Patent Application
20240407449
The present disclosure claims the benefit of priority from the following application(s), the entire contents of which are hereby incorporated by reference:
The present invention relates to a smoking substitute apparatus and, in particular, a smoking substitute apparatus that is able to deliver nicotine to a user in an effective manner.
The smoking of tobacco is generally considered to expose a smoker to potentially harmful substances. It is thought that a significant amount of the potentially harmful substances are generated through the burning and/or combustion of the tobacco and the constituents of the burnt tobacco in the tobacco smoke itself.
Low temperature combustion of organic material such as tobacco is known to produce tar and other potentially harmful by-products. There have been proposed various smoking substitute systems in which the conventional smoking of tobacco is avoided.
Such smoking substitute systems can form part of nicotine replacement therapies aimed at people who wish to stop smoking and overcome a dependence on nicotine.
Known smoking substitute systems include electronic systems that permit a user to simulate the act of smoking by producing an aerosol (also referred to as a “vapour”) that is drawn into the lungs through the mouth (inhaled) and then exhaled. The inhaled aerosol typically bears nicotine and/or a flavourant without, or with fewer of, the health risks associated with conventional smoking.
In general, smoking substitute systems are intended to provide a substitute for the rituals of smoking, whilst providing the user with a similar, or improved, experience and satisfaction to those experienced with conventional smoking and with combustible tobacco products.
The use of smoking substitute systems has grown rapidly in the past few years as an aid to assist habitual smokers wishing to quit tobacco smoking. There are a number of different categories of smoking substitute systems, each utilising a different smoking substitute approach. Some smoking substitute systems are designed to resemble a conventional cigarette and are cylindrical in form with a mouthpiece at one end. Other smoking substitute devices do not generally resemble a cigarette (for example, the smoking substitute device may have a generally box-like form, in whole or in part).
One approach is the so-called “vaping” approach, in which a vaporisable liquid, or an aerosol former, sometimes typically referred to herein as “e-liquid”, is heated by a heating device (sometimes referred to herein as an electronic cigarette or “e-cigarette” device) to produce an aerosol vapour which is inhaled by a user. The e-liquid typically includes a base liquid, nicotine and may include a flavourant. The resulting vapour therefore also typically contains nicotine and/or a flavourant. The base liquid may include propylene glycol and/or vegetable glycerine.
A typical e-cigarette device includes a mouthpiece, a power source (typically a battery), a tank for containing e-liquid and a heating device. In use, electrical energy is supplied from the power source to the heating device, which heats the e-liquid to produce an aerosol (or “vapour”) which is inhaled by a user through the mouthpiece.
E-cigarettes can be configured in a variety of ways. For example, there are “closed system” vaping smoking substitute systems, which typically have a sealed tank and heating element. The tank is pre-filled with e-liquid and is not intended to be refilled by an end user. One subset of closed system vaping smoking substitute systems include a main body which includes the power source, wherein the main body is configured to be physically and electrically couplable to a consumable including the tank and the heating element. In this way, when the tank of a consumable has been emptied of e-liquid, that consumable is removed from the main body and disposed of. The main body can then be reused by connecting it to a new, replacement, consumable. Another subset of closed system vaping smoking substitute systems are completely disposable, and intended for one-use only.
There are also “open system” vaping smoking substitute systems which typically have a tank that is configured to be refilled by a user. In this way the entire device can be used multiple times.
An example vaping smoking substitute system is the myblu™ e-cigarette. The myblu™ e-cigarette is a closed system which includes a main body and a consumable. The main body and consumable are physically and electrically coupled together by pushing the consumable into the main body. The main body includes a rechargeable battery. The consumable includes a mouthpiece and a sealed tank which contains e-liquid. The consumable further includes a heater, which for this device is a heating filament coiled around a portion of a wick. The wick is partially immersed in the e-liquid, and conveys e-liquid from the tank to the heating filament. The system is controlled by a microprocessor on board the main body. The system includes a sensor for detecting when a user is inhaling through the mouthpiece, the microprocessor then activating the device in response. When the system is activated, electrical energy is supplied from the power source to the heating device, which heats e-liquid from the tank to produce a vapour which is inhaled by a user through the mouthpiece.
For a smoking substitute system it is desirable to deliver nicotine into the user's lungs, where it can be absorbed into the bloodstream. However, the present disclosure is based in part on a realisation that some prior art smoking substitute systems, such delivery of nicotine is not efficient. In some prior art systems, the aerosol droplets have a size distribution that is not suitable for delivering nicotine to the lungs. Aerosol droplets of a large particle size tend to be deposited in the mouth and/or upper respiratory tract. Aerosol particles of a small (e.g. sub-micron) particle size can be inhaled into the lungs but may be exhaled without delivering nicotine to the lungs. As a result the user would require drawing a longer puff, more puffs, or vaporising e-liquid with a higher nicotine concentration in order to achieve the desired experience.
It is of interest to allow the user of a smoking substitute system a degree of control over the aerosol particle size inhaled, in part to take advantage over the phenomena reported above concerning the effect of aerosol particle size on the deposition location within the user's respiratory system.
The present disclosure has been devised in the light of the above considerations. In particular, by provision of suitable air flow with bypasses the aerosol generator/vaporisation chamber, the aerosol characteristics can be more easily controlled to desired (for example) particle size.
In a general aspect, then, the present invention provides a smoking substitute apparatus in which some or all of the air flow through the apparatus bypasses the aerosol generation chamber; this bypass air flow passes through a holder which holds the aerosol generator itself.
That is, the invention provides a smoking substitute apparatus having an aerosol generator comprises a holder which retains a heatable wick, the holder having a bypass inlet air flow passage extending through and within it, such that air running through the bypass inlet air flow passage does not enter the aerosol generator, in particular the region around the heatable wick.
In a first aspect, the present invention provides a smoking substitute apparatus for delivery of an aerosol to a user drawing air through the apparatus, the apparatus comprising: a housing defining a tank for holding a reservoir of an aerosol precursor; an air inlet; an outlet; at least one air flow path between the air inlet and the outlet, the air flow path extending in a upstream to downstream direction; an aerosol generator disposed in the apparatus for generating an aerosol from the aerosol precursor for entrainment in an air flow along the air flow path defined at least in part by an outlet air flow passage, downstream of the aerosol generator; wherein the aerosol generator comprises a holder which retains a heatable wick, at least one end of the heatable wick being in fluid communication with aerosol precursor in the tank via an opening in the holder; wherein the holder is sealed with respect to the housing and the outlet air flow passage in order to retain the aerosol precursor in the tank; wherein the air inlet connects to at least one bypass inlet air flow passage provided through and within the holder, the bypass air inlet passage extending from an upstream end of the holder to a downstream end of the holder, air flow through the bypass inlet air flow passage bypassing the aerosol generator and passing along the outlet air flow passage, downstream of the aerosol generator.
This configuration brings bypass air flow through the holder, the bypass inlet air flow passage being provided within the holder. This simplifies construction of the apparatus. Furthermore, it will be recognised that the coil holder is a critical component of the apparatus, responsible to holding the wick, coil or other heater. It may protect or hold electrical connections and is often responsible for enclosing the aerosol generator. Other components of the apparatus such as an air gasket or a tank gasket may be seated on the holder. (These gaskets may prevent aerosol precursor from leaking out of the tank around the holder.) Providing the bypass air inlet passage or passages through and within the holder (rather than around it) ensures that no additional components are needed in order to ensure suitable sealing of those passages by, for example, the tank gasket and air gasket.
In some embodiments, the smoking substitute apparatus further comprises at least one main inlet air flow passage provided through the holder, the main inlet air flow passage extending from an upstream end of the holder to the aerosol generator. That is, in some embodiments there are multiple passages through the holder; firstly the at least one bypass inlet air flow passage(s), and secondly the at least one main inlet air flow passage(s).
The holder may advantageously provide a vaporisation chamber, containing the heatable wick, and bounding the vaporisation chamber such that the vaporisation chamber is separated from the bypass inlet air flow passage(s) by interior walls of the holder. In such embodiments the holder extends, and therefore so does the bypass inlet air flow passage(s), to a position downstream of the vaporisation chamber (that is, beyond the vaporisation chamber), and therefore the heatable wick, to enable the clear bypassing of the bypass air flow. In this way the vapour/aerosol generated by the heatable wick is not perturbed by the bypass air too soon.
The holder may substantially (or fully) define the vaporisation chamber, and thus may form an enclosure within which the heatable wick is held. In this respect, the holder may surround the vaporisation chamber, e.g. in an annular arrangement around the vaporisation chamber.
It is useful to have the bypass inlet air passage(s) opening into the same space as the main inlet air flow passage(s). For example, a puff sensor in the main body or the apparatus ‘sees’ (that is, senses) the air pressure change associated with both the bypass inlet air flow as well as the main inlet air flow. This can ensure that the puff sensor operates correctly to heat the coil at the start of inhalation.
Accordingly, the entry points of the bypass inlet air passage(s) and the main inlet air flow passage(s) are advantageously provided on the same face surface of the holder. Suitably that is an upstream end outer surface face of the holder.
The air flow passage(s) through the holder are suitably connected to the exterior of the apparatus by one or more connecting passages to enable air flow into the apparatus, through the connecting passages to the air flow passage(s). The air inlet (to the exterior of the apparatus) may lead to passages corresponding to the main or bypass inlet air flow passages; alternatively, the connecting passage may be shared to provide a common air flow from the exterior to all the air flow passages (bypass or main) present.
Thus, in some embodiments, the at least one main inlet air flow passage extends from a main air inlet to the aerosol generator, and the at least one bypass inlet air flow passage extends from the air inlet to the downstream end of the holder. In each case the connecting passages mentioned above form part of the main inlet air flow passage and bypass inlet air flow passage. It may be the case that on the exterior of the apparatus there are one or more of the air inlets, which act as both main and bypass air inlets, linked by one or more connecting passages (which may correspond to sections of both the main inlet air flow passage(s) and the bypass inlet air flow passage(s)) to a space from which each bypass inlet air flow passage and main inlet air flow passage present extends through the holder. It is noted that this ‘space’ need not have any particular size; indeed, it may be no bigger than (and effectively a continuation of) the air flow passages to which it is linked.
There may be multiple bypass inlet air flow passages provided through and within the holder, each extending from an upstream end of the holder to a downstream end of the holder, and air flow through each bypass inlet air flow passage bypassing the aerosol generator and passing along the outlet air flow passage, downstream of the aerosol generator. This may give a preferred level of splitting of air flow between the bypass inlet air flow passages, leading to advantageous airflow within the apparatus. Where one or more main inlet air flow passages through the holder are present, the size and number of the bypass and main inlet air flow passages may be adjusted to give a preferred ratio of air flow between them.
Where there are multiple bypass inlet air flow passages, it may be preferred that they are provided circumferentially around the aerosol generator. They may optionally be equally spaced around the aerosol generator. This helps with even air flow and air flow utilisation, and reduces the chance of blockage or other failure leading to a problem.
When multiple bypass inlet air flow passages are provided within the holder, they may suitably be separate. That is, each such passage extends from a different place on the upstream end of the holder to a respective different place on the downstream end of the holder. The multiple bypass air flow passages are thus separate within the holder, and do not meet or join, or indeed branch or otherwise split, therein. This makes manufacturing straightforward.
In some embodiments, the main air inlet and the air inlet are a single inlet and the main inlet air flow passage and at least one bypass inlet air flow passage extend as a single passage from the single inlet to the upstream end of the holder. There may be more than one such single inlet. That is, the apparatus may comprise, as mentioned above, multiple air inlets on its exterior, each linked by a connecting passage to a space at the upstream end of the holder. From there, the individual bypass inlet air flow passage(s), and main inlet air flow passage(s) if present, extend through the holder.
For manufacturing reasons it may be preferred that the holder is a monolithic, and for example moulded, component.
The present invention also includes a smoking substitute apparatus as described above, wherein the apparatus is adapted to engage with a main body to form a smoking substitute system, the main body comprising a pressure sensor sensitive to pressure in the smoking substitute system immediately upstream of the holder (for example, between the holder and the air inlet or main air inlet, within one of the connecting passages), the pressure sensor being adapted to energise the aerosol generator when a pressure change is detected corresponding to an inhalation event. The pressure sensor may, for example, be position in the space upstream of the holder from which the various bypass and main inlet air flow passages extend through the holder. Or it may be positioned upstream of that space, for example in a passage connecting the air inlet or main air inlet to the bypass inlet air flow passage and/or main inlet air flow passage.
Such a smoking substitute system, comprising a smoking substitute apparatus of the present invention and a main body as described herein, also forms an aspect of the present invention.
In more detail, the smoking substitute apparatus may be comprised by or within a cartridge configured for engagement with the main body, the cartridge and main body together forming a smoking substitute system. The smoking substitute apparatus may be removably engageable with the main body (which may also be referred to herein as the base unit).
The smoking substitute apparatus may be in the form of a consumable. The consumable may be configured for engagement with a main body. When the consumable is engaged with the main body, the combination of the consumable and the main body may form a smoking substitute system such as a closed smoking substitute system. For example, the consumable may comprise components of the system that are disposable, and the main body may comprise non-disposable or non-consumable components (e.g. power supply, controller, sensor, etc.) that facilitate the generation and/or delivery of aerosol by the consumable. In such an embodiment, the aerosol precursor (e.g. e-liquid) may be replenished by replacing a used consumable with an unused consumable.
Alternatively, the smoking substitute apparatus may be a non-consumable apparatus (e.g. that is in the form of an open smoking substitute system). In such embodiments an aerosol former (e.g. e-liquid) of the system may be replenished by re-filling, e.g. a reservoir of the smoking substitute apparatus, with the aerosol precursor (rather than replacing a consumable component of the apparatus).
In light of this, it should be appreciated that some of the features described herein as being part of the smoking substitute apparatus may alternatively form part of a main body for engagement with the smoking substitute apparatus. This may be the case in particular when the smoking substitute apparatus is in the form of a consumable.
Where the smoking substitute apparatus is in the form of a consumable, the main body and the consumable may be configured to be physically coupled together. For example, the consumable may be at least partially received in a recess of the main body, such that there is an interference fit between the main body and the consumable. Alternatively, the main body and the consumable may be physically coupled together by screwing one onto the other, or through a bayonet fitting, or the like.
Thus, the smoking substitute apparatus may comprise one or more engagement portions for engaging with a main body. In this way, one end of the smoking substitute apparatus may be coupled with the main body, whilst an opposing end of the smoking substitute apparatus may define a mouthpiece of the smoking substitute system.
The smoking substitute apparatus comprises a tank/reservoir configured to store an aerosol precursor, such as an e-liquid. The e-liquid may, for example, comprise a base liquid. The e-liquid may further comprise nicotine. The base liquid may include propylene glycol and/or vegetable glycerine. The e-liquid may be substantially flavourless. That is, the e-liquid may not contain any deliberately added additional flavourant and may consist solely of a base liquid of propylene glycol and/or vegetable glycerine and nicotine.
The reservoir may be in the form of a tank. At least a portion of the tank may be light-transmissive. For example, the tank may comprise a window to allow a user to visually assess the quantity of e-liquid in the tank. A housing of the smoking substitute apparatus may comprise a corresponding aperture (or slot) or window that may be aligned with a light-transmissive portion (e.g. window) of the tank. The reservoir may be referred to as a “clearomizer” if it includes a window, or a “cartomizer” if it does not.
The outlet may be at a mouthpiece of the smoking substitute apparatus. In this respect, a user may draw fluid (e.g. air) into and through the apparatus by inhaling at the outlet (i.e. using the mouthpiece). The air flow passage(s) of the present invention may be at least partially defined by the tank. The tank may substantially (or fully) define one or more of the passages, in particular the outlet air flow passage, for at least a part of the length of the passage. In this respect, the tank may surround the passage, e.g. in an annular arrangement around the passage. For example the tank may surround the outlet air flow passage.
The vaporisation chamber, which may be formed as a cavity within the holder, may be arranged to be in fluid communication with the air inlet and outlet (via the outlet air flow passage). The vaporisation chamber may be a portion downstream of a main inlet air flow passage. In this respect, the air as drawn in by the user may entrain the generated vapour in a flow away from the heatable wick and heater. The entrained vapour may form an aerosol in the vaporisation chamber, or it may form the aerosol further downstream. The vaporisation chamber may be at least partially defined by the tank.
In use, the user may puff on a mouthpiece of the smoking substitute apparatus, i.e. draw on the smoking substitute apparatus by inhaling, to draw in an air stream therethrough. The part of the air flow which bypasses the vaporisation chamber (bypass or dilution air flow) may combine with another part of the air flow (main air flow) for diluting the aerosol contained therein.
As a user puffs on the mouthpiece, vaporised e-liquid entrained in the passing air flow may be drawn towards the outlet via the outlet air flow passage. The vapour may cool, and thereby nucleate and/or condense along the outlet air flow passage to form a plurality of aerosol droplets, e.g. nicotine-containing aerosol droplets. A portion of these aerosol droplets may be delivered to and be absorbed at a target delivery site, e.g. a user's lung, whilst a portion of the aerosol droplets may instead adhere onto other parts of the user's respiratory tract, e.g. the user's oral cavity and/or throat. Typically, in some known smoking substitute apparatuses, the aerosol droplets as measured at the outlet of the passage, e.g. at the mouthpiece, may have a droplet size, d50, of less than 1 μm.
In some embodiments of the invention, the d50 particle size of the aerosol particles is preferably at least 1 μm, more preferably at least 2 μm. Typically, the d50 particle size is not more than 10 μm, preferably not more than 9 μm, not more than 8 μm, not more than 7 μm, not more than 6 μm, not more than 5 μm, not more than 4 μm or not more than 3 μm. It is considered that providing aerosol particle sizes in such ranges permits improved interaction between the aerosol particles and the user's lungs.
The particle droplet size, d50, of an aerosol may be measured by a laser diffraction technique. For example, the stream of aerosol output from the outlet of the passage may be drawn through a Malvern Spraytec laser diffraction system, where the intensity and pattern of scattered laser light are analysed to calculate the size and size distribution of aerosol droplets. As will be readily understood, the particle size distribution may be expressed in terms of d10, d50 and d90, for example. Considering a cumulative plot of the volume of the particles measured by the laser diffraction technique, the d10 particle size is the particle size below which 10% by volume of the sample lies. The d50 particle size is the particle size below which 50% by volume of the sample lies. The doo particle size is the particle size below which 90% by volume of the sample lies. Unless otherwise indicated herein, the particle size measurements are volume-based particle size measurements, rather than number-based or mass-based particle size measurements.
The spread of particle size may be expressed in terms of the span, which is defined as (d90−d10)/d50. Typically, the span is not more than 20, preferably not more than 10, preferably not more than 8, preferably not more than 4, preferably not more than 2, preferably not more than 1, or not more than 0.5.
The smoking substitute apparatus (or main body engaged with the smoking substitute apparatus) may comprise a power source. The power source may be electrically connected (or connectable) to a heater of the smoking substitute apparatus (e.g. when the smoking substitute apparatus is engaged with the main body). The power source may be a battery (e.g. a rechargeable battery). A connector in the form of e.g. a USB port may be provided for recharging this battery.
When the smoking substitute apparatus is in the form of a consumable, the smoking substitute apparatus may comprise an electrical interface for interfacing with a corresponding electrical interface of the main body. One or both of the electrical interfaces may include one or more electrical contacts. Thus, when the main body is engaged with the consumable, the electrical interface of the main body may be configured to transfer electrical power from the power source to a heater of the consumable via the electrical interface of the consumable.
The electrical interface of the smoking substitute apparatus may also be used to identify the smoking substitute apparatus (in the form of a consumable) from a list of known types. For example, the consumable may have a certain concentration of nicotine and the electrical interface may be used to identify this. The electrical interface may additionally or alternatively be used to identify when a consumable is connected to the main body.
Again, where the smoking substitute apparatus is in the form of a consumable, the main body may comprise an identification means, which may, for example, be in the form of an RFID reader, a barcode or QR code reader. This identification means may be able to identify a characteristic (e.g. a type) of a consumable engaged with the main body. In this respect, the consumable may include any one or more of an RFID chip, a barcode or QR code, or memory within which is an identifier and which can be interrogated via the identification means.
The smoking substitute apparatus or main body may comprise a controller, which may include a microprocessor. The controller may be configured to control the supply of power from the power source to the heater of the smoking substitute apparatus (e.g. via the electrical contacts). A memory may be provided and may be operatively connected to the controller. The memory may include non-volatile memory. The memory may include instructions which, when implemented, cause the controller to perform certain tasks or steps of a method.
The main body or smoking substitute apparatus may comprise a wireless interface, which may be configured to communicate wirelessly with another device, for example a mobile device, e.g. via Bluetooth®. To this end, the wireless interface could include a Bluetooth® antenna. Other wireless communication interfaces, e.g. WiFi®, are also possible. The wireless interface may also be configured to communicate wirelessly with a remote server.
A puff sensor may be provided that is configured to detect a puff (i.e. inhalation from a user). The puff sensor may be operatively connected to the controller so as to be able to provide a signal to the controller that is indicative of a puff state (i.e. puffing or not puffing). The puff sensor may, for example, be in the form of a pressure sensor or an acoustic sensor. That is, the controller may control power supply to the heater of the consumable in response to a puff detection by the sensor. The control may be in the form of activation of the heater in response to a detected puff. That is, the smoking substitute apparatus may be configured to be activated when a puff is detected by the puff sensor. When the smoking substitute apparatus is in the form of a consumable, the puff sensor may be provided in the consumable or alternatively may be provided in the main body.
The term “flavourant” is used to describe a compound or combination of compounds that provide flavour and/or aroma. For example, the flavourant may be configured to interact with a sensory receptor of a user (such as an olfactory or taste receptor). The flavourant may include one or more volatile substances.
The flavourant may be provided in solid or liquid form. The flavourant may be natural or synthetic. For example, the flavourant may include menthol, liquorice, chocolate, fruit flavour (including e.g. citrus, cherry etc.), vanilla, spice (e.g. ginger, cinnamon) and tobacco flavour. The flavourant may be evenly dispersed or may be provided in isolated locations and/or varying concentrations.
The present inventors consider that a flow rate of 1.3 L min−1 is towards the lower end of a typical user expectation of flow rate through a conventional cigarette and therefore through a user-acceptable smoking substitute apparatus. The present inventors further consider that a flow rate of 2.0 L min−1 is towards the higher end of a typical user expectation of flow rate through a conventional cigarette and therefore through a user-acceptable smoking substitute apparatus. Embodiments of the present invention therefore provide an aerosol with advantageous particle size characteristics across a range of flow rates of air through the apparatus.
The aerosol may have a Dv50 of at least 1.1 μm, at least 1.2 μm, at least 1.3 μm, at least 1.4 μm, at least 1.5 μm, at least 1.6 μm, at least 1.7 μm, at least 1.8 μm, at least 1.9 μm or at least 2.0 μm.
The aerosol may have a Dv50 of not more than 4.9 μm, not more than 4.8 μm, not more than 4.7 μm, not more than 4.6 μm, not more than 4.5 μm, not more than 4.4 μm, not more than 4.3 μm, not more than 4.2 μm, not more than 4.1 μm, not more than 4.0 μm, not more than 3.9 μm, not more than 3.8 μm, not more than 3.7 μm, not more than 3.6 μm, not more than 3.5 μm, not more than 3.4 μm, not more than 3.3 μm, not more than 3.2 μm, not more than 3.1 μm or not more than 3.0 μm.
A particularly preferred range for Dv50 of the aerosol is in the range 2-3 μm.
The air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that, when the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the average magnitude of velocity of air in the vaporisation chamber is in the range 0-1.3 ms−1. The average magnitude velocity of air may be calculated based on knowledge of the geometry of the vaporisation chamber and the flow rate.
When the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the average magnitude of velocity of air in the vaporisation chamber may be at least 0.001 ms−1, or at least 0.005 ms−1, or at least 0.01 ms−1, or at least 0.05 ms−1.
When the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the average magnitude of velocity of air in the vaporisation chamber may be at most 1.2 ms−1, at most 1.1 ms−1, at most 1.0 ms−1, at most 0.9 ms−1, at most 0.8 ms−1, at most 0.7 ms−1 or at most 0.6 ms−1.
The air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that, when the air flow rate inhaled by the user through the apparatus is 2.0 L min−1, the average magnitude of velocity of air in the vaporisation chamber is in the range 0-1.3 ms−1. The average magnitude velocity of air may be calculated based on knowledge of the geometry of the vaporisation chamber and the flow rate.
When the air flow rate inhaled by the user through the apparatus is 2.0 L min−1, the average magnitude of velocity of air in the vaporisation chamber may be at least 0.001 ms−1, or at least 0.005 ms−1, or at least 0.01 ms−1, or at least 0.05 ms−1.
When the air flow rate inhaled by the user through the apparatus is 2.0 L min−1, the average magnitude of velocity of air in the vaporisation chamber may be at most 1.2 ms−1, at most 1.1 ms−1, at most 1.0 ms−1, at most 0.9 ms−1, at most 0.8 ms−1, at most 0.7 ms−1 or at most 0.6 ms−1.
When the calculated average magnitude of velocity of air in the vaporisation chamber is in the ranges specified, it is considered that the resultant aerosol particle size is advantageously controlled to be in a desirable range. It is further considered that the configuration of the apparatus can be selected so that the average magnitude of velocity of air in the vaporisation chamber can be brought within the ranges specified, at the exemplary flow rate of 1.3 L min−1 and/or the exemplary flow rate of 2.0 L min−1.
The aerosol generator may comprise a heatable wick (vaporiser element) to be loaded with aerosol precursor, the vaporiser element being heatable by a heater and presenting a vaporiser element surface to air in the vaporisation chamber. A vaporiser element region may be defined as a volume extending outwardly from the vaporiser element surface to a distance of 1 mm from the vaporiser element surface. The air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that, when the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the average magnitude of velocity of air in the vaporiser element region is in the range 0-1.2 ms−1. The average magnitude of velocity of air in the vaporiser element region may be calculated using computational fluid dynamics.
When the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the average magnitude of velocity of air in the vaporiser element region may be at least 0.001 ms−1, or at least 0.005 ms−1, or at least 0.01 ms−1, or at least 0.05 ms−1.
When the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the average magnitude of velocity of air in the vaporiser element region may be at most 1.1 ms−1, at most 1.0 ms−1, at most 0.9 ms−1, at most 0.8 ms−1, at most 0.7 ms−1 or at most 0.6 ms−1.
The air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that, when the air flow rate inhaled by the user through the apparatus is 2.0 L min−1, the average magnitude of velocity of air in the vaporiser element region is in the range 0-1.2 ms−1. The average magnitude of velocity of air in the vaporiser element region may be calculated using computational fluid dynamics.
When the air flow rate inhaled by the user through the apparatus is 2.0 L min−1, the average magnitude of velocity of air in the vaporiser element region may be at least 0.001 ms−1, or at least 0.005 ms−1, or at least 0.01 ms−1, or at least 0.05 ms−1.
When the air flow rate inhaled by the user through the apparatus is 2.0 L min−1, the average magnitude of velocity of air in the vaporiser element region may be at most 1.1 ms−1, at most 1.0 ms−1, at most 0.9 ms−1, at most 0.8 ms−1, at most 0.7 ms−1 or at most 0.6 ms−1.
When the average magnitude of velocity of air in the vaporiser element region is in the ranges specified, it is considered that the resultant aerosol particle size is advantageously controlled to be in a desirable range. It is further considered that the velocity of air in the vaporiser element region is more relevant to the resultant particle size characteristics than consideration of the velocity in the vaporisation chamber as a whole. This is in view of the significant effect of the velocity of air in the vaporiser element region on the cooling of the vapour emitted from the vaporiser element surface.
Additionally or alternatively is it relevant to consider the maximum magnitude of velocity of air in the vaporiser element region.
The air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that, when the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the maximum magnitude of velocity of air in the vaporiser element region is in the range 0-2.0 ms−1.
When the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the maximum magnitude of velocity of air in the vaporiser element region may be at least 0.001 ms−1, or at least 0.005 ms−1, or at least 0.01 ms−1, or at least 0.05 ms−1.
When the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the maximum magnitude of velocity of air in the vaporiser element region may be at most 1.9 ms−1, at most 1.8 ms−1, at most 1.7 ms−1, at most 1.6 ms−1, at most 1.5 ms−1, at most 1.4 ms−1, at most 1.3 ms−1 or at most 1.2 ms−1.
The air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that, when the air flow rate inhaled by the user through the apparatus is 2.0 L min−1, the maximum magnitude of velocity of air in the vaporiser element region is in the range 0-2.0 ms−1.
When the air flow rate inhaled by the user through the apparatus is 2.0 L min−1, the maximum magnitude of velocity of air in the vaporiser element region may be at least 0.001 ms−1, or at least 0.005 ms−1, or at least 0.01 ms−1, or at least 0.05 ms−1.
When the air flow rate inhaled by the user through the apparatus is 2.0 L min−1, the maximum magnitude of velocity of air in the vaporiser element region may be at most 1.9 ms−1, at most 1.8 ms−1, at most 1.7 ms−1, at most 1.6 ms−1, at most 1.5 ms−1, at most 1.4 ms−1, at most 1.3 ms−1 or at most 1.2 ms−1.
It is considered that configuring the apparatus in a manner to permit such control of velocity of the airflow at the vaporiser permits the generation of aerosols with particularly advantageous particle size characteristics, including Dv50 values.
Additionally or alternatively is it relevant to consider the turbulence intensity in the vaporiser chamber in view of the effect of turbulence on the particle size of the generated aerosol. For example, the air inlet, flow passage, outlet and the vaporisation chamber may be configured so that, when the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the turbulence intensity in the vaporiser element region is not more than 1%.
When the air flow rate inhaled by the user through the apparatus is 1.3 L min−1, the turbulence intensity in the vaporiser element region may be not more than 0.95%, not more than 0.9%, not more than 0.85%, not more than 0.8%, not more than 0.75%, not more than 0.7%, not more than 0.65% or not more than 0.6%.
It is considered that configuring the apparatus in a manner to permit such control of the turbulence intensity in the vaporiser element region permits the generation of aerosols with particularly advantageous particle size characteristics, including Dv50 values.
Following detailed investigations, the inventors consider, without wishing to be bound by theory, that the particle size characteristics of the generated aerosol may be determined by the cooling rate experienced by the vapour after emission from the vaporiser element (wick). In particular, it appears that imposing a relatively slow cooling rate on the vapour has the effect of generating aerosols with a relatively large particle size. The parameters discussed above (velocity and turbulence intensity) are considered to be mechanisms for implementing a particular cooling dynamic to the vapour.
More generally, it is considered that the air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that a desired cooling rate is imposed on the vapour. The particular cooling rate to be used depends of course on the nature of the aerosol precursor and other conditions. However, for a particular aerosol precursor it is possible to define a set of testing conditions in order to define the cooling rate, and by extension this imposes limitations on the configuration of the apparatus to permit such cooling rates as are shown to result in advantageous aerosols. Accordingly, the air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that the cooling rate of the vapour is such that the time taken to cool to 50° C. is not less than 16 ms, when tested according to the following protocol. The aerosol precursor is an e-liquid consisting of 1.6% freebase nicotine and the remainder a 65:35 propylene glycol and vegetable glycerine mixture, the e-liquid having a boiling point of 209° C. Air is drawn into the air inlet at a temperature of 25° C. The vaporiser is operated to release a vapour of total particulate mass 5 mg over a 3 second duration from the vaporiser element surface in an air flow rate between the air inlet and outlet of 1.3 L min−1.
Additionally or alternatively, the air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that the cooling rate of the vapour is such that the time taken to cool to 50° C. is not less than 16 ms, when tested according to the following protocol. The aerosol precursor is an e-liquid consisting of 1.6% freebase nicotine and the remainder a 65:35 propylene glycol and vegetable glycerine mixture, the e-liquid having a boiling point of 209° C. Air is drawn into the air inlet at a temperature of 25° C. The vaporiser is operated to release a vapour of total particulate mass 5 mg over a 3 second duration from the vaporiser element surface in an air flow rate between the air inlet and outlet of 2.0 L min−1.
Cooling of the vapour such that the time taken to cool to 50° C. is not less than 16 ms corresponds to an equivalent linear cooling rate of not more than 10° C./ms.
The equivalent linear cooling rate of the vapour to 50° C. may be not more than 9° C./ms, not more than 8° C./ms, not more than 7° C./ms, not more than 6° C./ms or not more than 5° C./ms.
Cooling of the vapour such that the time taken to cool to 50° C. is not less than 32 ms corresponds to an equivalent linear cooling rate of not more than 5° C./ms.
The testing protocol set out above considers the cooling of the vapour (and subsequent aerosol) to a temperature of 50° C. This is a temperature which can be considered to be suitable for an aerosol to exit the apparatus for inhalation by a user without causing significant discomfort. It is also possible to consider cooling of the vapour (and subsequent aerosol) to a temperature of 75° C. Although this temperature is possibly too high for comfortable inhalation, it is considered that the particle size characteristics of the aerosol are substantially settled by the time the aerosol cools to this temperature (and they may be settled at still higher temperature).
Accordingly, the air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that the cooling rate of the vapour is such that the time taken to cool to 75° C. is not less than 4.5 ms, when tested according to the following protocol. The aerosol precursor is an e-liquid consisting of 1.6% freebase nicotine and the remainder a 65:35 propylene glycol and vegetable glycerine mixture, the e-liquid having a boiling point of 209° C. Air is drawn into the air inlet at a temperature of 25° C. The vaporiser is operated to release a vapour of total particulate mass 5 mg over a 3 second duration from the vaporiser element surface in an air flow rate between the air inlet and outlet of 1.3 L min−1.
Additionally or alternatively, the air inlet(s), flow passage(s) (bypass and/or main and/or outlet), outlet and the vaporisation chamber may be configured so that the cooling rate of the vapour is such that the time taken to cool to 75° C. is not less than 4.5 ms, when tested according to the following protocol. The aerosol precursor is an e-liquid consisting of 1.6% freebase nicotine and the remainder a 65:35 propylene glycol and vegetable glycerine mixture, the e-liquid having a boiling point of 209° C. Air is drawn into the air inlet at a temperature of 25° C. The vaporiser is operated to release a vapour of total particulate mass 5 mg over a 3 second duration from the vaporiser element surface in an air flow rate between the air inlet and outlet of 2.0 L min−1.
Cooling of the vapour such that the time taken to cool to 75° C. is not less than 4.5 ms corresponds to an equivalent linear cooling rate of not more than 30° C./ms.
The equivalent linear cooling rate of the vapour to 75° C. may be not more than 29° C./ms, not more than 28° C./ms, not more than 27° C./ms, not more than 26° C./ms, not more than 25° C./ms, not more than 24° C./ms, not more than 23° C./ms, not more than 22° C./ms, not more than 21° C./ms, not more than 20° C./ms, not more than 19° C./ms, not more than 18° C./ms, not more than 17° C./ms, not more than 16° C./ms, not more than 15° C./ms, not more than 14° C./ms, not more than 13° C./ms, not more than 12° C./ms, not more than 11° C./ms or not more than 10° C./ms.
Cooling of the vapour such that the time taken to cool to 75° C. is not less than 13 ms corresponds to an equivalent linear cooling rate of not more than 10° C./ms.
It is considered that configuring the apparatus in a manner to permit such control of the cooling rate of the vapour permits the generation of aerosols with particularly advantageous particle size characteristics, including Dv50 values.
The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.
So that the invention may be understood, and so that further aspects and features thereof may be appreciated, embodiments illustrating the principles of the invention will now be discussed in further detail with reference to the accompanying figures, in which:
Further background to the present invention and further aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. The contents of all documents mentioned in this text are incorporated herein by reference in their entirety.
As is apparent from
The system 110 is configured to vaporise an aerosol precursor, which in the illustrated reference arrangement is in the form of a nicotine-based e-liquid 160. The e-liquid 160 comprises nicotine and a base liquid including propylene glycol and/or vegetable glycerine. In the present arrangement, the e-liquid 160 is flavoured by a flavourant. In other embodiments, the e-liquid 160 may be flavourless and thus may not include any added flavourant.
In some embodiments, the e-liquid (i.e. aerosol precursor) may be the only part of the system that is truly “single-use”. That is, the tank may be refillable with e-liquid or the e-liquid may be stored in a non-consumable component of the system. For example, in such embodiments, the e-liquid may be stored in a tank located in the main body or stored in another component that is itself not single-use (e.g. a refillable cartomizer).
The external wall of tank 152 is provided by a casing of the consumable 150. The tank 152 annularly surrounds, and thus defines a portion of, a passage 170 that extends between a vaporiser inlet 172 and an outlet 174 at opposing ends of the consumable 150. In this respect, the passage 170 comprises an upstream end at the end of the consumable 150 that engages with the main body 120, and a downstream end at an opposing end of the consumable 150 that comprises a mouthpiece 154 of the system 110.
When the consumable 150 is received in the cavity of the main body 120 as shown in
When the consumable 150 is engaged with the main body 120, a user can inhale (i.e. take a puff) via the mouthpiece 154 so as to draw air through the passage 170, and so as to form an airflow (indicated by the dashed arrows in
The smoking substitute system 110 is configured to vaporise the e-liquid 160 for inhalation by a user. To provide this operability, the consumable 150 comprises a heater having a porous wick 162 and a resistive heating element in the form of a heating filament 164 that is helically wound (in the form of a coil) around a portion of the porous wick 162. The porous wick 162 extends across the passage 170 (i.e. transverse to a longitudinal axis of the passage 170 and thus also transverse to the air flow along the passage 170 during use) and opposing ends of the wick 162 extend into the tank 152 (so as to be immersed in the e-liquid 160). In this way, e-liquid 160 contained in the tank 152 is conveyed from the opposing ends of the porous wick 162 to a central portion of the porous wick 162 so as to be exposed to the airflow in the passage 170.
The helical filament 164 is wound about the exposed central portion of the porous wick 162 and is electrically connected to an electrical interface in the form of electrical contacts 156 mounted at the end of the consumable that is proximate the main body 120 (when the consumable and the main body are engaged). When the consumable 150 is engaged with the main body 120, electrical contacts 156 make contact with corresponding electrical contacts (not shown) of the main body 120. The main body electrical contacts are electrically connectable to a power source (not shown) of the main body 120, such that (in the engaged position) the filament 164 is electrically connectable to the power source. In this way, power can be supplied by the main body 120 to the filament 164 in order to heat the filament 164. This heats the porous wick 162 which causes e-liquid 160 conveyed by the porous wick 162 to vaporise and thus to be released from the porous wick 162. The vaporised e-liquid becomes entrained in the airflow and, as it cools in the airflow (between the heated wick and the outlet 174 of the passage 170), condenses to form an aerosol. This aerosol is then inhaled, via the mouthpiece 154, by a user of the system 110. As e-liquid is lost from the heated portion of the wick, further e-liquid is drawn along the wick from the tank to replace the e-liquid lost from the heated portion of the wick.
The filament 164 and the exposed central portion of the porous wick 162 are positioned across the passage 170. More specifically, the part of passage that contains the filament 164 and the exposed portion of the porous wick 162 forms a vaporisation chamber. In the illustrated example, the vaporisation chamber has the same cross-sectional diameter as the passage 170. However, in some embodiments the vaporisation chamber may have a different cross sectional profile compared with the passage 170.
For example, the vaporisation chamber may have a larger cross sectional diameter than at least some of the downstream part of the passage 170 so as to enable a longer residence time for the air inside the vaporisation chamber.
The part of the passage downstream from the vaporisation chamber can be considered as an outlet air flow passage.
When the user inhales, air is drawn from through the inlets 176 shown in
At substantially the same time as the airflow passes around the porous wick 162, the filament 164 is heated so as to vaporise the e-liquid which has been wicked into the porous wick. The airflow passing around the porous wick 162 picks up this vaporised e-liquid, and the vapour-containing airflow is drawn in direction 403 further down passage 170.
The power source of the main body 120 may be in the form of a battery (e.g. a rechargeable battery such as a lithium ion battery). The main body 120 may comprise a connector in the form of e.g. a USB port for recharging this battery. The main body 120 may also comprise a controller that controls the supply of power from the power source to the main body electrical contacts (and thus to the filament 164). That is, the controller may be configured to control a voltage applied across the main body electrical contacts, and thus the voltage applied across the filament 164. In this way, the filament 164 may only be heated under certain conditions (e.g. during a puff and/or only when the system is in an active state). In this respect, the main body 120 may include a puff sensor (not shown) that is configured to detect a puff (i.e. inhalation). The puff sensor may be operatively connected to the controller so as to be able to provide a signal, to the controller, which is indicative of a puff state (i.e. puffing or not puffing). The puff sensor may, for example, be in the form of a pressure sensor or an acoustic sensor.
Although not shown, the main body 120 and consumable 150 may comprise a further interface which may, for example, be in the form of an RFID reader, a barcode or QR code reader. This interface may be able to identify a characteristic (e.g. a type) of a consumable 150 engaged with the main body 120. In this respect, the consumable 150 may include any one or more of an RFID chip, a barcode or QR code, or memory within which is an identifier and which can be interrogated via the interface.
An apparatus according to an embodiment of the invention is configured such that in use, at least part of the air flow drawn by a user through the apparatus from the air inlet to the outlet bypasses the vaporisation chamber defined by the enclosure. A second reference arrangement of an apparatus, shown in
In
The provision of a bypass passage 180 means that a part of the air drawn through the smoking substitute apparatus 150a when a user inhales via the mouthpiece 154 is not drawn through the vaporisation chamber. This has the effect of reducing the flow rate through the vaporisation chamber in correspondence with the respective flow resistances presented by the vaporiser passage 170 and the bypass passage 180. This can reduce the correlation between the flow rate through the smoking substitute apparatus 150a (i.e. the user's draw rate) and the particle size generated when the e-liquid 160 is vaporised and subsequently forms an aerosol. Therefore, the smoking substitute apparatus 150a of the second reference arrangement (and of course of the present invention too) can deliver a more consistent aerosol to a user.
Furthermore, the smoking substitute apparatus 150a of the second reference arrangement is capable of producing an increased particle droplet size, d50, based on typical inhalation rates undertaken by a user, compared to the first reference arrangement of
The bypass passage and vaporiser passage extend from a common device inlet 176. This has the benefit of ensuring more consistent airflow through the bypass passage 180 and vaporiser passage 170 across the lifetime of the smoking substitute apparatus 150a, since any obstruction that impinges on an air inlet 176 will affect the airflow through both passages equally. The impact of inlet manufacturing variations can also be reduced for the same reason. This can therefore improve the user experience for the smoking substitute apparatus 150a. Furthermore, the provision of a common device inlet 176 simplifies the construction and external appearance of the device.
The bypass passage 180 and vaporiser passage 170 separate upstream of the vaporisation chamber. Therefore, no vapour is drawn through the bypass passage 180. Furthermore, because the bypass passage leads to outlet 184 that is separate from outlet 174 of the vaporiser passage, substantially no mixing of the bypass air and vaporiser air occurs within the smoking substitute apparatus 150a. Such mixing could otherwise lead to excessive cooling of the vapour and hence a build-up of condensation within the smoking substitute apparatus 150a. Such condensation could have adverse implications for delivering vapour to the user, for example by causing the user to draw liquid droplets rather than vapour when “puffing” on the mouthpiece 154.
A further example of a bypass air flow is presented by a third reference arrangement. Accordingly, in some embodiments, the apparatus may include one or a combination of features of a third reference arrangement (and variations thereof), shown schematically in
The consumable 250 comprises a housing. The consumable 250 comprises an aerosol generation chamber 280 in the housing. As shown in
In the illustrated third reference arrangement, the housing has a plurality of air inlets 272 defined or opened at the sidewall of the housing. An outlet 274 is defined or opened at a second end of the consumable 250 that comprises a mouthpiece 254. A pair of passages 270 each extend between the respective air inlets 272 and the outlet 274 to provide flow passage for an air flow 412 as a user puffs on the mouthpiece 254. The chamber outlet 282 is configured to be in fluid communication with the passages 270. The passages 270 extend from the air inlets 272 towards the first end of the consumable 250 before routing back to towards the outlet 274 at the second end of the consumable 250. That is, a portion of each of the passages 270 axially extends alongside the aerosol generation chamber 280. The path of the air flow path 412 is illustrated in
In some other variations of the third reference arrangement, the housing may not be provided with any air inlet for an air flow to enter the housing. For example, the chamber outlet may be directly connected to the outlet of the housing by an aerosol passage and therefore said aerosol passage may only convey aerosol as generated in the aerosol generation chamber. In these variations, the discharge of aerosol may be driven at least in part by the pressure increase during vaporisation of aerosol form.
Referring back to the third reference arrangement of
In the illustrated third reference arrangement, the chamber outlet 282 is configured to be in fluid communication with a junction 290 at each of the passages 270 through a respective vapour channel 292. The junctions 290 merge the vapour channels 292 with their respective passages 270 such that vapour and/or aerosol formed in the aerosol generation chamber 280 may expand or entrain into the passages 270 through junction inlets of said junctions 290. The vapour channels form a buffering volume to minimise the amount of air flow that may back flow into the aerosol generation chamber 280. In some other variations of the third reference arrangement (not illustrated), the chamber outlet 282 may directly open towards the junction 290 at the passage, and therefore in such variations the vapour channel 292 may be omitted.
In some variations of the third reference arrangement (not illustrated), the chamber outlet may be closed by a one way valve. Said one way valve may be configured to allow a one way flow passage for the vapour and/or aerosol to be discharged from the aerosol generation chamber, and to reduce or prevent the air flow in the passages from entering the aerosol generation chamber.
In the illustrated third reference arrangement, the aerosol generation chamber 280 is configured to have a length of 20 mm and a volume of 680 mm3. The aerosol generation chamber is configured to allow vapour to be expulsed through the chamber outlet at a rate greater than 0.1 mg/second. In other variations of the third reference arrangement the aerosol generation chamber may be configured to have an internal volume ranging between 68 mm3 to 680 mm3, wherein the length of the aerosol generation chamber may range between 2 mm to 20 mm.
As shown in
The aerosol generation chamber 280 comprises a heater extending across its width. The heater comprises a porous wick 262 and a heating filament 264 helically wound around a portion of the porous wick 162. A tank 252 is provided in the space between the aerosol generation chamber 280 and the outlet 274, the tank being for storing a reservoir of aerosol precursor. Therefore in contrast with the reference arrangement as shown in
The heating filament is electrically connected to electrical contacts 256 at the base of the aerosol generation chamber 280, sealed to prevent air ingress or fluid leakage. As shown in
The vaporised aerosol precursor, or aerosol in the condensed form, may discharge from the aerosol generation chamber 280 based on pressure difference between the aerosol generation chamber 280 and the passages 270. Such pressure difference may arise form i) an increased pressure in the aerosol generation chamber 280 during vaporisation of aerosol form, and/or ii) a reduced pressure in the passage during a puff.
For example, when the heater is energised and forms a vapour, it expands in to the stagnant cavity of the aerosol generation chamber 280 and thereby causes an increase in internal pressure therein. The vaporised aerosol precursor may immediately begin to cool and may form aerosol droplets. Such increase in internal pressure causes convection inside the aerosol generation chamber which aids expulsing aerosol through the chamber outlet 282 and into the passages 270.
In the illustrated third reference arrangement, the heater is positioned within the stagnant cavity of the aerosol generation chamber 280, e.g. the heater is spaced from the chamber outlet 282. Such arrangement may reduce or prevent the amount of air flow entering the aerosol generation chamber, and therefore it may minimise the amount of turbulence in the vicinity of the heater. Furthermore, such arrangement may increase the residence time of vapour in the stagnant aerosol generation chamber 280, and thereby may result in the formation of larger aerosol droplets. In some other variations of the third reference arrangement, the heater may be positioned adjacent to the chamber outlet and therefore that the path of vapour 414 from the heater to the chamber outlet 282 is shortened. This may allow vapour to be drawn into or entrained with the air flow in a more efficient manner.
The junction inlet at each of the junctions 290 opens in a direction orthogonal or non-parallel to the air flow. That is, the junction inlet each opens at a sidewall of the respective passages 270. This allows the vapour and/or aerosol from the aerosol generation chamber 280 to entrain into the air flow at an angle, and thus improving localised mixing of the different streams, as well as encouraging aerosol formation. The aerosol may be fully formed in the air flow and be drawn out through the outlet at the mouthpiece.
With the absence of, or much reduced, air flow in the aerosol generation chamber, the aerosol as generated by the illustrated third reference arrangement has a median droplet size d50 of at least 1 μm. More preferably, the aerosol as generated by the illustrated third reference arrangement has a median droplet size d50 of ranged between 2 μm to 3 μm.
In contrast to the previously described second and third reference arrangements, the present invention routes bypass/auxiliary airflow through the part of the apparatus which supports the porous wick; the holder. A first embodiment of the present invention is illustrated in
The consumable 350 comprises a housing. The consumable 350 comprises an aerosol generation chamber 380 in the housing. As shown in
The housing has a plurality of air inlets 372 defined or opened at the sidewall of the housing. An outlet 374 is defined or opened at a second end of the consumable 350 that comprises a mouthpiece 354.
The apparatus of the present invention includes a holder 390 through which bypass inlet air passages extend. See in
An air flow 412 runs between the air inlets 372 and the space 368 through connecting passages. From that space the air flow branches into the bypass air flow 413, through the bypass inlet air flow passages 370, and a main air flow through a main inlet air flow passage 410 which extends through the holder from the space 368 to the aerosol generation chamber 380.
In this way each of these air inlets 372 acts as both the “air inlet” of the present invention as well as the main air inlet; accordingly these two are a single inlet part. Two such single inlets are illustrated. The connecting passages running from the air inlets 372 to the upstream end of the holder, here the space 368, are shared and thus form effectively extensions of both the bypass air inlet passages and the main inlet air flow passage; accordingly these two are a single passage. Two such single passages are illustrated.
In embodiments where such a main inlet air flow passage is not provided, the aerosol generation chamber is ‘stagnant’ as described above for the third reference arrangement.
The chamber outlet 382 is configured to be in fluid communication with the passages 370 and 410. A portion of each of the passages 370 axially extends alongside the aerosol generation chamber 380 as it bypasses the chamber. The path of the air flow path 412 is illustrated in
As the air flow passes through the aerosol generation chamber 380 it picks up vapour to form a vapour/aerosol flow 411. After the aerosol generation chamber 380, the bypass air flow(s) 413 join with this vapour/aerosol flow to form a combined vapour and aerosol flow 414. This flows through an outlet air flow passage 440 to the outlet 374.
The chamber outlet 382 is positioned downstream from the heater/aerosol generator in the direction of the vapour and aerosol flow 414 and permits, in use, aerosol generated by the heater to be entrained into an air flow 411. In some other variations, the aerosol generation chamber 380 may comprise a plurality of chamber outlets 382. In contrast with the consumable 150 as shown in
In some variations (not illustrated), the chamber outlet may be closed by a one way valve. Said one way valve may be configured to allow a one way flow passage for the vapour and/or aerosol to be discharged from the aerosol generation chamber, and to reduce or prevent the air flow in the bypass or outlet air flow passages from entering the aerosol generation chamber.
The aerosol generation chamber 380 may be configured to have a length of 20 mm and a volume of 680 mm3. The aerosol generation chamber may be configured to allow vapour to be expulsed through the chamber outlet at a rate greater than 0.1 mg/second. In other variations the aerosol generation chamber may be configured to have an internal volume ranging between 68 mm3 to 680 mm3, wherein the length of the aerosol generation chamber may range between 2 mm to 20 mm.
The aerosol generation chamber 380 comprises a heater extending across its width, which is held by the holder 390. The heater comprises a porous wick 362 and a heating filament helically wound around a portion of the porous wick 362. A tank 352 is provided in the space between the housing and the core components, the tank being for storing a reservoir of aerosol precursor. The end portions of the porous wick 362 each extend through the sidewalls of the aerosol generation chamber 380 and into the tank 352. The wick 362, saturated with aerosol precursor, may prevent gas flow passage into the tank 252. Such an arrangement may allow the aerosol precursor stored in the tank 352 to convey towards the porous wick 362 by gravity.
The heating filament is electrically connected to electrical contacts 356 at the base of the aerosol generation chamber 380, sealed to prevent air ingress or fluid leakage. When the first end of the consumable 350 is received into the main body 120, the electrical contacts 356 establish electrical communication with corresponding electrical contacts of the main body 120, and thereby allow the heater to be energised.
The vaporised aerosol precursor, or aerosol in the condensed form, may discharge from the aerosol generation chamber 380 based partly or wholly on pressure difference between the aerosol generation chamber 380 and the bypass inlet air flow passages 370. Such pressure difference may arise form i) an increased pressure in the aerosol generation chamber 380 during vaporisation of aerosol form, and/or ii) a reduced pressure in the passage during a puff.
For example, when the heater is energised and forms a vapour, it expands into the aerosol generation chamber 380 and thereby causes an increase in internal pressure therein. The vaporised aerosol precursor may immediately begin to cool and may form aerosol droplets. Such increase in internal pressure causes convection inside the aerosol generation chamber which aids expulsing aerosol through the chamber outlet 382. Where, as illustrated, a main inlet air flow passage 410 is provided, an air flow drawn through that can assist.
As air is drawn through the apparatus by the user, for example by drawing on the outlet 374/mouthpiece 354, air flows through and along the paths illustrated. This may include passing a pressure sensor positioned, for example, in a passage between an air inlet 372 and the space 368 upstream of the holder 390. In
Accordingly, any reduction of air speed over the aerosol generator that might be caused by the presence of the bypass air flow 413 will not impact the device pressure senor from activating. This can assure a consistent and reliable activation of the heater and thus vapour/aerosol generation.
More detail of the holder 390 and the air flows through it is shown in
The upstream end (outer face surface) of the holder 390 is shown in more detail in
Electrical contacts 356 can be seen positioned also on the upstream end face of the holder 390.
The effect of this on air flow through the holder 390 can be seen in
There now follows a disclosure of certain experimental work undertaken to determine the effects of certain conditions in the smoking substitute apparatus on the particle size of the generated aerosol.
The experimental results reported here are relevant to the embodiments disclosed above in view of their demonstration of the control over particle size based on control of the conditions at the wick. In particular, the embodiments disclosed above have an effect on the air flow conditions and/or temperature in the vaporisation chamber, in view of the way in which bypass air flow is managed in the present invention.
Aerosol droplet size is a considered to be an important characteristic for smoking substitution devices. Droplets in the range of 2-5 μm are preferred in order to achieve improved nicotine delivery efficiency and to minimise the hazard of second-hand smoking. However, at the time of writing (September 2019), commercial EVP devices typically deliver aerosols with droplet size averaged around 0.5 μm, and to the knowledge of the inventors not a single commercially available device can deliver an aerosol with an average particle size exceeding 1 μm.
The present inventors speculate, without themselves wishing to be bound by theory, that there has to date been a lack of understanding in the mechanisms of e-liquid evaporation, nucleation and droplet growth in the context of aerosol generation in smoking substitute devices. The present inventors have therefore studied these issues in order to provide insight into mechanisms for the generation of aerosols with larger particles. The present inventors have carried out experimental and modelling work alongside theoretical investigations, leading to significant achievements as now reported.
This disclosure considers the roles of air velocity, air turbulence and vapour cooling rate in affecting aerosol particle size.
In this work, a Malvern PANalytical Spraytec laser diffraction system was employed for the particle size measurement. In order to limit the number of variables, the same coil and wick (1.5 ohms Ni—Cr coil, 1.8 mm Y07 cotton wick), the same e-liquid (1.6% freebase nicotine, 65:35 propylene glycol (PG)/vegetable glycerine (VG) ratio, no added flavour) and the same input power (10 W) were used in all experiments. Y07 represents the grade of cotton wick, meaning that the cotton has a linear density of 0.7 grams per meter.
Particle sizes were measured in accordance with ISO 13320: 2009 (E), which is an international standard on laser diffraction methods for particle size analysis. This is particularly well suited to aerosols, because there is an assumption in this standard that the particles are spherical (which is a good assumption for liquid-based aerosols). The standard is stated to be suitable for particle sizes in the range 0.1 micron to 3 mm.
The results presented here concentrate on the volume-based median particle size Dv50. This is to be taken to be the same as the parameter d50 used above.
The work reported here based on the inventors' insight that aerosol particle size might be related to: 1) air velocity; 2) flow rate; and 3) Reynolds number. In a given EVP device, these three parameters are inter-linked to each other, making it difficult to draw conclusions on the roles of each individual factor. In order to decouple these factors, experiments were carried out using a set of rectangular tubes having different dimensions. These were manufactured by 3D printing. The rectangular tubes were 3D printed in an MJP 2500 3D printer.
The rectangular tubes were manufactured to have same internal depth of 6 mm in order to accommodate the standardized coil and wick, however the tube internal width varied from 4.5 mm to 50 mm. In this disclosure, the “tube size” is referred to as the internal width of rectangular tubes.
The rectangular tubes with different dimensions were used to generate aerosols that were tested for particle size in a Malvern PANalytical Spraytec laser diffraction system. An external digital power supply was dialed to 2.6 A constant current to supply 10 W power to the heater coil in all experiments. Between two runs, the wick was saturated manually by applying one drop of e-liquid on each side of the wick.
Three groups of experiments were carried out in this study:
Table 1 shows a list of experiments in this study. The values in “calculated air velocity” column were obtained by simply dividing the flow rate by the intersection area at the centre plane of wick. Reynolds numbers (Re) were calculated through the following equation:
where: ρ is the density of air (1.225 kg/m3); v is the calculated air velocity in table 1; μ is the viscosity of air (1.48×10−5 m2/s); L is the characteristic length calculated by:
where: P is the perimeter of the flow path's intersection, and A is the area of the flow path's intersection.
Five repetition runs were carried out for each tube size and flow rate combination. Between adjacent runs there were at least 5 minutes wait time for the Spraytec system to be purged. In each run, real time particle size distributions were measured in the Spraytec laser diffraction system at a sampling rate of 2500 per second, the volume distribution median (Dv50) was averaged over a puff duration of 4 seconds. Measurement results were averaged and the standard deviations were calculated to indicate errors as shown in section 4 below.
The Reynolds numbers in Table 1 are all well below 1000, therefore, it is considered fair to assume all the experiments in section 2.1 would be under conditions of laminar flow. Further experiments were carried out and reported in this section to investigate the role of turbulence.
Turbulence intensity was introduced as a quantitative parameter to assess the level of turbulence. The definition and simulation of turbulence intensity is discussed below (see section 3.2).
Different device designs were considered in order to introduce turbulence. In the experiments reported here, jetting panels were added in the existing 12 mm rectangular tubes upstream of the wick. This approach enables direct comparison between different devices as they all have highly similar geometry, with turbulence intensity being the only variable.
For each of
These four devices were operated to generate aerosols following the procedure explained above (section 2.1) using a flow rate of 1.3 lpm and the generated aerosols were tested for particle size in the Spraytec laser diffraction system.
This experiment aimed to investigate the influence of inflow air temperature on aerosol particle size, in order to investigate the effect of vapour cooling rate on aerosol generation.
The experimental set up is shown in
Three smoking substitute apparatuses (referred to as “pods”) were tested in the study: pod 1 is the commercially available “myblu optimised” pod (
Pod 1, shown in longitudinal cross sectional view (in the width plane) in
Pod 2, shown in longitudinal cross sectional view (in the width plane) in
Mouthpiece 154z is formed at the upper part of the pod. Electrical contacts 156z are formed at the lower end of the pod. Wick 162z is held in a vaporisation chamber. The air flow direction is shown using arrows. Pod 3 uses a stagnant vaporiser chamber, with the air inlets bypassing the wick and picking up the vapour/aerosol downstream of the wick.
All three pods were filled with the same e-liquid (1.6% freebase nicotine, 65:35 PG/VG ratio, no added flavour). Three experiments were carried out for each pod: 1) standard measurement in ambient temperature; 2) only the inlet air was heated to 50° C.; and 3) both the inlet air and the pods were heated to 50° C. Five repetition runs were carried out for each experiment and the Dv50 results were taken and averaged.
In this study, modelling work was performed using COMSOL Multiphysics 5.4, engaged physics include: 1) laminar single-phase flow; 2) turbulent single-phase flow; 3) laminar two-phase flow; 4) heat transfer in fluids; and (5) particle tracing. Data analysis and data visualisation were mostly completed in MATLAB R2019a.
Air velocity in the vicinity of the wick is believed to play an important role in affecting particle size. In section 2.1, the air velocity was calculated by dividing the flow rate by the intersection area, which is referred to as “calculated velocity” in this work. This involves a very crude simplification that assumes velocity distribution to be homogeneous across the intersection area.
In order to increase reliability of the work, computational fluid dynamics (CFD) modelling was performed to obtain more accurate velocity values:
The CFD model uses a laminar single-phase flow setup. For each experiment, the outlet was configured to a corresponding flowrate, the inlet was configured to be pressure-controlled, the wall conditions were set as “no slip”. A 1 mm wide ring-shaped domain (wick vicinity) was created around the wick surface, and domain probes were implemented to assess the average and maximum magnitudes of velocity in this ring-shaped wick vicinity domain.
The CFD model outputs the average velocity and maximum velocity in the vicinity of the wick for each set of experiments carried out in section 2.1. The outcomes are reported in Table 2.
Turbulence intensity (I) is a quantitative value that represents the level of turbulence in a fluid flow system. It is defined as the ratio between the root-mean-square of velocity fluctuations, u′, and the Reynolds-averaged mean flow velocity,
where ux, uy and uz are the x-, y- and z-components of the velocity vector,
Higher turbulence intensity values represent higher levels of turbulence. As a rule of thumb, turbulence intensity below 1% represents a low-turbulence case, turbulence intensity between 1% and 5% represents a medium-turbulence case, and turbulence intensity above 5% represents a high-turbulence case.
In this study, turbulence intensity was obtained from CFD simulation using turbulent single-phase setup in COMSOL Multiphysics. For each of the four experiments explained in section 2.2, the outlet was set to 1.3 lpm, the inlet was set to be pressure-controlled, and all wall conditions were set to be “no slip”.
Turbulence intensity was assessed within the volume up to 1 mm away from the wick surface (defined as the wick vicinity domain). For the four experiments explained in section 2.2, the turbulence intensities are 0.55%, 0.77%, 1.06% and 1.34%, respectively, as also shown in
The cooling rate modelling involves three coupling models in COMSOL Multiphysics: 1) laminar two-phase flow; 2) heat transfer in fluids, and 3) particle tracing. The model is setup in three steps:
Laminar mixture flow physics was selected in this study. The outlet was configured in the same way as in section 3.1. However, this model includes two fluid phases released from two separate inlets: the first one is the vapour released from wick surface, at an initial velocity of 2.84 cm/s (calculated based on 5 mg total particulate mass over 3 seconds puff duration) with initial velocity direction normal to the wick surface; the second inlet is air influx from the base of tube, the rate of which is pressure-controlled.
2) Set Up Two-Way Coupling with Heat Transfer Physics
The inflow and outflow settings in heat transfer physics was configured in the same way as in the two-phase flow model. The air inflow was set to 25° C., and the vapour inflow was set to 209° C. (boiling temperature of the e-liquid formulation). In the end, the heat transfer physics is configured to be two-way coupled with the laminar mixture flow physics. The above model reaches steady state after approximately 0.2 second with a step size of 0.001 second.
A wave of 2000 particles were release from wick surface at t=0.3 second after the two-phase flow and heat transfer model has stabilised. The particle tracing physics has one-way coupling with the previous model, which means the fluid flow exerts dragging force on the particles, whereas the particles do not exert counterforce on the fluid flow. Therefore, the particles function as moving probes to output vapour temperature at each timestep.
The model outputs average vapour temperature at each time steps. A MATLAB script was then created to find the time step when the vapour cools to a target temperature (50° C. or 75° C.), based on which the vapour cooling rates were obtained (Table 3).
Particle size measurement results for the rectangular tube testing are shown in Table 4. For every tube size and flow rate combination, five repetition runs were carried out in the Spraytec laser diffraction system. The Dv50 values from five repetition runs were averaged, and the standard deviations were calculated to indicate errors, as shown in Table 4.
In this section, the roles of different factors affecting aerosol particle size will be discussed based on experimental and modelling results.
The particle size (Dv50) experimental results are plotted against calculated air velocity in
Different size tubes were tested at two flow rates: 1.3 lpm and 2.0 lpm. Both groups of data show the same trend that slower air velocity leads to larger particle size. The conclusion was made more convincing by the fact that these two groups of data overlap well in
In addition,
The above results lead to a strong conclusion that air velocity is an important factor affecting the particle size of EVP devices. Relatively large particles are generated when the air travels with slower velocity around the wick. It can also be concluded that flow rate, tube size and Reynolds number are not necessarily independently relevant to particle size, providing the air velocity is controlled in the vicinity of the wick.
In
The particle size measurement data were plotted against the average velocity (
The data in these two graphs indicates that in order to obtain an aerosol with Dv50 larger than 1 μm, the average velocity should be less than or equal to 1.2 m/s in the vicinity of the wick and the maximum velocity should be less than or equal to 2.0 m/s in the vicinity of the wick.
Furthermore, in order to obtain an aerosol with Dv50 of 2 μm or larger, the average velocity should be less than or equal to 0.6 m/s in the vicinity of the wick and the maximum velocity should be less than or equal to 1.2 m/s in the vicinity of the wick.
It is considered that typical commercial EVP devices deliver aerosols with Dv50 around 0.5 μm, and there is no commercially available device that can deliver aerosol with Dv50 exceeding 1 μm. It is considered that typical commercial EVP devices have average velocity of 1.5-2.0 m/s in the vicinity of the wick.
The role of turbulence has been investigated in terms of turbulence intensity, which is a quantitative characteristic that indicates the level of turbulence. In this work, four tubes of different turbulence intensities were used to general aerosols which were measured in the Spraytec laser diffraction system. The particle size (Dv50) experimental results are plotted against turbulence intensity in
The graph suggests a correlation between particle size and turbulence intensity, that lower turbulence intensity is beneficial for obtaining larger particle size. It is noted that when turbulence intensity is above 1% (medium-turbulence case), there are relatively large measurement fluctuations. In
The results clearly indicate that laminar air flow is favourable for the generation of aerosols with larger particles, and that the generation of large particle sizes is jeopardised by introducing turbulence. In
Without wishing to be bound by theory, the results are in line with the inventors' insight that control over the vapour cooling rate provides an important degree of control over the particle size of the aerosol. As reported above, the use of a slow air velocity can have the result of the formation of an aerosol with large Dv50. It is considered that this is due to slower air velocity allowing a slower cooling rate of the vapour.
Another conclusion related to laminar flow can also be explained by a cooling rate theory: laminar flow allows slow and gradual mixing between cold air and hot vapour, which means the vapour can cool down in slower rate when the airflow is laminar, resulting in larger particle size.
The results in
In section 3.3, the vapour cooling rates for each tube size and flow rate combination were obtained via multiphysics simulation. In
The data in these graphs indicates that in order to obtain an aerosol with Dv50 larger than 1 μm, the apparatus should be operable to require more than 16 ms for the vapour to cool to 50° C., or an equivalent (simplified to an assumed linear) cooling rate being slower than 10° C./ms. From an alternative viewpoint, in order to obtain an aerosol with Dv50 larger than 1 μm, the apparatus should be operable to require more than 4.5 ms for the vapour to cool to 75° C., or an equivalent (simplified to an assumed linear) cooling rate slower than 30° C./ms.
Furthermore, in order to obtain an aerosol with Dv50 of 2 μm or larger, the apparatus should be operable to require more than 32 ms for the vapour to cool to 50° C., or an equivalent (simplified to an assumed linear) cooling rate being slower than 5° C./ms. From an alternative viewpoint, in order to obtain an aerosol with Dv50 of 2 μm or larger, the apparatus should be operable to require more than 13 ms for the vapour to cool to 75° C., or an equivalent (simplified to an assumed linear) cooling rate slower than 10 C/ms.
In this work, particle size (Dv50) of aerosols generated in a set of rectangular tubes was studied in order to decouple different factors (flow rate, air velocity, Reynolds number, tube size) affecting aerosol particle size. It is considered that air velocity is an important factor affecting particle size-slower air velocity leads to larger particle size. When air velocity was kept constant, the other factors (flow rate, Reynolds number, tube size) has low influence on particle size.
The role of turbulence was also investigated. It is considered that laminar air flow favours generation of large particles, and introducing turbulence deteriorates (reduces) the particle size.
Modelling methods were used to simulate the average air velocity, the maximum air velocity, and the turbulence intensity in the vicinity of the wick. A COMSOL model with three coupled physics has also been developed to obtain the vapour cooling rate.
All experimental and modelling results support a cooling rate theory that slower vapour cooling rate is a significant factor in ensuring larger particle size. Slower air velocity, laminar air flow and higher inlet air temperature lead to larger particle size, because they all allow vapour to cool down at slower rates.
The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.
While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.
For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.
Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.
Throughout this specification, including the claims which follow, unless the context requires otherwise, the words “have”, “comprise”, and “include”, and variations such as “having”, “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.
It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means, for example, +/−10%.
The words “preferred” and “preferably” are used herein refer to embodiments of the invention that may provide certain benefits under some circumstances. It is to be appreciated, however, that other embodiments may also be preferred under the same or different circumstances. The recitation of one or more preferred embodiments therefore does not mean or imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure, or from the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21199572.5 | Sep 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/075194 | 9/9/2022 | WO |
