WO2023241903A1

WO2023241903A1 - Dc capsule with preheating

Info

Publication number: WO2023241903A1
Application number: PCT/EP2023/064386
Authority: WO
Inventors: Grzegorz Aleksander PILATOWICZ; Peter LOVEDAY
Original assignee: Jt International Sa
Priority date: 2022-06-13
Filing date: 2023-05-30
Publication date: 2023-12-21

Abstract

A capsule for use with an electronic vapor inhaler, the capsule comprising a capsule body accommodating a liquid to be vaporized by heating; a vaporization chamber releasing vaporized liquid toward a mouthpiece; a pair of electrodes arranged in the vaporization chamber for leading a dc current through a volume of the liquid in a space between the electrodes; and a pre-heating element for heating the liquid to a pre-heating temperature in at least a part of the volume of the liquid.

Description

DC capsule with preheating

[ Technical Field]

The present invention relates to an aerosol generation unit and disposable capsule thereof . In particular, the present invention relates to mechanisms for generating an aerosol in the speci fic context of aerosol generation devices , such as inhalers , e-cigarettes , and the like .

[Background]

By vapori zing a liquid an aerosol is generated which can then be inhaled by a user . Vapori zation arrangements are typically provided in electronic cigarettes , electronic air fresheners or medical inhalers . The heating engines of conventional vapori zation arrangements are based on resistive heating in which electrical energy is delivered to a resistive heater such as a coil or thin wire . The resistive heater converts the electrical energy into heat which is then trans ferred to a wick attached to the resistive heater . Typical material s for wicks include ceramic, such as Zeolite Y, and cotton . Resistive heaters are typically made from nichrome with a resistance of the order of 1 Q . The wick is heated to a high temperature , typically in the range of 150 to 250 ° C, such that liquid, which is absorbed by the wick, is vapori zed . The generated aerosol can then be inhaled by a user, for example , by "puf fing" that is by generating an air flow by sucking . The air flow may also be generated by natural convection or with a fan .

However, such wick-based vapori zation arrangements may have several problems . Vapori zation arrangements using a cotton wick run the risk of "dry puf fs" , which occur when there i s not enough liquid available such that the resistive heater is trans ferring heat to a dry wick . In this case , the wick can reach very high temperatures and emit potentially increased quantities of undesired components . Furthermore , "dry puf fs" may be an unpleasant experience for the user inhaling these substances .

Another problem of wick-based vapori zation arrangements is that a residue in the liquid can clog the ceramic or cotton wick, thereby hindering the flow of liquid . The type of residue depends on the formulation of the liquid . A typical residue is tobacco . The residue may get burned after a limited time period, thereby generating smoke which again leads to an unpleasant experience for the user . Furthermore , the wick may be damaged such that the wick-based vapori zation arrangement cannot be used anymore .

[ Summary]

The novel capsule for use in an electronic vapor inhaler proposed in the present disclosure is based on the ohmic heating principle . The capsule together with the electronic vapor inhaler forms the vapori zation arrangement for generating aerosol to be inhaled by a user . Ohmic heating means that an electric current flows directly through a liquid in a space between a pair of electrodes . In this case , the liquid can be considered as an electric resistance in which heat is directly generated . The heating of the liquid is therefore achieved more ef ficiently compared to conventional approaches using resistive heaters .

Furthermore , the proposed capsule does not require any wicking material . I f there is no liquid in the space between the electrodes , there is no flow of electric current and the problem of "dry puf fs" can be eliminated . Additionally, this wickless design may also eliminate the problem of clogging of the wick . Hence , user experience and safety of the vapori zation arrangement may be improved .

By omitting the resistive heater and wick, the number of components of the proposed capsule may be reduced compared to conventional implementations , which may result in a reduction of the overall manufacturing costs and in a longer service li fe of the vapori zation arrangement .

Typically, the liquid used in conventional capsules for use with an electronic vapor inhaler has a relatively high resistance at temperature below 25 ° C . This makes it di f ficult to vapori ze the liquid with an amount of power which allows for nearly instantaneous vapori zation without increasing the input voltage of the heater above a safe contact level of 60 V . The maximal amount of power delivered by a conventional electronic vapor inhaler may be limited . When the safe contact voltage level is reached additional and costly measures such as additional insulation of the contacts and wiring may be required .

In order to address this technical problem, the present invention employs a pre-heating element to heat the liquid in order to lower the resistance of the liquid and enable ohmic heating of the liquid without increasing the input voltage of the heater above the safe contact level . One embodiment relates to a capsule for use with an electronic vapor inhaler, the capsule comprising a capsule body accommodating a liquid to be vapori zed by heating; a vapori zation chamber releasing vapori zed liquid toward a mouthpiece ; a pair of electrodes arranged in the vapori zation chamber for leading a de current through a volume of the liquid in a space between the electrodes ; and a pre-heating element for heating the liquid to a pre-heating temperature in at least a part of the volume of the liquid .

[Brief description of the drawings ]

Embodiments of the present invention, which are presented for better understanding the inventive concepts , but which are not to be seen as limiting the invention, will now be described with reference to the figures in which :

Fig . 1A shows a front view of a capsule for use with an electronic vapor inhaler according to an embodiment of the present invention wherein the pre-heating element is omitted;

Fig . IB shows a side view of a capsule for use with an electronic vapor inhaler according to an embodiment of the present invention wherein the pre-heating element is omitted;

Fig . 2 shows a perspective view of the capsule disconnected from the electronic vapor inhaler ;

Fig . 3 shows a schematic of an internal layout of a capsule according to an embodiment of the present invention wherein the pre-heating element is omitted; Fig . 4 shows a schematic of an internal layout of a capsule according to an embodiment of the present invention wherein the pre-heating element is omitted;

Fig . 5A shows a schematic of an internal layout of a capsule with a compact design according to an embodiment of the present invention wherein the pre-heating element is omitted;

Fig . 5B shows a schematic of an internal layout of a capsule with a compact design further comprising a sediment trap according to an embodiment of the present invention wherein the pre-heating element is omitted;

Fig . 6 shows a schematic of an internal layout of a capsule with a compact design further comprising a gauze and a recess structure for channeling the air flow according to an embodiment of the present invention wherein the pre-heating element is omitted;

Fig . 7 shows a plot of the conductivity of the liquid with respect to the temperature of the liquid;

Fig . 8A shows a section of the internal layout of the capsule according to Fig . 3 , the section comprising the liquid conduit and the vapori zation chamber, including a preheating element ; Fig . 8B shows a section of the internal layout of the capsule according to Fig . 3 , the section comprising the liquid conduit and the vapori zation chamber, including a preheating element ;

Fig . 9A shows from an angled point of view a pair of electrodes according to an embodiment of the present invention;

Fig . 9B shows from a side view a pair of electrodes according to an embodiment of the present invention;

Fig . 10 shows from a side view a pair of electrodes with a PTC resistor in between according to an embodiment of the present invention;

Fig . 11 shows a plot of the resistance of the PTC resistor with respect to its temperature ;

Fig . 12 shows a circuit diagram compri sing a de power source and a parallel circuit comprising the PTC resistor and a resistor given by a liquid in a vapori zation volume ;

Fig . 13 shows plots of the expected res istance of the PTC resistor and of the resistor given by the liquid in the space between the electrodes with respect to the temperature of that liquid;

Fig . 14A shows from a side view a pair of electrodes with a bi-metallic strip in between according to an embodiment of the present invention;

Fig . 14B shows from a side view the pair of electrodes with a bi-metallic strip in between according to an embodiment of the present invention;

Fig . 15 shows plots of the temperature of the liquid, the current through the bi-metallic strip and the current through the liquid in the space between the electrodes with respect to time ;

Fig . 16 shows from a side view a pair of electrodes with a coil outside the space between the electrodes according to an embodiment of the present invention;

Fig . 17A shows from a side view a pair of electrodes with a coil in between according to an embodiment of the present invention;

Fig . 17B shows from a side view one electrode of the pair of electrodes with the coil on top according to an embodiment of the present invention; and

Fig . 18 shows plots of the temperature of the liquid, the electric power through the coil and the electric power through the liquid in the vapori zation volume with respect to time ; [ Detailed description]

The present invention shall now be described in conj unction with speci fic embodiments . The speci fic embodiments serve to provide the skilled person with a better understanding but are not intended to in any way restrict the scope of the invention, which is defined by the appended claims . In particular, the embodiments described independently throughout the description can be combined to form further embodiments to the extent that they are not mutually exclusive .

Fig . 1A and IB show a capsule 1 for use with an electronic vapor inhaler 17 , not shown in Fig . 1A and IB, from a front and side view, respectively . The capsule 1 comprises a capsule body 7 accommodating a liquid 8 , not shown in Fig . 1A and IB, to be vapori zed by heating . The capsule 1 further comprises a vapori zation chamber 3 in which the liquid 8 is to be vapori zed . Vapori zed liquid, also referred to as aerosol 2 , not shown in Fig . 1A and IB, is released toward a mouthpiece 14 of the capsule 1 . The capsule 1 further comprises a pair of electrodes 4a, 4b (not shown) arranged in the vapori zation chamber 3 for leading a de current through a volume of the liquid 8 in a space between the electrodes 5 . The space between the electrodes is also referred to as the vapori zation volume 5 . The capsule 1 further comprises a preheating element 16 , not shown in Fig . 1A and IB, for heating the liquid 8 to a pre-heating temperature in at least a part of the volume of the liquid 8 .

The capsule 1 is designed to be used with an electronic vapor inhaler 17 . The capsule 1 may be adapted to be inserted into the electronic vapor inhaler 17 in order to supply the pair of electrodes 4a, 4b with the de current such that the liquid 8 in the vapori zation volume 5 is heated via ohmic heating as the de current is lead through the liquid 8 in the vapori zation volume 5 . The capsule 1 may be adapted to be ej ected from the electronic vapor inhaler 17 , for example , when the liquid 8 is depleted . The capsule 1 may then be refilled or disposed .

Fig . 2 shows a perspective view of the capsule 1 disconnected from the electronic vapor inhaler 17 . The electronic vapor inhaler 17 may comprise a de power source , such as a battery, for generating the de current for use by the inserted capsule 1 . The capsule 1 may comprise a first set of contacts I la for applying the de current provided by the electronic vapor inhaler 17 to the pair of electrodes 4a, 4b .

The vapori zation chamber 3 may be arranged such that it receives the liquid 8 through a liquid conduit 6 . In Fig . IB the liquid conduit 6 is shown as a rectangular hole in the enclosure of the vapori zation chamber 3 which serves as the inlet for the liquid 8 flowing into the vapori zation chamber 3 . The vapori zation chamber 3 may further be arranged such that it receives intake air from an air inlet 18 . The air inlet 18 may be arranged such that intake air may be drawn in from outside the capsule body 8 . The vapori zation chamber 3 may further be arranged to release aerosol 2 through a vapor conduit 9 toward the mouthpiece 14 . This way, the vapori zation chamber 3 may be connected via a vapor conduit 9 to the mouthpiece 14 and a user may generate a flow of air by sucking on the mouthpiece 14 such that air is drawn into the vapori zation chamber 3 and a mix of intake air and aerosol 2 , generated by vapori zing the liquid 8 , is discharged toward the mouthpiece 14 to be inhaled by the user . Alternatively, the flow of air may be generated by natural convection, with a fan or similar means of generating a pressure di f ference . The capsule body 7 may serve as a reservoir for the liquid 8 . The capsule body 7 may be provided as a transparent enclosure , such as glass or plexiglass , so that the user may observe the fill level of the liquid 8 .

Fig . 3 shows a schematic of an internal layout of a capsule 1 according to an embodiment of the invention in a cross- sectional view . Here , the liquid 8 is supplied to the vapori zation chamber 3 via the liquid conduit 8 . An electric de potential is generated between the pair of electrodes 4a , 4b such that one electrode of the pair of electrodes 4a, 4b is positively charged while the other electrode is negatively charged . The de current flow passes through the liquid 8 in the vapori zation volume 5 , that is in the space between the electrodes 4a, 4b . This way, the liquid 8 can be heated via ohmic heating to its boiling temperature to generate the aerosol 2 . The capsule 1 further comprises a pre-heating element 16 , not shown in Fig . 3 , which is arranged to heat at least a part of the volume of the liquid in the vapori zation volume 5 to a pre-heating temperature . The arrangement of the pre-heating element 16 within the capsule 1 will be described with reference to Figs . 8A and 8B .

A liquid conduit 6 may be arranged to supply, from the capsule body 7 , the liquid 8 to the vapori zation chamber 3 . A vapor conduit 9 may be arranged to discharge the aerosol 2 , generated in the vapori zation volume 5 , from the vapori zation chamber 3 . The air flow 10 , indicated by the arrow in Fig . 3 , illustrates the direction in which the aerosol 2 may be discharged to then be inhaled by the user .

The capsule 1 is designed to be used with an electronic vapor inhaler 17 such as an electronic cigarette or a medical inhaler . Depending on the application, the capsule 1 may be adapted in its size, shape and capacity to fulfill the given requirements such as, for example, requirements related to weight, size, shape, operational safety, aerosol production rate, or electric or liquid capacity.

The formulation of the liquid 8 may vary depending on the intended purpose. Typically, the formulation of the liquid 8 can be adapted to provide different flavors to the generated aerosol 2. For the application in electronic cigarettes, for example, the main ingredients of the liquid 8 are typically propylene glycol, glycerin, which serve as the solvent, and may further include various flavorings and, most often, nicotine in liquid form. For example, flavorings may contain menthol, sugars, esters, and pyrazines. The formulation of the liquid may contain acid. The formulation of the liquid 8 may contain additives that increase the conductivity of the liquid 8. An example for such an additive is sodium chloride, NaCl, which is widely used for cold vaporizers and inhalators. Based on measurements of typical formulations of the liquid 8 for the use in electronic cigarettes, wherein the formulations comprise 18 mg/ml nicotine diluted with 10 volume percent of ultrapure water and mixed with acid, the conductivity of the liquid 8 may be 63 pS/cm, 199 pS/cm or 962 pS/cm for formulations without NaCl, with 10 mg/ml NaCl or with 50 mg/ml NaCl, respectively.

The liquid 8 may flow from the capsule body 7 to the vaporization chamber 3 via the liquid conduit 6. The liquid conduit 6 may be provided as one or more rigid or flexible tubes or as one or more holes provided in an enclosure of the vaporization chamber 3. For example, a sidewall of a bottom section of the vaporization chamber 3 may comprise a liquid inlet allowing the liquid 8 to flow into the vaporization chamber 3, as shown in Figs. 1A and IB. The liquid conduit 6 may be provided with a valve which can be opened or closed to allow or prevent the flow of liquid 8 to the vapori zation chamber 3 . The valve may be a one-way valve that only allows the liquid 8 to flow in the direction of the vapori zation chamber 3 . The liquid conduit 6 may be provided with a filter to prevent pollutants from entering the vapori zation chamber 3 .

The vapori zation chamber 3 houses the pair of electrodes 4a , 4b . The liquid 8 may flow into the vapori zation chamber 3 where it may be exposed to the electric de potential in the vapori zation volume 5 between the pair of electrodes 4a, 4b . The pair of electrodes 4a, 4b may be metal based electrodes , such as electrodes made from stainless steel , copper, nickel or gold .

In Fig . 3 , the pair of electrodes 4a, 4b is provided parallel to the flow direction of the l iquid 8 , such that the de electric potential is perpendicular to the flow direction . However, the pair of electrodes 4a, 4b may also be provided perpendicular to the flow direction of the liquid 8 , such that the de electric potential is ( approximately) parallel to the flow direction of the liquid 8 . In this case , the pair of electrodes 4a, 4b may be provided with holes or as a grating in order to allow the liquid 8 to enter, and the aerosol 2 to exit the vapori zation volume 5 . Such an embodiment will be exempli fied with reference to , for example , Figs . 5A and 5B .

The distance between the pair of electrodes 4a, 4b may be determined based on the required de electric potential to be applied and the electric power provided by the electronic vapor inhaler 17 in order to ensure that the liquid 8 is heated and vapori zed suf ficiently quick . The smaller the distance between the pair of electrodes 4a, 4b is , the larger the applied de electric potential is at a given output power level provided by the electronic vapor inhaler 17 , which may result in faster heating of the liquid 8 and thus in an increased amount of aerosol 2 generated . Hence , a lower distance between the pair of electrodes 4a, 4b may result in a better heating ef ficiency . The distance between the pair of electrodes 4a, 4b may be arranged using an insulating spacer . The distance between the pair of electrodes 4a, 4b may preferably be 1 mm or less , and more preferably be 0 . 5mm or less . Further, the distance between the pair of electrodes 4a, 4b may preferably be 0 . 5 mm or less , and more preferably be 1 mm or less . Especially the latter options may provide advantages in relation to manufacturing costs .

The vapori zation chamber 3 may be provided with a valve in the direction of the mouthpiece 14 . The valve can be opened or closed to allow or prevent the aerosol 2 from flowing into the vapor conduit 9 . This way, the discharge of aerosol 2 may be immediately disabled . The valve may be a one-way valve that only allows the aerosol 2 to flow toward the mouthpiece 14 .

Moreover, the vapori zation chamber 3 may be provided with one or more sediment traps that can hold a residue after heating . The sediments traps may serve as reservoirs in which particles suspended in the liquid 8 can accumulate . The type of residue depends on the formulation of the liquid 8 . A typical residue is , for example , tobacco . The sediment traps may be provided as recesses and may be arranged within the vapori zation chamber 3 in the direction of the liquid conduit 6 . The sediments traps may prevent residue from depositing within the vapori zation volume 5 where it may negatively af fect the ohmic heating process by partially shielding the de current flow . Such an embodiment will be exempli fied with reference to Fig . 5B . Within the vapori zation volume 5 , electric energy may be trans ferred directly to the liquid 8 . The de current flow may flow from one electrode 4a/b through the liquid 8 in the vapori zation volume 5 to the other electrode 4b/a, wherein the liquid 8 may be treated as a resistor . Heat may be generated rapidly and uni formly in the liquid 8 vapori zation volume 5 without any intermediate steps . The larger the amount of de current flow between the pair of electrodes 4a, 4b is , the larger the heating rate is . The amount of de current flow between the pair of electrodes 4a, 4b through the liquid 8 in the vapori zation volume 5 depends on the conductivity of the liquid 8 . The conductivity may depend on various factors such as the temperature of the liquid 8 and its composition, speci fically concentrations of ions and the type of ions .

When the liquid 8 in the vapori zation volume 5 is heated to its boiling temperature , aerosol 2 may be generated . The aerosol 2 may flow out of the vapori zation chamber 3 towards the mouthpiece 14 . The air flow 10 inside the vapor conduit 9 may transport the aerosol 2 out of the capsule 1 such that it may be inhaled by the user via the mouthpiece 14 . The air flow 10 may be generated by a vacuum generated by the user through sucking, by natural convection, with a fan or similar means of generating a pressure dif ference . The vapor conduit 9 may be provided with a valve which can be opened or closed to allow or prevent the air flow 10 through the vapor conduit 9 . The vapor conduit 9 may be provided with one or more filters to prevent pollutants such as dust or soot particles from entering and/or exiting the vapor conduit 9 .

Using a de power source provided by the electronic vapor inhaler 17 , the de potential is applied to the pair of electrodes 4a, 4b . The de current may be provided by a recti fied ac power source or, preferably, by a battery . The battery may, for example , be a single-use battery such as an alkaline battery or the like , or a rechargeable battery such as a lithium ion accumulator or the like .

The electronic vapor inhaler 17 may be provided with an interface , comprising, for example , an actuation element such as a button, a slider and/or a rotary knob, in order to allow the user to control an output power of the de power source . The interface may further be used to control one or more valves , to display a current level of the electric or liquid capacity or to ej ect the capsule 1 . The interface may further comprise a display, such as one or more indicator LEDs for indicating a status of the capsule 1 , an operation of the electronic vapor inhaler 17 , an electric and/or liquid capacity or the like .

Fig . 3 illustrates an embodiment in which the vapori zation chamber 3 is arranged below the current fill level of the liquid 8 so that the liquid 8 flows from the capsule body 7 into the vapori zation volume 3 . In other words , as long as the vapori zation volume 5 is located below a current fil l level of the liquid 8 within the capsule body 7 , liquid 8 can flow from the capsule body 7 through the liquid conduit 6 into the vapori zation volume 5 via gravity . In the example of Figs . 1A and IB, the vapori zation chamber 3 may be arranged at an inner bottom surface of the capsule body 7 such that the liquid 8 accommodated above the vapori zation chamber 3 flows into the vapori zation volume 5 .

Fig . 4 shows a schematic of an internal layout of a capsule 1 according to another embodiment in a cross-sectional view . Here , the capsule body 7 is , for the most part , located below the vapori zation volume 5 . The current fill level of the liquid 8 within the capsule body 7 may lie below the vapori zation volume 5 . However, the liquid conduit 6 and/or the vapori zation chamber 3 may be arranged as part of a capillary arranged to draw liquid 8 from the capsule body 7 into the vapori zation volume 5 . This way, the liquid 8 can flow from the capsule body 7 through the liquid conduit 6 into the vapori zation volume 5 via capillary action : I f a diameter of the capillary is suf ficiently small , then the combination of surface tension and adhesive forces between the liquid 8 and the wall of the capillary act to propel the liquid 8 . The capillary action can occur without the assistance of , or even in opposition to , external forces like gravity . Therefore , the capsule 1 according to this embodiment may operate more reliably in di f ferent orientations .

The capsule 1 of Fig . 4 may further comprise a mixing chamber 15 . The mixing chamber 15 may be arranged to temporarily accommodate the aerosol 2 before trans fer to the vapor conduit 9 . The mixing chamber 15 may be connected to the vapor conduit to allow mixture o f the aerosol 2 and air in vapor conduit 9 . In the mixing chamber 15 the aerosol 2 may cool down before it is inhaled by the user . The mixing chamber 15 may be provided with a transparent enclosure such that the user may observe the mixture of the aerosol 2 and air .

Figs . 5A and 5B illustrate a more compact design of the capsule 1 according to other embodiments , wherein the pair of electrodes 4a, 4b is provided perpendicular to the flow direction of the liquid 8 . Figs . 5A and 5B show a cross- sectional view of the capsule 1 which may have a cylindrical shape , wherein the arrow indicating the air flow 10 may coincide with the axis of symmetry . Hence , each electrode 4a/b may have the shape of a disc which is provided with a plurality of holes or as a grating in order to allow the liquid 8 to enter, and the aerosol 2 to exit the vapori zation volume 5 . The capsule body 7 may be arranged to surround the vapor conduit 9 and the vapori zation chamber 3 .

The capsule 1 shown in Fig . 5B i s provided with a sediment trap 12 that can hold a residue after heating . The sediment trap 12 may be provided such that it can be easily accesses from the outside in order to remove the residue . The sediment trap 12 may be provided may be provided in the vapori zation chamber 3 in the direction of the liquid conduit 6 . In other words , the sediment trap 12 may be provided below the vapori zation volume 5 to collect the residue after heating .

The vapori zation chamber 3 may be provided with a gauze 19 in the direction of the mouthpiece 14 . In other words , the gauze 19 may be arranged above the pair of electrodes 4a, 4b . The gauze 19 may allow the generated aerosol 2 to pass through but prevent any liquid 8 which has not yet been vapori zed from exiting the vapori zation volume 5 . This way, leakage o f the liquid 8 toward the mouthpiece 14 may be prevented, thereby ensuring that the user does not take in the liquid 8 directly .

As shown in Fig . 6 , in addition to a gauze 19 above the pair of electrodes 4a, 4b, leakage of the liquid 8 toward the mouthpiece 14 may further be prevented by providing a reces s structure inside the vapori zation chamber 3 and/or the vapor conduit 9 . The recess structure may be arranged to channel the air flow 10 such that intake air flows over the pair of electrodes 4a, 4b above which the recess structure is arranged to capture any unvapori zed liquid and guide it back toward the vapori zation volume 5 . The channeled air flow 10 may ef ficiently skim the aerosol 2 generated in the vapori zation volume 5 . This way, the vapor saturation of the air flow 10 may be increased . The air flow 10 may then be channeled such as to discharge only the generated aerosol 2 toward the mouthpiece 14, for example, via the vapor conduit 9.

Fig. 7 shows a plot of the conductivity of the liquid 8 with respect to the temperature of the liquid 8. The curve corresponds to a polynomial fit of second order to data points taken from the literature. The solid part of the curve represents the range described by the literature and the dotted part of the curve represent the extrapolation of the former. The conductivity is normalized to the value of conductivity of the liquid 8 at a temperature of 20°C of the liquid 8. As can be seen from Fig. 7, below around 25°C, the liquid 8 has a low conductivity which corresponds to a high resistance of the liquid 8.

In the following, several exemplary values of the resistance and conductivity of typical formulations of the liquid 8 for the use in electronic cigarettes are given, wherein it is assumed that the liquid 8 has a temperature of or below 25°C. One formulation comprising 12 mg/ml nicotine may have a conductivity of 5 pS/cm resulting in a resistance of 20 kQ or 10 kQ for electrodes having a distance of 1 mm or 0.5 mm, respectively. Another formulation comprising 18 mg/ml nicotine and mixed with benzoic acid may have a conductivity of 18 pS/cm resulting in a resistance of 5555 Q or 2778 Q for electrodes having a distance of 1 mm or 0.5 mm, respectively. When diluted with 10 (20) volume percent of ultrapure water, said formulation comprising 18 mg/ml nicotine and mixed with benzoic acid may have a conductivity of 68 (124) pS/cm resulting in a resistance of 1471 Q (806 Q) or 735 Q (403 Q) for electrodes having a distance of 1 mm or 0.5 mm, respectively .

Limitations in the construction of the capsule 1 and power requirements for generating the aerosol 2 lead to a conductive threshold below which ohmic heating may be used ef ficiently . The conductive threshold corresponds the maximal total resistance of the circuit used for heating . The amount of power generated by the electronic vapor inhaler 17 may be limited . On the other hand, the minimal amount of power required for nearly instantaneous vapori zation of the liquid 8 may be around 7 W . Furthermore , in order to ensure safe operations of the capsule 1 and the electronic vapor inhaler 17 , the input voltage should not be increased above a safe contact level of 60 V . Otherwise additional and costly measures such as additional insulation of contacts and wiring would be needed . The maximal total resistance is therefore ( 60 V) ² / 7 W = 514 Q which is an example for the conductive threshold .

This invention proposes pre-heating of the liquid 8 to signi ficantly improve the conductivity j ust at the early stage of the heating process . After a pre-heating temperature is reached, for example 50 ° C, ohmic heating may be dominating or even the only heating mechanism . This way, the resistance of the liquid 8 , which is heated to the pre-heating temperature , may be reduced below the conductive threshold, for example the maximal total resistance of 514 Q as described above . The liquid 8 having the pre-heating temperature may then be heated efficiently via ohmic heating to generate the aerosol 2 . The pre-heating temperature may be between 50 ° C and 100 ° C .

Figs . 8A and 8B show a section of the capsule 1 according to Fig . 3 , the section comprising the liquid conduit 6 and the vapori zation chamber 3 , including a pre-heating element 16 . As shown in Fig . 8A, the pre-heating element 16 may be arranged before the vapori zation volume 5 , for example , between the liquid conduit 6 and the vapori zation volume 5 . This way the liquid 8 flowing from the liquid conduit 8 into the vapori zation chamber 3 is pre-heated and at least a part of the liquid 8 entering the vapori zation volume 5 has the pre-heating temperature . Alternatively, as shown in Fig . 8B, the pre-heating element 16 may be arranged within the vapori zation volume 5 , that is between the pair of electrodes 4a, 4b . This way, at least part of the liquid 8 within the vapori zation volume 5 is heated to the pre-heating temperature .

It should be noted that , although not shown in the corresponding illustrations , the capsule 1 according to the embodiments shown in Figs . 4 , 5A, 5B and 6 also each comprise a pre-heating element which may be arranged before or within the vapori zation volume 5 as described above .

The pre-heating element 16 may be arranged between the pair of electrodes such that it is in electrical contact with the pair of electrodes 4a, 4b during pre-heating, and the electronic vapor inhaler 17 may be configured to apply power to the pre-heating element 16 via the pair of electrodes 4a, 4b . Furthermore , the power supplied to the pair of electrodes 4a, 4b may remain at a same voltage level during pre-heating and during continued heating of liquid 8 , having the preheating temperature , to the vapori zation temperature .

The capsule 1 may be configured to heat liquid to the preheating temperature in response to an activation signal . For example , activation signal may be triggered using the interface of the electronic vapor inhaler 17 described above .

Figs . 9A and 9B illustrate the pair of electrodes 4a, 4b according to the embodiment described with reference to Figs . 5A, 5B and 6 , wherein the pair of electrodes 4a, 4b are connected via the first set of contact I la to the de power source provided by the electronic vapor inhaler 17 and have the shape of a disc which is provided with a plurality of holes. Fig. 8A shows the pair of electrodes 4a, 4b from an angled point of view. The central hole may serve as a duct for the vapor conduit 9. The smaller holes in electrode 4b may allow liquid 8 to enter the vaporization volume 5. The smaller holes in electrode 4a may allow the aerosol 2, generated via ohmic heating, to exit the vaporization volume 5 in the direction of the vapor conduit 9. A gauze 19 may be provided above the electrode 4a to prevent leakage of the liquid 8 into the vapor conduit 9. Fig. 8B shows the pair of electrodes 4a, 4b from a side view. An insulating spacer 13 may be provided between the pair of electrodes 4, 4b in order to set a distance between the pair of electrodes 4a, 4b to a certain value. The insulating spacer 13 does not conduct the de current flow. In order to maximize the heating efficiency, the distance may preferably be 1 mm or less, and more preferably be 0.5mm or less. A gauze 19 may be provided above the upper electrode 4a to prevent leakage of unvaporized liquid 8.

Fig. 10 shows the pair of electrodes 4a, 4b from a side view according to the embodiment described with reference to Figs. 5A, 5B and 6. Here, the pre-heating element 16 may be provided by a Positive Temperature Coefficient (PTC) resistor 16-1, the resistance of which increases with its temperature. The PTC resistor 16-1 may be arranged within the vaporization volume 5, between the pair of electrodes 4a, 4b, and may be in direct contact with each of the pair of electrodes 4a, 4b such that the de current may flow through the PTC-resistor 16-1 from one electrode to the other. This way, heat may be generated within the PTC resistor 16-1 and the surrounding liquid 8 within the vaporization volume 5 may be heated to the pre-heating temperature. The PTC resistor 16-1 may be arranged in order to set a distance between the pair of electrodes 4a, 4b to a certain value. Fig . 9 shows a plot of the resistance of the PTC resistor 16- 1 with respect to the temperature . Hence , the conductive threshold may be associated with the pre-heating temperature below which resistive heating may be dominant and above which ohmic heating may be dominant . For example , at a temperature of 70 ° C, the PTC resistor 16- 1 may have a resistance below the conductive threshold . This way, the de current will primarily flow through the PTC resistor 16- 1 when the temperature of the liquid 8 in the vapori zation volume 5 is below the pre-heating temperature, thereby heating at least part of the liquid 8 to the pre-heating temperature via resistive heating . When the temperature of the liquid 8 in the vapori zation volume 5 i s above the pre-heating temperature , the de current will primarily flow through the liquid 8 between the pair of electrodes 4a, 4b, thereby further heating the pre-heated liquid 8 .

Fig . 12 shows a circuit diagram comprising a de power source provided by the electronic vapor inhaler 17 and a parallel circuit comprising the PTC resistor 16- 1 and a resistor given by a liquid 8 in a vapori zation volume 5 . The de power source provided by the electronic vapor inhaler 17 is connected via the first set of contacts I la to the pair of electrodes 4 , 4b, not shown in Fig . 12 . The de current flow may flow through the PTC resistor 16- 1 and the liquid 8 in the vapori zation volume 5 and said liquid 8 may be treated as a resistor .

The electronic vapor inhaler 17 may comprise a current regulator for controlling the de current flow between the two electrodes 4a, 4b and the liquid 8 in the vapori zation volume 5 on the basis of a target vapori zation power . The target vapori zation power may be based on the conductivity or resistance of the liquid 8, an output voltage of the de power supply 11, the distance between the pair of electrodes 4a, 4b and a desired amount of generated aerosol 2.

Fig. 13 shows plots of the expected resistance of the PTC resistor 16-1 and of the resistor given by the liquid 8 in the vaporization volume 5 with respect to the temperature of that liquid 8. The dotted curve shows the expected resistance of PTC resistor 16-1, the dashed curve shows the expected resistance of the liquid 8 in the vaporization volume 5 and the solid curve shows the resulting total resistance of the parallel circuit formed by the PTC resistor 16-1 and the liquid 8 in the vaporization volume 5. As shown in Fig. 13, by pre-heating the liquid 8 in the vaporization volume 5 to the pre-heating temperature, the total resistance may remain below the conductive threshold of, for example, 514 Q, as described above.

Figs. 14A and 14B show the pair of electrodes 4a, 4b from a side view according to the embodiment described with reference to Figs. 5A, 5B and 6. Here, the pre-heating element 16 may be provided by a bi-metallic strip 16-2 which is composed of two separate metal layers of different type joined together. The bi-metallic strip 16-2 may convert a temperature change into mechanical displacement. The bimetallic strip 16-2 may be arranged within the vaporization volume 5, between the pair of electrodes 4a, 4b, and one end of the bi-metallic strip 16-2 may be attached, e.g. welded, to one of the pair of electrodes 4a, 4b.

Below a certain temperature, which may be the pre-heating temperature, the bi-metallic strip 16-2 may be in contact which each of the pair of electrodes 4a, 4b such that the de current may flow through the bi-metallic strip 16-2 from one electrode to the other, as shown in Fig. 14A. This way, heat may be generated within the bi-metallic strip 16-2 and the surrounding liquid 8 within the vapori zation volume 5 may be heated to the pre-heating temperature .

Above the certain temperature , which may be the pre-heating temperature , the bi-metallic strip 16-2 may deform and loose contact with the one electrode to which it is not attached, as shown in Fig . 14B . Hence , the bi-metallic strip 16-2 may serve as a temperature-dependent switch such that the de current flow through the bi-metallic strip 16-2 is interrupted above the certain temperature and the liquid 8 in the vapori zation volume 5 is heated only via ohmic heating .

The current regulator provided by the electronic vapor inhaler 17 may further be configured to regulate a first voltage level to the pair of electrodes 4a, 4b during preheating and control a second voltage level to the pair of electrodes during continued heating of liquid having the preheating temperature , wherein the first voltage level is lower than the second voltage level .

The electronic vapor inhaler 17 may further be configured to measure a current through the pair of electrodes 4a, 4b, and switch the voltage from the first voltage level to the second voltage level when the measured current reaches a threshold level .

Fig . 15 shows plots of the temperature of the liquid 8 in the vapori zation volume 5 , the current through the bi-metallic strip 16-2 and the current through the liquid 8 in the vapori zation volume 5 with respect to time . As described above , when the bi-metallic strip 16-2 reaches the preheating temperature , the de current flows only through the liquid 8 in the vapori zation volume 5 , thereby heating the liquid 8 via ohmic heating . Figs . 16 , 17A and 17B shows the pair of electrodes 4a, 4b from a side view according to the embodiment described with reference to Figs . 5A, 5B and 6 . As shown in Fig . 16 , the pre-heating element 16 may be provided by a coil 16-3 in the vapori zation chamber 3 outside the vapori zation volume 5 . Figs . 16 and 17A show the pair of electrodes 4a, 4b from a side view according to the embodiment described with reference to Figs . 5A, 5B and 6 . Alternatively, as shown in Figs . 17A and 17B, the coil 16-3 may be arranged within the vapori zation volume 5 , that is in the space between the pair of electrodes 4a, 4b . The capsule 1 may comprise a second set of contacts 11b to supply power provided by the electronic vapor inhaler 17 to the coil 16- 3 . This way, the coil 16- 3 and at least a part of the volume of the liquid 8 surrounding the coil 16-3 is heated to the pre-heating temperature in accordance with the power delivered to coil 16-3 .

A coil 16-3 arranged within the vapori zation volume 5 may be provided with electrical insulation and arranged in order to set a distance between the pair of electrodes 4a, 4b to a certain value .

The electronic vapor inhaler 17 may further be configured to measure a resistance of the liquid 8 in the vapori zation volume 5 and stop the supply of power to the coil 16-3 when the measured resistance of the liquid 8 in the vapori zation volume 5 is smaller than the conductive threshold .

Fig . 16 shows plots of the temperature of the liquid 8 in the vapori zation volume 5 , the electric power through the coi l 16-3 and the electric power through the liquid 8 in the vapori zation volume 5 with respect to time . As described above , when the resistance of the liquid 8 in vapori zation volume 5 becomes smaller than the conductive threshold, the supply of power to the coil 16-3 is stopped and the de current flows only through the liquid 8 in the vapori zation volume 5 , thereby heating the liquid 8 in the vapori zation volume 3 via ohmic heating .

It should be noted that , although the working principle and ef fects of a PTC heater 16- 1 , a bi-metallic strip 16-2 and a coil 16-3 serving as the pre-heating element 16 have been exempli fied in view of to the embodiments described with reference to Figs . 5A, 5B and 6 , the implementation of such pre-heating elements 16 is not limited thereto . A PTC heater 16- 1 , a bi-metallic strip 16-2 or a coil 16-3 serving as the pre-heating element 16 may be arranged in any other embodiment of the capsule 1 , for example , any one of the embodiments described with reference to Figs . 3 or 4 .

[Reference Signs ]

1 capsule

2 aerosol

3 vapori zation chamber

4a, 4b pair of electrodes

5 vapori zation volume

6 liquid conduit

7 capsule body

8 liquid

9 vapor conduit

10 air flow

I la first set of contacts

11b second set of contacts

12 sediment trap

13 insulating spacer

14 mouthpiece

15 mixing chamber

16 pre-heating element 16- 1 PTC resistor

16-2 bi-metallic strip

16-3 coil

17 electronic vapor inhaler 18 air inlet

19 gauze

Claims

Claims :

1. A capsule for use with an electronic vapor inhaler, the capsule comprising: a capsule body accommodating a liquid to be vaporized by heating; a vaporization chamber releasing vaporized liquid toward a mouthpiece; a pair of electrodes arranged in the vaporization chamber for leading a de current through a volume of the liquid in a space between the electrodes; and a pre-heating element for heating the liquid to a preheating temperature in at least a part of the volume of the liquid.

2. The capsule according to claim 1, further comprising a first set of contacts for applying power provided by the electronic vapor inhaler to the pair of electrodes.

3. The capsule according to any one of the preceding claims, wherein the vaporization chamber is arranged such that it receives the liquid through a liquid conduit, receives intake air from an air inlet, and releases vaporized liquid through a vapor conduit toward the mouthpiece.

4. The capsule according to any one of the preceding claims, wherein the vaporization chamber further comprises a mixing chamber arranged for mixing vaporized liquid with intake air.

5. The capsule according to any one of the preceding claims, wherein the vaporization chamber is part of a capillary arranged to draw the liquid from the capsule body into the space between the pair of electrodes. The capsule according to any one of claims 1 to 4 , wherein the vapori zation chamber is arranged at an inner bottom surface of the capsule body such that the liquid accommodated above the vapori zation chamber flows into the space between the pair of electrodes . The capsule according to any one o f the preceding claims , wherein the pair of electrodes are disc-shaped, and each comprise a plurality of holes . The capsule according to any one o f the preceding claims , further comprising a gauze above the pair of electrodes to prevent leakage of the liquid toward the mouthpiece . The capsule according to any one o f the preceding claims , wherein a distance between the pair of electrodes is 1mm or less , and preferably 0 . 5mm or less . The capsule according to any one o f the preceding claims , further comprising a sediment trap below the space between the electrodes to collect a residue after heating . The capsule according to any one of the preceding claims , wherein the pre-heating element is arranged between the pair of electrodes such that it is in electrical contact with the pair of electrodes during pre-heating such that the de current is flowing through the pre-heating element . The capsule according to claim 11 , wherein the preheating element is a PTC resistor .

13 . The capsule according to claim 11 , wherein the preheating element is a bimetallic strip .

14 . The capsule according to any one of claims 1 to 10 , wherein the pre-heating element is a coil , and the capsule further comprises a second set of contacts for applying power provided by the electronic vapor inhaler to the coil . 15 . An electronic vapor inhaler arranged to connect with a capsule according to any one of the preceding claims .