Aerosol generator with vacuum insulation

Abstract

An aerosol generating device (100) is disclosed, comprising: a vacuum insulator (110) having an inner wall (112) and an outer wall (114) with a vacuum (116) enclosed therebetween; a cavity (106) capable of receiving an aerosol-forming substance (12), the cavity (106) being disposed adjacent to the inner wall of the vacuum insulator and having an opening (104) that allows a user to insert the aerosol-forming substance into the cavity; a heater (108) disposed in thermal contact with the inner wall and configured to heat the aerosol-forming substance received in the cavity by thermal conduction to generate an aerosol; and a thermal bridge (118) disposed between the inner and outer walls to provide a path for heat conduction, the thermal bridge being disposed in the vacuum between a first end (120) of the vacuum insulator closest to the opening and the heater, allowing heat to be transferred from the inner wall to the outer wall by conduction.

Description

[Technical Field]

[0001] The present invention relates to an aerosol generating device, and more particularly to an aerosol generating device having vacuum insulation. [Background technology]

[0002] An aerosol generating device may include a heater and vacuum insulation that insulates the heater from the external environment. Openings in the vacuum insulation can result in heat loss, reducing the thermal efficiency of the device and posing a potential safety risk to users if the openings reach a sufficiently high temperature. Therefore, there is a need for safer and more efficient aerosol generating devices. There is also a need for solutions that are compatible with existing aerosol generating device designs, as well as for more convenient and compact aerosol generating devices.

[0003] The object of the present invention is to meet these needs. Summary of the Invention [Means for solving the problem]

[0004] According to an aspect of the present invention, there is provided an aerosol generating device configured to generate an aerosol for inhalation by a user, the aerosol generating device comprising: a vacuum insulator having an inner wall and an outer wall with a vacuum sealed therebetween; a cavity capable of receiving an aerosol-forming substance, the cavity being positioned adjacent to the inner wall of the vacuum insulator and having an opening that allows a user to insert the aerosol-forming substance into the cavity; a heater being in thermal contact with the inner wall and configured to heat the aerosol-forming substance received in the cavity by thermal conduction to generate an aerosol; and a thermal bridge being positioned between the inner wall and the outer wall and providing a path for heat conduction, the thermal bridge being positioned in a vacuum between a first end of the vacuum insulator closest to the opening and the heater, allowing heat to be transferred from the inner wall to the outer wall by conduction.

[0005] In aerosol generators with vacuum insulation, a significant amount of heat from the heater can flow along the inner wall toward the opening through which the consumable can be inserted. This can cause the edge of the vacuum insulation closest to the opening to reach a high temperature. This has been found to allow heat to escape from the aerosol generator. The present invention employs a thermal bridge established in a vacuum between the heater and the first end between the inner and outer walls of the vacuum insulation. In this manner, the thermal bridge allows heat to flow along the inner wall to the outer wall, allowing some of the heat to flow away through the first end. This can reduce the maximum operating temperature of the first end during use, thereby improving the efficiency of the device. This can also improve the safety of the device by reducing the temperature of components that a user may accidentally touch. Advantageously, by providing a thermal bridge inside the vacuum insulation, changes to the outer shape or dimensions of the vacuum insulation are avoided, making the solution of the present invention compatible with existing aerosol generator designs.

[0006] The thermal bridge is provided "in a vacuum", i.e., within the vacuum insulation between the inner and outer walls that enclose the vacuum. The thermal bridge may be completely or substantially surrounded by the vacuum.

[0007] The thermal bridge may comprise any suitable connecting structure that allows heat to flow from the inner wall to the outer wall. In one example, the thermal bridge may comprise one or more rigid struts or ribs. In another example, the thermal bridge may comprise one or more heat conducting wires.

[0008] Preferably, the thermal bridge is positioned on the inner wall longitudinally between the heater and the first end of the vacuum insulation. In other words, the thermal bridge is positioned at a circumferential position on the inner wall toward the first end, generally "above" the heater or in line with the heater. In this manner, the thermal bridge can be positioned near or along the most direct path along the inner wall from the heater to the first end, allowing for more effective redirection of heat toward the outer wall. In other embodiments, the thermal bridge may be positioned at other circumferential positions on the inner wall.

[0009] Preferably, the thermal bridge is provided on the inner wall at a position spaced at least 1 mm from the heater toward the first end. In this manner, the thermal bridge can avoid allowing excessive heat to flow to the outer wall, which could reduce the thermal efficiency of the device. The thermal bridge can be spaced 1 mm, 1.5 mm, 2 mm, 5 mm, or any other suitable distance from the heater.

[0010] Preferably, the location of the thermal bridge on the inner wall is selected to maintain the outer surface of the aerosol generating device adjacent to the first end of the vacuum insulation at or below 48°C during heater use. In this manner, the outer surface of the aerosol generating device adjacent to the first end can be maintained at a safe and thermally efficient temperature. The outer surface may be a housing or outer casing configured to contain and protect the components of the aerosol generating device. The thermal bridge may be positioned based on testing different distances from the heater while the heater is on and in use. The specific placement on the inner wall may depend on the specific design and operating parameters of the aerosol generating device. One skilled in the art will appreciate that the placement, length, thickness, material, and / or structure of the thermal bridge may be adjusted in various ways to maintain a temperature of 48°C during heater use.

[0011] Preferably, the heater is provided on the inner wall in the vacuum. In this way, the heater can be more effectively insulated from the external environment. Alternatively, the heater can be provided on the inner wall outside the vacuum (e.g., on the inner surface of the inner wall).

[0012] Preferably, the thermal bridge comprises a metal such as stainless steel, although in other embodiments the thermal bridge may comprise any other suitable thermally conductive material such as copper or ceramic.

[0013] Preferably, the thermal bridges provide structural support to the inner and outer walls. Thus, the thermal bridges may comprise a rigid structure. In this way, the vacuum insulation can be made more robust. This extra robustness can allow the inner and outer walls to be thinner, which has been shown to improve heating efficiency and the speed at which the aerosol-generating material reaches its optimum temperature. Thinner inner and outer walls also allow the vacuum insulation to be more compact, thereby improving the convenience of the device for users.

[0014] In some embodiments, the thermal bridge comprises one or more ribs disposed at circumferentially spaced locations on the inner wall, for example, the thermal bridge may comprise two, three, four or more ribs or struts evenly or irregularly spaced around the inner wall.

[0015] In some embodiments, the thermal bridge is configured to separate a first portion of the vacuum from a second portion of the vacuum. For example, the thermal bridge may include a surface with a vacuum disposed adjacent both sides of the surface such that the surface completely isolates the two portions of the vacuum from each other. In this manner, thermal isolation of the first end can be improved. In one example, the thermal bridge may include an annular connecting surface.

[0016] Preferably, the aerosol generating device further comprises a plurality of heaters and a plurality of thermal bridges, each thermal bridge being longitudinally disposed between a respective heater and the first end of the vacuum insulation material. In this manner, the use of the plurality of thermal bridges can achieve more uniform heating of the aerosol-forming material while reducing the maximum temperature of the first end during use.

[0017] Preferably, the vacuum insulation material has a closed second end opposite the first end. The closed second end may be more effective at insulating the remaining components of the aerosol generating device from the heater than the open first end. In this case, the thermal bridge is most effectively positioned by providing a thermal bridge between the first end and the heater. In one example, the inner wall and the outer wall may each have a substantially U-shaped cross section joined to each other only at the first end.

[0018] In other embodiments, both the first end and the second end may be open, such that the vacuum insulation is substantially tubular in shape. [Brief explanation of the drawings]

[0019] Embodiments of the present invention will now be described, by way of example, with reference to the drawings, in which:

[0020] [Figure 1] 1 is a cross-sectional schematic view of an aerosol generating device according to an embodiment of the present invention. [Figure 2] 1 is a plan view of a vacuum insulator according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional schematic view of a portion of a vacuum insulator according to an embodiment of the present invention. [Figure 4] 1 is a schematic diagram of a portion of a vacuum insulator according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] FIG. 1 is a cross-sectional schematic diagram of an aerosol generating device according to an embodiment of the present invention. An aerosol generating device 100 is provided, comprising an outer casing 102 for housing the internal components of the aerosol generating device 100. The outer casing 102 has an opening 104 to a cavity 106 configured to receive a consumable product 10. The consumable product 10 includes a tobacco 12 and a filter 14, both of which may be held together by a tipping wrapper 16. A vacuum insulator 110 is provided, having an annular cylindrical shape with an inner wall 112 and an outer wall 114, with a vacuum 116 enclosed therebetween. A heater 108 is disposed in the vacuum 116 on the outer surface of the inner wall 114 and configured to provide heating to the consumable product 10 when received in the cavity 106 to generate an aerosol. A thermal bridge 118 is disposed in the vacuum 116 between the heater 108 and a first end 120 of the vacuum insulator 110 closest to the opening 104. The thermal bridge 118 provides a path for heat to flow from the inner wall 112 to the outer wall 114 to reduce the temperature of the first end 120 of the vacuum insulation 110 during use.

[0022] The aerosol generating device 100 also includes a controller (not shown) for controlling the operation of the aerosol generating device 100, buttons (not shown) for receiving instructions from a user, an air inlet (not shown) in fluid communication with the cavity 106, and a battery (not shown) for powering the aerosol generating device 100. The controller and battery are in electrical communication with the buttons and heater 108 via wires (not shown).

[0023] The outer casing 102 may comprise any suitable material as known in the art, such as metal or plastic. As shown in Figure 1, the aerosol generating device 100, the vacuum insulation 110, and the cavity 106 may be elongated along their length.

[0024] In the embodiment of FIG. 1 , the heater 108 is provided within the vacuum 116 at two separate locations on circumferentially opposed portions of the inner wall 112. The heater 108 comprises two resistive film heaters configured to generate heat when an electric current is applied. The film heaters are curved to match the curvature of the inner wall 112 to enable good thermal contact with the inner wall 112. In alternative embodiments, the heater 108 may be provided as any suitable heater capable of heating the consumable 10 within the cavity 106 to generate an aerosol. In other examples, the heater 108 may be provided outside the vacuum 116, such as around the periphery of the cavity 106. The heater 108 may be provided as one or more curved heating films or tracks extending around the periphery of the inner wall 112. Alternatively, the heater 108 may be provided as one or more heating films or tracks provided at spaced locations around the inner wall.

[0025] The heater 108 is configured to heat the inner wall 112 by conduction, thereby raising the temperature of the air within the cavity 106 to an aerosol-generating temperature. The consumable 10 may have a circumference that substantially matches the circumference of the cavity 106, such that the consumable 10 contacts the inner wall 112 when placed within the cavity 106 by a user. The heater 108 heats the contents of the cavity 106 to a temperature sufficient to generate an aerosol using the tobacco 12 within the consumable 10. The heater 108 may be configured to heat the contents of the cavity 106 to a temperature below the combustion temperature of the tobacco 12, allowing the aerosol-generating device 100 to function as a so-called "heat-no-combustion" aerosol-generating device.

[0026] In other embodiments, cavity 106 and heater 108 may be configured to receive and heat other forms of consumables, respectively, known in the art. For example, cavity 106 may be configured to receive a consumable cartridge including a reservoir containing an aerosol-generating fluid, and heater 108 may be configured to provide heating to the consumable when received in cavity 106. In such cases, vacuum insulation 110 and cavity 106 may be appropriately shaped to allow the cartridge to be received within cavity 106, heated by heater 108, and insulated by vacuum insulation 110.

[0027] The vacuum insulation 110 in FIG. 1 has an annular cylindrical shape with a circular cross-section. The vacuum insulation 110 is hollow and contains a vacuum 116 between a curved inner wall 112, a curved outer wall 114, and two flat surfaces 115 connecting the inner wall 112 and the inner wall 114. In other embodiments, the vacuum insulation 110 may have other shapes. For example, the vacuum insulation 110 may have a square or polygonal cross-section or any other suitable cross-sectional shape. While the vacuum insulation 110 in FIG. 1 has a tubular shape with two open ends, the vacuum insulation 110 may also have a cup-shaped cross-section with only one open end. In another example, as shown in FIG. 3, the outer wall 114 may be directly bonded to the inner wall 112 without providing a connecting flat surface 115 at the first end 120 of the vacuum insulation 110. The vacuum insulation 110 may be mechanically attached to the outer casing 102 by one or more mechanical bonds (not shown). The vacuum insulation 110 may comprise stainless steel, a heat resistant plastic such as PEEK, or any other suitable material.

[0028] The controller may be housed within the outer casing 102 and includes a memory and a processor for storing and executing instructions for controlling various operations of the aerosol generating device 100. An air inlet may be provided as an opening in the outer casing 102 toward the second end 122 of the aerosol generating device 100 to allow a user to draw air through the cavity 106 via the filter 14. A button may also be provided on the exterior surface of the outer casing 102 to receive input from a user. Alternatively, any other input mechanism, such as a fingerprint or airflow sensor, may be provided to receive input from a user.

[0029] 1-3, the thermal bridge 118 comprises two straight, rigid ribs or struts connecting the inner wall 112 and the outer wall 114, with each rib or strut positioned directly between a respective heating plate of the heater 108 and a first end 120 of the vacuum insulation 110. A top view of the vacuum insulation 110 from above the first end 120 is shown in FIG. 2, showing two ribs with opposing circumferential positions on the inner wall 112. In other embodiments, the ribs can be positioned at other circumferential positions on the inner wall 112. The rigidity of the ribs can provide structural support to the inner wall 112 and the outer wall 114.

[0030] The thermal bridges 118 may comprise any suitable material for allowing heat to flow from the inner wall 112 to the outer wall 114, such as stainless steel, copper, other metals, or non-metallic materials. Additional or fewer ribs may be provided in other embodiments of the invention. The ribs or struts may be evenly spaced or irregularly positioned on the inner wall 112. The thermal bridges 118 may also comprise other types of structures suitable for allowing heat to flow by conduction from the inner wall 112 to the outer wall 114.

[0031] An example of use of the aerosol generating device 100 will now be described with reference to FIG. 1 . During use, a user can insert the consumable 10 into the cavity 106 through the opening 104. The inner wall 112 holds the consumable 10 in place within the cavity 106 by friction. This contact between the inner wall 112 and the consumable 10 also increases the efficiency with which heat is delivered to the tobacco 12 within the consumable 10. When the user is ready to begin vaporization, the user can press a button, which triggers the controller to turn on the heater 108. The heater 108 provides heating to the contents of the cavity 106, including the consumable 10, while the vacuum 116 within the vacuum insulation 110 prevents heat from escaping the cavity 106 by conduction and convection. Thus, the cavity 106, heater 108, and vacuum insulation 110 form an oven that can heat the tobacco 12 within the consumable 10 to a desired temperature. The controller may be configured to direct the heater 108 to heat the tobacco 12 to a temperature below the combustion temperature of the tobacco. As the tobacco 12 heats, an aerosol is generated within the cavity 106. A user can inhale the aerosol by drawing air through the air inlet, through the filter 14, and generating an airflow through the cavity 106 that carries the aerosol to the user.

[0032] It has been found that in similar known aerosol generators, the edge of the vacuum insulation closest to the opening to the cavity can reach undesirably high temperatures during use of the aerosol generator. This edge is in contact with the air in the cavity, which is heated by the high-temperature walls of the vacuum insulation. The heated air can be carried out of the cavity by airflow caused by the user or by air passing through the opening. This can carry heat out of the cavity, thereby reducing the efficiency of the aerosol generator. The high temperature at the exposed edge of the vacuum insulation can also heat the exterior surface of the outer casing 102 to high temperatures, which can pose a safety risk.

[0033] The aerosol generating device 100 of the present invention utilizes thermal bridges 118 to alleviate these problems. Figure 3 shows a schematic diagram of a portion of a cross section of the vacuum insulation 110 while the heater 108 is operating. Figure 3 shows schematic arrows 1-5 indicating the flow of heat by conduction within the vacuum insulation 110. While the heater 108 is on, a first portion 1 of heat flows from the heater 108 along the inner wall 112 toward the first end 120. A second portion 2 of heat, a fraction of the first portion 1, flows along the thermal bridge 118 to the outer wall 114. The remaining fraction 3 of the first portion 1 flows toward the first end 120. The second portion 2 reaches the outer wall 114, diffuses across the entire surface of the outer wall 114, and spreads in different directions as at least fourth and fifth portions 4 and 5 of heat. As shown, at least the fourth portion 4 is diverted away from the first end 120, thereby reducing the operating temperature of the first end 120 of the vacuum insulation 110 during use.

[0034] For the fifth portion 5 of heat, the conduction path length from the heater 108 to the first end 120 of the vacuum insulation 110 is increased by the thermal bridge 118. Increasing the conduction path length allows more time for the heat to be carried away from the first end 120 by radiation or other processes. Thus, increasing the heat path length to the first end 120 reduces the amount of heat that reaches the first end 120 by conduction.

[0035] During use, the temperature of the inner wall 112 increases as it approaches the heater 108. Because the second portion 2 is a fraction of the first portion 1, the thermal bridge 118 can therefore divert more or less heat to the outer wall 114 depending on its proximity to the heater 108. A spacing of 1 mm or more from the heater 108 toward the first end 120 has been found to advantageously avoid overheating of the outer wall 114. The amount of heat diverted from the first end 120 will generally depend on other factors, such as the material and geometry of the vacuum insulation 110 and the operating temperature of the heater 108. A range of spacings can be tested for a particular embodiment to determine the necessary spacing of the thermal bridge 118 from the heater 108 to maintain the temperature of the outer surface of the vacuum insulation 110 adjacent the first end 120 at or below 48°C. This can be advantageous for both safety and efficiency. The longitudinal cross-sectional area or length of the thermal bridge 118 can also be varied to maintain this maximum temperature.

[0036] FIG. 4 is a schematic diagram of a portion of a vacuum insulation panel 110 in an alternative embodiment of the present invention. Dashed lines indicate the location of the outer wall 114, which has been removed from the view to allow the inner wall 112 and thermal bridge 218 to be seen. In the embodiment of FIG. 4, the thermal bridge 218 is provided as an annular ring that may also provide structural support to the inner wall 112 and outer wall 114. The thermal bridge 218 separates the vacuum 116 into a first portion 116a and a second portion 116b, thereby improving the insulation of the first end 120. The thermal bridge 218 may be configured to divert a greater amount of heat to the outer wall 114 compared to the thermal bridge 118 due to the larger cross-sectional area (taken in the longitudinal direction) of the thermal bridge 218.

[0037] In other embodiments, the thermal bridges 218 may have any other suitable shape and may or may not divide the vacuum 116 into different isolated portions. For example, the thermal bridges 118 may be provided as multiple annular arcs at spaced locations around the periphery of the inner wall 112.

Claims

1. 1. An aerosol generating device configured to generate an aerosol for inhalation by a user, comprising: a vacuum insulator having an inner wall and an outer wall with a vacuum sealed therebetween; a cavity capable of receiving an aerosol-forming substance, the cavity being disposed adjacent to the inner wall of the vacuum insulation material and having an opening that allows a user to insert the aerosol-forming substance into the cavity; a heater disposed in thermal contact with the inner wall and configured to heat an aerosol-forming material received in the cavity by thermal conduction to generate an aerosol; a thermal bridge between the inner wall and the outer wall, the thermal bridge enabling a path for heat conduction, the thermal bridge being disposed in the vacuum between the heater and a first end of the vacuum insulation closest to the opening, and enabling heat transfer from the inner wall to the outer wall by conduction; Equipped with the thermal bridge is disposed on the inner wall longitudinally between the heater and the first end of the vacuum insulation material; Aerosol generator.

2. 2. The aerosol generating device according to claim 1, wherein the thermal bridge is provided on the inner wall at a position spaced 1 mm or more from the heater toward the first end.

3. 3. The aerosol generating device of claim 2, wherein the position of the thermal bridge on the inner wall is selected to maintain the outer surface of the aerosol generating device adjacent the first end of the vacuum insulation at 48°C or less during use of the heater.

4. 4. The aerosol generating device according to claim 1, wherein the heater is provided on the inner wall in the vacuum.

5. 5. The aerosol generating device according to claim 1, wherein the thermal bridge comprises a metal such as stainless steel.

6. 6. An aerosol generating device according to claim 1, wherein the thermal bridge provides structural support to the inner and outer walls.

7. An aerosol generating device as described in any one of claims 1 to 6, wherein the thermal bridge comprises one or more ribs provided at circumferentially spaced positions on the inner wall.

8. 7. An aerosol generating device according to any one of claims 1 to 6, wherein the thermal bridge is configured to separate a first portion of the vacuum from a second portion of the vacuum.

9. 2. The aerosol generating device of claim 1, further comprising a plurality of heaters and a plurality of thermal bridges, each thermal bridge being longitudinally disposed between a respective heater and the first end of the vacuum insulation material.

10. 10. The aerosol generating device according to claim 1, wherein the vacuum insulation material has a closed second end opposite the first end.

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