Classifications

• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24F—SMOKERS' REQUISITES; MATCH BOXES; SIMULATED SMOKING DEVICES
  • A24F40/00—Electrically operated smoking devices; Component parts thereof; Manufacture thereof; Maintenance or testing thereof; Charging means specially adapted therefor
  • A24F40/50—Control or monitoring
  • A24F40/53—Monitoring, e.g. fault detection
• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24F—SMOKERS' REQUISITES; MATCH BOXES; SIMULATED SMOKING DEVICES
  • A24F40/00—Electrically operated smoking devices; Component parts thereof; Manufacture thereof; Maintenance or testing thereof; Charging means specially adapted therefor
  • A24F40/10—Devices using liquid inhalable precursors
• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24F—SMOKERS' REQUISITES; MATCH BOXES; SIMULATED SMOKING DEVICES
  • A24F40/00—Electrically operated smoking devices; Component parts thereof; Manufacture thereof; Maintenance or testing thereof; Charging means specially adapted therefor
  • A24F40/40—Constructional details, e.g. connection of cartridges and battery parts
• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24F—SMOKERS' REQUISITES; MATCH BOXES; SIMULATED SMOKING DEVICES
  • A24F40/00—Electrically operated smoking devices; Component parts thereof; Manufacture thereof; Maintenance or testing thereof; Charging means specially adapted therefor
  • A24F40/40—Constructional details, e.g. connection of cartridges and battery parts
  • A24F40/48—Fluid transfer means, e.g. pumps
  • A24F40/485—Valves; Apertures

Definitions

• the present invention relates to an electronic aerosol provision device.
• a typical electronic aerosol provision device includes an internal air path which provides a channel between one or more inlets and one or more outlets.
• a user of the electronic aerosol provision device inhales on the air outlet(s) to create an airflow through the device along the channel from the air inlet(s) to the air outlet(s).
• An electronic aerosol provision device generally also includes a source (precursor) material which is used for forming a vapour or aerosol.
• a source (precursor) material which is used for forming a vapour or aerosol.
• some devices include a reservoir of liquid and a heater which is used to vaporise liquid from the reservoir.
• a heater may be used to generate volatiles from a solid material, and these in turn form a vapour or liquid.
• the liquid or solid material may be provided in a replaceable cartridge.
• the vapour or aerosol is usually generated in, or migrates into, the channel from the air inlet(s) to the air outlet(s), and is conveyed by the airflow along the channel and out through the air outlet(s) for inhalation by a user.
• the user experience of such an electronic aerosol provision device is dependent upon the vapour or aerosol that exits the device for inhalation.
• the approach described herein provides an electronic aerosol provision system comprising an air pathway between an air inlet and an air outlet and a vaporiser for generating vapour into the air pathway.
• the air pathway between the air inlet and the vaporiser is configured to support laminar air flow.
• the approach described herein provides an electronic aerosol provision system, comprising an air pathway between an air inlet and an air outlet, a vaporiser for generating vapour into the air pathway, and a facility for adjusting the air pathway to control turbulence within the air pathway.
• Figure 1 shows an example electronic aerosol provision system.
• Figure 2 shows an electronic aerosol provision system having a linear airflow channel configured to support laminar airflow according to the approach described herein.
• Figure 3 shows distributions of aerosol particle sizes generated by an electronic aerosol provision system such as shown Figure 1.
• Figure 4 shows distributions of aerosol particle sizes generated by an electronic aerosol provision system such as shown Figure 2.
• Figure 5 shows an electronic aerosol provision system having a smoothly curved airflow channel configured to support laminar airflow according to the approach described herein.
• Figure 6 shows an electronic aerosol provision system having a facility for adjusting the air pathway to control turbulence according to the approach described herein.
• Figure 7 shows another electronic aerosol provision system having a facility for adjusting the air pathway to control turbulence according to the approach described herein.
• the present disclosure relates to electronic aerosol provision systems, which may also be referred to as electronic vapour provision systems, e-cigarettes, and so on.
• electronic aerosol provision systems which may also be referred to as electronic vapour provision systems, e-cigarettes, and so on.
• the terms“e-cigarette”,“electronic cigarette”, “electronic aerosol provision system” and“electronic vapour provision system” may be used interchangeably unless the context demands otherwise.
• the terms“device” and“system” may be used interchangeably, for example, an“electronic aerosol provision system” should be regarded as the same as an“electronic aerosol provision device”, unless the context demands otherwise.
• vapour and “aerosol”, and related terms such as “vaporise”, “aerosolise”, and“volatlise”, may likewise be used interchangeably unless the context demands otherwise.
• Such electronic aerosol provision systems/devices are often provided in modular form, for example, comprising a control unit and a cartomiser (the latter being a combination of a cartridge and a vaporiser).
• the term electronic aerosol provision system/device is used herein to denote one or more modules (such as the control unit) that act (comprise components) to generate an aerosol or vapour.
• Such a system/device may be configured to receive one or more additional modules, for example, a module (cartridge) containing liquid or other precursor to be vaporised, or may be provided in combination with one or more additional modules.
• One common configuration for an electronic aerosol provision system/device having a modular assembly is to comprise a reusable part (the main control unit) and a replaceable (disposable) cartridge part, also referred to as a consumable.
• the replaceable cartridge part often contains the vapour (aerosol) precursor material and may (in some implementations) also contain a vaporiser (aerosoliser) to form a cartomiser.
• the reusable part often contains a power supply, for example, a rechargeable battery, and control circuitry for the
• the reusable part may contain a user interface for receiving user input and displaying operating status characteristics
• the replaceable cartridge part may contain a temperature sensor for helping to control the temperature of the vaporiser.
• a cartridge part is usually electrically and mechanically coupled to a control unit for use.
• the vapour precursor material in a cartridge is exhausted (fully consumed), or the user wishes to switch to a different cartridge having (for example) a different vapour precursor material, the cartridge may be removed from the control unit and a replacement cartridge provided in its place.
• Devices conforming to this type of two-part modular configuration are sometimes referred to as two-part devices.
• Some of the example devices/systems described herein are based on an elongated two-part device/system that utilises disposable cartridges. However, it will be appreciated that the approach described herein may also be adopted for different configurations of an electronic aerosol provision system/device, for example, single-part devices or modular devices comprising more than two parts, refillable devices and single-use disposable devices. In addition, the approach described herein may be applied to devices/systems having other geometries (not necessarily elongate), for example, based on so-called box- mod high performance devices that typically have more of a box-like shape.
• FIG. 1 is a schematic cross-sectional representation of a first electronic aerosol provision device 20.
• the e-cigarette 20 comprises two main sections, namely a control section 22 and a cartridge section 24.
• the cartridge section and the control section are separate parts which can be detached from one another.
• the control part 22 and the cartridge part 24 are releasably coupled together at an interface 26.
• the cartridge part 24 may be detached from the control part 22.
• the detached cartridge may then be disposed of (if fully depleted) and a replacement cartridge coupled to the control part.
• the same cartridge part 24 may be refilled and re-attached to the control part 22.
• the cartridge part 24 might be refillable in situ, i.e. while still attached to the control part 22 (in which case the cartridge section 24 might potentially be permanently attached to the control section 22).
• the interface 26 generally provides a structural (mechanical), electrical and airflow path connection between the control section 22 and the cartridge section 24.
• the interface 26 may provide appropriately arranged electrical contacts for establishing various electrical connections between the two sections.
• the interface may support (define) an airflow channel (path) between the two sections as appropriate.
• control section 22 and the cartridge section 24 might be fixed together (rather than being detachable); as noted above, this might be the case when the cartridge section 24 is re-fillable in situ.
• a vaporiser may be provided in the control section 22 rather than in the cartridge section 24, in which case the interface 26 might be configured to support the transfer of a vapour precursor (such as a liquid) from the cartridge section 24 to the control section 22 - but without necessarily supporting the transfer of electrical power from the control section 22 to the cartridge section 24.
• the interface 26 may support a wireless transfer of power from the control section to the cartridge section, for example, based on electromagnetic induction. In this case, a direct physical (electrical) connection between the control section 22 and the cartridge section 24 may not be provided. Furthermore, in some implementations, in some
• the airflow path through the electronic aerosol provision device 20 might not go through the control section 22, hence the interface 26 might not include an airflow channel connection between the control section 22 and the cartridge section 24.
• the skilled person will be aware of various other potential modifications.
• the cartridge section 24 comprises a cartridge housing 62 which may be made of plastic or any other suitable material.
• the cartridge housing 62 supports other components of the cartridge section 24 and provides a mechanical interface with the control section 22 as part of interface 26.
• the cartridge section includes an airflow channel (or pathway) 72 and a mouthpiece 70 which defines an air outlet 71 from the airflow channel 72.
• a reservoir 64 that contains a liquid to provide a vapour precursor material; this is often referred to as an e-liquid.
• the liquid reservoir 64 in the device of Figure 1 has an annular shape about (around) the airflow channel 72.
• the shape of the reservoir 64 is defined by an outer wall, provided by the cartridge housing 62, and an inner wall that forms the outside or boundary of the airflow channel 72 through the cartridge section 24.
• the reservoir 64 is closed at each end to retain the e-liquid, by mouthpiece 70 at the downstream end of the cartridge section 24 and by the housing 62 forming interface 26 at the upstream end.
• the cartridge section 24 further comprises a wick (liquid transport element) 66 and a heater (vaporiser) 68.
• the wick 66 extends transversely across the cartridge airflow channel 72, i.e. perpendicular to the airflow direction along channel 72.
• Each end of the wick is configured to draw liquid from the reservoir 64 through one or more openings in the inner wall of the liquid reservoir 64.
• the e-liquid infiltrates the wick 66 and is drawn along the wick 66 by capillary action (i.e. wicking).
• the heater 68 may comprise an electrically resistive wire coiled around the wick 66, for example a nickel chrome alloy (Cr20Ni80) wire, and the wick 66 may comprise a glass fibre bundle or a cotton fibre bundle.
• the wick might be made of ceramic
• the wick and heater coil might be arranged longitudinally rather than transversely
• there might be multiple heater coils 68 there might be multiple wicks 66
• the heater 68 may have a planar configuration, and so on.
• electrical power may be supplied to the heater 68 to vaporise an amount of e-liquid (vapour precursor material) drawn to the vicinity of the heater 68 by the wick 66.
• the vaporised e-liquid then becomes entrained in air drawn along the cartridge airflow channel 72 towards the mouthpiece outlet 70 for user inhalation.
• the rate at which e-liquid is vaporised by the vaporiser (heater) 68 generally depends on the amount of power supplied to the heater 68, as well as the wicking or liquid transport capacity of wick 66. In some devices, the rate of vapour generation (the vaporisation rate) can be adjusted by changing the amount of power supplied to the heater 68, for example through the use of pulse width and/or frequency modulation techniques.
• the e-liquid vapour formed by the heater 68 cools in the airflow channel 72 and at least partially condenses into particles (small droplets of liquid), thereby forming an aerosol. It is this aerosol that is then inhaled by a user through mouthpiece outlets 71.
• the control section 22 shown in Figure 1 comprises an outer housing 32 with an opening that defines an air inlet 48 for the e-cigarette 20, a battery 46 for providing electrical power to operate the e-cigarette 20, control circuitry 38 for controlling and monitoring the operation of the e-cigarette 20, a user input button 34 and a visual display indicator 44.
• the outer housing 32 is configured to receive the cartridge section 24, thereby providing a smooth integration (union) of the two sections or parts at the interface 26.
• the outer housing 32 may include clips and/or slots and/or any other suitable engagement features for receiving corresponding features of the cartridge section 24.
• the battery 46 is generally rechargeable such as through a charging connector in the control section housing 32, e.g. a USB connector (not shown in Figure 1).
• the user input button 34 may be used to perform various control functions.
• the display 44 may (for example) comprise one or more LEDs for displaying information about the charge status of the battery 46 or any other suitable information or indication.
• the user input button 34 and the display 44 may be integrated as a single component.
• the control circuitry 38 is suitably configured (programmed) to control the operation of the electronic cigarette, for example to regulate the supply of power from the battery 46 to the heater 68 for generating vapour.
• the air inlet 48 connects to an airflow path 50 through the control section 22.
• the control part section path 50 in turn connects to the cartridge airflow channel 72 via the interface 26 when the control part 22 and cartridge part 24 are connected together.
• the airflow path 50 is configured so that the airflow through air inlet 48 is perpendicular to the airflow through the air outlet 71 during a user inhalation.
• the air inlet 48 is arranged on a side of the outer housing 32 (rather than the base).
• Such an air inlet may be termed a side hole.
• the airflow path 50 incorporates a corner or angle whereby the airflow during an inhalation transitions sharply from a first direction of airflow from the air inlet 48 to the corner to a second direction of airflow from the corner to the interface 26.
• the second direction of travel is perpendicular to the first direction of travel.
• Figure 2 is a schematic cross-sectional representation of a second electronic aerosol provision device 200.
• the components of the e-cigarette 200 of Figure 2 are generally the same as or similar to those described in relation to the Figure 1 (and labelled with like reference numbers), and so these components will not be discussed again.
• the second e-cigarette 200 of Figure 2 comprises an air inlet 248 in the base (or bottom) of the e-cigarette (where the orientation of an e-cigarette is defined in the conventional manner such that the mouthpiece 71 is at the top).
• control section airflow pathway 250 and the cartridge section airflow pathway 72 are coaxially aligned such that there is a straight air path along the length of the airflow channel.
• the airflow channels 250, 72 of electronic vapour provision device 200 are aligned such that airflow through the device from the air inlet 248 to the vaporiser 68 and then out through the mouthpiece 70 follows a substantially straight line (linear) pathway, i.e. heading in substantially a single direction, without changing direction, curving, bending, etc..
• Figure 2 shows one example in which the airflow pathways in the control section 22 and in the cartridge section 24 have a coaxial (co-aligned) configuration
• e-cigarette 200 is shown as having two modules (cartridge part 24 and control part 22)
• other implementations with a coaxial configuration for airflow pathways 52 and 72 may be implemented as a one-piece device, or else as a system comprising more than two modules.
• a laminar airflow also referred to herein as a linear airflow
• the air generally all flows in parallel in the same direction.
• the airflow velocity along the pipe has a radial profile according to distance from the centre of the pipe. The air flowing along the central axis of the pipe flows most quickly, while the airflow velocity then gradually drops with radial distance away from the centre to a zero velocity adjacent the edge or wall of the pipe in a region referred to as the boundary layer.
• This turbulent airflow (also referred to herein as non-linear airflow) is created by, and reflects, localised variations in air pressure and other instabilities. For example, air flowing around (but close to) an obstruction may have a higher pressure than air flowing further away from the obstruction; this may then be balanced by a region of relatively low pressure immediately after the obstruction. Localised movements of air in effect seek to rebalance the air pressure variations, and thereby introduce turbulence into the airflow.
• turbulence may also arise even in an axially aligned channel shown in Figure 2.
• the air is pushed through a pipe too quickly (i.e. with too great a pressure difference)
• the high level of radial shear resulting from different axial velocities at different radial distances out from the centre of the channel disrupts the airflow, leading to instabilities and other forms of turbulence.
• a dimensionless parameter known as the Reynolds number (R) is often used to characterise the laminar and turbulent flow regimes.
• a low Reynolds number will generally produce laminar flow, while a high Reynolds number will generally produce turbulent flow.
• the transition between laminar flow and turbulent flow might typically occur for R in the range 2000-3000 (although this transition point is typically sensitive to various factors, and may lie outside the above range in some circumstances). Note that increasing the flow speed increases the Reynolds number, and hence may induce a transition to turbulent flow, as noted above. In contrast, increasing the viscosity will decrease the Reynolds number; this can be regarded as a higher viscosity damping out turbulent motion.
• Figures 3 and 4 are graphs showing the frequency distributions of particle sizes produced by the first and second example e-cigarettes, namely the side-hole device 20 of Figure 1 and the linear flow device 200 of Figure 2 respectively.
• the particle size refers to the size of particles or droplets in the vapour or aerosol exiting the device through air outlets 71.
• Each graph shows ten repeated measurements of the particle size distribution.
• the laminar (non-turbulent) airflow may form an aerosol having a smaller particle size than the non-laminar (turbulent) airflow because the turbulence causes more collisions between aerosol particles, and such collisions may lead to coagulation between particles and hence a growth in particle size.
• the airflow is laminar, coagulation among particles might be reduced since the airflow is substantially all in parallel, aligned with the axial direction. Consequently, there is less mixing in the airflow, and hence less potential for coagulation.
• an enhanced user experience can be achieved by an electronic vapour provision system that generally provides an aerosol having a smaller particle size for inhalation by the user.
• this user preference for a smaller particle size may arise from one or more factors, such as easier absorption of the particles by tissue, increased lightness and/or diffusiveness of the particles, greater uniformity (consistency) of the particles, increased travel distance of the particles, etc..
• the airflow configuration of the e-cigarette 200 of Figure 2 is advantageous with respect to the airflow configuration of the e-cigarette 20 of Figure 1 , because the straight airflow channel 250 of Figure 2 helps to provide laminar airflow, and hence a smaller particle size, compared with the angled airflow channel 50 of Figure 1.
• the airflow may have both laminar and turbulent components. Increasing the proportion of laminar components at the expense of the turbulent components should still help promote a reduced particle size and hence an improved user experience. Accordingly, the benefits of providing a laminar flow are not binary (all or nothing), but rather can be realised by incrementally increasing the proportion of laminar flow in a given device.
• FIG. 5 is a schematic cross-sectional representation of a third electronic aerosol provision device 500.
• the components of the e-cigarette 500 of Figure 5 are generally the same as or similar to those described in relation to the Figure 1 (and labelled with like reference numbers), and so these components will not be discussed again.
• the e-cigarette 500 of Figure 5 comprises an airflow pathway 550 in the control section 22 which is side-opening 548 (like the e-cigarette 20 of Figure 1), but having a smooth, continuous curve for the airflow channel 550 between the air inlet 548 (side-hole) and the interface 26.
• Configuring the airflow pathway 550 to have such a continuous curve, rather than a sharp corner or angle, helps to support laminar air flow.
• an air pathway 550 which imparts a gradual change in direction of the airflow allows the device to comprise a side-hole but with a lower level of turbulence (if any), compared with the configuration of Figure 1.
• An example e-cigarette 500 may therefore have an airflow channel 550 with a radius of curvature greater than 5 mm, greater than 10mm, or preferably greater than 15mm, to reduce (or eliminate) turbulence (compared with the configuration of Figure 1), and so help to reduce particle size in the aerosol provided by the device.
• the continuous curve of the airflow channel 550 may only extend part-way between the air inlet 548 and the interface 26.
• the airflow channel 550 may have a smoothly curved portion near air inlet 548, followed by a linear portion near the interface 26 (or conversely, the airflow channel 550 may have a smoothly curved portion near the interface 26, following on from a linear portion near the air inlet 548). More generally, there may be more than one continuous curve and/or more than one linear section in the airflow channel 550.
• a further possibility is that a continuous curve (or multiple such curves) might be approximated by a sequence of short linear sections, whereby the change in orientation of between any two successive linear sections is small, for example, in the range of 1-5 degrees, so as to limit or avoid the introduction of turbulence.
• Figure 6 is a schematic cross-sectional representation of a fourth electronic aerosol provision device 600.
• the components of the e-cigarette 600 of Figure 6 are generally the same as or similar to those described in relation to the Figure 1 (and labelled with like reference numbers), and so these components will not be discussed again.
• the e-cigarettes shown in Figures 1 , 2 and 5 which have fixed airflow channel
• the e-cigarette 600 of Figure 6 has an airflow pathway 650 which may be modified to change the level of turbulence in air inhaled through the device.
• the e-cigarette 600 of Figure 6 includes a facility to adjust the air pathway to control the amount of turbulence within the air pathway, and hence to change the particle size distribution in the aerosol produced by the e-cigarette 600.
• the airflow channel 650 of e-cigarette 600 comprises two sections, a first movable channel section 610 and a second fixed section 610. These two sections are joined by an appropriate coupling or connector 615.
• the first movable airflow channel section 610 therefore extends from the air inlet 648 to the coupling 615, while the second airflow channel section 611 extends from the coupling 615 to the interface 26.
• the movable airflow channel section 610 in effect is able to rotate about the coupling 615 to reposition the air inlet 648.
• the position of the air inlet 648 can be rotated as indicated by the arrows between position A and position A’.
• position A’ the e-cigarette 600 approximates the side-hole configuration shown Figure 1
• position A the e-cigarette 600 approximates the direct linear flow (bottom hole) configuration shown in Figure 2.
• the e-cigarette 600 includes a switch or button 625 for a user to rotate the movable section 610 between positions A and A’.
• This switch 625 may be provided with a suitable mechanical coupling (not shown) to accomplish this rotation of the movable section 610.
• Another possibility is that the rotation of section 610 is performed using electrical power from battery 46 (again under the control of switch or button 625).
• Other actuation mechanisms may be implemented, including direct movement by a user of the movable section 610, in which case button/switch 625 might be omitted.
• e-cigarette 600 has been described above as having two operational positions for movable section 610 corresponding to A and A’ (so that the position shown in Figure 6 is transitional between these two operational positions), other implementations may have one or more additional operational positions intermediate A and A’.
• implementations may allow a continuous adjustment, i.e. the movable section 610 can be located at any desired position intermediate A and A’. It will be appreciated that the portion 621 of the control section housing 32 in which air inlet 648 is formed will be arranged to accommodate the desired range of positions for the air inlet 648.
• the movable channel section 610 is co-aligned with the remainder of the airflow channel 650, in particular fixed section 611 , and so turbulence is minimised.
• the movable channel section 610 is now perpendicular to the remainder of the airflow channel 650 and so turbulence is introduced (or increased). Note that this mechanism allows the level of turbulence to be altered with little or no change to the overall flow rate.
• the size of the air inlet 648 and hence the amount of air inhaled during a puff is substantially maintained regardless of the orientation of the movable channel section 610, however, the particle size distribution for the puff is dependent on (and controlled by) the location setting of the movable channel section 610.
• the orientation of the movable airflow section 610 may be selected by a user interacting with the device through a mechanical switch 625 or similar device such as a wheel or lever to allow the user to tailor the particle size to his/her particular preference.
• this adjustment of the movable airflow section 610 may be performed using the user input button 34 and/or the visual display indicator 44 (in place of, or additionally to, using switch 625).
• the changes to the orientation may be performed very quickly, for example during or between puffs (activations of the heater 68), thereby allowing the user to quickly adjust the particle size to a desired setting.
• the orientation of the movable channel section 610 may be automatically performed by the control circuitry 38, for example, after recognising that a particular cartridge 24 containing a particular e-liquid has been attached to the control unit 22.
• Figure 7 is a schematic cross-sectional representation of a fifth electronic aerosol provision device 700.
• the components of the e-cigarette 700 of Figure 7 are generally the same as or similar to those described in relation to the Figure 1 (and labelled with like reference numbers), and so these components will not be discussed again. More particularly, the e-cigarette 700 of Figure 7 has a configuration which is very similar the e- cigarette 200 of Figure 2, but further includes, like the e-cigarette 600 of Figure 6, a facility to adjust the particle size distribution in the aerosol produced by the e-cigarette 700.
• e-cigarette 700 comprises a fixed airflow pathway 750 extending to air inlet 748 using a direct linear flow configuration, the same as for e-cigarette 200 as shown in Figure 2.
• the e-cigarette 700 further includes a mechanism 715 (shown in schematic form in Figure 7) to alter the configuration of the air pathway 750 so as to modify the relative proportion of laminar and turbulent airflow within the air pathway 750, thereby providing some control over the resulting particle size distribution of the aerosol produced by the e-cigarette 700.
• the mechanism 715 may be operated by a user via button or switch 725 in a similar manner to the use of button 625 in e-cigarette 600 to move the airflow channel section 610.
• the operation of mechanism 715 might be performed using the user input button 34 and/or the visual display indicator 44 (in place of, or additionally to, using switch 725) and/or at least partly automatically by the control circuitry 38.
• mechanism 715 is a shaped diaphragm or aperture which may be changed, for example, between a simple circular shape for the opening to a star shape (or any other more complex shape) for the opening.
• the circular shape introduces relative little turbulence, and hence supports a higher proportion of laminar flow, whereas the more complex (detailed) star-shaped aperture tends to introduce more turbulence by creating more localised variations in pressure, and so leads to a lower proportion of laminar flow.
• the switching between the different aperture shapes may be actuated, for example, using button or switch 725.
• a wall feature such as a baffle, fin or other obstruction (or multiple such items) may be moved into and/or out of the airflow path 750. Inserting such a feature can again lead to more localised pressure variations that promote the formation of turbulence. Accordingly, the level of turbulence (and hence the resulting particle size) may be controlled by adjusting the extent of the insertion or extraction of such obstructions into the airflow channel 750 (e.g. by using button or switch 725). A similar effect could be achieved, for example, by forming or flattening surface texture or other topology on the inside walls of the airflow channel 750.
• mechanism 715 comprises a grill, grating or other similar structure, which may be moved into the airflow path 750 to increase the turbulence of the airflow.
• the grating is formed of fine wire, or similar, such that the grating acts to disrupt and impart turbulence to the airflow, but does not inhibit the airflow rate.
• the grill 715 may be permanently located in the airflow path 750, however, the configuration or some other property (or properties) of the grill might be varied, such as the size of individual openings within the grill, to change the amount of turbulence produced in the airflow.
• a further example of mechanism 715 is an airflow divider, which may be positioned in the airflow path 750 to divide the airflow channel into two or more subchannels. Both the separation of the airflow into the multiple air channels, and then the subsequent recombination of the airflow into a single channel, may lead to the formation of turbulence in the airflow. By varying the proportion of air in each component, the level of turbulence may be controlled.
• the mechanism 715 may not only impact the relative proportion of laminar to turbulent flow, but also the rate of airflow through the e-cigarette for a given pressure drop or strength of inhalation - in effect, increasing the resistance to draw (RTD).
• RTD resistance to draw
• introducing fins or other obstructions into the airflow will generally act as additional RTD resistance to the airflow, in addition to increasing the amount of turbulence. It may be desirable however to allow a user to control the amount of turbulence (and hence particle size) while making little or no change to the RTD (and hence to the overall flow rate).
• One way of achieving this is for the e-cigarette to include a restrictor somewhere along the overall airflow path which is the primary restriction on the airflow through the e-cigarette.
• any changes in RTD caused by different settings of the mechanism 715 will have a relatively low impact on the overall RTD experienced by a user.
• Another approach is for the different settings of the mechanism 715 to be designed to alter the amount of turbulence, but not the overall airflow resistance.
• the sizes of the circular and star-shaped apertures may be arranged so as to provide the same airflow resistance (RTD contribution) for both apertures.
• mechanism 715 is shown in Figure 7 as implemented in the middle of airflow channel 750, it may instead be implemented at the air inlet 748 or the interface 26, or at any suitable location between the air inlet 748 and the interface 26. In some
• the mechanism 715 may comprise multiple components at various locations along the air pathway 750. Alternatively, the mechanism 715 may stretch along a substantial portion (e.g. most or all) of the airflow channel 750 between the air inlet 748 and the interface 26. Furthermore, while the air pathway 750 shown in Figure 7 is substantially linear (a straight line), other implementations may have a curved air pathway, for example, similar to the shape shown in Figure 5 for e-cigarette 500.
• the present approach provides an electronic aerosol provision system or device comprising: an air pathway between an air inlet and an air outlet; and a vaporiser for generating vapour into the air pathway.
• the air pathway between the air inlet and the vaporiser is configured to support laminar airflow.
• a laminar airflow can lead to smaller aerosol particles exiting the electronic aerosol provision system, which in turn can lead to a more favourable user experience. It is believed (without limitation) that a laminar airflow may produce a smaller particle size by reducing particle coagulation and/or by reducing vapour deposition onto particles. Although these physical effects generally happen downstream of the vaporiser, it is difficult to quiesce an airflow within the electronic aerosol provision system which is already turbulent. Accordingly the approach described herein seeks to prevent or reduce the formation of turbulence upstream of the vaporiser, which then helps to prevent or reduce turbulence at (and downstream of) the vaporiser.
• An ideal device might have laminar (non-turbulent) airflow along the entire airflow pathway within the device, from air inlet to air outlet.
• it may be difficult in practice to achieve completely laminar airflow within the device rather the air pathway between the air inlet and the vaporiser may be configured to support substantially (mostly) laminar airflow, for example, having at least 60%, 75%, 85%, 90% or 95% of the airflow through the electronic aerosol provision device being laminar.
• the air pathway may be configured to support (mostly) laminar airflow.
• the air pathway may comprise a linear (straight line) channel between the air inlet and the vaporiser; the absence of sharp bends or angles facilitates laminar flow.
• the air pathway between the air inlet and the vaporiser may include one or more curved portions; each of the one or more curved portions may have a radius of curvature greater than 5 mm and preferably greater than 15mm. Again, the provision of gentle curves rather than sharp bends or angles facilitates laminar flow (and also gives more flexibility in the overall geometry of the device compared with having a straight line airflow).
• Laminar flow along the air pathway between the air inlet and the vaporiser may be further facilitated by ensuring this pathway is substantially free of (i) obstructions, for example, protrusions, grills, narrow apertures, etc., and/or (ii) topology for the walls of the air pathway, for example, surface texturing or other features, that would introduce turbulence into airflow along the air pathway. It will be appreciated that a similar approach may be adopted for the portion of the air pathway downstream of the vaporiser in order to reduce or prevent turbulence in this downstream portion.
• the present approach also provides an electronic aerosol provision system (e.g. such as described above) which comprises a facility to control turbulence within the air pathway.
• the facility provides at least first and second settings, the first setting providing an airflow with a higher proportion of laminar flow relative to turbulence than the second setting.
• the first setting will generally therefore produce an aerosol having a smaller particle size than the second setting.
• the first setting may produce an aerosol having a median particle size (e.g.
• the facility may be operated by a user to control turbulence by selecting an appropriate setting, such as by actuating a button or slider, and/or touching a touch-sensitive input device. In this way, a user can select a setting that provides them with the most satisfactory user experience.
• the facility might be alternatively (or additionally) operated on an automatic basis. For example, the device might detect that a particular cartridge or cartomiser has been installed, and set the facility to provide the most appropriate turbulence level for this cartridge.
• the facility may be implemented in various ways. For example, in some cases the facility might support movement of the airflow pathway such as to introduce or remove a linear channel between the air inlet and the vaporiser. Other ways of changing the turbulence level might be to use a (re)movable airflow divider to divide a portion of the air pathway into two or more channels; a variable aperture (or apertures) along the pathway; and/or one or more structures that can be introduced into or altered within the air pathway. Note that the facility might utilise multiple different approaches for changing the level of turbulence.
• the facility is arranged to maintain a substantially constant airflow through the air pathway as the facility provides different levels of turbulence.
• the facility may use a smooth (circular) aperture to reduce turbulence, or a more angled aperture, e.g. a star, to increase turbulence.
• the overall size of each aperture may then be configured such that the differently shaped apertures provide the same resistance to draw (and hence overall airflow). In this way, a user is able to adjust the particle size of the aerosol without also changing other parameters of the device, such as resistance to draw, which supports easier device management for a user.

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