WO2023083646A1 - Aerosol generating systems - Google Patents

Abstract

A handheld vapour generating system comprises a cartridge (4) removably attached to an aerosol generating device (2), the cartridge (4) supplying an aerosol generating liquid to mixing chamber (14) along a fluid flow path (32). A priming pump (30) may be used to drive movement of fluid along the fluid flow path (32) when the system is not being used to generate an aerosol, in order to expel any air that entered the fluid flow path (32) when the cartridge (4) was attached. The priming pump (30) may comprise a combination of a fixed valve (33) and a moving valve (34) within the fluid flow path (32). Alternatively, a portion of the fluid flow path (32) may comprise a resiliently compressible tube (100) and the priming pump (30) may first form a constriction (120,134,142) in the tube then compress the tube (100) forward of the constriction (120,134,142) to expel fluid.

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 that may or may not be mixed with air.

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 aerosol 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 containing a supply of the aerosol generating liquid; a fluid flow path for conducting the aerosol generating liquid in a forward direction from the cartridge to the mixing chamber when the system is being used to generate an aerosol; and a priming pump for selectively 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 fluid driven along the fluid flow path by the priming pump may comprise the aerosol generating liquid, air or a mixture of the two. It 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.

In some embodiments of the invention, the priming pump comprises a fixed valve in the fluid flow path, which permits fluid to pass therethrough only in the forward direction; and a moving valve in the fluid flow path, which permits fluid to pass therethrough only in the forward direction and which is configured to move reciprocally along the fluid flow path relative to the fixed valve. The fixed valve and the reciprocally moving valve co-operate to pump fluid along the fluid flow path. They can be configured as a micro-pump for use in a narrow conduit, which is suitable for a handheld system.

Preferably, the moving valve comprises a magnet and is surrounded by an electromagnetic coil, which is operable to drive the movement of the moving valve in at least the forward direction. Using an electromagnet to drive the pump is a compact and efficient solution, which can easily be powered and controlled by a battery and processor that are already present in such aerosol generating systems. The moving valve may further comprise a return spring that drives the movement of the moving valve in the backward direction. Storing energy in a return spring during the forward movement of the valve then using it to drive the backward movement is an energy-efficient solution which simplifies the electronics because the electromagnet needs to drive the valve only in one direction.

The fixed valve and the moving valve may be ball valves, which are robust and reliable.

In other embodiments of the invention, a portion of the fluid flow path comprises a resiliently compressible tube; and the priming pump is configured to compress the tube to displace fluid in the forward direction along the fluid flow path. In such embodiments, the priming pump is external to the fluid flow path so it does not need to be accommodated within a narrow space and does not interfere with the flow of the aerosol generating liquid during normal use of the system. This arrangement also permits a wider range of mechanical means to be used as the priming pump. A potential disadvantage is that a flexible tube that is repeatedly compressed may lose its resilience with time and may be prone to failure, either in the region that is compressed or at its junction with other portions of the fluid flow path.

A priming pump for use with a resiliently compressible tube may be configured to carry out a first motion that compresses the tube to form a constriction, then to carry out a second motion that further compresses the tube forward of the constriction to displace the fluid. The initial constriction ensures that fluid cannot be driven in the backward direction, whereby the fluid displaced by the second motion can travel only in the forward direction.

The priming pump may comprise a first element that is configured to carry out the first motion; and a second element that is configured to be moved independently of the first element to carry out the second motion. This potentially increases the number of components but allows the shape and movement of each element to designed in the best way to perform the sole function of that element. Altematively, the priming pump may comprise a single element that is configured to carry out the first motion then the second motion. This reduces the number of components and may simplify the operation of the priming pump but its performance (e.g. the capacity of the pump on each stroke) may be adversely affected. In certain embodiments of the invention, the second motion comprises a pivotal movement of the single element, which can be effective to squeeze fluid out of the compressible tube while urging it in the forward direction.

In some embodiments of the invention with a resiliently compressible tube, the priming pump may be operated manually by pressing a button.

The priming pump is preferably provided in the aerosol generating device. The alternative would be to provide it in the cartridge but, even if reusable, the cartridge is likely to have a shorter life than the device so it is desirable to keep the cartridge as simple and cheap as possible.

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 at that time and/or because there is no airflow through the mixing chamber. 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 invention further provides a method of priming 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, and a cartridge removably attached to the aerosol generating device, the cartridge comprising a reservoir that contains a supply of the aerosol generating liquid; the method comprising, when the system is not being used to generate an aerosol, operating a priming pump to drive movement of fluid along a fluid flow path in a forward direction from the reservoir towards the mixing chamber.

According to some embodiments of the invention, the priming pump comprises a fixed valve in the fluid flow path, which permits fluid to pass therethrough only in the forward direction, and a moving valve in the fluid flow path, which permits fluid to pass therethrough only in the forward direction; the moving valve comprising a magnet and being configured to move reciprocally along the fluid flow path relative to the fixed valve. Then the method of priming the handheld aerosol generating system preferably further comprises operating an electromagnetic coil that surrounds the moving valve to drive the movement of the moving valve in at least the forward direction.

Alternatively, the method of priming the handheld aerosol generating system may comprise operating the priming pump to carry out a first motion that compresses the tube to form a constriction, then to carry out a second motion that further compresses the tube forward of the constriction to displace the fluid in the forward direction along the fluid flow path.

According to some embodiments of the invention, the aerosol generating device further comprises a liquid transfer element for introducing the aerosol generating liquid from the fluid flow path into the mixing chamber; and a movable portion that comprises a wiper. Then the method of priming the handheld aerosol generating system preferably further comprises moving the movable portion to expose the liquid transfer element to view while the priming means is in use; and moving the movable portion generally parallel to a surface of the liquid transfer element to conceal the liquid transfer element from view while the priming means is not in use, whereby, during the movement to conceal the liquid transfer element, the wiper wipes aerosol generating liquid from the surface of the liquid transfer element.

The drawings

Figure 1 is a perspective view of an example of a handheld aerosol 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 indicating the preferred location of a priming pump according to the present invention.

Figures 3A and 3B show two stages in the operation of a priming pump according to a first embodiment of the present invention, which comprises ball valves.

Figure 4 is a perspective view of the fixed valve of Figure 3.

Figure 5 is a perspective view of the moving valve of Figure 3.

Figure 6 is a schematic diagram of a second embodiment of the present invention, which comprises a manually operated priming pump.

Figures 7A and 7B are schematic diagrams of two stages in the manual operation of the priming pump according to the second embodiment of the present invention.

Figures 8A and 8B are schematic diagrams of two stages in the manual operation of a priming pump according to a third embodiment of the present invention.

Figures 9A and 9B are schematic diagrams of two stages in the manual operation of a priming pump according to a fourth embodiment of the present invention.

Figure 10 is a perspective view of the handheld aerosol generating system of Figure 1, in which the mouthpiece has been retracted.

Figure 1 illustrates a handheld aerosol generating system, comprising a 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 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 and other components of the aerosol generating device 2 are not shown in Figure 2.

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 channel through which the air enters the reservoir 16 is not visible in the plane of Figure 2. It preferably comprises a one-way valve 15 (not shown in Figure 2) to prevent aerosol generating liquid leaking out of the channel. 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 fluid 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 fluid from the cartridge 4 and prevents contamination of the aerosol generating fluid 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 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. The liquid jet head may thereby create an aerosol directly, without first vaporizing and then condensing the liquid.

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 illustrated embodiment comprises a pump 30 that may be used to prime the system by expelling air from the fluid flow path before the device 2 is used and, in particular, before the first use of the device 2 after a new cartridge 4 has been installed. The pump 30 may take various forms, to be described below, so in Figure 2 it is indicated purely schematically by a circle.

The pump 30 is preferably provided as part of the aerosol generating device 2. Accordingly, the pump acts on fluid in either the second tube 22 or the conduit 24. It would alternatively be possible to provide the pump 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). The pump 30 drives whatever combination of aerosol generating liquid and air may be present 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, while the upstream, distal end of the fluid flow path is refilled from the reservoir 16. 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 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 is 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 pump 30 is in operation. If the pump 30 is operated electronically, then the operation of the valve could similarly be under electronic control. Alternatively, given that the pump 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.

Figures 3A and 3B illustrate one example of a priming pump 30, which may be used in a aerosol generating system according to the present invention. This type of pump 30 is deployed within a portion 32 of the fluid flow path, which may represent, for example, the second tube 22 or the conduit 24 of Figure 2. The pump 30 comprises a fixed valve 33 and a moving valve 34. In this embodiment, the valves 33,34 are ball valves but other types of valve that permit fluid flow through them in one direction but not in the opposite direction are possible.

The fixed ball valve 33 is illustrated in more detail in Figure 4. It comprises a generally cylindrical cage 36 with a plurality of side openings 38 in its side walls, an upstream opening 40 in the centre of its upstream end wall and a downstream opening 42 in the centre of its downstream end wall. A collar 44 around the exterior of the cage 36, upstream from the side openings 38, fixes the valve 33 in the flow path 32 and seals around it so that fluid can traverse the valve 33 only by flowing through the upstream opening 40. A ball 45 is trapped inside the cage 36 such that it can move a short distance in the longitudinal direction but cannot undergo significant movement in the transverse direction. When fluid pressure upstream of the valve 33 is lower than fluid pressure downstream of the valve 33, fluid briefly enters the cage 36 through the downstream opening 42 and pushes the ball 45 in the upstream direction. The ball 45 rapidly blocks the upstream opening 40, thereby preventing any further backward fluid flow through the valve 33. When fluid pressure upstream of the valve 33 is higher than fluid pressure downstream of the valve 33, the ball 45 moves in the downstream direction, unblocking the upstream opening 40 and allowing fluid to flow in through the upstream opening 40, around the ball 45 and out through the side openings 38 to continue its flow in the forward direction along the flow path 32.

The moving ball valve 34 is illustrated in more detail in Figure 5. Its downstream end is generally similar to the fixed ball valve 33, comprises a generally cylindrical cage 46 with a plurality of side openings 48 in its side walls, an upstream end opening 50 in the centre of its upstream end wall and a downstream end opening 52 in the centre of its downstream end wall. A collar 54 around the exterior of the cage 46, upstream from the side openings 48, seals around the valve 34 so that fluid can traverse the valve 34 only by flowing through the upstream end opening 50. In this case, the collar 54 does not fix the valve 34 in the flow path 32 but allows it to slide along at least a predetermined length of the flow path 32. A ball 55 is trapped inside the cage 46 such that it can move a short distance in the longitudinal direction but cannot undergo significant movement in the transverse direction.

The upstream end of the moving valve 34 comprises a hub 58 that is fixed to the cage 46 and extends along the axis of the valve 34 upstream of the upstream end opening 50. A plurality of peripheral openings 60 are in fluid communication with the upstream end opening 50 and allow fluid flowing past the hub 58 to reach the upstream end opening 50. The hub 58 further carries a ring of radial supports 62, of which outer surfaces 64 slide against or close to the wall of the flow path 32 to maintain the alignment of the moving valve 34 when it moves in the flow path 32, while permitting fluid to flow through gaps 66 between the radial supports 62.

The hub 58 of the moving valve 34 carries a permanent magnet 70 and the fluid path 32 in the region of the moving valve 34 is surrounded by an electromagnetic coil 72. Passing an electric current through the coil 72 in one direction generates a magnetic field that interacts with the field of the permanent magnet 70 to drive movement of the moving valve 34 in the downstream direction. Passing an electric current through the coil 72 in the opposite direction would in principle drive movement of the moving valve 34 in the upstream direction. However, it is preferred simply to de-energize the coil 72 and allow a return spring 73 to drive the moving valve 34 in the upstream direction back to its initial position. The return spring 73 may be seated on the fixed valve 32.

Figures 3A and 3B show how the fixed valve 33 and the moving valve 34 can be used in combination as a priming pump 30 to pump fluid in the forward direction along the fluid flow path 32. In Figure 3A, the coil 72 is energized to drive the moving valve 34 in the forward (downstream) direction, as shown by the arrow 74. This causes fluid to enter the valve cage 46 through the downstream end opening 52 and rapidly forces the ball 55 to block the upstream end opening 50 and close the moving valve 34, as shown by the arrow 76. Thereafter, continued forward movement of the valve 34 pushes fluid ahead of it towards the fixed valve 33. The moving fluid pushes the ball 45 of the fixed valve 33 in the downstream direction to open the fixed valve 33, as shown by the arrow 78. The fluid that the moving valve 34 displaces from between the two valves 33,34 therefore flows through the fixed valve 33 and is pumped forwards along the fluid flow path 32, as shown by the arrows 80. The forward movement of the moving valve 34 simultaneously draws a fresh supply of aerosol generating liquid from the reservoir 16 to fill the portion of the fluid flow path that is upstream of the pump 30, as shown by the arrows 81. Thus the possible mixture of liquid and air in the flow path 32 is replaced by pure liquid.

In Figure 3B, the coil 72 is de-energized and the return spring 73 drives the moving valve 34 back in the upstream direction, as shown by the arrow 82. The widening space 84 between the valves 33,34 must be filled with fluid but the ball 45 of the fixed valve 33 rapidly moves to block its upstream end opening 40, as shown by the arrow 86. The fixed valve 33 is therefore closed and backward flow of fluid along the flow path 32 to fill the space is prevented. Fluid therefore flows in the forward direction through the moving valve 34 - or more accurately the moving valve 34 moves in the backward direction relative to the fluid. The ball 55 of the moving valve moves away from the upstream end opening 55 to allow this to happen, as shown by the arrow 88. Specifically, as shown by the arrows 90, the fluid flows through the gaps 66 between the radial supports 62, past the hub 58, enters the peripheral openings 60, passes through the upstream end opening 50 and travels around the ball 55 to emerge through the side openings 48 of the moving valve 34 and enter the space 84.

The cycle can then be repeated until a sufficient volume of fluid has been pumped to be confident that the fluid remaining in the flow path is purely aerosol generating liquid, without any trapped air. The capacity of the pump 30 based on ball valves is determined by the volume of the space 84 between the two valves 33,34.

The orientation of the moving valve 34 and the fixed valve 33 is such that during normal use of the aerosol generating system, aerosol generating liquid drawn along the fluid flow path 32 is able to flow through both valves 33,34 in the forward direction. The moving valve 34 remains essentially stationary during this time. The force of the return spring 73 is preferably sufficient to counteract any drag caused by the flow of liquid through the valve 34 and to hold it in position.

Figure 6 is a highly schematic diagram of a second embodiment of the present invention, in which the priming pump 30 is manually operated. Once more, a reservoir 16 supplies aerosol generating liquid via a fluid flow path 32 to a liquid transfer element 26 for delivery into a mixing chamber 14 of the aerosol generating device 2. The volume of liquid removed from the reservoir 16 may be replaced by air drawn in through a valve 15.

A portion of the fluid flow path 32, illustrated in Figure 6 with thinner walls, comprises a resiliently compressible tube 100. The priming pump 30 comprises a manually operable rod 102, which is mounted in the device 2 with an axis of the rod 102 generally transverse to the longitudinal direction of the compressible tube 100. When the rod 102 is moved parallel to its length, ahead 104 of the rod engages the compressible tube 100 and compresses it in two stages: first to form a constriction in the tube 100, then to squeeze the tube 100 forward of the constriction to displace fluid therefrom in the forward direction, indicated by the arrow 105. An anvil 106 is provided adjacent to the compressible tube 100, on the opposite side from the rod 102 so that the head can compress the tube 100 against the anvil 106. Various options for the configuration of the head 104 will be described below. A one-way valve (not shown) may need to be provided in the fluid flow path 32 to ensure that, when the head 104 is released and the compressible tube 100 resiliently expands to its original size and shape, fluid is not drawn back along the flow path 32 but travels only forwards from the reservoir 16 to replenish the flow path 32 with pure aerosol generating liquid. The outer end of the rod 102 may be provided with a button 108 (not shown to scale), which can be pressed by the thumb or a finger of a user of the aerosol generating system to effect the inward movement of the rod 102. A return spring 110 mounted, for example, between the housing 6 and the button 108, urges the rod 102 back outwards to its initial position when the button 108 is released. This reciprocal actuation of the rod 102, indicated by the arrow 112, may be repeated several times to prime the system by pumping fluid out of the fluid flow path 32 until the user can be reasonably confident that no air remains and the fluid flow path 32 is filled only with the aerosol generating liquid.

It will be understood that the button 108 for manually actuating the movement of the rod 102 could easily be replaced in other embodiments of the invention by an electrical actuator, such as a solenoid or a small motor (not illustrated) powered by the battery of the aerosol generating system.

Figures 7A and 7B schematically show one example of a head 104 that can be used with the manual priming pump 30 of Figure 6. In this example, the head 104 takes the form of a wedge 114 that is pivotally mounted at the end of the rod 102. In Figure 7A, in a first motion the button 108 has been pressed through a first distance, shown by the arrow 116, from its initial position, shown by a dashed line 117, so that a comer 118 of the wedge 114 engages the compressible tube 100 and compresses it against the anvil 106. This forms a constriction 120 in the tube 100 that prevents or resists the flow of fluid along the fluid flow path 32 past the constriction 120. In Figure 7B, in a second motion the button 108 has been pressed through a further distance, shown by the arrow 122, which causes the wedge 114 to pivot so that a compression surface 123 of the wedge 114 compresses a segment 124 of the tube 100 forward (downstream) of the constriction 120. This expels fluid from that segment 124 of the tube 100 and, because of the constriction 120 in the upstream direction, the expelled fluid is forced to travel forwards, as shown by the arrow 126. Upon releasing the button 108, the return spring 110 drives the button 108 back to its initial position 117 and the head 106 is removed from the compressible tube 100, which rebounds to its original shape. This allows aerosol generating liquid from the reservoir 16 to flow into the segment 124 of the tube that was previously compressed, then the cycle can be repeated by pressing the button 108 a number of times to prime the system by pumping fluid along the fluid flow path 32 until there can be reasonable confidence that any air has been expelled. The capacity of the pump 30 is determined by the volume of the compressed segment of tube 124.

The pivotally mounted wedge 114 may need to be provided with means (not shown) to resist its pivotal movement relative to the rod 102, in order to ensure that the tube 100 is fully constricted before fluid is expelled from the further segment 124. Such resistance could be offered by a liner or rotary spring, which would also provide the benefit of returning the wedge 114 to its initial angle when it is withdrawn from the tube 100 at the end of each cycle of operating the pump 30.

It will be understood that Figures 7A and 7B are highly schematic and the wedge 114 may take forms other than those illustrated. In particular, the comer 118 of the wedge may be rounded to avoid damage to the tube 100. The compression surface 123 may be curved to control the expulsion of fluid from the segment 124. The anvil 106 may also be curved to co-operate more effectively with the wedge 114.

Figures 8 A and 8B schematically show another example of ahead 104 that can be used with the manual priming pump 30 of Figure 6. In this example, the head 104 takes the form of a roller 128 that is eccentrically and pivotally mounted at the end of the rod 102. In Figure 8 A, in a first motion the button 108 has been pressed through a first distance, shown by the arrow 116, from its initial position, shown by a dashed line 117, so that a compression surface 130 of the roller 128 engages the compressible tube 100 and compresses it against the anvil 106 at a point upstream from the pivot point 132. This forms a constriction 134 in the tube 100 that prevents or resists the flow of fluid along the fluid flow path 32 past the constriction 134. In Figure 8B, in a second motion the button 108 has been pressed through a further distance, shown by the arrow 122, which causes the roller 128 to pivot so that the compression surface 130 of the roller 128 rolls about the pivot point 132 and moves the constriction 134 in the tube 100 in the forward (downstream) direction. This expels fluid from a segment 136 of the tube 100 between the location of the initial constriction and a location directly below the pivot point 132. Because the constriction 134 of the tube 100 is maintained while moving downstream, the expelled fluid is forced to travel forwards, as shown by the arrow 126.

As before, upon releasing the button 108, the return spring 110 drives the button 108 back to its initial position 117 and the head 106 is removed from the compressible tube 100, which rebounds to its original shape so the cycle can be repeated. The capacity of the pump 30 is determined by the volume of the segment of tube 136 along which the roller 128 travels. It could be increased by increasing the diameter of the roller 128.

As with the wedge 114 of Figures 7A and 7B, the roller 128 may need to be provided with means (not shown) to resist its pivotal movement relative to the rod 102, in order to ensure that the tube 100 is fully constricted before the roller 128 begins to pivot.

It will be understood that Figures 8 A and 8B are highly schematic and the roller 128 may take forms other than those illustrated. For example, it will be noted that only part of the surface 130 of the roller 128 makes contact with the tube 100 so the roller 128 could be formed as a sector comprising only the required parts of the surface 130. The compression surface 130 of the roller does not need to be in the shape of a circular arc but could take the form of other curves to control the force exerted on the tube 100 and the expulsion of fluid from the segment 136.

Figures 9A and 9B schematically show a still further example of ahead 104 that can be used with the manual priming pump 30 of Figure 6. In this example, the pump 30 is divided into two distinct elements: a first element 140 that forms a constriction 142 in the compressible tube 100; and a second element 144 that compresses the tube 100 downstream of the constriction 142 to expel fluid from a segment 146 of the tube 100 and drive it in the forward direction. The first element 140 comprises a first button part 108a atached to a first rod part 102a, which is mounted to move reciprocally relative to the housing 6 against the force of a first return spring 110a. The second element 144 comprises a second buton part 108b atached to a second rod part 102b, which is mounted to move reciprocally relative to the housing 6 against the force of a second return spring 110b.

In Figure 9A, in a first motion the first buton part 108a has been pressed through a first distance, shown by the arrow 148, from its initial position, shown by a dashed line 117, so that a first head part 104a at the end of the first rod part 102a engages the compressible tube 100 and compresses it against the anvil 106 at a point upstream from the pivot point 132. This forms the constriction 142 in the tube 100. that prevents or resists the flow of fluid along the fluid flow path 32 past the constriction 142. In Figure 9B, in a second motion the second buton part 108b has been pressed through a similar distance, shown by the arrow 152, which causes a second head part 104b at the end of the second rod part 102b to compress the segment 146 of the tube 100 forward (downstream) of the constriction 142. This expels fluid from that segment 146 of the tube 100 and, because of the constriction 142 in the upstream direction, the expelled fluid is forced to travel forwards, as shown by the arrow 126.

Upon releasing both parts of the buton 108a, 108b, the respective return springs 110a, 110b drive the buton parts 108a, 108b back to their initial position 117 and the respective head parts 104a, 104b are removed from the compressible tube 100, which rebounds to its original shape. This allows aerosol generating liquid from the reservoir 16 to flow into the segment 146 of the tube that was previously compressed, then the cycle can be repeated by pressing the button 108 a number of times to prime the system fully. The capacity of the pump 30 is determined by the volume of the compressed segment of tube 146.

It will be understood that Figures 9A and 9B are highly schematic and the elements 140,144 may take forms other than those illustrated. In particular, the first head part 104a is shown in the drawings as simply the tip of the first rod part 102a but it could be formed as a distinct component with a specific shape to constrict the tube 100 effectively and without damage. The second head part 104b is shown with a simple, flat compression surface 154 but it could be curved to control the expulsion of fluid from the compressed segment 146. The anvil 106 could similarly be curved to cooperate effectively with the first and second head parts 104a, 104b. It would be possible to couple the first and second rod parts 102a, 102b together in such a way that the button 108 would be common to both rod parts 102a, 102b and would not need to be split. In such an arrangement, pressing the common button 108 through a first distance would effect the first motion of the first rod part 102a to constrict the tube 100 then pressing the common button 108 through a further distance would effect the second motion of the second rod part 102b to compress the tube 100 downstream of the constriction 142.

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 from the reservoir 16 that is sufficient to fill the flow path 32. If the priming pump 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 and indicates that the priming process should stop. However, if the priming pump 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 will be pumped into the mixing chamber 14 and droplets of the liquid will remain there unvaporized, which may result in leakage from the device 2 or may dry and obstruct the free flow of further liquid into the mixing chamber 14 during subsequent use of the system.

Figure 10 illustrates a feature of the aerosol generating system of Figure 1, which addresses both of these problems. As shown in Figure 10, a movable portion 178 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 180 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 182, which receive aerosol generating liquid via the respective fluid flow paths 32 from the two reservoirs 16 seen in Figure 2. Although in Figure 10 the mouthpiece 10 is shown fully retracted and disengaged from the tracks 180, a stop may be provided to retain the mouthpiece 10 on the device 2 and in engagement with the tracks 180, whereby it can be easily slid back into its working position when desired. In Figure 10, the mouthpiece is shown to have a simple opening 184 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 184 of the mouthpiece.

By retracting the movable part 178 during the priming process, the liquid jet heads 182 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 start to emerge from the liquid jet heads 182. This indicates that the priming process should be stopped. A wiper 190 on the underside of the retractable mouthpiece 10 (not visible in Figure 10) can be configured to wipe the exposed surfaces of the liquid jet heads 182 as the mouthpiece slides across them back into its working position. The wiper 190 thereby removes from the liquid jet heads 182 any droplets of excess aerosol generating liquid that have been expelled during the priming process. The wiper 190 may take the form of an absorbent pad that retains the excess liquid or it may take the form of a flexible blade that sweeps the excess liquid into an absorbent pad (not shown in Figure 10) positioned adjacent to each liquid jet head 182.

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; a cartridge (4) removably attached to the aerosol generating device (2), the cartridge (4) containing a supply of the aerosol generating liquid; a fluid flow path (32) for conducting the aerosol generating liquid in a forward direction from the cartridge (4) to the mixing chamber (14) when the system is being used to generate an aerosol; and a priming pump (30) for selectively driving movement of fluid in the forward direction along the fluid flow path (32) when the system is not being used to generate an aerosol.

2. A vapour generating system according to claim 1, wherein the priming pump (30) comprises: a fixed valve (33) in the fluid flow path (32), which permits fluid to pass therethrough only in the forward direction; and a moving valve (34) in the fluid flow path (32), which permits fluid to pass therethrough only in the forward direction and which is configured to move reciprocally along the fluid flow path (32) relative to the fixed valve (33); wherein the moving valve (34) comprises a magnet (70) and is surrounded by an electromagnetic coil (72), which is operable to drive the movement of the moving valve (34) in at least the forward direction.

3. An aerosol generating system according to claim 2, wherein the moving valve (34) further comprises a return spring (73) that drives the movement of the moving valve (34) in the backward direction.

4. An aerosol generating system according to claim 2 or claim 3, wherein the fixed valve (33) and the moving valve (34) are ball valves.

5. An aerosol generating system according to claim 1, wherein: a portion of the fluid flow path (32) comprises a resiliently compressible tube (100); and the priming pump (30) is configured to carry out a first motion that compresses the tube (100) to form a constriction (120,134,142), then to carry out a second motion that further compresses the tube (100) forward of the constriction (120,134,142) to displace the fluid in the forward direction along the fluid flow path (32).

6. An aerosol generating system according to claim 5, wherein the priming pump (30) comprises a first element (140) that is configured to carry out the first motion; and a second element (144) that is configured to be moved independently of the first element (140) to carry out the second motion.

7. An aerosol generating system according to claim 5, wherein the priming pump (30) comprises a single element (104) that is configured carry out the first motion then the second motion.

8. An aerosol generating system according to claim 7, wherein the second motion comprises a pivotal movement of the single element (104).

9. An aerosol generating system according to any of claims 5 to 8, further comprising a button (108) for manual operation of the priming pump (30).

10. A handheld vapour generating system according to any preceding claim, further comprising a liquid transfer element (26) for introducing the aerosol generating liquid from the fluid flow path (32) into the mixing chamber (14), wherein: the aerosol generating device (2) further comprises amovable portion (178) that is capable of movement to expose the liquid transfer element (26) to view while the priming means (30) is in use and 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 (178) comprises a wiper (190) for wiping aerosol generating liquid from the surface of the liquid transfer element (26) during the movement to conceal the liquid transfer element (26).

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

12. A method of priming 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; and 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; the method comprising, when the system is not being used to generate an aerosol, selectively operating a priming pump (30) to drive movement of fluid along a fluid flow path (32) in a forward direction from the reservoir (16) towards the mixing chamber (14).

13. A method according to claim 12, wherein the priming pump (30) comprises a fixed valve (33) in the fluid flow path (32), which permits fluid to pass therethrough only in the forward direction, and a moving valve (34) in the fluid flow path (32), which permits fluid to pass therethrough only in the forward direction; the moving valve (34) comprising a magnet (70) and being configured to move reciprocally along the fluid flow path (32) relative to the fixed valve (33); the method further comprising operating an electromagnetic coil (72) that surrounds the moving valve (34) to drive the movement of the moving valve (34) in at least the forward direction.

14. A method according to claim 12, comprising operating the priming pump (30) to carry out a first motion that compresses the tube (100) to form a constriction (120,134,142), then to carry out a second motion that further compresses - 26 - the tube (100) forward of the constriction (120,134,142) to displace the fluid in the forward direction along the fluid flow path (32).

15. A method according to claim 12, wherein the aerosol generating device (2) further comprises a liquid transfer element (26) for introducing the aerosol generating liquid from the fluid flow path (32) into the mixing chamber (14); and a movable portion (178) that comprises a wiper (190); the method further comprising: moving the movable portion (178) to expose the liquid transfer element (26) to view while the priming means (30) is in use; and moving the movable portion (178) 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, during the movement to conceal the liquid transfer element (26), the wiper wipes aerosol generating liquid from the surface of the liquid transfer element (26).