WO2023083645A1 - Aerosol generating systems - Google Patents

Abstract

A handheld aerosol generating system comprises a cartridge (4) removably attached to an aerosol generating device (2), the cartridge (4) supplying an aerosol generating liquid (31) from a reservoir (16) to mixing chamber (14) along a fluid flow path (32). A vent (15) maintains the interior of the reservoir (16) substantially at ambient pressure during use. The system is primed before use by introducing air at above ambient pressure into the reservoir (16) to drive movement of fluid along the fluid flow path (32) and expel any air that entered the fluid flow path (32) when the cartridge (4) was attached. The priming means (30) may introduce the air through the vent (15) or through a dedicated port (52), optionally via a three-way rotary valve (60). A liquid jet head (82) may be used to deliver aerosol generating liquid (31) into the mixing chamber (14). The device (2) may comprise a movable portion (78) that can be retracted to expose the liquid jet head (82) to view during priming. The movable portion (78) may then wipe the liquid jet head (82) clean as it slides back into place.

Description

TITLE

Aerosol generating systems

DESCRIPTION

Technical Field

The present disclosure relates generally to handheld aerosol generating systems, which are configured to convert a liquid into an aerosol for inhalation by a user of the system. More specifically, it relates to such aerosol generating systems, in which the aerosol is generated in a device and the aerosol generating liquid is supplied from a cartridge that is removably coupled to the device.

Technical Background

The term aerosol generating system (or more commonly electronic cigarette or e-cigarette) refers to handheld electronic apparatus that is intended to simulate the feeling or experience of smoking tobacco in a traditional cigarette. Electronic cigarettes typically work by heating an aerosol generating liquid to generate a vapour that cools and condenses to form an aerosol which is then inhaled by the user. Accordingly, using e-cigarettes is also sometimes referred to as “vaping”. The aerosol generating liquid usually comprises nicotine, propylene glycol, glycerine and flavourings.

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.

Typical e-cigarettes generate the aerosol from liquid stored in a capsule, tank or reservoir. When a user operates the e-cigarette, liquid from the reservoir is transported along a fluid flow path to an aerosol generating unit. The aerosol generating unit comprises a liquid transfer element, e.g. a cotton wick or a permeable ceramic block, to control the rate at which the liquid enters a mixing chamber. Inside the mixing chamber, the liquid is heated by a heating element to produce a vapour, which mixes with air drawn into the device by the user. The vapour then cools and condenses to form an aerosol that can be inhaled by the user.

To facilitate the ease of use of e-cigarettes, the reservoir of aerosol generating liquid is often housed in a removable cartridge, which can be replaced when its supply of liquid is exhausted or when the user wishes to change to a different type or flavour of liquid. Such cartridges may be disposable, i.e. not intended to be capable of reuse after the supply of liquid in the reservoir has been exhausted. Alternatively, they may be reusable, being provided with means allowing the reservoir to be refilled with a new supply of liquid.

When a cartridge is replaced, the conduit that forms the fluid flow path from the reservoir to the mixing chamber is necessarily interrupted, which allows air to enter the fluid flow path. This can cause a problem with the use of the new, replacement cartridge because a bubble of air in the fluid flow path will at best cause a gap in the flow of aerosol generating liquid into the mixing chamber and may at worst obstruct the supply of aerosol generating liquid from the reservoir. A similar and potentially greater problem may arise when the aerosol generating system is first used because such systems are typically shipped and supplied without being loaded with a cartridge, whereby the fluid flow path may initially be full of air. Air bubbles or airlocks in the fluid flow path may be a particular problem for systems that rely on microelectromechanical systems (MEMS) or microfluidics technologies for transport of the liquid through very narrow conduits. In this specification, “fluid” is used to describe a liquid, a gas or a mixture of a liquid with a gas.

By a “handheld” aerosol generating system is meant one that is small enough and light enough to be held comfortably in one hand during use. Because of their small size - typically no more than 15cm long or 6cm wide - handheld aerosol generating systems are limited in battery power and in space to accommodate complex components.

Summary of the invention

The invention provides a handheld vapour generating system comprising: an aerosol generating device containing a mixing chamber, in which an aerosol can be generated from an aerosol generating liquid; a cartridge removably attached to the aerosol generating device, the cartridge comprising a reservoir that contains a supply of the aerosol generating liquid; a fluid flow path for conducting the aerosol generating liquid in a forward direction from the reservoir towards the mixing chamber when the system is being used to generate an aerosol; a vent for admitting air into the reservoir to replace aerosol generating liquid that is conducted away from the cartridge when the system is being used to generate an aerosol and thereby to maintain the reservoir substantially at ambient pressure when the system is being used to generate an aerosol; and priming means configured to introduce air at above ambient pressure into the reservoir for driving movement of fluid in the forward direction along the fluid flow path to prime the system when the system is not being used to generate an aerosol.

The invention further provides a method of operating a handheld aerosol generating system, the system comprising: an aerosol generating device containing a mixing chamber, in which an aerosol can be generated from an aerosol generating liquid; a cartridge removably attached to the aerosol generating device, the cartridge comprising a reservoir that contains a supply of the aerosol generating liquid; and a vent; the method comprising: when the system is not being used to generate an aerosol, operating a priming means to introduce air at above ambient pressure into the reservoir, thereby to drive movement of fluid along a fluid flow path in a forward direction from the reservoir towards the mixing chamber; and when the system is being used to generate an aerosol, admitting air into the reservoir to replace aerosol generating liquid that is conducted away from the cartridge, thereby to maintain the reservoir substantially at ambient pressure.

The fluid driven along the fluid flow path by the priming means may comprise the aerosol generating liquid, air or a mixture of the two. The priming means and method according to the invention can therefore be used to “prime” the system by expelling air from the fluid flow path before a new cartridge is used or at any other time if it is suspected that air has entered the path, for example if a seal has been broken or after a long period of non-use. The vent allows the air pressure inside the reservoir to remain substantially equal to the ambient atmospheric pressure so that there is no pressure difference between the mixing chamber and the reservoir to resist the transport of liquid along the fluid flow path during use. Inevitably, the pressure inside the reservoir will fall slightly below ambient pressure as liquid is removed and the air replacing it takes a certain amount of time to bleed in through the vent, but the vent can be designed with a cross-section such that the temporary pressure difference is not substantial enough to impede the practical effectiveness of the system. The vent also serves a purpose when the system is not in use, namely, to equalize the internal and external pressures, which might otherwise diverge because of changes in the ambient temperature or pressure and risk causing leakage.

The priming means may be configured to introduce the air at above ambient pressure into the reservoir through the vent. The vent is normally used to admit air when the system is being used to generate an aerosol and, by using the same vent to introduce air to prime the system when it is not being used to generate an aerosol, this aspect of the invention avoids the need to create a second aperture in the reservoir. Such a system preferably further comprises means for moving the priming means to engage or disengage with the vent, in order that the priming means does not obstruct the vent from performing its normal function of admitting air while the system is being used to generate aerosol.

Alternatively, the cartridge may further comprise a port distinct from the vent, the priming means being configured to introduce the air at above ambient pressure into the reservoir through the port, instead of through the vent. This provides the advantage that the vent and the port may be designed independently in the best way to perform their respective functions, instead of being combined to perform a dual function. For example, the vent required to admit a trickle of air as aerosol generating liquid is gradually drawn out of the cartridge during normal use of the system may be very small, whereas the port may be larger to permit air to flow into the reservoir at a greater rate during the priming process. The priming means preferably further comprises means for sealing the vent while air at above ambient pressure is introduced into the reservoir through the port. This avoids the risk that the elevated pressure created inside the cartridge by the priming means might cause aerosol generating liquid to leak out of the vent.

In a further alternative, the aerosol generating device further comprises an air inlet in communication with the reservoir; and the priming means further comprises a three- way valve that can selectively couple the air inlet to the vent to admit air at ambient pressure when the system is being used to generate an aerosol or couple the air inlet to the port to introduce the air at above ambient pressure into the reservoir when the system is being primed. The air inlet provides a single aperture for air to enter the reservoir, while the three-way valve is easy to operate, e.g. under automatic control, to select whether that air is to be supplied from the atmosphere via the vent during normal use of the system or supplied from the priming means at elevated pressure via the port during priming of the system.

Such a handheld aerosol generating system may further comprise a cyclically operating pump in communication with the port, wherein the three-way valve can further selectively couple the port to the vent to supply air to the pump during each operating cycle of the pump. A “cyclically operating pump” includes pumping means that operate in a reciprocating or repetitive manner, such as a bellows, and that work by periodically pumping air out of a pumping chamber, which then needs to be refilled with new air. The third position of the three-way valve in accordance with this aspect of the invention permits atmospheric air to enter through the vent and to flow through the valve to supply the pump, while being isolated from the reservoir.

The three-way valve is preferably a rotary valve. A rotary valve may be compact and efficient. It allows the possibility of rotating the valve in only one direction to select any of the available couplings. The priming means may comprise a manual pump for generating the air at above ambient pressure.

The handheld aerosol generating system according to the invention preferably comprises a liquid transfer element for introducing the aerosol generating liquid from the fluid flow path into the mixing chamber. The liquid transfer element may be, for example, a wick or a permeable ceramic block. In preferred embodiments of the invention, the liquid transfer element is a liquid jet head, which works in a similar way to ink-jet heads used in printing to expel droplets of the aerosol generating liquid into the mixing chamber. One type of liquid jet head is a thermal jet head, in which one or more heating elements superheat a very small volume (less than 1%) of the aerosol generating liquid to vaporize it and push a drop of the remaining liquid drop out of the jet head and into the air in the mixing chamber. An alternative to a thermal jet head is a piezoelectric jet head, which uses a piezoelectric element to generate pressure pulses in the aerosol generating liquid and push drops of it out of the jet head and into the air in the mixing chamber.

Liquid jet heads have the advantage that the delivery of the vapour generating liquid into the mixing chamber can be carefully controlled. They may also enable the system to operate at a lower temperature and therefore with a lower energy requirement because they do not depend on heat to vaporize at least the majority of the liquid. Because liquid jet heads generate an aerosol directly, the size of droplets in the aerosol can be more carefully controlled and more uniform compared with traditional aerosol generating devices that form an aerosol indirectly by condensing vapour. Traditional devices may need to be designed to promote the condensation of vapour, e.g. by providing a passage downstream from the mixing chamber in which this can occur, but this is not necessary with jet head technology, thereby removing a constraint on the design of such devices. Traditional devices can also suffer from vapour condensing preferentially on internal surfaces of the device, where it collects into liquid that can flow out of the device and cause leakage. Because jet head technologies inject droplets directly into the air, this problem may be avoided. In some embodiments of the invention, the aerosol generating device further comprises a movable portion that is capable of movement to expose the liquid transfer element to view while the priming means is in use. This allows a user of the device to observe when the priming process has continued sufficiently for aerosol generating liquid to be expelled from the liquid transfer element. The user can then be confident that air has been eliminated from the fluid flow path and the priming process can be ended. The movable portion may form a wall of the mixing chamber. It may carry a mouthpiece of the device.

The movable portion of the aerosol generating device may be capable of further movement to conceal the liquid transfer element from view while the priming means is not in use; the movement to conceal the liquid transfer element being generally parallel to a surface of the liquid transfer element; and the movable portion comprising means for wiping aerosol generating liquid from the surface of the liquid transfer element during the movement to conceal the liquid transfer element. If droplets of the aerosol generating liquid have appeared on the surface of the liquid transfer element during the priming process, they may not evaporate because the mixing chamber is not being heated and/or there is no airflow through the chamber at that time. This results in a risk that such droplets, in a liquid or a dried state, could interfere with the transfer of further liquid during subsequent normal use of the system. Through movement of the movable portion parallel to the surface of the liquid transfer element after priming is complete, the surface can conveniently be wiped clean of liquid before the system is used to generate an aerosol.

The drawings

Figure 1 is a perspective view of an example of a handheld vapour generating system of a kind in which the invention may be used.

Figure 2 is a view, in longitudinal section, showing the fluid flow path from a reservoir and generally indicating a preferred location of a priming means according to the present invention.

Figure 3 is a highly schematic diagram of a first embodiment of the invention. Figure 4 is a highly schematic diagram of a second embodiment of the invention.

Figures 5a to 5f show a possible sequence of operation of a first example of a rotary valve during the use of an embodiment of the invention.

Figures 6a to 6c show steps in the operation of a second example of a rotary valve during the use of an embodiment of the invention.

Figures 7a to 7c show steps in the operation of a third example of a rotary valve during the use of an embodiment of the invention.

Figure 8 is a perspective view of the handheld vapour generating system of Figure 1, in which the mouthpiece has been retracted.

Figure 1 illustrates a handheld vapour generating system, comprising an aerosol generating device 2 and a replaceable cartridge 4 that is removably received in the aerosol generating device 2. The device 2 is enclosed by a housing 6. A door 8 in the housing 6 may be opened to permit access to the interior of the housing 6 for the insertion or removal of the cartridge 4. The cartridge 4 provides a supply of an aerosol generating liquid, which can be used by the device 2 to generate an aerosol. A proximal end of the device 2 comprises a mouthpiece 10, through which a user of the system can inhale the aerosol generated by the system. A distal end 12 of the housing 6 contains a battery (not visible in the drawing) to provide a power supply for the system and electronic circuits (not visible in the drawing) for controlling the operation of the system.

The configuration and operation of the system during normal use to generate an aerosol may be conventional. They do not form part of the present invention and are not described in any detail here. The system may take forms that are very different from that illustrated in Figure 1, provided it can accommodate removable cartridges 4, which are coupled via a fluid flow path to a mixing chamber in the aerosol generating device 2.

Figure 2 is a longitudinal section through the replaceable cartridge 4, which illustrates a fluid flow path for supplying the aerosol generating liquid from the cartridge 4 to a mixing chamber 14 of the aerosol generating device. The housing 6, mouthpiece 10 and other components of the aerosol generating device 2 are not shown in Figure 2. It will be understood that the mixing chamber 14 shown as an open space at the top of Figure 2 will in reality be enclosed by one or more of those components to form a space that is substantially sealed apart from an air inlet and an air outlet in communication with the mouthpiece 10.

In the cartridge 4 illustrated in Figure 2, the aerosol generating liquid is supplied from two independent reservoirs 16, although this is not essential for the invention. In alternative embodiments of the invention, the cartridge 4 may comprise a single reservoir or more than two reservoirs and, if it comprises a plurality of reservoirs, they may be interconnected rather than being independent. In the illustrated embodiment, a separate fluid flow path is provided from each reservoir 16 to a common mixing chamber 14. As the quantity of liquid in each reservoir 16 is depleted, ambient air is allowed to flow into the reservoir 16 to replace the volume of liquid lost, as indicated schematically by arrows 17. The air enters the reservoir 16 via a vent 15, which is not visible in the plane of Figure 2. The vent 15 may comprise a “micropore” or “pinhole” opening that is sufficiently small to allow air to enter, while aerosol generating liquid is prevented from leaking out of the opening by surface tension.

A first portion of each fluid flow path is formed by a first tube 18, which has an inlet 20 inside the reservoir 16, preferably close to its distal end, and extends longitudinally through the reservoir 16 to emerge from its proximal end. A second portion of the fluid flow path is formed by a second tube 22, which extends between the cartridge 4 and the aerosol generating device 2. In use, the second tube 22 is in fluid communication with first tube 18 and conducts aerosol generating liquid from the cartridge 4 into the aerosol generating device 2. Accordingly, when the cartridge 4 is replaced, the second tube 22 needs to be detached from either the cartridge 4 or the aerosol generating device 2. Preferably, the second tube 22 is anchored to the aerosol generating device 2, whereby, when the cartridge 4 is replaced, the second tube 22 becomes detached from the cartridge 4. Prior to use, a new cartridge 4 may be sealed by a septum 23 across the proximal end of the reservoir 16, which prevents leakage of the aerosol generating liquid from the cartridge 4 and prevents contamination of the aerosol generating liquid from the environment. In that case, the second tube 22 may take the form of a rigid, hollow needle, which is anchored to the aerosol generating device 2 and pierces the septum 23 of a new cartridge 4 when it is installed in the aerosol generating device 2 to establish fluid communication between the first and second tubes 18,22.

Sealing means (which may include the septum 23, if present) are provided around the second tube 22 to prevent air entering the fluid flow path from the gap between the aerosol generating device 2 and the cartridge 4.

A third portion of each fluid flow path is formed by a conduit 24 within the aerosol generating device 2. In the illustrated embodiment, the conduit 24 is formed as a channel through a solid body of the aerosol generating device 2 but in alternative embodiments of the invention, part or all of the conduit 24 could be formed as a separate tubular component. In the illustrated embodiment, each conduit 24 includes a substantially transverse portion to bring the two conduits 24 from the respective reservoirs 16 closer together near the mixing chamber 14 but that is a mere design feature of this particular embodiment and is not essential to the invention. In use, the conduit 24 is in fluid communication with the second tube 22 so that the aerosol generating liquid travels along the fluid flow path in series through the first tube 18, the second tube 22 and the conduit 24, as indicated by arrows 25.

A proximal end of the conduit 24 is coupled to a liquid transfer element 26, which receives liquid supplied via the fluid flow path and transfers it into the mixing chamber 14 at a controlled rate. Ideally, the rate of transfer should match the rate at which the liquid is converted into an aerosol and is consumed by the user of the system drawing air through the mixing chamber 14 to carry the aerosol away. The rate of transfer may in practice determine the rate at which the liquid is converted into an aerosol and/or it may respond to the demand for aerosol to be supplied. The liquid transfer element 26 may comprise, for example, a wick of cotton or other fibrous material, which absorbs liquid from the fluid flow path and is exposed to the interior of the mixing chamber 14, whereby the liquid may evaporate from the wick in the elevated temperature of the mixing chamber 14. Another passive form of liquid transfer element 26 comprises a permeable ceramic block, which similarly absorbs liquid from the fluid flow path and is exposed to the interior of the mixing chamber 14, whereby the liquid may evaporate from an exposed surface of the block. Another alternative form of liquid transfer element 26 comprises a liquid jet head, similar to that used in an ink-jet printer, which receives a supply of the aerosol generating liquid from the fluid flow path and actively ejects controlled quantities of the liquid as minute droplets 28 into the mixing chamber 14.

When a cartridge 4 is removed from the aerosol generating device 2, the fluid flow path is interrupted, for example by the second tube 22 being withdrawn from the cartridge 4. Accordingly, when a new cartridge 4 is installed in the device 2 (including the first time a cartridge 4 is installed in it) there is a strong likelihood that air will have entered the fluid flow path and will become trapped in it. As previously mentioned, air bubbles or airlocks in the fluid flow path may cause problems with the supply of aerosol generating liquid therethrough, particularly in the case of narrow conduits that may be used with liquid transfer elements in the form of liquid jet heads. In accordance with the present invention, the aerosol generating system comprises priming means 30 configured to introduce air at above ambient pressure into the reservoirs 16 for driving movement of fluid in the forward direction along the fluid flow path when the system is not being used to generate an aerosol. The priming means 30 may take various forms, to be described below, so in Figure 2 it is indicated purely schematically as a block.

The priming means 30 is preferably provided as part of the aerosol generating device 2. It would alternatively be possible to provide the priming means 30 in the cartridge 4 but that would increase the complexity and cost of the cartridge 4, which is preferably a relatively cheap, consumable article (even if it is capable of being refilled). By increasing air pressure behind the aerosol generating liquid in the reservoir 16, the priming means 30 drives a small quantity of the liquid into the first tube 18, pushing whatever combination of aerosol generating liquid and air may be ahead of it in the fluid flow path forwards towards the mixing chamber 14. In the simplest arrangement, the fluid mixture passes through the liquid transfer element 26 to be discharged into the mixing chamber 14. The process continues until there can be reasonable confidence that no air remains in the fluid flow path. Particularly on first use of the device 2, this might entail expelling fluid - principally air, in this case - from the entire volume of the fluid flow path. However, particularly during replacement of a cartridge 4 in a device 2 that has previously been used, it might be sufficient to expel fluid only from the portion of the fluid flow path that lies downstream from a point close to where the path has been interrupted and air is likely to have been admitted.

If the expulsion of a quantity of unvaporized liquid into the mixing chamber 14 is likely to cause problems during subsequent use, or if the nature of the liquid transfer element 26 makes it unsuitable for liquid to be pumped through it at the required rate, then it may be possible to provide means (not illustrated) for diverting the pumped liquid into a sump instead of into the mixing chamber 14. For example, a valve could be opened when the priming means 30 is in operation. If the priming means 30 is operated electronically, then the operation of the valve could similarly be under electronic control. Alternatively, given that the priming means 30 will create a higher fluid pressure in the fluid flow path during priming of the system than the pressure during normal use, it may be possible to provide a valve near the downstream end of the fluid flow path, which opens selectively during priming in response to that increased pressure to discharge the pumped mixture of air and liquid.

Figure 3 schematically shows a first embodiment of the invention, in which the priming means 30 is a manually operated pump, which introduces air at elevated pressure into the vent 15. The priming means 30 forms part of the device 2 and is positioned adjacent to the cartridge 4 that contains the reservoir 6 of aerosol generating liquid 31. During normal use of the aerosol generating system, the priming means 30 adopts the rest position shown in Figure 3, where the vent 15 remains open to admit a trickle of air from the atmosphere to replace the volume of aerosol generating liquid 31 that is drawn out of the reservoir 16 along the flow path 32. When a new cartridge 4 has been inserted into the device 2 - including on first use of the device 2 - the priming means 30 may be actuated by a user applying pressure with their finger or thumb 34, as indicated by the arrow 36. This first causes the priming means 30 to rotate about a pivot 38, as indicated by the arrow 40, to bring a nozzle 41 of the head 42 of the priming means 30 into contact with the opening of the vent 15. The opening of the vent 15 or the nozzle 41 (or both) may be provided with a seal 44 to create an airtight engagement between them.

Further pressure applied in the direction of the arrow 36 causes compression of a bellows 46 on the head 42 of the priming means 30, which expels air at elevated pressure through the nozzle 41 and into the vent 15 of the reservoir 16. The elevated air pressure created by the bellows 46 causes a one-way valve 48 in the head 42 to open and allow the air to flow therethrough towards the vent 15. Preferably, as shown, the vent 15 opens into a void 49 above the aerosol generating liquid 31 in the reservoir 16, but this will depend on the orientation of the system during the priming process. Even if the vent 15 opens directly into the volume of liquid 31 in the reservoir 16, introducing air through the vent 15 will increase the pressure in the reservoir 16 and cause some of the liquid 31 to be displaced therefrom, along the fluid flow path 32.

When the bellows 46 has been fully compressed, pressure 36 from the thumb 34 may be released to allow it to expand again and re-fill with air. The thumb 34 may be completely removed from the bellows 46 or may be tilted to one side to allow air to enter through an aperture 50 in the end of the bellows 46 that was previously sealed by the thumb 34. Alternatively, the bellows 46 may be provided with a further one-way valve (not illustrated) to allow atmospheric air to enter as the bellows 46 expands, while remaining in contact with the thumb 34. The nozzle 41 of the priming means 30 remains in contact with the vent 15 as the bellows 46 expands but the one-way valve 48 inside the head 42 prevents air in the reservoir 16, which is now at elevated pressure, escaping via the vent 15. When the bellows 46 has fully expanded, further relaxation of pressure from the thumb 34 allows the priming means 30 to rotate about the pivot 38 and disengage from the vent 15. A linear or rotary spring (not illustrated) may be provided to urge this disengagement when pressure is released.

Depending on the capacity of the bellows 46 and the volume of fluid that it is desired to displace from the fluid flow path 32, the process may be repeated as many times as necessary, until there can be reasonable confidence that no air remains in the fluid flow path 32. It is not necessary to disengage the nozzle 41 from the vent 15 on each cycle but only when the priming process is complete.

It will be understood that Figure 3 is highly schematic and that the priming means 30 may adopt various configurations and be integrated into the housing 6 of the device in various ways. For example, it is not necessary that the engagement and disengagement between the nozzle 41 and the vent 15 should be achieved by rotation of the head 42 about a pivot 38. Instead, means (not illustrated) could be provided to allow the head 42 to slide towards and away from the vent 15. The one-way valve 48 need not be a ball valve as illustrated but could use a flap or any other suitable design.

The size of the vent 15 in known reservoirs 16 may be very small because only a slow trickle of air through the vent 15 is required to replace the volume of aerosol generating liquid 31 drawn along the fluid flow path 32 during normal use of the system. The size of the vent 15 may need to be increased in order to use it with a priming means 30 according to the invention, as shown in Figure 3, if the priming process is to displace all or a substantial part of the volume of fluid in the fluid flow path 32 within a reasonable time. Increasing the size of the vent 15 increases the risk that aerosol generating liquid 31 may leak through it, causing wastage of the liquid and possible contamination of the surroundings or damage to other parts of the aerosol generating system. In such a case, the open vent 15 may need to be provided with a one-way valve (not illustrated), which allows air to enter the reservoir 16 but does not allow fluid to exit through the valve. If the vent 15 comprises such a one-way valve then it may not be necessary for the priming means 30 to comprise the one-way valve 48 to serve a similar purpose.

Figure 4 schematically shows a second embodiment of the invention, which is similar to that in Figure 3, except that the priming means 30 does not introduce air into the reservoir 16 via the vent 15 but via a separate port 52. This provides the advantage that the vent 15 and the port 52 may be independently designed in the best way to serve their respective functions, instead of being combined to serve a dual function. For example, the vent 15 may retain a size sufficiently small to minimize the risk of leakage of aerosol generating liquid 31 therefrom, while the port 52 may be larger to accommodate a greater flow of air into the reservoir 16 during the priming process. In addition, the priming means 30 may be permanently coupled to the port 52, so that the pivot 38 of Figure 3, which enables the head 42 of the priming means 30 to engage or disengage with the vent 15, can be omitted. In other respects, the priming means 30 of Figure 4 is very similar to that of Figure 3 and will not be described in detail. The thumb or finger 34 of a user compresses the bellows 46 to force air at elevated pressure into the reservoir 16 via the port 52 and a one-way valve 48 in the head 42 of the priming means 30 opens to permit the air to flow therethrough. When pressure from the thumb 34 is released, the bellows 46 expands and refills, while the one-way valve 48 prevents air at elevated pressure from flowing back out of the port 52.

Because of the elevated air pressure in the reservoir 16 when the priming means of Figure 4 is actuated to introduce air through the port 52, there is a risk that air (and perhaps aerosol generating liquid 31) may be caused to bleed out of the separate vent 15. To avoid that, the priming means 30 may include a cap 54 that is applied to close the vent 15 temporarily when the priming means 30 are actuated. Figure d schematically shows the cap 54 coupled to the free end of the bellows 46 via a spring 56. As soon as the user applies pressure 36 to the bellows 46 and they begin to compress, the cap 54 comes into contact with the vent 15 to close it so that air expelled from the bellows 46 into the reservoir 16 cannot leave again via the vent 15. Further movement of the bellows 46 is accommodated by the spring 56, which thereby holds the cap 54 more firmly against the vent 15 as the air pressure in the reservoir 16 increases.

In alternative embodiments of the invention, the manual pump based on bellows 46 in Figures 3 and 4 could be replaced by an electronic pump (not illustrated). Such an electronic pump could be manually operated by the user pushing a button, for example. Alternatively, it could be under the automatic control of circuitry built into the aerosol generating device 2, which may be programmed to actuate the priming means 30 when it is used for the first time after the installation of a cartridge 4 or after a long period without use. If an electronic pump were used in the embodiment of Figure 4, then an electromagnetic actuator, such as a solenoid, could be used to close the vent 15 when the pump was actuated.

It is also possible that in some embodiments of the invention, instead of a manually or electronically operated pump to introduce air from the atmosphere into the reservoir at elevated pressure, the high pressure air could be delivered from a store of compressed air or another gas (not illustrated) that is installed in the device 2. A valve would be opened manually or preferably electronically to admit air from the compressed source into the reservoir 16 in order to prime the system.

Figure 5 shows an example of a three-way rotary valve 60 that may be used to interface and control airflow in an appropriate manner between a source of pressurized air, a vent and the reservoir in accordance with embodiments of the invention. The rotary valve 60 comprises a vent port 62 that may be coupled to the atmosphere, for example via a micropore (not illustrated) that can admit a trickle of air into the reservoir 16 to replace the volume of aerosol generating liquid 31 that is drawn out of the reservoir 16 during normal use of the aerosol generating system. The rotary valve 60 further comprises a pump port 63 that may be coupled to a source of air (or another gas) at elevated pressure. As described above, the source of air at elevated pressure may be a manual pump like those shown schematically in Figures 3 and 4, an electronic pump or a store of compressed air. Finally, the rotary valve 60 comprises a reservoir port 64, which may be coupled to the reservoir 16 (not illustrated in Figure 5) to serve as an air inlet - preferably the sole air inlet - for the reservoir. The vent port 62, pump port 63 and reservoir port 64 are arranged at 90° intervals around a rim 66 of the rotary valve 60.

The rotary valve 60 further comprises a hub 68 with a central manifold 70, which is in fluid communication with radiating first, second, third, fourth and fifth arms 71,72,73,74,75. The first, second and third arms 71,72,73 are arranged at 90° intervals to form a T-shaped configuration in one half of the hub 68. The fourth and fifth arms 74,75 are arranged at 90° to one another, being offset by 45° from the third and first arms respectively, to form an L-shaped configuration in the other half of the hub 68. By rotating the hub 68 relative to the rim 66, the first to fifth arms 71-75 can selectively be brought into communication with the vent port 62, pump port 63 and reservoir port 64 to couple certain of those ports together via the central manifold 70, as will now be described. Air cannot flow through the radiating arms when they are not in communication with one of the ports 62,63,64. As illustrated, the rotary valve 60 does not control the direction of airflow between the ports 62,63,64 but any necessary one-way valves could be incorporated into the ports 62,63,64 of the rotary valve 60 if required. As described in more detail below, in different states of the rotary valve 60 air flows through the pump port 63 in different directions.

In Figures 5a to 5f, straight arrows with solid heads show the permitted flow of air through the rotary valve 60, while curved arrows with open heads show the rotation of the hub 68 in each Figure relative to the preceding one.

Figure 5a shows the position of the rotary valve 60 during normal use of the aerosol generating system. The vent port 62 is coupled to the reservoir port 64 via the third arm 73 and the first arm 71, while the pump port 63 is isolated. Thereby air from the vent port 62 is able to bleed into the reservoir 16 as aerosol generating liquid 31 is consumed during use of the aerosol generating system.

When a priming step is initiated, the hub 68 is turned clockwise through 45°, as shown in Figure 5b. Thereby, the pump port 63 is coupled to the reservoir port 64 via the fourth arm 74 and the fifth arm 75, while the vent port 62 is isolated. Accordingly, the pump is able to supply air at elevated pressure into the reservoir 16 to prime the system by driving aerosol generating liquid 31 along the flow path 32 to expel any air therefrom.

If the pump coupled to the pump port 63 is a bellows 46 or similar device that operates in a cyclical manner then, at the end of each cycle, the bellows 46 needs to be refilled with air to be delivered in the following cycle of the priming process. To achieve this, the hub 68 is turned further clockwise through 45°, as shown in Figure 5c. Thereby, the vent port 62 is coupled to the pump port 63 via the second arm 72 and the third arm 73, while the reservoir port 64 is isolated. Accordingly, the pump is able to receive air from the atmosphere through the vent port 62 as the bellows 46 expand.

Thereafter, a further priming cycle may be carried out, for which purpose the hub 68 is rotated back through 45°, as shown in Figure 5d. It is now in the same position as Figure 5b so air can be pumped from the pump port 63 to the reservoir port 64 as previously described. The cycle of Figures 5c and 5d can repeated as often as necessary until priming of the system is complete. Then the hub 68 is rotated 45° clockwise once more, as shown in Figure 5e. It is now in the same position as Figure 5c so the pump is able to receive air through the vent port 62 to allow the bellows 46 to expand and return to its initial condition, ready for future use.

When priming of the system is complete, the hub 68 is rotated 90° anti-clockwise from the position of Figure 5e, as shown in Figure 5f. It is now back in the same position as Figure 5a so the aerosol generating system can be used normally, with air flowing from the vent port 62 through the rotary valve 60 to enter the reservoir 16.

The sequence of rotating the rotary valve 60 forwards and backwards during successive cycles of the priming process may be too complex or too laborious for a user of the aerosol generating system to carry out manually so it is preferably carried out automatically, using a small electric motor (not illustrated) to rotate the hub 68 between the required positions. A stepper motor would be suitable for this purpose, being designed to rotate at low or high speed, but also to stop at a precise angle of rotation.

It will be understood that the rotary valve 60 may take different forms from that illustrated in Figure 5. In particular, the ports 62,63,64 may be arranged differently around the rim 66, with the radiating arms 71-73 being disposed at different angles in order to bring them into selective communication. The arrangement of ports 62,63,64 and arms 71-75 in the rotary valve 60 of Figure 5 has the possible advantages that the ports 62,63,64 are disposed at 90° to one another, with the vent port 62 being opposite the reservoir port 64; and that the hub 68 needs to be rotated through an angular range of only 90°, which may reduce its drain on the power supply in the device 2. It may be noted that there are only three distinct angular positions of the hub 68 in Figure 5, as shown respectively in Figures 5a, 5b and 5c. Between them, they provide communication between each of the three possible pairs of ports, namely between the vent port 62 and the reservoir port 64 in Figure 5a; between the pump port 63 and the reservoir port 64 in Figure 5b; and between the vent port 62 and the pump port 63 in Figure 5c.

This suggests a possible variant of the rotary valve 60, as shown in Figure 6. The vent port 62, pump port 63 and reservoir port 64 are arranged around the rim 66 of the rotary valve 60 in the same configuration as in Figure 5. However, in this embodiment of the invention, the fourth arm 74 and the fifth arm 75 are omitted, which simplifies the construction of the hub 68 at the expense of requiring it to rotate through greater angles.

Figures 6a, 6b and 6c correspond respectively to Figures 5a, 5b and 5c and will be described only briefly. Between them they show the three possible configurations of the rotary valve 60 and the descriptions analogous to Figures 5d, 5e and 5f will not be repeated.

Figure 6a shows the position of the rotary hub 68 during normal use of the aerosol generating system. The vent port 62 is coupled to the reservoir port 64 via the third arm 73 and the first arm 71, while the pump port 63 is isolated. Thereby air from the vent 15 is able to bleed into the reservoir 16 as aerosol generating liquid 31 is consumed during use of the aerosol generating system.

When a priming step is initiated, the hub 68 is turned anticlockwise through 90°, as shown in Figure 6b. Thereby, the pump port 63 is coupled to the reservoir port 64 via the first arm 71 and the second arm 72, while the vent port 62 is isolated. Accordingly, the pump is able to supply air at elevated pressure into the reservoir 16 to prime the system by driving aerosol generating liquid 31 along the flow path 32 to expel any air therefrom. To refill the bellows 46 of the pump (not shown in Figure 6), the hub 68 is turned in either direction through 180°, as shown in Figure 6c. Thereby, the vent port 62 is coupled to the pump port 63 via the second arm 72 and the third arm 73, while the reservoir port 64 is isolated. Accordingly, the pump is able to receive air from the atmosphere through the vent port 62 as the bellows 46 expand.

Figure 7 shows a further possible variant of the rotary valve 60. In this embodiment of the invention, the vent port 62, pump port 63 and reservoir port 64 are arranged around the rim 66 of the rotary valve 60 at equal angular intervals of 120°. This further simplifies the construction of the hub 68 by allowing the third arm 73 to be omitted but at the cost that the vent port 62 is no longer positioned opposite the reservoir port 64.

Figures 7a, 7b and 7c correspond respectively to Figures 6a, 6b and 6c and will be described only briefly. Between them they show the three possible configurations of the rotary valve 60 and the descriptions analogous to Figures 5d, 5e and 5f will not be repeated.

Figure 7a shows the position of the rotary hub 68 during normal use of the aerosol generating system. The vent port 62 is coupled to the reservoir port 64 via the second arm 72 and the first arm 71, while the pump port 63 is isolated. Thereby air from the vent port 62 is able to bleed into the reservoir 16 as aerosol generating liquid 31 is consumed during use of the aerosol generating system.

When a priming step is initiated, the hub 68 is turned anticlockwise through 120°, as shown in Figure 7b. Thereby, the pump port 63 is coupled to the reservoir port 64 via the first arm 71 and the second arm 72, while the vent port 62 is isolated. Accordingly, the pump is able to supply air at elevated pressure into the reservoir 16 to prime the system by driving aerosol generating liquid 31 along the flow path 32 to expel any air therefrom.

To refill the bellows 46 of the pump (not shown in Figure 7), the hub 68 is turned further anticlockwise through 120°, as shown in Figure 7c. Thereby, the vent port 62 is coupled to the pump port 63 via the first arm 71 and the second arm 72, while the reservoir port 64 is isolated. Accordingly, the pump is able to receive air from the atmosphere through the vent 15 as the bellows 46 expand.

It has been stated that the process of priming the aerosol generating system should continue until there can be reasonable confidence that no air remains in the fluid flow path 32. Particularly on first use of the system, it may be expected that air initially fills the entire volume of the fluid flow path 32 so the priming process will need to transport a quantity of aerosol generating liquid 31 from the reservoir 16 that is sufficient to fill the flow path 32. If the priming means 30 is automatically operated, then the capacity of the pump and the volume of the fluid flow path 32 may be used to calculate a suitable duration or number of cycles of operation that the priming means must perform. Alternatively, at extra cost, a sensor may be provided in the mixing chamber 14 or in the fluid flow path 32 close to the mixing chamber 14, which detects the presence of aerosol generating liquid 31 and indicates that the priming process should stop. However, if the priming means 30 is manually operated, it will be difficult for the user to estimate when priming is complete. If the priming process is continued for too long, excess aerosol generating liquid 31 will be pumped into the mixing chamber 14 and droplets of the liquid 31 will remain there unvaporized, which may result in leakage from the device 2 or may dry and obstruct the free flow of further liquid 31 into the mixing chamber 14 during subsequent use of the system.

Figure 8 illustrates a feature of the aerosol generating system of Figure 1, which addresses both of these problems. As shown in Figure 8, a movable portion 78 of the housing 6 of the device 2, which carries the mouthpiece 10, has been retracted by sliding it laterally along a pair of tracks 80 to reveal the interior of the mixing chamber 14 to view and expose the surface of the liquid transfer element 26. In this case, the liquid transfer element 26 comprises a pair of liquid jet heads 82, which receive aerosol generating liquid 31 via the respective fluid flow paths 32 from the two reservoirs 16 seen in Figure 2. Although in Figure 8 the movable part 78 is shown fully retracted and disengaged from the tracks 80, a stop may be provided to retain the mouthpiece 10 on the device 2 and in engagement with the tracks 80, whereby it can be easily slid back into its working position when desired. In Figure 8, the mouthpiece is shown to have a simple opening 84 directly into the mixing chamber 14 but in other embodiments of the invention, a narrower or more convoluted airflow path may be provided between the mixing chamber 14 and the opening 84 of the mouthpiece.

By retracting the mouthpiece 10 during the priming process, the liquid jet heads 82 are revealed to view. Thus, a user who is priming the system before its first use can observe when all the air has been expelled from the fluid flow path 32 and droplets of aerosol generating liquid 31 start to emerge from the liquid jet heads 82. This indicates that the priming process should be stopped. A wiper on the underside of the retractable mouthpiece 10 (not visible in Figure 8) can be configured to wipe the exposed surfaces of the liquid jet heads 82 as the mouthpiece slides across them back into its working position. The wiper thereby removes from the liquid jet heads 82 any droplets of excess aerosol generating liquid 31 that have been expelled during the priming process. The wiper may take the form of an absorbent pad that retains the excess liquid 31 or it may take the form of a flexible blade that sweeps the excess liquid into an absorbent pad (not shown in Figure 8) positioned adjacent to each liquid jet head 82.

Claims

- 23 - CLAIMS

1. A handheld aerosol generating system comprising: an aerosol generating device (2) containing a mixing chamber (14), in which an aerosol can be generated from an aerosol generating liquid (31); a cartridge (4) removably attached to the aerosol generating device (2), the cartridge (4) comprising a reservoir (16) that contains a supply of the aerosol generating liquid (31); a fluid flow path (32) for conducting the aerosol generating liquid (31) in a forward direction from the reservoir (16) towards the mixing chamber (14) when the system is being used to generate an aerosol; a vent (15,62) for admitting air into the reservoir (16) to replace aerosol generating liquid (31) that is conducted away from the cartridge (4) when the system is being used to generate an aerosol and thereby to maintain the reservoir substantially at ambient pressure when the system is being used to generate an aerosol; and priming means (30) configured to introduce air at above ambient pressure into the reservoir (16) for driving movement of fluid in the forward direction along the fluid flow path (32) to prime the system when the system is not being used to generate an aerosol.

2. A handheld aerosol generating system according to claim 1, wherein the priming means (30) is configured to introduce the air at above ambient pressure into the reservoir (16) through the vent (15).

3. A handheld aerosol generating system according to claim 2, further comprising means for moving the priming means (30) to selectively engage or disengage with the vent (15).

4. A handheld aerosol generating system according to claim 1, further comprising a port (52,63) distinct from the vent (15,62), wherein the priming means (30) is configured to introduce the air at above ambient pressure into the reservoir (16) through the port (52,63).

5. A handheld aerosol generating system according to claim 4, wherein: the priming means (30) further comprises means (54) for sealing the vent (15) while introducing the air at above ambient pressure into the reservoir (16) through the port (52).

6. A handheld aerosol generating system according to claim 4, wherein: the aerosol generating device (2) further comprises an air inlet (64) in communication with the reservoir (16); and the priming means (30) further comprises a three-way valve (60) that can selectively couple the air inlet (64) to the vent (62) to admit air at ambient pressure when the system is being used to generate an aerosol or couple the air inlet (64) to the port (63) to introduce the air at above ambient pressure into the reservoir (16) when the system is being primed.

7. A handheld aerosol generating system according to claim 6, further comprising a cyclically operating pump (46) in communication with the port (63), wherein the three-way valve (60) can further selectively couple the port (63) to the vent (15) to replenish air in the pump (46) during each operating cycle of the pump (46).

8. A handheld aerosol generating system according to claim 6 or claim 7, wherein the three-way valve (60) is a rotary valve.

9. A handheld aerosol generating system according to any preceding claim, wherein the priming means (30) comprises a manual pump (46) for generating the air at above ambient pressure.

10. A handheld aerosol generating system according to any preceding claim, further comprising a liquid transfer element (26) for introducing the aerosol generating liquid (31) from the fluid flow path (32) into the mixing chamber (14).

11. A handheld aerosol generating system according to claim 10, wherein the liquid transfer element (26) is a liquid jet head (82).

12. A handheld aerosol generating system according to claim 10 or claim 11, wherein the aerosol generating device (2) further comprises a movable portion (78) that is capable of movement to expose the liquid transfer element (26) to view while the priming means (30) is in use.

13. A handheld aerosol generating system according to claim 12, wherein: the movable portion (78) of the aerosol generating device (2) is capable of movement to conceal the liquid transfer element (26) from view while the priming means (30) is not in use; the movement to conceal the liquid transfer element (26) is generally parallel to a surface of the liquid transfer element (26); and the movable portion (78) comprises means for wiping aerosol generating liquid (31) from the surface of the liquid transfer element (26) during the movement to conceal the liquid transfer element (26).

14. A method of operating a handheld aerosol generating system, the system comprising: an aerosol generating device (2) containing a mixing chamber (14), in which an aerosol can be generated from an aerosol generating liquid (31); a cartridge (4) removably attached to the aerosol generating device (2), the cartridge (4) comprising a reservoir (16) that contains a supply of the aerosol generating liquid (31); and a vent (15); the method comprising: when the system is not being used to generate an aerosol, operating a priming means (30) to introduce air at above ambient pressure into the reservoir (16), thereby to drive movement of fluid along a fluid flow path (32) in a forward direction from the reservoir (16) towards the mixing chamber (14); and when the system is being used to generate an aerosol, admitting air through the vent (15) into the reservoir (16) to replace aerosol generating liquid (31) that is - 26 - conducted away from the cartridge (4), thereby to maintain the reservoir substantially at ambient pressure.

15. A method according to claim 14, wherein: the handheld aerosol generating system further comprises a liquid transfer element (26) for introducing the aerosol generating liquid (31) from the fluid flow path (32) into the mixing chamber (14); the method further comprising: moving a movable portion (78) of the aerosol generating device (2) to expose the liquid transfer element (26) to view while the priming means (30) is in use; and moving the movable portion (78) of the aerosol generating device (2) generally parallel to a surface of the liquid transfer element (26) to conceal the liquid transfer element (26) from view while the priming means (30) is not in use, whereby wiping means on the movable portion (78) wipe aerosol generating liquid (31) from the surface of the liquid transfer element (26).