WO2023144373A1 - An aerosol generating device with an insulating chamber - Google Patents

Abstract

An aerosol generating device (100) is disclosed comprising an insulating chamber, which may be a vacuum chamber (102), defined between an inner wall (104) and an outer wall (106). A heating chamber (108) is defined radially inwardly of the inner wall. The device also comprises a heater (110) on an outer surface of the inner wall. The heater is electrically connected to a first region (112) of the outer wall and to a second region (113) of the outer wall. The first and second regions are electrically insulated from each other by an insulator (118).

Description

AN AEROSOL GENERATING DEVICE WITH AN INSULATING CHAMBER

FIELD OF THE INVENTION

The present invention relates to an aerosol generating device. In particular, the invention relates to an aerosol generating device with a heater disposed within an insulating chamber, which may be a vacuum chamber.

BACKGROUND

It is a developing field of interest to produce electronic cigarettes that heat, but do not bum, a solid or semi-solid aerosol forming substrate which comprises tobacco. These devices typically receive a rod of tobacco in a heating chamber. The rod is heated to release aerosol which can be inhaled by a user. One issue in these devices is that the heater which supplies heat to the heating chamber can also undesirably heat the remainder of the device. In compact devices this can be disadvantageous because the temperature of the outer surfaces of the device, which are held by a user, can become unacceptably high. In order to mitigate these effects some aerosol generating devices have been provided with chambers that can space the heater from the outer surfaces. This can provide thermal separation between the heating chamber and the outer surfaces which are held by a user.

There is a demand for producing aerosol generating devices such as electronic cigarettes that include chambers with simplified construction. It is an object of the present invention to provide an aerosol generating device that addresses these requirements.

SUMMARY

According to an aspect of the present invention there is provided an aerosol generating device comprising: a chamber defined between an inner wall and an outer wall, wherein a heating chamber that can receive an aerosol forming substrate is defined radially inwardly of the inner wall; and a heater on an outer surface of the inner wall; wherein the heater is electrically connected to a first region of the outer wall and a second region of the outer wall, and wherein the first and second regions are electrically insulated from each other.

In this way, the construction of the aerosol generating device may be simplified and the size of the aerosol generating device may be reduced. This can be achieved because the outer wall of the chamber performs a dual function by enclosing the heater and providing electrical connections with the heater. In this way, there is no need to provide separate electrical terminals through the outer wall of the chamber. This approach can also improve the ease of assembly because the heater on the outer surface of the inner wall can be easily electrically connected to respective first and second regions on the outer wall.

Preferably, the chamber is a vacuum chamber. In this way, the outer wall, and thus the exterior of the device, may be better insulated from heat from the heater. As the skilled person would appreciate, a variety of materials could be provided within the chamber to provide heat insulation. These include, but are not limited to, powdered or fibrous materials such as aerogel, or air.

Preferably, the heater and the first region of the outer wall are biased towards one another. The heater and the second region of the outer wall can also be biased towards one another. This may be achieved by providing spring-loaded electrical connections. A biased electrical connector may be provided that is urged towards the outer wall and/or the heater, as appropriate.

In this way, the ease of assembly of the device is further increased because the electrical connections are established more easily in a confined space within the chamber. Furthermore, less stress is placed on components of the device such as the heater, which may be fragile, during the formation of the electrical connections between the first and second regions and in general use by a user. Additionally, the electrical connections can be more securely established, which can reduce the likelihood of connections becoming loose after a period of use or during rough handling.

Preferably, the outer wall comprises a side wall and a bottom wall. The outer wall may be substantially u-shaped or cup-shaped with a substantially cylindrical section having the side wall and a base section having the bottom wall. In this way, the device may be shaped such that it is convenient for use as an electronic cigarette. The inner wall may be nested within the outer wall and may have a similar shape.

In one configuration the first region of the outer wall may be on the side wall and the second region of the outer wall may be on the bottom wall. In an alternative set up, the first region of the outer wall may be on the side wall and the second region of the outer wall may be on the side wall. In yet a further embodiment the first region of the outer wall may be on the bottom wall and the second region of the outer wall may be on the bottom wall.

Preferably, the first and second regions are electrically insulated from each other by an insulator. In this way, the electrically live first and second regions may be prevented from being in electrical contact with each other and short-circuiting the device. The insulator may be a gasket or an electrical sealant, for example. The insulator may be arranged in the bottom wall or circumferentially within the side wall; the insulator may also be arranged in the side wall and the bottom wall. The insulator may define the boundary between the first region of the outer wall and the second region of the outer wall.

The device may be used for heating a plurality of aerosol forming substrates which can be removed and replaced once they are depleted. The aerosol forming substrate may comprise a tobacco substrate which may be solid or semi-solid that can be heated without burning. In alternative scenarios the aerosol forming substrate may comprise other kinds of substrate such as a vaporisable liquid substrate held in a reservoir. The inner wall may also be substantially cup-shaped. The heating chamber may be substantially cylindrical with a substantially circular cross-sectional shape. The aerosol forming substrate may be enclosed by a side wall of the heating chamber during heating and may abut a bottom wall of the heating chamber.

Preferably, the first region and the second region are electrically connected, respectively, to a power source. In this way, power may be provided to components of the device via a power source such as a battery. The battery may be a rechargeable battery or single-use battery.

Preferably, the heater is a resistive electrical heating element. In this way, the heater may be arranged in various configurations on the outer surface of the inner wall to provide appropriate heating properties to the aerosol forming substrate. The heating element may be configured to operate in a plurality of heating behaviours that a user may select.

Preferably, a non-linear path is provided along a surface of an insulator outside the chamber between the first region of the outer wall and the second region of the outer wall. In this way, the likelihood of a short-circuit being produced between the first region of the outer wall and the second region of the outer wall is reduced as the creepage distance between the first region of the outer wall and the second region of the outer wall may be increased, along the non-linear path. The nonlinear path may include straight sections and vertices. The non-linear path may also or alternatively include curved sections.

Preferably, the insulator projects from the outer wall, outside the chamber. This can increase the distance that electrons would need to travel along the surface of the insulator from the first region to the second region, thereby decreasing the risk of a short-circuit. This may be particularly useful when the insulator is very thin, and the separation of the first and second regions is very small. In some embodiments the insulator may project from the outer wall, inside the chamber; however, it is considered more important that the projection is outside the chamber, where air and other matter might otherwise support a flow of electrons that could cause a short circuit. The insulator may comprise a cross-section of any arbitrary profile that extends outwardly from the outer wall, outside of the chamber. The insulator may be configured to envelope a portion of either the first region or the second region of the outer wall. The insulator may be further configured to envelope a portion of the side wall or the bottom wall.

Preferably, the first region of the outer wall is clamped by the second region of the outer wall. More preferably, the second region of the outer wall comprises a groove in which the first region of the outer wall can be received to be clamped in place. In this way, a mechanical seal may be provided by the insulator between the first region of the outer wall and the second region of the outer wall. The insulator may provide the function of electrically insulating the first and second regions from each other alongside providing a mechanical seal in the outer wall to form the chamber.

Preferably, the first region of the outer wall is recessed from the second region of the outer wall. In this way, the length of the path along the surface of the insulator inside and outside the chamber between the first region and the second region may be increased. The distance that electrons would need to travel along the surface of the insulator from the first region to the second region is increased, thereby decreasing the risk of a short-circuit.

According to another aspect of the invention there is provided a method for manufacturing an aerosol generating device comprising: forming achamber between an inner wall and an outer wall, and forming a heating chamber that can receive an aerosol forming substrate defined radially inwardly of the inner wall; providing a heater on an outer surface of the inner wall; making an electrical connection between the heater and a first region of the outer wall and between the heater and a second region of the outer wall; and electrically insulating the first and second regions from one another. DESCRIPTION OF DRAWINGS

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

Figure 1 is a schematic cross-sectional view of a device in an embodiment of the invention;

Figure 2 is a schematic cross-sectional diagram of a device in an alternative embodiment of the invention;

Figure 3 is a schematic cross-sectional diagram of a device in an alternative embodiment of the invention;

Figures 4a, 4b and 4c are schematic cross-sectional diagrams of a device in an alternative embodiment of the invention;

Figure 5 is a schematic cross-sectional diagram of a device in an alternative embodiment of the invention;

Figure 6 is a schematic cross-sectional diagram of a device in an alternative embodiment of the invention; and

Figure 7 is a flowchart showing steps for manufacturing an aerosol generating device in an embodiment of the invention.

DETAILED DESCRIPTION

Figure 1 is a schematic cross-sectional diagram of an aerosol generating device 100 in an embodiment of the invention. The aerosol generating device 100 comprises a vacuum chamber 102 defined between an inner wall 104 and an outer wall 106. A heating chamber 108 is provided radially inwardly of the inner wall 104 for receiving an aerosol forming substrate (not shown). A heater 110 is provided on an outer surface of the inner wall 104. The heater 110 is a track heater that can be printed or coated on the outer surface of the inner wall 104. The heater 110 can heat the inner wall 104 and transfer heat into the heating chamber 108 by thermal conduction to heat an aerosol forming substrate that is received therein. The outer wall 106 is preferably contained within an outer shell (not shown) of the device which may be made of plastic, metal or any other suitable material.

The inner wall 104 is substantially cup-shaped or u-shaped. The inner wall 104 is nested within the outer wall 106 which has a similar shape. The inner and outer walls 104, 106 are joined together at their upper ends to enclose a vacuum between them.

The vacuum chamber 102 is configured to provide thermal insulation between the heat produced by the heater 110 and the outer wall 106. More specifically, the vacuum chamber 102 is configured to provide thermal insulation between the heat produced by the heater 110 and a user of the device. Generally, the device is held when a user grasps an outer shell (not shown) of the device which surrounds the outer wall 106. The vacuum chamber 102 is preferably an evacuated chamber. Alternatively, the vacuum chamber 102 may comprise a plurality of individual evacuated units arranged within the vacuum chamber providing the desired thermal insulation. The vacuum chamber 102 may be formed by welding, or otherwise connecting, the inner wall 104 and the outer wall 106 to each other at their upper ends using known techniques.

The vacuum chamber 102 is an insulating chamber that can provide thermal insulation between the heat produced by the heater 110 and the outer wall 106. Although the insulating chamber is described as a vacuum chamber in the present embodiment, other materials could alternatively be provided in the chamber in order to provide thermal insulation. Examples of alternative materials that could be used include powdered or fibrous materials such as aerogel, or air. The inner wall 104 is configured to define the inner surface of the vacuum chamber 102 and to define the heating chamber 108. In this embodiment the inner wall 104 is substantially cylindrical and has a circular cross-sectional shape to match the cross-sectional shape of an aersol forming substrate. The inner wall 104 also has a side wall and a bottom wall. The inner wall 104 is shaped so that an aerosol forming substrate can be snugly received in the heating chamber 108. The inner wall 104 is preferably made of a material that conducts heat efficiently such as metal.

The outer wall 106 is configured to define the exterior of the vacuum chamber 102. The outer wall 106 is also substantially cylindrical in shape and has a side wall 106a and a bottom wall 106b. The outer wall 106 is made of an electrically conductive material such as a metal.

The heating chamber 108 is configured to receive an aerosol forming substrate. The heating chamber 108 may comprise groove portions or other means suitable for retaining the aerosol forming substrate. A mouthpiece portion (not shown) can be provided from which the user may inhale an aerosol produced from the aerosol forming substrate. Alternatively, the aerosol forming substrate itself may be a mouthpiece through which aerosol can be inhaled.

The heater 110 is configured to heat an aerosol forming substrate received within the heating chamber 108. The aerosol forming substrate may comprise a tobacco substrate that may comprise shredded tobacco and which may be solid or semisolid that can be heated without burning. In alternative scenarios the aerosol forming substrate may comprise other kinds of substrate such as a vaporisable liquid substrate held in a reservoir.

A first electrical connector 114 and a second electrical connector 116 are configured to form electrical connections between the heater 110 and a first region 112 and a second region 113 of the outer wall respectively. In this example, the first 114 and second 116 electrical connectors are spring-loaded. In this way, the heater 110 and the respective regions of the outer wall 106 can be biased towards one another. In the example embodiment of Figure 1 the first electrical connector 114 is biased in a counter clockwise direction from the perspective of the connection with the heater 110; this tends to urge the electrical connector 114 into contact with the second region 113 of the outer wall 106. The second electrical connector 114 is also biased in a counter clockwise direction from the perspective of the connection with the heater 110 so that it is urged towards the first region 112 of the outer wall 106.

The first electrical connector 114 and the second electrical connector 116 facilitate the transmission of electrical power from the outer wall 106, which is configured to be connected to a power source, to the heater 110.

The insulator 118 is configured to electrically insulate the first 112 and second 113 regions of the outer wall from each other. The insulator 118 is provided in the outer wall 106. The insulator 118 comprises an insulating material, such as rubber or plastic. The insulator 118 may be a gasket or insulating strip provided in the outer wall 106. In the embodiments of Figures 1 and 3, the insulator 118 is provided in the bottom wall 106b of the outer wall 106. In the embodiment of Figure 2, the insulator 118 is provided circumferentially around the side wall 106a of the outer wall. In further alternative embodiments of the invention, the insulator 118 may be provided in the side wall 106a and the bottom wall 106b or a combination of the two.

In a preferred embodiment, the heater 110 also comprises electrical terminals 120. The first 114 and second 116 electrical connectors are configured to form electrical connections between the electrical terminals 120 of the heater 110 and a first region 112 and a second region 113 of the outer wall respectively.

In the embodiment of Figure 1 , the first electrical connector 114 forms an electrical connection between a first portion of the heater 110 and the first region 112 of the outer wall, the first region 112 being located on the side wall 106a of the outer wall. The second electrical connector 116 forms an electrical connection between a second portion of the heater 110 and the second region 113 of the outer wall, the second region 113 being located on the bottom wall 106b of the outer wall. The first 114 and second 116 electrical connectors are biased in a counter clockwise direction from the perspective of the connections with the heater 110. The insulator 118 is provided circumferentially in the bottom wall 106b.

In the alternative embodiment of Figure 2, the first electrical connector 114 forms an electrical connection between a first portion of the heater 110 and the first region of the outer wall 112, the first region 112 being located on the side wall 106a of the outer wall. The second electrical connector 116 forms an electrical connection between a second portion of the heater 110 and a second region of the outer wall, the second region 113 being located on the side wall 106a of the outer wall. The first 114 and second 116 electrical connectors are biased in a counter clockwise direction from the perspective of the connections with the heater 110. The insulator 118 is provided circumferentially in the side wall 106a.

In the embodiment of Figure 3, the first electrical connector 114 forms an electrical connection between a first portion of the heater 110 and the first region 112 of the outer wall, the first region 112 being located on the bottom wall 106b of the outer wall. The second electrical connector 116 forms an electrical connection between a second portion of the heater 110 and the second region 113 of the outer wall, the second region 113 being located on the bottom wall 106b of the outer wall. The second region 113 in this embodiment is a sub-area of the bottom wall 106b of the outer wall. The first electrical connector 114 is biased in a clockwise direction from the perspective of the connection with the heater 110. The second electrical connector 116 is biased in a clockwise direction from the perspective of the connection with the heater 110. The insulator 118 is provided in the sub-area of the bottom wall 106b.

The first and second regions 112, 113 can be respectively connected to a power source to induce a current flow between the first and second portions of the electrically resistive heater 110 thereby to generate heat.

In the embodiments of Figures 4a, 4b and 4c, the insulator 118 is provided in the bottom wall 106b of the outer wall 106. In this example, the insulator 118 is substantially ring shaped, provided circumferentially around the first region 112 of the outer wall, which is located on the bottom wall 106b. The insulator 118 comprises a protrusion 122 that is provided outwardly from the outer wall 106, outside of the vacuum chamber 102. The protrusion 122 is provided in an orientation that is substantially parallel to a longitudinal axis of the device, the longitudinal axis in this example defined as being parallel to the side wall 106a.

The protrusion 122 increases the shortest path 126, or creepage distance, that electrons would have to take along the surface of the insulator 118 from the first region 112 to the second region 113 of the outer wall (or vice-versa) in order to produce a short-circuit. It is believed that a short-circuit is more likely to be produced outside of the vacuum chamber 102 due to the presence or potential presence of matter on an external surface of the insulator 118 that may support a current flow, even if it is only a small current flow. The longer the shortest path 126 across the surface of the insulator 118 between the first and second regions, the lower the risk of a short-circuit.

The skilled person would understand that the protrusion 122 may have any arbitrary shape that may include a plurality of vertices and that the shortest path 126 taken across the surface of the insulator 118 may be an arc, for example. In the embodiment of Figure 4a, the protrusion 122 has a trapezoidal cross-section. The shortest path 126 is across two vertices of the protrusion 122 of the insulator 118. In the embodiment of Figure 4b, the protrusion 122 has a square crosssection. The shortest path 126 is across two vertices of the protrusion 122 of the insulator 118. In the embodiment of Figure 4c, the protrusion 122 has a triangular cross-section. The shortest path 126 is across the vertex of the protrusion 122 of the insulator 118.

In the embodiment of Figure 5, the insulator 118 is provided in the bottom wall 106b of the outer wall. In this example, the insulator 118 is substantially ring- shaped, provided circumferentially around the first region 112 of the outer wall, which is located on the bottom wall 106b. The insulator 118 comprises a protrusion 122 that is provided outwardly from the outer wall 106, substantially parallel to the longitudinal axis of the device, outside of the vacuum chamber 102. In this example, the first region 112 of the outer wall is recessed into the vacuum chamber 102, relative to the second region 113 of the outer wall, such that a greater portion of the protrusion 122 of the insulator 118 protrudes outwardly from the outer wall 106. The shortest path 126 across the insulator 118 is increased both inside and outside of the vacuum chamber 102 as the surface area of the insulator 118 is increased due to the recession of the first region 112 of the outer wall.

In the embodiment of Figure 6, the insulator 118 is substantially ring-shaped, provided circumferentially around the bottom wall 106b, between the side wall 106a and the bottom wall 106b. The insulator 118 comprises a recess on an interior surface that envelopes a portion of the bottom wall 106b, retaining the bottom wall 106b therein. The shortest path 126 is increased inside and outside of the vacuum chamber 102 as the surface area of the insulator 118 is increased due to the insulator 118 enveloping a portion of the bottom wall 106b.

In this example, the side wall 106a further comprises a groove or groove portions 124 that are configured to clamp and retain the bottom wall 106b in order to maintain a vacuum in the vacuum chamber 102. In this embodiment, the first region 112 is located on the side wall 106a and the second 113 region is located on the bottom wall 106b. It would be evident to a person skilled in the art that the arrangement illustrated in this embodiment of the invention may also be implemented in the side wall 106a.

Figure 7 is a flowchart showing stages for manufacturing an aerosol generating device 100 in an embodiment of the invention. At step 202, the heater 110 is provided on the inner wall 104. More specifically, the heater 110 is provided on the outer surface of the inner wall 104. In a preferred embodiment, the heater 110 is a track heater that can be printed onto the outer surface of the inner wall. In alternative embodiments, the heater 110 may be secured to the inner wall 104 by means such as an adhesive. Alternatively, the heater 110 may be wrapped around the inner wall 104.

At step 204, the heating chamber 108 is formed inwardly of the inner wall 104. At step 206, the first 112 and second 113 regions of the outer wall are insulated from each other using the insulator 118. In embodiments of the invention, the insulator 118 is a gasket comprising insulating material.

At step 208, a first electrical connection is made between the heater 110 and the first region 112 of the outer wall. At step 210, a second electrical connection is made between the heater 110 and the second region 113 of the outer wall.

The first and second electrical connections are made by a wire connecting the heater 110 to the first 112 and second 113 regions of the outer wall respectively. More specifically, the first and second electrical connections are made by spring- loaded electrical connectors.

At step 212, the vacuum chamber 102 is formed between the inner wall 104 and the outer wall 106. The vacuum chamber 102 is an evacuated chamber. Alternatively, the vacuum chamber 102 may comprise a plurality of individual evacuated units arranged within the vacuum chamber 102 providing the desired thermal insulation. The vacuum chamber 102 may be formed by welding, or otherwise connecting, the inner wall 104 and the outer wall 106 to each other using known techniques.

Claims

1. An aerosol generating device, comprising: a chamber defined between an inner wall and an outer wall, the outer wall made of an electrically conductive material, wherein a heating chamber that can receive an aerosol forming substrate is defined radially inwardly of the inner wall; and a heater on an outer surface of the inner wall; wherein the heater is electrically connected to a first region of the outer wall and a second region of the outer wall, and wherein the first and second regions are electrically insulated from each other.

2. An aerosol generating device according to claim 1 , wherein the chamber is a vacuum chamber.

3. An aerosol generating device according to any of the preceding claims, wherein the heater and the first region of the outer wall are biased towards one another.

4. An aerosol generating device according to any of the preceding claims, wherein the heater and the second region of the outer wall are biased towards one another.

5. An aerosol generating device according to any of the preceding claims, wherein the outer wall comprises a side wall and a bottom wall.

6. An aerosol generating device according to claim 5, wherein the first region of the outer wall is on the side wall and the second region of the outer wall is on the bottom wall.

7. An aerosol generating device according to claim 5, wherein the first region of the outer wall is on the side wall and the second region of the outer wall is on the side wall.

8. An aerosol generating device according to claim 5, wherein the first region of the outer wall is on the bottom wall and the second region of the outer wall is on the bottom wall.

9. An aerosol generating device according to any of the preceding claims, wherein the first region and the second region are electrically connected, respectively, to a power source.

10. An aerosol generating device according to any of the preceding claims, wherein a non-linear path is provided along a surface of an insulator outside the chamber between the first region of the outer wall and the second region of the outer wall.

11. An aerosol generating device according to claim 10, wherein the insulator projects from the outer wall, outside the chamber.

12. An aerosol generating device according to any of the preceding claims, wherein the first region of the outer wall is clamped by the second region of the outer wall.

13. An aerosol generating device according to claim 12, wherein the second region of the outer wall comprises a groove in which the first region of the outer wall can be received to be clamped.

14. An aerosol generating device according to any of the preceding claims, wherein the first region of the outer wall is recessed from the second region of the outer wall.

15. A method of manufacturing an aerosol generating device, comprising: forming a chamber between an innerwall and an outer wall, the outer wall being made of an electrically conductive material, and forming a heating chamber that can receive an aerosol forming substrate defined radially inwardly of the inner wall; providing a heater on an outer surface of the inner wall; making an electrical connection between the heater and a first region of the outer wall and between the heater and a second region of the outer wall; and electrically insulating the first and second regions from one another.