Heating apparatus for an aerosol generating device

Abstract

A heating apparatus (108) for an aerosol generating device (100) is disclosed and comprises: a tube (110) having an inner surface (112) and an outer surface (114) and defining a cavity (109) positioned inwardly of the inner surface in which an aerosol forming substance can be received; and an infra-red heater (116) embedded in the tube in a solid structure, between the inner surface and the outer surface, and configured to emit infra-red radiation to heat an aerosol generating substance received in the cavity; wherein the tube is substantially transparent to infra-red radiation to enable the transmission of infra-red radiation from the infra-red heater to the cavity.

Description

[0001] HEATING APPARATUS FOR AN AEROSOL GENERATING DEVICE

[0002] FIELD OF INVENTION

[0003] The invention relates to a heating apparatus. Specifically, the invention relates to a heating apparatus for an aerosol generating device.

[0004] BACKGROUND TO THE INVENTION

[0005] There is a demand for more efficient aerosol generating devices that are convenient to use. Additionally, there is a demand for aerosol generating devices that are easier to manufacture.

[0006] It is an object of the present invention to address these demands.

[0007] SUMMARY OF INVENTION

[0008] According to a first aspect of the present invention, there is provided a heating apparatus for an aerosol generating device, comprising: a tube having an inner surface and an outer surface and defining a cavity positioned inwardly of the inner surface in which an aerosol forming substance can be received; and an infra-red heater embedded in the tube in a solid structure, between the inner surface and the outer surface, and configured to emit infra-red radiation to heat an aerosol generating substance received in the cavity; wherein the tube is substantially transparent to infra-red radiation to enable the transmission of infrared radiation from the infra-red heater to the cavity.

[0009] In this way, an efficient mechanism for heating an aerosol generating substance in the cavity is provided. The aerosol generating substance in the cavity absorbs the radiation from the infra-red heater and is quickly heated to aerosol generating temperatures. The infra-red heater is embedded within the tube in a solid structure. This makes the heating apparatus easier to manufacture because the infra-red heater can be secured in place within the tube while the tube is being formed, in a single manufacturing step. Additionally, the need for separate holding means for the infra-red heater within the tube is avoided and the infra-red heater can be prevented from becoming dislodged within the tube, which improves the consistency of the aerosol generation over the lifetime of the heating apparatus. Embedding the infra-red heater directly in the tube can also improve the efficiency of the heating apparatus. Additionally, the cavity can be easily cleaned and the tobacco residue can be easily removed from the cavity after extraction of the aerosol forming substance. To further simplify the cleaning, the inner surface of the cavity can be made substantially smooth.

[0010] In other words, embedding the heater in the solid structure means the infra-red heater can be encased inside or within the material of the tube, which prevents dislodging of the heater in the apparatus.

[0011] The infra-red heater may be configured to emit radiation with an intensity profile having a peak wavelength within the infra-red band, which can be defined as about 700 nm to about 1 mm. Preferably, the infra-red heater has a peak wavelength in the range of 2 to 10 pm, which may be able to penetrate from 0.5 to 3 mm into a consumable. The peak wavelength or emitting range of the infrared heater may be selected based on the distance of the infra-red heater to the centre of the cavity to ensure that a sufficient amount of radiation penetrates the central region of the aerosol generating substance. The infra-red heater can be configured to mainly emit infra-red radiation so that heating of the tube or other components of the heating apparatus is minimised. For example, the infra-red heater may emit 75%, 80%, 90%, 95% or more of its total power in the infra-red band.

[0012] The solid structure can be a material of the tube that forms (i.e. , is integral and continuous with) the inner surface and the outer surface. Thus, the tube can comprise a solid annular cylinder. The solid annular cylinder can have a circular, square, or any other suitable cross-sectional shape.

[0013] Preferably, the heating apparatus comprises a reflective layer provided on the outer surface of the tube. In this way, infra-red radiation emitted towards the outer surface is reflected back towards the cavity to provide a more efficient heating apparatus. The reflective layer can comprise any suitable material, such as aluminium or white paint. The reflective layer can be provided as a wrapping or coated directly onto the outer surface of the tube.

[0014] Preferably, the aerosol generating device further comprises an insulator surrounding the reflective layer. In this way, heat can be maintained within the cavity more effectively. The insulator can be any suitable insulating material and may comprise Microlite® or Q-fiber® insulation in some examples.

[0015] Preferably, the infra-red heater is present along 50-80% of the length of the tube along the longitudinal axis of the tube. This may provide an effective balance between efficiency and thorough heating of a consumable.

[0016] Preferably, the infra-red heater is arranged helically about a longitudinal axis of the tube. In this way, the surface area of the infra-red heater facing the cavity can be maximised, which causes the infra-red heater to emit more radiation and heat the aerosol generating substance faster. In other embodiments, the infrared heater can also be arranged longitudinally, i.e., substantially parallel to a longitudinal axis of the tube. The infra-red heater can comprise a wire or strip that is arranged helically or longitudinally.

[0017] Preferably, the infra-red heater has a cross sectional shape that is non-circular. The infra-red heater may have a cross sectional shape that is non-circular when the infra-red heater is arranged helically about the longitudinal axis of the tube. In this way, the surface area of the heater can be maximised further so that more radiation is emitted towards the cavity during use.

[0018] Preferably, the infra-red heater has a substantially octagonal or star-shaped or circular cross-sectional shape. In this way, the surface area of the infra-red heater can be increased further with respect to a circular cross-sectional shape. This arrangement may be particularly preferred when the infra-red heater is arranged helically about the longitudinal axis of the tube.

[0019] Where the infra-red heater is arranged helically, it would be understood that the term “cross-sectional shape” refers to a cross section of the helical arrangement of the infra-red heater. Preferably, the tube comprises glass. A glass tube may be preferable because glass is cheaper and easier to clean compared to other materials and can absorb very low amounts of infra-red radiation. Alternatively, the tube may comprise glass quartz, which may be more durable than other types of glass. In other embodiments, the tube may comprise any other suitable material that is substantially transparent to infra-red radiation.

[0020] Preferably, the infra-red heater comprises ceramic or carbon fibre. These materials are highly heat resistant. This allows the infra-red heater to be placed in a mould used to cast the tube during manufacturing without becoming damaged by the hot material added to the mould to form the tube. In particular, ceramic or carbon fibre can be used when moulding a glass tube. Other embodiments may use any other suitable material for the infra-red heater.

[0021] In one particular example, the tube can comprise glass quartz and the infra-red heater can comprise a ceramic material. In another example, the tube can comprise glass or hardened glass and the infra-red heater can comprise carbon fibre.

[0022] Preferably, the infra-red heater is configured to emit radiation having a central wavelength between 2 and 10 pm. In this way, the infra-red heater mainly emits radiation at a wavelength that has been found to be effective at heating and penetrating the aerosol generating substance received in the cavity.

[0023] Preferably, the tube has a closed end and an open end for accessing the cavity. This arrangement may be more thermally efficient and easier to clean.

[0024] Preferably, the heating apparatus comprises an outer tube having an inner surface and an outer surface, the outer tube arranged around said tube such that the tube provides an inner tube to the outer tube; wherein a vacuum insulator is formed (or, in other words, a vacuum is present) between the outer surface of the inner tube and the inner surface of the outer tube. In this way, a vacuum can be arranged around the inner tube to insulate the cavity more effectively. A vacuum layer provides effective insulation at lower thicknesses compared to solid insulation layers. The use of an outer tube to enable a vacuum to be positioned about the inner tube can therefore reduce size of the heating apparatus as well as providing more effective insulation.

[0025] The outer tube surface stays cold as it is thermally insulated from the inner tube by the vacuum. The outer tube can be fixed in an aerosol generating device by any appropriate material to provide mechanical stability. The increased insulation provided by the vacuum can avoid the need for temperature resistant fixtures for holding the heating apparatus.

[0026] One or more support structures may be provided between the inner tube and the outer tube. In this way, the number of contact points between the inner and outer tube is increased to increase the robustness of the heating apparatus. The support structures may be an integral part of one of the inner or outer tubes. The support structures can be provided at any suitable location, such as between closed ends of the inner outer tubes or between peripheral walls of the inner and outer tubes at a plurality of spaced positions.

[0027] In the case where a vacuum is provided between outer and inner tubes, preferably, the infra-red heater is arranged longitudinally in the inner tube, for example in a winding or serpentine manner. This arrangement may be easier to manufacture because two electrodes for the infra-red heater can be arranged more easily at an open end of the inner tube to facilitate connection to a power source.

[0028] Preferably, each of the inner tube and the outer tube define an open end and a closed end, wherein the tubes are attached to one another at their open ends by a collar. The collar is preferably provided on the inner tube.

[0029] According to a further aspect of the present invention there is provided an aerosol generating device comprising the heating apparatus as previously disclosed.

[0030] Preferably, the aerosol generating device comprises a shock absorber configured to protect the tube against an impact. In this way, the tube can be made from a more fragile material, such as glass, while minimising the risk of damaging the glass through impacts to the aerosol generating device. The shock absorber can comprise foam or a spring-loaded support, in some examples. Any other suitable form of absorber could be used alternatively or in addition.

[0031] Preferably, the aerosol generating device is configured to heat a consumable comprising tobacco to temperatures below the combustion temperature of tobacco. In this way, the aerosol generating device can function as a heat-not- burn device, in which case the infra-red heater helps to provide penetrated heating, preferably directly to the centre of the consumable for faster heating.

[0032] According to a second aspect of the present invention there is provided a method of manufacturing a heating apparatus, comprising the steps of: placing an infra-red heater into a mould for forming a tube; and casting the tube using the mould such that the infra-red heater is embedded in the tube in a solid structure between an inner surface and an outer surface of the tube.

[0033] The method of manufacturing can be used to form the heating apparatus of the first aspect of the invention.

[0034] According to a third aspect of the present invention there is provided a heating assembly for an aerosol generating device configured to operate with an aerosol generating article, the heating assembly comprising: an inner tube having an inner surface and an outer surface, and defining a cavity positioned inwardly of the inner surface in which the aerosol generating article can be received; a heater embedded in the inner tube, between the inner surface and the outer surface, and configured to heat the aerosol generating article when it is received in the cavity; an outer tube having an inner surface and an outer surface, and arranged around the inner tube; wherein a vacuum insulator is formed between the outer surface of the inner tube and the inner surface of the outer tube.

[0035] The heating assembly may also be referred to interchangeably as a heating apparatus. The embodiments of the third aspect of the present invention may generally be combined with embodiments of the first and second aspects of the invention.

[0036] Preferably, the heater is an infra-red heater.

[0037] Preferably, the inner tube is substantially transparent to infra-red radiation.

[0038] Preferably, the heater comprises a carbon fibre wire extending in an internal space of the inner tube formed between its inner and outer surfaces.

[0039] Preferably, the heater is arranged longitudinally in the inner tube, for example in a serpentine manner. This arrangement may be easier to manufacture because two electrodes for the heater can be arranged more easily at the open end of the inner tube to facilitate connection to a power source.

[0040] Preferably, each of the inner and outer tubes defines an open end and a closed end; the tubes being attached one to the other on their open ends by a collar. More preferably, the collar is formed by the inner tube.

[0041] Preferably, the heater comprises a pair of contacts protruding from or forming at least partially an outer surface of the collar.

[0042] Preferably, the outer surface of the inner tube is at least partially coated with a reflective coating.

[0043] Preferably, the reflective coating is configured to reflect infra-red radiation.

[0044] The reflective coating may comprise at least one of copper, aluminium or silver. In other embodiments, the reflective coating may comprise any other suitable material, such as Cu-AI intermetallic materials.

[0045] Preferably, each of the inner and outer tubes are made from glass.

[0046] Preferably, the infra-red heater is present along 50-80% of the length of the tube along the longitudinal axis of the tube. This may provide an effective balance between efficiency and thorough heating. According to a further aspect of the invention there is provided a method of production of the heating assembly according to the third aspect of the invention, comprising the following steps: embedding a heater in the inner tube; arranging the inner tube inside the outer tube; and forming a vacuum insulator between the outer surface of the inner tube and the inner surface of the outer tube.

[0047] Preferably, the step of arranging the inner tube inside the outer tube comprises attaching the tubes at their open ends by glass fusion. This attaching step may be performed in a vacuum.

[0048] Preferably, the method further comprises a step of coating at least partially the outer surface of the inner tube to form a reflective coating.

[0049] Preferably, the step of coating is realized by evaporation, sputtering or submerging the inner tube into a melt material.

[0050] The outer tube may be preformed, e.g. by precision glass moulding (PGM) or any other suitable manufacturing method.

[0051] BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Embodiments of the invention are now described, by way of example, with reference to the drawings, in which:

[0053] Figure 1 shows a schematic cross-sectional diagram of an aerosol generating device according to an embodiment of the invention;

[0054] Figure 2 shows a schematic control diagram of the aerosol generating device in an embodiment of the invention;

[0055] Figure 3 shows a schematic perspective view of a heating apparatus in an embodiment of the invention;

[0056] Figure 4 shows cross sectional shapes for an infra-red heater in an embodiment of the invention; Figure 5 shows a schematic perspective view of a heating apparatus in an embodiment of the invention;

[0057] Figure 6 shows a schematic perspective view of a heating apparatus in an embodiment of the invention;

[0058] Figure 7 shows a method of manufacturing a heating apparatus in an embodiment of the invention;

[0059] Figure 8 shows a schematic cross-sectional diagram of a heating apparatus according to an embodiment of the invention;

[0060] Figure 9 shows a schematic cross-sectional diagram of a heating apparatus according to an embodiment of the invention;

[0061] Figure 10 shows a schematic perspective view of a heating apparatus in an embodiment of the invention;

[0062] Figure 11 shows a schematic cross-sectional diagram of a heating apparatus according to an embodiment of the invention;

[0063] Figure 12 shows a method of manufacturing a heating apparatus in an embodiment of the invention; and

[0064] Figure 13 shows a schematic cross-sectional diagram of a heating apparatus according to an embodiment of the invention.

[0065] DETAILED DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a cross-sectional schematic diagram of an aerosol generating device in an embodiment of the invention. An aerosol generating device 100 is provided and comprises an outer casing 102 for housing internal components of the aerosol generating device 100. The outer casing 102 comprises an opening 104 to a cavity 106. A heating apparatus 108 is provided in the cavity 106 and comprises a tube 110 with an inner wall 112 and an outer wall 114, between which an infra-red heater 116 is embedded in the solid material of the tube 110. The tube 110 comprises an opening 118 to an internal cavity 109. The opening 118 is aligned with the opening 104 in the outer casing 102 so that a consumable can be received in the cavity 109 of the tube 110. A battery 120 is provided within the outer casing 102 for providing electrical power to electronic components of the aerosol generating device 100, including the infra-red heater 116. The infra-red heater 116 is arranged to heat a consumable that is removably received within the tube 110 in response to an applied electric current from the battery 120. The tube 110 is substantially transparent to infra-red radiation to allow radiation emitted by the infra-red heater 116 to reach and heat the consumable.

[0067] Figure 2 shows a schematic control diagram of the aerosol generating device 100. A controller 122 is provided within the outer casing 102 of the aerosol generating device 100. The controller 122 comprises at least one processor 122a and a memory 122b for executing and storing executable instructions 122c, respectively. The instructions 122c include instructions for implementing various operations of the aerosol generating device 100. The controller 122 is configured to receive or send signals from the components shown in Figure 2 to control various operations of the aerosol generating device 100. A button 124 is provided on an outer surface of the outer casing 102 for enabling a user to initiate the infra-red heater 116.

[0068] In other embodiments, the button 124 can be any other suitable input mechanism configured to receive an input from the user that enables the controller 122 to initiate the infra-red heater 116 in response. Similarly, the battery 120 can be any suitable type of battery known in the art.

[0069] The aerosol generating device 100 can also comprise a sensor (not shown) configured to detect the insertion of a consumable in the cavity 109. The sensor can be of any suitable kind, such as an optical sensor or a mechanical sensor. In one example, the sensor may be arranged at the opening 104. The controller 122 may be configured to automatically turn on or initiate the infra-red-heater 116 in response to a detection of the consumable by the sensor. The consumable can also be of any suitable type known in the art and may contain any suitable aerosol generating substance. In one example, the consumable comprises tobacco and may also include a filter held together with the tobacco by a tipping wrapper. The consumable can be in the form of a stick sized for insertion into the cavity 109. Advantageously, the consumable defines a cylindrical shape, having for example a circular cross-section. The consumable may be configured for being heated in the tube 110 below the combustion temperature of tobacco.

[0070] The heating apparatus 108 is shown in more detail in Figure 3. Figure 3 shows a perspective view of the tube 110 and the infra-red heater 116 embedded therein.

[0071] As shown, the tube 110 is elongate along a longitudinal axis and has a substantially cylindrical shape with a circular cross section. A circular cross section may be preferable for receiving the consumable and cleaning the tube 110; however, in other embodiments, the tube 110 may have any other suitable cross-sectional shape, such as a square or octagonal cross-sectional shape. In the embodiment of Figure 3, the tube 110 has a closed end. In other embodiments, the tube 110 may have two open ends and may be provided with a separate stopper for closing the cavity 109.

[0072] The tube 110 comprises glass that is substantially transparent to infra-red radiation. The skilled person would appreciate that negligible amounts of infrared radiation may be absorbed by the tube 110, such as below 15%, 10%, 5%, or less. The glass may be hardened glass and may be coupled in the aerosol generating device 100 with a suitable shock absorber, such as foam or a spring- loaded support, to prevent cracking of the tube 110. In other embodiments, the tube 110 can comprise any other material that enables an infra-red heater embedded therein to heat a consumable received in the tube 110. For example, the tube 110 can alternatively comprise quartz glass, which is also substantially transparent to infra-red radiation and is known to be more durable than other types of glass. The infra-red heater 116 is embedded inside the tube 110 between the inner surface 112 and the outer surface 114 of the tube 110. The infra-red heater 116 is arranged helically inside the tube 110 about the longitudinal axis of the tube 110 between two electrodes 116a, 116b. The infra-red heater 116 can be connected to the battery 120 via the controller 122 and the electrodes 116a, 116b. This allows the controller 122 to control the amount of electrical power delivered to the infra-red heater 116 from the battery 120.

[0073] The electrodes 116a, 116b are shown in Figure 3 as embedded within the tube 110 at opposite ends of the tube 110. In other embodiments the electrodes 116a, 116b could be provided on the aerosol generating device 100, in which case opposing ends of the infra-red heater 116 protruding from the tube 110 can be connected to the electrodes 116a, 116b. Alternatively, the electrodes 116a, 116b could be embedded in other locations of the tube 110.

[0074] The infra-red heater 116 comprises a continuous carbon fibre wire in this example. In other embodiments, the infra-red heater 116 can comprise any other suitable material, such as a ceramic material, capable of emitting infra-red radiation in response to an electric current from the battery 120.

[0075] The infra-red heater 116 emits radiation in response to an electric current applied from the battery 120 via the electrodes 116a, 116b with a peak wavelength in the infra-red band. In this embodiment, the infra-red heater 116 emits radiation having a peak wavelength in the range of 2-10 microns. Shorter or longer wavelengths may be used in other embodiments. Different wavelengths can penetrate into a consumable to different degrees. Therefore, the peak wavelength may be selected based on the dimensions of the tube 110 and the infra-red heater 116. The infra-red heater 116 mainly emits in the infrared band so that the tube 110 absorbs a minimal amount of radiation from the infra-red heater 116, making the heating apparatus 108 highly efficient. Emitting mainly in the infra-red band can also be described as emitting with an intensity profile with a peak wavelength in the infra-red band. The helical arrangement of the infra-red heater 116 has a circular cross section in this example embodiment. In other words, the infra-red heater 116 is wound helically in approximate concentric circles. In other embodiments, the infra-red heater 116 can be arranged helically with a cross section of a different, noncircular shape to increase the surface area of the infrared heater 116 within the tube 110 with respect to a circular helical arrangement. This enables more infrared radiation to be generated so that the consumable can be heated faster. As shown in Figure 4, in other embodiments the infra-red heater 116 can be arranged helically with an octagonal cross section 126 or a star-shaped cross section 128. Figure 4 depicts one example of an 8-pointed star-shaped cross section 128. In other embodiments, the star-shaped cross section 128 could be a 4-pointed, 5-pointed, 6-pointed, or 7-pointed star.

[0076] As shown in Figure 5, the infra-red heater 116 can be arranged longitudinally in the tube 110. In this example, the carbon fibre wire is arranged in a serpentine manner such that the wire has several substantially straight sections parallel with the longitudinal axis of the tube 110. Other arrangements of the infra-red heater 116 can be implemented in other embodiments. In some embodiments, the infra-red heater 116 can comprise several independent portions which can for example be connected in parallel to the battery 120.

[0077] The infra-red heater 116 is shown in Figures 3 and 5 as present along substantially the full longitudinal length of the tube 108. In other embodiments, the infra-red heater 116 may instead be present along 50-80% of the tube 108.

[0078] Figure 6 shows a perspective view of the heating apparatus 108 having an optional wrapping 130. The wrapping 130 is provided to prevent the escape of heat from the tube 110 by conduction and radiation and comprises an insulator and a reflective layer. The wrapping 130 is wrapped circumferentially around the outer surface 114 of the tube 110. An end of the tube 110 is shown to be exposed in Figure 6; however, in practice the wrapping 130 may include an end panel configured to cover and insulate the closed end of the tube 110. The insulator can comprise any suitable insulating material, such as Microlite®, Q-Fiber®, or mineral wool, in order to inhibit the escape of heat from the tube 110 by conduction. As described further below, the insulator can also be a vacuum layer contained by an outer tube.

[0079] Microlite® is a lightweight, binderless insulating blanket for applications in which temperatures may reach up to 538°C. Q-Fiber® Felt is formed from silica fibres using a water deposition process. It is flexible, binderless, and possesses the thermophysical and chemical stability of pure amorphous silica. Q-Fiber® Felt offers high heat resistance, remaining effective up to 982°C for steady state applications.

[0080] The reflective layer of the wrapping 130 is configured to reflect infra-red radiation back into the tube 110 to increase the efficiency of the heating apparatus 108. The reflective layer can be coated onto the outer surface 114 of the tube 110 or provided on an inner surface of the insulator.

[0081] The reflective layer can comprise any suitable layer, such as a white paint coating, a polished aluminium layer or coating, or any other material that is reflective in the emitting wavelength range of the infra-red heater 116.

[0082] An example usage of the aerosol generating device 100 and the heating apparatus 108 will now be described.

[0083] The user can insert a consumable through the opening 104 into the cavity 109 of the tube 110. The user can then press the button 124 to initiate a vaping session. The controller 122 enables the battery 120 to provide electrical current to the infra-red heater 116, which generates infra-red radiation in response to the electrical current flowing between the electrodes 116a, 116b. The tube 110 is substantially transparent to infra-red radiation, enabling the radiation to pass through the tube 110 to be absorbed by the consumable. In cases where the wrapping 130 is present, infra-red radiation emitted towards the outer surface 114 is reflected back towards the cavity 109 of the tube 110. As the tube 110 heats by conduction from the heated consumable, the insulator of the wrapping 130 inhibits the escape of heat from the heating apparatus 108. This provides a highly efficient heating apparatus 108 that heats the consumable quickly to aerosol generating temperatures. The heating apparatus 108 has been found to heat the consumable to 350 degrees Celsius in about 2 seconds. The consumable generates an aerosol which can be inhaled by the user through a protruding end of the consumable.

[0084] The infra-red heater 116 is embedded in the tube 110, which prevents any movement or dislodging of the infra-red heater 116 over the lifetime of the aerosol generating device 100. Such movement can negatively affect the aerosol generation process and lead to inconsistent aerosol generation over the lifetime of a device.

[0085] Figure 7 shows a method 200 of manufacturing a heating apparatus. The method 200 can be used to manufacture the heating apparatus 108.

[0086] In step 202, an infra-red heater is placed into a mould for forming a tube. The mould can be any suitable kind known in the art and may be made of metal, in one example. The infra-red heater is preferably heat resistant so that that hot tube material does not damage the infra-red heater. In some examples, the infra-red heater can comprise carbon fibre or a ceramic material, both of which are heat resistant to temperatures well above the melting temperature of glass.

[0087] In step 204, the tube is cast in the mould while the infra-red heater is positioned within the mould. For example, molten tube material may be deposited in the mould so that the tube material envelopes the infra-red heater. Once the tube is cast, the infra-red heater is embedded between the inner and outer surfaces of the tube in solid material. This provides a convenient way of forming the tube and attaching the infra-red heater to the tube simultaneously, providing an efficient method of manufacture. The tube material is transparent to infra-red radiation so that the infra-red heater can transmit infra-red radiation to a cavity of the tube. In some examples, the tube can be made from glass or quartz glass. A number of optional subsequent steps may be implemented. A reflective layer as described previously can be deposited on or wrapped about an outer surface of the tube to contain any infra-red radiation within the tube. An insulating layer for reducing conductive thermal losses can also be wrapped and secure to the tube. If the tube comprises glass, the glass may be subjected to a hardening process.

[0088] Figure 8 shows a cross sectional schematic diagram of a heating apparatus 308 according to an alternative embodiment of the invention.

[0089] The heating apparatus 308 comprises an inner tube 310 and an outer tube 311. The inner tube 310 is substantially the same as the tube 110 of the heating apparatus 108. The inner tube 310 comprises glass that is substantially transparent to infra-red radiation. An infra-red heater 316 is embedded in the solid material of the inner tube 310 between its inner and outer surfaces to heat a consumable received within a cavity 309 of the inner tube 310, as described previously. A reflective layer 330 is provided on the outer surface of the inner tube 310 to reflect infra-red radiation emitted by the infra-red heater 316 back towards the cavity 309, as shown in Figure 9. The reflective layer 330 is deposited directly on the outer surface of the inner tube 310, which improves the reflection efficiency of the reflective layer 330.

[0090] The outer tube 311 is arranged around the inner tube 310 and a vacuum 331 is enclosed between the outer surface of the inner tube 310 and the inner surface of the outer tube 311 to provide insulation to the cavity 309. The outer tube 311 also comprises glass.

[0091] The inner tube 310 and the outer tube 311 both comprise an open end and a closed end, as shown in Figure 8. The inner tube 310 comprises a collar 317 at its open end. Electrodes 316a, which may also be referred to as contacts or electrical contacts, are provided in the collar 317 and are exposed to allow electrical connection with the infra-red heater 316. Figure 10 shows a perspective view of the heating apparatus 308 from above, showing the electrodes 316a in the collar 317. The outer tube 311 is attached to underside of the collar so that the inner tube 310 and the outer tube 311 are spaced apart to enclose the vacuum 331 . Figure 11 shows a schematic cross sectional diagram of the outer tube 311 being attached to the collar 317 of the inner tube 310 during manufacturing.

[0092] As described previously, the heater 316 can be any suitable infra-red heater. The heater 316 may be longitudinally arranged in the inner tube 310, for example in a winding or serpentine manner as shown in Figure 10, so that the electrodes 316a can be positioned at the open end of the heating apparatus 308 more easily. Similarly, any other suitable material can be used in place of glass for the inner tube 310 and the outer tube 311 , provided the inner tube 310 is substantially transparent to infra-red radiation. The reflective layer 330 can be any suitable layer, such as copper, aluminium, silver, or a Cu-AI intermetallic material.

[0093] The heating apparatus 308 is sufficiently thermally insulated by the vacuum 331 during use that a temperature resistant holder is not necessary to safely incorporate the heating apparatus 308 into an aerosol generating device. This makes the heating apparatus 308 more space efficient.

[0094] In other aerosol generating devices including a vacuum insulator and a heater positioned outside of a heating cavity, an airtight join to thread a wire into a vacuum space can be required to power a heater within the vacuum. Such airtight joins can be difficult to manufacture robustly to ensure the integrity of the vacuum is maintained over time. The heating apparatus 308 avoids the need for such an airtight join because the infra-red heater 316 is embedded in the inner tube 310 and has exposed electrodes 316a.

[0095] Figure 12 shows a flowchart of a method 400 of manufacturing a heating apparatus, such as the heating apparatus 308.

[0096] In step 402, an infra-red heater is embedded in an inner tube. The heater can be placed into a mould for forming the inner tube. The mould can be any suitable kind known in the art and may be made of metal, in one example. The infra-red heater is preferably heat resistant so that hot tube material does not damage the infra-red heater. In some examples, the infra-red heater can comprise carbon fibre or a ceramic material, both of which are heat resistant to temperatures well above the melting temperature of glass. The inner tube can be made of glass or quartz glass in some examples, as discussed previously.

[0097] The inner tube can be cast in the mould while the infra-red heater is positioned within the mould. For example, molten tube material may be deposited in the mould so that the inner tube material envelopes the infra-red heater. Once the inner tube is cast, the infra-red heater is embedded between the inner and outer surfaces of the inner tube in solid material.

[0098] In step 404, the inner tube is arranged inside an outer tube. The inner tube may be formed in step 402 having a collar to provide a surface for attaching the outer tube. The inner tube can be inserted into the outer tube, as shown in Figure 11. The outer tube can comprise the same or a different material as the inner tube.

[0099] In step 406, a vacuum insulator is formed between the inner and outer tubes. This can be implemented by performing glass fusion between the inner and outer tubes in a vacuum to enclose a vacuum between the tubes. In one example, an edge of the outer tube may be heated and melted, and a collar of the inner tube can be pressed against the melted portion in a vacuum to join the inner and outer tubes.

[0100] A number of further optional steps may be implemented. A reflective layer as described previously can be deposited about an outer surface of the inner tube prior to step 404. For example, thermal evaporation, sputtering, dip-coating in molten material, or any other suitable technology or method can be used to coat the outer surface of the inner tube with a reflective coating. Additionally, in this case, no vacuum insulator can be provided.

[0101] If the inner or outer tube comprises glass, the glass may be subjected to a hardening process. The outer tube can be pre-formed by any suitable method, such as by precision glass moulding. Figure 13 shows an optional support structure 340 that may be provided in the heating apparatus 308 between the inner tube 310 and the outer tube 311. The support structure 340 provides a further contact point between the inner tube 310 and the outer tube 311 , in addition to the contact point at the collar 317 indicated by the dotted lines (C). The support structure 340 increases the mechanical strength of the heating apparatus 308 and stabilises the inner tube 310 against the outer tube 311. In this example, the support structure 340 comprises a rib arranged between the closed ends of the inner tube 310 and the outer tube 311. In other examples, the support structure 340 can be positioned elsewhere in the heating apparatus 308.

[0102] The support structure 340 is formed from glass as integral part of one of the inner tube 310 and the outer tube 311. In other embodiments, the support structure 340 may be a separate component arranged in the space between the inner tube 310 and the outer tube 311. In other embodiments, a plurality of support structures 340 may be provided between the inner tube 310 and the outer tube 311 to increase the number of contact points.

Claims

CLAIMS1 . A heating apparatus for an aerosol generating device, comprising: a tube having an inner surface and an outer surface and defining a cavity positioned inwardly of the inner surface in which an aerosol forming substance can be received; and an infra-red heater embedded in the tube in a solid structure, between the inner surface and the outer surface, and configured to emit infra-red radiation to heat an aerosol generating substance received in the cavity; wherein the tube is substantially transparent to infra-red radiation to enable the transmission of infra-red radiation from the infra-red heater to the cavity.

2. The heating apparatus of claim 1 , further comprising a reflective layer provided on the outer surface of the tube.

3. The heating apparatus of claim 2, further comprising an insulator surrounding the reflective layer.

4. The heating apparatus of any of the preceding claims, wherein the infrared heater is arranged helically about a longitudinal axis of the tube or longitudinally along a longitudinal axis to form a serpentine shape.

5. The heating apparatus of any of the preceding claims, wherein the infrared heater has a cross sectional shape that is non-circular.

6. The heating apparatus of claim 5, wherein the infra-red heater has a substantially octagonal or star-shaped cross-sectional shape.

7. The heating apparatus of any of the preceding claims, wherein the tube comprises glass.

8. The heating apparatus of any of the preceding claims, wherein the infrared heater comprises ceramic or carbon fibre.

9. The heating apparatus of any of the preceding claims, wherein the solid structure is a solid material that forms the tube.

10. The heating apparatus of any of the preceding claims, further comprising an outer tube having an inner surface and an outer surface, the outer tube arranged around said tube such that the tube provides an inner tube; wherein a vacuum insulator is formed between the outer surface of the inner tube and the inner surface of the outer tube.

11. The heating apparatus of claim 10, wherein each of the inner tube and the outer tube define an open end and a closed end, wherein the tubes are attached to one another at their open ends by a collar.

12. An aerosol generating device comprising the heating apparatus of any of the preceding claims.

13. The aerosol generating device of claim 12, further comprising a shock absorber configured to protect the tube against an impact.

14. A method of manufacturing a heating apparatus, comprising the steps of: placing an infra-red heater into a mould for forming a tube; and casting the tube using the mould such that the infra-red heater is embedded in the tube in a solid structure between an inner surface and an outer surface of the tube; wherein the tube is substantially transparent to infra-red radiation to enable the transmission of infra-red radiation from the infra-red heater through the tube.

15. The method of manufacturing of claim 14, wherein the heating apparatus corresponds to the heating apparatus of any of claims 1 to 11 .

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