Patent Publication Number: US-2023145098-A1

Title: Aerosol Generating Device with Battery Monitoring Arrangement

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to an aerosol generating device, and more particularly to an aerosol generating device for heating an aerosol generating substance to generate an aerosol for inhalation by a user. 
     TECHNICAL BACKGROUND 
     Devices which heat, rather than burn, an aerosol generating substance to produce an aerosol for inhalation have become popular with consumers in recent years. Such devices can use one of a number of different approaches to provide heat to the aerosol generating substance. 
     One approach is to provide an aerosol generating device which employs a resistive heating system. In such a device, a resistive heating element is provided to heat the aerosol generating substance and thereby generate a vapour which typically cools and condenses to form an aerosol for inhalation by a user of the device. 
     Another approach is to provide an aerosol generating device which employs an induction heating system. In such a device, an induction coil and a susceptor are provided. 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 substance thereby generating a vapour which typically cools and condenses to form an aerosol for inhalation by a user of the device. 
     Whichever approach is used to heat the aerosol generating substance, it may be preferable for the aerosol generating device to include a rechargeable battery to supply the required electrical power to the resistive heating element or the induction coil. The use of a rechargeable battery may, however, have certain drawbacks which the present disclosure seeks to mitigate. 
     SUMMARY OF THE DISCLOSURE 
     According to a first aspect of the present disclosure, there is provided an aerosol generating device comprising:
         a housing defining a cavity for receiving an aerosol generating substance;   a controller;   a rechargeable battery positioned in the housing;   wherein the controller is configured to detect expansion of the rechargeable battery in the housing.       

     The aerosol generating device is adapted to heat the aerosol generating substance, without burning the aerosol generating substance, to volatise at least one component of the aerosol generating substance and thereby generate a vapour which cools and condenses to form an aerosol for inhalation by a user of the aerosol generating device. 
     In general terms, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour can be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms ‘aerosol’ and ‘vapour’ may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user. 
     Detection of physical expansion of the rechargeable battery is readily achieved by the controller, thereby avoiding potential damage to the aerosol generating device, for example by allowing use of the device to be discontinued and/or by enabling action to be taken to replace the rechargeable battery and/or by enabling the controller to modify how the rechargeable battery is charged and/or discharged. 
     The aerosol generating device may include an electrically conductive component having an electrical characteristic which varies in response to expansion of the rechargeable battery in the housing. The electrically conductive component may be positioned in the housing such that the electrically conductive component is deformed by expansion of the rechargeable battery in the housing. The variation of the electrical characteristic of the electrically conductive component provides a reliable indication that there is physical expansion of the rechargeable battery. 
     The electrical characteristic of the electrically conductive component may vary based on the deformation of the electrically conductive component. The extent of the physical expansion of the rechargeable battery can, thus, be determined based on the variation of the electrical characteristic. For example, a small variation in the electrical characteristic may indicate that there is a small amount of physical expansion of the rechargeable battery which may not warrant intervention or replacement, whereas a large variation in the electrical characteristic may indicate that there is a large amount of physical expansion of the rechargeable battery which may warrant intervention or replacement. 
     The controller may be configured to detect expansion of the rechargeable battery based on a detected variation of the electrical characteristic of the electrically conductive component. The controller can thus reliably detect any physical expansion of the rechargeable battery based on the variation of the electrical characteristic of the electrically conductive component. 
     The rechargeable battery may comprise one or more rechargeable cells contained within a battery housing. The battery housing may have any suitable geometry, and may for example be substantially cylindrical, substantially button-shaped or coin-shaped, or substantially rectangular. These housing geometries are given purely by way of example, and it will be apparent to one of ordinary skill in the art that other housing geometries could be employed and are entirely within the scope of the present disclosure. 
     The electrical characteristic may include an electrical resistance of the electrically conductive component and the controller may be configured to monitor the electrical resistance of the electrically conductive component. With this arrangement, the controller may be configured to detect physical expansion of the rechargeable battery based on a detected change in the electrical resistance of the electrically conductive component. 
     The electrical characteristic may include an electrical conductivity of the electrically conductive component and the controller may be configured to detect a break in the electrical conductivity. For example, the electrically conductive component may be configured to be pulled apart and to mechanically fail under tension in the event that the rechargeable battery expands. With this arrangement, the controller may be configured to detect physical expansion of the battery based on a detected break in the electrical conductivity of the electrically conductive component. 
     The electrically conductive component may extend around at least part of an outer surface of the rechargeable battery. The structure of the aerosol generating device may be simplified. 
     The electrically conductive component may extend substantially along the whole perimeter (e.g. circumference) of the rechargeable battery. This may allow any expansion of the rechargeable battery to be reliably detected. 
     The electrically conductive component may extend around an outer surface of the rechargeable battery over a distance which is greater than a perimeter (e.g. circumference) of the rechargeable battery. Opposite ends of the electrically conductive component may be displaced relative to each other in an axial direction of the rechargeable battery. In one example, the electrically conductive component may be wound diagonally or helically around the rechargeable battery. In another example, one or more portions of the electrically conductive component may extend substantially in an axial direction of the rechargeable battery. With these arrangements, the electrically conductive component may cover a larger surface area of the rechargeable battery, thereby enabling expansion of the rechargeable battery to be more reliably detected. 
     The electrically conductive component may be disposed on an outer surface of the rechargeable battery. For example, the electrically conductive component could be coated, adhered, printed, deposited or otherwise manufactured onto the outer surface of the rechargeable battery. The direct and intimate contact between the electrically conductive component and the outer surface of the rechargeable battery may facilitate the detection of expansion of the rechargeable battery and may allow the structure of the aerosol generating device to be simplified. 
     The electrically conductive component may be positioned adjacent to an outer surface of the rechargeable battery. In this example, the electrically conductive component may be an integral component part of the aerosol generating device. For example, the electrically conductive component may be disposed on the housing of the aerosol generating device. 
     The electrically conductive component may comprise an electrically conductive track or an electrically conductive strip. 
     The controller may be configured to generate an alert upon detecting expansion of the rechargeable battery. This may allow a user of the aerosol generating device to take appropriate action, for example by ceasing use of the device and possibly removing and replacing the rechargeable battery. 
     The aerosol generating device may include a heater electrically connected to the rechargeable battery and arranged to heat an aerosol generating substance positioned in the cavity and the controller may be configured to electrically disconnect the heater from the rechargeable battery upon detecting expansion of the rechargeable battery. Further use of the device, and potential further physical expansion of the rechargeable battery, may be prevented. This may minimise the risk of the aerosol generating device being physically damaged by preventing continued use. 
     The heater may comprise a resistive heater. The resistive heater may comprise a resistive heating element. The resistive heating element may comprise an electrically resistive material. Examples of suitable electrically resistive materials include, but are not limited to, metals, metal alloys, electrically conductive ceramics, for example tungsten and alloys thereof, and composite materials comprising a metallic material and a ceramic material. 
     The heater may comprise an induction coil arranged to generate an alternating electromagnetic field for inductively heating an induction heatable susceptor. 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 may extend around the cavity. 
     The induction coil could be substantially helical in shape. The circular cross-section of a helical induction coil may facilitate the insertion of an aerosol generating substance, or for example an aerosol generating article containing the aerosol generating substance and optionally one or more induction heatable susceptors, into the cavity and ensure uniform heating of the aerosol generating substance. 
     The induction heatable susceptor(s) may comprise one or more, but not limited, of aluminium, iron, nickel, stainless steel and alloys thereof, e.g. Nickel Chromium or Nickel Copper. With the application of an electromagnetic field in its vicinity, the susceptor(s) may generate heat due to eddy currents and magnetic hysteresis losses resulting in a conversion of energy from electromagnetic to heat. 
     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. 
     The controller may include electronic circuitry. The rechargeable battery and the electronic circuitry may be configured to operate at a high frequency. The rechargeable battery and the electronic 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 rechargeable battery and the electronic circuitry could be configured to operate at a higher frequency, for example in the MHz range, depending on the type of inductively heatable susceptor that is used. 
     The aerosol generating substance may be any type of solid or semi-solid material. Example types of aerosol generating solids include powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut leaves, cut filler, porous material, foam material or sheets. The aerosol generating substance may comprise plant derived material and in particular, may comprise tobacco. It may advantageously comprise reconstituted tobacco. 
     The aerosol generating substance may be circumscribed by a paper wrapper and may, thus, be embodied as an aerosol generating article. The aerosol generating article may be formed substantially in the shape of a stick. The aerosol generating article may include a filter, for example comprising cellulose acetate fibres. The filter may be in abutting coaxial alignment with the aerosol generating substance. 
     The aerosol generating substance may be arranged inside a shell and may, thus, be embodied as an aerosol generating article. The shell may be an air-permeable shell and may comprise a material which is electrically insulating and non-magnetic. The shell may comprise an air-permeable material, for example a porous material. The material may have a high air permeability to allow air to flow through the material with a resistance to high temperatures. Examples of suitable air-permeable materials include cellulose fibres, paper, cotton and silk. The air-permeable material may also act as a filter. Alternatively, the shell may comprise a material that is not air permeable, e.g., a non-porous material, but which includes perforations or openings to allow air to flow through the shell. 
     The aerosol generating substance may comprise an aerosol-former. Examples of aerosol-formers include polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. Typically, the aerosol generating substance may comprise an aerosol-former content of between approximately 5% and approximately 50% on a dry weight basis. In some embodiments, the aerosol generating substance may comprise an aerosol-former content of between approximately 10% and approximately 20% on a dry weight basis, and possibly approximately 15% on a dry weight basis. 
     In another example, the aerosol generating substance may be the aerosol-former itself. The aerosol generating substance may, therefore, be a liquid. In this case, the aerosol generating device may include a liquid transfer element (e.g. a wick) associated with the heater which allows the liquid to be vaporized by the heater and allows a vapour to be formed and released/emitted from the liquid transfer element, the vapour subsequently cooling and condensing to form an aerosol suitable for inhalation by a user of the aerosol generating device. 
     Upon heating, the aerosol generating substance may release volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco flavouring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagrammatic cross-sectional view of an example of an aerosol generating device including a rechargeable battery and an electrically conductive component which extends around the outer surface of the battery; 
         FIGS.  2  and  3    are diagrammatic cross-sectional views along the line A-A in  FIG.  1   , showing the rechargeable battery respectively in an unexpanded state and an expanded state; 
         FIGS.  4  and  5    are diagrammatic views similar to  FIGS.  2  and  3    of an alternative example in which an electrically conductive component extends around part of the outer surface of the rechargeable battery; and 
         FIG.  6    is a diagrammatic cross-sectional view similar to  FIG.  1    showing only the rechargeable battery and an electrically conductive component which extends helically around an outer surface of the rechargeable battery. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings. 
     Referring initially to  FIGS.  1  to  3   , there is shown diagrammatically an example of an aerosol generating system  1 . The aerosol generating system  1  comprises an aerosol generating device  10  and an example of an aerosol generating article  24 . The aerosol generating device  10  has a proximal end  12  and a distal end  14  and comprises a housing  16  which defines a cavity  18 . The housing  16  includes one or more air inlets  19  for supplying air to the cavity  18 . The aerosol generating device  10  further includes a power source in the form of a rechargeable battery  20 , and a controller  22 . Although only one rechargeable battery  20  is illustrated in  FIG.  1   , it will be understood that the power source could comprise a plurality of rechargeable batteries  20  and that the or each rechargeable battery  20  may, for example, be inductively rechargeable. 
     The aerosol generating device  10  is generally cylindrical and the cavity  18  defined by the housing  16  is also cylindrical and takes the form of a cylindrical heating compartment. The cavity  18  is arranged to receive a correspondingly shaped generally cylindrical or rod-shaped aerosol generating article  24  comprising an aerosol generating substance  26 . The aerosol generating article  24  is a disposable article which may, for example, contain tobacco as the aerosol generating substance  26 . The aerosol generating article  24  has first and second ends  28 ,  30  and comprises a paper wrapper  32  surrounding the aerosol generating substance  26 . The aerosol generating article  24  also comprises a filter  34  at the first end  28  which is in abutting coaxial alignment with the aerosol generating substance  26  and the paper wrapper  32 . The filter  34  acts as a mouthpiece and comprises an air-permeable plug, for example comprising cellulose acetate fibres. Both the paper wrapper  32  and the filter  34  are overwrapped by an outer wrapper  36  typically comprising tipping paper. In an alternative example not illustrated in the drawings, the filter  34  could be omitted and instead the aerosol generating device  10  could include an integrated mouthpiece. 
     The aerosol generating device  10  includes a heater  37  for heating the aerosol generating substance  26  without burning the aerosol generating substance  26 . In the illustrated embodiment, the heater  37  comprises a resistive heating element  38  which is positioned radially outwardly of the cavity  18  and which extends around the cavity  18 . 
     During operation of the aerosol generating system  1 , an electric current is supplied to the resistive heating element  38  causing it to heat up. The heat from the resistive heating element  38  is transferred to the aerosol generating substance  26  positioned in the cavity  18 , for example by conduction, radiation and convection, to heat the aerosol generating substance  26  and thereby generate a vapour which cools and condenses to form an aerosol for inhalation by a user of the aerosol generating system  1 . The vaporisation of the aerosol generating substance  26  is facilitated by the addition of air from the surrounding environment through the air inlets  19 . 
     The aerosol generating device  10  includes an electrically conductive component  40  in the form of an electrically conductive track  42 . In the example illustrated in  FIGS.  1  to  3   , the rechargeable battery  20  is substantially circular in cross-section and the electrically conductive track  42  extends circumferentially around an outer surface  20   a  of the rechargeable battery  20 , substantially around the whole circumference. As will be apparent from the cross-sectional view of  FIG.  2    which shows the rechargeable battery  20  in an unexpanded state, the electrically conductive track  42  is positioned adjacent to the outer surface  20   a  of the rechargeable battery  20 . More particularly, the electrically conductive track  42  is disposed on the housing  16  inside a battery compartment in which the rechargeable battery  20  is positioned. In another example (not illustrated), the electrically conductive track  42  may be disposed on the outer surface  20   a  of the rechargeable battery  20 , for example by being coated, adhered, printed, deposited or otherwise manufactured onto the outer surface  20   a  of the rechargeable battery  20 . In both cases, the electrically conductive track  42  is arranged so that when the rechargeable battery  20  is in an unexpanded state as shown in  FIG.  2   , the electrically conductive track  42  remains intact and electrically conductive. 
     In the example illustrated in  FIGS.  1  to  3   , the electrically conductive track  42  is formed of a material which is substantially inextensible. Thus, if the rechargeable battery  20  expands by a predetermined amount or beyond a predetermined threshold, the electrically conductive track  42  is pulled apart and breaks under tension, for example at the point designated A in  FIG.  3   , resulting in a break in the electrical conductivity of the electrically conductive track  42 . The controller  22  can be configured to detect the break in the electrical conductivity of the electrically conductive track  42  and to thereby detect expansion of the rechargeable battery  20  in the housing  16 . 
     In another example illustrated in  FIGS.  4  and  5   , the electrically conductive track  42  extends around only part of the outer surface  20   a  of the rechargeable battery  20 . The electrically conductive track  42  comprises an extensible material which is caused to mechanically extend under tension when the rechargeable battery  20  expands in the housing  16 . The extension of the electrically conductive track  42  due to expansion of the rechargeable battery  20  is apparent from a comparison of  FIGS.  4  and  5   . The electrically conductive track  42  has a resistance which changes (e.g. increases or decreases) as it is deformed, and in particular as it is extended. The controller  22  can be configured to detect the change in the resistance of the electrically conductive track  42  and to thereby detect expansion of the rechargeable battery  20  in the housing  16 . 
     In some embodiments, the controller  22  may be configured to generate an alert upon detecting expansion of the rechargeable battery  20 , for example based on a detected break in the electrical conductivity of the electrically conductive track  42  ( FIGS.  2  and  3   ) or based on a detected change in the resistance of the electrically conductive track  42  ( FIGS.  4  and  5   ). The alert may notify a user of the aerosol generating device  10  that expansion of the battery  20  has been detected, for example enabling the user to cease use of the device  10  and/or to replace the rechargeable battery  20 . Alternatively or in addition, the controller  20  may be configured to electrically disconnect the resistive heating element  38  from the rechargeable battery  20  upon detecting physical expansion of the rechargeable battery  20  and/or to modify the charge and/or discharge characteristics of the rechargeable battery  20 , for example to minimise the rate of further expansion and to prolong the useful life of the rechargeable battery  20 . 
     Referring now to  FIG.  6   , there is shown an alternative example of an electrically conductive track  42  which extends helically around the outer surface  20   a  of the rechargeable battery  20 . In this alternative example, the electrically conductive track  42  extends around the outer surface  20   a  by a total distance which is greater than the circumference of the rechargeable battery  20 . As noted above, arrangements in which the electrically conductive track  42  extends around the outer surface  20   a  of the rechargeable battery  20  by a distance which is greater than its circumference may allow expansion of the rechargeable battery  20  to be more reliably detected because the electrically conductive track  42  covers a larger surface area of the rechargeable battery  20 . 
     Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claim. Thus, the breadth and scope of the claim should not be limited to the above-described exemplary embodiments. 
     Any combination of the above-described features in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context. 
     Unless the context clearly requires otherwise, throughout the description and the claim, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.