 9.7 millimeters. The portion of the tubular heater between the two ends of the tubular heater may have an outer diameter of about 6.5 millimeters to about 8.0 millimeters, preferably about 7.0 millimeters to about 8.0 millimeters, and more preferably about 7.6 millimeters.

[0033] The inner diameter of the tubular heater between its two ends 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 tubular heater may be slightly smaller than the outer diameter of the aerosol-generating article, thereby compressing the aerosol-generating article within the tubular heater. For example, the outer diameter of the aerosol-generating article may be about 7.4 millimeters, and the inner diameter of the tubular heater may be about 7.3 millimeters. The length of the tubular heater may substantially correspond to or be substantially equal to the length of the aerosol-forming substrate provided within the aerosol-generating article.

[0034] A portion of the first end of the tubular heater may be flared or funnel-shaped. A portion of the second end of the tubular heater may be flared or funnel-shaped. A portion of each end of the tubular heater may be flared or funnel-shaped. The axial length of each portion of each end of the tubular heater that is flared or funnel-shaped may be 3.5 to 15 percent of the overall length of the tubular heater, preferably 5 to 10 percent of the overall length of the tubular heater, and more preferably about 8 percent of the overall length of the tubular heater. One or both flared or funnel-shaped end portions of the tubular heater may be disposed at an angle of 30 to 60 degrees, 40 to 50 degrees, or about 45 degrees relative to the longitudinal axis of the tubular heater or heater assembly.

[0035] Advantageously, the flared or funnel-shaped section of the tubular heater is a convenient way of providing a tubular heater with a diameter at one or both ends that is larger than the diameter of the tubular heater in the region between the two ends of the tubular heater. Furthermore, the flared or funnel-shaped section of the tubular heater provides a smooth transition between the larger and smaller diameters, which helps to aid in the insertion of the aerosol-generating article into the tubular heater. In addition, the flared or funnel-shaped section of the tubular heater provides improved sealing of the airflow path.

[0036] In an arrangement in which the tubular heater has a flared or funnel-shaped end portion and the first and second sealing elements comprise opposing end sections of the tubular heater, the first and second sealing elements may comprise an extended section at each end of the tubular heater extending in a direction parallel to the longitudinal axis of the tubular heater. Each extended section of the tubular heater may have a length of 1 to 2 millimeters, and preferably about 1.5 mm. The length of the extended section may be 3.5 to 15 percent of the overall length of the tubular heater, preferably 7 to 12 percent of the overall length of the tubular heater, and more preferably about 9 percent of the overall length of the tubular heater.

[0037] The tubular heater 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.

[0038] 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 may be disposed around or surround the exterior surface of the tubular heater. The electric heating element may be disposed around or surround the interior surface of the tubular heater. The electric heating element may be part of or integral with the tubular heater.

[0039] The electric heating element may comprise an electrically resistive material. Suitable electrically resistive materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide), carbon, graphite, metals, alloys, and composites made of ceramic and metallic materials. Such composites may comprise doped or undoped ceramics. 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-, cobalt-, chromium-, aluminum-, titanium-, zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, gold-, and iron-containing alloys, as well as nickel-, iron-, cobalt-, and 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 optionally 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.

[0040] One or more heating elements may be formed using a metal or metal alloy having a well-defined relationship between temperature and resistivity, which may be used to both heat the heating element and monitor the temperature of the heating element during operation.

[0041] 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.

[0042] The heater assembly may comprise a flexible heating element disposed about or surrounding the exterior surface of the tubular heater, and the flexible heating element may have a length substantially equal to the length of the aerosol-forming substrate provided in the aerosol-generating article.

[0043] The tubular heater may be configured to receive at least a portion of the aerosol-generating article (as defined below).

[0044] According to an embodiment of the present disclosure, there is provided an aerosol generating device, which may include a heater assembly according to any of the heater assemblies described above, and which may include a power source for supplying power to the heater assembly.

[0045] 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 supply for supplying power to the heater assembly.

[0046] 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 battery, a lithium-iron-phosphate battery, or a lithium polymer battery.

[0047] Preferably, the aerosol generating device is a handheld aerosol generating device that is comfortable for a user to hold between the fingers of one hand.

[0048] The aerosol generating device 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, or an application specific integrated chip (ASIC) or other electronic circuit capable of providing control. The control circuit may include additional 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 activation of the device, or may be supplied intermittently (such as with each puff). Power may be supplied to the heater assembly in the form of current pulses, for example, by pulse width modulation.

[0049] The aerosol generating device may include a device housing. The device housing may house a heater assembly, a power source, 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 to allow insertion of the aerosol-generating article into the tubular heater. 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.

[0050] 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. Preferably, the material is lightweight and not brittle.

[0051] According to one embodiment of the present disclosure, there is provided an aerosol-generating system, which may comprise an aerosol-generating device according to any of the aerosol-generating devices described above, or may comprise an aerosol-generating article comprising an aerosol-forming substrate.

[0052] According to one embodiment of the present disclosure, there is provided an aerosol-generating system comprising an aerosol-generating device according to any of the aerosol-generating devices described above, and an aerosol-generating article comprising an aerosol-forming substrate.

[0053] As used herein, the term "aerosol-generating article" refers to an article that includes an aerosol-forming substrate that, when heated in an aerosol-generating device, emits a volatile compound capable of forming an aerosol. 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.

[0054] 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.

[0055] 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. Further, the diameter of the aerosol-forming substrate may be approximately 5 mm to approximately 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 approximately 7 mm long, but may also have a length of approximately 5 mm to approximately 12 mm.

[0056] The terms "upstream," "downstream," "proximal," and "distal" are used to describe the relative positions of components or portions of components of aerosol-generating devices and aerosol-generating articles. Aerosol-generating articles and devices according to the present disclosure have a proximal end through which aerosol exits 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 breathes 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 refer to the direction of travel of the aerosol through the aerosol-generating article or aerosol-generating device when the user breathes 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.

[0057] 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 also 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 separator between the aerosol-forming substrate and the filter plug. The separator may be approximately 21 mm or approximately 26 mm, but may also be in the range of approximately 5 mm to approximately 28 mm. The separator may be provided by a hollow tube. The hollow tube may be made of cardboard or cellulose acetate.

[0058] 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 containing volatile tobacco flavor 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.

[0059] 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, shreds, 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.

[0060] 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. A homogenized tobacco material sheet may be formed by agglomerating particulate tobacco obtained by grinding or otherwise comminuted one or both of tobacco lamina and tobacco stem. 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 exogenous 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.

[0061] 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. Preferably, when the aerosol-generating article is assembled, the substantially parallel ridges or corrugations extend 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.

[0062] 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 the solid substrate deposited on its inner surface, 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, nonwoven carbon fiber mat, low-mass open-mesh metal screen, or perforated metal foil, or any other thermally stable polymeric matrix.

[0063] 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, may be deposited in a pattern to provide a non-uniform flavor delivery during use.

[0064] Although reference has been made above to solid aerosol-forming substrates, 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. When a liquid aerosol-forming substrate is provided, the aerosol-generating device preferably comprises a means for retaining a 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, such as a 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-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 capsule shell preferably melts upon heating and releases the liquid aerosol-forming substrate into the porous carrier material. The capsule may optionally contain a solid in combination with the liquid.

[0065] 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.

[0066] Features described with respect to one of the above embodiments may equally be applied to other embodiments of the present disclosure. [Brief explanation of the drawings]

[0067] [Figure 1] FIG. 1 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. [Figure 2] FIG. 2 is a cross-sectional view of a portion of an aerosol generating device having a heater assembly according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is an enlarged schematic cross-sectional view of the sealing arrangement labeled A in FIG. [Figure 4] FIG. 4 is a cross-sectional view of a heater assembly according to another embodiment of the present disclosure. [Figure 5] FIG. 5 is an enlarged schematic cross-sectional view of the sealing arrangement labeled E in FIG. [Figure 6] FIG. 6 is a side view of an exemplary tubular heater for use in a heater assembly according to the present disclosure. [Figure 7] FIG. 7 is a cross-sectional view of a heater assembly according to another embodiment of the present disclosure. [Figure 8] FIG. 8 is a side view of another exemplary tubular heater for use in a heater assembly according to the present disclosure. [Figure 9] FIG. 9 is a cross-sectional view of a heater assembly according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0068] The present 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 described above, for example, with any one or more features of other examples, embodiments, or aspects described herein.

[0069] Example 1: A heater assembly for an aerosol-generating device, comprising: a heating chamber for heating an aerosol-forming substrate; an air inlet; and an aerosol outlet, wherein an airflow path extends through the heater assembly from the air inlet to the aerosol outlet, the airflow path passing through the heating chamber.

[0070] Example 2: The heater assembly according to example 1, further comprising a first heater casing, the first heater casing comprising an air inlet.

[0071] Example 3: A heater assembly according to either Example 1 or Example 2, further comprising a second heater casing, the second heater casing comprising an aerosol outlet.

[0072] Example 4: The heater assembly according to any of Examples 1-3, further comprising a first sealing element configured to seal the first heater casing to the heating chamber.

[0073] Example 5: The heater assembly according to any of Examples 1-4, further comprising a second sealing element configured to seal the second heater casing to the heating chamber.

[0074] Example 6: A heater assembly according to Example 5, wherein the first sealing element and the second sealing element are separated from the airflow path.

[0075] Example 7: A heater assembly according to any of Examples 3-6, wherein the airflow path passes through the first heater casing, the heating chamber, and the second heater casing.

[0076] Example 8: The heater assembly according to any of Examples 4-7, wherein the first sealing element comprises an annular seal and is disposed between the inner surface of the first heater casing and the outer surface of the heating chamber.

[0077] Example 9: The heater assembly according to any of Examples 5-8, wherein the second sealing element comprises an annular seal and is disposed between the inner surface of the second heater casing and the outer surface of the heating chamber.

[0078] Example 10: A heater assembly according to any of Examples 5-9, wherein at least one of the first sealing element and the second sealing element is disposed within a groove or recess formed in an inner surface of one of the first heater casing and the second heater casing, respectively.

[0079] Example 11: A heater assembly according to any of Examples 2-10, wherein the first heater casing comprises a holder for holding the heating chamber, and the airflow path passes through the holder.

[0080] Example 12: The heater assembly according to Example 1, wherein a first sealing element is disposed between the holder and the outer surface of the heating chamber.

[0081] Example 13: A heater assembly according to Example 5, wherein the first and second sealing elements comprise opposite end sections of the heating chamber, the opposite end sections being secured in sealing engagement against the inner surfaces of the first and second heater casings.

[0082] Example 14: A heater assembly according to Example 13, wherein the opposing end sections of the heating chamber are secured in sealing engagement within grooves or recesses formed in the inner surfaces of the first heater casing and the second heater casing.

[0083] Example 15: A heater assembly according to Example 13, wherein the opposing end sections of the heating chamber are embedded within the inner surfaces of the first heater casing and the second heater casing.

[0084] Example 16: A heater assembly according to any of Examples 13-15, wherein the opposite end section extends in a direction parallel to the longitudinal axis of the heating chamber for a length between 5 percent and 15 percent of the overall length of the heating chamber.

[0085] Example 17: A heater assembly according to Example 13, wherein the opposing end section of the heating chamber has a surface finish with an ISO roughness value within the range of N9 to N12.

[0086] Example 18: The heater assembly according to any of Examples 13-17, further comprising a third sealing element configured to further seal the first heater casing to the heating chamber.

[0087] Example 19: The heater assembly according to any of Examples 13-18, further comprising a fourth sealing element configured to further seal the second heater casing to the heating chamber.

[0088] Example 20: The heater assembly according to either Example 18 or Example 19, wherein the third sealing element comprises an annular seal and is disposed between the inner surface of the first heater casing and the outer surface of the heating chamber.

[0089] Example 21: The heater assembly according to any of Examples 18-20, wherein the fourth sealing element comprises an annular seal and is disposed between the inner surface of the second heater casing and the outer surface of the heating chamber.

[0090] Example 22: A heater assembly according to any of Examples 3-21, wherein the heating chamber is surrounded by a first heater casing and a second heater casing.

[0091] Example 23: The heater assembly according to any of Examples 3-21, further comprising a heater sleeve surrounding at least a portion of the heating chamber, the heater sleeve being disposed between the first heater casing and the second heater casing.

[0092] Example 24: A heater assembly according to Example 23, wherein the first sealing element engages the inner surface of the first heater casing, the outer surface of the heating chamber, and the inner surface or end surface of the heater sleeve.

[0093] Example 25: A heater assembly according to Example 23 or Example 24, wherein the second sealing element engages the inner surface of the second heater casing, the outer surface of the heating chamber, and the inner surface or end surface of the heater sleeve.

[0094] Example 26: A heater assembly according to any of Examples 1-25, wherein the diameter of the heating chamber at each end of the heating chamber is greater than the diameter of the heating chamber in the region between the two ends of the heating chamber.

[0095] Example 27: A heater assembly according to Example 26, wherein a portion of each end of the heating chamber is flared or funnel-shaped.

[0096] Example 28: A heater assembly according to Example 27, wherein the axial length of the flared or funnel-shaped end of the heating chamber is between 5 percent and 15 percent of the overall length of the heating chamber.

[0097] Example 29: A heater assembly according to any of Examples 1-28, wherein the heating chamber comprises a tubular heater.

[0098] Example 30: An aerosol generating device comprising a heater assembly according to any of Examples 1-29 and a power supply for supplying electrical power to the heater assembly.

[0099] Example 31: An aerosol-generating system comprising an aerosol-generating device according to Example 30 and an aerosol-generating article comprising an aerosol-forming substrate.

[0100] The embodiments will now be further described with reference to the figures.

[0101] Referring to Figure 1, this shows a schematic cross-sectional view of the interior of an aerosol generating device 100 and an aerosol-generating article 200 housed within the aerosol generating device 100. The aerosol generating device 100 and the aerosol-generating article 200 together form an aerosol generation system. In Figure 1, the aerosol generating device 100 is shown in a simplified manner. Specifically, 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.

[0102] The aerosol-generating device 100 comprises a housing 102 that houses a heater assembly 10, a power supply 103, and a control circuit 105. The heater assembly 10 comprises a first heater casing 12, a second heater casing 14, and a tubular heater 16 for heating an aerosol-forming substrate. The tubular heater 16 defines a cavity for at least partially receiving a portion of the aerosol-generating article 200 and has a flexible heating element (not shown) disposed around its outer surface for heating the tubular heater 16 and, in turn, the aerosol-generating article 200. The power supply 103 comprises 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 (not shown) and controls the supply of electrical energy from the power supply 103 to the heating element to regulate the temperature of the heating element.

[0103] The first heater casing 12 is attached to the second heater casing 14 and together surround or enclose the tubular heater 16 to prevent aerosol generated within the tubular heater 16 from leaking into the aerosol generation device 100. The heater assembly 10 further comprises a first sealing element (shown here in FIG. 1 ) configured to seal the first heater casing 12 to the tubular heater 16 and a second sealing element (not shown in FIG. 1 ) configured to seal the second heater casing 14 to the tubular heater 16. The first and second sealing elements serve to further prevent aerosol leakage from the tubular heater 16 into the aerosol generation device 100, and various sealing arrangements are discussed in more detail below.

[0104] The first heater casing 12 comprises an air channel section 12a and a support section 12b. The air channel section 12a extends parallel to the longitudinal axis of the aerosol generation device 100 from the distal end of the aerosol generation device 100 to the support section 12b. The support section 12b supports the tubular heater 16 and is configured to be attached to the second heater casing 14. An air inlet 18 is disposed at the distal end of the air channel section 12a of the first heater casing 12. The air inlet 18 is connected to an opening 106 formed in the distal end of the housing 102. Air can enter the aerosol generation device 10 through the opening 106 and the air inlet 18 and flow to the tubular heater 16 via the air channel section 12a.

[0105] The aerosol outlet 20 is disposed at the proximal end of the second heater casing 14. The aerosol outlet 20 is connected to an opening 104 formed in the proximal end of the housing 102. The opening 104 is also connected to the interior of the tubular heater 16, and the aerosol-generating article 200 can be received into the tubular heater 16 through the opening 104. The aerosol-generating article 200 is longer than the cavity partially defined by the tubular heater 16 inside the aerosol-generating device 100, and therefore the proximal or mouth end of the aerosol-generating article 200 protrudes from the aerosol-generating device 100 when the aerosol-generating article 200 is fully inserted.

[0106] An airflow path (indicated in FIG. 1 by arrows 22) extends through the heater assembly 10 from the air inlet 18 to the aerosol outlet 20, passing through the first heater casing 12, the tubular heater 16, and the second heater casing 14. The aerosol exits the heater assembly 10 via the aerosol outlet 20, which is connected to an opening 104 in the housing 102. However, it will be appreciated that when an aerosol-generating article is received within the aerosol-generating device 100, in use, the aerosol exits the heater assembly 10 and the aerosol-generating device 100 primarily via the aerosol-generating article 200.

[0107] In this embodiment, 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 aforementioned components of the aerosol-generating article 100 is a substantially cylindrical element, each having substantially the same diameter. The components are arranged sequentially in abutting coaxial alignment 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 sheets of crimped 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. The aerosol-forming substrate 204 is disposed within the aerosol-generating article 200 such that the aerosol-forming substrate 204 is located within the tubular heater 16 for heating the aerosol-forming substrate 204 when the aerosol-generating article 200 is fully inserted into the aerosol-generating device 100. Of course, other aerosol-generating articles having different components or different arrangements of components can also be used.

[0108] 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 remaining battery power, heating status, and error messages.

[0109] During use, a user inserts the aerosol-generating article 200 into the aerosol-generating device 100, as shown in FIG. 1 . 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 circuit 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 tubular heater 16. During the heating cycle, the heating element heats the tubular heater 16 to a predefined temperature or to a predefined range of temperatures according to a temperature profile. The heating cycle may last approximately six minutes. Heat from the tubular heater 16 is transferred to the aerosol-forming substrate 204, which releases volatile compounds from the aerosol-forming substrate 204. The volatile compounds form an aerosol within 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 their lips and puffs or inhales on the mouthpiece filter 208. This creates a pressure drop within the aerosol-generating article 200, which is in fluid communication with the air inlet 18 and opening 106 of the aerosol-generating device 100 via the air channel section 12a of the first heater casing 12. The pressure drop causes air to be drawn into the aerosol-generating device 100 via the air inlet 18 and flow through the air channel section 12a to the aerosol-generating article 200. The air passes through the aerosol-generating article 200 entraining the aerosol generated from the aerosol-forming substrate 204, which is then drawn through the mouthpiece filter 208 into the user's mouth.

[0110] Figure 2 is a cross-sectional view of a portion of an aerosol generating device 300 having a heater assembly 310 according to an embodiment of the present disclosure. The aerosol generating device 300 of Figure 2 has a general configuration similar to that of the aerosol generating device 100 of Figure 1. The heater assembly 310 includes a first heater casing 312, a second heater casing 314, and a tubular heater 316 for heating an aerosol-forming substrate received within the tubular heater 316. The tubular heater 316 has a flexible heating element 317 disposed around its outer surface for heating the tubular heater 316.

[0111] In the exemplary heater assembly 310 of FIG. 2 , the first heater casing includes a tube holder 319 for holding the tubular heater 316. The tube holder 319 serves to position the tubular heater 316 within the heater assembly 310. A holder air channel 321 extends axially through the tube holder 319, allowing air to flow through the tube holder 319. The first heater casing 312 is attached to the second heater casing 314, and together the first heater casing 312 and the second heater casing 314 surround the tubular heater 316 and the tube holder 319 to prevent aerosol generated within the tubular heater 316 from leaking into the aerosol generation device 100. The wall of the second heater casing 314 is radially spaced from the tubular heater 316 to define a gap 323 around the tubular heater 316. The void 323 helps to insulate the tubular heater 316, which helps to reduce heat loss from the tubular heater 316 and also helps to reduce heat transfer to the outside of the heater assembly 310 and aerosol generating device 300.

[0112] The first heater casing 312 includes an air channel section 312a and a support section 312b. The support section 312b is configured to attach to the second heater casing 314. An air inlet (not shown) is disposed at the distal end of the air channel section 312a. An aerosol outlet 320 is disposed at the proximal end of the second heater casing 314 and is connected to an opening 304 formed at the proximal end of the housing 302 of the aerosol generating device 300. An aerosol-generating article (not shown) can be received through the opening 304 and into the tubular heater 316. An airflow path (indicated by multiple arrows 322 in FIG. 2 ) extends from the air inlet (not shown) to the aerosol outlet 320 through the heater assembly 310 and passes through the first heater casing 312, including the tube holder 319, the tubular heater 316, and the second heater casing 314.

[0113] Heater assembly 310 further comprises a first sealing element 326 that seals tubular heater 316 to tube holder 319 of first heater casing 312. First sealing element 326 comprises an O-ring that surrounds tubular heater 316 near its distal end. The O-ring contacts the outer surface of tubular heater 316 and tube holder 319 of first heater casing 312 to provide a seal between these two components that inhibits leakage of aerosol from tubular heater 316 into cavity 323 surrounding tubular heater 316 or other portions of aerosol generation device 300. The area sealed by the first sealing element is indicated by circles C and D in FIG. 2 .

[0114] The heater assembly 310 further comprises a second sealing element 324 that seals the tubular heater 316 to the second heater casing 314. The second sealing element 324 comprises an O-ring that surrounds the tubular heater 316 near its proximal end. The O-ring contacts the outer surface of the tubular heater 316 and the inner surface of the second heater casing 314 to provide a seal between these two components that inhibits leakage of aerosol from the tubular heater 316 into a void 323 surrounding the tubular heater 316 or other portions of the aerosol generation device 300. The area sealed by the second sealing element is indicated by circles A and B in FIG. 2 .

[0115] The O-rings of first sealing element 326 and second sealing element 324 are preferably formed from a perfluoroelastomer such as FFKM due to its elastic deformability, temperature resistance, and low toxicity. A suitable O-ring is a Kalrez™ O-ring manufactured by DuPont. However, other suitable O-rings and materials may be used.

[0116] Figure 3 is an enlarged schematic cross-sectional view of the enclosed area labeled A in Figure 2 that is sealed by second sealing element 324. Tubular heater 316 has a flared proximal end 316a, as described in more detail below with respect to Figure 6. The inner surface of second heater casing 314 includes a recess or groove 328 for receiving flared proximal end 316a of tubular heater 316. Second sealing element 324 is also positioned within groove 328 and engages the inner surface of groove 328 and the outer surface of tubular heater 316 to inhibit leakage of aerosol from tubular heater 316 into gap 323 between tubular heater 316 and second heater casing 314. The second sealing element 324 is positioned on the opposite side of the tubular heater 316 from where the airflow path 322 passes through the tubular heater 316, such that the wall of the tubular heater 316 acts as a physical barrier between the second sealing element 324 and the airflow path, keeping the second sealing element separated from the airflow path 322.

[0117] As described above with respect to Figure 2, the second sealing element comprises an O-ring and surrounds the outer surface of the tubular heater 316 in the region of the flared proximal end 316a, so that a mirror image of Figure 3 can be seen in the boxed area labeled B in Figure 2. A groove arrangement similar to that shown in Figure 3 is also provided in the tube holder 319 of the first heater casing 312 and at the distal end of the tubular heater 316, i.e., in the boxed areas labeled C and D in Figure 2.

[0118] FIG. 4 is a cross-sectional view of a heater assembly 410 according to another embodiment of the present disclosure. The heater assembly 410 of FIG. 4 has a general configuration similar to the heater assemblies 10 and 310 of FIGS. 1 and 2, respectively. The heater assembly 410 includes a first heater casing 412, a second heater casing 414, and a tubular heater 416 for heating an aerosol-forming substrate received within the tubular heater 416. However, in the embodiment of FIG. 4, the first heater casing 412 is not directly connected to the second heater casing 414, but instead a heater sleeve 430 is disposed between the first heater casing 412 and the second heater casing 414. The heater sleeve 430 circumferentially surrounds substantially the entire length of the tubular heater 416, except for the two ends of the tubular heater 416 that are disposed within the first heater casing 412 and the second heater casing 414.

[0119] Additionally, in the embodiment of Figure 4, the tubular heater 416 is supported directly on the first heater casing 412, although a tube holder can be used if desired, as in the embodiment of Figure 2. An airflow path (indicated by arrows 422 in Figure 4) extends through the heater assembly 410 from an air inlet 418 at the distal end of the first heater casing 412 to an aerosol outlet 420 at the proximal end of the second heater casing 414, and passes through the first heater casing 412, the tubular heater 416, and the second heater casing 414.

[0120] The heater assembly 410 further comprises a first sealing element 426 that seals the tubular heater 416 to the first heater casing 412 and the heater sleeve 430. The first sealing element 426 comprises an O-ring that surrounds the tubular heater 416 near its distal end. The O-ring contacts the outer surface of the tubular heater 416, the inner surface of the first heater casing 412, and the distal end surface of the heater sleeve 430 to provide a seal between these components that inhibits leakage of aerosol from the heater assembly 410 into the surrounding portions of the aerosol generation device 300.

[0121] The heater assembly 410 further comprises a second sealing element 424 that seals the tubular heater 416 to the second heater casing 414 and the heater sleeve 430. The second sealing element 324 comprises an O-ring that surrounds the tubular heater 416 near its proximal end. The O-ring contacts the outer surface of the tubular heater 416, the inner surface of the second heater casing 414, and the proximal end surface of the heater sleeve 430 to provide a seal between these components that inhibits leakage of aerosol from the heater assembly 410 into the surroundings of the aerosol generation device 300.

[0122] The same materials used for the O-rings of first sealing element 326 and second sealing element 324 in FIG. 2 can be used for the O-rings of first sealing element 426 and second sealing element 424 in FIG.

[0123] Figure 5 is an enlarged schematic cross-sectional view of the enclosed area labeled E in Figure 4 that is sealed by second sealing element 424. As in the embodiment of Figure 3, tubular heater 416 in Figure 5 has a flared proximal end 416a. The inner surface of second heater casing 414 and the proximal end surface of heater sleeve 430 define a recess or groove 428 for receiving flared proximal end 416a of tubular heater 416. Second sealing element 424 is also positioned within groove 428 and engages the inner surface of groove 428 and the outer surface of tubular heater 416 to inhibit leakage of aerosol from tubular heater 416 into gap 423 between tubular heater 416 and heater sleeve 430. The second sealing element 424 is positioned on the opposite side of the tubular heater 416 from where the airflow path 422 passes through the tubular heater 416, such that the wall of the tubular heater 416 acts as a physical barrier between the second sealing element 424 and the airflow path 422, keeping the second sealing element 424 separated from the airflow path 422. A groove arrangement similar to that shown in Figure 5 is also provided in the first heater casing 412 at the distal end of the tubular heater 416.

[0124] FIG. 6 is a side view of an exemplary tubular heater 16 for use in a heater assembly according to the present disclosure. The tubular heater 16 comprises a stainless steel tube having a circular cross-section. A hollow interior space within the tubular heater 16 has an inner diameter substantially corresponding to the outer diameter of an aerosol-generating article (not shown) so that the tubular heater 16 can receive the aerosol-generating article within the interior space. Portions 16a of the tubular heater 16 at each end of the tubular heater 16 flare outward to form a funnel shape at each end of the tubular heater 16. The flared portions 16a each have a length l1, and the percentage of the overall length l of the tubular heater 16 made up by each flared portion length l1 may be in the range of 5 to 15 percent. Each flared end portion 16a of the tubular heater 16 forms an angle θ with the longitudinal axis of the tubular heater 16. In this example, θ is approximately 45 degrees, although other suitable angles may be used. As a result of the flared end portions 16a, the outer diameter D at the two ends of the tubular heater 16 is greater than the outer diameter d of the tubular heater 16 between the two flared end portions 16a.

[0125] A portion 16b of the tubular heater 16 between the two flared end portions 16a has straight sides parallel to the longitudinal axis of the tubular heater 16. The straight portion 16b of the tubular heater 16 has a length that substantially corresponds to the length of an aerosol-forming substrate provided in an aerosol-generating article configured to be received within the tubular heater 16.

[0126] 7 is a cross-sectional view of a heater assembly 510 according to another embodiment of the present disclosure. The heater assembly 510 includes a first heater casing 512, a second heater casing 514, and a tubular heater 516 for heating an aerosol-forming substrate received within the tubular heater 516. The tubular heater 516 is disposed between the first heater casing 512 and the second heater casing 514. An airflow path (indicated by multiple arrows 522 in FIG. 7 ) extends through the heater assembly 510 from an air inlet 518 at the distal end of the first heater casing 512 to an aerosol outlet 520 at the proximal end of the second heater casing 514, and passes through the first heater casing 512, the tubular heater 516, and the second heater casing 514.

[0127] 2 and 4, the heater assembly 510 of FIG. 7 does not use O-rings as sealing elements to seal the first heater casing 512 and the second heater casing 514 to the tubular heater 516. Instead, in the embodiment of FIG. 7, the first sealing element 526 and the second sealing element 524 comprise opposing end sections 516c of the tubular heater 516, which are secured in sealing engagement with the inner surfaces 512a and 514a of the first heater casing 512 and the second heater casing 514, respectively.

[0128] The first and second sealing elements 526, 524 may be formed by securing the end section 516c of the tubular heater 516 in sealing engagement within grooves or trenches 512b, 514b extending circumferentially around the inner surface 512a of the first heater casing 512 and the inner surface 514a of the second heater casing 514, respectively. Alternatively, the first and second sealing elements 524, 524 may be provided by forming the first and second heater casings 512, 514 around the end section 516c of the tubular heater 516, or by driving the end section 516c of the tubular heater 516 into the first and second heater casings 512, 514 so that the end section 516c is embedded in the inner surface 512a of the first heater casing 512 and the inner surface 514a of the second heater casing 514, respectively. The sealing engagement of the first sealing element 526 and the second sealing element 524 can be achieved by one or more of the following processes: insert molding, overmolding, hot melting, radio frequency welding, and ultrasonic welding. Of course, other suitable processes may also be used.

[0129] End section 516c of tubular heater 516 is elongated so that it can extend into grooves or trenches 512b and 514b or into inner surface 512a of first heater casing 512 and inner surface 514a of second heater casing 514, respectively, while maintaining the same length of tubular heater 516 between first heater casing 512 and second heater casing 514. The surface of end section 516c of tubular heater 516 is roughened to have a surface finish with an ISO roughness value in the range of N9 to N12 to help retain end portion 516c within grooves or trenches 512b and 514b or to help bond material of first heater casing 512 and second heater casing 514 to end portion 516c.

[0130] 7, the two opposing end sections 516c are sealed within the first heater casing 512 and the second heater casing 514. The sealing engagement of the opposing end sections 516c of the tubular heater 516 with the grooves or trenches 512b and 514b or the interior surfaces of the first heater casing 512 and the second heater casing 514 serves to seal the airflow path 522 and protect the opposing end sections 516c. Additionally, the material of the first heater casing 512 and the second heater casing 514 surrounding the end sections 516c acts as a physical barrier between the end sections 516c and the airflow path.

[0131] FIG. 8 is a side view of the tubular heater 516 from the heater assembly 510 of FIG. 7, showing the tubular heater 516 in more detail. The shape and size of the tubular heater 516 of FIG. 8 is substantially the same as the tubular heater 16 of FIG. 6, except that the tubular heater 516 of FIG. 8 has extended end sections 516c. The tubular heater 516 comprises a stainless steel tube having a circular cross-section. A portion 516a of the tubular heater 516 near each end of the tubular heater 516 flares outward to form a funnel shape at each end of the tubular heater 516. The flared end portions 516a of the tubular heater 516 each form an angle β with the longitudinal axis of the tubular heater 516. In this example, β is approximately 45 degrees, although other suitable angles may be used. As a result of the flared end portions 516a, the outer diameter D at the two ends of the tubular heater 516 is greater than the outer diameter d of the tubular heater 516 between the two flared end portions 516a. The two end sections 516c of the tubular heater 516 are elongated and extend a distance l2 in a direction parallel to the longitudinal axis of the tubular heater 516. The percentage of the overall length l of the tubular heater 516 made up by each end section length l2 may be in the range of 5 to 15 percent. As described above, the surface of the end section 516c of the tubular heater 516 is roughened to have a surface finish with an ISO roughness value in the range of N9 to N12.

[0132] Figure 9 is a cross-sectional view of a heater assembly 610 according to another embodiment of the present disclosure. The heater assembly 610 of Figure 9 is a combination of the sealing arrangements provided in the heater assembly 410 of Figure 4 and the heater assembly 510 of Figure 7, respectively. The heater assembly 610 includes a first heater casing 612, a second heater casing 614, and a tubular heater 616 for heating an aerosol-forming substrate received within the tubular heater 616. The tubular heater 616 is disposed between the inner surfaces of the first heater casing 612 and the second heater casing 614. A heater sleeve 630 is disposed between the inner surfaces of the first heater casing 612 and the second heater casing 614. The heater sleeve 630 circumferentially surrounds substantially the entire length of the tubular heater 616, except for the two ends of the tubular heater 616 that are disposed within the first heater casing 612 and the second heater casing 614. An airflow path (indicated by multiple arrows 622 in FIG. 9 ) extends through the heater assembly 610 from the air inlet 618 at the distal end of the first heater casing 612 to the aerosol outlet 620 at the proximal end of the second heater casing 614, and passes through the first heater casing 612, the tubular heater 616, and the second heater casing 614.

[0133] Similar to heater assembly 510 of FIG. 7, heater assembly 610 of FIG. 9 has first and second sealing elements 626, 624 with opposite end sections 616c of tubular heater 616 secured in sealing engagement with inner surfaces 612a, 614a of first and second heater casings 612, 614, respectively.

[0134] 9 further includes a third sealing element 632 and a fourth sealing element 634 for sealing the tubular heater 616 to the first heater casing 612 and heater sleeve 630, and for sealing the tubular heater 616 to the second heater casing 614 and heater sleeve 630, respectively. The third sealing element 632 and the fourth sealing element 634 are the same as the first sealing element 426 and the second sealing element 424 of the heater assembly 410 of FIG.

[0135] The third sealing element 632 comprises an O-ring that surrounds the tubular heater 616 near its distal end. The O-ring contacts the outer surface of the tubular heater 616, the inner surface of the first heater casing 612, and the distal end surface of the heater sleeve 630 to provide a seal between these components that inhibits leakage of aerosol from the heater assembly 610 into the surrounding portion of the aerosol generation device (not shown).

[0136] The fourth sealing element 634 comprises an O-ring that surrounds the tubular heater 616 near its proximal end. The O-ring contacts the outer surface of the tubular heater 616, the inner surface of the second heater casing 614, and the proximal end surface of the heater sleeve 630 to provide a seal between these components that inhibits leakage of aerosol from the heater assembly 610 into the surroundings of the aerosol-generating device (not shown).

[0137] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like are understood to be modified in all instances by the term "about." Also, all ranges include the disclosed maximum and minimum points, 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%) of A. Within this context, the number A may be considered to include values that are within the common standard error for measurement of the property that it modifies. In some instances, as used in the appended claims, the number A may deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, 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, comprising: a first heater casing having an air intake; a second heater casing having an aerosol outlet; a tubular heater for heating the aerosol-forming substrate; an airflow path extending through the heater assembly from the air inlet to the aerosol outlet, the airflow path passing through the first heater casing, the tubular heater, and the second heater casing; a first sealing element configured to seal the first heater casing against the tubular heater; a second sealing element configured to seal the second heater casing against the tubular heater; a heater assembly, wherein the first sealing element and the second sealing element are separated from the airflow path;

2. The heater assembly of claim 1 , wherein the first sealing element comprises an annular seal and is disposed between an inner surface of the first heater casing and an outer surface of the tubular heater.

3. 3. The heater assembly of claim 1, wherein the second sealing element comprises an annular seal and is disposed between an inner surface of the second heater casing and an outer surface of the tubular heater.

4. 2. The heater assembly of claim 1, wherein at least one of the first sealing element and the second sealing element is disposed within a groove or recess formed in an inner surface of one of the first heater casing and the second heater casing, respectively.

5. The heater assembly of claim 1 , wherein the first heater casing includes a tube holder for holding the tubular heater, and the airflow path passes through the tube holder.

6. The heater assembly of claim 5 , wherein the first sealing element is disposed between the tube holder and an outer surface of the tubular heater.

7. 2. The heater assembly of claim 1, wherein the first and second sealing elements comprise opposite end sections of the tubular heater, the opposite end sections being secured in sealing engagement against the inner surfaces of the first and second heater casings.

8. 8. The heater assembly of claim 7, wherein the opposed end sections of the tubular heater are secured in sealing engagement within grooves or recesses formed in the inner surfaces of the first and second heater casings.

9. The heater assembly of claim 7 , wherein the opposed end sections of the tubular heater are embedded within the interior surfaces of the first and second heater casings.

10. 8. The heater assembly of claim 7, wherein the opposed end sections of the tubular heater have a surface finish with an ISO roughness value in the range of N9 to N12.

11. a third sealing element configured to further seal the first heater casing against the tubular heater; 8. The heater assembly of claim 7, further comprising: a fourth sealing element configured to further seal the second heater casing to the tubular heater.

12. The heater assembly of claim 11 , wherein the third sealing element comprises an annular seal and is disposed between an inner surface of the first heater casing and an outer surface of the tubular heater.

13. 13. The heater assembly of claim 11 or 12, wherein the fourth sealing element comprises an annular seal and is disposed between an inner surface of the second heater casing and an outer surface of the tubular heater.

14. The heater assembly of claim 1 , wherein the tubular heater is surrounded by a first heater casing and a second heater casing.

15. 2. The heater assembly of claim 1, further comprising a heater sleeve surrounding at least a portion of the tubular heater, the heater sleeve being disposed between the first heater casing and the second heater casing.

16. 16. The heater assembly of claim 15, wherein the first sealing element engages an inner surface of the first heater casing, an outer surface of the tubular heater, and an inner surface or an end surface of the heater sleeve.

17. 17. The heater assembly of claim 15 or 16, wherein the second sealing element engages an inner surface of the second heater casing, an outer surface of the tubular heater, and an inner surface or an end surface of the heater sleeve.

18. 2. The heater assembly of claim 1, wherein the diameter of the tubular heater at each end of the tubular heater is greater than the diameter of the tubular heater in a region between the two ends of the tubular heater.

19. 20. The heater assembly of claim 18, wherein a portion of each end of the tubular heater is flared or funnel shaped.

20. An aerosol generating device, comprising: The heater assembly of claim 1; a power supply for supplying power to the heater assembly.

21. 1. An aerosol generating system comprising: The aerosol generating device according to claim 20; an aerosol-generating article comprising an aerosol-forming substrate.

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