Aerosol Generating System

The present disclosure relates to an aerosol generating system for heating an aerosol generating substrate to generate an aerosol for inhalation by a user. Embodiments of the present disclosure relate in particular to an aerosol generating system comprising an aerosol generating device and an aerosol generating article configured for use with the aerosol generating device. The present disclosure is particularly applicable to a portable (hand-held) aerosol generating device.

The popularity and use of reduced-risk or modified-risk devices (also known as aerosol generating devices or vapour generating devices or personal vaporizers) has grown rapidly in recent years as an alternative to the use of traditional tobacco products. These devices heat, rather than burn, an aerosol generating substrate to generate an inhalable aerosol. In some instances, the aerosol generating substrate is provided by an aerosol generating article comprising a porous liquid storage material that stores or holds an aerosol generating liquid.

Currently available aerosol generating devices can use one of a number of different approaches to provide heat to the aerosol generating liquid stored in the porous liquid storage material. One such approach is to employ an induction heating system. In such a device, an induction coil is provided in the device and an inductively heatable susceptor is provided to heat the aerosol generating liquid. Electrical energy is supplied to the induction coil when a user activates the device which in turn generates an alternating electromagnetic field. The susceptor couples with the electromagnetic field and generates heat, which is transferred, for example by conduction, to the aerosol generating liquid stored in the porous liquid storage material and an aerosol is generated as the aerosol generating liquid is heated. Another approach is to employ a resistive heating system, in which current is supplied directly to a heating element. The heating element generates heat, which is transferred, for example by conduction, to the aerosol generating liquid stored in the porous liquid storage material.

In most such aerosol generating devices, the heater operates in a predetermined manner when commanded to start, for example in response to the user pushing a start button or in response to the device determining by means of a puff detector (such as an airflow sensor or microphone) that the user has inhaled a puff through the device. With continued use of the aerosol generating device, the aerosol generating article becomes depleted, as the aerosol generating liquid is consumed, and no longer releases sufficient volatile components to generate an aerosol with acceptable qualities.

It would be desirable to provide an aerosol generating system that enables the amount of aerosol generating liquid remaining in the porous liquid storage material to be monitored, and the present disclosure seeks to address this need.

According to a first aspect of the present disclosure, there is provided an aerosol generating system comprising:

The aerosol generating system enables the amount of aerosol generating liquid remaining in the porous liquid storage material to be monitored.

Optional features will now be set out. These are applicable singly or in any combination with any aspect of the present disclosure.

The electrical load measured by the controller may be a capacitive load or a resistive load.

Possibly, the aerosol generating device includes a power source and the controller is configured to control a supply of power from the power source to the heater based on the measured electrical load. In this arrangement, the amount of heat is adjustable to maximise vapour generation and efficiency. The controller may be configured to terminate the supply of power from the power source to the heater when the measured electrical load exceeds a predetermined threshold.

Possibly, the first electrode is arranged to contact an in use upper face of the aerosol generating article and the second electrode is arranged to contact an in use lower face of the aerosol generating article.

Possibly, the aerosol generating device comprises a mouthpiece portion. The mouthpiece portion may be moveably connected to a device body, wherein the mouthpiece portion is moveable to open and close the heating chamber, wherein the first electrode is provided on an underside of the mouthpiece portion and the second electrode is provided on, or towards, the base of the heating chamber, wherein in a closed condition of the heating chamber the aerosol generating article positioned in the heating chamber is disposed between the first electrode and the second electrode. This arrangement improves electrical contact between the first and second electrodes and the aerosol generating article based on mechanical stress being applied on the aerosol generating article between the mouthpiece portion and base of the heating chamber.

Possibly, the first electrode is configured to correspond in shape and size with the in use upper face of the aerosol generating article and the second electrode is configured to correspond in shape and size with the in use lower face of the aerosol generating article. This arrangement can allow more accurate monitoring of the amount of aerosol generating liquid remaining in each and every portion of the porous liquid storage material because each and every portion is provided between the first and second electrodes.

Possibly, the heater comprises an elongate heating element which projects into the heating chamber and the aerosol generating article comprises an opening in which the elongate heating element is positioned, wherein the elongate heating element is in thermal contact with an inner surface of the porous liquid storage material defined by the opening.

Possibly, the heating chamber includes a chamber wall defining a cavity in which the aerosol generating article is positioned, wherein the first electrode is positioned on the elongate heating element and the second electrode is positioned on the chamber wall.

Alternatively, the first and second electrodes may be positioned on the elongate heating element.

Possibly, the aerosol generating device includes a plurality of pairs of said first and second electrodes and each pair of first and second electrodes is positioned in the heating chamber so that a different portion of the porous liquid storage material is received between each pair of first and second electrodes. In one example, the first electrode of each pair is positioned on the elongate heating element and the second electrode of each pair is positioned on the chamber wall. The first and second electrodes of each pair may be concentric, e.g., with respect to a longitudinal axis of the heating chamber. This arrangement can allow more accurate monitoring of the amount of aerosol generating liquid remaining in each of the different portions of the porous liquid storage material.

Possibly, the controller is configured to measure the electrical load between the first electrode and the second electrode between successive user inhalations to determine the quantity of aerosol generating liquid remaining in the porous liquid storage material based on the measured electrical load. The controller may be configured to determine the remaining number of user inhalations based on the measured electrical load. The number of remaining user inhalations, i.e., ‘puffs’ can thus be determined based on this measurement.

Possibly, the controller is configured to compare the measured electrical load with a reference electrical load determined from a measurement of the electrical load between the first and second electrodes when the porous liquid storage material does not contain an aerosol generating liquid, and to determine the remaining number of user inhalations based on the comparison of the measured electrical load with the reference electrical load.

Possibly, the aerosol generating device comprises a temperature sensor for measuring a temperature of the aerosol generating article, and the controller is configured to adjust the measured electrical load based on the measured temperature. It is known that dielectric response is partly temperature-dependent so measuring the temperature allows an adjustment (i.e., correction/compensation) to be made to the measured electrical load and thereby enables a more reliable determination of the electrical load (and hence the remaining quantity of aerosol generating liquid in the porous liquid storage material) to be made.

The aerosol generating device may be configured so that, during a user inhalation, air flows through the porous liquid storage material. For example, the aerosol generating device may include an air inlet and an air outlet, e.g., in the mouthpiece portion. The aerosol generating device may include an airflow path through the heating chamber, between the air inlet at the air outlet. When a user inhales via the mouthpiece portion, air may flow from the air inlet to the air outlet, along the airflow path through the porous liquid storage material. This airflow through the porous liquid storage material facilitates the release of vapour due to heating and vaporisation of the aerosol generating liquid stored in the porous liquid storage material.

Possibly, the aerosol generating article comprises one or more electrodes arranged to correspond with the position of the first electrode and/or the second electrode. This arrangement improves electrical contact between the first and second electrodes and the aerosol generating article.

Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

Referring initially toandthere is shown diagrammatically a first example of an aerosol generating system. The aerosol generating systemcomprises a first example of an aerosol generating deviceand a first example of an aerosol generating articlefor use with the aerosol generating device. The aerosol generating deviceis electrically operated.

The aerosol generating devicehas a proximal endand a distal endand comprises a device bodywhich includes a power sourceand a controller. The power sourcetypically comprises one or more batteries which could, for example, be inductively rechargeable. The controllerincludes circuitry.

The power sourceand circuitry may be configured to operate at a high frequency in the case of an inductively heated aerosol generating device. The power source and circuitry may be configured to operate at a frequency of between approximately 80 kHz and 500 kHz, possibly between approximately 150 kHz and 250 kHz, and possibly at approximately 200 kHz. The power sourceand circuitry could be configured to operate at a higher frequency, for example in the MHz range. In such examples, the power sourceand circuitry may be configured to operate at a frequency of between approximately 1 and 2 MHz.

The aerosol generating devicecomprises a heating chamber. The heating chambermay have one or more air inlets (not shown). In the illustrated example, the heating chamberis substantially cylindrical.

The heating chamberis positioned at the proximal endof the aerosol generating device. The aerosol generating devicemay include a plurality of air inlets (not shown) formed in the device bodywhich deliver air to the heating chambervia the air inlets.

In, the aerosol generating articleis shown positioned in the heating chamberof the aerosol generating device. In, for illustrative purposes the aerosol generating articleis shown prior to being positioned in the heating chamberof the aerosol generating device.

The aerosol generating articleis a consumable article and may be regarded as a capsule or cartridge. In the illustrated example, the aerosol generating articleis substantially cylindrical. The circular cross-section facilitates handling of the aerosol generating articleby a user and insertion of the aerosol generating articleinto a heating chamberof the aerosol generating device. It should, however, be noted that a circular cross-section is not essential and that other cross-sectional shapes, such as square, hexagonal, or tetrahedral, are within the scope of the present disclosure.

The aerosol generating articlecomprises a porous liquid storage materialthat stores or holds an aerosol generating liquid. Accordingly, the aerosol generating articlecomprises a porous liquid storage materialfor storing an aerosol generating liquid. The aerosol generating liquid may comprise an aerosol-forming substance such as propylene glycol and/or glycerol and may contain other substances such as nicotine and acids. The aerosol generating liquid may also comprise other additives and ingredients, such as flavourings, e.g., tobacco, menthol, or fruit flavour. The aerosol generating liquid may comprise a suspension of tobacco within a liquid. The term “aerosol generating liquid” used herein includes any non-solid material, e.g., a semi-liquid material such as a gel or a wax, capable of generating a vapour or aerosol when heated.

The porous liquid storage materialtypically comprises a high retention material, for example a porous ceramic, which enables the aerosol generating liquid to be readily absorbed and retained by the porous liquid storage materialwithout any leakage. The porous ceramic material is a high retention material and, thus, allows a sufficient quantity of aerosol generating liquid to be stored for a desired period of use. The porous liquid storage materialtypically comprises a non-inductively heatable material, for example an electrically non-conductive and non-magnetic material, meaning that it is not inductively heated in the presence of an electromagnetic field.

The porous liquid storage materialmay comprise a self-supporting material.

The aerosol generating deviceincludes a mouthpiece portionincluding an outlet (not shown). The mouthpiece portionis moveably connected to the device body. The mouthpiece portionis moveable to open and close the heating chamber. In the illustrated example, the mouthpiece portionis connected to the device bodyby a hinged connection, but any kind of connection may be used, such as a snap-fit connection, a bayonet connection, or a screw fitting.

The aerosol generating devicefurther comprises a heaterarranged for heating and vaporising the stored aerosol generating liquid.

In some examples, the heater comprises a heating elementwhich surrounds the porous liquid storage material. The heating elementis mounted on, or defined by, a side wall(i.e., a chamber wall) of the heating chamberand thermally contacts an outer surfaceof the porous liquid storage material. Accordingly, the heating elementis in thermal contact with the outer surfaceof the porous liquid storage material. This ensures that an efficient and uniform transfer of heat, e.g., by conduction, is achieved from the heating elementto the porous liquid storage material. The chamber wallof the heating chamberdefines a cavityin which the aerosol generating articleis positioned.

In some examples, the heating elementmay be a resistance heating element. In such examples, the resistance heating element is operatively connected to the power sourceand controller. As will be understood by one of ordinary skill in the art, when an electric current is passed through the resistance heating element, heat is generated by virtue of Joule heating. Heat from the resistance heating element is transferred to the porous liquid storage material, primarily by conduction but possibly also by radiation and/or convection. The aerosol generating liquid stored in the porous liquid storage materialis thereby heated to a temperature at which one or more volatile components are released, causing the aerosol generating liquid to be vaporised and a vapour to be generated.

In other examples, the heating elementmay be an inductively heatable susceptor, which typically comprises a metal, and is inductively heatable in the presence of a time varying (alternating) electromagnetic field.

The inductively heatable susceptor may comprise an electrically conductive material and may comprise a metal. The metal is typically selected from the group consisting of stainless steel and carbon steel. The inductively heatable susceptor could, however, comprise any suitable material including one or more, but not limited, of aluminium, iron, nickel, stainless steel, carbon steel, and alloys thereof, e.g., Nickel Chromium or Nickel Copper. With the application of an electromagnetic field in its vicinity during use of the aerosol generating articlein an aerosol generating device, the inductively heatable susceptor may generate heat due to eddy currents and/or magnetic hysteresis losses resulting in a conversion of energy from electromagnetic to heat.

In such examples, the aerosol generating devicefurther comprises an induction heating arrangement (not shown) for generating an alternating electromagnetic field that is capable of penetrating (i.e., coupling with) the inductively heatable susceptor to thereby inductively heat the inductively heatable susceptor. The induction heating arrangement comprises a substantially helical induction coil. The induction coil has a circular cross-section and extends around the substantially cylindrical heating chamber. The induction coil may, for example, extend around an outer wall of the heating chamber. The induction coil may have a shape which substantially corresponds to the shape of the heating chamber. For example, the induction coil may be a helical coil.

The induction coil may comprise a Litz wire or a Litz cable. It will, however, be understood that other materials could be used.

The induction coil can be energised by the power sourceand controller. The controllerincludes, amongst other electronic components, an inverter which is arranged to convert a direct current from the power sourceinto an alternating high-frequency current for the induction coil.

The induction coil may be arranged to operate in use with a fluctuating electromagnetic field having a magnetic flux density of between approximately 20 mT and approximately 2.0 T at the point of highest concentration.

As will be understood by one of ordinary skill in the art, when the aerosol generating articleis positioned in the heating chamberas shown inand the induction coil is energised during use of the aerosol generating system, an alternating and time-varying electromagnetic field is produced. This couples with and penetrates the inductively heatable susceptor and generates eddy currents and/or magnetic hysteresis losses in the susceptor causing it to heat up. The heat is then transferred from the inductively heatable susceptor to the porous liquid storage material, primarily by conduction but possibly also by radiation and/or convection. The aerosol generating liquid stored in the porous liquid storage materialis thereby heated to a temperature at which one or more volatile components are released, causing the aerosol generating liquid to be vaporised and a vapour to be generated.

Accordingly, the heatermay comprise an inductively heatable susceptor and the aerosol generating devicemay further comprise an induction heating arrangement for generating an alternating electromagnetic field for penetrating the inductively heatable susceptor to thereby inductively heat the inductively heatable susceptor.

By using an inductively heatable susceptor as the heating elementin combination with an induction heating arrangement, efficient and rapid heating of the porous liquid storage materialis achieved, thereby improving both the aerosol generation capabilities and the energy efficiency of the aerosol generating device.

The vaporisation of the aerosol generating liquid stored in the porous liquid storage materialis facilitated by the addition of air from the surrounding environment through the air inlets. The vapour generated by heating the aerosol generating liquid is released from the porous liquid storage materialthanks to its porosity and may cool and condense to form an aerosol.

The vapour or aerosol passes through the outlet in the mouthpiece portionand is inhaled by a user. It will be understood that the flow of air through the aerosol generating device, i.e., from the air inlets, along an airflow path through the porous liquid storage material, and through the outlet of the mouthpiece portion, is aided by negative pressure created by a user drawing air from the outlet side of the aerosol generating devicethrough the mouthpiece portion.

Prior to using the aerosol generating system, a user must first pivot the mouthpiece portionto the open position shown inand insert an aerosol generating articleinto the heating chamber. The user can then pivot the mouthpiece portionto the closed position as shown inso that the aerosol generating systemis ready for use. The aerosol generating devicecan then be activated (e.g., by a button press) to activate the heaterin the manner described above to generate an inhalable aerosol.

With continued use of the aerosol generating device, the aerosol generating articlebecomes depleted, as the aerosol generating substrate liquid is consumed, and no longer releases sufficient volatile components to generate an aerosol with acceptable qualities. When the aerosol generating articlebecomes depleted it can be easily removed from the heating chamberafter pivoting the mouthpiece portionto the open position, and a replacement aerosol generating articlecan be inserted into the heating chamberin its place.