Abstract
There is provided an aerosol generating system configured to heat an aerosol-forming substrate, the system including an aerosol generating device and a cartridge, a vaporizer configured to heat the aerosol-forming substrate to form an aerosol, at least one air inlet and at least one air outlet. The air inlet and the air outlet are arranged so as to define an air flow route between the air inlet and the air outlet. The aerosol generating system further includes a flow control configured to adjust a size of the at least one air inlet, so as to control an air flow speed in the air flow route.
Claims
1.-15. (canceled)
16. An aerosol generating system, comprising: an aerosol generating device in cooperation with a cartridge, the system being configured to heat an aerosol-forming substrate in the cartridge; a vaporizer configured to heat the aerosol-forming substrate to form an aerosol; at least one air inlet; at least one air outlet, the air inlet and the air outlet being arranged to define an air flow route between the air inlet and the air outlet; and flow control means for adjusting a size of the at least one air inlet, so as to control an air flow speed in the air flow route, wherein the flow control means comprises: a first member and a second member, the first and second members cooperating to define the at least one air inlet, wherein the first and second members are configured to rotate relative to one another so as to vary the size of the at least one air inlet, and wherein both the first member and the second member are contained in the cartridge.
17. The aerosol generating system according to claim 16, wherein the first member comprises at least one first aperture and the second member comprises at least one second aperture, the first and second apertures together forming the at least one air inlet, and wherein the first and second members are configured to rotate relative to one another so as to vary an extent of overlap of the first aperture and the second aperture so as to vary the size of the at least one air inlet.
18. The aerosol generating system according to claim 16, wherein the first member and the second member are rotatably and linearly moveable relative to one another so as to vary the size of the at least one air inlet.
19. The aerosol generating system according to claim 16, wherein the aerosol-forming substrate is a liquid aerosol-forming substrate.
20. The aerosol generating system according to claim 19, wherein the vaporizer of the aerosol generating system comprises a capillary wick configured to convey the aerosol-forming substrate by capillary action.
21. The aerosol generating system according to claim 16, wherein the aerosol generating system is electrically operated and the vaporizer of the aerosol generating system comprises an electric heater configured to heat the aerosol-forming substrate.
22. A cartridge, comprising; a storage portion configured to store an aerosol-forming substrate; a vaporizer configured to heat the aerosol-forming substrate; connection means allowing the cartridge to connect with an aerosol generating device; at least one air inlet being defined between the cartridge and the aerosol generating device: at least one air outlet, the air inlet and the air outlet being arranged to define an air flow route between the air inlet and the air outlet; and flow control means for adjusting a size of the at least one air inlet, so as to control an air flow speed in the air flow route, wherein the flow control means comprises: a first member and a second member, the first and second members cooperating to define the at least one air inlet, wherein the first and second members are configured to rotate relative to one another so as to vary the size of the at least one air inlet.
23. The cartridge according to claim 22, wherein the first member comprises at least one first aperture and the second member comprises at least one second aperture, the first and second apertures together forming the at least one air inlet, and wherein the first and second members are configured to rotate relative to one another so as to vary an extent of overlap of the first aperture and the second aperture so as to vary the size of the at least one air inlet.
24. The cartridge according to claim 22, wherein the aerosol-forming substrate is a liquid aerosol-forming substrate, and wherein the vaporizer comprises a capillary wick configured to convey the liquid aerosol-forming substrate by capillary action.
25. The cartridge according to claim 22, wherein the vaporizer comprises an electric heater configured to heat the aerosol-forming substrate, the electric heater being connectable to an electric power supply.
26. A method for varying air flow speed in an aerosol generating system comprising an aerosol generating device in cooperation with a cartridge, the aerosol generating system comprising a vaporizer configured to heat an aerosol-forming substrate in the cartridge to form an aerosol, at least one air inlet defined between the cartridge and the aerosol generating device, and at least one air outlet, the air inlet and the air outlet being arranged to define an air flow route between the air inlet and the air outlet, the method comprising rotating a first member of the cartridge relative to a second member of the cartridge to adjust a size of the at least one air inlet, so as to vary an air flow speed in the air flow route.
27. The method according to claim 26, wherein the first member comprises at least one first aperture and the second member comprises at least one second aperture, the first and second apertures together forming the at least one air inlet, and wherein the first and second members are configured to rotate relative to one another so as to vary an extent of overlap of the first aperture and the second aperture so as to vary the size of the at least one air inlet.
Description
[0061] The invention will be further described, by way of example only, with reference to the accompanying drawings, of which:
[0062] FIG. 1 shows an embodiment of an aerosol generating system according to the invention;
[0063] FIG. 2 is a perspective view of a portion of an aerosol generating system according to the invention, showing the air inlets in more detail;
[0064] FIG. 3 is a graph showing resistance to draw as a function of airflow path cross section in an aerosol generating system;
[0065] FIG. 4 is a graph showing the effect of air flow rate on aerosol droplet size for a given aerosol-forming substrate in an aerosol generating system; and
[0066] FIG. 5 is a graph showing the effect of air flow rate on aerosol droplet size for two alternative aerosol-forming substrates in an aerosol generating system.
[0067] FIG. 1 shows one example of an aerosol generating system according to the invention. In FIG. 1, the system is an electrically operated smoking system having a storage portion. The smoking system 101 of FIG. 1 comprises a cartridge 103 and a device 105. In the device 105, there is provided an electric power supply in the form of battery 107 and electric circuitry in the form of hardware 109 and puff detection system 111. In the cartridge 103, there is provided a storage portion 113 containing liquid 115, a capillary wick 117 and a vaporizer in the form of heater 119. Note that the heater is only shown schematically in FIG. 1. In the exemplary embodiment shown in FIG. 1, one end of capillary wick 117 extends into liquid storage portion 113 and the other end of capillary wick 117 is surrounded by the heater 119. The heater is connected to the electric circuitry via connections 121, which may pass along the outside of liquid storage portion 113 (not shown in FIG. 1). The cartridge 103 and the device 105 each include apertures which, when the cartridge and device are assembled together, align to form air inlets 123. Flow control means (to be described further with reference to FIGS. 2 to 5) are provided, allowing the size of the air inlets 123 to be adjusted. The cartridge 103 further includes an air outlet 125, and an aerosol forming chamber 127. The air flow route from the air inlets 123 through the aerosol forming chamber 127 to the air outlet 125 is shown by the dotted arrows.
[0068] In use, operation is as follows. Liquid 115 is conveyed by capillary action from the liquid storage portion 113 from the end of the wick 117 which extends into the liquid storage portion to the other end of the wick which is surrounded by heater 119. When a user draws on the aerosol generating system at the air outlet 125, ambient air is drawn through air inlets 123 as shown by the dotted arrows. In the arrangement shown in FIG. 1, the puff detection system 111 senses the puff and activates the heater 119. The battery 107 supplies electrical energy to the heater 119 to heat the end of the wick 117 surrounded by the heater. The liquid in that end of the wick 117 is vaporized by the heater 119 to create a supersaturated vapour. At the same time, the liquid being vaporized is replaced by further liquid moving along the wick 117 by capillary action. (This is sometimes referred to as pumping action.) The supersaturated vapour created is mixed with and carried in the air flow from the air inlets 123. In the aerosol forming chamber 127, the vapour condenses to form an inhalable aerosol, which is carried towards the outlet 125 and into the mouth of the user.
[0069] In the embodiment shown in FIG. 1, the hardware 109 and puff detection system 111 are preferably programmable. The hardware 109 and puff detection system 111 can be used to manage the aerosol generating system operation.
[0070] FIG. 1 shows one example of an aerosol generating system according to the present invention. Many other examples are possible, however. The aerosol generating system simply needs to comprise an aerosol generating device and a cartridge and to include a vaporizer for heating the aerosol-forming substrate to form an aerosol, at least one air inlet, at least one air outlet, and flow control means (to be described below with reference to FIGS. 2 to 5) for adjusting the size of the at least one air inlet so as to control the air flow speed in the air flow route from the air inlet to the air outlet. For example, the system need not be electrically operated. For example, the system need not be a smoking system. For example, the aerosol-forming substrate need not be a liquid aerosol-forming substrate. Moreover, even if the aerosol-forming substrate is a liquid aerosol-forming substrate, the system may not include a capillary wick. In that case, the system may include another mechanism for delivering liquid for vaporization. In addition, the system may not include a heater, in which case another device may be included to heat the aerosol-forming substrate. For example, a puff detection system need not be provided. Instead, the system could operate by manual activation, for example the user operating a switch when a puff is taken. For example, the overall shape and size of the aerosol generating system could be altered.
[0071] As discussed above, according to the invention, the aerosol generating system includes flow control means for adjusting the size of the at least one air inlet, so as to control the air flow speed in the air flow route through the aerosol generating system. An embodiment of the invention, including the flow control means, will now be described with reference to FIGS. 2 to 5. The embodiment is based on the example shown in FIG. 1, although is applicable to other embodiments of aerosol generating systems Note that FIGS. 1 and 2 are schematic in nature. In particular, the components shown are not necessarily to scale either individually or relative to one another.
[0072] FIG. 2 is a perspective view of a portion of the aerosol generating system of FIG. 1, showing in more detail the air inlets 123. FIG. 2 shows the cartridge 103 of the aerosol generating system 101 assembled with the device 105 of the aerosol generating system 101. The cartridge 103 and the device 105 each include apertures which, when the cartridge and device are assembled together, align or partially align to form air inlets 123.
[0073] In use, the cartridge 103 and the device 105 may be rotated relative to one another as shown by the arrow. The extent of overlap of the sets of apertures in the cartridge 103 and in the device 105 defines the size of the air inlets 123. The size of the air inlets 123 influences the velocity of the air flow through the aerosol generating system 101, which, in turn, affects the droplet size in the aerosol. This will be described further with reference to FIGS. 3 to 5.
[0074] FIG. 3 is a graph showing resistance to draw (pressure drop in Pascals (Pa)) as a function of airflow path cross section (mm.sup.2) in an aerosol generating system. As can be seen in FIG. 3, the pressure drop increases as the airflow path cross section decreases. (Note that the relationship shown in FIG. 3 is for a given flow rate, which is a combination of the puff duration and the puff volume.) The relationship between the pressure drop dP and the air flow path cross sectional area S.sup.2 follows an inverse parabolic relationship of the form dP=a/S.sup.2, where a is a constant. Thus, rotating the device 105 and the cartridge 103 relative to one another to increase the size of the air inlets 123 in the aerosol generating system increases the cross sectional area of the air flow path, which decreases the pressure drop or resistance to draw. Rotating the device 105 and the cartridge 103 relative to one another to decrease the size of the air inlets 123 in the aerosol generating system decreases the cross sectional area of the air flow path, which increases the pressure drop or resistance to draw.
[0075] As already mentioned, the size of the air inlets 123 influences the velocity of the air flow through the aerosol generating system 101. This, in turn, affects the droplet size in the aerosol as will now be described. It is known in the art that increasing the cooling rate in an aerosol generating system decreases the mean droplet size in the resulting aerosol. The cooling rate is a combination of the temperature gradient between the vaporizer and the surrounding temperature and the velocity of the air flow local to the vaporizer. The temperature gradient is determined and fixed by the ambient conditions, so the cooling rate is primarily driven by the local airflow velocity through the aerosol generating system, in particular through the aerosol forming chamber in the locality of the vaporizer. Thus, adjusting the airflow velocity through the aerosol forming chamber of the aerosol generating system enables generation of different types of aerosols for a given aerosol-forming substrate.
[0076] FIG. 4 is a graph showing the effect of air flow rate (litres per minute) on aerosol droplet size (microns) for a given aerosol-forming substrate in an aerosol generating system. It can be seen from FIG. 4 that increasing the air flow rate through the aerosol generating system decreases the mean aerosol droplet size. In contrast, decreasing the air flow rate through the aerosol generating system increases the mean droplet size in the resulting aerosol.
[0077] Two points on the curve of FIG. 4, A and B, have been labelled. State A has a relatively low air flow rate through the aerosol generating system, resulting in a relatively large mean droplet size in the resulting aerosol. This corresponds to a relatively large cross sectional area of the air flow path, which results in a relatively low resistance to draw, and hence a relatively low air flow rate. Thus, state A corresponds to the device 105 and the cartridge 103 of the aerosol generating system (see FIGS. 1 and 2) being rotated relative to one another so as to result in a relatively large overlap between the apertures in the device 105 and the cartridge 103. This results in a relatively large air inlet 123, for example 100% of the maximum air inlet size. In contrast, state B has a relatively high air flow rate through the aerosol generating system, resulting in a relatively small mean droplet size in the resulting aerosol. This corresponds to a relatively small cross sectional area of the air flow path, which results in a relatively high resistance to draw and hence a relatively high air flow rate. Thus, state B corresponds to the device 105 and the cartridge 103 of the aerosol generating system being rotated relative to one another so as to result in a relatively small amount of overlap between the apertures in the device 105 and the cartridge 103. This results in a relatively small air inlet 123, for example 40% of the maximum air inlet size.
[0078] As shown in FIG. 4, the present invention allows the size of the at least one air inlet to be adjusted so as to control the air flow speed in the air flow route. This enables the generation of different sorts of aerosols (that is aerosols with different mean droplet sizes and droplet size distributions) for a given aerosol-forming substrate.
[0079] Alternatively, adjusting the airflow velocity through the aerosol forming chamber of the aerosol generating system allows a desired aerosol droplet size to be produced for a variety of aerosol-forming substrates. FIG. 5 is a graph showing the effect of air flow rate (litres per minute) on aerosol droplet size (microns) for two alternative aerosol-forming substrates 501, 503 in an aerosol generating system. As in FIG. 4, for both aerosol-forming substrates 501 and 503, increasing the air flow rate through the aerosol generating system decreases the mean aerosol droplet size and decreasing the air flow rate through the aerosol generating system increases the mean aerosol droplet size. For a given air flow rate, aerosol-forming substrate 501 results in a smaller mean aerosol droplet size than aerosol-forming substrate 503.
[0080] Two points A and B have been labelled in FIG. 5. A is on the curve for aerosol-forming substrate 501. B is on the curve for aerosol-forming substrate 503. At A and B the resulting mean aerosol droplet size is equal. For state A, because of the properties of aerosol-forming substrate 501, the air flow rate which results in that mean aerosol droplet size is relatively low. This corresponds to a relatively large cross sectional area of the air flow path, which results in a relatively low resistance to draw, and hence a relatively low air flow rate. Thus, state A corresponds to the device 105 and the cartridge 103 of the aerosol generating system (see FIGS. 1 and 2) being rotated relative to one another so as to result in a relatively large overlap between the apertures in the device 105 and the cartridge 103. This results in a relatively large air inlet 123, for example 100% of the maximum air inlet size. For state B, however, because of the properties of aerosol-forming substrate 503, the air flow rate which results in that mean aerosol droplet size is relatively high. This corresponds to a relatively small cross sectional area of the air flow path, which results in a relatively high resistance to draw, and hence a relatively high air flow rate. Thus, state B corresponds to the device 105 and the cartridge 103 of the aerosol generating system being rotated relative to one another so as to result in a relatively small overlap between the apertures in the device 105 and the cartridge 103. This results in a relatively small air inlet 123, for example 40% of the maximum air inlet size.
[0081] As shown in FIG. 5, the present invention allows the size of the at least one air inlet to be adjusted so as to control the air flow speed in the air flow route. This enables the generation of a desired aerosol (that is having the desired mean droplet size and droplet size distribution) for a variety of aerosol-forming substrates.
[0082] In the described embodiment, rotation of the device 105 and the cartridge 103 relative to one another provides flow control means which allows the pressure drop at the air inlets 123 to be adjusted. This affects the speed of the air flow through the aerosol generating system. The air flow speed affects the mean droplet size and the droplet size distribution in the aerosol, which may in turn affect the experience for the user. Thus, the flow control means allows the resistance to draw (that is pressure drop at the air inlet) to be adjusted, for example according to user preference. In addition, for a given aerosol-forming substrate, the flow control means allows a range of mean aerosol droplet sizes to be produced, and the desired aerosol may be selected by a user according to the user's preference. Also, the flow control means allows a particular desired mean aerosol droplet size to be produced for a selection of aerosol-forming substrates. Thus, the flow control means allows the aerosol generating system to be compatible with a variety of different aerosol-forming substrates and the flow control means allows the user to select the desired aerosol properties for a number of different compatible aerosol-forming substrates.
[0083] In FIG. 2, the flow control means is provided by rotation of the device 105 and the cartridge 103 of the aerosol generating system relative to one another. However, the flow control means need not be provided by cooperation of the two portions of the system. Flow control means may be provided in the device 105. Alternatively or additionally, flow control means may be provided in the cartridge 103. In fact, the aerosol generating system need not comprise a separate cartridge and device. In addition, in the FIG. 2 embodiment, the size of the air inlets 123 is adjusted by varying the extent of overlap of the apertures in the device 105 and in the cartridge 103. However, the flow control means need not be formed by overlap of two sets of apertures. The flow control means may be provided by any other suitable mechanism. For example, the flow control means may be provided by a single aperture having a moveable shutter to open and close the aperture. In addition, in the FIG. 2 embodiment, the device 105 and the cartridge 103 are rotatable relative to one another. However, alternatively, the device 105 and the cartridge 103 could be linearly moveable relative to one another, for example, by sliding. Alternatively, the device 105 and the cartridge 103 could be moveable relative to one another by a combination of rotational and linear movement, for example, by a screw thread. In addition, any suitable number, arrangement and shapes of apertures may be provided.
[0084] Thus, according to the invention, the aerosol generating system includes flow control means for adjusting the size of at least one air inlet so as to control the air flow speed in the air flow route through the aerosol generating system. Embodiments of the aerosol generating system and flow control means have been described with reference to FIGS. 2 to 5.
