Vapour provision system with protection from surface heating

Abstract

A vapour provision system comprises an outer housing; an inner body inside the outer housing, and in which heat is generated during operation of the vapour provision system; and at least one shape memory alloy component changeable between a first shape in which the outer housing and the inner body are in a first spatial relationship, and a second shape which places the outer housing and the inner body in a second spatial relationship in which at least a part of the outer housing is spaced outwardly from the inner body by a greater distance than in the first spatial relationship, the second shape being assumed when the shape memory material component is heated to a threshold temperature.

Description

[0001] VAPOUR PROVISION SYSTEM WITH PROTECTION FROM SURFACE HEATING Technical Field

[0002] The present disclosure relates to a vapour provision system with protection from surface heating. The vapour provision system may be a heated tobacco vapour provision system.

[0003] Background

[0004] A type of electronic vapour provision system (e-cigarettes and other electronic nicotine delivery systems) is sometimes referred to as a heated tobacco vapour provision system, a tobacco heated product or a heat-not-burn product. These systems generate vapour or aerosol for inhalation by a user by heating a portion of tobacco (in leaf or other form) to a temperature below the combustion temperature of the tobacco in order to drive nicotine-containing vapour off the tobacco. The user inhales through the portion of tobacco in order to create an air flow, and the vapour is entrained in the air flow as it passes through the tobacco portion to form an aerosol which is delivered for inhalation.

[0005] A heated tobacco vapour provision system contains one or more heaters or heating elements configured to heat the tobacco portion. The tobacco portion may be configured as a rod of tobacco material held inside a wrapping paper, optionally also including a filter part, similar to a conventional cigarette. The heater may have an annular shape with a central cavity into which the tobacco rod is inserted. Other designs utilise one or more heating blades which engage inside the tobacco rod when it is inserted into an opening in the system. Hence, the system includes an inner body in which heat is generated, the inner body comprising or including one or more heaters or heating elements. The inner body is encased in an outer housing or shell. A battery is provided within the system to supply electrical power to the heater. The heater may be a relatively large component compared to the overall size of the system, requiring a battery of substantial capacity to sustain the required level of heating. The power supply from the battery to the heater may be puff- activated by an air flow sensor that detects a user inhalation and activates the supply of power in response, or a user may operate a power switch to activate the heater at the time of inhaling.

[0006] If a user uses the vapour provision system intensively, by rapid or repeated strong inhalation, a significant amount of power may be supplied to the heater so that a substantial amount of heat is generated. Heat energy in excess of that taken up by the tobacco portion may transfer outwards towards the outer housing, which may absorb the heat energy and itself become heated. This can occur very rapidly, and the surface temperature of the outer housing may become uncomfortably or even dangerously high for the user holding the system. Overheating of the outer housing may also occur in the event of a malfunction in the supply of electrical power to the heater. Another type of electronic vapour provision system comprises a reservoir of aerosolisable substrate material, often in liquid form, and an atomiser comprising a heater that heats and vaporises the aerosolisable substrate material as it is delivered to the heater from the reservoir. The vapour is collected by a flow of air through the system created by a user inhalation, to form an inhalable aerosol. The heater of an atomiser is typically much smaller than the heater in a heated tobacco vapour provision system, and may be located in an inner body further from the outer housing of the system, so that heat transfer to the outer housing is less common in atomiser-based systems. Nevertheless, intensive puffing, a depletion of liquid at the atomiser and / or an electrical malfunction may cause overheating of the heater to the extent that sufficient heat energy may transfer to the exterior of the system and produce an overheating of the surface of the outer housing.

[0007] Hybrid systems that combine tobacco heating with an atomiser to generate vapour to supplement the tobacco-originating vapour with flavours or other additives are also known.

[0008] A layer of thermal insulation might be provided within an electronic vapour provision system, on the inner side of the outer housing, for example. This can interrupt the transfer of heat from the inner body to the outer housing so that the exterior of the system remains cool. However, an insulating layer can add to the overall size of the system, and increase manufacturing complexity and costs.

[0009] Accordingly, alternative approaches to protecting vapour provision systems from surface heating are of interest.

[0010] Summary

[0011] According to a first aspect of some embodiments described herein, there is provided a vapour provision system comprising: an outer housing; an inner body inside the outer housing, and in which heat is generated during operation of the vapour provision system; and at least one shape memory alloy component changeable between a first shape in which the outer housing and the inner body are in a first spatial relationship, and a second shape which places the outer housing and the inner body in a second spatial relationship in which at least a part of the outer housing is spaced outwardly from the inner body by a greater distance than in the first spatial relationship, the second shape being assumed when the shape memory material component is heated to a threshold temperature.

[0012] These and further aspects of the certain embodiments are set out in the appended independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with each other and features of the independent claims in combinations other than those explicitly set out in the claims. Furthermore, the approach described herein is not restricted to specific embodiments such as set out below, but includes and contemplates any appropriate combinations of features presented herein. For example, a vapour provision system may be provided in accordance with approaches described herein which includes any one or more of the various features described below as appropriate.

[0013] Brief Description of the Drawings

[0014] Various embodiments of the invention will now be described in detail by way of example only with reference to the following drawings in which:

[0015] Figure 1 shows a simplified schematic longitudinal cross-section through an example heated tobacco vapour provision system to which aspects of the disclosure can be applied;

[0016] Figure 2 shows a simplified schematic longitudinal cross-section through an example atomiser-based vapour provision system to which aspects of the disclosure can be applied;

[0017] Figure 3 shows a temperature scale indicating a temperature regime suitable for implementation in examples of vapour provision systems according to the present disclosure;

[0018] Figure 4A shows a simplified schematic transverse cross-sectional view of a first example vapour provision system according to an aspect of the present disclosure, in a first spatial relationship;

[0019] Figure 4B shows the vapour provision system of Figure 4A arranged in a second spatial relationship;

[0020] Figure 5A shows a simplified schematic transverse cross-sectional view of a second example vapour provision system according to an aspect of the present disclosure, in a first spatial relationship;

[0021] Figure 5B shows the vapour provision system of Figure 5A arranged in a second spatial relationship;

[0022] Figure 6 shows a simplified schematic transverse cross-sectional view of a third example vapour provision system according to an aspect of the present disclosure; and

[0023] Figures 7A-7D show simplified schematic side views of various examples of shape memory alloy components suitable for use in vapour provision systems such as those of the first to third examples, in first and second shapes.

[0024] Detailed Description

[0025] Aspects and features of certain examples and embodiments are discussed I described herein. Some aspects and features of certain examples and embodiments may be implemented conventionally and these are not discussed I described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus discussed herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features.

[0026] As described above, the present disclosure relates to electronic aerosol or vapour provision systems, such as e-cigarettes. Throughout the following description the terms “e- cigarette” and “electronic cigarette” may sometimes be used; however, it will be appreciated these terms may be used interchangeably with aerosol (vapour) provision system or device. Some of these systems are intended to generate an inhalable aerosol by vaporisation of an aerosol-forming substrate in the form of a liquid or gel which may or may not contain nicotine. Other systems are intended to generate an inhalable aerosol by heating (but not burning) a solid substrate to form a vapour. The solid substrate may be for example tobacco or other non-tobacco products, which may or may not contain nicotine. Additionally, hybrid systems which heat both a liquid or gel substrate and a solid substrate are known. The term “aerosolisable substrate material” as used herein is intended to refer to substrate materials which can form an aerosol. In the current context, the aerosol is formed by the application of heat to the substrate, but other means of aerosol formation may be used. The term “aerosol” may be used interchangeably with “vapour”.

[0027] As used herein, the term “component” is used to refer to a part, section, unit, module, assembly or similar of an electronic cigarette or similar device that incorporates several smaller parts or elements, possibly within an exterior housing or wall. An electronic cigarette may be formed or built from one or more such components, and the components may be removably or separably connectable to one another, or may be permanently joined together during manufacture to define the whole electronic cigarette. The present disclosure is applicable to (but not limited to) systems comprising two components separably connectable to one another and configured, for example, as an aerosolisable substrate material carrying component holding liquid or another aerosolisable substrate material (a cartridge, cartomiser or consumable), and a control unit or device component having a battery for providing electrical power to operate an element for generating vapour from the substrate material. For the sake of providing a concrete example, in the present disclosure, a cartridge or cartomiser is described as an example of the aerosolisable substrate material carrying portion or component, but the disclosure is not limited in this regard and is applicable to any configuration of aerosolisable substrate material carrying portion or component. Also, such a component may include more or fewer parts than those included in the examples.

[0028] The present disclosure relates to vapour provision systems that generate heat. In particular it is relevant to vapour provision systems that generate vapour by heating a portion of a solid aerosolisable substrate material, such as tobacco, but it also has relevance to vapour provision systems and components thereof that utilise aerosolisable substrate material in the form of a liquid or a gel which is held in a reservoir, tank, container or other receptacle comprised in the system, and delivered to an atomiser for vaporisation. The terms “liquid”, “gel”, “fluid”, “source liquid”, “source gel”, “source fluid” and the like may be used interchangeably with “aerosolisable substrate material” and “substrate material” to refer to aerosolisable substrate material that has a form capable of being stored and delivered in accordance with examples of the present disclosure. Figure 1 is a highly schematic diagram (not a scale) of a generic example aerosol / vapour provision system of the “heat-not-burn” or “tobacco-heated product” (THP) type, presented for the purpose of showing the relationship between the various parts of a typical system and explaining the general principles of operation. The vapour provision system 10 can be described as having two components, which for ease of comparison with atomiser-based vapour provision systems such as that described below with reference to Figure 2 can be understood as being a control or power component, section or unit 20, and a cartridge component or unit 30 that operates as a vapour generating component. The power component 20 and the cartridge component 30 may be permanently joined together to form a unitary vapour provision system, or may be separably connectable. The division between the components 20, 30 is indicated by the dotted line. In this depiction, the power component 20 and the cartridge component 30 are disposed side-by-side, which is a common arrangement for THP systems, but may alternatively be arranged end-to-end to give a more elongated system.

[0029] The cartridge component 30 is the part of the vapour provision system 10 in which vapour is produced, by heating, so that heat is generated in this part. The cartridge component 30 comprises a deep and narrow opening or cavity 11 extending from one end of the cartridge component 30 (which is use is the top or mouth end) into the interior of the cartridge component 30. The cavity 11 is shaped to receive, and closely hold, part of a tobacco stick or tobacco cartridge 12, which can be inserted into the cavity 11 so that only an end part of the tobacco stick 12 protrudes from the cartridge component 11. The protruding end part of the tobacco stick is placed in a user’s mouth for aerosol inhalation, and may include a filter 12b. The opposite end of the tobacco stick 12, inserted into the cavity 11 and occupying the greater part of the length of the tobacco stick 12, contains a portion of tobacco material 12a, as leaf tobacco or in some other format, held in an outer layer such as a paper wrapper. The tobacco portion 12 provides a solid aerosolisable substrate material for the vapour provision system. Materials other than or in addition to tobacco may be used as a solid aerosolisable substrate material. For convenience the term “tobacco” is used herein to refer to both tobacco and non-tobacco solid substrate materials and “solid” indicates that the substrate material is not a liquid or a gel.

[0030] The cavity 11 has an associated annular electrical heater or heating element or heating elements 4 which surrounds the cavity 11 and therefore also the tobacco portion 12a of an inserted tobacco stick 12. The heater 4 may itself form or define all or part of the side wall of the cavity 11, or may be disposed outwardly of the side wall of the cavity 11. For example, the heater 4 may comprise a tube of metal or other electrically conductive material, or a coil of metal or other electrically conductive material. The heater 4 may operate by ohmic / resistive (Joule) heating, and comprises electrical connections (not shown) so that an electrical current may be passed through it, the electrical resistance of the material of the heater generating heat when current is passed. Alternatively, and as shown in the depicted example, the heater 4 may operate by induction heating. In this arrangement, the heater 4 acts a susceptor, and one or more induction heating coils 7 are arranged around the outside of the heater 4. In induction heating, the induction coil 7 operates as an electromagnet when a high-frequency alternating current is passed through it to produce a magnetic field. The heater 4, being inside the induction coil 7, is a conducting item within the flux of the magnetic field, such that the magnetic field penetrates the heater 4 and induces eddy currents. The eddy currents flow in the heater 4, and generate heat via Joule heating. Operation of the heater exposes the tobacco portion 12a to heat from its outside, and causes heating of the tobacco material so that vapour is produced. In other alternatives (not shown), the heater 4 may comprise one or more heater blades mounted inside the cavity 11, which penetrate into the tobacco portion 12a when the tobacco stick 12 is inserted into the cavity 11. The heater blade(s) may be heated resistively or inductively, and deliver heat energy to the tobacco portion 12a from its inside.

[0031] Other arrangements of one or more heaters suitable for heating the tobacco portion of an inserted tobacco stick will be apparent to the skilled person. The present disclosure is not limited in this way, and is intended to cover any and all such heater arrangements.

[0032] In order to enable inhalation of the vapour / aerosol generated from the tobacco material, the cartridge component 30 includes one or more air inlets 26 in the external wall of the cartridge component 30 (or elsewhere on the vapour provision system 10). The air inlet 26 is in airflow communication with the cavity 11 via an air flow channel or air flow pathway 27. Hence, when a user inhales on the protruding end of an inserted tobacco stick, a flow of air is created through the cartridge component by air A which drawn into the air inlet 26, along the air flow channel 27 to the cavity 11 and into the tobacco stick 12. The air passes through the heated tobacco portion 12a to collect vapour and form an aerosol, and then carries the aerosol through the filter 12b for delivery to the user for inhalation.

[0033] The power component 20 (otherwise, control unit or, simply, device or device component) includes a cell or battery 5 (referred to hereinafter as a battery, and which may be re-chargeable) to provide power for the heater 4 (the associated induction coil being the powered part in inductively heated designs) and other electrical components of the vapour provision system 10. Additionally, there is a controller 28 such as a printed circuit board and / or other electronics or circuitry for generally controlling the vapour provision system 10. The control electronics / circuitry 28 operates the heater 4 using power from the battery 5 when vapour is required, for example in response to a signal from an air pressure sensor or air flow sensor (not shown) that detects an inhalation on the vapour provision system 10 during which air A enters through the one or more air inlets 26. The various parts, elements or components of the vapour provision system 10 are contained within an outer wall of the vapour provision system 10, which may be in two or more parts, such as if the cartridge component 30 and the power component 20 are separably connectable. The outer wall can be considered to comprise an outer housing 15 which may be all or part of the outer wall, and which provides an exterior surface of the vapour provision system 10. The outer housing 15 may comprise one or more layers, possibly formed from different materials.

[0034] In particular, the outer housing 15 is considered, in the context of the present disclosure, to overlay the region of the vapour provision system 10 in which heat is generated. This region will be the interior part or parts of the vapour provision system 10 including, containing or comprising the heater. The region can be defined as an inner body, which is inside the outer housing, and in which heat is generated during operation of the vapour provision system to provide aerosol.

[0035] Figure 2 is a highly schematic diagram (not to scale) of a generic example aerosol / vapour provision system or e-cigarette I electronic cigarette of the atomiser type in which liquid or gel aerosolisable substrate material is vaporised. Again, this is presented for the purpose of showing the relationship between the various parts of a typical system and explaining the general principles of operation. The e-cigarette 10 has a generally elongate shape in this example, extending along a longitudinal axis indicated by a dashed line, and comprises two main components, namely a control or power component, section or unit 20, and a cartridge component, assembly or section 30 (sometimes referred to as a cartomiser or clearomiser) carrying aerosolisable substrate material and operating as a vapourgenerating component.

[0036] The cartomiser 30 includes a reservoir 3 containing a source liquid or other aerosolisable substrate material comprising a formulation such as liquid or gel from which an aerosol is to be generated, for example containing nicotine. As an example, the source liquid may comprise around 1 to 3% nicotine and 50% glycerol, with the remainder comprising roughly equal measures of water and propylene glycol, and possibly also comprising other components, such as flavourings. Nicotine-free source liquid may also be used, such as to deliver flavouring. In a hybrid system, a solid substrate (not illustrated), such as a portion of tobacco or other flavour element through which vapour generated from the liquid is passed, may also be included. The reservoir 3 has the form of a storage tank, being a container or receptacle in which source liquid can be stored such that the liquid is free to move and flow within the confines of the tank. For a consumable cartomiser, the reservoir 3 may be sealed after filling during manufacture so as to be disposable after the source liquid is consumed, otherwise, it may have an inlet port or other opening through which new source liquid can be added by the user. The cartomiser 30 also comprises an electrically powered heating element or heater 4 located externally of the reservoir tank 3 for generating the aerosol by vaporisation of the source liquid by heating. A liquid transfer or delivery arrangement (liquid transport element) such as a wick or other porous element or member 6 is provided to deliver source liquid from the reservoir 3 to the heater 4. A wick 6 may have one or more parts located inside the reservoir 3, or otherwise be in fluid communication with the liquid in the reservoir 3, so as to be able to absorb source liquid and transfer it by wicking or capillary action to other parts of the wick 6 that are adjacent or in contact with the heater 4. This liquid is thereby heated and vaporised, to be replaced by new source liquid from the reservoir for transfer to the heater 4 by the wick 6. The wick may be thought of as a bridge, path or conduit between the reservoir 3 and the heater 4 that delivers or transfers liquid from the reservoir to the heater. Terms including conduit, liquid conduit, liquid transfer path, liquid delivery path, liquid transfer mechanism or element, and liquid delivery mechanism or element may also be used to in this context.

[0037] A heater and wick (or similar) combination is referred to herein as an atomiser or atomiser assembly, and the reservoir with its source liquid plus the atomiser may be collectively referred to as an aerosol source. Other terminology may include a liquid delivery assembly or a liquid transfer assembly, where in the present context these terms may be used interchangeably to refer to a vapour-generating element (vapour generator) plus a wicking or similar component or structure (porous member) that delivers or transfers liquid obtained from a reservoir to the vapour generator for vapour I aerosol generation. Various designs are possible, in which the parts may be differently arranged compared with the highly schematic representation of Figure 2. The heater and wick may be separate parts, of a single part configured for both wicking and heating may be used, such as a component which is both porous and electrically conductive, for example a mesh or grill of metal fibres or wires or a porous conductive ceramic material. In general, an atomiser can be considered as one or more elements that implement the functionality of a vapour-generating or vaporising element able to generate vapour from source liquid delivered to it, and a liquid transport or delivery element able to deliver or transport liquid from a reservoir or similar liquid store to the vapour generator by a wicking action I capillary force. In the present context the atomiser operates by heating the aerosolisable substrate material to generate the vapour, so that the vapour generating element may be an electrical heating element (heater) that operates by ohmic / resistive (Joule) heating or by inductive heating. An atomiser is typically but not essentially housed in a cartomiser component of a vapour generating system. Embodiments of the disclosure are applicable to all and any such configurations which are consistent with the examples and description herein. The cartomiser 30 also includes a mouthpiece or mouthpiece portion 35 having an opening or aerosol outlet through which a user may inhale the aerosol generated by the atomiser 4.

[0038] The power component or control unit or, simply, device or device component 20 includes a cell or battery 5 (referred to herein after as a battery, and which may be rechargeable) to provide power for electrical components of the e-cigarette 10, in particular to operate the heater 4. Additionally, there is a controller 28 such as a printed circuit board and / or other electronics or circuitry for generally controlling the e-cigarette. The control electronics / circuitry 28 operates the heater 4 using power from the battery 5 when vapour is required, for example in response to a signal from an air pressure sensor or air flow sensor (not shown) that detects an inhalation on the system 10 during which air A enters through one or more air inlets 26 in the wall of the control unit 20. When the heating element 4 is operated, the heating element 4 vaporises source liquid delivered from the reservoir 3 by the liquid delivery element 6 to generate the aerosol, and this is then inhaled by a user through the opening in the mouthpiece 35. The aerosol is carried from the aerosol source to the mouthpiece 35 along one or more air flow channels (not shown) that connect the air inlet(s) 26 to the aerosol source to the aerosol outlet when a user inhales on the mouthpiece 35. In other designs, air inlets may be located in the outer wall of the cartomiser 30 so that air enters directly into the cartomiser 30 instead of arriving there via the power component 20.

[0039] The power component (control unit) 20 and the cartomiser (cartridge assembly) 30 are, in this example, separate connectable parts detachable from one another by separation in a direction parallel to the longitudinal axis, as indicated by the solid arrows in Figure 2. The components 20, 30 are joined together when the device 10 is in use by cooperating engagement elements 21, 31 (for example, a screw or bayonet fitting) which provide mechanical and in some cases electrical connectivity between the power section 20 and the cartridge assembly 30. Electrical connectivity is required if the heater 4 operates by ohmic heating, so that current can be passed through the heater 4 when it is connected to the battery 5. In systems that use inductive heating, electrical connectivity can be omitted if no parts requiring electrical power are located in the cartomiser 30. An inductive work coil can be housed in the power section 20 and supplied with power from the battery 5, and the cartomiser 30 and the power section 20 shaped so that when they are connected, there is an appropriate exposure of the heater 4 to flux generated by the coil for the purpose of generating current flow in the material of the heater. The Figure 2 design is merely an example arrangement, and the various parts and features may be differently distributed between the power component 20 and the cartridge assembly section 30, and other components and elements may be included. The two sections may connect together end-to- end in a longitudinal configuration as in Figure 2, or in a different configuration such as a parallel, side-by-side arrangement. The system may or may not be generally cylindrical and / or have a generally longitudinal shape. Either or both sections or components may be intended to be disposed of and replaced when exhausted (the reservoir is empty or the battery is flat, for example), or be intended for multiple uses enabled by actions such as refilling the reservoir and recharging the battery. In other examples, the system 10 may be unitary, in that the parts of the control unit 20 and the cartomiser 30 are comprised in a single housing and cannot be separated. Embodiments and examples of the present disclosure are applicable to any of these configurations and other configurations of which the skilled person will be aware.

[0040] The various parts, elements or components of the e-cigarette 10 of Figure 2 are contained within an outer wall of the e-cigarette 10, which may be in two or more parts if the cartridge component 30 and the power component 20 are separably connectable. The outer wall can be considered to comprise an outer housing 15 which may be all or part of the outer wall, and which provides an exterior surface of the vapour provision system 10. The outer housing 15 may comprise one or more layers, possibly formed from different materials. In particular, the outer housing 15 is considered, in the context of the present disclosure, to overlay the region of the e-cigarette 10 in which heat is generated. This region will be the interior part or parts of the e-cigarette 10 including, containing or comprising the heater. The region can be defined as an inner body, which is inside the outer housing 15, and in which heat is generated during operation of the vapour provision system to provide aerosol.

[0041] Returning to heated tobacco vapour provision systems such as the Figure 1 example, the heater is typically a relative large item within the system as a whole, with a corresponding capacity for electric power supply required of the battery. If a user inhales (puffs) intensively on the system, a significant amount of power may be supplied to the heater, with a corresponding amount of heat being generated. This may exceed the amount of heat able to be absorbed by tobacco portion, and the excess heat may propagate outwardly from the inner body of the system where the heat in generated, and reach the outer housing, which can become heated. The temperature of the external surface of the system may quickly become uncomfortably or dangerously high for the user holding the system. A malfunction of the supply of electrical power to the heater may similarly cause undesirable overheating of the outer housing. This may also arise in atomiser-based vapour provision system and hybrid vapour provision systems.

[0042] The present disclosure proposes to address this by including at least one shape memory alloy (SMA) component in the vapour provision system. The SMA component is formed from a shape memory alloy configured to change its shape from a first shape when the SMA component is a first, lower temperature to a second shape when the SMA component is heated to a second, higher temperature. The SMA component is arranged such that the shape change implemented by an increase to the higher temperature (which can be designated as a threshold temperature) causes a rearrangement of the spatial configuration of the vapour provision system. At the lower temperature the first shape of the SMA component maintains the inner body and the outer housing in a first spatial relationship, and the change to the second shape when the SMA component reaches the threshold temperature places the inner body and the outer housing into a second spatial relationship in which at least part of the outer housing is spaced outwardly from the inner body by a greater distance than in the first spatial relationship. The first spatial relationship can be considered as an operational spatial configuration of the vapour provision system maintained when the heater is cool or is heated to its usual operating temperature (or within an operating temperature range) for vaporising aerosolisable substrate material, and in which the outer housing overlays the inner body with little or no spacing according to the intended outer appearance or design of the vapour provision system. The second spatial relationship includes a spacing or an increased spacing between the inner body and the outer housing in order that the outer housing is placed at a greater distance from heat generated in the inner body, and as such is less exposed to this heat and avoids overheating in the event that excess heat radiates from the inner body. The increased gap provides greater thermal insulation around the inner body, to reduce heat transfer to the outer housing. The risk of discomfort or harm to the user holding the vapour provision system is reduced or avoided, because the external surface of the vapour provision system preserves a lower temperature. The threshold temperature is preferably above a typical external temperature of a vapour provision system operating normally and as intended for vapour generation, so that the first spatial relationship is maintained during normal operation and use of the vapour provision system. The threshold temperature is preferably below a temperature considered to be uncomfortable for handling a vapour provision system. If excess heat is generated in the inner body during operation of the vapour provision system, such as by intensive puffing, some of the excess heat is transferred to the SMA component. The SMA component increases in temperature, and when the threshold temperature is reaches the SMA component transforms to the second shape. This causes a relative movement between the inner body and the outer housing which increases their spacing or separation from one another and prevents or inhibits the transfer of heat energy from the inner body to the outer housing. Hence, if the heater becomes overheated, above its intended operating temperature, the second spatial relationship is adopted before the vapour provision system becomes uncomfortably hot to hold, and the user is protected. The outer housing is removed from further heat exposure or placed at a position of reduced heat exposure, does not become overheated, and can maintain a safe handling temperature. In effect, the outer housing is “popped” outwardly away from the inner body in the event that the amount of heat produced in the inner body threatens to increase the external surface temperature of the vapour provision system above a comfortable or safe level for the user.

[0043] The proposed use of SMA to protect the outer housing from excess heat exposure uses an effectively automatic process that converts thermal energy, produced directly during operation of the heater, into mechanical energy used to separate the outer housing from the inner body if the risk of external overheating becomes high.

[0044] Depending on the design of the vapour provision system and the form of the outer housing, together with the arrangement of the one or more SMA components, all of the outer housing may be moved outwardly by the change to the second shape of the SMA components. This is not necessary, however, and the vapour provision system may be configured so that only a part of the outer housing is placed at an increased spacing from the inner body. For example, the outer housing around the side walls of the vapour provision system may be moved outwardly, so that the outer housing around the full perimeter of the vapour provision system “pops” out if overheating occurs. This may give a comfortable effect for the user holding the system since the change will be symmetrically distributed around the system. In more limited arrangements, only that part of the outer housing that overlays the inner body is placed at an increased separation from the inner body. Alternatively, only a part of that part of the outer housing that overlays the inner body is placed at an increased separation, for example, a part or parts closer to the heater within the inner body which are most vulnerable to becoming too hot.

[0045] Shape memory alloys are metal-containing alloy materials that can exist in two different phases, arising from three different crystal structures: twinned martensite, detwinned martensite, and austenite. For the purposes of the present disclosure, these can be considered as two crystal structures: martensite and austenite. The shape-memory properties arise from thermo-mechanical behaviour governed by a phase transformation between the martensite and austenite crystal structures. The crystals are oriented differently in the two crystal structures, causing different external shapes of the material. A transformation between the crystal structures can be achieved by applied stress (mechanical load) or a change in temperature. Accordingly, a temperature change across a relevant temperature boundary or threshold applied to a shape memory alloy component causes the component to change between a shape adopted with the martensite crystal structure and a shape adopted with the austenite crystal structure. The transformation is not timedependent, so the material is considered to have a “shape memory”, retaining one shape under a constant temperature above or below the temperature boundary, and attaining a different shape when its temperature crosses the boundary.

[0046] For the presently proposed application, a shape memory component is configured to have a first shape, corresponding to the martensite crystal structure, at or below a first, lower temperature (the martensite temperature, Mt), and a second shape, corresponding to the austenite crystal structure, at or above a second, higher temperature (the austenite temperature, At). Since these temperatures vary according to the type of SMA (the metals in the alloy) the component is formed from an SMA for which the boundary between the first temperature and the second temperature corresponds to a temperature above a selected acceptable outer temperature of the vapour provision system during normal use. During normal operation, the SMA component will be at or below the martensite temperature, and in its first shape. The SMA component is configured, and associated the inner body and the outer housing such that the first shape maintains the inner body and the outer housing in the first spatial relationship during normal operation for vapour generation, and when the vapour provision system is not being used. When a situation occurs that causes excessive heat generation in the inner body, the overheating produces a temperature rise in the associated SMA component, the SMA component heats above the martensite temperature and begins to adopt its second shape, which is attained with the temperature reaches the austenite temperature, and the SMA component is transformed to the second shape. This changes the spatial configuration of vapour provision system to the second spatial relationship, and the separation of inner body and the outer housing is increased compared to the first spatial relationship, such that the outer housing is now spaced outwardly from the inner body by a greater distance that in the first spatial relationship. The outer housing is thereby more remote from source of heat energy in the inner body and any increase in temperature of the outer housing is prevented or reduced.

[0047] To achieve this, the SMA component can be configured such that the change from the first shape to the second shape causes an increase in at least one external dimension of the SMA component. This increase is employed such that the SMA component acts on or within one or both of the outer housing and the inner body to move one or both of the outer housing and the inner body away from the other, by situating the SMA component within the vapour provision device in association with the outer housing and the inner body such that the change of shape produces the required movement.

[0048] A shape memory alloy may be a two-way effect shape memory alloy, or a one-way effect shape memory alloy. A two-way effect shape memory alloy is considered most useful to implement the currently proposed concept. A two-way effect shape memory alloy is a SMA in which the shape change between the first shape and the second shape occurs in both directions. The shape change is reversible under heating and cooling. When the SMA component is below the martensite temperature, it maintains its first shape. Above the martensite temperature the SMA component begins to change towards the second shape, and the second shape is assumed when the SMA component reaches the austenite temperature. Above the austenite temperature the second shape is maintained. If the SMA component cools below the austenite temperature, it begins to change back to the first shape, and when the martensite temperature is reached, the first shape is assumed. Note that the change of shape during heating from the martensite temperature and the austenite temperature is at a different rate from the change of shape during cooling from the austenite temperature to the martensite temperature. The rates of change effectively follow a hysteresis-like loop.

[0049] In the context of the present disclosure, a SMA component formed from two-way effect shape memory alloy enables a vapour provision system to resume its original spatial configuration after excess heat generation in the inner body has occurred. The excess heat energy heats the SMA component, which adopts its second shape and places the outer housing and the inner body into the second spatial relationship, with an increased spacing, to keep the outer housing at a manageable temperature. Later, as the inner body ceases excess heat generation (after the power supply to the heating element has been interrupted, or the user’s puffing rate decreases or puffing stops, for example), the SMA component cools and resumes its first shape, placing the outer housing and the inner body back into their first spatial relationship. The vapour provision system resumes its original configuration, and any change in its outer appearance, shape or size causes by the second spatial relationship is reversed. The vapour provision system can be protected from surface heating repeatedly over its lifetime.

[0050] In contrast, a one-way effect shape memory alloy is a SMA in which the shape change from the first shape to the second shape occurs in one direction only, and is not reversible under subsequent temperature changes. As with a two-way effect SMA, the SMA component maintains its first shape when below the martensite temperature, and begins to change towards the second shape when the martensite temperature is exceeded. The SMA component assumes its second shape when the austenite temperature is reached. The second shape is maintained above the austenite temperature, but is also maintained when the SMA component cools below the austenite temperature. There is no return to the first shape even below the martensite temperature. In the context of the present disclosure, therefore, a vapour provision system will not assume its original configuration when the SMA component cools after experiencing heating. The outer body will remain separated from the inner body by a greater distance during future use of the vapour provision system. This larger spacing will inherently help to protect the outer housing from temperature rises, but the original appearance of the vapour provision may be lost. Accordingly, one-way effect SMAs may be less preferable in the current context.

[0051] Figure 3 shows a schematic representation of a suitable temperature regime for implementing a vapour provision system according to an example of the disclosure. A temperature scale for the temperature T of the external surface of a vapour provision system is indicated. At the lower end of the scale, there is an operating temperature range ATo. This is a range of temperatures that the outer housing may reach during normal operation of the vapour provision system. The vapour provision system is designed so that during normal operation, the outer housing will maintain a surface temperature that is within a range of temperatures that the user is expected to find comfortable to hold. For example, there may be various parts interposed between the heater (which will typically operate at a temperature between about 250°C and 300°C) and the outer housing that keep the outer housing very much cooler than the heater. There may be insulation layers, air gaps, and other components that occupy the space between the heater and the outer housing, for example. Also, the outer housing may be made from a material that aids in this temperature limitation. For example, the outer housing may formed wholly or partly from silicone. A slim outer profile or shape of the vapour provision system may be attractive and desirable, however, so that there is less space available for thermal protection between the heater and the outer housing. This can make the external temperature more likely to exceed comfortable limits if the heater temperature increases. As an example, a typical range of temperatures of the outer housing during normal operation of the vapour provision system may be 25°C to 35°C. The use of SMA components as described herein can help to protect the user from high surface temperatures while allowing a slim and compact device.

[0052] When the vapour provision system is working within the intended operating temperature range of the heater, or when the vapour provision system is not operational and the heating element is cool or cooling from the operating temperature, the at least one SMA component will be in its first shape. The martensite temperature Mt is at (in this example) or slightly above (more generally) the external surface temperature at the top of the defined operating temperature range ATo, when the SMA component will begin to transform or change shape to the second shape. Hence, the SMA component begins to change shape if the heating element begins to overheat above its maximum intended operating temperature. This produces excess heat which can radiate out from the inner body and cause a temperature increase of the SMA component. The shape change of the SMA component continues as the temperature increases until the austenite temperature At is reached, at which the SMA assumes its second shape. The outer housing and the inner body are now separated by a distance sufficient to protect the outer housing from an excessive temperature increase causes by exposure to the excess heat from the inner body. The increased spacing offers protection over a protected temperature range ATp in which the heater continues to generate excess heat that would otherwise cause the outer surface of the vapour provision system to become uncomfortably or dangerously hot, in the absence of the SMA components. The protected temperature range extends upwardly from the austenite temperature, and may include temperatures such as 48°C or 50°C, at which the outer housing would be too hot to hold. The outer housing is saved from reaching these high temperatures by the SMA component separating it from the inner housing, however. When a two-way effect shape metal alloy is used for the SMA component, the process is reversed when the inner body and hence the SMA component begin to cool, and the SMA component starts to change back to the first shape when it reaches the austenite temperature.

[0053] The austenite temperature At can be defined as the threshold temperature at which the SMA component assumes its second shape. The alloy used for the SMA component may be selected such that the austenite temperature corresponds to a temperature at which the outer housing may begin to increase in temperature above what is considered to be a safe and comfortable maximum acceptable outer temperature for the vapour provision system, if not separated from the inner body. Purely as an example, this temperature might be at or around 48°C, so the threshold temperature can be chosen to be not higher than 48°C. Accordingly, the SMA component will have fully assumed the second shape and placed the outer body in a position of reduced risk of high temperature as the maximum acceptable temperature is reached. A margin may be introduced by having the austenite temperature below the maximum acceptable temperature, for example at about 45°C. If, as noted above, the external temperature of the vapour provision device is designed to be in the range of 25°C - 35°C during normal operation, the threshold temperature may therefore, in some examples be in the range of 35°C to 45°C, although threshold temperatures outside this range are not excluded, and will be apparent to the skilled person according to the design of the vapour provision system. The aim is that the threshold temperature at which the SMA component assumes the second shape is a temperature above which it is desired to protect the user from an external temperature of the vapour provision system that the user may perceive as being too hot to comfortably hold. In general, the threshold temperature is selected to cause the SMA shape change to occur between the outer housing lying at a comfortable temperature for use of the vapour provision system, and the outer housing reaching a temperature which is not comfortable for the user.

[0054] The shape transformation is not an instantaneous effect; rather there is a temperature range between the martensite temperature Mt (below which the SMA component has the first shape) and the austenite temperature At (above which the SMA component has the second shape) during which the shape change occurs. This is indicated by the hashed region in Figure 3.

[0055] A large variety of shape memory alloys are known, with a range of properties. In particular, properties that can vary between different SMAs are the value of the martensite temperature and the value of the austenite temperature. An SMA for the shape memory alloy component should therefore be selected with reference to the intended external surface temperature of the vapour provision system during normal operation, and the perceived maximum acceptable surface temperature. The choice of SMA should be such that the shape change from the first shape to the second shape begins at a temperature at the upper end of the intended range of normal external surface temperature, so that the first spatial relationship between the inner body and the outer housing, and hence the intended external shape and appearance of the vapour provision system, are maintained during normal operating conditions. However, excessive heat accumulation can occur quickly, particularly in a heated tobacco vapour provision system, so it is preferable that the shape change is completed (the second spatial relationship is in place) over a small temperature range. Hence, the martensite temperature is preferably at or only slightly above the maximum intended external temperature of vapour provision system under normal operation, and the austenite temperature is preferably not substantially higher than the martensite temperature. For example, an SMA is which the martensite temperature and the austenite temperature are separated by not more than 5°C, or not more than 7.5°C, or not more than 10°C could be used.

[0056] Examples of suitable shape memory alloys include CuZnAI (two-way effect SMA), NiTi (two-way effect SMA) and NiAl (one-way effect SMA). Other SMAs are not excluded and may be used as preferred. The alloy formula of an SMA can be modified, and a component made from the SMA can be trained in order to achieve shape transformation at the required temperature or in the required temperature range, as will be understood by the skilled person.

[0057] Figure 4A shows a highly schematic transverse cross-sectional view of an example vapour provision system according to the present disclosure. The vapour provision system 10 is a heated tobacco vapour provision system such as the example in Figure 1. It therefore comprises, with cartridge and power components which may or may not be separable, a battery 5, a cavity 11 for receiving a tobacco stick (not shown), and a heater 4 which in this example is arranged to surround the cavity for heating a tobacco portion of a tobacco stick received in the cavity 22. The internal structure of the vapour provision system defines an inner body 16 in which the heater 4 is located, and in which heat is therefore generated during operation of the vapour provision system. An outer housing 15 is disposed around the inner body 16. The outer housing 15 may comprise one or more layers (not shown). It may define a shell or receptacle in which the internal components of the vapour provision system 10 are arranged, or it may be merely an outer shell or skin that provides an external surface of a desired visual effect, tactile feel, and generally desired appearance. There is a small space 19 between the outer surface of the inner body 16 and the inner surface of the outer housing 15. The space 19 may be an air gap to provide an insulating effect to limit the transfer of heat from the inner body 16 to the outer housing. Alternatively, the space 19 might be filled with an insulating material. A plurality (in this example, four) of SMA components 18 are arranged in the space 19. The SMA components 18 are configured and arranged such that in their second shape they have an increased dimension along the direction of the width of the space 19, in other words, along the direction between the inner body 16 and the outer housing 15. The SMA components 18 are spaced apart at intervals around the perimeter of the inner body 16. They may be mounted on the outer surface of the inner body 16, on the inner surface of the outer housing 15, or both. Preferably the SMA components 18 are in contact with the inner body for the purposes of heat conduction, but this is not essential, and the SMA components may be heated by exposure to the air or material in the space 19 when that is heated by the inner body 16. In Figure 4A, the vapour provision system 10 is shown in a normal operating condition in which the heater 4 is generating only an intended amount of heat, or a non- operational condition in which the heater 4 is turned off. The SMA components 18 are therefore at a temperature below their threshold temperature, and are in their first shape. The first shape maintains the outer housing 15 and the inner body 16 in their first spatial relationship, giving the intended usual configuration of the vapour provision system.

[0058] Figure 4B shows the example vapour provision system 10 of Figure 4A, again as a highly schematic transverse cross-section, after the heater has generated an excess amount of heat which is transferred to the outer surface of the inner body 16. The SMA components 19 have been heated by this excess heat and have reached their threshold temperature. Hence, the SMA components 19 have changed to their second shape, in which they have an increased dimension across the width of the space 19. The increased dimension exceeds the width of the space in the first spatial relationship, so the SMA components act against the inner surface of the outer housing 15 and move the outer housing outwards. The width of the space 19 increases, and the inner body 16 and the outer housing 15 are placed into their second spatial relationship. The outer housing 15 is now spaced outwardly from the inner body 16 by a greater distance than in the first spatial relationship. The increased spacing or separation decreases the transfer of heat from the inner body 16 to the outer housing 15, and the temperature of the outer housing is prevented from increasing excessively. The external surface temperature of the outer housing can thereby be limited to a safe and comfortable temperature for the user holding the vapour provision system.

[0059] A relatively small spacing between the inner body and the outer housing can be sufficient to limit the exterior temperature increase. For example, in the second spatial relationship, the outer housing may be spaced outwardly from the inner body by a distance in the range of only 1 mm to 2 mm. A small space or gap minimises the change in external shape and appearance of the vapour provision system caused by the temperature protection, so may be more acceptable to the user. However, larger spaces are not excluded, and may be considered more appropriate as providing a higher level of protection. Hence, in the second spatial relationship, the space may have a width up to 5 mm, for example, such as in the range of 1 mm to 5 mm or 2 mm to 5 mm, or 3 mm to 5 mm. Spaces wider than 5mm are not excluded, however.

[0060] The size of the space can also be considered in terms of its increase from the first spatial relationship to the second spatial relationship, rather than the absolute size of the space. A small increase can be sufficient to provide useful thermal protection, and does not significantly disrupt the external appearance and feel of the vapour provision system. Therefore, in the second spatial relationship, the outer housing can be spaced outwardly from the inner body by at least 1 mm more than in the first spatial relationship. In designs such as the Figure 4A design in which there is a space between the inner body and the outer housing, this can be described as that in the first spatial relationship the outer housing is spaced outwardly from the inner body by a first distance and in the second spatial relationship the outer housing is spaced outwardly from the inner body by a second distance greater than the first distance. In some examples, the second distance may be greater than the first distance by at least 1 mm. Smaller separations may still be useful, however, providing some thermal protection while minimising external changes to the vapour provision system, so that in other examples the second distance may be greater than the first distance by at least 0.5 mm.

[0061] The presence of the space between the inner body and the outer housing in the first spatial relationship, as shown in Figure 4A can provide some thermal protection at normal operating temperatures, by interrupting the transfer of heat from the operating heater to the outer housing. However, this is not essential, and in other examples (not shown), the inner surface of the outer housing may be partly or wholly in contact with outer surface of the inner body. In such designs, the SMA components may be accommodated in recesses formed in the outer surface of the inner body or the inner surface of the outer body.

[0062] In the example vapour provision system shown in Figures 4A and 4B, the change of the SMA components to the second shape moves the outer housing outwardly from the inner body, to achieve the second spatial relationship. This can be achieved by forming the outer housing at least partly from a flexible, resilient or elastic material. In this way, the SMA components will push the outer housing in an outward direction, away from the inner body, and the outer housing can distort, deform, stretch or enlarge to move outwards into the second spatial relationship. When the SMA components resume their first shape, the outer housing can contract or undistort to resume its size and shape in the first spatial relationship, restoring the external size and shape of the vapour provision system. As noted above, the outer housing may comprise silicone, but other suitable materials will be apparent to the skilled person, such as but not limited to polycarbonate, polypropylene, thermoplastic elastomers, aluminium, copper and stainless steel. More than one such material may be used to make different parts of the outer housing.

[0063] However, it is envisaged that in other designs, the opposite arrangement may be possible. If the inner body is arranged or configured to be movable within the outer housing, the SMA components may be configured to instead push the inner body away from part of the outer housing to increase the width of the space when they assume their second shape. The inner body is then restored to its original position when the SMA components return to their first shape.

[0064] In order to produce the desired increased spacing between the inner body and the outer housing, the whole of the outer housing need not be spaced outwardly from the inner body. One or more parts of the outer housing only can be spaced outwardly when the second spatial relationship is assumed. For example, a part or parts of the outer housing that overlay the inner body may be spaced further from the inner body, while other parts of the outer housing remain according to the first spatial relationship. The inner body, being the part of the vapour provision system where heat is generated, need not occupy all the room within the outer housing, in which case it may not be necessary to space all of the outer housing outwardly from the inner body. In general, in the second spatial relationship, at least part of the outer housing is spaced outwardly from the inner body further than in the first spatial relationship.

[0065] Figure 5A shows a highly schematic transverse cross-sectional view of another example vapour provision system according to the present disclosure. The vapour provision system 10 is largely the same as the Figure 4A example, except that it comprises only two SMA components 18. The two SMA components 18 are located between the inner body 16 and the outer housing 15 at parts of the inner body where the heater 4 is closer to the surface of the inner body, where heat generation is highest. No SMA components are included around the part of the inner body 16 that contains the battery 5, since no heat is directly generated here. In some interpretations, the inner body 16 may be considered not to include the battery and its environs, and instead to be those internal parts at and around the heater 4 only. In Figure 5A the SMA components 18 have their first shape.

[0066] Figure 5B shows the vapour provision system 10 in its second spatial relationship and the SMA components 18 in their second shape. Because the SMA components 18 are grouped near the heater 4, only the part of the outer housing 15 which overlays the region of the inner body 16 containing the heater 4 is moved outwardly to create the larger space of the second spatial relationship.

[0067] In the preceding examples, the SMA components are arranged between the outer housing and the inner body. Any suitable number of SMA components can be used, in order to produce the desired configuration of separation between the outer housing and the inner body. The separation need not be of a constant width. For example, a larger space may be provided at positions closer to the heater, where heat generation will be greatest. For two or more SMA components, the SMA components may be evenly distributed around the perimeter of the inner body, or may be unevenly distributed, according to the desired shape of the space in the second spatial configuration. The SMA components may be identical to one another, or may be different. For example, the second shape of one or more components may give a larger extended dimension than that of other components, in order to move the outer housing outwardly by a greater distance at the location of that SMA component or those SMA components. This can also tailor the width of the space, for example to make it wider in some places that others. In some examples, a single SMA component may be adequate to produce a space in the second spatial configuration which is sufficient to limit heating of the outer housing to a safe or comfortable temperature. In general, any number, arrangement and position of the SMA components can be used that produces the required increased distance between the inner body and the outer housing when the SMA components change to their second shape.

[0068] As noted above, the concept is not limited to heated tobacco vapour provision systems, and may also be applied to atomiser-based vapour provision systems. Exterior temperature rises are generally less significant in such systems, but the concept may still be applied as a safety measure.

[0069] Figure 6 shows a highly schematic transverse cross-sectional view of a further example vapour provision system according to the present disclosure. In this example, the vapour provision system 10 is an atomiser-based system. The inner body 16 includes an annular reservoir 3. An atomiser comprising a wick 6 surrounded by a coil heater 4 is arranged across the central void of the annular reservoir, with each end of the wick 6 extending into the interior of the reservoir 3 to absorb liquid aerosolisable substrate material. In common with the previous examples, the vapour provision system 10 includes an outer housing 15 enclosing the inner body 16. Four SMA components 18 are arranged around the perimeter of the inner body 16 in a space between the inner body 16 and the outer housing 15, in order to allow the spatial relationship of the inner body 16 and the outer housing 15 to be changed from the depicted first spatial relationship to a second spatial relationship (not shown) in which the outer housing 15 is spaced outwardly from the inner body 16 by a greater distance, as previously described.

[0070] The SMA component or components may be configured with any first shape and second shape that correspond to a suitably sized increase in the dimension of the SMA component along the direction separating the inner body and the outer housing. Dimensional increases in other directions may also occur, depending on the configuration chosen for the SMA components. Some examples will now be described. However, these are in no way limiting, and the skilled person will readily appreciate that other first and second shapes can readily be employed which will produce the required movement of the outer housing and / or the inner body to an increased separation.

[0071] Figure 7A shows a schematic side view of a first example of a suitable SMA component. In this example, the SMA component 18 has the form of a coil or helical spring. In the first shape, the coil spring has its turns wound at a first, smaller, pitch, corresponding to a shorter length or height of the spring S1. When the coil spring is heated it transforms to its second shape, indicated by the arrow. Now, the coil spring has its turns wound at a second, larger, pitch, giving a greater length or height S2 to the spring. Coil springs formed from shape memory alloys are readily available so may be convenient choice of shape for the current proposal.

[0072] In other examples, the SMA component may have a simpler curved or bent format, that increases its dimension in its second shape by decreasing the amount of curvature or bending. The following are some possibilities.

[0073] Figure 7B show a schematic side view of a second example of a suitable SMA component. The SMA component 18 comprises two straight arm portions connected at an angled joint having an angle size 0. In the first shape, the angle 0 is small, so that the arms are close together and the SMA component 18 has a small height S1. When heated, the transformation to the second shape opens up the angled joint to a larger value of 0, so the arms pivot further away from one another, and the SMA component assumes a larger height S2.

[0074] Figure 7C shows a schematic side view of a third example of a suitable SMA component. The SMA component 18 is similar to that of Figure 7B but in this case the two arm portions are curved or arcuate instead of straight, but are again connected at an angled joint of angle size 0. The SMA component 18 therefore has a form similar to a leaf spring. As in the Figure 7B example, in the first shape, the angle 0 is smaller, the arms are close and the height S1 is small. The transformation to the second shape increases the angle 0 of the joint to give a large height S2 for the SMA component 18.

[0075] Figure 7D shows a schematic side view of a fourth example of a suitable SMA component. In this example, the SMA component 18 has the form of a curved bar or rod in its first shape, with a corresponding height S1 given by the separation of its two ends. The change to the second shape, when heated, decreases the curvature of the bar until the bar is straight, now having a correspondingly greater height S2 because the ends of the bar are now separated by the complete length of the rod. Other second shapes in which the bar straightens only partially are further alternatives. While a variety of shapes and configurations of SMA components have been described herein, alternatives which perform the same function will be readily apparent to the skilled person and not excluded.

[0076] In conclusion, in order to address various issues and advance the art, this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and / or exclusive. They are presented only to assist in understanding and to teach the claimed invention(s). It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the claims. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. other than those specifically described herein. The disclosure may include other inventions not presently claimed, but which may be claimed in future.

Claims

Claims1. A vapour provision system comprising: an outer housing; an inner body inside the outer housing, and in which heat is generated during operation of the vapour provision system; and at least one shape memory alloy component changeable between a first shape in which the outer housing and the inner body are in a first spatial relationship, and a second shape which places the outer housing and the inner body in a second spatial relationship in which at least a part of the outer housing is spaced outwardly from the inner body by a greater distance than in the first spatial relationship, the second shape being assumed when the shape memory material component is heated to a threshold temperature.

2. A vapour provision system according to claim 1 , wherein the part of the outer housing is a part of the outer housing overlaying the inner body.

3. A vapour provision system according to claim 1 or claim 2, wherein the threshold temperature is in the range of 35°C to 45°C4. A vapour provision system according to claim 1 or claim 2, wherein the threshold temperature is not higher than 48°C.

5. A vapour provision system according to any preceding claim, wherein the at least one shape memory alloy component is heated during operation of the vapour provision system by heat generated in the inner body.

6. A vapour provision system according to any preceding claim, wherein in the second spatial relationship the part of the outer housing is spaced outwardly from the inner body by a distance in the range of 1 mm to 2 mm.

7. A vapour provision system according to any preceding claim, wherein in the first spatial relationship the part of the outer housing is spaced outwardly from the inner body by a first distance and in the second spatial relationship the part of the outer housing is spaced outwardly from the inner body by a second distance greater than the first distance.

8. A vapour provision system according to claim 7, wherein the second distance is greater than the first distance by at least 1 mm.

9. A vapour provision system according to any preceding claim, wherein the at least one shape memory alloy component is formed from CuZnAI, NiTi or NiAI.

10. A vapour provision system according to any preceding claim, wherein the at least one shape memory alloy component is formed from a two-way effect shape memory alloy configured to resume the first shape from the second shape when the at least one shape memory alloy component cools to a temperature below the threshold temperature.

11. A vapour provision system according to any preceding claim, wherein the change of the at least one shape memory alloy to the second shape moves at the part of the outer housing outwardly away from the inner body.

12. A vapour provision system according to any one of claims 1 to 11 , wherein the at least one shape memory alloy component is arranged between the outer housing and the inner body.

13. A vapour provision system according to claim 12, wherein the at least one shape memory alloy component comprises a plurality of shape memory alloy components arranged between the outer housing and the inner body.

14. A vapour provision system according to claim 12, wherein the plurality of shape memory alloy components are arranged around an outer perimeter of the inner body.

15. A vapour provision system according to any preceding claim, wherein the at least one shape memory alloy component is formed as a spring.

16. A vapour provision system according to claim 15, wherein the at least one shape memory alloy component is formed as a coil spring.

17. A vapour provision system according to claim 15, wherein the at least one shape memory alloy component is formed as a leaf spring.

18. A vapour provision system according to any preceding claim, wherein the outer housing at least partly comprises an elastic material.

19. A vapour provision system according to any preceding claim, wherein the outer housing is at least partly formed from silicone.

20. A vapour provision system according to any preceding claim, wherein the inner body includes at least one heater.

21. A vapour provision system according to claim 20, wherein the heater is configured for heating a portion of tobacco.

22. A vapour provision system according to claim 20, wherein the heater is comprised in an atomiser configured to generate vapour from aerosolisable substrate material delivered to the heater from a reservoir in the vapour provision system.

23. A vapour provision system according to any one of claims 1 to 20, wherein the vapour provision system is a heated tobacco vapour provision system configured to heat a portion of tobacco received in the inner body.

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