Patent Description:
Generating an aerosol using an aerosol-generating device is widely known in the art. It is known for example to generate an aerosol with a capillary aerosol-generating device. A capillary aerosol-generating device typically comprises a housing. The housing may comprise a capillary tube, surrounded by heating elements and an aerosol-forming chamber. The capillary tube may be connected to a reservoir holding vaporizable liquid.

Liquid flows through the capillary tube, which is heated until a supersaturated vapor is generated. The supersaturated vapor exits the capillary tube at the outlet of the capillary tube. The supersaturated vapor is mixed with air after it exits the capillary tube. Thereby the supersaturated vapor cools and condenses to produce an aerosol. The outlet of the aerosol-chamber of the capillary aerosol-generating device may be connected to a conveying aerosol tube.

Aerosol generation may pose a challenge during its use, especially for scientific studies, due to insufficiently controlled interaction of supersaturated vapor with air. In particular in capillary aerosol-generating devices this may result in aerosol droplets forming on the internal surface inside the capillary tube or an undesired particle size distribution. Such aerosol droplets can adhere to the internal surface of the capillary tube to function as the center of nucleation, such that the droplets eventually grow in sufficient size that they interfere with the airflow path.

Such unwanted effects not only reduce the net aerosol production but may also affect the results of a scientific study from the production of unwanted and unintended chemical decomposition products.

<CIT> relates to electronic vapour inhalers and to a cartridge having a flavour-release medium for use with an electronic vapour inhaler. The cartridge comprises an induction heatable element arranged in close proximity to the flavour-release medium.

<CIT> discloses a heated smoking system, which utilizes a heater positioned relative to an airflow system. The heated smoking system comprises a first flow route defined by a first channel, which directs air from outside the system to impinge against one or more electrical heating elements where the ambient air is mixed with vaporized substrate to form an aerosol. The aerosol is then conveyed to a downstream outlet end.

<CIT> is directed to an aerosol-generating device for heating an aerosol-forming substrate. The aerosol-generating device comprises a housing having a first air inlet, a second air inlet and an air outlet, wherein the second air inlet is larger than the first air inlet. The provision of the second air inlet between the heater and the air outlet allows a vaporized substrate to be rapidly cooled before it leaves the device through the air outlet.

Therefore, it would be desirable to provide an aerosol-generating device that allows increased control of the aerosol-generating process.

It would be particularly desirable to provide an aerosol-generating device that may be reliably used in scientific studies regarding aerosol generation. For this purpose it would be further desirable to have an aerosol-generating device that offers increased opportunities to control essential parameters of the liquid droplet aerosol formation process.

It would be particularly desirable to provide a capillary aerosol-generating device fulfilling the above objectives.

It would also be desirable to provide a capillary aerosol-generating device that has a housing that does not get too hot during use, such that handling of the device is improved.

In an embodiment of the invention there is provided an aerosol-generating device comprising a vaporization element having an outlet and being configured to vaporize a liquid. The aerosol-generating device further comprises an airflow passage extending from the outlet of the vaporization element and being configured to convey vapor to an outlet of the aerosol-generating device. The aerosol-generating device further comprises a hot air channel that is configured to direct heated air towards the outlet of the vaporization element. The aerosol-generating device also comprises a dilution air channel configured to direct ambient air into the aerosol-generating device and to mix the ambient air with the vapor conveyed in the airflow passage to form an aerosol.

In an embodiment of the invention the outlet of the hot air channel may be concentrically arranged around the outlet of the vaporization element.

The vaporization element may comprise a heater element. The heater element may be an electric heater element. The heater element may be a resistive heater or an inductive heater. The heater element may be a mesh heater or coil heater.

The vaporization element may comprise a wick and coil arrangement. The vaporization element may comprise a mesh heater arrangement.

The air flow passage may convey vapor and aerosol. The expression "vapor" is usually used to refer to a vaporized liquid. The expression "aerosol" is usually used to refer to a gaseous mixture in which a part of the vaporized liquid has condensed and forms liquid droplets suspended in the air flow.

The hot air from the hot air channel may form a "curtain" between the vapor and the aerosol conveyed in the airflow passage and surrounding elements of the aerosol-generating device. In this way the vapor is prevented from contacting colder parts of the aerosol-generating device. Thereby aerosol-formation may be better controlled, since most of the condensation that leads to the formation of aerosol is prevented by the hot air curtain. In addition, premature condensation of the vapor may be largely prevented.

In an embodiment of the invention the aerosol-generating device comprises a vaporization element with a capillary tube. Such aerosol-generating device is also referred to herein as "capillary aerosol-generating device".

In an embodiment of the invention there is provided a capillary aerosol-generating device comprising a capillary tube having an inlet and an outlet and being configured to convey vaporizable liquid. A heater element is provided in thermal contact with the capillary tube. The capillary aerosol-generating device further comprises a hot air channel that is configured to direct heated air towards the outlet of the capillary tube and to form an aerosol. The capillary aerosol-generating device also comprises a dilution air channel that is configured to direct ambient air into the device and to mix the ambient air with the aerosol.

By directing hot air towards the outlet of the capillary tube the vaporized liquid emerging from the outlet of the capillary tube is prevented from cooling down too quickly. In this way premature aerosol droplet formation in the vicinity of the outlet of the capillary tube or even within the capillary tube is efficiently reduced. Aerosol formation is supported by mixing the aerosol further downstream with ambient air. By adjusting the amount and the temperature of the different air streams, aerosol formation can be influenced to obtain for example a desired particle size distribution.

Moreover, the droplets are prevented from coming into contact with the heating elements. Thus, the risk that carbonyls or other unwanted constituents may be produced is reduced.

Due to the well-controlled aerosol formation, the aerosol-generating device may be advantageously used in scientific studies. Scientific studies may require test equipment which can operate reliably and reproducibly for an extended period of time. Such scientific studies may aim at mimicking a user's aerosol-consumption or may be directed as investigating long-time effects of aerosol consumption.

The outlet of the hot air channel may be arranged such that the hot air stream is routed around the outlet of the capillary tube of a capillary aerosol-generating device. The outlet of the hot air channel may be arranged around the outlet of the capillary tube. Preferably, the outlet of the hot air channel may be concentrically arranged around the outlet of the capillary tube. By routing the hot air stream around the outlet of the capillary tube, the hot air stream may form a cushion that shields the vaporized liquid from contacting any colder parts of the device and thereby prevents the vaporized liquid from condensing at such cooler surfaces.

The aerosol-generating device may comprise a heater module and an aerosol-forming module.

The heater module may comprise a housing, a heater element and a capillary tube in thermal contact with the heater element. The capillary tube may be arranged centrally in the capillary aerosol-generating device. The capillary tube may be configured to receive at its inlet a vaporizable liquid from a liquid reservoir. The capillary tube may be further configured such that the outlet of the capillary tube is in fluid connection with the aerosol-forming module.

The heater module may have a length of between <NUM> and <NUM> millimeters. The aerosol-forming module may have a diameter of <NUM> to <NUM> millimeters. Preferably, the heater module may have a length of about <NUM> millimeters and a diameter of <NUM> millimeters.

The aerosol-forming module may have any suitable construction. The aerosol-forming module may have a generally tubular form. The aerosol-forming module may comprise a housing in which an aerosol-forming chamber and a dilution chamber are defined. The aerosol-forming chamber may be arranged adjacent the upstream end of the aerosol-forming module and the dilution chamber may be arranged downstream from the aerosol-forming chamber. The aerosol-forming module may have an outlet end at which the aerosol may exit the aerosol-generating device.

The aerosol-forming module may have a length of between <NUM> to <NUM> millimeters. In capillary aerosol-generating devices the aerosol-forming module may have a larger length. In capillary aerosol-generating devices the aerosol-forming module may have a length of between <NUM> and <NUM> millimeters. The aerosol-forming module may have a diameter of <NUM> to <NUM> millimeters. The aerosol-forming module may preferably have a length of about <NUM> millimeters and a diameter of about <NUM> millimeters.

The heater module and the aerosol-forming module may be formed integrally.

The heater module and the aerosol-forming module may be formed from any suitable material. The heater module and the aerosol-forming module may be formed from glass or polymeric material such as pyrex or plexiglass.

The heater module and the aerosol-forming module may be releasably connected to each other. The releasable connection may be facilitated by any suitable connection means. The releasable connection may be facilitated by a connection element in the form of a front cap. The front cap may be configured of a generally tubular shape. One end of the front cap may be configured to be connected to the heater module. The other end of the front cap may be configured to be connected to the aerosol forming module. The front cap may comprise an opening to facilitate the fluid connection between the heater module and the aerosol-forming module.

The modular construction may have a plurality of beneficial effects. Modules may be changed depending on user preferences. In case of malfunction it is sufficient to replace defective modules, while operable modules may be continued to be used.

The connection element may be formed from polymeric material. The connection element may be formed from polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetheretherketoneketone (PEEKK) or polytetrafluoroethylene (PTFE).

The connection element may have a length of between <NUM> and <NUM> millimeters. The connection element may have a diameter of <NUM> to <NUM> millimeters. Preferably the connection element may have a length of about <NUM> millimeters and a diameter of about <NUM> millimeters.

The aerosol-generating device may further be configured such that the heated air from the hot air channel is introduced into the aerosol-forming chamber and the ambient air from the dilution air channel is introduced into the dilution chamber.

The capillary tube may be provided centrally in the heater module. The heater element may be arranged in thermal contact around the capillary tube. In this way good thermal contact between the heater element and the capillary tube is ensured. The housing may be arranged around the heater element.

The capillary tube may be made from any suitable inert material. Suitable materials for the capillary tube include glass and titanium.

The capillary tube may have a length of <NUM> to <NUM> millimeters and a diameter of up to <NUM> millimeters. Preferably, the capillary tube may have a length of about <NUM> millimeters and a diameter of <NUM> millimeter.

The heater element may be an electric heater element. The heater element may be a resistive or an inductive heater element. The heater element may comprise two half-cylindric heater segments. Each of the half-cylindric segments may comprise two heater segments such that in total the heater element may consist of four heater segments.

The heater element may be controlled by any suitable controller. A thermo-element may be provided for monitoring and controlling the temperature of the heater element.

A pump may be used to deliver the vaporizable liquid to the capillary tube. The pump may be a peristaltic pump.

The hot air channel may be arranged in the heater module. The hot air channel may be arranged in thermal contact with the heater element. The heater element may be used to provide the required heat to generate the hot air. In this way the heater element is used for two purposes at the same time. The heater element is used for providing the necessary heat to vaporize the liquid within the capillary tube. At the same time the heater element may be used to provide the required heat to generate the hot air stream. Such embodiment represents a particularly efficient use of the components of the device. The heater is used for the purpose of heating the liquid and the air to be mixed with the volatilized liquid. An additional heater is not required.

The hot air channel may be arranged radially outward from the heater element. The hot air channel may be arranged radially outward from the heater element and between the heater element and the housing of the heater module. The hot air channel may be provided as an annular channel arranged concentrically around the heater element. The hot air channel may be arranged such as to fully enclose the radial outer surface of the heater element. By arranging the hot air channel in this way, a large contact surface to the heater element is obtained. Such arrangement allows for good thermal contact and fast heat transfer to the hot air stream.

At the same time the hot air channel may act as a heat shield for the housing. In use, the heat generated by the heater element unavoidably travels towards the housing. Thus, the housing tends to get hot during use, which may be uncomfortable for handling of the device. By guiding the hot air stream between the heater element and the housing, the heat is taken up by the hot air stream, preventing the housing from becoming too hot during use.

In embodiments in which the hot air channel is arranged in the heater module, the heater module may comprise an air inlet. In addition, a further opening may be required to guide the hot air stream from the heater module into the aerosol-forming chamber of the aerosol-forming module. For this purpose, the connection element may be configured to establish a fluid connection of the hot air channel to the aerosol-forming chamber.

The connection element may comprise a pinhole inlet via which the hot air channel is fluidly connected to the aerosol-forming chamber. The pinhole inlet of the connection element may be concentrically arranged around the outlet of the capillary tube. The pinhole inlet of the connection element may have a diameter of up to <NUM> millimeters, and preferably a diameter of about <NUM> millimeters.

By providing the pinhole inlet concentrically around the outlet of the capillary tube the hot air stream emerges simultaneously with the vapor from the capillary tube into the aerosol-forming chamber of the aerosol-forming module. The hot air stream forms an envelope around the vapor and thereby prevents the vapor from cooling too quickly and condensing or clogging around the opening of the capillary tube.

The hot air channel may also be arranged in the aerosol-forming module, only. In such embodiments, the heated air is generated by another heater element, for example by an external heater. The aerosol-forming module comprises a first air inlet for introducing the externally heated air. The hot air stream is then guided within the aerosol-forming module towards the exit of the capillary tube. For this purpose the aerosol-forming module may comprise a first tubular element. The inner volume of the first tubular element may define the aerosol-forming chamber. The first tubular element may be arranged centrally within the aerosol-forming chamber. An annular space between the first tubular element and the housing of the aerosol-forming module may define the hot air channel that guides the hot air from the first air inlet towards the exit of the capillary tube. The outlet of the hot air channel may be formed such that the hot air stream again forms an envelope for the vapor leaving the capillary tube.

The hot air may be heated up to between <NUM> and <NUM> degrees Celsius. The hot air may be heated up to between <NUM> and <NUM> degrees Celsius.

The dilution air channel may be arranged in the aerosol-forming module of the aerosol-generating device. The dilution air channel is configured to direct cold, ambient air into the device and to mix the ambient air with the aerosol. The cold air stream may be directed into the dilution chamber. The cold air stream may be mixed in the dilution chamber with the aerosol generated in the upstream aerosol-forming chamber. By mixing the aerosol with the ambient air the aerosol enhances its volume. The resulting diluted aerosol flows onwards to an air outlet of the aerosol-generating device with no or substantially reduced condensation of aerosol on the internal surfaces of the aerosol-forming module.

The ambient air may be cold air. The ambient air may be conditioned before mixing with the aerosol. Conditioning the ambient air may include adjusting relative humidity, temperature and filtering. The ambient air may be conditioned to any temperature between - <NUM> and <NUM> degrees Celsius. The ambient air may be process air with a temperature of about <NUM> degrees Celsius. The ambient air may be heap-filtered process air with a temperature of about <NUM> degrees Celsius and a relative humidity of about <NUM> percent.

The aerosol-forming module may comprise a cold air inlet. The dilution air channel may extend from the cold air inlet to the dilution chamber. The dilution air channel may be formed in an annular space between a second tubular element and the housing of the aerosol-forming module. The second tubular element may be formed integrally with and in extension of the first tubular element.

The first and second tubular elements may have a combined total length of <NUM> to <NUM> milimeters and may preferably have a length of about <NUM> milimeters.

Air supplies for the air inlets of the aerosol-generating device may be provided as volume controlled air flow supplies. Air supplies may comprise pressurized (synthetic) air. The air supplies may be configured to provide, humidity adjusted, temperature conditioned and (hepa-) filtered process air. By using volume and pressure controlled process air a potential air backflow is avoided.

<FIG> depicts a first embodiment of a capillary aerosol-generating device <NUM> according to the present invention. The capillary aerosol-generating device <NUM> comprises a heater module <NUM> and an aerosol-forming module <NUM>, which are connected to each other using a connection element in the form of a front cap <NUM>.

The heater module <NUM> comprises a generally cylindric housing <NUM>, a heater element <NUM> and a capillary tube <NUM>. The capillary tube <NUM> is provided centrally in the heater module <NUM> and is surrounded by and in thermal contact with the heater element <NUM>. The heater element <NUM> comprises two half-cylindric heater segments 22a, 22b, which each comprise two further heater segments.

The capillary tube <NUM> is in fluid communication with a liquid reservoir (not shown). In <FIG> the capillary tube <NUM> receives the aerosolizable liquid from the liquid reservoir via a tubing <NUM>. A peristaltic pump (not shown) may be used to pump the liquid into the capillary tube <NUM>. The aerosolizable liquid is pumped through the capillary tube <NUM> and is heated by the thermal energy provided from the heater element <NUM>. Upon heating the aerosolizable liquid is formed into supersaturated vapor or hot aerosol.

The heater module <NUM> may also comprise one or more thermocouples (not shown) in order to monitor the temperature generated by the heater element <NUM>. The measured temperature may be used as feedback to control the energy provided to the heater element <NUM>.

The heater module <NUM> is connected to the aerosol-forming module <NUM> by front cap <NUM>. The front cap <NUM> is a generally tubular element that has a threading <NUM>, <NUM> on either end. The threading <NUM> at the upstream end is used to connect the front cap <NUM> to the heater module <NUM>. The threading <NUM> at the downstream end is used to connect the front cap <NUM> to the aerosol-forming module <NUM>. The front cap <NUM> has a central opening <NUM> through which the capillary tube <NUM> extends. When the capillary aerosol-generating device <NUM> is fully assembled the outlet <NUM> of the capillary tube <NUM> is located such that the vaporized liquid is discharged into an aerosol-forming chamber <NUM> of the aerosol-forming module <NUM>.

The aerosol-forming module <NUM> of the capillary aerosol-generating device <NUM> comprises a housing <NUM> with air inlets <NUM>, <NUM>, a first tubular element 48a and a second tubular element 48b. In the embodiment of <FIG> the first and second tubular elements 48a, 48b are integrally formed.

The aerosol-forming module <NUM> comprises a first air inlet <NUM> for introducing hot air. The hot air is created by using an external heater (not shown). The hot air stream is guided via an annular hot air channel <NUM> from the hot air inlet <NUM> of the aerosol-forming module <NUM> towards the exit <NUM> of the capillary tube <NUM>. The hot air channel <NUM> is formed in the annular space between the first tubular element 48a and the housing <NUM> of the aerosol-forming module <NUM>. The outlet of the hot air channel <NUM> is concentrically arranged around the outlet <NUM> of the capillary tube <NUM>. In this way the hot air stream discharged from the hot air channel <NUM> forms an envelope for the supersaturated vapor leaving the capillary tube <NUM>.

The inner volume of the first tubular element 48a defines the aerosol-forming chamber <NUM> into which the supersaturated vapor and the hot air stream is discharged.

The aerosol-forming module <NUM> comprises a second air inlet <NUM> for introducing cold ambient air. The cold air stream is guided via a dilution air channel <NUM> from the cold air inlet <NUM> of the aerosol-forming module towards the dilution chamber <NUM>. The dilution air channel <NUM> is formed in the annular space between the second tubular element 48b and the housing <NUM> of the aerosol-forming module <NUM>. In a dilution chamber <NUM> the cold air stream is mixed with the aerosol formed in the aerosol-forming chamber <NUM>. The resulting diluted aerosol flows onwards to an aerosol outlet <NUM> of the capillary aerosol-generating device <NUM>.

<FIG> shows a further embodiment of a capillary aerosol-generating device <NUM> according to the present invention. The capillary aerosol-generating device <NUM> comprises a heater module <NUM> and an aerosol-forming module <NUM>, which are connected to each other using a front cap <NUM>.

In this embodiment the aerosol-forming module <NUM> only comprises one air inlet <NUM> which corresponds to the cold air inlet <NUM> of the first embodiment. Cold ambient air is guided via the dilution air channel <NUM> into the dilution chamber <NUM> to be mixed therein with the aerosol.

In this embodiment the annular hot air channel <NUM> is comprised in the heater module <NUM> and is formed in the annular space between the heater element <NUM> and the housing <NUM> of the heater module <NUM>. The heater module <NUM> comprises an air inlet <NUM>. Air introduced via this air inlet <NUM> is guided along the hot air channel <NUM>. The hot air channel <NUM> is in thermal contact with the heater element <NUM> such that the air guided in the hot air channel <NUM> is heated up by the thermal energy from the heater element <NUM>.

Also in this embodiment, the heater module <NUM> and the aerosol-forming module <NUM> are connected via a threaded front cap <NUM>. The front cap <NUM> has substantially the same form as the front cap <NUM> described with <FIG>. However, the front cap <NUM> of <FIG> is additionally configured to fluidly connect the hot air channel <NUM> and the aerosol-forming chamber <NUM> of the aerosol-forming module <NUM>. For this purpose, the central opening <NUM> in the front cap <NUM> has an inner diameter that is larger than the outer diameter of the capillary tube <NUM>. The hot air stream from the hot air channel <NUM> is passed concentrically with the capillary tube <NUM> through the opening <NUM> of the front cap <NUM>.

The air management in this embodiment is schematically depicted in <FIG>. Capillary tube <NUM> extends from the heater module <NUM> through the opening <NUM> into the aerosol-forming chamber <NUM> of the aerosol-forming module <NUM>. The supersaturated vapor is discharged from the outlet end <NUM> of capillary tube <NUM> into the aerosol-forming chamber <NUM>. Simultaneously the hot air stream from the hot air channel <NUM> is guided through the annular slit between the capillary tube <NUM> and the wall 18a of the front cap <NUM> and is also discharged into the aerosol-chamber <NUM> of the aerosol-forming module <NUM>. The hot air stream forms an envelope for the supersaturated liquid such that premature condensation is prevented. The outer diameter of the capillary tube <NUM> amounts to about <NUM> millimeter. The inner diameter of the opening <NUM> in the front cap <NUM> amounts to about <NUM> millimeters.

<FIG> shows a modification of the embodiment depicted in <FIG>.

Claim 1:
Aerosol-generating device (<NUM>) comprising
a vaporization element having an outlet and being configured to vaporize a liquid,
an airflow passage extending from the outlet (<NUM>) of the vaporization element and being configured to convey vapor to an outlet (<NUM>) of the aerosol-generating device (<NUM>),
a hot air channel (<NUM>) configured to direct heated air towards the outlet (<NUM>) of the vaporization element, and
a dilution air channel (<NUM>) configured to direct ambient air into the device (<NUM>) and to mix the ambient air with the vapor conveyed in the airflow passage to form an aerosol.