Patent ID: 12213525

DETAILED DESCRIPTION

FIG.1shows a cross-sectional view through an e-cigarette100in accordance with some embodiments of the disclosure. The e-cigarette comprises two main components or sections, namely a cartomizer200and a control unit300. As discussed in more detail below, the cartomizer200includes a chamber270defining a reservoir of source liquid, a heater (not shown inFIG.1) to generate vapor from the source liquid, and a mouthpiece. The liquid in the reservoir270(sometimes referred to as source liquid or e-liquid) typically includes nicotine in an appropriate solvent, and may include further constituents, for example, to aid aerosol formation, and/or for additional flavoring. The cartomizer200further includes a wicking element (wick)500, which provides a wicking, capillary or similar facility to transport a small amount of liquid from the reservoir270to a heating location on or adjacent the heater. The heater and the wick500may be collectively designated as an atomizer or vaporizer. The atomizer or vaporizer and the reservoir270may collectively be designated as an aerosol source. Therefore, the cartomizer200is the section of the e-cigarette100which, in this example, houses the atomizer and the aerosol source.

The control unit300includes a re-chargeable cell or battery350to provide power to the e-cigarette100, a printed circuit board (PCB) for generally controlling the e-cigarette (not shown inFIG.1), and a pressure sensor or airflow sensor345for detecting a user inhalation (via a pressure drop). When the heater receives power from the battery350, as controlled by the PCB in response to the sensor345detecting a user puff on the e-cigarette100, the heater vaporizes the liquid from the wick500and this vapor is then inhaled by a user through the mouthpiece.

For ease of reference, the x and y axes are marked inFIG.1. The x axis will be referred to herein as the width of the device (from side to side), while the y axis will be referred to herein as the height axis, where the cartomizer200represents the upper portion of the e-cigarette100and the control unit300represents the lower portion of the e-cigarette100. Note that this orientation reflects how a user holds the e-cigarette100during normal operation of the device, given that the wick500is located in the lower part of the reservoir270in the cartomizer200. Therefore holding the e-cigarette100in this orientation brings the wick500into contact with liquid at the bottom of the reservoir270. Other devices may have a wick oriented or positioned differently.

A z axis (not shown inFIG.1) is also assumed, which is perpendicular to the x and y axes shown inFIG.1. The z axis will be referred to herein as the depth axis. In this example the depth of e-cigarette100is significantly less than the width of the e-cigarette100, thereby resulting in a generally flat or planar configuration (in the x-y plane). Accordingly, the z axis can be considered as extending from face to face of the e-cigarette100, where one face may be regarded (arbitrarily) as the front face of the e-cigarette and the opposing face as the back face of the e-cigarette100.

The cartomizer200and the control unit300are detachable from one another by separating in a direction parallel to the y-axis, but are joined together when the device100is in use so as to provide mechanical and electrical connectivity between the cartomizer200and the control unit300. When the e-liquid in the reservoir270has been depleted, the cartomizer200can be removed and a new cartomizer attached to the control unit300. Accordingly, the cartomizer200may sometimes be referred to as a disposable portion of the e-cigarette100, while the control unit300represents a re-usable portion. In other examples, the cartomizer200may be configured such that the reservoir270, when empty, can be refilled with liquid, so that the cartomizer can also be re-usable.

FIG.2is a perspective external view of the cartomizer200of the e-cigarette ofFIG.1in accordance with some embodiments of the disclosure. This external view confirms that the depth of the cartomizer200(and the e-cigarette100as a whole), as measured parallel to the z axis, is significantly less than the width of the cartomizer200(and the e-cigarette100as a whole), as measured parallel to the x axis.

The cartomizer200comprises two main portions (at least from an external viewpoint). In particular, there is a lower or base portion210and an upper portion220. The upper portion220provides a mouthpiece250for the e-cigarette. When the cartomizer200is assembled with the control unit300, the base portion210of the cartomizer sits within the control unit300, and hence is not externally visible, whereas the upper portion220of the cartomizer protrudes above the control unit300, and hence is externally visible. Accordingly, the depth and width of the base portion210are smaller than the depth and width of the upper portion220, to allow the base portion210to fit within the control unit300. The increase in depth and width of the upper portion220compared with the base portion210is provided by a lip or rim240. When the cartomizer200is inserted into the control unit300, this lip or rim240abuts against the top of the control unit300.

As shown inFIG.2, the side wall of base portion210includes a notch or indentation260for receiving a corresponding latching member from the control unit300. The opposite side wall of the base portion210is provided with a similar notch or indentation to likewise receive a corresponding latching member from the control unit300. It will be appreciated that this pair of notches260on the base portion200(and the corresponding latching members of the control unit) provide a latch or snap fit connection for securely retaining the cartomizer200within the control unit300during operation of the device.

As also shown inFIG.2, the bottom wall211of the base portion210includes two larger holes212A,212B on either side of a smaller hole214for air inlet into the cartomizer during user inhalation. The larger holes212A and212B are used to provide positive and negative electrical connections from the control unit300to the cartomizer200, in particular to the heater and the PCB. When a user inhales through the mouthpiece250and the device100is activated, air flows into the cartomizer200through the air inlet hole214. This incoming air flows past the heater (not visible inFIG.2), which receives electrical power from the battery in the control unit300so as to vaporize liquid delivered to the heater from the reservoir by the wick. This vaporized liquid is then incorporated or entrained into the airflow through the cartomizer, and hence is drawn out of the cartomizer200through mouthpiece250for inhalation by the user.

FIG.3is an exploded view of the cartomizer200of the e-cigarette ofFIG.1in accordance with some embodiments. The cartomizer includes a shell410, a vent seal420, an inner frame430, a heating coil450located on a wick500, a primary seal460(also referred to as the cartomizer plug), a printed circuit board (PCB)470and an end cap480. The view ofFIG.3shows the above components exploded along the longitudinal (height or y) axis of the cartomizer200.

The cap480is formed from substantially rigid plastic such as polypropylene and provides the base portion210of the cartomizer. The cap480is provided with two holes260,261on each side. The lower hole260is for latching the cartomizer200to the control unit300. The upper hole261is for latching the end cap480to the shell410to complete assembly of the cartomizer410and retain the various components shown inFIG.3in the correct position in the assembled cartomizer410.

Above the end cap is located the PCB470, which includes a central air hole471to allow air to flow through the PCB into the atomizer (the end cap480is likewise provided with a central air hole, shown inFIG.2as feature214). In accordance with some embodiments, the PCB does not contain any active electrical components, but rather provides a circuit or conductive path between the control unit300and the heater450.

Above the PCB470is located the primary seal460, which has two main portions, an upper portion which defines (in part) an atomizer chamber465, and a lower portion462which acts as an end seal for the reservoir270. Note that in the assembled cartomizer200, the reservoir of e-liquid is located around the outside of the atomizer chamber, and the e-liquid is prevented from leaving the cartomizer (at least in part) by the lower portion462of the cartomizer plug460. The cartomizer plug460is made from a material that is slightly deformable, to allow the lower portion462to be compressed a little when inserted into the shell410, and hence provide a good seal to retain the e-liquid in reservoir270.

Two opposing side walls of the atomizer chamber465are provided with respective slots569into which the wick500is inserted. This configuration locates the heater450, which is positioned on the wick500, near the bottom of the atomizer chamber to vaporize liquid introduced into the atomizer chamber465by the wick500. In some embodiments, the wick500is made of glass fiber rope (i.e. filaments or strands of glass fiber twisted together), and the heater coil450is made of nichrome (an alloy of nickel and chromium). However, various other formats of wick and heater are known and could be used in the cartomizer200; these are discussed further below. The heater coil450has a wire lead dropping down from the wick at each end, by which the heater450is able to be electrically connected to the battery. The wick500has a flared shape, in that its end portions which reach into the reservoir270have an enlarged cross-section compared to its central portion around which the heater coil450is wrapped. The shape of the wick500is discussed further below.

The cartomizer plug460and the wick/heater assembly are surmounted by the inner frame430, which has three main sections. The inner frame430is substantially rigid, and may be made of a material such as polybutylene terephthalate. The lowermost section436of the inner frame430engages with the lower portion462of the cartomizer plug460, while the middle section434completes the atomizer chamber465of the cartomizer plug460. In particular, the inner frame430provides a top wall of the atomizer chamber, and also two side walls that overlap with the two side walls of the atomizing chamber465provided by the cartomizer plug460. The final section of the inner frame430is an airflow tube432that extends upwardly from the top wall of the atomizing chamber (part of the middle section434) to connect with an outlet hole in the mouthpiece250. The tube432provides a passage for vapor produced in the atomizing chamber465to be drawn out of the e-cigarette100by inhalation through the mouthpiece250.

The vent seal420is inserted around the top of the airflow tube432to provide a seal between the inner frame and the outlet hole in the mouthpiece250. The vent seal420is made of a suitably deformable and resilient material such as silicone. Lastly, the shell410provides the external surface of the upper portion220of the cartomizer200, including the mouthpiece250, and also the lip or flange240, and also an outer wall for the reservoir270surrounding the atomizer chamber465. The shell410is formed of a substantially rigid material, such as polypropylene. The lower section412of the shell410, below the lip240, sits inside the end cap480when the cartomizer200has been assembled. The shell410is provided with a latch tab413on each side to engage with the hole261on each side of the end cap480, thereby retaining the cartomizer200in its assembled condition.

The airflow passage through the assembled cartomizer enters a central hole in the cap480(not visible inFIG.3) and then passes through the hole471in the PCB. The airflow next passes up into the atomizer chamber465, which is formed as part of the cartomizer plug460, flows around, over and past the assembly of the wick500and the heater450, and through the tube432of the inner frame430(and through vent seal420), and finally exits through the hole (not shown) in the mouthpiece250.

The reservoir270of e-liquid is contained in the space between this airflow passage and the outer surface of the cartomizer200. Thus the shell410provides the outer walls (and top) of the reservoir270, while the lower section436of the inner frame in conjunction with the base portion462of the primary seal460and end cap480provide the bottom or floor of the reservoir270. The inner walls of the reservoir are provided by the atomizing chamber465of the primary seal460, in cooperation with the middle section434of the inner frame, and also the airflow tube432of the inner frame430and the vent seal420. In other words, the e-liquid is stored in the reservoir space between the outer walls and the inner walls. The wick500passes through apertures in the inner walls so that liquid from the reservoir270can penetrate inside the inner walls by way of absorption and wicking within the wick500to the heater450. Other liquid penetration into the air flow passage should be minimized to inhibit liquid from leaking out of the hole in the mouthpiece250.

The capacity of the space forming the reservoir270is typically of the order of 2 ml in accordance with some embodiments, although it will be appreciated that this capacity will vary according to the particular features of any given design. Note that unlike for some e-cigarettes, the e-liquid reservoir270is not provided with any absorbent material (such as cotton, sponge, foam, etc.) for holding the e-liquid. Rather, the reservoir chamber contains the liquid alone so that the liquid can move freely within the reservoir270. Such a configuration may be referred to as a “free liquid” reservoir, and has advantages including generally supporting a larger capacity, and also making the filling procedure less complex.

FIGS.4A and4Billustrate the wick/heater assembly being fitted into the cartomizer plug in accordance with some embodiments of the disclosure. The wick/heater assembly is formed from the heater wire450and the wick500. In this example, the wick500comprises glass fibers formed into a generally elongate shape. The heater450comprises a coil of wire551wound around a central portion of the wick500. At each end of the coil551there is a contact wire552A,552B, which together act as the positive and negative terminals to allow the coil551to receive electrical power.

As visible inFIG.4A, the primary seal460includes the base portion462and the atomizing chamber465. The atomizing chamber465comprises four walls in a rectangular arrangement, a pair of opposing side walls568, and a pair of opposing front and back walls567. Each of the opposing side walls568includes a slot569which has an open end at the top (and in the centre) of the side wall, and a closed end564relatively near the bottom of the atomizing chamber465. The two slots569extend more than halfway down their respective side walls568.

Referring now toFIG.4B, this shows the wick/heater assembly fitted into the atomizing chamber465of the cartomizer plug. In particular, the wick/heater assembly is positioned so that the wick500extends between, and protrudes out of, the two opposing slots569A,569B, with the heater coil (not shown inFIG.4B) located between the slots569A,569B so that it is inside the atomizer chamber465. The wick500is lowered until it reaches the closed end564of each slot. In this position, the coil551is then located entirely in the atomizing chamber465and only the wick500that extends out of the slots reaches into the reservoir area270. It will be appreciated that this arrangement allows the wick500to draw liquid from the reservoir270into the atomizing chamber465for vaporization by the wire heater coil551. Having the wick500located near the bottom of the atomizing chamber465, and more particularly also near the bottom of the reservoir270, helps to ensure that the wick retains access to liquid in the reservoir even when the level of liquid drops as the liquid is consumed.FIG.4Balso shows how the heater contact wires552A,552B extend below the primary seal460.

FIGS.5A and5Billustrate the inner frame and the vent seal being fitted into the cartomizer plug in accordance with some embodiments of the disclosure. Thus, as previously described, the inner frame430comprises a base section436, a middle section434and an air tube432located at the top of the inner frame. The base section contains two slots671A,671B extending in a horizontal sideways direction (parallel to the x axis). As the base section436of the inner frame is lowered down past the atomizing chamber465, the portions of the wick500that extend out from each side of the atomizing chamber465pass through these slots671A,671B, thereby allowing the base section of the inner frame to be lowered further until it is received in the lower portion462of the cartomizer plug.

As noted above, the middle section434of the inner frame complements and completes the atomizing chamber465of the cartomizer plug460. In particular, the middle section provides two opposing side walls668and a top wall or roof660. The latter closes the top of the atomizing chamber465, except in respect of the air tube432which extends up from the atomizing chamber465to the outlet hole of the mouthpiece250.

Each of the opposing side walls668includes a slot669A,669B which extends upwards (parallel to the y axis) from the bottom of the side wall to the closed end of the respective slot. Accordingly, as the base section436of the inner frame is lowered down past the atomizing chamber465, the portions of the wick500that extend out from each side of the atomizing chamber465pass through these slots669A,669B (in addition to slots671A,671B). This therefore allows the side walls668of the inner frame430to overlap the side walls568of the cartomizer plug. Further downward movement of the inner frame430is prevented once the closed end of slots669A,669B contacts the wick500, which coincides with the base section436of the inner frame being received into the lower portion462of the cartomizer plug. At this stage, the combination of cartomizer plug460, heater/wick assembly, and inner frame430, has been formed as shown inFIG.5B, and the vent seal420can now be fitted onto the air tube (pipe)432of the inner frame430.

FIG.6Aillustrates the combination of the inner frame430, wick/heater assembly, and primary seal460being fitted into the shell410. The various walls that define the reservoir270are thereby brought into conjunction to create the reservoir, so the cartomizer200is now ready for filling with source liquid.

FIG.6Bshows the cartomizer200assembled up to this point. Filling with liquid is performed, as indicated by arrows701A,701B, through holes582A and582B in the primary seal460and through slots671A,671B in the inner frame430. To complete the cartomizer200as it is depicted inFIG.2, the PCB470is installed in a rectangular indentation584in the underside of the primary seal460, and the end cap480is fitted over the end of the cartomizer plug460and the lower section412of the shell410. In this fully assembled state (seeFIG.2), the end cap480covers and therefore closes the holes582A,582B in the cartomizer plug that were used for filling the liquid reservoir270. Accordingly, the reservoir270is now fully sealed, apart from the opening on each side of the atomizing chamber465through which the wick500passes into the atomizing chamber465.

An electronic cigarette may be configured otherwise than in the example described thus far while including a flared wick.FIG.7shows an exploded view of components of a cartomizer according to a further example. Many of the components are similar to those of theFIGS.1-6example, but differently shaped so that the cartomizer has a more elongate and less flat shape. The cartomizer is composed of a base part1that forms the lower face of the cartomizer. A bottom plug2closes the lower end of a reservoir, which is otherwise comprised by a wall portion3in the form of an annular outer wall that engages into the plug2and a top plug or seal4which engages into the top end of the wall portion3. A flared wick500has a heater coil450wrapped around it, and is located within the volume defined by the wall portion3. A tubular air channel5sits inside the wall portion3so that it surrounds the wick500and heater450, partitioning these parts from the reservoir and forming an atomizing chamber. The tubular channel5comprises an oppositely disposed pair of slots5A extending upwardly from its lower edge, and the end portions of the wick500are receiving in these slots so as to reach into the reservoir for the purpose of collecting liquid from the reservoir. A vent seal6is pushed into an opening4A in the top plug4; this is aligned with the tubular channel5A. A hollow shell7forms the exterior of the cartomizer200, and receives the other components within itself to align the air channel formed by the tubular channel5and the vent seal6with an air outlet7A in a mouthpiece7B of the shell7. The base part closes the lower end of the shell7. A lower portion7C of the shell7is recessed compared to the mouthpiece7B, to be received inside an upper part of a control unit, similar to the connected arrangement of theFIGS.1-6example.

Embodiments of the disclosure are not limited to these example devices, and may be implemented in vapor provision systems configured in other ways.

It will be appreciated from these examples that the reservoir of an electronic cigarette can comprise a relatively small volume, formed by closely spaced walls. The wick necessarily protrudes into this volume to be able to absorb the liquid contained in the reservoir, but there may be very little space available to accommodate it. Accordingly, when the reservoir is filled, air bubbles may be trapped around the wick, such as between the ends of the wick and the outer wall of the reservoir. Surface tension of the liquid may also inhibit flow of the liquid around the wick, both during filling and during subsequent use. Proper filling of the reservoir may thus be prevented, giving a reduced effective reservoir capacity. Also, absorption of liquid by the wick may be inhibited if liquid does not fully surround the wick ends owing to air bubbles and surface tension effects.

To address this, it is proposed to provide a shaped wick which flares out at the portion or portions that extend into the reservoir. This increased width or cross-section improves absorption of liquid by the wick so that liquid transfer from the reservoir to the heater is enhanced, and consistent vapor production can be maintained.

The wick or wicking element can comprise any suitable porous material, having a pore structure that provides a wicking capability to transport liquid absorbed by one part of the material (a part inside a reservoir of liquid) to another part (adjacent a heating element) by a capillary action. Example materials include fiber-based structures such as bundles, strands, threads, ribbons or ropes formed from woven, non-woven, spun, plaited or twisted fibers of cotton, wool, glass or artificial fibers, or solid/rigid non-fiber-based materials with integral interstitial pores, such as porous ceramics. The manner in which the flared shape is provided will be appropriate to the material used for the wick.

A porous ceramic or other solid material may be fabricated directly into the required flared shape, for example by molding or machining. A density of the wick material may be substantially the same at the flared end parts as in the part adjacent the heating element. Alternatively, the size and/or distribution of the pores may differ at the end part compared to the heating portion, for example with a larger pore size and/or a higher density of pores at the end part or parts, and smaller pore size and/or lower density of pores in the part adjacent the heating element. In other words, the porosity varies across the wick, with a higher porosity in the flared part or parts intended to be immersed in the reservoir and a lower porosity in the vicinity of the heating element. The larger volume of porous material, and optionally the larger pore size/higher pore quantity/higher porosity, of the flared portion(s) will all aid in improving the ability of the wick material to absorb liquid from the reservoir.

For a fibrous wick, the cross-section at the reservoir ends may be enlarged compared to the heating part by fraying or unraveling fibers which are woven, spun, twisted and/or bundled together, and spreading or splaying the resulting separated fibers or strands of fibers away from each other. Individual fibers may be separated from each other, or individual plies comprising two or more fibers may be separated from each other, or a combination of the two, depending on the configuration of the fibers. Any such arrangement which increases the fiber-to-fiber spacing of at least some of the adjacent fibers in the enlarged part of the wick might be employed. This has the effect of reducing the density of the wick material in the flared sections, since the fibers have a larger separation and are less tightly packed together compared to the heater portion. A similar effect may be achieved by using a relatively loosely spun, woven or twisted length of fibers, or a loosely packed bundle of fibers, and compressing or squashing one part to form a heater section. The remaining uncompressed part or parts will be splayed out compared to the compressed part and hence have a larger cross-section. The compression or confinement of the heater portion of the wick may be maintained by tying or wrapping further fibers around the wick fiber or fiber bundle; these securing fibers may be the same as or different from the wick material. Alternatively, the heating element may be used to compress the fibers if it has the form of a wire coil; the wire may be tightly wrapped around a fiber or fiber bundle to squeeze the fibers together at the same time as forming a coil.

FIG.8shows a schematic side view of a simple example flared wick generally in accordance with embodiments of the disclosure, shown inside a partial cross-sectional view of a section of a cartomizer. The wick500has a central portion H disposed inside an atomizing chamber465, extending across the chamber perpendicularly to the direction of airflow through the chamber (indicated by the arrow A). A heater450in the form of a wire coil is wrapped around the central portion H. Accordingly this part of the wick500may be considered as a heater portion, a heated portion or a heating element portion, or alternatively an atomizing portion. The atomizing chamber465is bounded by an annular wall270b(shown in cross-section), on the far side (outside) of which lies a reservoir270of source liquid. An outer annular wall270aforms the outside of the reservoir270, and possibly also the exterior wall of the cartomizer. The reservoir is hence also annular and surrounds the atomizing chamber465. The reservoir270contains only source liquid, so that the liquid is free-flowing within the reservoir.

The inner annular wall270bhas two oppositely arranged apertures270cin it, aligned perpendicularly to the airflow A, and the wick250has end portions E1, E2which are continuous with the heater portion H, but extend through the apertures270cto reach into the interior of the reservoir270for the purpose of absorbing liquid held in the reservoir270. The end portions E1, E2may therefore be considered as liquid-collecting portions, liquid absorbing portions, or reservoir portions. The wick has an axis L indicated by a dotted line which is designated as a longitudinal axis, although this does not imply that the extent of the wick along the direction of the axis L is necessarily its largest dimension. In this example, the longitudinal axis is arranged orthogonally to the direction of airflow A. Also, the longitudinal axis is straight, and the heater portion H and the end portions E1, E2are arranged contiguously along the axis L so that the wick has an overall straight linear configuration, and might be considered as elongate. The longitudinal axis may be curved or bent in other configurations, however.

Each of the end portions E1, E2has a flared (or, conversely, tapered) shape, in that a cross-section through the wick in a plane perpendicular to the longitudinal axis L is larger along at least one dimension at an end portion E1, E2than at the heater portion H. This may be thought of as the wick having a length (along the L direction), and a width at its end portions which is larger than a width at its heater portion, where the width is orthogonal to the length. Similarly or alternatively, a perimeter (which may be a circumference if the wick has a generally circular cross-section or rod-like format) of the end portions is larger than a perimeter of the heater portion. The heater portion, being the part inside the atomizing chamber, on a first side of the wall separating the atomizing chamber from the reservoir, may have a constant or average width, diameter, perimeter, circumference or cross-sectional area over its length, and each end portion, being the part in the reservoir, on a second side of the separating wall, may have a greatest width, diameter, perimeter, circumference or cross-sectional area which is larger than the corresponding constant or average parameter for the heater portion. The flared shaped may also be described as the wick having a width, perimeter or cross-sectional area which increases from a first value at a heater portion of the wick, or at a position where the wick aligns with the aperture in the separating wall, to a second value at an end, liquid-collecting, portion of the wick, where the second value is larger than the first value. The increase may be in a single dimension only orthogonal to the axis L (such as thickness only or height only), or may be in two dimensions orthogonal to the axis L and to each other (thickness and height). Both the thickness and the height may conveniently be designated as a width, being a dimension orthogonal (transverse) to the longitudinal axis of the relevant portion of the wick, namely a local longitudinal axis. In wicks with a circular cross section, the width is a diameter. An increase over two dimensions may or may not be such as to maintain the same cross-sectional shape (but not size) from the heater portion to the end portions. Note that the greatest (widest) part of the end portion(s) of the wick may or may not be at its physical extremity, depending on the external shape adopted for the end part.

The various measures of width, diameter, thickness, height, perimeter, circumference and cross-sectional area are all of interest, and a constant (linear) or varying (non-linear) increase in any of these measures over at least part of the longitudinal extent of a wick end portion can be implemented to provide a flared shape. The measures are all features of the cross-section of the wick at the location of interest, so may collectively be designated as cross-sectional parameters, cross-sectional measures, cross-sectional values, or cross-sectional numerical values. Within this set of parameters, the width measures (thickness, height, diameter) are linear measures, so may be considered as cross-sectional dimensions, since “dimension” typically denotes a linear extent.

FIG.8Ashows a schematic side view of an example wick to illustrate the flared configuration. A central heater portion H has a longitudinal extent L1along the axis L, a width W1perpendicular to the axis L and a perimeter P1in a plane perpendicular to the axis L. On each side of the central portion, the width (and hence also the perimeter) increases to form end portions E1and E2which terminate to a maximum width W2greater than W1and a maximum perimeter P1greater than P2. A first end portion E1has a length L2along the axis L, and the second end portion E2has a length L2along the axis L. The boundary or junction between the central portion H and each end portion E1, E2is indicated as “a”, and marks the point where the wick is intended to pass through an aperture in a wall of a reservoir (correspondingly, a wall of the atomizing chamber housing the heater). This junction or boundary may be considered as a “neck” of the end portion, beyond which the wick flares outwards. The junctions “a” will align with the reservoir wall, and indicate the location where the heater portion of the wick transitions into an end portion. The two widths W1and W2are separated in the longitudinal dimension L along the length of the generally elongate wick, where L is orthogonal to the width dimension. The increase in dimension to form the flare may be linear so that the sides of the wick in the end portions are straight, and angled outwards with respect to the central portion, as in theFIG.8example. In theFIG.8Aexample, the increasing width is nonlinear so that the width increases more rapidly towards the ends of the wick, giving curved sides to the wick500so that each end has a “trumpet” shape. A combination of linear and nonlinear increases may be used to give a desired profile for the wick500. The increase in width/perimeter/cross-section of the end portion compared to the central portion may commence at the location of the boundary “a”, or at any location after the point “a”, towards the physical end of the wick, remote from the heater portion and within the end portion, or before the point “a”, away from the physical end of the wick and within the heater portion.

Note that in theFIGS.8and8Aexamples, the largest width/perimeter (W2or P2) for the end portions is at their extremity, but this need not be the case.

Regular shapes such as inFIGS.8and8Amay be obtained for a solid wick material such a porous ceramic. Wicks formed from fibers or fiber bundles may have a less regular, more ragged shape, within a flared outline, but the overall impression will be the same, with a clearly increased width and perimeter for the end portions compared to the heater portion.

The greater dimension for the end portions may be larger or smaller compared to the central portion as required. Any flaring of the end sections can have a positive effect on wicking, with greater flaring producing a more noticeable effect. So, width (or depth or thickness) W2is greater than W1such that W2/W1has any value greater than 1. For example, W2/W1may be at least 1.25, or at least 1.5, or least 2, or at least 3, or at least 4 or at least 5. In terms of circumference or perimeter (in other words, the measurement around the wick at the position of the width of interest), P2is greater than P1such that P2/P1has any value greater than 1. For example, P2/P1may be at least 1.25, or at least 1.5, or at least 2, or at least 3, or at least 4, or at least 5. In terms of cross-sectional area orthogonal to the longitudinal axis, the maximum area A2of the end portion is greater than the area A1of the heater portion such that A2/A1has any value greater than 1. For example, A2/A1may be at least 1.25, or at least 1.5, or least 2, or at least 3, or at least 4 or at least 5.

In many examples, the heater portion will be of a generally constant thickness or width, so that the width W1, the perimeter P1and the cross-sectional area A1are the same in the middle of the wick (and at other intermediate locations) as at the neck location where the end portion begins. However, this need not be the case, and the heater portion may have a variable cross-section. In this case, a value for W1or P1or A1for comparison with the equivalent parameter W2or P2or A2for the end portion can be taken from the width or the perimeter or the cross-sectional area at the neck.

FIG.9shows a perspective view of an example wick with a generally circular cross-section, and in which the increased parameter or parameters to form the flared ends E1, E2is in two dimensions, so that the circular cross-section is preserved from the central portion H to the end portions E1, E2. The increase is non-linear so that the wick as a curved profile. The overall shape of the wick may be considered as a “dumb-bell” shape.

FIG.10shows a perspective view of an example wick in which the increase to form the flared shape is in one dimension only. The central portion H has a square cross-section. In the end portions E1, E2, the width in the thickness direction (as illustrated, into the plane of the page) stays the same as for the central portion H, but the width in the height direction (as illustrated, vertically in the plane of the page) increases linearly over the longitudinal extent of the end portions. The overall shape of the wick may be considered as a “bow-tie” shape.

As a further example, a wick with a central square portion as inFIG.10may have a two-dimension increased width as inFIG.9, to preserve the square cross-section within the end portions. Also, a flat-sided heater portion may expand into curved or rounded end portions, or a curved or rounded heater portion may expand into flat end portions. There is no requirement to preserve any shape or geometrical features from the heater portion to the end portions, merely that there is at least one transverse dimensional increase to achieve the flared shape.

FIG.11shows a perspective view of an example wick formed from a bundle of fibers. In the central portion H, the fibers are spun or twisted together. In the end portions E1, E2, the fibers are separated from each other and spaced apart. Hence the width of the end portions is larger than the width of the central portion. Such a configuration can be achieved by taking a length of bundled fibers previously twisted, spun, intertwined, woven or plaited together, and unraveling the fibers at each end of the length to splay them into a flared shaped. Alternatively, individual fibers may be taken, and twisted, spun, intertwined, woven or plaited together in a central region to form a narrower bundle for the heater portion of the wick. Alternatively, as mentioned above, the central narrower bundle might be formed by binding, tying or wrapping a central region of the bundle to compress and confine the fibers in that region, using additional fibers of a same or a different type, or by using the coils of a heating element.

The examples thus far have comprised wicks with a central heater portion and two end portions, in a linear alignment with the heater portion in the centre between the end portions. Such an arrangement is convenient for an annular reservoir surrounding an atomizing chamber, where it is desired for the wick to reach across the chamber and into the reservoir on two opposite sides. However, the present embodiments are not limited in this regard, and the wick may comprise any number of flared end portions intended for immersion in a reservoir and contiguous with a heater portion intended for location in an atomizing chamber.

FIG.12shows a simplified partial cross-section of an example wick with one flared end. The wick comprises a heater portion H linearly arranged continuously with a single end portion E1. The heater portion H is provided with a heating element450in the form of a wire coil wrapped around the wick; these parts are disposed in an atomizing chamber465. A wall270bdivides the atomizing chamber465from a reservoir270, and the wick is arranged to extend through an aperture270cin the wall so that the flared end portion E is situated inside the reservoir.

FIG.13shows a simplified view of an example wick with four flared ends, shown in transverse cross-section through an aerosol source (i.e. perpendicular to the airflow direction, which will be into the plane of the page). It is known to configure an atomizer to comprise a pair of wicks, each with a heating element, and arrange them in a cross shape with respect to air flow through an atomizing chamber surrounded by an annular reservoir, so that both ends of each wick reach into the reservoir. The present disclosure invention may be applied to such an arrangement, either by flaring the ends of two separate two-ended wicks, or by providing a single cross-shaped wick in which each of the four arms terminate in a flared end portion.FIG.13shows an example of this configuration. The wick500has a central portion H in the form of a cross, which is surrounded by a heating element450which may comprise one, two or more wire coils, for example. This portion is located in an atomizing chamber which is divided from an annular reservoir270by an inner annular wall270b. An outer annular wall270aforms the exterior of the reservoir270. The inner wall270bhas four apertures270c, aligned with the four arms of the wick500so that the arms extend through the apertures270cinto the reservoir, wherein one or more transverse dimensions of the arms are increased to form flared end portions E1-E4for liquid absorption. The wick might be considered to have a “Maltese cross” shape.

For wick configurations having more than one flared end portion, each end portion may or may not be the same size and shape. End portions of the same size and shape provide a symmetric wick, whereas differing end portions (by size and/or shape and/or amount of flare) provide an asymmetric wick which may be preferred in some cases, depending on the configuration and arrangement of the atomizing chamber and the reservoir. For end portions or arms with differing amounts of flare, each arm will have a width or perimeter or cross sectional area which is greater than that of the heater portion, but may differ from that of the other arm or arms.

The examples already presented have each assumed an atomizer configuration (the combination of a wick and a heater) in which a heating element is provided externally to a wick, for example the heater is a coil wrapped around a (central) heater portion of the wick. The disclosure is not limited in this regard, however. As an alternative, the heating element may be embedded within the porous material of the wick, at the location of the heater portion intended to be arranged within an atomizing chamber.

FIG.14shows a simplified side view of an example wick with an embedded heater. The wick500has a central heater portion H and two flared ends E1, E2. Note that the ends terminate in a rounded shape, and are hence an example in which the maximum width/area/perimeter of the flared ends is located inwardly from the physical extremity of the wick. A heater450in the form of a wire is disposed within the wick material of the heater portion H, and has follows a serpentine path in this region, with two external leads552A and552B extending from the serpentine section to the exterior of the wick500for electrical connection of the heater450. The heater may have any shape within the wick material, and may be formed from wire or from a conductive layer, for example. Similarly, external heating elements may take any shape and are not limited to coils.

Note that while the Figures depict various examples of flared wicks in simple outline which may suggest a solid wick material such as porous ceramic, any of the various shapes and configurations, plus others within the scope of the disclosure which will be apparent to the skilled person, can be configured in a fiber-based format or a sold material format.

Further, while the end portion(s) of the wick and the heater portions are adjacent to one another, they need not be arranged along a straight line. In other words, the longitudinal axis (L inFIGS.8and8A) need not be a straight line. There may be one more bends in the axis, for example, a two-ended wick may have a U-shape, in which the end portions form an angle of around 90 degrees to the heater portion. Nevertheless, the end portions will still have a width greater than a width of the heater portion, measured orthogonally with respect to the local longitudinal axis regardless of any bends, turns or angles in the axis as a whole. Also, one may define the flared, increased width of the end portion or portions of the wick as the end portion having a maximum width, perimeter or cross-sectional area that is larger than a width, perimeter or cross-sectional area of the wick at the point (the neck of the end portion) where it is intended to pass through an aperture in the wall of the atomizing chamber to reach into the reservoir.

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 utilized 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.