Aerosol Generating Device with a Vacuum Insulator

Description

FIELD OF INVENTION

The invention relates to aerosol generating devices. In particular, the invention relates to aerosol generating devices with a vacuum insulator.

BACKGROUND TO THE INVENTION

Aerosol generating devices can generate an aerosol by heating an aerosol forming substance using one or more heaters. Operating the heaters can be energy intensive, particularly in aerosol generating devices configured to heat tobacco in a heating oven. Such aerosol generating devices can also take several seconds to reach aerosol generation temperatures, which can be inconvenient for the user. There is therefore a demand for aerosol generating devices that are more efficient and can generate an aerosol more quickly. Additionally, there is a need to maintain the external surface of the aerosol generating device to safe and comfortable temperatures.

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

SUMMARY OF INVENTION

According to a first aspect of the invention there is provided an aerosol generating device, comprising: an insulator, comprising an inner wall and an outer wall that are separated from one another; a cavity defined within the inner wall in which an aerosol forming substance can be received; and a heater positioned to heat the aerosol forming substance when it is received in the cavity, wherein a reflective coating is provided on an outer surface of the inner wall.

In this way, the reflective coating can inhibit the radiative transfer of heat from the inner wall to the outer wall, thus providing a more thermally efficient aerosol generating device. The reduced escape of heat from the cavity enables the cavity to reach aerosol generating temperatures more quickly. The insulator also insulates an external surface of the aerosol generating device more effectively, reducing the temperature of the external surface during use. This provides a safer device that is more comfortable to hold.

The skilled person would appreciate that the terms “inner” and “outer” as used herein refer to the wall (or surface of a wall) closest or furthest, respectively, from the cavity.

Preferably, the inner wall and the outer wall are separated from one another by a vacuum. In this way, the insulator is a vacuum insulator and insulates the cavity more effectively. The use of reflective coatings with a vacuum insulator is particularly advantageous because a vacuum insulator is very effective at reducing heat transfer by conduction, but is less effective at reducing heat transfer by radiation. It is believed that the reflective coating can reduce the amount of heat that is radiated from the inner wall's outer surface.

In other example embodiments, the insulator can contain any suitable thermally insulating medium, such as air.

Preferably, the reflective coating is also provided on an inner surface of the outer wall. In this way, heat radiated from the inner wall can be reflected back towards the inner wall to inhibit the escape of heat from the insulator. This further improves efficiency of the aerosol generating device and reduces the temperature of the outer surface of the aerosol generating device. In addition, the reduced escape of heat from the cavity enables the cavity to reach aerosol generating temperatures more quickly.

Preferably, the heater is provided on the outer surface of the inner wall. In this way, the heater can efficiently deliver heat to the cavity by conduction through the inner wall.

The heater may be provided between the reflective coating and the inner wall. In this way, heat radiated from the surface of the heater towards the outer wall in the form of infra-red radiation is reflected back towards inner wall. This further improves the thermal efficiency of the aerosol generating device.

In some embodiments, the heater is provided on an inner surface of the inner wall. The reflective coating may be provided additionally on the inner surface of the inner wall and the heater can be provided on the reflective coating of the inner surface of the inner wall.

In other embodiments, the heater can be any form of heater arranged to heat the aerosol generating substance received in the cavity as known in the art. For example, the heater can comprise an inductively or resistively heatable blade or rod positioned in the cavity to heat the aerosol generating substance. The blade or rod may be configured to penetrate a consumable containing the aerosol generating substance. Alternatively, the heater can include an induction arrangement configured to inductively heat one or more induction elements or susceptors. The induction elements can be provided about a periphery of the cavity. Alternatively, the induction element or elements could be provided inside a consumable that is receivable within the cavity.

Preferably, the reflective coating comprises a layer of reflective paint. In one example, a high reflectivity white paint can be used. The use of white paint has been found to reduce the outer surface of the inner wall to 151° C. in use. In another example, silver paint can be used.

Preferably, the reflective coating comprises a layer of metal foil, such as aluminium foil. Alternatively, silver foil can be used, which has been found to reduce the outer surface of the inner wall to 135° C. in use.

The reflective coating can also comprise a vapour-deposited metal layer, such as vapour-deposited silver, gold, or aluminium.

Preferably, the reflective coating comprises a first layer and a second layer. The first layer and the second layer can comprise different materials. This may provide a more effective means of insulating the outer wall from radiant heat. For example, the first and second layers may comprise different materials and thus may have reflectance profiles that peak at different wavelengths so that radiation can be reflected efficiently across a broader range of wavelengths.

Preferably, the first layer comprises a reflective paint and the second layer comprises metal foil. This may provide a more effective means of insulating the outer wall from radiant heat. In one example, the paint can be a reflective white paint and the metal foil can be aluminium. This particular combination has been found to reduce the outer surface of the inner wall to 107° C. in use.

Preferably, the aerosol generating device is configured to heat an aerosol generating substance comprising tobacco. The heater may be configured to heat the cavity to temperatures below the combustion temperature of tobacco and the cavity may be configured to receive a rod or elongated consumable comprising tobacco. This allows the aerosol generating device to function as a heat-not-burn device.

In some embodiments, the reflective coating may also be provided on the outer wall. In this way, the efficiency of the insulator can be further improved. The reflective coating can be provided on the inner surface or the outer surface of the outer wall. Alternatively, the coating can be provided on both of the inner and outer surfaces of the outer wall.

According to a second aspect of the invention there is provided an aerosol generating device, comprising: an insulator, comprising an inner wall and an outer wall that are separated from one another; a cavity defined within the inner wall in which an aerosol forming substance can be received; and a heater positioned to heat the aerosol forming substance when it is received in the cavity, wherein a reflective coating is provided on the outer wall.

In this way, heat radiated from the inner wall can be reflected back towards the inner wall to inhibit the escape of heat from the insulator. This further improves efficiency of the aerosol generating device and reduces the temperature of the outer surface of the aerosol generating device. In addition, the reduced escape of heat from the cavity enables the cavity to reach aerosol generating temperatures more quickly.

The second aspect of the invention can include any of the features discussed in relation to the first aspect of the invention above, such as the insulator being a vacuum insulator and/or the specific reflective coatings.

BRIEF DESCRIPTION OF THE DRAWINGS

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

FIG. 1 shows a schematic cross-sectional diagram of an aerosol generating device according to an embodiment of the invention;

FIG. 2 shows a schematic control diagram of an aerosol generating device according to an embodiment of the invention;

FIG. 3 shows a schematic cross-sectional diagram of a heating apparatus in use according to an embodiment of the invention;

FIG. 4 shows a schematic diagram of a portion of a heating apparatus according to an embodiment of the invention;

FIG. 5 shows a schematic plan view of a heating apparatus according to an embodiment of the invention; and

FIG. 6 shows a schematic diagram of a portion of a heating apparatus according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of an aerosol generating device 100 according to an embodiment of the invention.

The aerosol generating device 100 comprises a tubular housing 102 for containing and protecting the internal components of the aerosol generating device 100. A vacuum insulator 103 is provided and comprises an inner wall 104, an outer wall 106, and an annular vacuum 108 separating the two, and enclosed by the inner wall 104 and the outer wall 106. As discussed further below with reference to FIGS. 4 and 6, the vacuum insulator 103 comprises a reflective coating to improve the insulation properties of the vacuum insulator 103. A cavity 110 is defined within the inner wall 104 for receiving an aerosol forming substance. An opening 111 is provided on the housing 102 and is aligned with the cavity 110 to enable a user to insert the aerosol forming substance into the cavity 110. A heater 112 is provided on the inner wall 104 and within the vacuum 108 for heating the aerosol forming substance received in the cavity 110 by conduction through the inner wall 104.

A controller 114 is provided and is configured to control the operation of the heater 112. A button 116 is provided on the housing 102 in electrical connection with the controller 114 for enabling a user to initiate aerosol generation. A battery 118 is provided for providing power to the heater 112, the controller 114, and any other electric components of the aerosol generating device 100.

FIG. 2 shows a schematic control diagram of the aerosol generating device 100. The controller 114 comprises at least one processor 114a and a memory 114b for executing and storing, respectively, executable instructions 114c for operating the components of the aerosol generating device 100. The controller 114 is electrically connected to the components shown in FIG. 2 to receive or send operational signals.

The housing 102 may comprise any suitable material known in the art, such as plastic or metal. In other embodiments, the button 116 can be replaced with or used alongside any other suitable input mechanism, such as a fingerprint sensor or a gesture sensor. The battery 118 may be permanently fixed within the housing 102 and rechargeable. Alternatively, the battery 118 may be removable. In other embodiments, the aerosol generating device may be provided without a battery 118 and the user may supply a separate battery pack or disposable power source.

As shown in FIG. 3, the vacuum insulator 103, the heater 112 and the cavity 110 form a heating apparatus 120. A rod-shaped consumable 10 comprising tobacco 12 and a filter 14 is shown inserted into the cavity 110, as would be performed by the user prior to use of the aerosol generating device 100.

The heater 112 is provided inside the vacuum 108 at two separate positions on diametrically opposing portions of the inner wall 104. The heater 112 comprises resistive tracks configured to generate heat when provided with an electric current, and these tracks are disposed on a film substrate which serves as an electrically insulating substrate. The film heater is curved to match the curvature of the inner wall 104 to enable good thermal contact with the inner wall 104. In alternative embodiments, the heater 112 may be provided as any suitable heater that can heat the consumable 10 within the cavity 110 to generate an aerosol. The heater 112 can be provided as one or more curved heating films or tracks that extend around the circumference of the inner wall 104. Alternatively, the heater 112 may be provided as one or more heating films or tracks provided at spaced positions around the inner wall.

The heater 112 is configured to heat the inner wall 104 by conduction to raise the temperature of air in the cavity 110 to aerosol generating temperatures. The consumable 10 may have a circumference substantially matching the circumference of the cavity 110 so that the consumable 10 is in contact with the inner wall 104 when it is placed into the cavity 110 by a user. The heater 112 heats the contents of the cavity 110 to a temperature sufficient to generate an aerosol using the tobacco 12 inside the consumable 10. The heater 112 may be configured to heat the contents of the cavity 110 to temperatures below the combustion temperature of the tobacco 12, enabling the aerosol generating device 100 to function as a so-called “heat-not-burn” device.

In other embodiments, the cavity 110 and the heater 112 may be configured to receive and heat, respectively, other forms of consumables as is known in the art. For example, the heater 112 can include an inductively heatable susceptor material configured to generate heat under the influence of electromagnetic fields. Such electromagnetic fields can be generated by an inductor unit provided at a suitable location in the aerosol generating device 100. Alternatively, the susceptor material may be permanently located within the cavity 110 or may be provided inside the consumable 10. The heater 112 can also take the form of a resistively or inductively heatable rod or blade positioned within the cavity 110 to penetrate the consumable 10.

The vacuum insulator 103 of FIG. 1 has an annular cylindrical shape with a circular cross-section. The vacuum insulator 103 is hollow and encloses a vacuum 108 between a curved inner wall 104, a curved outer wall 106, and substantially flat surfaces 122a-122c that close vacuum 108 within the inner wall 104 and the outer wall 106. The flat surface 122a connects the inner wall 104 to the outer wall 106, while the flat surfaces 122b, 122c close the inner wall 104 and the outer wall 106, respectively.

In other embodiments, the vacuum insulator 103 may have other shapes. For example, the vacuum insulator 103 may have a square or polygonal cross-section, or any other suitable cross-sectional shape. The vacuum insulator 103 shown in FIGS. 1 and 3 has a cup shape with one open end and one closed end; however, the vacuum insulator 103 may also have a tubular shape with two open ends. In another example, the outer wall 106 may be joined directly to the inner wall 104 without the connecting flat surface 122a as shown in FIG. 3. The vacuum insulator 103 may be mechanically attached to the housing 102 by one or more mechanical couplings (not shown). The vacuum insulator 103 may comprise stainless steel, heat resistant plastic such as PEEK, or any other suitable materials.

The heater 112, inner wall 104 and the flat surface 122b collectively heat the consumable 10 by conduction and can thus also be referred to collectively as a “heater cup”. The outer wall 106 and the flat surface 122c enclose the vacuum 108 around the heater cup and thus can also be referred to as the “outer shell” or “vacuum chamber” of the heater cup. The heater cup and the outer shell can comprise different materials. For example, the inner wall 104 and flat surface 122b can comprise a metal such as stainless steel, while the outer wall 106 and flat surface 122c can comprise an insulator, such as heat-resistant glass. The inner and outer walls 104, 106 can comprise any suitable materials known in the art. The flat surface 122a can be integrated with the heater cup or the outer shell, or can be provided as a separate component joined to the inner and outer walls 104, 106.

In other example embodiments, the vacuum insulator 103 may be replaced with other types of insulators. In one example an insulator can be provided comprising an inner wall and an outer wall containing an insulating medium, such as air, aerogel, and various foamed or fibrous materials, rather than a vacuum 108.

An example use of the aerosol generating device 100 will now be described with reference to FIG. 1. In use, a user can insert the consumable 10 through the opening 111 into the cavity 110. The inner wall 104 holds the consumable 10 in place within the cavity 110 by friction. When the user is ready to initiate vaporisation, the user may press the button 116, which in turn triggers the controller 114 to turn on the heater 112. The heater 112 provides heating to the contents of the cavity 110, including the consumable 10, while the vacuum 108 within the vacuum insulator 103 inhibits the escape of heat from the cavity 110. Thus, the heating apparatus 120 forms an oven in which the tobacco 12 within the consumable 10 can be heated to a desired temperature. The controller 114 may be configured to instruct the heater 112 to heat the tobacco 12 to temperatures below the combustion temperature of tobacco. As the tobacco 12 is heated, an aerosol is produced inside the cavity 110. The user can inhale the aerosol by drawing air through the filter 14 to generate an airflow through the consumable 10 which carries the aerosol to the user.

FIG. 4 shows a cross-sectional portion of the heating apparatus 120 according to an embodiment of the invention. The inner wall 104 comprises an inner surface 104a facing the cavity 110 and an outer surface 104b facing the vacuum 108. Similarly, the outer wall 106 comprises an inner surface 106a facing the vacuum 108 and an outer surface 106b facing the housing 102. FIG. 5 shows a plan view of the heating apparatus 120 to illustrate the different surfaces of the inner and outer walls 104, 106 from a different perspective.

During use, the heater 112 heats the inner wall 104 to temperatures generally above 100° C. The consumable 10 is in contact with the inner surface 104a and thus the consumable 10 is heated by conduction. The inner surface 104a also emits radiation, or “radiant heat”, which can become absorbed by the consumable 10 to further heat the consumable 10. However, the outer surface 104b of the inner wall 104 can, undesirably, also emit radiant heat towards the outer wall 106. This radiation can become absorbed by the outer wall 106 and subsequently lost from the vacuum insulator 103 by conduction or radiation processes. The present invention provides a first reflective coating 124 on the outer surface 104b, as shown in FIG. 4, to minimise the loss of heat from the vacuum insulator 103 in this way.

The first reflective coating 124 can reflect radiation received from the outer surface 104b. Additionally, the reflective coating 124 can inhibit the emission of radiation from the outer surface 104b. This provides a more efficient insulator for an aerosol generating device 100. Additionally, the consumable 10 reaches aerosol generating temperatures more quickly because less heat can escape from the cavity 110.

In the embodiment of FIGS. 1-5 the first reflective coating 124 is provided on all of the inner wall 104 and the flat surface 122b (i.e., on all of the “heater cup”). In other embodiments, the first reflective coating 124 can be provided on only some of the inner wall 104, for example only on the parts of the inner wall 104 and flat surface 122b exposed to the vacuum 108. In a further embodiment shown in FIG. 6, the first reflective coating 124 can be provided over the heater 112 such that the heater 112 is enclosed between the first reflective coating 124 and the inner wall 104. This can inhibit emission from the heater 112 towards the inner surface 106a of the outer wall 106, further improving efficiency and reducing the heating time for the consumable 10.

A second reflective coating 126 is also provided on the inner surface 106a of the outer wall 106. The second reflective coating 126 reflects radiation that reaches the outer wall 106 (despite the first reflective coating 124) back towards the cavity 110. This further improves efficiency and reduces the heating time for the consumable 10.

The second reflective coating 126 can similarly be provided on some or all of the inner wall 106 and flat surface 122c (i.e., the “outer shell”). The second reflective coating 126 can comprise the same or different materials from the first reflective coating 124. In other embodiments, only one of the first reflective coating 124 and the second reflective coating 126 are provided.

The first reflective coating 124 and the second reflective coating 126 can comprise any suitable material. Some example materials that can be used include: paints, such as white, silver or other metallic paints; metals, such as metal foils including silver, aluminium and gold; vapour-deposited metal layers, such as vapour-deposited silver, aluminium or gold; or glazes, such as a Heraeus overglaze. Metal layers may be provided with an oxide protection layer; however, this may not be required in the vacuum insulator 103. Reflectivity properties of gold, silver and aluminium for various wavelengths are shown below in Table 1. The first reflective coating 124 and/or the second reflective coating 126 can have at least the levels of reflectivity shown in Table 1 when comprising the corresponding material.

The first reflective coating 124 and/or the second reflective coating 126 can also comprise a first layer having a first material and a second layer having a second material. In one example, the first reflective coating 124 can comprise a white paint coated onto the outer surface 104b and an aluminium foil wrapped over or under the heater 112 about the outer surface 104b. In other examples, any combination of two or more materials discussed above can be used in the first or second reflective coating 124, 126.

Table 2 shows the temperature of the outer surface 104b when the heater is turned on for different material choices for the first reflective coating 124. As shown, the combination of white paint and aluminium foil was found to be particularly effective at reducing the temperature of the outer surface 104b (and thus also reducing the radiative transfer of heat to the outer wall 106).

In some embodiments, a reflective coating may also be provided on the outer surface 106b of the outer wall 106 to further insulate the cavity 110. The outer surface 106b may be coated with any of the materials discussed above in relation the first or second reflective coatings 124, 126.

In a further embodiment, a reflective coating may be provided on the inner surface 104a in addition to the outer surface 104b. In this case, the heater 112 is positioned on the inner surface 104a over the reflective coating of the inner surface 104a, instead of being positioned on the outer surface 104b within the vacuum 108.