A Cartridge for a Vapour Generating Device and a Vapour Generating Device

TECHNICAL FIELD

The present disclosure relates generally to a vapour generating device, such as an electronic cigarette. Embodiments of the present disclosure relate in particular to a cartridge for an electronic cigarette and to an electronic cigarette incorporating the cartridge.

TECHNICAL BACKGROUND

Electronic cigarettes are an alternative to conventional cigarettes. Instead of generating a combustion smoke, they vaporize a liquid which can be inhaled by a user. The liquid typically comprises an aerosol-forming substance, such as glycerine or propylene glycol, that creates the vapour when heated. Other common substances in the liquid are nicotine and various flavourings.

The electronic cigarette is a hand-held inhaler system, typically comprising a mouthpiece section, a liquid store and a power supply unit. Vaporization is achieved by a vaporizer or heater unit which typically comprises a heating element in the form of a heating coil and a fluid transfer element such as a wick. Vaporization occurs when the heater heats the liquid in the wick until the liquid is transformed into vapour.

Conventional cigarette smoke comprises nicotine as well as a multitude of other chemical compounds generated as the products of partial combustion and/or pyrolysis of the plant material. Electronic cigarettes on the other hand deliver primarily an aerosolized version of an initial starting e-liquid composition comprising nicotine and various food safe substances such as propylene glycol and glycerine, etc., but are also efficient in delivering a desired nicotine dose to the user. Electronic cigarettes need to deliver a satisfying amount of vapour for an optimum user experience whilst at the same time maximizing energy efficiency.

WO2017/179043 discloses an electronic cigarette comprising a disposable cartridge and a reusable base part. The cartridge has a simplified structure which is achieved by keeping the main heating element in the re-usable base part, while the cartridge is provided with a heat transfer unit. The heat transfer unit is configured to transfer heat from the heating element to the proximity of liquid in the cartridge to produce a vapour for inhalation by a user.

The establishment and satisfactory maintenance of a thermal contact between the reusable base part that contains the heat source and the fluid transfer medium, such as a ceramic wick in the disposable cartridge, can prove difficult. One manner in which this has been improved is by the provision of a deformable thermal interface membrane between the heater and the porous wick. The membrane is a flexible, thin membrane configured to assist in rapid and even heating of the target in an accurate and defined geometry, reducing the amount of lateral thermal spreading (i.e. thermal losses).

Additionally, dimples have been provided in the heat transfer unit which serve to push the wick up and form airflow paths between the two components (see FIGS. 2A and 2B). However, this was found to have a negative effect of increasing the thermal pathway from the heater to the wick. In this respect, the dimple structures not only increase the thermal mass of the part but increase the length of the path that heat has to travel from the heat source to the wick. They also create a specific heat flux (W/m²) between the heat transfer unit and the wick. It is desirable to improve the transfer of heat from the heat source to the wick thereby increasing the efficiency of vaporisation of the liquid.

It is an object of the present disclosure to provide an improved vapour generating device, in particular an e-cigarette device, and disposable cartridges for use with said device that aim to overcome, or at least alleviate, the above-mentioned drawbacks.

SUMMARY OF THE DISCLOSURE

A first aspect of the present invention provides a cartridge for a vapour generating device, the cartridge being configured to thermically connect to a base part having at least one heat source, the cartridge comprising:

- a liquid store for containing a vapour generating liquid and having a liquid outlet;
- a vaporization chamber in communication with the liquid store via the liquid outlet; and
- a fluid transfer medium provided in the vaporization chamber for absorbing liquid transferred to the vaporization chamber via the liquid outlet, wherein at least part of a surface of the fluid transfer medium is structured to form at least one air flow channel within the fluid transfer medium.

The fluid transfer medium may comprise at least one woven or non-woven material, wherein at least a part of a surface of the material is structured to form the at least one air flow channel. The woven or non-woven fluid transfer medium may be comprised of, for example, cotton or fibre glass or porous ceramic.

The fluid transfer medium may comprise a vaporization surface, and the vaporization surface may be structured to form the at least one air flow channel. The at least one air flow channel may be formed in the vaporization surface.

In use, the fluid transfer medium is configured to be heated directly or indirectly by the heat source comprised in the base part when the cartridge is thermically connected to the base part. When the fluid transfer medium is heated in this way, liquid absorbed by the fluid transfer medium is also heated, and liquid that is sufficiently heated will undergo a phase change to form a vapour. It is thus possible to define an “evaporation zone” of the fluid transfer medium, being the part of the liquid-filled fluid transfer medium volume where the temperature under operation is sufficiently high for evaporation to occur.

Vapour that is generated within the evaporation zone expands and moves through the fluid transfer medium to escape from the fluid transfer medium through at least a portion of the surface of the fluid transfer medium, where it joins the main air flow through the cartridge. Thus, one boundary surface of the evaporation zone can be thought of as an evaporation surface through which the generated vapor escapes. The term “vaporization surface” is used herein to refer to this evaporation surface, being the portion of the surface of the fluid transfer medium from which vapour escapes in use. Structuring the vaporization surface to include at least one air flow channel may thus increase the area of the vaporization surface, which may improve the efficiency of vapour escape. It will be appreciated that the above explanation is a simplification of the complex fluid mechanics governing vaporization of e-liquids in porous media (such as the fluid transfer medium), and that in reality vapour does not evaporate only at the vaporisation surface. Rather, vapor is mainly generated from the liquid that is close to the heat source, and this generated vapour moves through the fluid transfer medium to exit the fluid transfer medium via the vaporisation surface. The air flow channels discussed herein can thus assist in guiding the generated vapor to enter the main airflow through the vapour transfer channel within the cartridge.

The cartridge may further comprise a thermal interface membrane operable to conduct heat from the heat source in the base part to the vaporization chamber when the cartridge is thermically connected to the base part. The fluid transfer medium is heated indirectly via the thermal interface membrane and not directly via the heat source to evaporate the e-liquid within the fluid transfer medium, leading to considerable advantages in terms of safety, temperature control and reliability of the cartridge and the device.

Preferably, an intended lower surface of the fluid transfer medium remote from the liquid store is provided with the structured surface. For example, the structured surface may comprise a heater interface surface, being the surface intended in use to be heated indirectly or directly by the heat source in the base part. Thus, the at least one air flow channel may be formed in the heater interface surface. The structured surface may comprise at least two adjacent portions of the fluid transfer medium being provided in different planes to create the air flow channel therebetween.

Alternatively, or additionally, the structured surface may be spaced from the heater interface surface. For example, a side surface of the fluid transfer medium may comprise the structured surface. Alternatively or additionally, an interior surface of the fluid transfer medium may comprise the structured surface. Such a surface may not be directly heated by the heat source in the base part when in use, but may nevertheless permit vapour escape and thus may comprise part of the vaporization surface of the fluid transfer medium.

A surface of the fluid transfer medium may be structured to include a plurality of air flow channels.

The structured fluid transfer medium may comprise at least one non-woven material, the structured surface of the non-woven material being formed by at least one of press moulding, cutting, bending, folding, wet laying, lamination, melt blowing, spin bonding, embossing and partial weaving/stitching. The structured fluid transfer medium may comprise a porous ceramic material.

In a preferred embodiment, at least two fluid transfer mediums are provided comprising a first fluid transfer medium having the structured surface and a second transfer medium without a structured surface, the first fluid transfer medium being located furthest from the liquid store. Preferably, the first structured fluid transfer medium is thinner than the second non-structured fluid transfer medium.

The material of the first and the second fluid transfer medium may be the same or different. More preferably, the first fluid transfer medium has a lower hydraulic permeability than the second fluid transfer medium. The hydraulic permeability of the first fluid transfer medium is preferably le⁻⁷to le⁻⁴mm².

In a preferred embodiment, at least one support member is provided for at least partially supporting the fluid transfer medium to prevent or reduce its deformation, preferably wherein the at least one support member is provided for at least the structured part of the fluid transfer medium.

The at least one support member may comprise at least one of a housing surrounding the fluid transfer medium, in particular the structured fluid transfer medium, and a pin or strut extending partially or fully through or under the fluid transfer medium, in particular the structured fluid transfer medium.

Alternatively, or additionally, the at least one support member may comprise a reinforcing porous scaffold provided below, above or through the structured fluid transfer medium, in particular the non-woven structured wick. Preferably, the porous scaffold comprises porous material having a higher rigidity than the structured wick but that is still low enough to be formed.

Preferably, the porous scaffold is a mesh, more preferably being a stainless steel mesh. A preferred scaffold material is fine grade stainless steel mesh (304, 304L, 316, 316L, 310s, (04L, 430 etc.,). However, other suitable mesh materials include, for example, those of Iconel™, titanium and nickel. It is preferable for the mesh to have a wire diameter from 10-400 μm, preferably being in the range 20-100 μm with a nominal aperture of between 0.01-0.9 mm, preferably 0.02-0.1 mm. The mesh may be provided with any type of weave known in the art, such as plain weave, reverse Dutch weave, Twill weave, plain Dutch weave, Hollander weave, Twill Dutch weave, Crimp graphic weaves and other multiplex weaves.

Preferably, the reinforcing scaffold material and the wick are simultaneously pressed/formed to provide the reinforced structured wick.

The cartridge may also be provided with a thermal interface membrane extending at least partially across the structured surface of the fluid transfer medium.

The cartridge has a vapour flow channel extending from an inlet, through the vaporisation chamber to an outlet. The at least one airflow channel may extend substantially parallel with the predominant direction of airflow through the vaporization chamber.

A second aspect of the present invention provides a vapour generating device comprising: a base part having at least one heat source and a power supply and a cartridge according to the first aspect of the invention thermically connected to the base part. The structured surface of the fluid transfer medium may face the heat source or may be spaced from the heat source.

Preferably, the vapour generating device comprises an electronic cigarette.

As used herein, the term “electronic cigarette” may include an electronic cigarette configured to deliver an aerosol to a user, including an aerosol for inhalation/vaping. An aerosol for inhalation/vaping may refer to an aerosol with particle sizes of 0.01 to 20 μm. The particle size may be between approximately 0.015 μm and 20 μm. The electronic cigarette may be portable.

In general terms, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour can be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms ‘aerosol’ and ‘vapour’ may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user.

The structured fluid transfer medium provided in the cartridge of the device may be at least partially deformable on contact with the heat source to conform with the profile of the heat source. Alternatively, the structured fluid transfer medium may be rigid and non-deformable, e.g. a porous ceramic.

It is preferable for a footprint area of the heater interface surface of the fluid transfer medium to be substantially the same as a footprint area of the heat source that is brought into contact therewith. A thermal interface membrane may be provided between the structured fluid transfer medium and the heat source.

Preferably, the at least one air flow channel within the fluid transfer medium extends axially or parallel with the vapour flow channel of the cartridge that extends between the inlet and outlet.

It is to be appreciated that the cartridge and the base part may include any one or more components conventionally included in a vapour generating device. The inlet may be provided at the base of the cartridge, at the side or at the top of the cartridge. An appropriate channel flows from the inlet, through the vaporisation chamber and to the outlet, the second portion of the fluid transfer medium preferably traversing the channel.

The base part of the device may include a power supply unit, e.g. a battery, connected to the heat source. In operation, upon activating the electronic cigarette, the power supply unit electrically heats the heat source, such as a heating element, of the base part, which then provides its heat by conduction to a heat transfer unit. The heat transfer unit, in turn, provides the heat to the fluid transfer medium resulting in vaporization of the liquid absorbed therein. As this process is continuous, liquid from the liquid store is continuously absorbed by the transfer medium. Vapour created during the above process is transferred from the vaporization chamber via the vapour flow channel in the cartridge so that it can be inhaled via the outlet by a user of the device. Once the liquid in the liquid store is used up, the cartridge may be disconnected from the base part and a new cartridge fitted, enabling the reuse of the base part.

The heat source of the base part may comprise a protruding heater extending from the base part so that, in use, the heater extends into the chamber of the cartridge deforming the membrane around the heater.

The power supply unit, e.g. battery, may be a DC voltage source. For example, the power supply unit may be a Nickel-metal hydride battery, a Nickel cadmium battery, or a Lithium based battery, for example a Lithium-Cobalt, a Lithium-Iron-Phosphate, a Lithium-Ion or a Lithium-Polymer battery. The base part may further comprise a processor associated with electrical components of the electronic cigarette, including the battery.

The cartridge may further comprise: a cartridge housing at least partially including the liquid store and the vaporization chamber, and the vapour flow channel extending along the cartridge housing and in fluid communication with the vaporization chamber. The cartridge housing may have a proximal end configured as a mouthpiece end which is in fluid communication with the vaporization chamber via the vapour flow channel and a distal end associated with the base part. The mouthpiece end may be configured for providing the vaporized liquid to the user.

In one embodiment, the liquid store may be provided in the main body of the cartridge with the vapour flow channel extending from an inlet at the base and one side of the cartridge, along the base of the cartridge to the vaporization chamber and up one side of the cartridge to the outlet located centrally at the mouthpiece end. Alternatively, the liquid store may be disposed around the vapour outlet channel.

The cartridge housing may be made of one or more of the following materials: aluminium, polyether ether ketone (PEEK), polyimides, such as Kapton®, polyethylene terephthalate (PET), polyethylene (PE), high-density polyethylene (HOPE), polypropylene (PP), polystyrene (PS), fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), polyoxymethylene (POM), polybutylene terephthalate (PBT), Acrylonitrile butadiene styrene (ABS), Polycarbonates (PC), epoxy resins, polyurethane resins and vinyl resins.

According to a third aspect of the invention we provide a cartridge for a vapour generating device, the cartridge being configured to thermically connect to a base part having at least one heat source, the cartridge comprising:

- a liquid store for containing a vapour generating liquid and having a liquid outlet;
- a vaporization chamber in communication with the liquid store via the liquid outlet; and
- a fluid transfer medium provided in the vaporization chamber for absorbing liquid transferred to the vaporization chamber via the liquid outlet, wherein the fluid transfer medium is structured to form at least one vapour generation feature.

The vapour generation feature may be operable to increase a vaporization surface area of the fluid transfer medium.

The fluid transfer medium may comprise a vaporization surface, and the vaporization surface may be structured to form the at least one vapour generation feature.

The fluid transfer medium may comprise a heater interface surface, being the surface intended in use to be heated by the heat source in the base part (via the thermal interface membrane, if present). The at least one vapour generation feature may be formed in the heater interface surface.

Alternatively, or additionally, the at least one vapour generation feature may be spaced from the heater interface surface. For example, a side surface of the fluid transfer medium may be structured to form the at least one vapour generation feature. Alternatively or additionally, an interior surface of the fluid transfer medium may be structured to form the at least one vapour generation feature. Such a surface may not be directly heated by the heat source in the base part when in use, but may nevertheless permit vapour escape and thus may comprise part of the vaporization surface of the fluid transfer medium. The one or more vapour generation features may be spaced 100-500 μm from the heater interface surface.

A portion of the fluid transfer medium comprising the heater interface surface may comprise a protrusion. The heater interface surface may be formed on a face of the protrusion, such that the plane of the heater interface surface is spaced away from the main body of the ceramic wick and is the most prominent part of the wick. One or more vapour generation features may be formed on a side surface of the protrusion.

The fluid transfer medium may comprise a plurality of vapour generation features.

The vapour generation feature may comprise one or more air flow channels. The air flow channels may be through channels extending through the bulk of the fluid transfer medium, or may be non-through channels extending into the bulk of the fluid transfer medium, or may be surface channels. The one or more air flow channels may each comprise an inlet and an outlet that are both in fluid communication with the vaporization chamber. The one or more air flow channels may be as described above in connection with the first aspect of the invention.

The vapour generation feature may comprise one or more cutaway portions. The cut away portions may have a generally V-shaped cross-section and may cut into the fluid transfer medium by between 1%-40% of its radius (or equivalent radius) at the plane of cutting. The V can have an angle of between 1%-70% and more preferably between 10-60%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates schematically a plan view of a vapour generating device according to one embodiment of the present invention;

FIG. 1B is an expanded front cross-sectional view through the upper part of the vapour generating device shown in FIG. 1A;

FIG. 2A is a schematic drawing of an embossed heat transfer unit according to the prior art;

FIG. 2B is a schematic cross-sectional diagram illustrating the heat transfer unit of FIG. 2A positioned between a heat source and liquid source of a vapour generating device;

FIG. 3 is a schematic diagram of the arrangement of component parts of a vapour generating device according to an embodiment of the invention;

FIG. 4A illustrates a method of manufacture of an embossed fluid transfer medium for a cartridge according to the present invention;

FIG. 4B is an electron micrograph of the embossed fluid transfer medium produced according to the method of FIG. 4A;

FIG. 5 is an expanded view of an embossed fluid transfer medium for use in a cartridge according to an embodiment of the present invention;

FIG. 6A is a plan view of an upper part of a vapour generating device according to an embodiment of the present invention;

FIG. 6B is an expanded partial side cross-sectional view through the upper part of the vapour generating device shown in FIG. 6A;

FIG. 7 is a schematic diagram of the arrangement of component parts of a vapour generating device according to another embodiment of the present invention illustrating one support arrangement for a fluid transfer medium in the cartridge;

FIG. 8 is a schematic diagram of the arrangement of component parts of a vapour generating device according to a further embodiment of the present invention illustrating another support arrangement for a fluid transfer medium in the cartridge;

FIG. 9 is a schematic diagram of the arrangement of component parts of a vapour generating device according to yet another embodiment of the present invention illustrating a further support arrangement for a fluid transfer medium in the cartridge;

FIG. 10 is a schematic diagram illustrating the arrangement of a fluid transfer medium between a heat transfer element and a support;

FIG. 11 is a view of a non-woven fluid transfer medium provided with air flow channels;

FIG. 12 is a view of the non-woven fluid transfer medium of FIG. 11 provided with a support scaffold;

FIG. 13 illustrates a method of manufacture of the supported embossed fluid transfer medium of FIG. 12;

FIG. 14 illustrates a cross-sectional view of an upper part of a vapour generating device according to another example, as well as an expanded cross-sectional view illustrating air flow through a vapour transfer channel and a perspective view of a ceramic fluid transfer medium;

FIG. 15 is a further perspective view of the ceramic fluid transfer medium shown in FIG. 14;

FIG. 16A shows a perspective view of an alternative ceramic fluid transfer medium;

FIG. 16B shows a side view of the ceramic fluid transfer medium shown in FIG. 16B;

FIG. 17A shows a perspective view of a further ceramic fluid transfer medium;

FIG. 17B is a perspective view of the ceramic fluid transfer medium of FIG. 17A that is cut away along the line A-A;

FIG. 18 shows side, front and cross-sectional views of yet another example of a ceramic fluid transfer medium; and

FIG. 19 shows side, perspective and bottom-perspective views of a further example of a ceramic fluid transfer medium.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings and in which like features are denoted with the same reference numerals.

The present invention relates to a vapour generating device, particularly in the form of an electronic cigarette for vaporizing a liquid. The electronic cigarette can be used as a substitute for a conventional cigarette. The electronic cigarette comprises a base part 5 and a cartridge 2 (also referred to in the art as a “capsule” or “pod”) thermically connectable to the base part, as shown in FIGS. 1A and 1B of the accompanying drawings. The base part is thus the main body part of the electronic cigarette and is preferably re-usable.

The base part generally comprises a housing accommodating therein a power supply unit in the form of a battery connected to a heating element 20 located at a first end of the housing. The heating element may be in the form of a rigid protruding heater unit that protrudes out of the base part for partial receipt within the cartridge or capsule 2. The first end of the housing of the base part has an interface configured for matching a corresponding interface of the cartridge and may include one or more connectors for mechanically coupling the cartridge to the base part. The battery is configured for providing the heating element with the necessary power for its operation, allowing it to become heated to a required temperature. The battery may also be connected to a controller, enabling the required power supply for its operation and the controller may be operationally connected to the heater unit.

The cartridge (capsule or pod) comprises a cartridge housing having a proximal end and a distal end. The proximal end may constitute a mouthpiece end configured for being introduced directly into a user's mouth. Alternatively, a mouthpiece may be fitted to the proximal end. The cartridge comprises a base portion and a liquid storage portion 4, where the liquid storage portion comprises a liquid store or reservoir configured for containing therein the liquid L to be vaporized. The liquid L may comprise an aerosol-forming substance such as propylene glycol and/or glycerol and may contain other substances such as nicotine and acids. The liquid L may also comprise flavourings such as e.g. tobacco, menthol or fruit flavour. The liquid store may extend between the proximal end towards the distal end and a vapour transfer channel 24 may extend from an inlet 22 provided at the top of the cartridge (but may be provided elsewhere, such as the base or middle) to an outlet 26. A vaporisation chamber 6 extends between the liquid store and the base of the cartridge, the vaporisation chamber in fluid communication with the vapour transfer channel 24.

Additionally, the cartridge is provided with a fluid transfer medium 8, such as a porous wick which extends between the liquid store and the vaporisation channel. The fluid transfer medium may comprise any suitable porous substance, such as a non-woven or woven material. Examples of suitable materials include cotton, fabric and porous ceramic.

Upon connection of the interfaces between the cartridge and the base part of the device, the heater unit protrudes into the chamber immediately below a base of the porous wick, thereby enabling heating of the liquid in the wick until the liquid is transformed into vapour. A thermal interface membrane 10 may be provided between the heater and the porous wick. The membrane is a flexible, thin membrane and may be configured to ensure rapid and even heating of the target in an accurate and defined geometry. The thermal interface membrane 10 may be comprised in the cartridge, and more specifically in the base portion of the cartridge. The vaporisation chamber may be located within the cartridge above the thermal interface membrane. Thus, upon connection of the interfaces between the cartridge 2 and the base part 5 of the device, the heater unit 20 deforms the thermal interface membrane 10 when it protrudes into the vaporisation chamber and the vaporisation chamber remains sealed within the cartridge by the thermal interface membrane. The heating element thus does not come into direct physical contact with either the wick or the liquid.

It is important to provide good contact between the heating element 20 in the base part 5 of the device and the fluid transfer medium 8 in the cartridge 2 with efficient air flow through these parts. The arrangement of a separate base part with heating element for connection to a cartridge containing the liquid to be vaporised results in greater heat losses due to the need to transfer heat through more material. This may be impeded further by the presence of a fluid transfer medium, such as the wick, which increases the thermal contact resistance and increases the input energy required to reach the boiling point of the liquid in the wick.

FIGS. 2A and 2B illustrate a prior art method to improve heat transfer between the heat source and the fluid transfer medium. The heat transfer unit 20a that is placed between the heat source 20 and the cartridge 2 is provided with dimples 20b extending upwardly therefrom to create air flow channels 100. This does provide for high heat fluxes at the liquid side 4 but increases the distance for energy transfer from the heat source to the liquid.

The present invention addresses this problem by improving air flow and interaction between the fluid transfer medium and the heating element, providing greater transfer of heat energy from the heat source through the fluid transfer medium to the liquid. This is achieved by the provision of structured wick. In particular, embodiments herein each provide a fluid transfer medium that is structured to form at least one vapour generation feature. The term “vapour generation feature” is used herein to mean a structural feature operable to increase a vaporisation surface area of the fluid transfer medium as compared with a fluid transfer medium of approximately the same shape that is absent such a feature. For instance, at least part of a surface of the fluid transfer medium may be structured to form at least one air flow channel within the fluid transfer medium and/or may be structured to comprise at least one cutaway portion. For example, air flow channels may be formed within the lower part of the wick. In this manner, dimples do not need to be provided in the heat transfer unit 20a, reducing the distance for energy transfer from the heat source to the liquid.

The general concept of the present invention is illustrated in FIG. 3 of the accompanying drawings. FIG. 3 illustrates the arrangement of a fluid transfer medium 8 interface membrane 10 and heater 20 in a device according to one embodiment of the invention. The fluid transfer medium in this example is in the form of a two separate layers 8a, 8b of a woven or non-woven fabric, comprising a thicker layer 8b of an unstructured wick of a non-woven material with a high permeability and a lower, thinner layer 8a comprising a structured wick of non-woven material with a lower permeability. This lower layer 8a is brought into thermal contact with the heater 20, via the thermal interface membrane 10, when the base part of the device is connected to the cartridge. The structured portion of the wick replicates the effect of the dimples 20b provided in the heat transfer unit of FIG. 2A. This allows for the contact area of the wick to be controlled, thereby controlling the heat flux, as well as generating airflow passages 100 within the system.

The shape or form of the structured wick layer 8a can be achieved through forming of non-woven or woven fabrics by a range of different methods. The structured surface is provided on at least one surface of the woven or non-woven fabric, preferably the surface that contacts the heat source, and may be obtained by press moulding, cutting, bending or during other fabrication methods such as wet laying, lamination, melt blowing, spin bonding, via methods such as embossing or partial weaving/stitching.

FIG. 4A illustrates one example of a method of forming a structured non-woven fabric for forming a wick 8a via a spunbonding process. Molten polymer is extruded through a spinneret 200 to deposit extruded, spun filaments onto a moving collecting belt 202 to form a continuous fibrous web. The fibrous web is subjected to thermal bonding (calendar bonding) using a heated rotating embossing cylinder 204 to provide a web of non-woven fibers 300 between areas where the fibres are thermally bonded 302, as shown in the electron microscope of FIG. 4B. FIG. 5 illustrates one example of embossed geometry which may be provided in a non-woven fabric according to the invention. However, it is to be appreciated that the fabric may be structured to form air channels therein using other methods, such as bending or folding into the desired shape.

It is to be appreciated that the material forming the structured wick 8a should be of a thin structure to enable it to be suitable for the manufacturing method. This compression of the material will result in it having a lower hydraulic permeability but the hydraulic permeability should be maintained between le−7 to le−4 mm²for efficient operation of the device. The inclusion of a second non-structured wick section or layer 8b (see FIG. 3) enables the correct permeability of the wick to be maintained.

FIGS. 6A and 6B illustrate the cartridge 2 of the invention in further detail and demonstrate how the positioning of the structured wick 8 in the vaporisation chamber 6 of the cartridge improves heating and air/vapour flow through the device (the separate wick layers 8a and 8b are not visible in these figures). The base part of the vapour generating device is omitted for the sake of simplicity but the positioning of the heating element 20 when the base part is connected to the cartridge 2 is shown. The cartridge is provided with an air inlet 22 that extends into the vaporisation chamber 6 and is in fluid communication with a channel 24 that extends up the side of the liquid reservoir 4 to an outlet 26 (see FIG. 6A). Drawing air through the outlet 26 causes air to enter at the inlet 22 pass through the vaporisation chamber 6 where liquid is heated by the heating element 20 via the wick 8 resulting in it evaporating and entering the vaporisation chamber and being delivered to the outlet 26 by flow through the channel 24.

The wick 8 is positioned in the vaporisation chamber 6 and pressed against the heating element 20 (via a thermal interface membrane 10, as discussed above with reference to FIG. 3). FIGS. 6A and 6B illustrate the arrangement for a L-shaped wick 8 but it is to be appreciated that the wick may be any shape, for example being formed of a planar sheet of non-woven or woven fabric or other porous material extending between the liquid store 4 and the vaporisation chamber 6 and in contact with the heating element 20. As shown in FIG. 6B, the lower part of the wick 8 is structured to form air flow channels 100 in the lower surface of the wick 8. Preferably these air flow channels 100 are provided in a transverse direction, being the same direction as the airflow through the vapour channel of the device. This allows for maximum interaction of the airflow with both the fluid transfer medium (wick) and the heat source while allowing for control of airflow distribution across these parts to obtain even vapor removal. Part of the incoming air flow may flow through the air flow channels 100 while the remainder flows around (e.g. over) the wick as air is drawn through the vapour transfer channel 24.

The surface of the wick from which vapour is released is also termed herein a “vaporization surface”. When the wick is heated by the heater unit 20, liquid held within the wick vaporises due to the heat, and the vaporised liquid escapes from the wick to be entrained by indrawn air flowing through the vaporisation chamber. The vaporisation surface is thus the portion of the surface of the wick from which vaporised liquid is released into the vaporisation chamber. It will be appreciated that the air flow channels 100 increase the total surface area of the vaporisation surface of the fluid transfer medium as compared with a fluid transfer medium that is absent such features, by increasing the area of the surface that is available for vapour release.

As discussed above in relation to FIG. 3, the cartridge according to the invention includes one layer of wick that is a non-woven or woven structured wick 8a and another larger wick 8b that is not structured and increases the overall permeability of the wick. Additionally, the structured wick 8a should not deform appreciably after repeated use and after long periods of saturation as this would reduce the efficiency of the device. In order to prevent this, preferred embodiments of a device according to the invention include a support structure for maintaining the air flow channels 100 within the structured wick 8a. One embodiment of a support structure 400 is shown in FIG. 7 in which the structured wick 8a is supported or constrained by a surrounding housing material 400 which prevents movement of the edges of the wick 8a.

The support structure may also pass partially or fully through or under the structured wick 8a to prevent its deformation. FIG. 8 shows an embodiment wherein the structured wick 8a is retained within a support housing 400 having support members 402 extending partially into the wick 8a from the walls of the housing 400. Alternatively, the support member 404 may extend fully through the structured wick 8a, as shown in FIG. 9. The support members may be, for example, in the form of pins or struts that extend into the wick.

FIG. 10 of the accompanying drawings is a schematic drawing illustrating yet another arrangement for the structured wick for a cartridge according to the invention. The wick 8 has a vertical and a horizontal dimension (vertical dimension only partially shown in FIG. 10) with the structured wick 8a being provided in the horizontal dimension that contacts the heating element or heat transfer unit 20, thereby providing air flow channels 100 between the wick and the heater. Additionally, a frame member 500 is provided above at least the horizontal dimension of the wick to resist upward movement of this part of the wick thereby assisting in the formation of a close contact between the structured wick and the heater when the base part of the vapor generating device is connected to the cartridge.

It is to be appreciated that the fluid transfer medium (i.e. wick) may be provided without any support or with the support housing 400 or frame member 500 described above. Additionally or alternatively, the fluid transfer medium may be provided with a support scaffold through the body of the material. In this respect, a non-woven material with airflow channels 100 formed therein may collapse after multiple uses. Therefore, it may be preferable to include a reinforcing material with a stiffness that is higher than that of the wick. This may be provided throughout the structured wick to reinforce the hardness of the wick and increase its longevity.

FIGS. 11 and 12 illustrate a non-woven structured wick 80a with and without a support scaffold 600. The structured wick 80a shown in FIG. 11 has air/vapour channels 100 but these may flatten or collapse completely after repeated use due to the structure being soft and compliant. The continuous cycling (heating/vaporizing) of the wick can result in thermal degradation and loss of the initial formed shape thus reducing the efficiency of the device. In contrast, the non-woven structured wick 80a of FIG. 12 is provided with a stainless steel mesh 600 throughout the body of the structured wick 80a to add rigidity to the wick and prevent collapse/closing of the airflow channels 100 through repeated use.

The support scaffold 600 may be placed above, below or throughout the wick. The support scaffold is a rigid porous scaffold structure to add rigidity to the structured wick while still allowing liquid permeation, having a stiffness much higher than the material of the wick but still low enough to be formed into the same shape as the structured wick. An example of a suitable and preferred scaffold material is fine grade stainless steel mesh (304, 304L, 316, 316L, 310s, (04L, 430 etc.,). However, other suitable mesh materials include, for example, those of Iconel™, titanium and nickel. The mesh can have a wire diameter from 10-400 μm, preferably being in the range 20-100 μm with a nominal aperture of between 0.01-0.9 mm, preferably 0.02-0.1 mm. The mesh may be provided with any type of weave known in the art, such as plain weave, reverse Dutch weave, Twill weave, plain Dutch weave, Hollander weave, Twill Dutch weave, Crimp graphic weaves and other multiplex weaves. As illustrated in FIG. 13 of the accompanying drawings, the mesh 600 is placed above the unstructured non-woven material 80 of the wick and the materials are simultaneously pressed into the required structure by passing between heated rotating embossing rollers 704 to form air channels in the wick.

The production of a structured wick with a reinforcing scaffold allows for finer structures with higher aspect ratios. These reinforced structured wicks do not loose their shape after a high number of heating cycles and thus retain the airflow channels allowing for constant draw pressure and aerosol collected mass (ACM) delivery.

Referring now to FIGS. 14 and 15, an alternative embodiment of a vapour generating device 200 will be described. The vapour generating device 200 is similar to that shown in FIGS. 6A and 6b, and like reference numerals are used to illustrate like elements where appropriate. As in the examples above, the vapour generating device 200 includes a base part 5 thermically connectable to a removable and possibly disposable cartridge 2. The base part includes a heater 20 together with a power source and control circuitry (not shown), whilst the cartridge 2 includes a liquid storage portion 4 such as a reservoir operable to hold a liquid L to be vaporised. A vapour transfer channel 24 extends from an inlet 22 to an outlet 26 via a vaporisation chamber 6.

The device 200 shown in FIG. 14 differs from that of FIGS. 6A and 6B in that the fluid transfer medium 800a comprises a porous ceramic material. The ceramic material is substantially rigid, and may have a porosity in the range of 30-80%, and for example between 50-70%. The ceramic material may have a pore size of between 10-80 μm, for example between 20-40 μm.

The ceramic fluid transfer element 800a is disposed in the cartridge with at least one face in fluid contact with the liquid L inside the reservoir 4. A seal 60 may be provided to prevent leakage of fluid from the reservoir. Fluid from the reservoir is absorbed by the porous ceramic material and wicked towards a heater interface surface 810 of the fluid transfer element 800a through the pores of the ceramic material. The heater interface surface 810 is located in proximity to the thermal interface membrane, such that heat is supplied to the heater interface surface 810 when the cartridge is connected to the base part 5 in the manner described above.

As is the case in the examples discussed above, a surface of the fluid transfer medium 800a shown in FIGS. 14 and 15 is structured to form at least one vapour generation feature that is operable to increase the vaporization surface area of the fluid transfer medium. In particular, the exemplary vapour generation feature includes one or more air flow channels 100, for example a plurality of air flow channels 100. In the specific example shown, the ceramic fluid transfer medium includes four air flow channels (only three of which are visible), but it will be appreciated that a different number of channels could be provided if required, depending on the size of channels and space constraints. Further, the vapour generation feature could include any other feature operable to increase the area of the vaporization surface, such as ribs, fins or pins.

As best seen in FIG. 15, the air flow channels 100 in this example are formed in the heater interface surface 810. The air flow channels 100 are surface channels having a generally U-shaped cross section. When the cartridge 2 is connected to the base part 5, the heater 20 deforms the thermal interface membrane 10 as it protrudes into the vaporisation chamber 6 to press the thermal interface membrane against the heater interface surface 810 of the ceramic wick 800a, so closing the channels to form through channels which have an inlet and an outlet within the vaporization chamber. These through channels may have a hydraulic conductivity in the region of 0.1 mm-1 mm, e.g. 0.2 mm, or 0.3 mm, or 0.4 mm, or 0.5 mm.

The air flow channels 100 may be oriented in any direction relative to the incoming flow of air through the vapour transfer channel 24. However, in the example shown the channels are oriented in substantially the same direction as the incoming airflow 820, which can improve the efficiency of vapour escape from the fluid transfer medium. Whatever the orientation of the air flow channels 100, part of the incoming air flow 820 may flow through the channels 100, while the remainder of the air flow 820 (and possibly the majority of the air flow) may flow around the fluid transfer medium.

To improve the flow of air around the fluid transfer medium, a portion of the fluid transfer medium comprising the heater interface surface may comprise a protrusion 830. The heater interface surface 810 may be formed on a face of the protrusion 830, such that the plane of the heater interface surface is spaced away from the main body of the ceramic wick and is the most prominent part of the wick. The heater interface surface 810 thus defines a footprint, and the area of the footprint may be substantially the same as the area of a footprint of the heater 20 in the base part, such that when the cartridge 2 is connected to the base part 5 heat from the heater 20 is supplied primarily to the heater interface surface rather than to the space around the fluid transfer medium.

At least one depression 840 may be formed on an opposing surface of the fluid transfer element. This opposing face is internal to the reservoir 4, and the depression may thus encourage liquid L within the reservoir towards a specific location within the reservoir, particularly when liquid levels are low. The depression may be located within the envelope formed by the protrusion 830, and may have a shape which is complementary to the shape of the protrusion 830 in order to encourage liquid towards a portion of the opposing surface which has the shortest wicking path to the heater interface surface. The depression may be shaped to ensure that thickness of the porous ceramic of the fluid transfer medium is substantially constant, taking into account the shape of the protrusion.

The wick may have an exterior geometry with dimensions of between 7-12 mm on one side, 3-6 mm one another side, and 2-6 mm on the last side.

FIGS. 16A and 16B show an alternative example of a ceramic fluid transfer element 800b which is similar to the ceramic wick shown in FIGS. 14 and 15. However, in addition to open channels 100 formed in the heater interface surface, the fluid transfer element includes additional vapour generation features that are spaced from the heater interface surface. These additional vapour generation features are structured in a surface that is spaced from the heater interface surface and so is not directly heated by the heat source in the base part when in use. Nevertheless, the vapour generation features are structured in a surface that permits vapour to escape from the porous ceramic during heating, and thus forms part of the vaporization surface of the fluid transfer medium. The additional vapour generation features are thus operable to further increase the vaporisation surface area of the fluid transfer medium.

In particular, the fluid transfer medium 800b is structured to include at least one, and in this example two, open channels 100a formed in a side surface of the wick. The side surface is, in the example shown, a external surface of a protrusion 830 of the type discussed above. Since the channels 100a are located above the plane of the heater footprint, they are not closed by the thermal interface membrane when the cartridge is connected to the base part, and thus remain open during use.

The fluid transfer medium 800b is further structured to include at least one, and in this example two, through channels extending through the bulk of the fluid transfer medium. The through channels each comprise an inlet and an outlet that are both in fluid communication with the vaporization chamber 6.

As discussed above, the air flow channels 100, 100a, 100b may be oriented in any direction relative to the incoming flow of air through the vapour transfer channel 24. However, in the example shown the channels are oriented in substantially the same direction as the incoming airflow 820, which can improve the efficiency of vapour escape from the fluid transfer medium. Whatever the orientation of the air flow channels 100, 100a, 100b, part of the incoming air flow 820 may flow through the channels 100, 100a, 100b, while the remainder of the air flow 820 (and possibly the majority of the air flow) may flow around the fluid transfer medium. The channels may have a hydraulic conductivity in the region of 0.1 mm-1 mm e.g. 0.2 mm, or 0.3 mm, or 0.4 mm, or 0.5 mm.

As discussed above, providing vapour generation structures such as air flow channels 100 on the heater interface surface (bottom face) of the wick, which is in direct contact with the thermal interface membrane and heating element during use, can improve the efficiency of vapour escape from wick. However, it can also lead to a problem of balance between the surface area in contact with the heat source and the perimeter/area available for vapor generation. In contrast, providing vapour generation structures that are spaced from the heater interface surface can increase the perimeter/area exposed to open air, from which vapor can escape whilst still maintaining a large contact area with the heat source.

To transfer the energy into the wick from the heater, via the thermal interface membrane, there is a requirement for large contact surface area (which is solid to solid contact), but to extract the generated vapor from the ceramic wick there ideally needs to be a large amount of exposed vaporisation surface area (which is solid to gas contact). The balance between these conflicting requirements can be improved by moving at least some of the vaporisation surface area out of plane with the heat transfer contact area. Thus, in the example shown in FIGS. 16A and 16B, instead of placing all the vapour generation features (channels) on the base of the wick where the heat transfer needs to occur (i.e. in the “vape plane”), at least some of the vapour generation features are placed a few hundred microns (e.g. 100-500 μm) above this “vape plane”. All the vapour generation features may be located above the heater interface surface, if required.

FIGS. 17A and 17B show a further example of a ceramic fluid transfer medium 800c in which all of the vapour generation features are moved out of the plane of the heater interface surface 810, such that the heater interface surface is not structured. In particular, the fluid transfer medium 800c includes a plurality of air flow channels 100c that are spaced from the heater interface surface 100c, e.g. a few hundred microns (e.g. 100-500 μm) above the heater interface surface. The air flow channels 100c are blind channels in that they do not extend through the ceramic wick from an inlet to a separate outlet. Nevertheless, they operate to permit vapour formed within the ceramic to escape, and thus increase the vaporisation surface area of the fluid transfer medium. The channels 100c can be considered as defined by a structured internal surface of the fluid transfer medium. The channels may have a hydraulic conductivity in the region of 0.1 mm-1 mm, e.g. 0.2 mm, or 0.3 mm, or 0.4 mm, or 0.5 mm.

FIG. 17B shows the wick of FIG. 17A with the heater interface surface cut away along line A-A to show the internal structure of the channels 100c. It can be seen that the channels extend into the body of the ceramic and terminate at a position that is spaced from a central region 850 of the wick leaving a channel-free area in the central region of the wick having a radius of, e.g., 0.5 mm-5 mm, or 1 mm-3 mm. This arrangement may reduce the potential impact of the channels on liquid that is wicked from the reservoir 4 towards the heater interface surface by providing an unhindered liquid path through the central portion 850 of the wick.

FIG. 18 shows a further variant of a ceramic fluid transfer medium 800d including a vapour generation feature in the form of an annular airflow channel 100d provided in a plane located above the heater interface surface, e.g. a few hundred microns (e.g. 100-500 μm) above the heater interface surface. The annular channel 100d is structured in the surface of the protrusion 830 such that it extends around the protrusion, surrounding a longitudinal axis 860 of the fluid transfer medium. Again, a central region 850 of the ceramic material is free of structured features, so as to permit a clear path for liquid to be wicked towards the heater interface surface 810. The annular channel may have a hydraulic conductivity in the region of 0.1 mm-1 mm, e.g. 0.2 mm, or 0.3 mm, or 0.4 mm, or 0.5 mm. A thermal interface membrane 10 and heater 20 are illustrated in FIG. 18 to show the relative positions in use. It will be appreciated however that in reality the heater would be comprised in the base part of the device, whilst the thermal interface membrane and the fluid transfer medium would be comprised within a cartridge of the type shown in FIG. 14.

FIG. 19 shows another example of a ceramic fluid transfer medium 800e including a vapour generation feature in the form of at least one, and in this example two, air flow channels 100e in a structured side surface of the fluid transfer medium 800e. The channels 100e are provided in a plane located above the heater interface surface, e.g. a few hundred microns (e.g. 100-500 μm) above the heater interface surface. The channels define cutaway portions of the protrusion with a generally V shaped cross section. The V shape can cut into the wick by between 1%-40% of its radius (or equivalent radius) at the plane of cutting. The V can have an angle of between 1%-70% and more preferably between 10-60%. A thermal interface membrane 10 and heater 20 are illustrated in FIG. 18 to show the relative positions in use. It will be appreciated however that in reality the heater would be comprised in the base part of the device, whilst the thermal interface membrane and the fluid transfer medium would be comprised within a cartridge of the type shown in FIG. 14.

All the examples of FIGS. 16A-19 show ceramic fluid transfer mediums which include at least one vapour generation feature spaced from the heater interface surface. Although the vapour generation features shown are channels, it will be appreciated that the surface of the fluid transfer medium could be structured to include features having a different shape, if required. By cutting channels, slits, holes, or other structures in a plane above the heating plane there is still the possibility for vapor to escape as there is reduced resistance (porous wick material) between the vapor generation location (e.g. heater interface surface) and a free air path, whilst not impacting on the area of the fluid transfer medium in close contact with the heater. A fluid transfer medium as shown in FIGS. 16A-19 thus has faces which are not in contact with the thermal interface membrane structured to increase the vapor surface area. In some examples they may also reduce a length of the vapor path from the heater interface surface to open air. The cuts or channels in the wick can be on multiple planes, and may be circumferential or not. As shown in FIGS. 16A, 16B and 19, the heater interface surface may also include one or more air flow channels or structures.

The skilled person will realize that the present invention by no means is limited to the described exemplary embodiments. In particular, it will be understood that the terms “horizontal” and “vertical” refer to the orientation shown in the Figures, which represents a typical use orientation, and are not intended to be limiting. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Moreover, the expression “comprising” does not exclude other elements or steps. Other non-limiting expressions include that “a” or “an” does not exclude a plurality and that a single unit may fulfil the functions of several means. Any reference signs in the claims should not be construed as limiting the scope. Finally, while the invention has been illustrated in detail in the drawings and in the foregoing description, such illustration and description is considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

A Cartridge for a Vapour Generating Device and a Vapour Generating Device

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