Aerosol generation device and heating chamber therefor

Abstract

A heating chamber (108) for an aerosol generation device (100) is provided. The heating chamber (108) comprises a first open end (110) through which a substrate carrier (132) containing an aerosol substrate (134) is insertable in a direction along a length of the heating chamber (108). The heating chamber (108) further comprises a sidewall (114) and a plurality of thermal engagement elements (120) for contacting the substrate carrier (132) and providing heat thereto. The heating chamber (108) further comprises a plurality of gripping elements (122) spaced apart from the thermal engagement elements (120) along the length of the sidewall (114), each gripping element (122) extending inwardly into the interior volume from an inner surface of the sidewall (114) at a different location around the sidewall (114), wherein the locations of the gripping elements (122) are closer to the first open end (110) than the thermal engagement elements (120).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an aerosol generating device and a heating chamber thereof. The present disclosure is particularly applicable to a portable aerosol generating device which can be self-contained and low temperature. Such a device can heat, rather than burn, tobacco or other suitable material by conduction, convection and / or radiation to generate an aerosol for inhalation. BACKGROUND

[0002] In the past few years, there has been a rapid growth in the popularity and use of devices (also known as vaporizers) that reduce or modify the risk, which have helped habitual smokers who want to quit smoking traditional tobacco products such as cigarettes, cigars, cigarillos and rolling tobacco. Various devices and systems are available that heat or warm a vaporizable substance, which is quite different from lighting tobacco in traditional tobacco products.

[0003] A commonly used, reduced or modified risk device is an aerosol generating device or a heat-not-burn device of a heated substrate. This type of device generates an aerosol or vapour by heating an aerosol substrate, which typically includes moist tobacco leaf or other suitable vaporizable material, to a temperature typically in the range of 100°C to 300°C. Heating, but not burning or combusting, the aerosol substrate releases an aerosol containing components sought by the user, but without or with fewer carcinogenic by-products produced by burning and combustion.

[0004] In the general sense, it is desirable to rapidly heat the aerosol substrate to a temperature at which an aerosol can be released therefrom without combustion, and to maintain the aerosol substrate at that temperature. Obviously, the aerosol released from the aerosol substrate in the heating chamber is delivered to the user when there is airflow through the aerosol substrate.

[0005] This type of aerosol generating device is a portable device, and therefore energy consumption is an important design consideration. The present invention aims to address the problems of existing devices and to provide an improved aerosol generating device and a heating chamber thereof. SUMMARY

[0006] According to a first aspect of the present disclosure, there is provided a heating chamber for an aerosol generation device, the heating chamber comprising: a first open end through which a substrate carrier containing an aerosol substrate can be inserted in a direction along a length of the heating chamber; a side wall defining an interior volume of the heating chamber; a plurality of thermal engagement elements for contacting the substrate carrier and providing heat thereto, each thermal engagement element extending inwardly from an inner surface of the side wall into the interior volume at a different location around the side wall; and a plurality of gripping elements spaced along the length of the side wall from the thermal engagement elements, each gripping element extending inwardly from the inner surface of the side wall into the interior volume at a different location around the side wall; wherein the gripping elements are located closer to the first open end than the thermal engagement elements.

[0007] It has been found that as the aerosol substrate is heated, the aerosol substrate shrinks away from the thermal engagement elements, and the compression force for maintaining the substrate carrier in the heating chamber and preventing it from falling out is no longer optimal. The plurality of gripping elements is therefore provided to mitigate this problem and provide additional grip on the substrate carrier.

[0008] Optionally, the thermal engagement elements and / or the gripping elements comprise a deformed portion of the side wall.

[0009] Optionally, the thermal engagement elements and / or the gripping elements comprise an embossed portion of the side wall.

[0010] Optionally, the side wall, the thermal engagement elements, and the gripping elements are formed as a single integral part.

[0011] Optionally, the side wall has a substantially constant thickness, the thickness being less than 1.2 mm, preferably 1.0 mm or less, most preferably between 0.9 (+ / - 0.01) and 0.7 (+ / - 0.01) mm.

[0012] Optionally, the side wall is formed from metal.

[0013] Optionally, the heating chamber has a central axis along which the substrate carrier can be inserted; and wherein each gripping element has an innermost portion for contacting the substrate carrier, wherein the innermost portions are all located at substantially the same radial distance from the central axis.

[0014] Optionally, the heating chamber has a central axis along which the substrate carrier can be inserted; wherein the gripping elements each have an innermost portion for gripping the substrate carrier located at a first radial distance from the central axis; and the thermal engagement elements each have an innermost portion for contacting the substrate carrier located at a second radial distance from the central axis; the first radial distance being greater than the second radial distance.

[0015] In other words, the gripping elements and the thermal engagement elements can define a first and a second limiting diameter of the heating chamber, respectively; the first limiting diameter being larger than the second limiting diameter. In particular, the first limiting diameter defined by the gripping elements is at least 0.05 mm larger, preferably between 0.1 and 0.5 mm larger, most preferably between 0.1 and 0.3 mm larger than the limiting diameter defined by the thermal engagement elements. For example, the first limiting diameter is 6.4 (+ / - 0.05) mm and the second limiting diameter is 6.2 (+ / - 0.05) mm. Such a difference in limiting diameter compensates for the difference in stiffness of the substrate carrier in the area where the elements engage the substrate carrier. In particular, the thermal engagement elements are preferably positioned in an area of the substrate carrier where an aerosol substrate, e.g. a tobacco-based substrate, is present. In this area, the substrate carrier has a very easy deformability due to the compressibility of the aerosol substrate. The gripping elements are positioned in a more rigid area of the substrate carrier, e.g. against a tube or filter of the substrate carrier. Due to the stiffness of the material in this zone, the substrate carrier is less deformable and therefore the size of the gripping elements is preferably designed to provide sufficient gripping without causing too much resistance or deformation to the substrate carrier.

[0016] In other words, optionally, the first radial distance is at least 0.05 mm larger, preferably between 0.1 and 0.5 mm larger, most preferably between 0.1 and 0.3 mm larger than the second radial distance.

[0017] Optionally, the thermal engagement elements have an overall elongated shape extending along the axial length of the heating chamber. The thermal engagement elements preferably have the same shape as each other. The elongated thermal engagement elements preferably form elongated ridges on the inner surface of the heating chamber and complementary grooves on the outer surface of the heating chamber corresponding to the elongated ridges. Optionally, the profile of the thermal engagement elements in a plane parallel to the length of the heating chamber is different from the profile of the gripping elements in a plane parallel to the length of the heating chamber.

[0018] Optionally, the profile of the thermal engagement elements in a plane parallel to the length of the heating chamber is based on a polygon having a plurality of straight edges, wherein adjacent straight edges meet at a corner. Optionally, one or more corners of the thermal engagement elements are rounded.

[0019] Optionally, the gripping elements have an overall shape that is the same as each other.

[0020] Optionally, the shape of the gripping elements is different from the shape of the thermal engagement elements.

[0021] Optionally, the number of thermal engagement elements is the same as the number of gripping elements.

[0022] Optionally, the thermal engagement elements extend along the length of the sidewall for a first distance, and the gripping elements extend along the length of the sidewall for a second distance, wherein the first distance is greater than the second distance.

[0023] Preferably, the length of the gripping elements is shorter than the length of the thermal engagement elements. The length is the axial extent along the length of the sidewall of the heating chamber.

[0024] Preferably, the gripping elements have a width substantially equal to their length. The width is the extent around the inner surface of the sidewall. For a circular sidewall, the width can be referred to as the circumferential width. The width is transverse to the length.

[0025] The thermal engagement elements are preferably elongate to enable an enlarged surface area for heat transfer, whereas the gripping elements only need to mechanically grip on the substrate carrier and can therefore be shorter than the thermal engagement elements. If the gripping elements are too long, some heat can be provided to a region of the substrate carrier via the gripping elements that is not heated, preferably due to proximity to the user's mouth.

[0026] Optionally, the length of the thermal engagement elements is at least 3 times the extent of the thermal engagement elements in the transverse direction around the sidewall. As used herein, the transverse direction is the width around the sidewall. Preferably, the length of the thermal engagement elements is between 20 and 30 times the extent (i.e. width) of the thermal engagement elements in the transverse direction around the sidewall. For example, the length of the thermal engagement elements is between 8 and 15 mm, such as 12.5 mm, and the width is between 0.3 and 1 mm, such as 0.5 mm.

[0027] Optionally, the length of the gripping elements is less than 2 times the extent of the gripping elements in the transverse direction around the sidewall. For example, the length of the gripping elements is substantially the same length as the extent (i.e. width) of the gripping elements in the transverse direction around the sidewall. For example, the length of the gripping elements is between 0.3 and 1 mm, such as 0.5 mm, and the width is between 0.3 and 1 mm, such as 0.5 mm. Such dimensions provide sufficient gripping of the substrate carrier, while avoiding too much resistance during insertion or removal, and reducing heat transfer from the heated sidewall to the upper region of the substrate carrier closer to the mouth end of the substrate carrier.

[0028] Optionally, the thermal engagement elements and / or the gripping elements have a convex profile in a plane parallel to the length of the heating chamber.

[0029] Optionally, at least one of the gripping elements has a pointed or rounded profile that extends inward into the interior volume, preferably wherein the pointed profile is triangular, or the rounded profile is a portion of a sphere.

[0030] Optionally, the gripping elements have a surface facing the first open end, which surface is inclined away from the first open end towards the central axis of the heating cavity.

[0031] The gripping elements can be formed as embossed indentations formed in the outer wall of the heating cavity. Such a design provides limited heat transfer but a firm gripping action. The gripping indentations can be curved innermost portions connecting the side wall at the circumference, which are substantially circular, elliptical, square or rectangular. The tips of the gripping elements (innermost inner portions) are preferably rounded or flat to avoid poking through the surface of the substrate carrier (e.g. tipping paper). For example, the indentations can form a partly elliptical, hemispherical, or trapezoidal profile at their innermost portions in a plane parallel to the length of the heating cavity. The indentations are formed in the outer surface of the heating cavity and can have a cavity comprising a substantially hemispherical innermost portion and an annular outermost portion connecting the tubular side wall. The annular outermost portion can be connected to the side wall by a slightly curved portion (e.g. having a radius of about 0.1 mm). For example, the diameter of the outermost portion can be between 0.3 and 1 mm, preferably between 0.4 and 0.7 mm, e.g. 0.6 mm, while the radius of the spherical innermost portion can be e.g. about 0.15 mm.

[0032] Optionally, the heat engagement elements have a flattened profile, preferably a trapezoidal profile, shaped for obtaining a distributed compression. In particular, the heat engagement elements have a surface adapted for achieving heat transfer to the substrate carrier by maximizing the contact surface area. For example, the contact surface can be complementary to the shape of the substrate carrier. The contact surface can be the surface of the heat engagement elements that extends farthest into the interior volume of the heating cavity.

[0033] Optionally, the heat engagement elements protrude into the interior volume of the heating cavity by a third distance relative to the side wall, and the gripping elements extend into the interior volume of the heating cavity by a fourth distance. Preferably, the third distance is greater than the fourth distance. In this way, the heat engagement elements protrude further into the interior volume of the heating cavity than the gripping elements.

[0034] Optionally, for obtaining a uniform heat distribution, the plurality of heat engagement elements are equally spaced from each other around the side wall. For achieving a uniform gripping force distribution to the substrate carrier and to center the substrate carrier axially aligned in the heating cavity, the plurality of gripping elements can also be equally spaced from each other around the side wall.

[0035] Optionally, the heating cavity further comprises a heat generator arranged for providing heat to the substrate carrier.

[0036] Optionally, the heat generator is a heater. Optionally, the heat generator is an electric heater. Preferably, the heat generator is an electric resistance heater, such as a thin film heater with metal heating tracks on a backing film.

[0037] Optionally, the heat generator is an electric heat generator comprising metal heating tracks on an electrically insulating backing layer.

[0038] Optionally, the heat generator is positioned on a portion of the outer surface of the sidewall.

[0039] Optionally, the heat generator is positioned to extend along the sidewall a fifth distance, such that at least a portion of the heat generator is positioned adjacent to at least a portion of the sidewall corresponding to the location of the thermal engagement elements.

[0040] Optionally, the heat generator is positioned such that the heat generator is not positioned adjacent to any portion of the sidewall corresponding to the location of the gripping elements.

[0041] Optionally, the heat generator extends along only a portion of the sidewall.

[0042] Optionally, the heat generator extends along a portion of the sidewall spaced apart from the first open end.

[0043] Optionally, the heat generator is spaced apart from the first open end by a sixth distance and spaced apart from a second end opposite the first open end by a seventh distance, wherein the sixth distance and the seventh distance are different.

[0044] Optionally, the heating cavity further comprises a metal layer between the heat generator and the sidewall.

[0045] Optionally, the metal layer extends further along the length of the heating cavity than the heat generator.

[0046] Optionally, the metal layer is an electroplated layer, preferably an electroplated copper layer.

[0047] Optionally, the heat generator comprises an electric heat generator with metal tracks and an electrically insulating backing layer.

[0048] Optionally, the heat generator is compressed against the sidewall under tension by a heat shrink layer.

[0049] Optionally, the heating cavity further comprises a flange at the first open end.

[0050] Optionally, the heating cavity further comprises a bottom at a second end of the sidewall opposite the first open end. The bottom can also be referred to as a base.

[0051] Optionally, the sidewall has a first thickness and the base has a second thickness, wherein the second thickness is greater than the first thickness.

[0052] Optionally, the base comprises a platform extending from an inner surface of the base, from a portion of the base towards the first open end.

[0053] Optionally, the platform is formed from a portion of the base.

[0054] Optionally, the platform comprises a deformed portion of the base.

[0055] Optionally, the sidewall is a tubular sidewall. Optionally, the sidewall is a cylindrical sidewall.

[0056] Optionally, the heating chamber further comprises the substrate carrier, the substrate carrier having a first portion and a second portion, wherein the first portion is positioned further from the first open end than the second portion when the substrate carrier is inserted into the heating chamber, and wherein the first portion comprises aerosol substrate.

[0057] Preferably, the thermal engagement elements are arranged to contact the first portion of the substrate carrier. Thus, heat can be concentrated towards the aerosol substrate contained in the first portion via contact with the thermal engagement elements. Due to the local engagement of the elements with the first portion of the carrier, an air gap is provided between adjacent thermal engagement elements and the substrate carrier to allow air to be drawn from the first open end of the heating chamber towards the second or base end.

[0058] Optionally, the gripping elements are arranged to grip the second portion of the substrate carrier.

[0059] The second portion of the substrate carrier preferably does not comprise aerosol substrate.

[0060] Optionally, the second portion of the substrate carrier is a hollow tube.

[0061] The second portion of the substrate carrier can be a filter and / or a cooling tube. The filter and / or cooling tube can be wrapped in paper and / or film (e.g. tipping paper, and / or a metallised or metal film).

[0062] Optionally, a longitudinal end of the thermal engagement elements closest to the first open end is aligned with a boundary between the first portion and the second portion of the substrate carrier when the substrate carrier is inserted into the heating chamber.

[0063] Optionally, the thermal engagement elements extend into the internal volume to contact the substrate carrier when the substrate carrier is inserted into the heating chamber.

[0064] Optionally, the gripping elements extend into the internal volume to grip the substrate carrier when the substrate carrier is inserted into the heating chamber.

[0065] According to a second aspect of the disclosure, there is provided an aerosol generating device comprising: a power supply; a heating chamber as disclosed herein; a heat generator arranged to provide heat to the heating chamber; control circuitry configured to control the supply of electrical power from the power supply to the heat generator; and an outer housing enclosing the power supply, the heating chamber, the heat generator, and the control circuitry, wherein the outer housing has an aperture formed therein for accessing an internal volume of the heating chamber.

[0066] Optionally, the aerosol generating device further comprises a thermal insulation member surrounding the heating chamber.

[0067] Optionally, the thermal insulation member is a vacuum thermal insulation member. For example, the vacuum thermal insulation member comprises a double-walled metal tube or cup having a vacuum contained between the walls.

[0068] Optionally, the thermal insulation member comprises a thermal insulating material. For example, the thermal insulating material comprises rubber (such as silicone, silicone foam, polyurethane foam, etc.), aerogel, or glass fibre insulation.

[0069] Embodiments of the disclosure will now be described, by way of example only, and with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 is a schematic perspective view of an aerosol generating device according to the disclosure, wherein shown is a substrate carrier containing aerosol substrate being loaded into the aerosol generating device.

[0071] Figure 2 is a schematic perspective view of an aerosol generating device according to the disclosure, wherein shown is a substrate carrier containing aerosol substrate being loaded into the aerosol generating device. Figure 1 is a schematic perspective view of an aerosol generating device according to the disclosure, wherein shown is a substrate carrier containing aerosol substrate being loaded into the aerosol generating device.

[0072] Figure 3 is a schematic perspective view of an aerosol generating device according to the disclosure, wherein shown is a substrate carrier containing aerosol substrate being loaded into the aerosol generating device. Figure 1 is a schematic perspective view of an aerosol generating device according to the disclosure, wherein shown is a substrate carrier containing aerosol substrate being loaded into the aerosol generating device.

[0073] Figure 4 is a schematic perspective view of an aerosol generating device according to the disclosure, wherein shown is a substrate carrier containing aerosol substrate being loaded into the aerosol generating device. Figure 1 is a schematic perspective view of an aerosol generating device according to the disclosure, wherein shown is a substrate carrier containing aerosol substrate being loaded into the aerosol generating device.

[0074] Figure 5A is a perspective cross-sectional view of a heating chamber according to the disclosure, and a thermal insulation member and upper and lower support members.

[0075] Figure 5Bis a schematic cross-sectional view of the heating chamber from the side according to the present disclosure.

[0076] Figure 6A is Figure 5B a schematic plan view of the heating chamber from above.

[0077] Figure 6B is Figure 5B a cross-sectional view within the plane B-B of the heating chamber.

[0078] Figure 6C is Figure 5B a cross-sectional view within the plane A-A of the heating chamber.

[0079] Figure 6D is Figure 6B a detail of the view of the portion P showing the gripping element of the heating chamber.

[0080] Figure 7 is Figure 5B a perspective view of the heating chamber.

[0081] Figure 8 is Figure 5B a schematic cross-sectional view of the heating chamber from the side, wherein it is shown that a substrate carrier containing an aerosol substrate has been loaded into the heating chamber.

[0082] Figure 9 is Figure 5B a perspective view of the heating chamber, wherein it is shown that a heat generator is attached to the outer surface of the heating chamber.

[0083] Figure 10 is a perspective view of an alternative heating chamber according to the present disclosure, wherein the gripping element is not aligned with the heat engagement element.

[0084] Figure 11 is Figure 10 a schematic plan view of the heating chamber from above.

[0085] Figure 12 is a schematic cross-sectional view through a gripping element in another alternative heating chamber according to the present disclosure, wherein the gripping element has a triangular lateral profile. DETAILED DESCRIPTION

[0086] Referring to Figures 1-4An aerosol generating device 100 is provided. The aerosol generating device 100 is arranged for receiving a substrate carrier 132 containing aerosol substrate 134, and is configured for heating the aerosol substrate 134 inserted therein to form an aerosol for inhalation by a user. The aerosol generating device 100 can be described as a personal inhaler device, an electronic cigarette (or e-cigarette), a vaporizer, or a vaping device. In the example shown, the aerosol generating device 100 is a heat-not-burn (HnB) device. However, as opposed to burning tobacco in conventional tobacco products, the aerosol generating device 100 contemplated in the present disclosure more often heats or stirs an aerosolisable substance to generate an aerosol for inhalation.

[0087] Referring to Figure 1 The aerosol generating device 100 comprises a housing 102 which houses a plurality of different components of the aerosol generating device 100. The housing 102 can be formed of any suitable material or even layers of materials. For example, a metallic inner layer can be surrounded by an outer layer of plastic or other material having a low thermal conductivity. This allows the housing 102 to be held comfortably by a user.

[0088] In the example shown, the elongated aerosol generating device 100 has a first end 104 and a second end 106 opposite the first end 104. For convenience, the first end 104 (shown as the bottom towards Figures 1-4 is described as the bottom, base or lower end of the aerosol generating device 100. For convenience, the second end 106 (shown as the top towards Figures 1-4 is described as the top or upper end of the aerosol generating device 100. In use, a user will typically orient the aerosol generating device 100 with the first end 104 facing downwards and / or in a distal position relative to the user’s mouth, and the second end 106 facing upwards and / or in a proximal position relative to the user’s mouth.

[0089] The housing 102 has an opening 124 for receiving the substrate carrier 132 therethrough to be heated in a heating chamber within the housing 102. In this example, the opening 124 is shown as facing towards the second end 106. The aerosol generating device 100 has a closure 125 for covering the opening 124. The closure 125 can be considered as a door for the opening 124. The closure 125 is configured for selectively covering and uncovering the opening 124, such that depending on the position of the closure 125, the opening 124 is substantially closed and open. In the closed configuration, this can prevent dust and moisture from entering the opening 124. Figure 1The closure 125 is shown in an open configuration, exposing the opening 124 for insertion of a substrate carrier 132. The closure 125 can also function as a user operable button. The closure 125 is depressible in the open configuration to activate the aerosol generating device 100 to heat the aerosol substrate 134 within the heating chamber 108 to generate an aerosol.

[0090] Referring to Figure 2 The aerosol generating device 100 comprises a heating chamber 108 positioned towards the second end 106 of the aerosol generating device 100. The heating chamber 108 is arranged towards an opening 124 in the aerosol generating device 100, proximal to the second end 106. In other examples, the heating chamber 108 is positioned elsewhere within the aerosol generating device 100. The heating chamber 108 is arranged within the aerosol generating device 100 such that it is enclosed by the housing 102.

[0091] The heating chamber 108 is generally cup-shaped in form. The heating chamber 108 extends along a central axis E, such that the axial length of the heating chamber 108 is substantially aligned with the central axis E. The heating chamber 108 comprises a first open end 110 arranged towards the second end 106 of the aerosol generating device 100. In Figure 1 The first open end 110 is aligned with the opening 124 at the second end 106 of the aerosol generating device 100 in this example. The heating chamber 108 is closed at the end opposite the first open end 110. In other words, the heating chamber 108 comprises a base 112 opposite the first open end 110. The base 112 can also be referred to as the bottom of the heating chamber 108.

[0092] The heating chamber 108 further comprises a sidewall 114. The sidewall 114 is arranged as a thin-walled, preferably having a thickness of 80-100 pm. In this example, the sidewall 114 is tubular and has a generally circular cross-section. In this regard, the sidewall 114 can be generally referred to as a tubular wall of the heating chamber 108. Thus, the heating chamber 108 is generally cylindrical. However, other shapes are envisaged and the heating chamber 108 can have a wide tubular shape with, for example, an elliptical or polygonal cross-section. In other examples, the sidewall 114 tapers along its length, such that the cross-sectional area defined by the sidewall 114 perpendicular to its length is different at the first open end 110 than at the base 112. The heating chamber 108 has a generally tubular shape substantially aligned with the axial length of the aerosol generating device 100.

[0093] In this example, the central axis E is aligned with the centroid of the circular cross-section of the sidewall 114 and is the geometric centre axis of the cylindrical sidewall 114. The length of the sidewall 114 is parallel to the central axis E. The length of the sidewall 114 is defined as the dimension between the base 112 and the first open end 110.

[0094] As used herein, "diameter" refers to width, and in cases where the sidewall 114 does not have a circular cross-section, it is understood that "diameter" refers to the width of the cross-section, in particular the smallest width of the cross-section passing through the centroid of the cross-section (i.e. passing through the central axis E). For example, in cases where the sidewall 114 has a square cross-section, the width of the sidewall 114 is the distance between two opposite faces of the square (measured perpendicular to the two opposite faces).

[0095] As used herein, "circumference" refers to the perimeter, and in cases where the sidewall 114 does not have a circular cross-section, it is understood that "circumference" refers to the outer perimeter of the cross-section.

[0096] The base 112 forms an end face of the cylindrical heating chamber 108. The heating chamber 108 has an internal volume defined by the sidewall 114 and the base 112. The sidewall 114 connects the base 112 with the first open end 110 to form the cup shape of the heating chamber 108. In other examples, the heating chamber 108 has one or more holes, or is otherwise perforated at the base 112. In yet further examples, the heating chamber 108 can not have a base 112, but be an open-ended tube. In this case, the length of the heating chamber 108 is the shortest distance along the sidewall 114 between the open ends.

[0097] The heating chamber 108 further comprises a flange 116 at the first open end 110, and a platform 118 in the base 112. The sidewall 114 comprises a plurality of thermal engagement elements 120 and a separate plurality of grip elements 122. The heating chamber 108 is described in more detail below with reference to Figures 5 to Figure 9

[0098] The heating chamber 108 is arranged to receive a substrate carrier 132 containing aerosol substrate 134. For example, the aerosol substrate 134 can contain a mixture of tobacco and a humectant. The heating chamber 108 is configured to heat the aerosol substrate 134 within the substrate carrier 132 to generate an aerosol for inhalation, as described below.

[0099] Referring to Figure 2 ​The aerosol generating device 100 comprises a power source 126. Thus, the aerosol generating device 100 is electrically powered. That is, the aerosol generating device is arranged for using electrical power to heat the aerosol substrate 134. In this example, the power source 126 is a battery. The power source 126 is coupled to control circuitry 128. The control circuitry 128 in turn is coupled to the heat generator. For example, the heat generator can be an electrical heat generator. More specifically, the heat generator can be an electrical resistance heat generator having a heating element in the form of a metal track on the backing film. For example, the heat generator can be a thin film heater such as an electrically resistive heating track encased in an electrically insulating film such as polyimide. When an electric current is passed through the heating element, the heating element heats up and the temperature increases. In another example, the heat generator can be an inductive heater. In this case, the heat generator can refer to the inductive heating source, the susceptor or both.

[0100] The user operable button of the closure 125 is arranged for coupling and decoupling the power source 126 from the heat generator via the control circuitry 128. In other examples, the heating chamber 108 is heated in other ways, for example by burning a combustible gas.

[0101] The heat generator is attached to the outer surface of the heating chamber 108 and is in thermal contact with the outer surface of the side wall 114 to allow good heat transfer from the heat generator to the heating chamber 108. The heat generator extends around the heating chamber 108. In particular, the heat generator is in contact with the outer surface of the side wall 114. In more detail, the heat generator extends around the side wall 114 but not around the base 112.

[0102] As described in more detail below, the heating chamber 108 comprises a plurality of thermal engagement elements 120, shown as Figure 2 recesses in the side wall 114. As used herein, when the heat generator is described as contacting around the entire side wall 114, it is understood that this means that the heat generator extends around the entire circumference of the side wall 114, but it can not be in full contact with the side wall 114 at all points, especially inside the recesses of the thermal engagement elements 120.

[0103] In Figure 1In this example, the heat generator extends over a portion of the length of the side wall 114. The heat generator can not extend over the entire length of the side wall 114, but the heat generator preferably extends all the way around the side wall 114. In this context, length is from the base 112 to the first open end 110. The heat generator can not necessarily extend to one or more ends of the side wall 114. In particular, the heat generator can not extend to this end of the side wall 114 adjacent to the first open end 110, and / or the heat generator does not extend to this end of the side wall 114 adjacent to the base 112. In this example, the heat generator is generally centrally mounted along the height of the side wall 114. That is, the heat generator does not extend to either end of the side wall 114. In other words, the heat generator is spaced apart from this end of the side wall 114 adjacent to the first open end 110, and spaced apart from this end of the side wall 114 adjacent to the base 112.

[0104] When the substrate carrier 132 is inserted into the heating cavity 108, the heat generator is arranged to substantially overlap the region of the aerosol substrate 134. Preferably, the aerosol substrate 134 is fully inserted into the heating cavity 108, such that the top of the heating cavity 108 towards the first open end 110 is arranged to overlap the portion of the substrate carrier 132 that does not contain the aerosol substrate 134 when inserted. In other words, the portion of the substrate carrier 132 that does not contain the aerosol substrate 134 is aligned with the first open end 110. It is preferable to limit heating of these components by concentrating heat on the aerosol substrate 134 to improve heating efficiency. By not having the heat generator overlap the portion of the sidewall 114 towards the first open end 110, such that heat generated by the heat generator is concentrated. The sidewall 114 is preferably very thin (typically less than 100 pm) to achieve this by limiting heat transfer along the thin sidewall 114. This can reduce heat transfer to the portions not covered by the heat generator. Additionally, by inhibiting heating towards the base 112, this prevents scorching of the tip of the substrate carrier 132. In this way, a further distinction is made between the effects provided by the heat engagement element 120 and the grip element 122. More specifically, the heat engagement element 120 is arranged to receive heat generated by the heat generator and transfer heat into the aerosol substrate 134. Thus, the heating cavity 108 as a whole is arranged to inhibit heat flow to the grip element 122, and / or thereafter to the aerosol substrate 134 in the region of the grip element 122, by the combined effect of the positioning of the heat generator, the shape of the grip element 122 (e.g. arranged to have a small contact area with the substrate carrier 132), and the thin design of the sidewall 114 (preventing heat transfer along the heating cavity 108). In some examples, additional features such as a layer of metal (e.g. copper) can be provided to mark the areas that are to be heated (e.g. the heat engagement element 120, which can be coated with copper) from the areas that are not intended to be heated (e.g. the grip element 122, which should not be coated). In this way, the various features of the heating cavity 108 described herein act individually or in combination to provide the different functions of the heat engagement element 120 and the grip element 122.

[0105] In alternative examples, the heat generator can extend the entire length of the sidewall 114.

[0106] To improve the thermal insulation of the heating cavity 108, the heating cavity 108 is surrounded by an insulator. In this example, the insulating member 146 is an insulating tube. The insulating member 146 can be double-walled, having an inner wall and an outer wall separated by an internal space. The top and bottom of the tube of the insulating member 146 are sealed to connect the inner wall and the outer wall, such that the internal space is enclosed within the insulating member 146. The insulating member 146 comprises a vacuum within the internal space to further improve thermal insulation, and in other embodiments can comprise an insulating material such as a hydrogel or foam.

[0107] In this example, the heating chamber 108 is secured to the aerosol generation device 100 by a flange 116. The heating chamber 108 is mounted to the aerosol generation device 100 by at least one support member 150, 152. In Figure 2 In this example, the aerosol generation device 100 comprises an upper support member 150 and a lower support member 152. Referring to Figure 5A The mounted heating chamber 108 is shown in more detail. The upper support member 150 is configured to be secured to the flange 116 of the heating chamber 108. In alternative examples, for example in examples where the flange 116 is not provided, the upper support member 150 encircles the outer surface of the side wall 114 facing the first open end 110. The upper support member 150 is engaged between the heating chamber 108 and the thermal insulation member 146. The lower support member 152 is configured to be secured to the base 112 of the heating chamber 108. The heating chamber 108 is thus held at each end and fixed in place relative to the thermal insulation member 146. Preferably, the support members 150, 152 are made of a thermally insulating material to improve the thermal insulation between the heating chamber 108 and the thermal insulation member 146. The assembly of the heating chamber 108 and the thermal insulation member 146 coupled by the support members 150, 152 is then mounted in the aerosol generation device 100, for example by attachment to a frame enclosed within the outer housing 102.

[0108] This arrangement means that the thermal conduction from the heating chamber 108 of the aerosol generation device 100 to the outer housing 102 is limited by the thermal insulating properties of the support members 150, 152. Providing the heating chamber 108 attached only by the support members 150, 152 provides a well-insulated thermal conduction path for the heat to travel, instead of for example allowing the heat to escape directly from the side wall 114 in contact with the outer housing 102. This helps to keep the outer housing 102 at a temperature that is comfortable for the user and improves heating efficiency.

[0109] In some examples, the heat generator is held to the heating chamber 108 from the outside of the heat generator. That is, the heat generator is held to the heating chamber 108 from the outside of the heat generator, rather than from between the heat generator and the heating chamber 108. For example, this avoids the use of adhesive between the heat generator and the outer surface of the side wall 114 of the heating chamber 108. Removing a layer between the heat generator and the heating chamber 108 can improve heat transfer and improve heating efficiency.

[0110] In some examples, the heat generator can be surrounded by a heat shrink material that exerts pressure on the outer surface of the heat generator and onto the heating chamber 108. This compresses the heat generator onto the outer surface of the heating chamber 108 and promotes thermal contact. The heat shrink material can be wrapped around the heat generator and heated to provide the compression force.

[0111] The heating chamber 108 of the aerosol generating device 100 is arranged to receive a substrate carrier 132. Typically, the substrate carrier 132 contains an aerosol substrate 134, such as tobacco or another suitable aerosolisable material capable of being heated to generate an aerosol for inhalation. In this example, the heating chamber 108 is dimensioned to receive a single serving of aerosol substrate 134 in the form of a substrate carrier 132 (also referred to as a “consumable”), for example Figures 1-4 However, this is not essential and in other examples the heating chamber 108 is arranged to receive other forms of aerosol substrate 134, such as loose tobacco or tobacco otherwise packaged.

[0112] The substrate carrier 132 is of a generally tubular and elongate shape. In this example, the substrate carrier 132 is cylindrical and mimics the shape of a cigarette. In this example, the substrate carrier 132 has a length of 55mm. The substrate carrier 132 has a diameter of 7mm. The substrate carrier 132 comprises an aerosol substrate 134, and an aerosol collection region 136 adjacent to the region of aerosol substrate 134. The aerosol collection region 136 can be a paper or cardboard tube which is less compressible than the aerosol substrate 134. The substrate carrier 132 has a first end 138 and a second end 140 opposite the first end 138. The first end 138 and the second end 140 define the two ends of the elongate cylindrical shape of the substrate carrier 132. The aerosol substrate 134 is arranged towards the first end 138. The first end 138 is configured to be inserted into the heating chamber 108. The second end 140 is configured as a mouthpiece for a user to insert their mouth into in order to inhale the aerosol generated by heating the aerosol substrate 134.

[0113] In general, the aerosol substrate 134 is arranged at the first end 138 and extends partially along the length between the first end 138 and the second end 140 of the substrate carrier 132. In this example, the aerosol substrate 134 has a length of 20mm. The aerosol collection region 136 abuts the aerosol substrate 134 and is arranged between the aerosol substrate 134 and the second end 140. In this example, the aerosol collection region 136 does not extend all the way to the second end 140.

[0114] If a filter is provided, it is typically provided towards the second end 140. The length of the aerosol collection region 136 is about 20mm. The length of the aerosol substrate is also about 20mm. The substrate carrier 132 further comprises an outer layer 142 which wraps the components of the substrate carrier 132. For example, the outer layer 142 is paper (e.g. having a basis weight of about 40-100gsm).

[0115] Referring to Figure 1 and Figure 2Figure 1 shows the substrate carrier 132 before being loaded into the aerosol generating device 100. When a user wants to use the aerosol generating device 100, the user first loads the substrate carrier 132 for the aerosol generating device 100. This involves inserting the substrate carrier 132 into the heating cavity 108. The substrate carrier 132 is oriented such that the first end 138 of the substrate carrier 132 enters the heating cavity 108 when inserted into the heating cavity 108. Thus, the substrate carrier 132 is inserted into the heating cavity 108 with the first end 138 facing towards the base 112. The substrate carrier 132 is inserted until the first end 138 of the substrate carrier 132 abuts the base 112, in particular the platform 118 which is higher than the base 112, as shown in Figure 4

[0116] As can be seen from Figure 3 and Figure 4 , only a portion of the length of the substrate carrier 132 is within the heating cavity 108 when the substrate carrier 132 has been inserted as far as it can go into the heating cavity 108. In particular, the entire aerosol substrate 134 and most of the aerosol collection region 136 are positioned within the heating cavity 108. The remainder of the length of the substrate carrier 132 protrudes from the heating cavity 108 and beyond the second end 106 of the aerosol generating device 100. This provides a position for the user to place their mouth on the substrate carrier 132 to inhale aerosol.

[0117] The heat generator causes heat to be conducted through the heating cavity 108 to heat the aerosol substrate 134 of the substrate carrier 132. At least a portion of the side wall 114 of the heating cavity 108 is arranged to be in contact with the substrate carrier 132 to enable heat to be conducted from the heating cavity 108 to the substrate carrier 132, as described in more detail below with reference to Figures 5 to Figure 9 In particular, heat is conducted through the thermal engagement element 120. Conventionally, heat is also transferred by heating the surrounding air which is then drawn into the substrate carrier 132.

[0118] The heat generator heats the aerosol substrate 134 to a temperature at which vapour can begin to be released. Once heated to a temperature at which vapour can begin to be released, the user draws vapour along the length of the substrate carrier 132 to be inhaled at the user’s mouth. Figure 4 The direction of flow of the aerosol through the substrate carrier 132 is indicated by arrow A in Figure 1.

[0119] It will be appreciated that, as the user draws along Figure 4 ​When the direction of arrow A sucks in air and / or vapour, air or a mixture of air and vapour flows from the vicinity of the aerosol substrate 134 in the heating chamber 108 through the substrate carrier 132. This action also sucks ambient air from the environment surrounding the aerosol generating device 100 and from between the substrate carrier 132 and the side wall 114 into the heating chamber 108 (via the flow path indicated by arrow B in Figure 4 When the direction of arrow A sucks in air and / or vapour, air or a mixture of air and vapour flows from the vicinity of the aerosol substrate 134 in the heating chamber 108 through the substrate carrier 132. This action also sucks ambient air from the environment surrounding the aerosol generating device 100 and from between the substrate carrier 132 and the side wall 114 into the heating chamber 108 (via the flow path indicated by arrow B in Figure 4 The heated air heats the aerosol substrate 134 to generate an aerosol. More specifically, in this example, air enters the heating chamber 108 through a space provided between the side wall 114 of the heating chamber 108 and the outer layer 142 of the substrate carrier 132. To this end, the outer diameter of the substrate carrier 132 is smaller than the inner diameter of the heating chamber 108. More specifically, in this example, the inner diameter of the heating chamber 108 is 10 mm or less, preferably 8 mm or less, and most preferably approximately 7.6 mm. This allows the substrate carrier 132 to have a diameter of approximately 7.0 mm (± 0.1 mm). This corresponds to an outer circumference of the substrate carrier 132 of 21 mm to 22 mm. In other words, the space between the substrate carrier 132 and the side wall 114 of the heating chamber 108 is most preferably approximately 0.3 mm. In other variants, this space is at least 0.2 mm, and in some examples up to 0.4 mm.

[0120] The operation of the heating chamber 108 to heat the aerosol substrate 134 to generate an aerosol will now be described in more detail with reference to Figures 5 to Figure 9

[0121] Referring to Figures 5 to Figure 9 , a heating chamber 108 for use with the aerosol generating device 100 of the present disclosure is shown in detail. For example, the heating chamber 108 of Figures 5 to Figure 9 may be provided in the aerosol generating device 100 described above with respect to Figures 1-4 As mentioned above, the heating chamber 108 is generally provided for transferring heat from a heat generator arranged on an outer surface of the heating chamber 108 to a substrate carrier 132 received in the heating chamber 108 to generate an aerosol for inhalation.

[0122] The heating chamber 108 comprises a flange 116 at the first open end 110. The flange 116 extends outwardly away from the side wall 114 of the heating chamber 108 by a distance of approximately 1 mm, forming an annular structure. In this example, the flange 116 extends perpendicularly to the height of the side wall 114, such that the flange 116 extends horizontally when the heating chamber 108 is arranged vertically. In alternative examples, the flange 116 can extend at an angle, for example providing a bevelled, flared or inclined flange 116. In some examples, the flange 116 is positioned around only a portion of the rim of the side wall 114, rather than being annular.

[0123] The base 112 of the heating chamber 108 comprises a platform 118 that is raised relative to the remainder of the base 112 towards the first open end 110. The platform 118 does not extend across the entire base 112. The platform 118 is arranged towards the centre of the base 112 and provides a space between the platform 118 and the side wall 114 around the platform 118. The platform 118 is configured to space the substrate carrier 132 from a portion of the base 112 when the substrate carrier 132 is received in the heating chamber 108. This reduces the contact area of the heating chamber 108 with the first end 138 of the substrate carrier 132, preventing scorching. Additionally, by exposing a portion of the first end 138 of the substrate carrier 132, this facilitates airflow into the first end 138 of the substrate carrier 132.

[0124] In this example, the platform 118 is substantially circular, providing an annular space towards the base 112 between the platform 118 and the side wall 114. This allows for uniform airflow into the substrate carrier 132, which can provide uniform heating of the aerosol substrate 134, providing a more efficient heating and a more enjoyable experience for the user. Furthermore, the space between the platform 118 and the side wall 114 provides an area in which any aerosol substrate 134 that drops from the first end 138 of the substrate carrier 132 can collect. In this example, the platform 118 is circular and has a diameter of approximately 4 mm. In this example, the platform 118 is approximately 1 mm higher than the remainder of the base 112.

[0125] The side wall 114 is arranged to be thin walled. Typically, the side wall 114 is less than 100 pm thick, for example approximately 90 pm, or even approximately 80 pm thick. In some cases, the side wall 114 can be approximately 50 pm thick. Generally, the range of 50 pm to 100 pm is typically optimal. Manufacturing tolerances are approximately ±10 pm.

[0126] By having the side wall 114 of such a thickness, the thermal characteristics of the heating chamber 108 are significantly altered. Heat transport through the thickness of the side wall 114 is negligible as the side wall 114 is so thin, resulting in improved thermal conduction from the heat generator to the substrate carrier 132 to be heated. However, heat transport along the side wall 114 (i.e. along the length of the side wall 114 parallel to the central axis E or around the circumference of the side wall 114) has a thin channel along which conduction can occur and so heat generated by the heat generator located on the outer surface of the heating chamber 108 remains concentrated near the heat generator in a direction radially outward from the side wall 114 at the first open end 110 but quickly results in the inner surface of the heating chamber 108 heating up. Additionally, the thin side wall 114 helps to reduce the thermal mass of the heating chamber 108, in turn improving the overall efficiency of the aerosol generating device 100 as less energy is used to heat the side wall 114.

[0127] In some examples, the heating chamber 108 is formed of a material that allows heat concentration as described above. For example, the heating chamber 108, in particular the side wall 114 of the heating chamber 108, comprises a material having a thermal conductivity of 50 W / mK or less. In this example, the heating chamber 108 is a metal, preferably stainless steel. The thermal conductivity of stainless steel is between approximately 15 W / mK and 40 W / mK, the exact value depending on the specific alloy. As another example, the thermal conductivity of 300 series stainless steel suitable for this purpose is approximately 16 W / mK. Suitable examples include 304, 316 and 321 stainless steel, such stainless steels having been approved for medical use, being strong, and having a thermal conductivity low enough to allow the heat concentration described herein.

[0128] In this example, a deep draw process is used to provide a cup-shaped heating chamber 108 with a depth greater than a width. This is a very effective method of forming a heating chamber 108 with very thin side walls 114. The deep draw process involves pressing a sheet of metal with a punch tool to force it into a shaped die mouth. By using a series of progressively smaller punch tools and die mouths, a tubular structure is formed which has a base 112 at one end and provides a tube which is deeper than it is across the tube (this refers to the length of the tube being relatively greater than its width, which gives rise to the term "deep draw"). Since it is formed in this way, the side walls 114 of the tube formed in this way are the same thickness as the original sheet of metal. Similarly, the base 112 formed in this way is the same thickness as the initial sheet of metal blank. The flange 116, thermal engagement elements 120, and gripping elements 122 can be formed by hydroforming. This operation can include a preliminary annealing step to reduce the hardness of the metal and to facilitate deformation. This hydroforming operation can operate by injecting water at high pressure into the tubular cup to form the side walls 114 against an outer die. The flange 116 can be formed in an annular recess of the die, which is then cut to its final shape. The thermal engagement elements 120 and gripping elements 122 can be formed by providing complementary protrusions disposed on the surface of the outer die. This die can be formed from several parts to allow it to open after the forming stage so that the heating chamber 108 can be removed from the die.

[0129] Further structural support can be provided by the flange 116 at the first open end 110 of the heating chamber 108. The flange 116 resists bending and shear forces on the side walls 114. In this example, the flange 116 is the same thickness as the side walls 114, but in other examples the flange 116 is thicker than the side walls 114 to improve resistance to deformation. Any thickness added to a particular part for strength is weighed against the increased thermal mass introduced to keep the aerosol generating device 100 robust and efficient overall.

[0130] In particular, in this example the heating chamber 108 has a length of approximately 31 mm. That is, the side walls 114 have a length of approximately 31 mm. The heating chamber 108 has an internal diameter of approximately 7.6 mm, which is sized to receive a substrate carrier 132 of approximately 7 mm diameter. The side walls 114 are 80 pm thick, but the base is 0.4 mm thick to provide additional support.

[0131] Suitable alternative dimensions are readily envisaged to provide the functionality described herein for receiving a substrate carrier.

[0132] The heating chamber 108 includes a plurality of thermal engagement elements 120. The thermal engagement elements 120 are protrusions formed on the inner surface of the sidewall 114. In fact, the terms "thermal engagement element" and "protrusion" are used interchangeably herein. The width of the thermal engagement elements 120 around the circumference of the sidewall 114 is small relative to their length parallel to the length of the sidewall 114. In this example, there are four thermal engagement elements 120.

[0133] In this example, the thermal engagement elements 120 are formed as indentations in the sidewall 114. The gripping elements 122 can be formed as indentations in the same manner. These are formed by deforming the sidewall 114 towards one side to form an indentation on the inner surface of the sidewall 114 and a recess on the outer surface of the sidewall 114. Thus, the term "indentation" is also used interchangeably with the term "protrusion". Forming the thermal engagement elements 120 by making indentations in the sidewall 114 has the advantage that the indentations are integral with the sidewall 114 and therefore have minimal impact on heat flow. Additionally, the indentation-style thermal engagement elements 120 and gripping elements 122 do not add any thermal mass, which would be added if additional elements were added to the inner surface of the sidewall 114 of the heating chamber 108. Finally, making indentations in the sidewall 114 as described increases the strength of the sidewall 114 by introducing sections that extend transversely to the sidewall 114, thus providing resistance to bending of the sidewall 114.

[0134] The thermal engagement elements 120 are arranged to facilitate the transfer of heat from the heat generator into the aerosol substrate 134. The aerosol generation device 100 operates by conducting heat from the surfaces of the thermal engagement elements 120 that engage the outer layer 142 of the substrate carrier 132. In this way, the thermal engagement elements 120 on the inner surface of the sidewall 114 engage the substrate carrier 132 when it is inserted into the heating chamber 108. This causes the aerosol substrate 134 to be heated by conduction. Thus, as used herein, the thermal engagement elements 120 can be referred to as "heat transfer elements" or "conduction elements".

[0135] The aerosol generating device 100 also works by heating the air in the air gap between the inner surface of the side wall 114 and the outer layer 142 of the substrate carrier 132. That is, as the user sucks on the aerosol generating device 100, there is convective heating of the aerosol substrate 134 as the heated air is drawn through the aerosol substrate 134. The increased width and height (i.e. the distance each thermal engagement element 120 extends along the heating chamber 108) increases the surface area of the side wall 114 that transfers heat to the air, thus allowing the aerosol generating device 100 to reach an effective temperature more quickly. Furthermore, as the thermal engagement elements 120 extend into the internal volume to contact the substrate carrier 132, a plurality of air flow paths are defined between adjacent thermal engagement elements 120. As air enters the heating chamber 108 at the first open end 110, it passes between the side wall 114 and the substrate carrier 132 and is forced through between adjacent thermal engagement elements 120. The number and size of the thermal engagement elements 120 must be chosen to ensure that an adequate supply of air is provided to ensure sufficient and even heating and draw resistance. It has been found that four thermal engagement elements 120 are suitable to provide sufficient even heating of the aerosol substrate 134 and to provide an air flow passage of suitable size.

[0136] It will be apparent that, in order to conduct heat into the aerosol substrate 134, the surface of the thermal engagement element 120 must be in mutual engagement with the outer layer 142 of the substrate carrier 132. However, manufacturing tolerances can result in minor variations in the diameter of the substrate carrier 132. Additionally, due to the relatively soft and compressible nature of the outer layer 142 of the substrate carrier 132 and the aerosol substrate 134 held therein, any damage or rough handling of the substrate carrier 132 can result in the diameter being reduced or the shape being altered to an oval or elliptical cross-section in the region of the outer layer 142 intended to be in mutual engagement with the surface of the thermal engagement element 120. Accordingly, any variation in the diameter of the substrate carrier 132 can result in a reduction in the thermal engagement between the outer layer 142 of the substrate carrier 132 and the surface of the thermal engagement element 120, which adversely affects the conduction of heat from the thermal engagement element 120 through the outer layer 142 of the substrate carrier 132 into the aerosol substrate 134. In order to mitigate the effects of any variation in the diameter of the substrate carrier 132 due to manufacturing tolerances or damage, the thermal engagement element 120 is preferably dimensioned to extend far enough into the heating chamber 108 to cause compression of the substrate carrier 132 and thereby ensure an interference fit between the surface of the thermal engagement element 120 and the outer layer 142 of the substrate carrier 132. This compression of the substrate carrier 132 can also cause a longitudinal marking of the outer layer 142 of the substrate carrier 132 and provide a visual indication that the substrate carrier 132 has been used. Furthermore, the compression of the thermal engagement element 120 can also reduce any density variations of the aerosol substrate 134 and provide a more consistent and uniform distribution of the aerosol substrate 134 across the width of the substrate carrier 132. This can provide more effective and uniform heating.

[0137] As the thermal engagement elements 120 are provided to conduct heat to the aerosol substrate 134, it is preferable that the thermal engagement elements 120 are aligned with the region of the substrate carrier 132 containing the aerosol substrate 134 when the substrate carrier 132 is inserted into the heating chamber 108. As shown, the thermal engagement elements 120 are aligned with the aerosol substrate 134. Figure 8

[0138] It is preferable that a uniform number and arrangement of the thermal engagement elements 120 are provided, spaced evenly apart, such that the heating effect is evenly distributed. This has the additional effect of providing a centring force towards the central axis E on the substrate carrier 132. For example, in this example, the four thermal engagement elements 120, and the provision of the heating effect, also provides a certain centring effect to keep the substrate carrier 132 centred within the heating chamber 108. This can also improve the uniformity of the air flow around the substrate carrier 132, further improving the heating uniformity.

[0139] ​It has been found that as the aerosol substrate 134 is heated, the aerosol substrate 134 shrinks away from the thermal engagement elements 120 and the compression force used to maintain the substrate carrier 132 in the heating chamber 108 and prevent it from falling out is no longer optimal. Therefore, a plurality of gripping elements 122 are provided in accordance with the present disclosure, as described in greater detail below.

[0140] In this example, the inner diameter of the sidewall 114 is 7.6 mm. As the heating chamber 108 is adapted for use with a substrate carrier 132 of 7.0 mm diameter, this provides an approximately 0.3 mm gap on each side of the substrate carrier 132 from the sidewall 114. Each thermal engagement element 120 extends approximately 0.6 mm into the internal volume, contacting the aerosol substrate 134 within the substrate carrier 132 and compressing it approximately 0.3 mm on each side.

[0141] To be sure that the thermal engagement elements 120 contact the substrate carrier 132 (contact is necessary to cause conductive heating, compression, and deformation of the aerosol substrate), the manufacturing tolerances of each of the following are considered: the thermal engagement elements 120, the heating cavity 108, and the substrate carrier 132. For example, the inner diameter of the heating cavity 108 can be 7.6 ± 0.1 mm, the substrate carrier 132 can have an outer diameter of 7.0 ± 0.1 mm, and the thermal engagement elements 120 can have a manufacturing tolerance of ± 0.1 mm. In this example, assuming the substrate carrier 132 is installed centrally in the heating cavity 108 (i.e., leaving an even gap around the outside of the substrate carrier 132), the range of gaps that each thermal engagement element 120 must span in order to contact the substrate carrier 132 is 0.2 mm to 0.4 mm. In other words, since each thermal engagement element 120 spans a radial distance, the lowest possible value in this example is half the difference between the smallest possible heating cavity 108 diameter and the largest possible substrate carrier 132 diameter, or [(7.6 - 0.1) - (7.0 + 0.1)] / 2 = 0.2 mm. The upper end of the range in this example is (for similar reasons) half the difference between the largest possible heating cavity 108 diameter and the smallest possible substrate carrier 132 diameter, or [(7.6 + 0.1) - (7.0 - 0.1)] / 2 = 0.4 mm. To be sure that the thermal engagement elements 120 will certainly contact the substrate carrier 132, it is clear that in this example the thermal engagement elements must each extend at least 0.4 mm into the heating cavity 108. However, this does not take into account the manufacturing tolerance of the thermal engagement elements 120 themselves. When a 0.4 mm thermal engagement element 120 is desired, the range of actual production is 0.4 ± 0.1 mm or varies between 0.3 mm and 0.5 mm. Some of these protrusions will not span the maximum possible gap between the heating cavity 108 and the substrate carrier 132. Therefore, the thermal engagement elements 120 of this example should be produced with a nominal protruding distance of 0.5 mm, which results in a range of values between 0.4 mm and 0.6 mm. This is sufficient to ensure that the thermal engagement elements 120 will always contact the substrate carrier 132.

[0142] In general, the inner diameter of the heating cavity 108 is written as H ± δ H The outer diameter of the substrate carrier 132 is written as S ± δ S And the distance that the thermal engagement elements 120 extend into the heating cavity 108 is written as T ± δ T Then the distance that the thermal engagement elements 120 are intended to extend into the heating cavity 108 should be chosen as:

[0143]

[0144] Where |δ H | is the magnitude of the manufacturing tolerance of the inner diameter of the heating cavity 108, |δS | is the magnitude of the manufacturing tolerance of the outer diameter of the substrate carrier 132, and | δ T | is the magnitude of the manufacturing tolerance of the distance by which the thermal engagement elements 120 extend into the heating cavity 108. For the avoidance of doubt, in the case that the inner diameter of the heating cavity 108 is H ± δ H = 7.6 ± 0.1 mm, then | δ H | = 0.1 mm.

[0145] In some examples, additional extensions can be applied to ensure that the thermal engagement elements 120 not only contact the substrate carrier 132, but also ensure that they provide a certain degree of compression to the substrate carrier 132 to hold it securely and maintain contact even in the event that the aerosol substrate 134 shrinks when heated, for example, which can be represented by Δ in the following equation:

[0146]

[0147] Clearly, an addition of Δ can be suitably applied, and in the above example can correspond to a distance of approximately 0.1 mm. For example, to ensure a compression of at least 0.1 mm, the gripping elements 122 can be produced with a nominal depth of 0.6 mm, resulting in a range of 0.5 mm to 0.7 mm. It will be clear that this distance can be chosen to ensure the desired compression, and thus the contact of the thermal engagement elements, even when the aerosol substrate shrinks upon heating.

[0148] Furthermore, manufacturing tolerances can result in slight variations in the density of the aerosol substrate 134 within the substrate carrier 132. Such variations in the density of the aerosol substrate 134 can exist both in the axial and radial directions within a single substrate carrier 132, or between different substrate carriers 132 manufactured in the same batch. It will thus also be clear that, in order to ensure relatively uniform heat conduction within the aerosol substrate 134 within a particular substrate carrier 132, it is important to ensure that the density of the aerosol substrate 134 is also relatively consistent. To mitigate the effects of any inconsistencies in the density of the aerosol substrate 134, the dimensions of the thermal engagement elements 120 can be determined to extend far enough into the heating cavity 108 to compress the aerosol substrate 134 within the substrate carrier 132, which can improve heat conduction through the aerosol substrate 134 by eliminating air gaps. In the illustrated example, it is suitable for the thermal engagement elements 120 to extend approximately 0.4 mm into the heating cavity 108. In other examples, the distance by which the thermal engagement elements 120 extend into the heating cavity 108 can be defined as a percentage of the distance across the heating cavity 108. For example, the thermal engagement elements 120 can extend a distance of between 3% and 7%, for example approximately 5%, of the distance across the heating cavity 108.

[0149] With respect to the heat engagement elements 120, the width corresponds to the distance around the perimeter of the side wall 114. Similarly, its length direction is transverse thereto, generally extending from the base 112 of the heating chamber 108 to the open end or to the flange 116, and its depth corresponds to the distance that the heat engagement elements 120 extend from the side wall 114. It should be noted that the space between adjacent heat engagement elements 120, the side wall 114, and the outer layer 142 of the substrate carrier 132 defines an area through which air can flow. As a result, the smaller the distance between adjacent heat engagement elements 120 and / or the depth of the heat engagement elements 120 (i.e., the distance that the heat engagement elements 120 extend into the heating chamber 108), the more difficult it is for a user to draw air through the aerosol generating device 100 (referred to as increased draw resistance). Obviously, (assuming that the heat engagement elements 120 are in contact with the outer layer 142 of the substrate carrier 132), it is the width of the heat engagement elements 120 that defines the reduction in the air flow passage between the side wall 114 and the substrate carrier 132.

[0150] Conversely, (again assuming that the heat engagement elements 120 are in contact with the outer layer 142 of the substrate carrier 132), increasing the length of the heat engagement elements 120 results in more compression of the aerosol substrate 134, which eliminates air pockets in the aerosol substrate 134 and also increases the draw resistance.

[0151] These two parameters can be adjusted to give a satisfactory draw resistance, neither too low nor too high. The heating chamber 108 can also be made larger to increase the air flow passage between the side wall 114 and the substrate carrier 132, but there is a practical limit before the heat generator starts to fail due to the gap being too large. Typically, a gap of 0.2mm to 0.3mm around the outer surface of the substrate carrier 132 is a good compromise, which allows the draw resistance to be fine-tuned within acceptable values by varying the size of the heat engagement elements 120.

[0152] The air gap around the outside of the substrate carrier 132 can also be varied by varying the number of thermal engagement elements 120. Any number of thermal engagement elements 120 (from one upwards) provides at least some of the advantages set out herein (increasing the heating area, providing compression, providing conductive heating of the aerosol substrate 134, adjusting the air gap, etc.). Four is the lowest number that reliably maintains the substrate carrier 132 in centred (i.e. coaxial) alignment with the heating chamber 108. Designs with fewer than four thermal engagement elements 120 tend to allow for situations in which the substrate carrier 132 is pressed against a portion of the sidewall 114 between two thermal engagement elements 120. It will be apparent that for a limited space, providing a very large number of thermal engagement elements 120 (e.g. thirty or more) tends to situations in which there is little or no gap between them, which can completely close off the air flow path between the outer surface of the substrate carrier 132 and the inner surface of the sidewall 114, thereby greatly reducing the ability of the aerosol generating device 100 to provide convective heating. However, such designs can still be used in conjunction with the possibility of a hole in the centre of the base 112 defining an air flow passage. Typically, the thermal engagement elements 120 are evenly spaced around the circumference of the sidewall 114, which can help to provide even compression and heating, but some variations can have asymmetric placement depending on the exact effect desired.

[0153] It will be apparent that the size and number of thermal engagement elements 120 also allow for adjustment of the balance between conductive and convective heating. By increasing the width of the thermal engagement elements 120 (the distance that the thermal engagement elements 120 extend around the circumference of the sidewall 114) that contact the substrate carrier 132, the available circumference of the sidewall 114 that acts as an air flow passage is reduced, thus reducing the convective heating provided by the aerosol generating device 100. However, as the wider thermal engagement elements 120 are in contact with the substrate carrier 132 over a greater portion of the circumference, this increases the conductive heating provided by the aerosol generating device 100. Similar effects are seen if more thermal engagement elements 120 are added, as the circumference of the sidewall 114 available for convection is reduced, while the conductive pathway is increased by increasing the total contact surface area between the thermal engagement elements 120 and the substrate carrier 132. It should be noted that increasing the length of the thermal engagement elements 120 also reduces the volume of air in the heating chamber 108 that is heated by the heat generator and reduces convective heating, while increasing the contact surface area between the thermal engagement elements 120 and the substrate carrier 132 and increasing conductive heating. Increasing the distance that each thermal engagement element 120 extends into the heating chamber 108 can improve conductive heating without significantly reducing convective heating.

[0154] Accordingly, the aerosol generating device 100 can be designed to balance the conduction heating type and the convection heating type by varying the number and size of the thermal engagement elements 120, as described above. The heat concentration effect resulting from the relatively thin side wall 114 and the use of a material with a relatively low thermal conductivity (e.g. stainless steel) ensures that conduction heating is an appropriate way of transferring heat to the substrate carrier 132 and subsequently to the aerosol substrate 134, as the heated portion of the side wall 114 can substantially correspond to the location of the thermal engagement elements 120, meaning that the heat generated is conducted by the thermal engagement elements 120 to the substrate carrier 132, rather than away from here. In locations that are heated but do not correspond to the thermal engagement elements 120, the heating of the side wall 114 results in convection heating.

[0155] In this example, the thermal engagement elements 120 are elongate, that is to say, the length over which the thermal engagement elements extend is greater than their width. In some cases, the thermal engagement elements 120 can have a length that is five times, ten times or even twenty-five times their width. For example, as described above, the thermal engagement elements 120 can extend 0.4mm into the heating chamber 108, and in one example can further be 0.5mm wide and 12mm long. These dimensions are suitable for a heating chamber 108 that is between 30mm and 40mm in length, preferably 31mm. The thermal engagement elements 120 do not extend the entire length of the heating chamber 108, and are shorter in length than the side wall 114. Accordingly, the thermal engagement elements 120 each have a top edge and a bottom edge. The top edge is the portion of the thermal engagement element 120 that is closest to the first open end 110 of the heating chamber 108, and also closest to the flange 116. The bottom edge is the end of the thermal engagement element 120 that is closest to the base 112. Above the top edge (closer to the open end than the top edge) and below the bottom edge (closer to the base 112 than the bottom edge), the side wall 114 can be seen without the thermal engagement elements 120. In some examples, the thermal engagement elements 120 are longer, and extend all the way to the bottom of the side wall 114, adjacent to the base 112. Indeed, in such cases, there can not even be a bottom edge. The thermal engagement elements 120 do not extend to the first open end 110, but are spaced apart from the first open end 110. As described in more detail below, a plurality of gripping elements 122 are positioned between the thermal engagement elements 120 and the first open end 110. Preferably, there are no indentations between the thermal engagement elements 120 and the gripping elements 122, as Figure 5B shown.

[0156] At the upper end, the top edge of the thermal bonding element 120 can serve as an indicator, allowing the user to ensure that they do not insert the matrix carrier 132 too far into the aerosol generating device 100. Similarly, compression of the aerosol matrix 134 at the first end 138 of the matrix carrier 132 inserted into the heating chamber 108 may cause some aerosol matrix 134 to fall out of the matrix carrier 132 and soil the heating chamber 108. Therefore, it is advantageous to position the lower edge of the thermal bonding element 120 further from the base 112 than the intended position of the first end 138 of the matrix carrier 132.

[0157] In some examples, the thermal bonding element 120 is not elongated and has a width approximately the same as its length. For example, the width of the protrusion may be the same as its height (e.g., having a square or round profile when viewed in the radial direction), or the length of the protrusion may be two to five times its width. It should be noted that the centering effect provided by the thermal bonding element 120 can be achieved even when the thermal bonding element 120 is not elongated. However, to achieve the thermal bonding function desired herein, it is preferable that the thermal bonding element 120 provides a large contact surface area with the substrate carrier 132 to facilitate heat transfer. This is best provided by forming the thermal bonding element 120 into an elongated shape.

[0158] In the side view, as Figure 5B As shown, the thermally bonded element 120 is shown with a trapezoidal profile. That is, the upper edge is generally planar and tapers towards the first opening end 110 of the heating cavity 108, merging with the sidewall 114. In other words, the upper edge has a beveled profile. Similarly, the lower edge is generally planar and tapers towards the base 112 of the heating cavity 108, merging with the sidewall 114. That is, the lower edge has a beveled profile. In other examples, the upper and / or lower edges do not taper towards the sidewall 114, but extend at an angle of approximately 90° relative to the sidewall 114. In yet another example, the upper and / or lower edges have a curved or rounded shape. Bridging the upper and lower edges is a generally planar region that contacts and / or compresses the matrix carrier 132. The planar contact portion can help provide uniform compression and conductive heating. In other examples, the planar portion may instead be a curved portion that bends outward to contact the matrix carrier, for example having a polygonal or curved profile (e.g., a portion of a circle).

[0159] The upper edge of the thermal bonding element 120 can function to prevent the substrate carrier 132 from being over-inserted. For example... Figure 4As most clearly shown, the substrate carrier 132 has a lower portion comprising the aerosol substrate 134 that ends partway along the substrate carrier 132. The aerosol substrate 134 is generally more compressible than other regions of the substrate carrier 132, such as the aerosol collection region 136. Thus, as the compressibility of other regions of the substrate carrier 132 is reduced, a user inserting the substrate carrier 132 feels an increased resistance when the upper edge of the thermal engagement element 120 is aligned with the boundary of the aerosol substrate 134. To achieve this, the distance between the platform 118 of the base 112 that the substrate carrier 132 contacts and the top edge of the thermal engagement element 120 should be the same length as the aerosol substrate 134 occupies of the substrate carrier 132. In some examples, the aerosol substrate 134 occupies about 20mm of the substrate carrier 132, such that when the substrate carrier 132 is inserted into the heating cavity 108, the spacing between the top edge of the thermal engagement element 120 and the portion of the base that the substrate carrier contacts is also about 20mm. The upper edge can be bevelled to aid insertion of the substrate carrier 132 and to prevent damage to it as it is inserted, and to prevent puncturing of the outer layer 142, which is typically made of paper.

[0160] The heating cavity 108 comprises a plurality of gripping elements 122. The gripping elements 122 are formed on the inner surface of the side wall 114. The gripping elements 122 extend inwardly from the inner surface of the side wall 114 into the interior volume of the heating cavity 108 towards the central axis E. The gripping elements 122 are arranged to grip the substrate carrier 132 as it is inserted into the heating cavity 108.

[0161] The gripping elements 122 perform a different function to the thermal engagement element 120. When the thermal engagement element 120 contacts the substrate carrier 132 to conduct heat to the aerosol substrate 134, the gripping elements 122 are arranged to grip the substrate carrier 132 and are sized and shaped to reduce the effect of heat transfer to the substrate carrier.

[0162] The gripping elements 122 extend sufficiently into the heating chamber 108 to contact and preferably grip the substrate carrier 132 when it is inserted into the heating chamber 108. As mentioned above, the thermal engagement elements 120 extend into the internal volume to compress the substrate carrier 132 at the region containing the aerosol substrate 134. This provides good thermal contact to conduct heat from the heat generator into the aerosol substrate 134. However, the inventors have found that as the aerosol substrate 134 is heated, the aerosol substrate 134 tends to shrink in the substrate carrier 132. In particular, the aerosol substrate 134 shrinks away from the side wall 114 and effectively reduces its diameter. This can make contact with the thermal engagement elements 120 less uniform and less secure. Initially, the thermal engagement elements 120 can be arranged to extend into the internal volume and compress the aerosol substrate 134 to maintain sufficient contact to facilitate heat transfer. However, the shrinkage of the aerosol substrate 134 can reduce the effectiveness of this engagement, such that the substrate carrier 132 is not optimally held in place. For example, if the aerosol generating device 100 is held upside down, or if the substrate carrier sticks to a user's lips, this can allow the substrate carrier 132 to be inadvertently removed, or cause the aerosol substrate 134 to become misaligned with the heating components.

[0163] It is not preferred to set the thermal engagement elements 120 to extend further into the internal volume to compensate for this, as this further restricts airflow into the heating chamber 108 and also reduces the area available for insertion of the substrate carrier 132 prior to heating and shrinkage. Therefore, it is preferred to limit the amount of extension of the thermal engagement elements 120 into the internal volume of the heating chamber 108 to ensure that airflow is not restricted. Furthermore, when the substrate carrier 132 is inserted in this configuration, the aerosol substrate 134 is compressed to a reduced diameter set by the extended thermal engagement elements 120 and will further shrink once heated. It is desirable to avoid the aerosol substrate 134 being overly compressed to allow airflow through the aerosol substrate 134.

[0164] It has been found that by providing a plurality of separate gripping elements 122 according to the present disclosure, the substrate carrier 132 can be securely held in place independently of the thermal engagement elements 120. In particular, the gripping elements 122 provide additional grip without impeding airflow. This is particularly achieved when the gripping elements 122 are arranged to overlap with a region of the substrate carrier 132 that is thermally stable and does not shrink when the substrate carrier 132 is heated, as described below. The exact position of the gripping elements 122 in the heating chamber 108 is not critical, provided that they align with a portion of the substrate carrier 132 that is thermally stable and does not shrink, such as the aerosol collection region 136.

[0165] In this example, the side wall 114 has a length of 31 mm. The gripping elements 122 are spaced apart from the first open end 110 of the heating cavity 108 by a distance of 4 mm along the length of the side wall 114. The gripping elements 122 are spaced apart from the heat engagement elements 120 by approximately 5 mm. Due to the thin side wall 114 and the small contact area of the gripping elements, heat transfer along the side wall 114 is limited, which means that very little heat is transferred towards the first open end 110 to the gripping elements 122. This reduces heat transfer through the gripping elements 122, thereby reducing undesirable heating of the gripping elements 122, which typically contact the parts of the substrate carrier 132 that do not contain aerosol substrate 134.

[0166] The length of the gripping elements 122 is parallel to the length of the side wall 114, generally in the direction from the base 112 to the first open end 110 of the heating cavity 108. The gripping elements 122 have a width around the circumference of the side wall 114. The depth of the gripping elements 122 is the extent to which they extend radially inwards into the internal volume of the heating cavity 108.

[0167] The gripping elements 122 extend into the internal volume of the heating cavity 108. The gripping elements 122 extend less into the internal volume than the heat engagement elements 120. This is to accommodate the difference in stiffness of the substrate carrier in the different regions that these elements press against.

[0168] It can be seen from Figure 5B that the innermost part of each heat engagement element 120 is positioned at a radial distance R2 from the central axis E. Similarly, each gripping element 122 is positioned at a radial distance R1 from the central axis E. In this example, the gripping elements 122 extend a shorter radial distance into the internal volume than the heat engagement elements 120. In other words, R1 > R2.

[0169] Another way to look at this is to consider the circumference of the heating cavity 108 (i.e. the length around the perimeter in a plane perpendicular to the central axis E). The circumference of the heating cavity 108 in the region where there are no gripping elements 122 or heat engagement elements 120 serves as a baseline circumference. The baseline circumference has a characteristic dimension (referred to here as the diameter) which is the shortest distance extending through the central axis E across the heating cavity 108. For a cylindrical heating cavity 108, the circumference is a circle and the diameter has the usual meaning with respect to a circle. For a heating cavity 108 with an elliptical cross-section, the diameter is twice the semi-minor axis. For a heating cavity 108 with a square or rectangular cross-section, the diameter is the distance across the heating cavity 108, perpendicular to the side wall 114, between opposite (longest) sides. Other shapes are possible and have a circumference and diameter definition consistent with this description.

[0170] In the case where the sidewall 114 has been deformed inward to create the gripping element 122 or the thermal engagement element 120, the circumference around the wall is no longer a simple shape, and is also typically made longer by the curvature introduced by the deformation. However, a first limiting circumference can be defined as a maximum shape similar to the baseline circumference (i.e. the same shape and orientation, but different in size), which can be fitted into the heating cavity 108 along the length, in the region aligned with the gripping element 122, such that the first limiting circumference just touches the innermost part of the gripping element 122. Figure 6B Such a first limiting circumference is shown in dashed line in FIG. 12. Similarly, a second limiting circumference can be defined as a maximum shape similar to the baseline circumference (i.e. the same shape and orientation, but different in size), which can be fitted into the heating cavity 108 along the length, in the region aligned with the thermal engagement element 120, such that the second limiting circumference just touches the innermost part of the thermal engagement element 120. Figure 6C Such a second limiting circumference is shown in dashed line in FIG. 13.

[0171] The first and second limiting circumferences have corresponding first and second limiting diameters, which are defined analogously to the diameters with respect to the baseline circumference set out above. Thus, the cylindrical heating cavity 108 has circular first and second limiting circumferences and first and second limiting diameters in the usual sense with respect to a circle. For a heating cavity 108 with an elliptical cross-section, the first and second limiting diameters are also elliptical (with the same eccentricity), and the first and second limiting diameters are diameters which are twice the semi-minor axis of their respective ellipse. For a heating cavity 108 with a square or rectangular cross-section, each limiting circumference is also (respectively) a square or rectangle with the same relative side lengths and orientation. The first and second limiting diameters are the distances across the heating cavity 108, perpendicular to the sidewall 114, between the opposite (longest) sides, with respect to their respective limiting circumferences. Other shapes can be seen to conform to this general pattern.

[0172] In Figure 5B , Figure 6B and Figure 6C Examples are shown in FIGS. 12 and 13, where the baseline diameter is simply the distance across the heating cavity 108, for example under the thermal engagement element 120 (or between the thermal engagement element 120 and the gripping element 122). The radial distance R1 between the central axis E and the innermost part of the gripping element 122 corresponds to half of the first limiting diameter. In other words, the first limiting diameter is 2x R1. Similarly, it is seen that the radial distance R2 between the central axis E and the innermost part of the thermal engagement element 120 corresponds to half of the second limiting diameter. In other words, the second limiting diameter is 2x R2.

[0173] In this example, since the heating chamber 108 is cylindrical, the baseline circumference and the first and second limiting circumferences are all circles. The radii of the latter two circles are R1 and R2, respectively. As discussed above, the thermal engagement elements 120 extend further into the interior volume of the heating chamber 108 than the gripping elements 122. This means that the first limiting diameter is greater than the second limiting diameter. In other words, the first limiting circumference is a circle that is larger (longer in circumference and encloses a larger area) than the circle of the second limiting circumference. It will be seen that these observations remain true for tubular heating chambers 108 of a wide variety of cross-sectional shapes, in which the gripping elements 122 extend less far into the interior volume of the heating chamber 108 than the thermal engagement elements 120.

[0174] Ideally, the thermal engagement elements 120 extend a distance of about 0.1 mm to 0.2 mm further into the interior volume of the heating chamber 108 than the gripping elements 122. Another way to look at it is that the first limiting diameter can be 64 mm, while the substrate carrier 132 has an outer diameter of 70 mm, so the gripping elements 122 compress each side of the substrate carrier by 3 mm. In contrast, for a substrate carrier 132 outer diameter of 70 mm, the second limiting diameter can be 62 mm, so that each side is compressed by the thermal engagement elements by 4 mm. This increased compression can help maintain contact between the thermal engagement elements 120 and the outer surface of the substrate carrier 132 in the event of shrinkage as the aerosol substrate 134 is heated.

[0175] This means that the gripping elements 122 do not restrict the cross-section of the heating chamber 108, and so do not restrict the airflow any more than the thermal engagement elements 120. In some cases, the profile of the gripping elements 122 in a plane perpendicular to the length of the side wall 114 that blocks a portion of the interior volume is equal to the profile of the thermal engagement elements 120. In other words, each gripping element 122 has an innermost part for contacting the substrate carrier 132, and these innermost parts are all located at the same radial distance from the central axis E of the heating chamber 108.

[0176] Since the gripping elements 122 are preferably arranged to align with parts of the substrate carrier 132 that are not the aerosol substrate 134, such as the aerosol collection region 136 in the form of a paperboard tube, the gripping elements 122 are in contact with parts that are more robust and less compressible than the aerosol substrate 134 and do not shrink during heating. Therefore, better contact can be maintained, and the gripping elements 122 do not have to extend as far into the interior volume as the thermal engagement elements 120. In some examples, the aerosol collection region 136 can include suitable notches for engaging the gripping elements 122 to help the user position the substrate carrier 132 within the heating chamber 108, for example by knocking it into place.

[0177] Using the above example with a substrate carrier 132 having a 7.0 mm diameter and a 7.6 mm inner diameter of the sidewall, the gap of each side of the substrate carrier 132 to the sidewall 114 is about 0.3 mm. To contact the substrate carrier 132, the depth of the gripping element 122 is selected to be at least 0.3 mm. That is, the gripping element 122 extends at least 0.3 mm into the interior volume toward the central axis E.

[0178] As with the thermal engagement element 120, the amount of manufacturing tolerance should be considered. For example, the inner diameter of the heating cavity 108 can be 7.6 ± 0.1 mm, the substrate carrier 132 can have an outer diameter of 7.0 ± 0.1 mm, and the thermal engagement element 120 can have a manufacturing tolerance of ± 0.1 mm. In the same manner as above, the minimum value of the depth of the gripping element 122 is 0.2 mm, and the maximum value is 0.4 mm. Thus, when the variations of the heating cavity 108 and the substrate carrier 132 are considered, the depth of the gripping element 122 must be at least 0.4 mm to guarantee contact. When the tolerance of the gripping element 122 itself is considered, the range is 0.4 mm ± 0.1 mm (i.e., 0.3 mm to 0.5 mm). To ensure contact, the gripping element 122 must be produced with a nominal depth of 0.5 mm, resulting in a range of values between 0.4 mm and 0.6 mm. This is sufficient to ensure that the gripping element 122 will always be in contact with the substrate carrier 132.

[0179] As described above, the inner diameter of the heating cavity 108 is written as H ± δ H The outer diameter of the substrate carrier 132 is written as S ± δ S and the distance that the gripping element 122 extends into the heating cavity 108 is written as G ± δ G Then the distance that the gripping element 122 is intended to extend into the heating cavity 108 should be selected as:

[0180]

[0181] where |δ H | refers to the magnitude of the manufacturing tolerance of the inner diameter of the heating cavity 108, |δ S | refers to the magnitude of the manufacturing tolerance of the outer diameter of the substrate carrier 132, and |δ G | refers to the magnitude of the manufacturing tolerance of the distance that the gripping element 122 extends into the heating cavity 108. For the avoidance of doubt, in the case where the inner diameter of the heating cavity 108 is H ± δ H = 7.6 ± 0.1 mm, then |δ H | = 0.1 mm.

[0182] The gripping elements 122 have a length extending along the length of the side wall 114 which is less than 5 mm, preferably less than 3 mm, more preferably less than 2 mm, still more preferably less than 1 mm. The length of the gripping elements 122 is preferably less than 20%, more preferably less than 10%, still more preferably less than 5% of the length of the side wall 114 compared to the length of the side wall 114. Overall, the gripping elements 122 are arranged for gripping, but not to transfer heat to parts of the substrate carrier 132 which do not need to be heated. This is best achieved with smaller gripping elements to minimise the contact surface area.

[0183] These gripping elements 122 can be formed as embossed indentations formed in the outer wall of the heating cavity 108. Figure 6D A detailed view of such a gripping element 122 is shown in Figure 6B highlighted as part P. This design provides limited heat transfer, but a firm gripping action. The gripping elements 122 can be a curved innermost part of the side wall connected at the circumference, which is substantially circular, elliptical, square or rectangular. The tip of the gripping element (innermost inner part) is preferably rounded or flat to avoid poking through the surface of the substrate carrier (e.g. tipping paper). For example, the gripping elements 122 can form a partly elliptical, hemispherical, or trapezoidal profile at their innermost part in a plane parallel to the length of the heating cavity. The gripping elements 122 are formed in the outer surface of the heating cavity and can have a cavity comprising a substantially hemispherical innermost part and an annular outermost part connecting the tubular side wall. The annular outermost part can be connected to the side wall by a slightly curved part (e.g. with a radius of about 0.1 mm). For example, the outermost part can have a diameter of between 0.3 and 1 mm, preferably between 0.4 and 0.7 mm, e.g. 0.6 mm, while the hemispherical innermost part can have a radius of e.g. about 0.15 mm.

[0184] The length of the heat engaging elements 120 is greater than the length of the gripping elements 122. In particular, the length of the heat engaging elements 120 is at least twice, preferably at least three times, more preferably at least five times, still more preferably at least ten times the length of the gripping elements 122. It is preferred that the heat engaging elements 120 are longer to have a longer surface in contact with the aerosol substrate 134 to facilitate heat transfer to the aerosol substrate 134, and it is preferred to reduce the surface of the gripping elements 122 in contact with the substrate carrier 132 to reduce heat transfer to areas not containing aerosol substrate 134.

[0185] Referring to Figure 5B , Figure 6A and Figure 6BThe gripping elements 122 are arranged around the circumference of the sidewall 114. The plurality of gripping elements 122 are arranged such that each gripping element 122 is located at a different position around the circumference of the sidewall 114. See Figure 6A and Figure 6B Four gripping elements 122 are shown, but other suitable numbers of gripping elements 122 are contemplated. The four gripping elements 122 are equally spaced around the circumference of the sidewall 114. This allows the substrate carrier 132 to be securely held within the heating cavity 108 by the gripping elements 122. Providing equally spaced gripping elements 122 can also help to center the substrate carrier 132 within the heating cavity 108, especially when the gripping elements 122 are the same size and shape as each other. Similar to the centering effect of the thermal engagement elements 120, four gripping elements 122 is the minimum number that reliably holds the substrate carrier 132 centered (i.e., coaxially) aligned with the heating cavity 108. Designs with fewer than four gripping elements 122 tend to allow the substrate carrier 132 to press against the portion of the sidewall 114 between two adjacent gripping elements 122, and this can squeeze the substrate carrier 132 toward some of the thermal engagement elements 120 and away from others, resulting in uneven heating and uneven air flow paths. In other cases, providing two gripping elements 122 can be sufficient, but this depends on the degree of contact with the thermal engagement elements 120 needed to assist in supporting the substrate carrier 132 in place.

[0186] Each of the gripping elements 122 extends partially along the inner circumference of the sidewall 114. In this example, since the sidewall 114 is circular, each of the gripping elements 122 extends partially along the inner circumference of the sidewall 114. See Figure 6A and Figure 6B Each of the gripping elements 122 extends only a small segment around the sidewall 114. In particular, each of the gripping elements 122 extends approximately 1 mm around the circumference of the sidewall 114. In this example, for a 7.6 mm inner diameter of the heating cavity 108, the four gripping elements 122 collectively overlap 4 mm along a 23.9 mm circumference. Preferably, the total proportion of the circumference covered by the gripping elements 122 is no more than 20%, more preferably no more than 10%. This prevents the gripping elements 122 from overly restricting air flow into the heating cavity 108 between the substrate carrier 132 and the sidewall 114. In some examples, the gripping elements 122 have a length that is approximately the same as their height. In any case, the circumferential extent of the gripping elements 122 should not be greater than the circumferential extent of the thermal engagement elements 120, so that the gripping elements 122 do not restrict air flow more than the thermal engagement elements 120 already do. Thus, the gripping elements 122 are preferably angularly aligned with and have the same width as the thermal engagement elements 120.

[0187] Preferably, the gripping elements 122 are evenly spaced around the circumference of the sidewall 114, which can centrally position the substrate carrier 132 within the heating cavity 108 and allow for uniform air flow paths to be obtained around the substrate carrier 132.

[0188] In this example, the gripping elements 122 are aligned with the thermal engagement elements 120 along the length of the sidewall 114. The gripping elements 122 are arranged at locations aligned with the thermal engagement elements 120, but spaced apart from the thermal engagement elements 120 along the length of the sidewall 114. The gripping elements 122 extend into the interior volume no more than the amount of the thermal engagement elements 120. Additionally, the gripping elements 122 extend around the circumference no more than the amount of the thermal engagement elements 120. This means that the gripping elements 122 do not protrude further into the interior volume than the thermal engagement elements 120, and do not interfere with air flow into the heating cavity 108.

[0189] In an alternative example, as shown in FIG. 12, the gripping elements 122 can not be aligned with the thermal engagement elements 120 along the length of the sidewall 114 to force air flow over the thermal engagement elements 120. Figure 10

[0190] However, in some examples, it is preferred to have different profiles to tailor each set of elements to its particular function. For example, in this example, the gripping elements 122 have a rounded profile in a plane perpendicular to the length of the sidewall 114 to grip the substrate carrier 132, while the thermal engagement elements 120 have a trapezoidal shape with the innermost facing flattened surface facing towards the center axis E in the interior volume to present a larger surface area for contacting the substrate carrier 132.

[0191] The gripping elements 122 have a convex profile in a cross-section perpendicular to the length of the sidewall 114. In other words, the gripping elements 122 extend from the sidewall 114 into the interior volume to reduce the effective cross-sectional area of the heating cavity 108.

[0192] Broadly, the gripping elements 122 have a portion with a decreasing area towards the interior volume of the heating cavity 108. That is, the gripping elements 122 narrow from the sidewall 114 towards the interior volume, towards the center axis E. In this example, the gripping elements 122 have a generally rounded cross-section in a plane perpendicular to the length of the sidewall 114. As shown in FIG. 10, the gripping elements 122 have a rounded profile extending from the sidewall 114. Additionally, in this example, the gripping elements 122 have a generally circular cross-section in a plane parallel to the length of the sidewall 114, as shown in FIG. 11. Figure 6A Figure 6B Figure 5B ​​​The gripping element 122 of this example forms part of a sphere, and in particular a semi-sphere extending from the side wall 114. In this case, the gripping element 122 extends into the interior volume of the heating chamber 108 by substantially the same distance as its length along the side wall 114, and by substantially the same distance as its width around the circumference of the side wall 114. It will be appreciated that other shapes are possible, and that the length need not be the same as the width, and neither the length nor the width need be the same as the depth.

[0193] The spherical shape provides the necessary extension into the interior volume for the gripping substrate carrier 132, but reduces the area towards the interior volume to ensure that there is not too much surface area, reducing the likelihood of any unwanted heat transfer to the substrate carrier 132. As such, preferably the gripping element 122 has a rounded edge at the innermost point of the gripping element 122, which is the part of the gripping element 122 that faces the interior volume and is configured to contact the substrate carrier 132. In alternative examples, the gripping element 122 can have a sharp edge to further reduce the contact area, and more provide a pinching effect, as Figure 12 illustrated.

[0194] The gripping element 122 provides an upper surface facing the first open end 110, which is inclined from the side wall 114 towards the central axis E. In other words, the gripping element 122 tapers from the side wall 114 closest to the first open end 110 towards the interior volume. This means that the gripping element 122 effectively reduces the diameter of the side wall 114 in a direction from the first open end 110 towards the base 112. This provides a ramp for the substrate carrier 132 to first contact within the heating chamber 108 and can make it easier for a user to insert the substrate carrier 132, and prevent the substrate carrier 132 from being damaged or punctured. In this example, the ramp is provided by the spherical surface of the gripping element 122. It will be appreciated that the ramp can have other shapes, such as a triangular, trapezoidal, or other inclined or rounded shape.

[0195] The gripping element 122 can also be used to help a user position the substrate carrier 132 within the heating chamber 108. Consider Figure 8In the illustrated example, with the boundary of the aerosol substrate 134 and the aerosol collection region 136 aligned with the upper edge of the thermal engagement element 120, when the user inserts the substrate carrier 132, the aerosol substrate 134 is generally more compressible than the aerosol collection region 136 and deforms around the gripping elements 122. As the substrate carrier 132 is inserted further, the user feels a resistance from the aerosol collection region 136 abutting the gripping elements 122. The slope of the upper surface of the gripping elements 122 helps to guide the insertion while providing a tangible resistance to the user. The user can continue to insert the substrate carrier 132 until the aerosol collection region 136 abuts the upper edge of the thermal engagement element 120, at which point the user feels a second resistance. This informs the user that the substrate carrier 132 is fully inserted and cannot be pushed too hard against the base 112 or the platform 118, which can help to prevent damage.

[0196] The gripping elements 122 are generally the same shape as each other, as this can help to provide a uniform grip of the substrate carrier 132 and its centring within the heating chamber 108. However, it will be appreciated that different shaped gripping elements 122 can be provided and individual gripping elements 122 of different shapes can be used in the same heating chamber 108. Additionally, the gripping elements 122 can be generally the same size as each other. For example, each gripping element 122 can have the same length and / or width and / or depth.

[0197] In this example, there are the same number of gripping elements 122 as there are thermal engagement elements 120 (i.e. four). In other examples, there can be a different number of gripping elements 122 than there are thermal engagement elements 120.

[0198] In some examples, the gripping elements 122 can be provided with any of the features mentioned above in relation to the thermal engagement elements 120. In particular, as the gripping elements 122 can be deformed by the side wall 114 in the same way as the thermal engagement elements 120, a similar shape can be provided, although, as mentioned, due to the different function, it is preferable to have a different size. As a further example, the upper edge of the gripping elements 122 can be used to guide the insertion of the substrate carrier 132 in the same way as described above in relation to the thermal engagement elements 120.

[0199] The gripping element 122 is formed from a portion of the side wall 114. In other words, the gripping element 122 is integral with the side wall 114 of the heating chamber 108. In this example, the gripping element 122 is formed from a deformed portion of the side wall 114. For example, the gripping element 122 can be embossed from the side wall 114. The gripping element 122 is an indentation formed by deforming a portion of the side wall 114 towards the interior volume of the heating chamber 108. Thus, the gripping element is preferably not formed from an additional element attached to the side wall 114. Thus, there is no unnecessary thickness added to the side wall 114. This provides the desired function of the gripping element 122 without increasing the thermal mass of the heating chamber 108. If the thermal engagement element 120 is also deformed in the same way, this process can be performed in the same step or in a plurality of adjacent steps.

[0200] Turning to Figure 8 The arrangement of the gripping element 122 relative to the substrate carrier 132 is shown in more detail. In this example, the gripping element 122 is configured to align with a portion of the substrate carrier 132 that does not contain the aerosol substrate 134. In particular, the gripping element 122 aligns with the aerosol collection region 136 when the substrate carrier 132 is inserted. The aerosol collection region 136 is typically a hollow tube made of paperboard or acetate and the like. The aerosol collection region 136 provides a region that allows aerosol to collect and allows the vapour to cool and mix with air before being inhaled by the user once the aerosol is released from the aerosol substrate 134. The aerosol collection region 136 is typically more incompressible than the aerosol substrate 134 and thus the gripping element 122 can provide a greater grip than against the aerosol substrate 134. Furthermore, as the aerosol collection region 136 does not shrink during heating, the gripping element 122 can maintain the grip even after heating.

[0201] Referring to Figure 9The heating chamber 108 is shown with a heat generator wrapped around it. In this example, the heat generator is an electrical heat generator. The heat generator is in the form of an electrically insulating backing layer 154, for example a polyimide film, with an electrically conductive heating element 156, such as a copper track. The material of the heating element 156 can be selected to have a desired electrical resistance and therefore a desired power output. As used herein, "heat generator", for example heat generator, refers to the entire heating component (heating element 156 and backing layer 154), whereas "heat generator" refers to the heating track or heating element 156. As described herein, the heat generator is arranged to overlap the central portion of the side wall 114, and not to overlap at the end towards the first open end 110 and at the end towards the base 112. In particular, the heat generator is arranged to overlap the entire length of the thermal engagement element 120. This directly provides heat to the side wall 114 of the heating chamber 108 in the vicinity of the thermal engagement element 120. The thermal engagement element 120 can therefore efficiently conduct heat to the aerosol substrate 132.

[0202] The heat generator is arranged not to overlap the gripping element 122. In other words, the heat generator is not arranged at the location of the side wall 114 where the gripping element 122 is arranged. That is, there is a gap along the length of the side wall 114 between the location of the gripping element 122 and the location at which the heat generator is arranged. The gripping element 122 is therefore not in contact with the heat generator. As mentioned above, this ensures that heat is directed to the thermal engagement element 120 to conduct heat to the aerosol substrate 134, and prevents the gripping element 122 from being heated, thereby improving heating efficiency.

[0203] As mentioned above, optionally, there can be a metal layer between the outer surface of the side wall 114 and the heat generator. For example, this can be an electroplated layer of a high thermal conductivity metal, such as copper, to improve heat transfer efficiency.

[0204] In some examples, the backing layer 154 can extend a greater area than the heating element 156. For example, the heat generator can be arranged along the side wall such that the heating element 156 significantly covers the length of the thermal engagement element 120, but the backing layer 154 extends further and can in fact overlap the gripping element 122. This does not provide a significant heating effect to the gripping element 122, and should not be considered a case where the heat generator overlaps the gripping element 122. In other words, when the heat generator is arranged not to overlap the gripping element 122, this means that the heating element 156 is spaced apart from the gripping element 122, but in some cases the backing layer 154 of the heat generator can overlap the gripping element 122. Functionally, it is desirable that the gripping element 122 is not heated by the heat generator, thereby improving heating efficiency.

[0205] In alternative examples, the heat generator can at least partially overlap with the gripping element 122. For example, the heat generator can cover the gripping element 122. This can be advantageous in some cases as it can provide a heating effect to the aerosol collection region 136 through the gripping element 122. This heat transfer can prevent aerosol from condensing in the aerosol collection region 136. In some examples, it can be used to heat not only the region of the substrate carrier 132 containing the aerosol substrate 134, but also other regions. This is because once aerosol is generated, it is advantageous to keep its temperature high (above room temperature, but not so high as to burn the user) to prevent recondensation, which in turn would reduce the user experience.

[0206] Turning to Figure 8 When the substrate carrier 132 is inserted into the heating chamber 108, the substrate carrier 132 is in contact with the thermal engagement element 120. The thermal engagement element 120 primarily provides thermal contact between the heating chamber 108 and the substrate carrier 132 and is configured for efficient conduction of heat from the heat generator to the substrate carrier 132. To this end, it is preferred that the thermal engagement element 120 is substantially aligned with at least a portion of the aerosol substrate 132 within the substrate carrier 132. For example, see Figure 8 When the substrate carrier 132 is inserted into the heating chamber 108, the portion of the substrate carrier 132 containing the aerosol substrate 134 is in contact with the thermal engagement element 120.

[0207] In other examples, the portion of the aerosol substrate 134 at the first end 138 of the substrate carrier 132, adjacent to the base 112, can not be aligned with the thermal engagement element 120 to reduce or inhibit heating of the substrate at the first end 138. The substrate carrier 132 is supported at the first end 138 by resting on the platform 118 in the base 112 of the heating chamber 108. As described above, the platform 118 is raised in the central region above the base 112, providing a space around the platform 118 that spaces the substrate carrier 132 from the base 112. This reduces direct heating of the first end 138. It also facilitates air flow into the first end 138.

[0208] In this example, the boundary between the aerosol substrate 134 and the aerosol collection region 136 is arranged to be substantially aligned with the upper surface of the thermal engagement element 120 when the substrate carrier 132 is inserted. This can provide a seal to retain heat and vapour and prevent the aerosol collection region, which does not produce aerosol, from being heated.

[0209] When the substrate carrier 132 is inserted into the heating chamber 108, the gripping elements 122 are configured to contact the substrate carrier 132 at a point between the aerosol substrate 134 and the second end 140. In other words, the gripping elements 122 are positioned to contact the substrate carrier 132 at a location that does not overlap with the aerosol substrate 134. In this example, the gripping elements 122 are arranged to contact the substrate carrier 132 at the aerosol collection region 136. In this way, the gripping elements 122 can grip the aerosol substrate 134 at a location that does not interfere with the heating of the aerosol substrate 134. Furthermore, as the aerosol substrate 134 is heated, it begins to shrink and reduce contact with the thermal engagement elements 120. This does not significantly affect the ability of the thermal engagement elements 120 to heat the aerosol substrate 134, and the heat via convection is not hindered in any case, but it can result in less secure engagement between the thermal engagement elements 120 and the aerosol substrate 134 as the aerosol substrate 134 shrinks away from the thermal engagement elements 120. Therefore, by providing the gripping elements 122 at a location away from the aerosol substrate 134, the substrate carrier 132 can be secured in place regardless of any shrinkage of the aerosol substrate 134 during heating.

[0210] It is therefore recognised that there is provided a heating chamber 108 for an aerosol generating device 100, the heating chamber 108 comprising: a first open end 110 through which a substrate carrier 132 containing an aerosol substrate 134 is insertable in a direction along a length of the heating chamber 108; a side wall 114 defining an interior volume of the heating chamber 108; a plurality of thermal engagement elements 120 for contacting the substrate carrier 132 and providing heat thereto, each thermal engagement element 120 extending inwardly from an inner surface of the side wall 114 into the interior volume at a different location around the side wall 114; and a plurality of gripping elements 122 spaced along the length of the side wall 114 from the thermal engagement elements 120, each gripping element 122 extending inwardly from the inner surface of the side wall 114 into the interior volume at a different location around the side wall 114, wherein the gripping elements 122 are located closer to the first open end 110 than the thermal engagement elements 120.

[0211] Referring to Figure 10 and Figure 11 another example of a heating chamber 108 is shown in which the gripping elements 122 are not aligned with the thermal engagement elements 120 along the length of the side wall 114. It will be appreciated that the orientation in which the gripping elements 122 and the thermal engagement elements 120 are arranged in this way still results in a functionally good aerosol generating device 100.

[0212] Referring to Figure 12A further example of a heating chamber 108 is shown with a cross-sectional view through the gripping element 122. Here, the gripping element 122 is shown to have a triangular profile in a plane perpendicular to the length of the side wall 114. This profile can in particular be adapted for gripping the substrate carrier 132 to prevent relative movement between the substrate carrier 132 and the aerosol generation device 100. The gripping element 122 shown here is formed by a deformation of the side wall 114 and thus has the same thickness as the side wall 114.

Claims

1. A heating chamber (108) for an aerosol generation device (100), the heating chamber (108) comprising: a first open end (110) through which a substrate carrier (132) containing an aerosol substrate (134) is insertable in a direction along a length of the heating chamber (108); a side wall (114) defining an interior volume of the heating chamber (108); a plurality of thermal engagement elements (120) for contacting the substrate carrier (132) and providing heat thereto, each thermal engagement element (120) extending inwardly from an inner surface of the side wall (114) into the interior volume at a different location around the side wall (114); and a plurality of gripping elements (122) spaced apart from the thermal engagement elements (120) along the length of the side wall (114), each gripping element (122) extending inwardly from an inner surface of the side wall (114) into the interior volume at a different location around the side wall (114); wherein the gripping elements (122) are located closer to the first open end (110) than the thermal engagement elements (120), wherein the heating chamber (108) has a central axis along which the substrate carrier (132) is insertable; wherein, the gripping elements (122) each have an innermost portion for gripping the substrate carrier (132) located at a first radial distance from the central axis; and the thermal engagement elements (120) each have an innermost portion for contacting the substrate carrier (132) located at a second radial distance from the central axis; the first radial distance being greater than the second radial distance.

2. The heating chamber of claim 1, wherein, The thermal engagement elements (120) comprise a deformed portion of the side wall (114).

3. The heating chamber of claim 1 or 2, wherein, The side wall (114) has a constant thickness.

4. The heating chamber of claim 3, wherein, The constant thickness is less than 1.2 mm.

5. The heating chamber of claim 1, wherein, The side wall (114) is formed from metal.

6. The heating chamber of claim 1, wherein, The thermal engagement elements (120) comprise an embossed portion of the side wall (114).

7. The heating chamber of claim 1, wherein, The first radial distance is at least 0.05 mm greater than the second radial distance.

8. The heating chamber of claim 7, wherein, The first radial distance is between 0.1 mm and 0.5 mm greater than the second radial distance.

9. The heating chamber (108) of claim 1, wherein, The thermal engagement elements (120) and the gripping elements (122) are formed as a single integral part of the side wall (114).

10. The heating chamber (108) of claim 1, wherein, The thermal engagement elements (120) have a profile in a plane parallel to the length of the heating chamber (108) that is different to a profile of the gripping elements (122) in a plane parallel to the length of the heating chamber (108).

11. The heating chamber (108) of claim 1, wherein, The thermal engagement elements (120) have the same shape as each other.

12. The heating chamber (108) of claim 1, wherein, The gripping elements (122) have the same shape as each other.

13. The heating chamber (108) of claim 1, wherein, The number of thermal engagement elements (120) is the same as the number of gripping elements (122).

14. The heating chamber (108) of claim 1, wherein, The thermal engagement elements (120) extend a first distance along the length of the side wall (114) and the gripping elements (122) extend a second distance along the length of the side wall (114), wherein the first distance is greater than the second distance.

15. The heating chamber (108) of claim 1, wherein, At least one of the gripping elements (122) has a pointed or rounded profile that extends inward into the interior volume.

16. The heating chamber (108) of claim 15, wherein, The pointed profile is triangular, or the rounded profile is a portion of a sphere.

17. The heating chamber (108) of claim 1, further comprising a heat generator arranged to provide heat to the substrate carrier (132).

18. The heating chamber (108) of claim 17, wherein, The heat generator is positioned to extend a fifth distance along the sidewall (114) such that at least a portion of the heat generator is positioned adjacent to at least a portion of the sidewall (114) corresponding to a location of the thermal engagement elements (120).

19. The heating chamber (108) of claim 18, wherein, The heat generator is positioned such that the heat generator is not adjacent to any portion of the sidewall (114) corresponding to a location of the gripping elements (122).

20. The heating chamber (108) of claim 1, further comprising a base (112) at a second end of the sidewall (114) opposite the first open end (110).

21. The heating chamber (108) of claim 1, further comprising the substrate carrier (132), the substrate carrier (132) having a first portion and a second portion, wherein, The first portion is positioned further from the first open end (110) than the second portion when the substrate carrier (132) is inserted into the heating chamber (108), and wherein the first portion comprises aerosol substrate (134).

22. The heating chamber (108) of claim 21, wherein, The thermal engagement elements (120) are arranged to contact a first portion of the substrate carrier (132).

23. The heating chamber (108) of claim 21, wherein, The gripping elements (122) are arranged to grip a second portion of the substrate carrier (132).

24. The heating chamber (108) of claim 21, wherein, The second portion does not contain aerosol substrate (134).

25. An aerosol generation device (100), comprising: a power supply (126) ； a heating chamber (108) according to claim 1; a heat generator arranged to provide heat to the heating chamber (108); control circuitry (128) configured to control supply of electrical power from the power supply (126) to the heat generator; and an outer housing (102) enclosing the power supply (126), the heating chamber (108), the heat generator, and the control circuitry (128), wherein, The outer housing (102) has an aperture formed therein for accessing the interior volume of the heating chamber (108). The heat generator is positioned to extend a fifth distance along the sidewall (114) such that at least a portion of the heat generator is positioned adjacent to at least a portion of the sidewall (114) corresponding to a location of the thermal engagement elements (120). The heat generator is positioned such that the heat generator is not adjacent to any portion of the sidewall (114) corresponding to a location of the gripping elements (122).

20. The heating chamber (108) of claim 1, further comprising a base (112) at a second end of the sidewall (114) opposite the first open end (110). The first portion is positioned further from the first open end (110) than the second portion when the substrate carrier (132) is inserted into the heating chamber (108), and wherein the first portion comprises aerosol substrate (134). The thermal engagement elements (120) are arranged to contact a first portion of the substrate carrier (132). The gripping elements (122) are arranged to grip a second portion of the substrate carrier (132). The second portion does not contain aerosol substrate (134).

25. An aerosol generation device (100), comprising: a power supply (126) a heating chamber (108) according to claim 1; a heat generator arranged to provide heat to the heating chamber (108); control circuitry (128) configured to control supply of electrical power from the power supply (126) to the heat generator; and The outer housing (102) has an aperture formed therein for accessing the interior volume of the heating chamber (108).

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