A vaporiser for an aerosol generative device

Abstract

A vaporiser (200) for an aerosol generative device is provided. The vaporiser (200) comprises: a vaporising unit (340); a liquid reservoir (330), wherein the liquid reservoir (330) is in fluid communication with the vaporising unit (340); and a liquid feeding structure (270). The liquid feeding structure (270) defines two or more compartments (290, 292, 294) within the liquid reservoir (330) which are in fluid communication wherein the two or more compartments (290, 292, 294) are arranged such that liquid in the liquid reservoir (330) flows sequentially through the two or more compartments (290, 292, 294) when flowing towards or away from the vaporising unit (340) during use. Furthermore, the liquid feeding structure (270) is arranged so as to increase the length of a fluid flow path through the liquid reservoir (330).

Description

FIELD OF THE INVENTION

[0001] This application relates to a vaporiser for an aerosol generative device and a method of manufacture of said vaporiser.BACKGROUND

[0002] Aerosol generative devices can be used as an alternative to conventional cigarettes. Instead of generating a combustion smoke, they vaporise a liquid, which can be inhaled by a user. The liquid typically comprises an aerosol-forming substance, also known as a vaporising agent, such as glycerin or propylene glycol that creates the vapor. Other common substances in the liquid are nicotine and various flavourings.

[0003] The aerosol generative devices are often hand-held systems, comprising a mouthpiece section, a liquid reservoir, a vaporising unit, and a power supply.

[0004] The vaporising section typically comprises a heating element in the form of a heating coil and a fluid transfer element, such as a wick or pad, arranged to transfer fluid from the liquid holding section to the heating element, usually via capillary action.

[0005] Vaporisation occurs when the heating coil heats up the liquid in the fluid transfer element until the liquid is transformed into vapor. The vapor can then be inhaled via an air outlet in the mouthpiece.

[0006] However, vaporising agents such as propylene glycol and glycerin are hygroscopic and absorb water from the moisture in the air. Therefore, at any air-liquid interface between vaporising agents and the air, there is an absorption of water into the vaporisable liquid.

[0007] Environmental factors, such as high atmospheric moisture levels, are the main cause of the water content increase in the vaporising agents. However, moisture from the user's breath can also increase the water content absorbed into the vaporising agents.

[0008] The water absorbed from the air can enter the liquid reservoir via diffusion from the air-liquid interface. Importantly, the increase in water content in the vaporising liquid in turn results in an increase in the volume of the liquid. Therefore, an increase in water content in the vaporisable liquid negatively affects the quality of the aerosol generative device.

[0009] The quality may be negatively impacted as an increase in water content, and therefore the volume of vaporisable liquid, results in the leakage of the vaporisable liquid out of the liquid reservoir. This is shown to promote the accumulation of the vaporising agents in the vaporising chamber of the mouthpiece section. Furthermore, this can result in an unwanted taste in the mouth of the consumer after inhalation and / or cause the vaporising agent to leak out of the device.

[0010] As discussed above, environmental factors, such as high atmospheric moisture levels, are the main source of the water content increase in the vaporizing agents and therefore these factors are often the main cause in occurrences of liquid leakage from a liquid reservoir.

[0011] The leakage of the vaporisable liquid in aerosol generative devices represents a global concern for the producers of such devices.

[0012] Currently, the solutions provided for overcoming the above problem, namely of vaporisable liquid leakage due to the absorption of moisture and the subsequent volume increase, focus on mitigating the negative results of the volume increase. For example, some of the solutions provided so far include: overflow channels for additional volume; pressure equalising vents and movable walls and ceilings within a reservoir; and absorbent pads within an overflow leak chamber and elastomeric tank caps.

[0013] Therefore, current solutions solve the problem via an increase in total available internal volume. However, these solutions are complex and increase the unit cost of the aerosol generative devices.

[0014] Consequently, there is a need to provide a simple and low-cost solution to overcome the problems discussed above.SUMMARY OF INVENTION

[0015] According to a first aspect of the invention, a vaporiser for an aerosol generative device is provided. The vaporiser comprises: a vaporising unit; a liquid reservoir, wherein the liquid reservoir is in fluid communication with the vaporising unit; and a liquid feeding structure. The liquid feeding structure defines two or more compartments within the liquid reservoir which are in fluid communication, wherein the two or more compartments are arranged such that liquid in the liquid reservoir flows sequentially through the two or more compartments when flowing towards or away from the vaporising unit during use. Furthermore, the liquid feeding structure is arranged so as to increase the length of a fluid flow path through the liquid reservoir.

[0016] The first aspect of the invention allows for a reduced rate of water absorption into the vaporisable liquid, and therefore the rate of volume increase of the vaporisable solution is reduced compared to current aerosol generative devices. The reduced rate of water absorption is achieved in the first aspect due to the increase in the flow path of the vaporisable liquid through the liquid reservoir. The increase in the flow path of the vaporisable liquid effectively increases the distance over which the absorption of the water into the vaporisable liquid occurs. As previously discussed, the interface between air and vaporisable liquid is where the absorption of moisture takes place. This interface is at the wick as it is well aerated by an air flow stream. Therefore, as the flow path of the vaporisable liquid from the wick into the liquid reservoir is increased it results in a reduced rate of diffusion of water into the vaporisable liquid. Thus, as the rate of water diffusion into the vaporisable liquid has been reduced, so too has the rate at which the volume taken up by the vaporisable liquid increases. As a consequence of the rate at which the rate of moisture diffuses into the vaporisable liquid, the leakage of vaporisable liquids is mitigated.

[0017] Therefore, the first aspect of the invention provides a means to mitigate the leakage of vaporisable liquid from the liquid reservoir via a reduction in moisture absorption rate.

[0018] The first aspect of the invention allows for such beneficial outcomes, for example the reduction in vaporisable liquid leakage, without the need for complex structures or additional moving parts.

[0019] A vaporising unit can be understood to be the unit within an aerosol generative device which provides the functionality of turning a liquid substrate into a vapour. A vaporising unit comprises components which allow for a substrate to be vaporised; for example, the vaporising unit may comprise a heating coil and a wick.

[0020] An aerosol generative device may also be known as an e-cigarette or a vape.

[0021] The vaporiser may be a replaceable cartridge forming a part of an aerosol generative device, e-cigarette, or vape. Alternatively, the vaporiser may be a integral part of the aerosol generative device, e-cigarette, or vape.

[0022] A liquid reservoir can be understood to mean the portion of the vaporiser which stores the vaporisable liquid. The liquid reservoir can take the form of a single structure or a plurality of distinct structures which are in fluid communication.

[0023] Fluid communication can be understood to mean that a fluid can move between two regions. For example, two or more compartments within the liquid reservoir are in fluid communication means that the vaporisable liquid can move between the compartments without significant difficulty.

[0024] A compartment can be understood to be a region within the vaporiser which substantially encapsulates a portion of vaporisable liquid. In this context, substantially encapsulates means that the compartment is defined by walls or partitions which enclose the majority of the compartment.

[0025] A liquid feeding structure can be understood to be a structure within the aerosol generative device which is configured to impact the flow of the vaporisable liquid within the aerosol generative device. In particular the liquid feeding structure comprises a structure that increases the length of a fluid flow path through the liquid reservoir. The term impact the flow can be understood to mean that the flow is diverted, changed, delayed, hampered or otherwise affected.

[0026] Sequential flow can be understood as the movement of the liquid from one compartment to another in such a way that each compartment is passed through in a predetermined order without a compartment being missed.

[0027] Preferably, the liquid in the liquid reservoir has to go through the liquid feeding structure before getting to the vaporising unit. Preferably the liquid feeding structure extends across the liquid reservoir such that liquid must flow through the liquid feeding structure when flowing through the liquid reservoir toward or away from the vaporising unit. This means that no liquid in the liquid reservoir can bypass the liquid feeding structure on its way to the vaporising unit.

[0028] During use can be understood to be a period where a user is interacting with the aerosol generative device; for example just before, during, or after inhaling the vapor generated by the device.

[0029] Increasing the length of a fluid flow path through the liquid reservoir can be understood to mean that the flow path of the vaporisable liquid through the liquid reservoir no longer follows the path it would have if there were no liquid feeding structure in the reservoir. Specifically, the liquid feeding structure is arranged such that liquid must follow an indirect route through the reservoir. In this way, the new fluid flow path is substantially longer and therefore a liquid particle takes longer to move through the liquid reservoir.

[0030] The diffusion rate, as used throughout, is a function of the concentration difference from the wick to the furthest away section of the liquid reservoir from the wick divided by the length over which the moisture needs to diffuse to get between the two. As the flow path has been extended it can be seen that the diffusion rate is reduced. As previously discussed, this results in a reduced rate of volume increase of the vaporisable liquid and therefore a mitigation in leakage of vaporisable liquid.

[0031] Fluid flow path can be understood to mean the general movement of liquid particles, both as a general movement and as the movement of certain particle from areas of high concentration to low concentration.

[0032] It is important to note that the fluid path can be seen as flowing in two directions. Firstly, as occurs in devices with or without a liquid feeding structure, there is a general fluid flow of the liquid through the liquid reservoir towards the vaporising unit, usually due to gravity and the capillary action of features such as wicks. In other words, there is a first flow direction out of the liquid reservoir. The second direction of flow, which also occurs in devices with or without a liquid feeding structure, which is the flow of the absorbed water from the air-interface, often the wick, which flows into the liquid reservoir. In other words, there is a general fluid flow of absorbed water into the liquid reservoir. The absorption fluid flow occurs due to a negative concentration gradient which has the effect of drawing, or absorbing, the water further into the liquid reservoir where the water concentration is the lowest and the vaporising agent concentration is greatest. However, both fluid flows follow the same fluid flow path, they merely travel in opposite directions.

[0033] Preferably, the vaporiser further comprises a wick in fluid communication with the liquid reservoir, wherein the liquid feeding structure is arranged so as to reduce a rate of diffusion of moisture from the wick into the reservoir. The term moisture used herein can alternatively be known as liquid or water. This is achieved by the provision of an extended liquid flow path through the liquid feeding structure and the provision of a plurality of compartments.

[0034] A wick is a material which is configured such that provides a steady supply of vaporisable liquid from the liquid reservoir, and therefore through the liquid feeding structure, to a heating element using capillary action where it is vaporised. The wick is preferably made of cotton, ceramic, or a metal mesh.

[0035] Preferably, the liquid feeding structure is arranged so as to reduce a rate of diffusion of liquid from the wick into the reservoir via one end of the liquid feeding structure being positioned adjacent to an interface between the wick and the liquid reservoir. This is achieved by the provision of the extended liquid flow path through the liquid feeding structure and provision of a plurality of compartments. One end of the liquid feeding structure can be understood to mean a section of the liquid feeding structure which comprises an opening allowing liquid communication from outside the liquid feeding structure into the liquid feeding structure. Preferably, the liquid feeding structure has two ends allowing for flow into and out of the liquid feeding structure.

[0036] Therefore, as the liquid feeding structure is substantially adjacent to the interface between the wick and the liquid reservoir its ability to reduce the rate of water absorption into the liquid reservoir is increased. This is because in this embodiment the air-to-vapourisable liquid interface occurs adjacent to the liquid feeding structure and therefore a diffusion flow path into the liquid reservoir is effectively immediately extended starting from the air-to-vapourisable liquid interface.

[0037] Preferably, the liquid feeding structure of the vaporiser is arranged to provide a curved liquid flow path through the liquid reservoir. A curved flow path can be understood to be one which undertakes one or more turns in direction. In this way, the length of a fluid flow path through the liquid reservoir is increased.

[0038] In a further preferable implementation, the liquid feeding structure is arranged to provide a winding liquid flow path through the liquid reservoir. A winding liquid flow path can be understood to be one which comprises a plurality of changes in direction but wherein the overall direction of the liquid flow remains substantially the same. In particular, the liquid feeding structure may provide a cascading liquid flow path. In this way, the length of a fluid flow path through the liquid reservoir is increased.

[0039] Preferably, the liquid feeding structure comprises protrusions extending inwardly from an internal wall of the liquid reservoir. This allows for the flow path of the liquid to be altered in a simple and easily manufactured way. This embodiment is particularly easy and inexpensive to manufacture as the protrusions extend inwardly from an internal wall of the liquid reservoir and therefore support from within the device is not required.

[0040] Protrusions extending inwardly from an internal wall of the liquid reservoir can be understood to mean that the protrusions are attached to the internal wall of the liquid reservoir or, alternatively, protrusions extending inwardly from an internal wall of the liquid reservoir can be understood to mean that the protrusions are attached to the liquid feeding structure wherein the liquid feeding structure is adjacent the internal wall of the liquid reservoir. The first option requires the liquid feeding structure to be integrated with an internal wall of the liquid reservoir.

[0041] A protrusion can be understood to be a structure which substantially extends from its surroundings creating an obstruction to liquid flow substantially perpendicular to the surface to which it extends from.

[0042] In a further preferable implementation, the protrusions extend from substantially opposite sides of the liquid reservoir such that the openings between neighbouring compartments are defined by the gaps between the end of the protrusion and the opposite internal wall of the liquid reservoir.

[0043] Substantially opposite sides of the liquid reservoir means that the protrusions do not have to be mirror images of one another, but will extend from their respective attached surfaces in a direction substantially towards one another.

[0044] Preferably, the liquid feeding structure comprises an opening providing a constricted passage for liquid to travel between two neighbouring compartments. Preferably, the openings are greater than or equal to 1 mm, but less than 10 mm. Furthermore, the openings are preferably greater than or equal to 1 mm but less than 5mm. Further still, the openings are preferably between 1 and 2 mm. Preferably this dimension relates to the largest dimension of the opening.

[0045] The opening providing a constricted passage can be understood to mean that the opening is substantially smaller than the width of the aerosol generative device.

[0046] Preferably, the vaporiser further comprises a plurality of openings, each opening providing a passage between neighbouring compartments, wherein the plurality of openings are laterally displaced to prevent a direct fluid flow path through the liquid feeding structure.

[0047] Laterally displaced can be understood to mean that the openings do not overlap and are substantially apart from one another in a direction perpendicular to the length of the aerosol generative device. Therefore, as the absorbed water moves through the aerosol generative device, the flow is required to change direction each time it needs to go from one opening to another.

[0048] Preventing a direct flow path can be understood to mean that the flow cannot flow through the aerosol generative device without changing course at least once, and the flow path is substantially different to what the flow path would have been without the presence of a liquid feeding structure.

[0049] In a further preferable implementation, the compartments provide a cascading route for the liquid in the liquid reservoir to the vaporising unit.

[0050] Cascading can be understood to mean that the fluid flowing through the compartments moves from one to another in a sequential and flowing manner such that no compartment is missed. This results in each compartment having a lower water concentration than the previous in a direction moving away from the vaporising unit into the liquid reservoir.

[0051] Preferably, the vaporiser comprises a mouthpiece section which comprises an opening for the user to inhale the vapor from and a vaporising chamber wherein the vapor is formed during use.

[0052] Preferably, the liquid feed structure comprises a first part and a second part, the first and second parts configured to connect along a longitudinal interface to enclose the vaporising unit within.

[0053] This allows for the liquid feeding structure to be easily manufactured and assembled in a cost-effective manner.

[0054] In a further preferable implementation, the liquid feeding structure comprises protrusions extending inwardly from an internal wall of the liquid feeding structure, with one or more protrusions extending from the first part of the liquid feeding structure and one or more opposing protrusions extending from the second part of the liquid feeding structure, wherein openings between neighbouring compartments are defined by a gap between the end of a protrusion and the opposite internal wall of the liquid feeding structure.

[0055] This allows for the liquid feeding structure which extends a flow path of the vaporisable liquid to be easily manufactured and assembled in a cost-effective manner.

[0056] In a second aspect, a method of manufacturing a vaporiser for an aerosol generative device is provided. The method comprises providing a vaporising unit and a liquid reservoir, wherein the liquid reservoir is in fluid communication with the vaporising unit in use. The method further comprises forming a liquid feeding structure around the vaporising unit within the liquid reservoir, wherein the liquid feeding structure defines two or more compartments within the liquid reservoir which are in fluid communication, the two or more compartments are arranged such that liquid in the liquid reservoir flows sequentially through the two or more compartments when flowing towards or away from the vaporising unit during use, and wherein the liquid feeding structure is arranged so as to increase the length of a fluid flow path through the liquid reservoir.

[0057] Preferably, the method also comprises the liquid feeding structure being formed of two longitudinal sections which are moulded separately and then joined together around the vaporising unit to form the liquid feeding structure.

[0058] In a further preferably implementation, the moulding is injection moulding, and the joining is undertaken using ultrasonic welding.BRIEF DESCRIPTION OF DRAWINGS

[0059] Embodiments of the invention will now be described with reference to the figures, in which: Figure 1a illustrates a cross-section of a current vaporiser for an aerosol generative device wherein the cross-section includes the mouthpiece section; Figure 1b illustrates a cross-section of a current vaporiser for an aerosol-generating device wherein the cross-section is the X1-X1 cross section of Figure 1a so that it does not includes the mouthpiece section; Figure 2 illustrates a cross-section of a vaporiser for an aerosol generative device according to an embodiment of the current invention wherein the cross-section includes the mouthpiece section; Figure 3a illustrates a cross-section of a vaporiser, according to an embodiment of the invention, wherein the cross-section includes the mouthpiece section as the cross-section is cross-section Y-Y illustrated in Figure 2; Figure 3b illustrates a cross-section of a vaporiser, according to an embodiment of the invention, wherein the cross-section is the X2-X2 cross section of Figure 3a so that it does not include mouthpiece sections but does depict openings of the compartments; Figure 4a illustrates a cross-section of a vaporiser, according to an embodiment of the invention where the liquid feeding structure is integrated into the liquid reservoir wall, wherein the cross-section includes the mouthpiece section as the cross-section is cross-section Y-Y as illustrated in Figure 2; Figure 4b illustrates a cross-section of a vaporiser, according to an embodiment of the invention where the liquid feeding structure is integrated into the liquid reservoir wall, wherein the cross-section is the X2-X2 cross section of Figure 3a so that it does not include mouthpiece sections but does depict openings of the compartments; Figure 5 illustrates the liquid feeding structure separated in two halves as well as a vaporising unit; Figure 6 illustrates the method steps of manufacturing a vaporiser for an aerosol generative device. DETAILED DESCRIPTION

[0060] The present disclosure relates to a vaporiser for an aerosol generative device and a method of manufacture of said vaporiser.

[0061] Figures 1a and 1b illustrate two cross-sections of a current vaporiser 100 for an aerosol generative device. As can be seen, the vaporiser comprises a liquid reservoir (with walls 130, and an internal part for containing the vaporisable liquid 110), a mouthpiece section (with vaporising chamber wall 120), and a vaporising unit including a wick 150 and a heating coil 140.

[0062] The wick is arranged to transfer the vaporisable fluid from the liquid reservoir to the heating element via capillary action. As can be seen in Figure 1a, the wick is in direct contact with inside of the vaporising chamber and therefore, is in direct contact with atmospheric air. The atmospheric air contains water vapour, with the specific amount depending on the humidity of the air. The vaporising chamber well also have additional what content from the users breath. This means that the wake well absorbed water that is present in the vaporising chamber.

[0063] Vaporising agents such as propylene glycol and glycerin, which will be within the vaporisable liquid, are hygroscopic and absorb water. Therefore, at the air-wick there will be an absorption of water into the vaporisable liquid.

[0064] The water absorbed from the air can enter the liquid holding section via diffusion from the air-liquid interface. Importantly, the increase in water content in the vaporising liquid in turn results in an increase in the volume of the liquid.

[0065] As can be seen in Figure 1a, there is direct and uninhibited communication between the entire liquid reservoir and the wick, which in turn results in a quick diffusion of water absorbed in the wick into the liquid reservoir. Specifically, as there is open and unhindered communication between the wick and the liquid reservoir, the diffusion gradient of water into the vaporisable liquid is very high. In other words, at the wick there will be a high concentration of absorbed water, and at the end of the reservoir furthest from the wick there will be a low water concentration, and the unhindered communication between the two over a relatively large surface area means that there is a large diffusion mechanism. This results in the water absorbed in the wick to diffuse into the rest of the reservoir along numerous unhindered diffusion paths 160.

[0066] As can be seen from Figure 1b, the majority of the wick is in contact with the vaporisable liquid in the liquid reservoir and therefore has an unhindered diffusion path 160 for the water absorbed in the wick which is then further absorbed into the vaporising agents.

[0067] Turning now to embodiments of the invention, Figure 2 depicts a cut-through illustration of a vaporiser for an aerosol generative device according to the invention.

[0068] As can be seen from Figure 2, the vaporiser 200 comprises a mouthpiece section 320, a liquid reservoir 330, and a vaporising unit 340. The liquid reservoir 330 is the portion of the vaporiser which stores the vaporisable liquid before it is wicked away and vaporised. The vaporising unit may comprise a wick 250 and a heating element 240; the heating element 240 has not been labelled in Figure 2 for clarity. The wick 250 may be formed from cotton or ceramics, and in some situations can also be made from a metallic mesh. The heating element usually takes the form of a metallic wire coil wrapped around the wick 250, but is not limited to this embodiment. Generally, the wicking and heating functionality of the vaporiser can be undertaken by a number of different apparatuses which the skilled person would be aware of.

[0069] Importantly, the vaporiser also comprises a liquid feeding structure 270 comprising two or more compartments 290, 292, 294.

[0070] We now turn to Figures 3a and 3b, where the liquid feeding structure 270 can be seen more clearly.

[0071] Figure 3a illustrates a cross-section of a vaporiser wherein the cross-section includes the mouthpiece section as the cross-section is cross-section Y-Y illustrated in Figure 2.

[0072] As can be seen in Figure 3a, the liquid feeding structure 270 comprises a plurality of compartments 290, 292 and protrusions 280. It can be seen that the protrusions extend from an internal side of the liquid reservoir wall 210 and extend inwardly; this can be seen more easily in Figure 3b. Figure 3a demonstrates that the protrusions extend up to, and abut against, the vaporising chamber wall of a mouthpiece section 220. This results in compartments 290, 292 being formed which are substantially enclosed.

[0073] Figure 3b illustrates a cross-section of the same vaporiser as depicted in Figure 3a. In Figure 3b the cross-section is the X2-X2 cross section of Figure 3a and therefore does not depict features such as the vaporising chamber but does depict openings of the compartments.

[0074] Unlike in Figure 3a, in Figure 3b the openings 295 of the compartments 290, 292 can be seen. These openings allow for the liquid in the liquid reservoir to pass sequentially through each compartment in the liquid feeding structure on their flow path to the wick and in turn to be vaporised. These openings also force the water absorbed to flow through each compartment sequentially in such a manner that the absorption flow path 300 is extended.

[0075] In comparison to the flow paths 160 of conventional vaporisers depicted in Figure 1a and 1b, the flow path 300 of the vaporiser of this embodiment is substantial elongated. This can be seen via the length of the flow path 300 required to go between each compartment sequentially to as the water is absorbed progressively further into the liquid reservoir.

[0076] Turning specifically to the protrusion 280, as can be seen from Figures 3a and 3b, they extend from substantially opposite sides of the liquid reservoir walls such that the openings 295 between neighbouring compartments 290, 292 are defined by the gaps between the end of the protrusions 280 and the opposite internal wall of the liquid reservoir.

[0077] As can be seen, each opening 295 provides a passage between neighbouring compartments 290, 292 wherein the plurality of openings 295 are laterally displaced to prevent a direct fluid flow path 300 through the liquid feeding structure 270.

[0078] Figure 3b demonstrates what is meant by laterally displaced openings 295, as it can be seen that the openings 295 do not overlap and are substantially apart from one another in a direction perpendicular to the length of the aerosol generative device. Therefore, as the absorbed water moves through the aerosol generative device along a flow path 300, the flow is required to change direction each time it needs to go from one opening to another.

[0079] Preferably the openings are greater than or equal to 1 mm, but less than 10 mm, preferably less than 5mm, and further preferably the openings are between 1 mm and 2 mm. This allows for the vaporisable liquid to be wicked without significant hindrance while still sufficiently extending and hindering the water absorption flow path.

[0080] Figures 4a and 4b demonstrate another embodiment of the vaporiser 200 wherein the liquid feeding structure 270 is integrated into the liquid reservoir wall 210. Another difference in this embodiment compared to the one illustrated in Figures 3a and 3b is that this embodiment has compartments, and protrusions, extending throughout the entire liquid reservoir. Therefore, in the embodiment illustrated in Figure 4a and 4b, all of the liquid reservoir is compartmentalised into a plurality of compartments and there is no section of the liquid reservoir which is substantially devoid of the liquid feeding structure. In other words, in the embodiment illustrated in Figure 4a and 4b the liquid feeding structure extends throughout the entire liquid reservoir.

[0081] Figure 4a illustrates a cross-section of a vaporiser wherein the cross-section includes the mouthpiece section as the cross-section is cross-section Y-Y illustrated in Figure 2.

[0082] As can be seen in Figure 4a, the liquid feeding structure 270 comprises a plurality of compartments 290, 292 and protrusions 280. It can be seen that the protrusions extend from an internal side of the liquid reservoir wall 210 and extend inwardly; this can be seen more easily in Figure 3b. Figure 3a demonstrates that the protrusions extend up to, and abut against, the vaporising chamber wall of a mouthpiece section 220. This results in compartments 290, 292 being formed which are substantially enclosed.

[0083] Figure 4b illustrates a cross-section of the same vaporiser as depicted in Figure 3a. In Figure 4b the cross-section is the X2-X2 cross section of Figure 4a and therefore does not have features such as the vaporising chamber but does depict openings of the compartments.

[0084] Unlike in Figure 4a, in Figure 4b the openings 295 of the compartments 290, 292 can be seen. These openings allow for the liquid in the liquid reservoir to pass sequentially through each compartment in the liquid feeding structure on their flow path to the wick and in turn to be vaporised. These openings also force the water absorbed to flow through each compartment sequentially in such a manner that the absorption flow path 300 is extended.

[0085] In comparison to the flow paths 160 of conventional vaporisers depicted in Figure 1a and 1b, the flow path 300 of the vaporiser of this embodiment is substantial elongated. This can be seen via the length of the flow path 300 required to go between each compartment sequentially so that the water is absorbed progressively further into the liquid reservoir.

[0086] As can be seen from Figure 4b, the absorption path of the water 300 through the liquid feeding structure 270 is extended compared to what it would be without a liquid feeding structure, as can be seen by the diffusion paths 160 of Figure 1a and 1b. Furthermore, as the liquid feeding structure extends throughout the liquid reservoir the length of the flow path 300 in the vaporiser depicted in Figure 4a and 4b is longer than the vaporiser depicted in Figure 3a and 3b.

[0087] Turning to the protrusion 280 again, as could be seen from Figures 3a and 3b, it can also be seen in Figures 4a and 4b that the protrusions extend from substantially opposite sides of the liquid reservoir walls such that the openings 295 between neighbouring compartments 290, 292 are defined by the gaps between the end of the protrusions 280 and the opposite internal wall of the liquid reservoir.

[0088] Each opening 295 provides a passage between neighbouring compartments 290, 292 wherein the plurality of openings 295 are laterally displaced to prevent a direct fluid flow path 300 through the liquid feeding structure 270.

[0089] Figure 4b further aids to demonstrate what is meant by laterally displaced openings 295, as it can be seen that the openings 295 do not overlap and are substantially apart from one another in a direction perpendicular to the length of the aerosol generative device. Therefore, as the absorbed water moves through the aerosol generative device along a flow path 300, the flow is required to change direction each time it needs to go from one opening to another.

[0090] Figure 5 illustrates a preferable embodiment of the vaporiser wherein the liquid feeding structure is formed from the joining of two separately manufactured longitudinal sections 271, 272.

[0091] These two halves 271, 272 may be formed separately, via injection moulding for example, and be combined together. The two halves 271, 272 can be sealed together, to form an impermeable seal where required, via ultrasonic welding. Using ultrasonic welding is fast and efficient as it is completed in a few seconds, and also does not require consumables such as adhesives or fasteners.

[0092] As the protrusions are substantially opposite one another, they can form male-female mirrors of one another and therefore can easily form the compartment structure as required in a straightforward manufacturing way.

[0093] The number of protrusions is not limited in this application as long as there is at least one protrusion one each side of a half. As demonstrated in Figures 2 and 5 there are only two main protrusions extending inwardly from the outside liquid reservoir wall. However, as can be seen in Figures 3 and 4, there may be more protrusions and the total number is not limited in the application.

[0094] Figure 5 also demonstrates the two liquid reservoir sections 350, 360 present in each half 271, 272, and clearly demonstrates how they are formed via the presence of the vaporising chamber 225 in the middle. As is clear, when the two halves 271, 272 are joined the two liquid reservoir sections form two distinct and enclosed reservoir portions for storing the vaporisable liquid.

[0095] Figure 5 illustrates the vaporiser unit 245 as an entire unit and not sperate out into its potential components for ease of illustration.

[0096] Figure 6 illustrates the steps of manufacturing a vaporiser for an aerosol generative device, wherein the vaporiser takes the form of any of the embodiments discussed above in relation to Figures 2 to 5.

[0097] At step 601, providing a vaporising unit and a liquid reservoir, wherein the liquid reservoir is in fluid communication with the vaporising unit in use. The liquid feeding structure may be made using many different methods of manufacturing, such as injection moulding or 3D printing.

[0098] The liquid feeding structure may be made from plastic, such as a polycarbonate or polypropylene.

[0099] The liquid reservoir 230 and the vaporisable chamber 245 may also be made from plastic, such as a polycarbonate or polypropylene.

[0100] At step 602, forming a liquid feeding structure around the vaporising unit within the liquid reservoir, wherein the liquid feeding structure defines two or more compartments within the liquid reservoir which are in fluid communication, the two or more compartments are arranged such that liquid in the liquid reservoir flows sequentially through the two or more compartments when flowing towards or away from the vaporising unit during use, and wherein the liquid feeding structure is arranged so as to increase the length of a fluid flow path through the liquid reservoir.

[0101] The structural parts may be combined using ultrasonic sealing to form a watertight enclosure where appropriate. Using ultrasonic welding is fast and efficient as it is completed in a few seconds, and also does not require consumables such as adhesives or fasteners.

[0102] The liquid feeding structure can be designed such that the insertion of components of the vaporising unit is the same as, or similar to, how it would usually be done for a vaporiser without a liquid feeding structure.

Claims

1. A vaporiser for an aerosol generating device, the vaporiser comprising: a vaporising unit; a liquid reservoir, wherein the liquid reservoir is in fluid communication with the vaporising unit; a liquid feeding structure, wherein the liquid feeding structure defines two or more compartments within the liquid reservoir which are in fluid communication; and wherein the two or more compartments are arranged such that liquid in the liquid reservoir flows sequentially through the two or more compartments when flowing towards or away from the vaporising unit during use; and wherein the liquid feeding structure is arranged so as to increase the length of a fluid flow path through the liquid reservoir.

2. The vaporiser according to claim 1, wherein the vaporising unit comprises a wick in fluid communication with the liquid reservoir, wherein the liquid feeding structure is arranged so as to reduce a rate of diffusion of moisture from the wick into the reservoir.

3. The vaporiser according to claim 2, wherein one end of the liquid feeding structure is positioned adjacent to an interface between the wick and the liquid reservoir.

4. The vaporiser according to claims 1 to 3, wherein the liquid feeding structure is arranged to provide a curved liquid flow path through the liquid reservoir.

5. The vaporiser according to claim 4 wherein the liquid feeding structure is arranged to provide a winding liquid flow path through the liquid reservoir.

6. The vaporiser according to any of the proceeding claims, wherein the liquid feeding structure comprises protrusions extending inwardly from an internal wall of the liquid reservoir.

7. The vaporiser according to claim 6 wherein the protrusions extend from substantially opposite sides of the liquid reservoir so that the openings between neighbouring compartments are defined by the gap between the end of the protrusion and the opposite internal wall of the liquid reservoir.

8. The vaporiser according to any of the proceeding claims, wherein the liquid feeding structure comprises an opening providing a constricted passage for liquid to travel between two neighbouring compartments.

9. The vaporiser according to claim 7 or claim 8, further comprising a plurality of openings, each opening providing a passage between neighbouring compartments, wherein the plurality of openings are laterally displaced to prevent a direct fluid flow path through the liquid feeding structure.

10. The vaporiser according to any proceeding claim, wherein the compartments provide a cascading liquid flow path through the liquid reservoir to the vaporising unit.

11. The vaporiser according to any preceding claim wherein the liquid feed structure comprises a first part and a second part, the first and second parts configured to connect along a longitudinal interface to enclose the vaporising unit within.

12. The vaporiser according to claim 11 wherein the liquid feeding structure comprises protrusions extending inwardly from an internal wall of the liquid feeding structure, with one or more protrusions extending from the first part of the liquid feeding structure and one or more opposing protrusions extending from the second part of the liquid feeding structure, wherein openings between neighbouring compartments are defined by a gap between the end of a protrusion and the opposite internal wall of the liquid feeding structure.

13. An aerosol generative device, comprising the vaporiser of claims 1 to 12.

14. A method of manufacture of a vaporiser for an aerosol generating device, the method comprising: providing a vaporising unit and a liquid reservoir, wherein the liquid reservoir is in fluid communication with the vaporising unit in use; forming a liquid feeding structure around the vaporising unit within the liquid reservoir, wherein the liquid feeding structure defines two or more compartments within the liquid reservoir which are in fluid communication, the two or more compartments are arranged such that liquid in the liquid reservoir flows sequentially through the two or more compartments when flowing towards or away from the vaporising unit during use, and wherein the liquid feeding structure is arranged so as to increase the length of a fluid flow path through the liquid reservoir.

15. The method of claim 14, wherein the liquid feeding structure is formed of two longitudinal sections which are moulded separately and then joined together around the vaporising unit to form the liquid feeding structure.

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