RU2846171C2 - Heater unit with sealed air flow path - Google Patents

Abstract

FIELD: smoking accessories.

SUBSTANCE: invention relates to heater assembly (1) for an aerosol-generating device. To this end, heater assembly (1) comprises: first heater housing (2) comprising an air inlet; second heater housing (4) comprising aerosol outlet (10); and heating chamber (6) for heating the aerosol-forming substrate, wherein heating chamber (6) is in fluid communication with both the air inlet, and with aerosol outlet (10) with determination of air flow path through heater assembly; wherein heater unit (1) further comprises: heater attachment (8), wherein heating chamber (6) is mounted on heater attachment (8); and seal (30) for sealing the air flow path; wherein seal (30) is mounted on heater attachment (8) such that seal (30) is spaced from heating chamber (6).

EFFECT: improved sealing of unit (1) air flow path.

18 cl, 13 dwg

Description

The present invention relates to a heater unit for an aerosol generating device (for generating an aerosol). The present invention also relates to an aerosol generating device comprising a heater unit. In particular, but not exclusively, the present invention relates to a hand-held electric aerosol generating device for heating an aerosol-forming substrate to generate an aerosol and delivering the aerosol to the user's mouth. The present invention also relates to an aerosol generating system (for generating an aerosol) comprising an aerosol generating device and an aerosol-forming substrate.

Aerosol generating devices that heat an aerosol-forming substrate to produce an aerosol without burning the aerosol-forming substrate are known in the art. The aerosol-forming substrate is typically provided inside an aerosol-generating article, along with other components such as filters. The aerosol-generating article (for generating an aerosol) may be in the form of a rod for inserting the aerosol-generating article into a heating chamber of the aerosol-generating device. A heating element is typically located 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.

The heating chamber may be located within the housing of the aerosol generating device and form part of the air flow path through the aerosol generating device. It is known to provide seals around the air flow path and between the heating chamber and the housing to prevent leakage of aerosol from the air flow path to other parts of the aerosol generating device, which may cause damage to the electronic components of the device. The seals may be located in direct contact with the heating chamber and, therefore, are typically made of a heat-resistant polymer, such as silicone or polysiloxane. However, exposure of such polymer seals to heating temperatures of the heating chamber may result in the formation of unwanted by-products that may contaminate the aerosol. In addition, such heating temperatures may degrade the seals over time.

To heat the heating chamber, the aerosol generating device may comprise a flexible heating element arranged around the heating chamber. In order to allow direct contact between the seals and the heating chamber and to reduce heating of the seals, attempts have been made to remove the seals 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, by using a longer heating chamber, which increases the energy consumption of the heating chamber and reduces the efficiency of the aerosol generating device. In addition, increasing the length of the heating chamber may result in the heating chamber surrounding other components of the aerosol generating article, such as filters, which may be indirectly heated due to heat conduction through the heating chamber. Heating of the filters results in an undesirable waste of energy.

An alternative to increasing the length of the heating chamber may be to reduce the length of the heating element surrounding the heating chamber. However, this may result in a portion of the aerosol-forming substrate not being covered or surrounded by the heating element, so that the heat must travel a greater 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 wall of the heating chamber. Therefore, the portion of the aerosol-forming substrate that is not surrounded by the heating element may be heated less efficiently than the portion that is surrounded by the heating element. Consequently, the portion of the aerosol-forming substrate that is not surrounded by the heating element may have a lower temperature than the portion that is surrounded by the heating element, which may result in premature condensation of the aerosol in the cooler portion. This may result in less aerosol being delivered to the user.

Another disadvantage of using polymer seals between the heating chamber and the housing of the device is that they provide a heat conduction path that transfers heat from the heating chamber to the materials surrounding the heating chamber. This lost heat reduces the heat available to heat the aerosol-forming substrate and reduces the efficiency of the aerosol-generating device.

An additional challenge faced when sealing air flow paths within aerosol generating devices is process tolerance. Variations in component dimensions due to process tolerances can result in poor component interactions and possibly gaps through which aerosol can leak. Achieving a good seal between components typically requires strict process tolerances, which can be difficult to achieve in rapid manufacturing technologies such as injection molding.

It would be desirable to provide a heater assembly for an aerosol generating device with improved sealing of its air flow path. It would be desirable to provide a heater assembly for an aerosol generating device that is more energy efficient and improves aerosol delivery to a user. It would be desirable to provide a heater assembly for an aerosol generating device that is better able to absorb process tolerances.

According to an example of the present invention, a heater unit for an aerosol generating device is proposed. The heater unit may comprise a first heater housing. The first heater housing may comprise an air inlet. The heater unit may comprise a second heater housing. The second heater housing may comprise an aerosol outlet. The heater unit 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 air flow path through the heater unit. The heater unit may comprise a heater mount. The heating chamber may be mounted on the heater mount. The heater unit may comprise a seal for sealing the air flow path. The seal may be mounted on the heater mount. The seal may be located at a distance from the heating chamber.

According to an example of the present invention, a heater unit for an aerosol generating device is proposed. The heater unit comprises: a first heater casing comprising an air inlet; a second heater casing comprising an aerosol outlet; and a heating chamber for heating an aerosol-forming substrate, wherein the heating chamber is in fluid communication with both the air inlet and the aerosol outlet to define an air flow path through the heater unit. The heater unit further comprises a heater mount. The heating chamber is mounted on the heater mount. The heater unit further comprises a seal for sealing the air flow path. The seal is mounted on the heater mount so that it is located at a distance from the heating chamber.

One advantage of installing the seal on the heater mount rather than on the heating chamber is that contact between the seal and the heating chamber is prevented. In addition, the seal is preferably installed on the heater mount such that it is spaced or removed from the heating chamber. This distance between the heating chamber and the seal means that the seal is maintained at a lower temperature than the heating chamber and does not overheat. Since the seal is not subjected to high thermal loads, an improved seal of the air flow path through the heater assembly can be achieved.

Another advantage of installing 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 seals and the heating chamber. Any space at one or more ends of the heating chamber, such as to prevent direct contact between the heating element and the surrounding heater housings, can be significantly reduced. This means that shorter heating chambers can be used and a greater proportion of the length of the heating tube can be heated. This allows for more efficient heating of the aerosol-forming substrate.

The heater assembly of the present invention is also less susceptible to process tolerances because the seal is capable of absorbing at least a portion of the process tolerances to provide improved sealing, as discussed in more detail below.

The aerosol outlet may be an opening for placing an aerosol-generating article. The aerosol may exit from the opening through the aerosol-generating article placed in the heating chamber.

The first and second heater housings may be attached to each other. The first and second heater housings may cover the heating chamber and the heater mount. The seal may be located between the heater mount and the inner surface of one of the first and second heater housings. This arrangement provides a seal between the heater mount and one of the first and second heater housings to effectively seal at least a portion of the air flow path through the heater assembly to prevent aerosol leakage from the air flow path into the aerosol generating device.

The first and second heater casings may be attached to each other by means of a fastener. The first and second heater casings may be attached to each other by means of several fasteners. Several fasteners may be symmetrically distributed around the first and second heater casings. The fastener or several fasteners may comprise a threaded fastener, such as a bolt. The fastener or several fasteners may comprise a locking fastener.

The first and second heater housings may be radially spaced from the heating chamber and the heater mount to define a hollow air gap around the heating chamber and the heater mount. Preferably, the hollow air gap helps provide thermal insulation for the heating chamber, which helps reduce heat loss from the heating chamber and also helps reduce heat transfer to the outside of the heater assembly.

If necessary, the seal may be located between the heater mount and the inner surface of the first heater casing. Alternatively, the seal may be located between the heater mount and the inner surface of the second heater casing.

The seal may be mounted on a first side of the heater mount. The heating chamber may be mounted on a second side of the heater mount. The second side may be axially opposite to the first side. The seal may be mounted on a first end of the heater mount. The heating chamber may be mounted on a second end of the heater mount. The second end may be axially opposite to the first end. One advantage of mounting the seal on a side or end of the heater mount axially opposite to the first side or end is that the seal can apply an axial force to the heater mount, which in turn can apply an axial force to the heating chamber. Applying the axial force ensures that the heating chamber and the heater mount interact with each other to seal the air flow path in the intersection region between the heater mount and the heating chamber. In addition, the axial force is transmitted along the length of the air flow path, for example, at points where the heater mount and the heating chamber are connected to the inner surfaces of the first and second heater casings. Therefore, the seal helps to provide a seal at these connection points also to seal along the length of the air flow path and to prevent leakage of aerosol from the air flow path into the aerosol generating device.

Another advantage of installing a seal on the side of the heater mount axially opposite the first side is that the seal can help absorb process tolerances. For example, the seal can help absorb axial or longitudinal tolerances. In the context of this document, the term "axial tolerance" or "longitudinal tolerance" is used to describe process tolerances in a direction substantially parallel to the main longitudinal axis or length of the heater assembly or aerosol generating device, such as tolerances that cause components to be longer or shorter than their specified design length. Axial or longitudinal tolerances are sometimes referred to as "vertical tolerances." In addition, the seal can also help absorb tilt tolerances. In the context of this document, the term "tilt tolerance" is used to describe the allowable manufacturing tolerances that result in tilting of components relative to the major longitudinal axis or length of the heater or aerosol generating device assembly, such as where one side of a support is at a different level or axial position relative to the other side of the support, resulting in tilting of the component it supports.

The seal helps to absorb process tolerances in a variety of ways. For example, if a component, such as a heating chamber, is too short, the thickness of the seal can compensate for the shortfall in length of the heating chamber and allow the heater mount to cooperate with the heating chamber to close any gap that might otherwise occur. If a component, such as a heating chamber, is too long, the seal can be compressed to accommodate the excess length. If a point on the surface of the heater mount on which the heating chamber is mounted is located at a different level or in a different axial position relative to another point on the same surface, causing the heating chamber to tilt during installation, at least a portion of the seal can be compressed to allow the heating chamber to be properly aligned.

The heater mount may be located upstream or remotely relative to the heating chamber. The terms "distal", "upstream", "near" and "further downstream" are used to describe the relative position of the components or parts of the components of the aerosol-generating device and the aerosol-generating article. The aerosol-generating articles and devices according to the present invention have a near end through which, in use, the aerosol exits the article or device for delivery to the user, and have an opposite far end. The near end of the article and the aerosol-generating device may also be called a mouthpiece end. In use, the user draws on the near end of the aerosol-generating article to inhale the aerosol generated by the article or the aerosol-generating device. The terms "upstream" and "downstream" refer to the direction of movement of the aerosol through an aerosol-generating article or an aerosol-generating device when a user puffs on the near end of the aerosol-generating article. The near end of the aerosol-generating article is located downstream of the far end of the aerosol-generating article. The near end of the aerosol-generating article may also be referred to as the downstream end of the aerosol-generating article, and the far end of the aerosol-generating article may also be referred to as the upstream end of the aerosol-generating article.

Preferably, by locating the heater mount upstream of, or remotely relative to, the heating chamber, the amount of heated aerosol that will move from the heating chamber to the heater mount is reduced because the aerosol will tend to move in the direction of the air flow path through the heater assembly, i.e., from the heating chamber to the aerosol outlet, which is located further downstream of the heating chamber. Therefore, such an arrangement reduces heat transfer with respect to the heater mount and helps maintain a lower seal temperature than the heating chamber.

The heater mount may contain a polymer. Polymers typically have lower thermal conductivity values than the material of which the heating chamber is made, which is usually a metal or metal alloy. A heater mount containing or made of a polymer helps reduce heat transfer to the seal, maintaining a lower seal temperature than the heating chamber.

The seal may be located at a distance of at least 2 millimeters from the heating chamber. The seal may be located at a distance of at least 4 millimeters from the heating chamber. The seal may be located at a distance of approximately 6 millimeters from the heating chamber. The seal may be located at a distance of 2 millimeters to 6 millimeters from the heating chamber and preferably at a distance of 4 millimeters to 6 millimeters from the heating chamber.

The seal may be resilient. The seal may be made of any suitable material. The seal may comprise a resilient material. The seal may comprise a polymer. The seal may comprise an elastomeric polymer. The seal may comprise or be made of any suitable polymer, including, but not limited to, EPDM rubber or silicone.

The seal may be compressed when the heater assembly is assembled. The seal may be compressed between the heater mount and the first heater housing when the heater assembly is assembled.

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 approximately 70A. These Shore hardness values have been found to be soft enough to absorb longitudinal and tilt tolerances, but still hard enough to ensure that sufficient force is applied to the heater assembly to seal the air flow path and the integrity of the heater assembly.

The seal may have any suitable shape. The seal may have a shape that matches the shape of the heater mount. The seal may have a shape that matches the shape of one of the first or second heater casings. The seal may comprise a sealing 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 with two opposing flat surfaces, such as a square or rectangular cross-sectional shape.

The seal may have a thickness or uncompressed diameter of between 0.5 millimeters and 2 millimeters. The seal may have a thickness or uncompressed diameter of approximately 1 millimeter. These uncompressed thicknesses have been found to be particularly effective in absorbing longitudinal and tilt tolerances and in providing a seal to the air flow path and the integrity of the heater assembly.

The first heater housing may comprise an air flow channel. The air flow channel of the first heater housing may be in fluid communication with the air inlet. The second heater housing may comprise an air flow channel. The air flow channel of the second heater housing may be in fluid communication with the aerosol outlet. The heating chamber may comprise an air flow channel. The air flow channel of the heating chamber may extend along the entire length of the heating chamber. The heater mount may comprise an air flow channel. The air flow channel of the heater mount may extend along the entire thickness or length of the heater mount. The air flow channels of each of the first heater housing, the second heater housing, the heating chamber, and the heater mount may be in fluid communication with each other to define an air flow path through the heater assembly.

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

Preferably, providing a diameter of one or both ends of the tubular heating chamber that is 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 large process tolerances for the heating chamber and also for other components of the heater assembly. In particular, this allows for large process tolerances in the radial or transverse directions. In the context of this document, the terms "radial tolerance" or "transverse tolerance" are used to describe process tolerances in a direction substantially perpendicular to the main longitudinal axis or length of the heater assembly or aerosol generating device, for example tolerances that result in components being wider or narrower than their specified design width, or in diameters being larger or smaller than their specified design diameter. Radial or transverse tolerances are sometimes referred to as "horizontal tolerances".

Preferably, when providing a diameter of the end of the tubular heating chamber that is larger than other parts of the tubular heating chamber, the internal diameter at one or both ends of the tubular heating chamber will be larger than the internal diameter of the air flow path in other components of the heater assembly with which the tubular heating chamber interacts, such as in the second heater casing or the heater mount. This helps to avoid protruding or penetrating the end surface of the tubular heating chamber into the interior of the air flow path, which can possibly cause damage to the aerosol-generating article when it is placed in the heating chamber through the air flow path, and can leave less end surface of the tubular heating chamber to ensure sealing interaction with other components. This arrangement also allows for greater tolerances in the radial or transverse directions in other components, as described in more detail below.

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 from 1 percent to 20 percent larger, from 1 percent to 15 percent larger, from 1 percent to 12 percent larger, or from 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.

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

The internal diameter of the heating chamber may substantially correspond to, or be substantially equal to, the external diameter of the aerosol-generating article. In some embodiments, the internal diameter of the heating chamber may be slightly smaller than the external diameter of the aerosol-generating article, so that the aerosol-generating article is compressed in the heating chamber. For example, the external diameter of the aerosol-generating article may be approximately 7.4 millimeters, and the internal diameter of the heating chamber may be approximately 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 in the aerosol-generating article.

At least one end portion of the tubular heating chamber may be flared or funnel-shaped. The 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 portion of the tubular heating chamber may be from 0.5 percent to 10 percent of the total length of the tubular heating chamber, preferably from 1 percent to 5 percent of the total length of the tubular heating chamber, and more preferably approximately 3.3 percent of the total length of the tubular heating chamber.

The axial length of the flared or funnel-shaped end portion of the tubular heating chamber may be from 0.2 millimeters to 2 millimeters, preferably from 0.4 millimeters to 1 millimeter and more preferably about 0.5 mm. The flared or funnel-shaped end portion or end portions of the tubular heating chamber may be located at an angle of from 30 to 60 degrees, from 40 to 50 degrees or at an angle of about 45 degrees relative to the longitudinal axis of the heating chamber or the heater assembly. In some preferred embodiments, the flared or funnel-shaped end portion or end portions of the tubular heating chamber may be located 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 the heater assembly. Preferably, providing a flared or funnel-shaped end portion or end portions of the tubular heating chamber at an angle of less than 30 degrees relative to the longitudinal axis of the heating chamber or the heater assembly can provide optimum rigidity for the flared or funnel-shaped end portion or end portions of the tubular heating chamber in the direction of the longitudinal axis of the heating chamber or the heater assembly.

At least one end or end portion of the tubular heating chamber may have a stepped profile or be elbowed. The portion of the tubular heating chamber at both ends of the tubular heating chamber may have a stepped profile or be elbowed. The axial length of the stepped or elbowed end portion of the tubular heating chamber may be from 0.5 percent to 10 percent of the total length of the tubular heating chamber, preferably from 1 percent to 5 percent of the total length of the tubular heating chamber and more preferably approximately 3.7 percent of the total length of the tubular heating chamber. Preferably, a certain radius is provided between the stepped or elbowed portions to eliminate sharp edges and stress concentrators.

The axial length of the flared or funnel-shaped end portion of the tubular heating chamber may be from 0.2 millimeters to 2 millimeters, preferably from 0.4 millimeters to 1 millimeter, and more preferably approximately 0.5 mm.

The tubular heating chamber may have a tubular wall thickness of from 0.05 millimeters to 1.00 millimeters, preferably from 0.05 millimeters to 0.50 millimeters, and more preferably about 0.10 millimeters.

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

The heater unit may comprise at least one electric heating element for heating the aerosol-forming substrate. The heater unit may comprise several electric heating elements. The electric heating element or elements may be arranged around the outer surface of the heating chamber or surround it. The electric heating element or elements may be arranged around the inner surface of the heating chamber or surround it. The electric heating element or elements may be part of the heating chamber or made integral with it.

The electric heating element or elements may comprise an electrically resistive material. Suitable electrically resistive materials include, but are not limited to: semiconductors such as doped ceramics, electrically "conductive" ceramics (such as, for example, molybdenum disilicide), carbon, graphite, metals, metal alloys, and composite materials made from a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable metal alloys include stainless steel, alloys containing nickel, cobalt, chromium, aluminum, titanium, zirconium, hafnium, niobium, molybdenum, tantalum, tungsten, tin, gallium, manganese, gold and iron, and nickel-based, iron-based, cobalt-based superalloys, stainless steel, Timetal ^™ , Kanthal ^™ and other iron-chromium-aluminum alloys and iron-manganese-aluminum alloys. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated in or coated with the insulating material, or vice versa, depending on the energy transfer kinetics and the desired external physicochemical properties.

One or more heating elements may be made using a metal or metal alloy characterized by a certain relationship between temperature and specific resistance. Heating elements formed in this way may be used both for heating and for monitoring the temperature of the heating element during operation.

The heating element may be applied within or on a rigid carrier material or substrate. The heating element may be applied within or on a flexible carrier material or substrate. The heating element may be formed as a track on a suitable insulating material such as ceramics or glass or polyimide film. The heating element may be sandwiched between two insulating materials.

The heater assembly may comprise a flexible heating element arranged around the outer surface of the heating chamber or surrounding it. 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 comprise at least one end portion that is not covered or surrounded by the heating element. An end portion that is not covered or surrounded by the heating element may be provided at both ends of the heating chamber. The end portion or portions may serve as separating portions to prevent direct contact between the heating element and other components of the heater assembly. Each end portion or portions may have a length of less than 2 millimeters, preferably less than 1 millimeter and preferably approximately 0.5 millimeters. Preferably, the separating portions will have a lower temperature during heating than the portion of the heating chamber covered or surrounded by the heating element. The separating portions may comprise funnel-shaped end portions or stepped end portions.

The heating chamber may be configured to accommodate at least a portion of an aerosol generating article (as defined below).

According to one example of the present invention, an aerosol generating device is provided. The aerosol generating device may comprise a heater assembly according to any of the heater assemblies described above. The aerosol generating device may comprise a power supply or a power source for supplying power to the heater assembly.

According to one example of the present invention, an aerosol generating device is proposed. The aerosol generating device comprises a heater unit according to any of the heater units described above, and a power supply or power source for supplying electric power to the heater unit.

The power supply may be any suitable power supply, such as a DC voltage source. In one embodiment, the power supply is a lithium-ion battery. Alternatively, the power supply 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.

Preferably, the aerosol generating device is a hand-held aerosol generating device that is comfortably held by the user between the fingers of one hand.

The aerosol generating device may further comprise a control circuit configured to control the supply of electric power to the heater unit. The control circuit may comprise a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, or an application-specific integrated circuit (ASIC) or other electronic circuit capable of providing control. The control circuit may comprise additional electronic components. For example, in some embodiments, the control circuit may comprise any of: sensors, switches, display elements. The power may be supplied to the heater unit continuously after activation of the device or may be supplied intermittently, for example from puff to puff. The power may be supplied to the heater unit in the form of electric current pulses, for example, by means of pulse width modulation (PWM).

The aerosol generating device may comprise a device casing. The device casing may comprise a heater unit, a power supply unit, and a control circuit. The casing may comprise an opening for accommodating an aerosol generating article. The opening may be connected to an aerosol outlet of the second casing of the heater unit to enable insertion of the aerosol generating article into the heating chamber. The casing may comprise an air inlet. The air inlet may be connected to an air inlet of the first casing of the heater unit.

The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics or composite materials containing one or more of such materials, or thermoplastic materials suitable for applications in the food or pharmaceutical industries, such as polypropylene, polyetheretherketone (PEEK) and polyethylene. The material is preferably lightweight and non-brittle.

According to an example of the present invention, an aerosol generating system is provided, comprising an aerosol generating device according to any of the examples described above. The aerosol generating system may comprise an aerosol generating article, comprising an aerosol forming substrate.

According to an example of the present invention, there is provided an aerosol generating system comprising: an aerosol generating device according to one of the examples described above; and an aerosol generating article comprising an aerosol forming substrate.

In the context of this document, the term "aerosol-generating article" refers to an article containing an aerosol-forming substrate that, when heated in an aerosol-generating device, releases volatile compounds capable of forming an aerosol. The aerosol-generating article is separate from the aerosol-generating device and is designed to be combined with it to heat the aerosol-generating article.

The aerosol-generating article may have a substantially cylindrical shape. The aerosol-generating article may be substantially elongated. The aerosol-forming substrate may have a substantially cylindrical shape. The aerosol-forming substrate may be substantially elongated.

The aerosol-generating article may have a total 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-generating substrate may have a length of about 10 mm to about 18 mm. In addition, the diameter of the aerosol-generating substrate may be from 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 an acetate cellulose filter plug. The filter plug in one embodiment has a length of about 7 mm, but it may have a length of from about 5 mm to about 12 mm.

In one embodiment, the aerosol-generating article may have a total length of about 45 mm. The aerosol-generating article may have an outer diameter of about 7.3 mm, but may have an outer diameter of about 7.0 mm to about 7.4 mm. In addition, the aerosol-generating substrate may have a length of about 12 mm. Alternatively, the aerosol-generating substrate may have a length of about 16 mm. The aerosol-generating article may comprise an outer paper wrapper. In addition, the aerosol-generating article may comprise a gap between the aerosol-generating substrate and the filter plug. The gap may be about 21 mm or about 26 mm, but may be in the range of about 5 mm to about 28 mm. The gap may be provided by a hollow tube. The hollow tube may be made of cardboard or cellulose acetate.

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 comprising 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-forming substance. Examples of suitable aerosol-forming substances include glycerol and propylene glycol.

If the aerosol-forming substrate is a solid aerosol-forming substrate, the solid aerosol-forming substrate may comprise, for example, one or more of the following: powder, granules, pellets, grains, thin tubes, strips or sheets containing one or more of the following: grass leaves, tobacco leaves, tobacco rib fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco and blown tobacco. The solid aerosol-forming substrate may be in bulk 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 intended to be released upon heating of the substrate. The solid aerosol-forming substrate may also contain capsules that, for example, contain additional tobacco or non-tobacco volatile flavor compounds, and such capsules may melt during heating of the solid aerosol-forming substrate.

As used herein, "homogenized tobacco" refers to a material formed by agglomerating loose tobacco. The homogenized tobacco may be in the form of a sheet. The homogenized tobacco material may contain more than 5% by weight of aerosol forming agent on a dry weight basis. Alternatively, the homogenized tobacco material may contain from 5% to 30% by weight of aerosol forming agent on a dry weight basis. Sheets of homogenized tobacco material may be formed by agglomerating loose tobacco obtained by grinding or otherwise comminuting one or both of the lamina of tobacco leaf and the stems of tobacco leaf. Alternatively or additionally, the sheets of homogenized tobacco material may contain one or more of tobacco dust, tobacco fines, and other by-products of the loose tobacco generated, for example, during the processing, handling, and shipping of the tobacco. The sheets of homogenized tobacco material may comprise one or more intrinsic binders, i.e. tobacco endogenous binders, one or more extrinsic binders, i.e. tobacco exogenous binders, or a combination thereof, to promote agglomeration of the bulk tobacco; alternatively or additionally, the sheets of homogenized tobacco material may comprise other additives, including, but not limited to, tobacco and non-tobacco fibers, aerosol forming agents, humectants, plasticizers, flavoring agents, fillers, aqueous and non-aqueous solvents, and combinations thereof.

In a particularly preferred embodiment, the aerosol-forming substrate comprises an assembled corrugated sheet of homogenized tobacco material. As used herein, the term "corrugated sheet" means a sheet having a plurality of substantially parallel ridges or corrugations. Preferably, when the aerosol-generating article is assembled, the substantially parallel folds or corrugations extend along or parallel to the longitudinal axis of the aerosol-generating article. This advantageously simplifies the assembly of the corrugated sheet of homogenized tobacco material to form the aerosol-forming substrate. However, it will be understood that corrugated sheets of homogenized tobacco material for inclusion in an aerosol-generating article may alternatively or additionally have a plurality of substantially parallel folds or corrugations that are located at an acute or obtuse angle 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 assembled sheet of homogenized tobacco material that is substantially uniformly textured over substantially the entire surface. For example, the aerosol-forming substrate may comprise an assembled corrugated sheet of homogenized tobacco material that comprises a plurality of substantially parallel folds or corrugations that are substantially uniformly spaced across the width of the sheet.

Optionally, the solid substrate forming the aerosol can be provided on or embedded in a thermally stable carrier. The carrier can be in the form of a powder, granules, beads, grains, thin tubes, strips or sheets. Alternatively, the carrier can be a tubular carrier having a thin layer of the solid substrate deposited on its inner surface, or on its outer surface, or on both its inner and outer surfaces. Such a tubular carrier can be made, for example, of paper or a paper-like material, a non-woven mat of carbon fibers, a lightweight metal mesh with open cells or a perforated metal foil, or any other thermally stable polymer matrix.

The solid aerosol-forming substrate may be applied to the surface of the carrier in the form of, for example, a sheet, foam, gel or suspension. The solid aerosol-forming substrate may be applied to the entire surface of the carrier or, alternatively, may be applied in a pattern to provide non-uniform delivery of the flavor additive during use.

Although solid aerosol-forming substrates are mentioned above, it will be understood by those skilled in the art that other forms of aerosol-forming substrate may be used with other embodiments. For example, the aerosol-forming substrate may be a liquid aerosol-forming substrate. If a liquid aerosol-forming substrate is provided, the aerosol-generating device preferably comprises means for retaining the liquid. For example, the liquid aerosol-forming substrate may be retained in a container or a portion for storing the liquid. Alternatively or additionally, the liquid aerosol-forming substrate may be absorbed by a porous carrier material. The porous carrier material may be made of any suitable absorbent plug or piece, such as a foamed metal or plastic material, polypropylene, terylene, nylon fibers or ceramics. The liquid aerosol-forming substrate may be retained in the porous carrier material prior to 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 prior to 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 a liquid.

Alternatively, the carrier may be a non-woven web or a bundle of fibers in which tobacco components have been incorporated. The non-woven web or bundle of fibers may contain, for example, carbon fibers, natural cellulose fibers, or fibers from cellulose derivatives.

According to an example of the present invention, a method for manufacturing a heater unit for an aerosol generating device is proposed. The method may include providing a first heater housing containing an air inlet. The method may include providing a second heater housing containing an aerosol outlet. The method may include providing a heating chamber for heating an aerosol-forming substrate. The method may include arranging the heating chamber so that it is in fluid communication with both the air inlet and the air outlet to define an air flow path through the heater unit. The method may include providing a heater mount and installing the heating chamber on the heater mount. The method may include providing a seal for sealing the air flow path. The method may include installing the seal on the heater mount. The method may include arranging the seal at a distance from the heating chamber. The method may include attaching the first and second heater housings to each other to enclose the heating chamber and the heater mount.

According to an example of the present invention, a method for manufacturing a heater assembly for an aerosol generating device is provided, wherein the method comprises: providing a first heater housing comprising an inlet for an aerosol; providing a second heater housing comprising an outlet for air; providing a heating chamber for heating an aerosol-forming substrate, and arranging the heating chamber so that it is in fluid communication with both the inlet for air and the outlet for air to define an air flow path through the heater assembly; providing a heater mount and installing the heating chamber on a heater mount; providing a seal for sealing the air flow path and installing the seal on the heater mount so that it is located at a distance from the heating chamber; and attaching the first and second heater housings to each other to enclose the heating chamber and the heater mount.

The heating chamber can be mounted on the heater mount by pressing. The heating chamber can be pressed into a recess on the other side of the heater mount.

The heating chamber may be attached to the second heater casing by pressing. The heating chamber may be pressed into a recess located on the inner surface of the second heater casing.

The first and second heater housings may be attached to each other using a fastener. A compressive force may be applied to the heater assembly before the first and second heater housings are attached to each other. The first and second heater housings may be attached to each other using the fastener while the compressive force is applied. The compressive force may cease to be applied when the fastener has been attached.

The features described in relation to one of the above examples may equally be applied to other examples according to the present invention.

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

Example Ex1: A heater assembly for an aerosol generating device, wherein the heater assembly comprises: a first heater housing comprising an air inlet; a second heater housing comprising an aerosol outlet; and a heating chamber for heating an aerosol-forming substrate, wherein the heating chamber is in fluid communication with both the air inlet and the aerosol outlet to define an air flow path through the heater assembly.

Example Ex2: A heater assembly according to example Ex1, wherein the heater assembly further comprises: a heater mount, wherein the heating chamber is mounted on the heater mount; and a seal for sealing the air flow path; wherein the seal is mounted on the heater mount so that it is located at a distance from the heating chamber.

Example Ex3: A heater assembly according to example Ex2, wherein the first and second heater casings are attached to each other and enclose the heating chamber and the heater mount, and wherein the seal is located between the heater mount and the inner surface of one of the first and second heater casings.

Example Ex4: A heater assembly according to example Ex2 or Ex3, wherein the seal is located between the heater mount and the inner surface of the first heater casing.

Example Ex5: A heater assembly according to any of examples Ex2-Ex4, wherein the seal is mounted on a first side of the heater mount and the heating chamber is mounted on a second side of the heater mount, wherein the second side is axially opposite to the first side.

Example Ex6: A heater assembly according to any of the examples Ex2-Ex5, wherein the heater mount is located upstream of the heating chamber.

Example Ex7: A heater assembly according to any of examples Ex2-Ex6, wherein the heater fastening comprises a polymer.

Example Ex8: A heater assembly according to any of examples Ex2-Ex7, wherein the seal is located at a distance of at least 2 millimetres from the heating chamber.

Example Ex9: A heater assembly according to example Ex8, wherein the seal is located at a distance of at least 4 millimetres from the heating chamber.

Example Ex10: A heater assembly according to example Ex8 or Ex9, wherein the seal is located at a distance of 4 millimetres to 6 millimetres from the heating chamber.

Example Ex11: A heater assembly according to any of examples Ex2-Ex10, wherein the seal comprises an elastic material.

Example Ex12: A heater assembly according to any of examples Ex2-Ex11, wherein the seal comprises a polymer having a Shore hardness of from 30A to 90A.

Example Ex13: A heater assembly according to any of the examples Ex2-Ex12, wherein the seal is compressed inside the heater assembly.

Example Ex14: A heater assembly according to any of the examples Ex2-Ex13, wherein the seal has a thickness in the uncompressed state from 0.5 mm to 2 mm.

Example Ex15: A heater assembly according to any of examples Ex2-Ex14, wherein the first heater casing, the second heater casing, the heating chamber and the heater mount comprise an air flow channel, wherein the air flow channels are formed in communication with each other to define an air flow path through the heater assembly.

Example Ex16: A heater assembly according to any preceding example, wherein the heating chamber comprises a tubular heating chamber.

Example Ex17: A heater assembly according to example Ex16, wherein the diameter of the tubular heating chamber at each end of the tubular heating chamber is larger than the diameter of the tubular heating chamber in the region between the two ends of the tubular heating chamber.

Example Ex18: A heater assembly according to example Ex16 or Ex17, wherein each end of the tubular heating chamber is flared or funnel-shaped.

Example Ex19: A heater assembly according to example Ex18, wherein the axial length of the flared or funnel-shaped end of the tubular heating chamber is from 0.5 percent to 10 percent of the total length of the tubular heating chamber.

Example Ex20: A heater assembly according to example Ex16 or Ex17, wherein each end of the tubular heating chamber has a stepped or elbow profile.

Example Ex21: A heater assembly according to example Ex20, wherein the axial length of the stepped or elbow end of the tubular heating chamber is from 0.5 percent to 10 percent of the total length of the tubular heating chamber.

Example Ex22: An aerosol generating device comprising: a heater unit according to any of the previous examples; and a power supply unit for supplying electrical power to the heater unit.

Example Ex23: A method of manufacturing a heater assembly for an aerosol generating device, the method comprising: providing a first heater housing comprising an air inlet; providing a second heater housing comprising an aerosol outlet; providing a heating chamber for heating an aerosol-forming substrate and arranging the heating chamber so as to be in fluid communication with both the air inlet and the air outlet to define an air flow path through the heater assembly; providing a heater mount and mounting the heating chamber to the heater mount; providing a seal for sealing the air flow path and mounting the seal to the heater mount so as to be spaced apart from the heating chamber; and

attaching the first and second heater casings to each other to enclose the heating chamber and the heater mount.

Example Ex24: The method according to example Ex23, wherein the heating chamber is mounted on the heater mount by pressing.

Example Ex25: The method according to example Ex23 or Ex24, wherein the heating chamber is attached to the second heater casing by pressing.

The examples will now be further described with reference to the drawing figures, where:

Fig. 1 shows a longitudinal section of a heater assembly according to an example of the present invention.

Fig. 2 is an exploded isometric view of the heater assembly of Fig. 1 prior to assembly, showing the components of the heater assembly spaced axially apart.

Fig. 3A-3C are schematic cross-sectional views of portions of the heater assembly located in the dotted region indicated by A in Fig. 1, illustrating some of the ways in which the sealing of the heater assembly helps to absorb longitudinal tolerances.

Fig. 3D is a schematic illustration of the portions of the heater assembly located in the dotted area indicated by A in Fig. 1, showing how the heater assembly seal helps to absorb tilt tolerances.

Fig. 4A and 4B are side views of two exemplary heating chambers for use in a heater assembly according to the present invention.

Figs. 5A-5C are schematic partial cross-sectional views of known tubular heating chambers showing problems that may arise due to process tolerances resulting from pressing the heating chambers into the heater housing.

Fig. 5D is a schematic cross-sectional view of the upper portion of the heating chamber of Fig. 4A, showing its press fit in a recess in the heater casing.

Fig. 6 is a schematic sectional view showing the inside of an aerosol generating device according to an example of the present invention and an aerosol generating article disposed inside the aerosol generating device.

Fig. 1 shows a longitudinal section of a heater unit 1 comprising a first heater housing 2, a second heater housing 4, a heating chamber 6 for heating an aerosol-forming substrate, and a heater mount 8. The first heater housing 2 comprises a first hollow section 2a of the casing and a first tubular section 2b. The first hollow section 2a of the casing comprises an internal cavity 2c which surrounds the heater mount 8. An air inlet (not shown) is located at the distal end of the first tubular section 2b, wherein the first tubular section 2b extends distally from the first hollow section 2a of the casing in a direction parallel to the longitudinal axis X-X of the heater unit 1.

The second heater housing 4 comprises a second hollow section 4a of the shell and a second tubular section 4b. The second hollow section 4a of the shell comprises an internal cavity 4c which surrounds the heating chamber 6. The outlet opening 10 for the aerosol is located at the near end of the second tubular section 4b, wherein the second tubular section 4b extends proximally from the second hollow section 4a of the shell in a direction parallel to the longitudinal axis X-X of the heater unit 1. The outlet opening 10 for the aerosol is defined by an opening 12 which is configured to receive an aerosol-generating article (not shown). The aerosol exits from the opening 10 through the aerosol-generating article placed in the heating chamber 6. The first 2 and second 4 heater housings are attached to each other and cover the heating chamber 6 and the heater mount 8.

The heating chamber 6 comprises a tubular heating chamber formed from a stainless steel pipe. The ends 6a, 6b of the tubular heating chamber 6 are flared or funnel-shaped, the reasons for which are discussed in more detail below. A heating element (not shown) is arranged around the outer surface of the heating chamber for heating the heating chamber 6, which in turn heats an aerosol-forming substrate (not shown) located inside the inner space of the tubular heating chamber 6. The heating element comprises a heat-resistant flexible polyimide film comprising resistive heating tracks that typically form a loop-shaped pattern on the film. The resistive heating tracks are connected to an electric power source (not shown) and generate heat when an electric current is passed through them. Although not shown in Fig. 1, the heating element is arranged around substantially the entire length of the tubular heating chamber 6, except for the funnel-shaped ends, for heating substantially the entire length of the tubular heating chamber 6.

The first 2 and second 4 heater casings are made of polyetheretherketone (PEEK) due to its preferable mechanical and thermal insulation properties. The walls of the internal cavities 2c and 4c of the first and second heater casings are respectively located at a distance in the radial direction from the heating chamber 6 and the heater mount 8 with the definition of a hollow air gap 13 around the heating chamber 6 and the heater mount 8. The hollow air gap 13 helps to provide thermal insulation for the heating chamber 6, which helps to reduce heat losses from the heating chamber 6 and also helps to reduce heat transfer to the outside of the heater assembly 1 and the aerosol generating device.

The heater mount 8 is located inside the first heater casing 2. The first side 8a of the heater mount 8 is located adjacent to the base or the distant end wall of the first hollow section 2a of the casing. The heating chamber 6 is mounted on the second side 8b of the heater mount 8, wherein the second side 8b is located axially opposite to the first side 8a in the direction parallel to the longitudinal axis X-X of the heater unit 1. The first end 6a of the heating chamber 6 is pressed inside the first recess 14 made in the second side 8b of the heater mount 8. The second end 6b of the heating chamber 6 is pressed inside the second recess 16 made in the second heater casing 4 in the upper or near end wall of the second hollow section 4a of the casing and at the distant end of the second tubular section 4b. The heater mount 8 is made of PEEK due to its preferable mechanical and thermal insulation properties.

The heater mount 8 comprises an internal air flow channel 18 which extends axially along the length of the heater mount 8 in a direction parallel to the longitudinal axis X-X of the heater unit 1. The air flow channel 18 of the heater mount 8 is in fluid communication with the air flow channel 20 defined by the internal space of the tubular heating chamber 6, wherein the air flow channel 20 extends axially along the length of the heating chamber 6 in a direction parallel to the longitudinal axis X-X of the heater unit 1. In addition, the first tubular section 2b of the first heater casing 2 comprises an air flow channel 22, and the second tubular section 4b of the second heater casing 4 comprises an air flow channel 24. The air flow 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 are respectively in fluid communication with each other to define an air flow 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.

The heater mount 8 comprises a ledge or stop 28 formed in the inner surface of the heater mount 8 inside its air flow channel 18. The stop 28 is arranged to engage with the distal end of the aerosol-generating article (not shown) to prevent the distal end of the aerosol-generating article from moving beyond the stop 28 and to accurately position the aerosol-forming substrate provided inside the aerosol-generating article inside the heating chamber 6.

An elastomeric polymer seal 30 in the form of a sealing ring made of rubber based on a copolymer of ethylene, propylene and diene monomer (EPDM) is mounted on the heater mount 8. The seal 30 is mounted on the first side 8a of the heater mount 8 between the heater mount 8 and the far end wall of the first hollow section 2a of the shell of the first heater casing 2. The seal in the form of a sealing ring surrounds the air flow path 26 through the heater assembly 1. A recess 32 is formed in the first side 8a of the heater mount 8 for receiving a seal 30. The seal 30 has a Shore hardness of 70A, as determined according to the technical standard ISO868 using type A. This hardness was found to be soft enough to absorb the permissible deviations in the longitudinal direction and at tilts, as discussed in more detail below, but also hard enough to apply a force to the heater assembly 1 to ensure the sealing of the air flow path 26 and the integrity of the heater assembly 1. The seal 30 has a thickness or diameter in the uncompressed state of 1 millimeter. This thickness was also found to be suitable for absorbing the permissible deviations in the longitudinal direction and at tilts and for applying a force to the heater assembly 1 to ensure the sealing of the air flow path 26 and the integrity of the heater assembly 1.

By installing the seal 30 on the first side 8a of the heater mount 8 and installing the heating chamber 6 on the second side 8b of the heater mount 8, the seal 30 is removed or made at a distance from the heating chamber 6. With such an arrangement, at least a portion of the heater mount 8 is located between the seal 30 and the heating chamber 6. This reduces heat transfer with respect to the seal 30 and helps to maintain a lower temperature of the seal 30 than that of the heating chamber 6. As indicated above, the heater mount is made of PEEK, which has a lower thermal conductivity than the heating chamber, which is made of stainless steel. This helps to further reduce heat transfer with respect to the seal 30 and to maintain a lower temperature of the seal 30 than that of the heating chamber. Therefore, in the arrangement of Fig. 1, the seal 30 has a lower temperature than when it is in direct contact with the heating chamber, which helps to maintain the integrity of the seal 30 to provide improved sealing.

The seal 30 is elastic and compresses to some extent when the heater assembly 1 is assembled. The elasticity of the seal 30 applies an axial force to the heater mount 8 in a direction parallel to the longitudinal axis X-X of the heater assembly 1. Since the heater mount 8 is aligned in the axial direction with the heating chamber 6, which, in turn, is aligned in the axial direction with the second tubular section 4b, the seal 30 helps to ensure that these components enter into a sealing interaction with each other to seal the air flow path 26 and reduce the likelihood of an aerosol leaking out of the air flow path 26 at the intersection point between the two components. The seal 30 also provides a gas-tight seal between the heater mount 8 and the first heater casing 2.

Fig. 2 is an exploded isometric view of the heater assembly 1 of Fig. 1 before assembly. The components of the heater assembly 1, i.e. the first heater housing 2, the heater mount 8, the seal 30, the heating chamber 6 and the second heater housing 4, are shown separated in the axial direction in Fig. 2. To assemble the heater assembly 1, the seal 30 is first mounted on the first side 8a of the heater mount 8. The subassembly of the heater mount 8 and the seal 30 is then mounted inside the first hollow section 2a of the shell of the first heater housing 2. The hollow plug 8c, which extends distally relative to the first side 8a of the heater mount 8, is pressed into an internal recess (not shown) formed in the near end of the first tubular section 2b.

The heating chamber 6 is then pressed into an internal recess (not shown in Fig. 2, but the second recess 16 is visible in Fig. 1) formed in the near end wall of the second hollow section 4a of the shell 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 inside the heating chamber 6 to maintain axial alignment of the components. The subassembly of the second heater casing 4 and the heating chamber 6 is then mounted on the subassembly comprising the first heater casing 2, the seal 30 and the heater mount 8. The far end of the guide is inserted into an internal air flow channel (not shown) of the heater mount 8 to maintain alignment of the components. The first 2 and second 4 heater casings are then secured to each other by means of two bolts 34 and washers 36. The guide is then removed. When the first 2 and second 4 heater housings are fastened, the seal 30 is compressed, which then applies an axial force, as discussed above, with maintaining the sealing interaction of the components of the heater unit 1 in the axial direction and with sealing the air flow path through the heater unit. The air flow path is therefore sealed between the air inlet 38, located at the far end of the first tubular section 2b of the first heater housing 2, and the aerosol outlet 10, located at the near end of the second heater housing 4.

Fig. 3A-3C are schematic sectional views of portions of the heater assembly 1 located in the dotted region indicated by A in Fig. 1, illustrating some of the ways in which the seal of the heater assembly helps to absorb longitudinal tolerances. Referring to Fig. 3A, the lower portion of the tubular heating chamber 6 is shown engaged with the upper, or second side 8b, of the heater mount 8. The seal 30 is located on the lower, or first side, of the heater mount 8 and between the heater mount 8 and the first heater casing 2. The seal 30 has a circular cross-section in a longitudinal plane in its uncompressed state, but is axially compressed to some extent in a direction parallel to the longitudinal axis X-X (see Fig. 1) of the heater assembly when the heater assembly is assembled. Therefore, in Fig. 3A it is shown as having a flattened or oval cross-section to illustrate the effect of the axial compression.

In the example of Fig. 3A, the tubular heating chamber 6, the heater mount 8 and the second heater jacket 2 have the correct specified design length. The horizontal dotted line B-B marks the surface level at which the heating chamber 6 and the heater mount 8 intersect in Fig. 3A. The horizontal line B-B also runs through Figs. 3B and 3C and serves as a reference level to show where the heating chamber 6 and the heater mount 8 should intersect if the heating chamber 6 has the correct length.

In Fig. 3B, the heating chamber 6 is too short, that is, the length of the heating chamber 6 is shorter than its specified design length by a distance d ₁ . However, its length is still within the permissible manufacturing tolerances. In this case, the seal 30 is less compressed in the axial direction compared to its compressed state in Fig. 3A by an amount corresponding to the distance d ₁ , in order to absorb the reduction in length caused by the permissible manufacturing tolerance in the longitudinal direction. In its compressed state in Fig. 3B, the seal is still characterized by sufficient compression to ensure that the components of the heater assembly enter into axial engagement to seal the air flow path through the heater assembly and still provides an airtight seal between the heater mount 8 and the first heater casing 2.

In Fig. 3C, the heating chamber 6 is too long, that is, the length of the heating chamber 6 is greater than its specified design length by a distance d ₂ . However, its length is still within the limits of the permissible manufacturing tolerances. In this case, the seal 30 is more compressed in the axial direction compared to its compressed state in Fig. 3A by an amount corresponding to the distance d ₂ , in order to absorb the excess length caused by the permissible manufacturing tolerance in the longitudinal direction. In its more compressed state, the seal is still capable of ensuring the entry of the components of the heater assembly into axial engagement for sealing the air flow path through the heater assembly and still provides an airtight seal between the heater mount 8 and the first heater casing 2.

It should be borne in mind that the elasticity and thickness of the seal 30 can be used to compensate for permissible deviations in the longitudinal direction of other components, such as the heater mount 8 or the second heater casing 2, in addition to the heating chamber 6, just as shown in Fig. 3B and 3C.

Fig. 3D is a schematic sectional view of parts of the heater assembly 1 located in the dotted area indicated by A in Fig. 1, similar to Figs. 3A-3C. This figure shows how the seal 30 of the heater assembly helps to absorb the tolerances during tilts. In Fig. 3D, the right side 2r of the first heater housing 2 relative to the left side 2l of the first heater housing 2 is at a level in the axial direction that differs by a distance d ₃ in the direction parallel to the longitudinal axis XX (see Fig. 1) of the heater assembly. This is caused by the tolerance of the manufacturing tolerance during tilt and would lead to a tilt of the heater mount 8 and the heating chamber 6 if the heater mount 8 were directly mounted on the first heater housing 2. The dotted line CC shows the correct specified design height or level of the first heater housing. In this case, the left side 30l of the seal 30 is characterized by a standard amount of compression, as shown in Fig. 3A. The right side 30r of the seal 30 is more compressed in the axial direction compared to the left side 30r of the seal 30 by an amount corresponding to the distance d ₃ , to absorb the difference in level caused by the permissible technological deviation when tilting. In this state, the seal is still able to ensure the entry of the components of the heater assembly into axial engagement to seal the air flow path through the heater assembly and still provides an airtight seal between the heater mount 8 and the first heater casing 2.

It should be noted that Figs. 3A-3D are schematic and not drawn to scale. For clarity, the figures have been simplified by omitting some details and changing or increasing the size of features.

Fig. 4A and 4B are side views of two exemplary heating chambers for use in a heater assembly according to the present invention. Referring to Fig. 4A, a first exemplary heating chamber 6A is shown. The heating chamber 6A comprises a stainless steel pipe having a circular cross-section. A hollow internal space within the tubular heating chamber 6A has an internal diameter substantially corresponding to the external diameter of an aerosol-generating article, so that the tubular heating chamber 6A can receive an aerosol-generating article (not shown) within the internal space. A portion 7a of the heating chamber 6A at each end of the heating chamber 6A is flared outward to form a funnel shape at each end of the heating chamber 6A. Each of the flared portions 7a has a length l ₁ , and the percentage of the total length l of the heating chamber 6A, which each length l ₁ of the flared portions constitutes, can be in the range from 1 to 5 percent. Each of the flared end portions 7a of the heating chamber 6A forms an angle of approximately 45 degrees with the longitudinal axis of the heating chamber 6A. Due to the flared end portions 7a, the outer diameter D at the two ends of the heating chamber 6A is larger than the outer diameter d of the heating chamber 6A between the two flared end portions 7a.

The portion 9a of the heating chamber 6A between the two flared end portions 7a has straight sides which are parallel to the longitudinal axis of the heating chamber 6A. The straight portion 9a of the heating chamber 6A has a length l ₂ which substantially corresponds to the length of the aerosol-forming substrate provided in the aerosol-generating article configured to be placed inside the heating chamber 6A. Substantially the entire length l ₂ of the straight portion 9a of the heating chamber 6A is surrounded by a flexible heating element (not shown, but described above with reference to Fig. 1). The flared portions 7a of the heating chamber 6A are not surrounded by the heating element and serve as separators between the ends of the heating element and the components which hold the heating chamber 6A, i.e. the heater mount and the second heater casing, and help to prevent direct contact between these components and the heating element.

With reference to Fig. 4B, a second exemplary heating chamber 6B is shown. The heating chamber 6B has essentially the same structure as the heating chamber 6A in Fig. 4A, with the exception that instead of flared end portions, the heating chamber 6B has stepped or cranked end portions 7b. That is, a portion 7b of the heating chamber 6B at each end of the heating chamber 6B is stepped or cranked in a radially outward direction to form a step at each end of the heating chamber 6B. Each of the stepped portions 7b has a length l ₁ , and the percentage of the total length l of the heating chamber 6B that each length l ₁ of the stepped portions constitutes may be in the range of from 1 to 5 percent. Due to the stepped end portions 7b, the outer diameter D at the two ends of the heating chamber 6B is larger than the outer diameter d of the heating chamber 6B between the two stepped end portions 7b.

The portion 9b of the heating chamber 6B between the two stepped end portions 7b has straight sides that are parallel to the longitudinal axis of the heating chamber 6B. The straight portion 9b of the heating chamber 6B has a length l ₂ that substantially corresponds to the length of the aerosol-forming substrate provided in the aerosol-generating article configured to be placed inside the heating chamber 6B. Substantially the entire length l ₂ of the straight portion 9b of the heating chamber 6B is surrounded by a flexible heating element (not shown, but described above with reference to Fig. 1). The stepped portions 7b of the heating chamber 6B are not surrounded by a heating element and serve as separators 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, and help to prevent direct contact between these components and the heating element. The heating chamber 6B also comprises a transition portion 11 between each stepped portion 7b and the straight portion 9b to provide an inclined or curved transition between the outer diameter D of each stepped portion and the outer diameter d of the straight portion.

Fig. 5A-5C are schematic cross-sectional views of portions of prior art straight wall tubular heating chambers illustrating problems that can arise from manufacturing tolerances in the process of pressing such heating chambers into engagement with the heater shell. Manufacturing tolerances can result in components being larger or smaller than the specified design length, which can lead to problems with joining tightly fitted components. Achieving very accurate manufacturing tolerances is more problematic in rapid manufacturing technologies such as injection molding.

With reference to Fig. 5A, there is shown the upper part of a known or conventional tubular heating chamber 6 pressed into a recess 16 in the upper casing 4 of the heater. The entire length of the tubular heating chamber 6 is straight, that is, it has a constant outer diameter along its entire length, and the tubular heating chamber 6 does not have a flared or stepped end portion, like the tubular heating chambers 6A and 6B in Figs. 4A and 4B. As can be seen in Fig. 5A, the inner diameter d ₁ of the heating chamber 6 is smaller than the inner diameter d ₂ of the opening 15 in the heater casing 4, through which the aerosol-generating article passes during the insertion of the aerosol-generating article into the heating chamber 6. As a result, a portion with a thickness t of each of the walls, i.e. the end surface, of the heating chamber 6 projects into the inner space defined by the inner diameter d2 of the opening 15. This forms a sharp projection 17 in the opening 15, which may damage the aerosol-generating article when the aerosol-generating article is inserted through the opening 15, or may make the insertion of the aerosol-generating article impossible. A similar situation may arise if the width w of the recess 16 is less than the thickness t of the walls of the tubular heating chamber 6. In this case, there is not enough space inside the recess 16 to accommodate the ends of the tubular heating chamber 6, and, therefore, the ends will protrude into the internal space defined by the internal diameter d2 of the opening 15.

It should be noted that a situation similar to that shown in Fig. 5A may occur at the lower, or upstream, end of the tubular heating chamber 6. Sharp projections at the upstream end of the heating chamber may present a problem in that residues or deposits form in the cracks formed by the projection, which may be difficult to remove or clean out with a cleaning tool.

In Fig. 5B, a lower part of a known or conventional tubular heating chamber 6 is shown, pressed into a recess 14 in a lower casing 2 of the heater. As in Fig. 5A, the entire length of the tubular heating chamber 6 is straight. The inner diameter d3 of the heating chamber 6 is larger than the inner diameter d4 of the opening 19 formed in the lower casing 2 of the heater, through which a part of the aerosol-generating article protrudes, when the aerosol-generating article is properly positioned in the heating chamber 6. As a result, a sharp projection 21 is formed in the opening 19, which can damage the aerosol-generating article when the aerosol-generating article passes through the opening 19, or can make it impossible to completely insert the aerosol-generating article.

It should be noted that a situation similar to that shown in Fig. 5B may occur at the upper, or downstream, end of the tubular heating chamber 6. Sharp projections at the downstream end of the heating chamber may present a problem in that residues or deposits form in the cracks formed by the projection, which may be difficult to remove or clean out with a cleaning tool.

Fig. 5C shows the upper part of a known or conventional tubular heating chamber 6 to be pressed into a recess 16 in the upper heater casing 4. As in Fig. 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 the insertion of the aerosol-generating article into the heating chamber 6. As a result, pressing is impossible in this case, since the tubular heating chamber 6 would simply pass through the opening 15.

Fig. 5D is a schematic cross-sectional view of the upper portion of the tubular heating chamber 6A according to Fig. 4A. As described above, the tubular heating chamber 6A has walls with a funnel-shaped or flared end portion 7a. The flared end portion 7a has been pressed into the recess 16 of the second heater casing 4. The outer diameter D of the flared end portion 7a is larger than the outer diameter d of the portion of the tubular heating chamber 6A between the two flared end portions 7a (only one flared end portion is visible in Fig. 5D). The outer diameter D of the flared end portion 7a is also larger than the inner diameter d ₇ of the opening 15 in the heater casing 4, through which the aerosol-generating article passes during the insertion of the aerosol-generating article into the heating chamber 6. The outer diameter D of the flared end portion 7a is larger than the inner diameter d ₇ of the opening 15, even when permissible technological deviations of the inner diameter d ₇ in the radial or transverse directions are taken into account.

The arrangement according to Fig. 5D significantly reduces the probability of protruding a portion of the end surfaces 6c of the walls of the tubular heating chamber 6A within the diameter d ₇ and the cross-section of the air flow path, which is defined in Fig. 5D by the diameter d ₇ . In addition, the end surfaces 6c of the walls of the tubular heating chamber 6A are located at an angle relative to the cross-section of the air flow path defined by the diameter d ₇ , which further reduces the probability of protruding a portion of the end surfaces 6c of the walls of the tubular heating chamber 6A into the air flow path. The arrangement according to Fig. 5D and, in particular, the use of the tubular heating chamber 6A with flared or funnel-shaped end portions 7a make it possible to use components with large permissible deviations in the radial or transverse directions and are therefore suitable for rapid manufacturing technologies. The arrangement according to Fig. 5D also significantly reduces the risk of damage to the aerosol generating article when the aerosol generating article is inserted into the heating chamber 6A.

It should be noted that the tubular heating chamber 6B of Fig. 4B could also be used in the arrangement of Fig. 5D instead of the heating chamber 6A with the same advantages. The larger outer diameter D in the region of the stepped end portions 7b of the heating chamber 6B reduces the likelihood of a portion of the end surfaces of the walls of the tubular heating chamber 6B protruding within the diameter d ₇ of Fig. 5D and into the air flow path. The heating chamber 6B also makes it possible to use components with large tolerances in the radial or transverse directions and reduces the risk of damage to the aerosol-generating article when the aerosol-generating article is inserted into the heating chamber 6B.

It should be noted that Figs. 5A-5D are schematic and not drawn to scale. For clarity, the figures have been simplified by omitting some details and changing or increasing the size of features.

Fig. 6 is a schematic cross-sectional view showing the interior of the aerosol generating device 100 and the aerosol generating article 200 disposed inside the aerosol generating device 100. Together, the aerosol generating device 100 and the aerosol generating article 200 form an aerosol generating system. In Fig. 6, the aerosol generating device 100 is shown in a simplified manner. In particular, the elements of the aerosol generating device 100 are not shown to scale. In addition, elements that are not essential for understanding the aerosol generating device 100 have been omitted.

The aerosol generating device 100 comprises a housing 102 comprising a heater assembly 1 of Fig. 1, a power supply unit 103 and a control circuit 105. Fig. 6 shows a first heater housing 2, a heating chamber 6, a heater mount 8 and a second heater housing 4. As described above with reference to Fig. 1, the heating chamber 6 comprises a flexible heating element (not shown) arranged around it for heating the heating chamber 6. The power supply unit 103 is a battery, and in this example it is a rechargeable lithium-ion battery. The control circuit 105 is connected to both the power supply unit 103 and the heating element and controls the supply of electrical energy from the power supply unit 103 to the heating element to regulate the temperature of the heating element.

The housing 102 comprises an opening 104 at the near, or mouthpiece, end of the aerosol generating device 100, through which the aerosol generating article 200 is inserted. The opening 104 is connected to the opening 12 in the heater unit 1 of Fig. 1, through which the aerosol exits the heater unit 1. However, it should be borne in mind that the aerosol mainly exits the heater unit 1 and the aerosol generating device 100 through the aerosol generating article 200. The housing 102 further comprises an air inlet 106 at the far end of the aerosol generating device 100. The air inlet 106 is connected to an air inlet located at the far end of the first tubular section 2b of the first heater housing 2. The first tubular section 2b delivers air from the air inlet 106 to the heating chamber 6.

The aerosol-generating article 200 comprises an end plug 202, an aerosol-forming substrate 204, a hollow tube 206 and a mouthpiece filter 208. Each of the above-mentioned components of the aerosol-generating article 100 is a substantially cylindrical element, wherein each of them has a substantially identical diameter. The components are arranged sequentially in an adjacent coaxial alignment and are surrounded by an outer paper wrapper 210 to form a cylindrical rod. The aerosol-forming substrate 204 is a tobacco rod or rod containing an assembled sheet of corrugated homogenized tobacco material surrounded by a wrapper (not shown). The corrugated sheet of homogenized tobacco material contains glycerin as an aerosol-forming substance. The end plug 202 and the filter 208 of the mouthpiece are made of acetyl cellulose fibers.

The distal end of the aerosol generating article 200 is inserted into the aerosol generating device 100 through the opening 104 in the casing 102 and is pushed into the aerosol generating device 100 until it rests against a stop (not shown in Fig. 6) located on the heater mount 8, at which point it is fully inserted. The stop helps to correctly position the aerosol forming substrate 204 inside the heating chamber 6, so that the heating chamber 6 can heat the aerosol forming substrate 204 to form an aerosol.

The aerosol generating device 100 may further comprise: 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 the remaining battery charge, heating status, and error messages.

In use, the user inserts the aerosol-generating article 200 into the aerosol-generating device 100, as shown in Fig. 6. The user then starts a heating cycle by activating the aerosol-generating device 100, such as by pressing a switch to turn on the device. In response to this, the control circuit 105 controls the supply of electric power from the power supply unit 103 to the 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 a range of predetermined temperatures according to a temperature profile. The heating cycle can last approximately 6 minutes. The 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 inside the aerosol generation chamber formed by the hollow tube 206. During the heating cycle, the user places the filter 208 of the mouthpiece of the aerosol generating article 200 between the lips of his mouth and puffs or inhales through the filter 208 of the mouthpiece. The generated aerosol is then drawn through the filter 102 of the mouthpiece into the user's mouth.

For the purpose of the present specification and the appended claims, except where otherwise indicated, all numbers expressing quantities, amounts, percentages, etc., are to be understood as modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therebetween that may or may not be specifically recited herein. Therefore, in this context, the number A is to be understood as A ± 5 percent (5%) of A. In this context, the number A may be considered to include numerical values that are within the normal standard error for the measurement of the property that the number A modifies. The number A, in some instances, when used in the appended claims, may deviate by the percentages listed above, provided that the amount by which A deviates does not materially affect the essential and novel characteristic(s) of the claimed invention. Also, all ranges include the disclosed maximum and minimum points and include any intermediate ranges therebetween that may or may not be specifically listed herein.

Claims (34)

1. A heater assembly for an aerosol generating device comprising: a first heater housing comprising an air inlet; a second heater housing comprising an aerosol outlet; and a heating chamber for heating an aerosol-forming substrate, wherein the heating chamber is in fluid communication with the air inlet and the aerosol outlet to form an air flow path through the heater assembly; in this case, the heater unit additionally contains: a heater mount, wherein the heating chamber is mounted on the heater mount; and seal for sealing the air flow path; wherein the seal is installed on the heater mount with the seal located at a distance from the heating chamber; and wherein the seal is installed on the first end of the heater mount, and the heating chamber is installed on the second end of the heater mount, wherein the second end is axially opposite to the first end. 2. The assembly according to claim 1, in which the first and second heater casings are attached to each other and enclose the heating chamber and the heater mount, and the seal is located between the heater mount and the inner surface of one of the first and second heater casings. 3. An assembly according to any one of paragraphs 1, 2, in which the seal is located between the heater mount and the inner surface of the first heater casing. 4. An assembly according to any of the preceding paragraphs, wherein the heater mount is located upstream of the heating chamber. 5. An assembly according to any of the preceding claims, wherein the heater mount comprises a polymer. 6. An assembly according to any of the preceding claims, wherein the seal is located at a distance of from 4 mm to 6 mm from the heating chamber. 7. An assembly according to any of the preceding claims, wherein the seal comprises a polymer having a Shore hardness of from 30A to 90A. 8. An assembly according to any of the preceding claims, wherein the seal has an uncompressed thickness of from 0.5 mm to 2 mm. 9. An assembly according to any of the preceding claims, wherein each element of the first heater housing, the second heater housing, the heating chamber and the heater mount comprises an air flow channel, wherein the air flow channels are formed in communication with each other to form an air flow path through the heater assembly. 10. An assembly according to any of the preceding claims, wherein the heating chamber comprises a tubular heating chamber. 11. The assembly of claim 10, wherein the diameter of the tubular heating chamber at each end of the tubular heating chamber is greater than the diameter of the tubular heating chamber in the region between the two ends of the tubular heating chamber. 12. An assembly according to any one of paragraphs. 10, 11, in which each end of the tubular heating chamber is flared or has a funnel-shaped form. 13. The assembly according to claim 12, wherein the axial length of the flared or funnel-shaped end of the tubular heating chamber is from 0.5% to 10% of the total length of the tubular heating chamber. 14. An assembly according to any one of paragraphs. 11-13, in which each end of the tubular heating chamber has a stepped or elbow profile. 15. The assembly according to claim 14, wherein the axial length of the stepped or elbow end of the tubular heating chamber is from 0.5% to 10% of the total length of the tubular heating chamber. 16. An assembly according to any of the preceding claims, wherein the heating chamber is configured to accommodate at least a portion of the aerosol generating article. 17. An aerosol generating device comprising: a heater assembly according to any of the preceding paragraphs; and power supply for supplying electrical power to the heater unit. 18. A method for manufacturing a heater unit for an aerosol generating device, comprising: providing a first heater housing containing an air inlet; providing a second heater housing containing an outlet for the aerosol; providing a heating chamber for heating an aerosol-forming substrate, and arranging the heating chamber in fluid communication with the air inlet and the air outlet to form an air flow path through the heater assembly; providing a heater mount and installing a heating chamber on the heater mount; providing a seal for sealing the air flow path and installing the seal on the heater mount with the seal located at a distance from the heating chamber, wherein the seal is mounted on a first end of the heater mount, and the heating chamber is mounted on a second end of the heater mount, wherein the second end is axially opposite the first end; and attaching the first and second heater casings to each other to enclose the heating chamber and the heater mount.