WO2023242085A1

WO2023242085A1 - Pre-heating liquid in wickless vaporization arrangement

Info

Publication number: WO2023242085A1
Application number: PCT/EP2023/065595
Authority: WO
Inventors: Grzegorz Aleksander PILATOWICZ; Peter LOVEDAY
Original assignee: Jt International Sa
Priority date: 2022-06-13
Filing date: 2023-06-12
Publication date: 2023-12-21

Abstract

A vaporization arrangement for an inhaler and configured to generate an aerosol to be inhaled by a user comprising a vaporization chamber comprising a pair of electrodes defining a vaporization volume between the pair of electrodes; a pre-heating element arranged to heat at least a part of liquid in said vaporization volume to a pre-heating temperature; and a dc power source arranged to apply an electric dc potential to the pair of electrodes to generate a dc current flow between the two electrodes and liquid in the vaporization volume having the pre-heating temperature.

Description

Pre-heating liquid in wickless vaporization arrangement

[ Technical Field]

The present invention relates to an aerosol generation unit . 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 vapori zation arrangement proposed in the present disclosure is based on the ohmic heating principle . Ohmic heating means that an electric current flows directly through a liquid in a vapori zation volume . 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 vapori zation arrangement does not require any wicking material . I f there is no liquid in the vapori zation volume , 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 o f 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 vapori zation arrangement 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 vapori zation arrangements 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 vapori zation arrangement may be limited . When the safe contact voltage level i s 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 vapori zation arrangement for an inhaler and configured to generate an aerosol to be inhaled by a user comprising a vapori zation chamber comprising a pair of electrodes defining a vapori zation volume between the pair of electrodes ; a pre-heating element arranged to heat at least a part of liquid in said vapori zation volume to a preheating temperature ; and a de power source arranged to apply an electric de potential to the pair of electrodes to generate a de current flow between the two electrodes and liquid in the vapori zation volume having the pre-heating temperature .

[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 . 1 shows a vapori zation arrangement according to an embodiment of the present invention wherein the pre-heating element is omitted;

Fig . 2A shows a vapori zation arrangement with a compact design according to an embodiment of the present invention wherein the preheating element is omitted;

Fig . 2B shows a vapori zation arrangement 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 . 3 shows a vapori zation arrangement 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;

Fig . 4 shows a vapori zation arrangement according to an embodiment of the present invention wherein the pre-heating element is omitted;

Fig . 5 shows a plot of the conductivity of the liquid with respect to the temperature of the liquid;

Fig . 6A shows a section of the vapori zation arrangement according to Fig . 1 , the section comprising the liquid conduit and the vapori zation chamber, including a preheating element ;

Fig . 6B shows a section of the vapori zation arrangement according to Fig . 1 , the section comprising the liquid conduit and the vapori zation chamber, including a preheating element ;

Fig . 7A shows from an angled point of view a pair of electrodes according to an embodiment of the present invention;

Fig . 7B shows from a side view a pair of electrodes according to an embodiment of the present invention;

Fig . 8 shows from a side view a pair of electrodes with a PTC resistor in between according to an embodiment of the present invention; Fig . 9 shows a plot of the resistance of the PTC resistor with respect to its temperature ;

Fig . 10 shows a circuit diagram compri sing a de power source , a current regulator and a parallel circuit comprising the PTC resistor and a resistor given by a liquid in a vapori zation volume ;

Fig . 11 shows plots of the expected res istance of the PTC resistor and of the resistor given by the liquid in the vapori zation volume with respect to the temperature of that liquid;

Fig . 12A 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 . 12B 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 . 13 shows plots of the temperature of the liquid, the current through the bi-metallic strip and the current through the liquid in the vapori zation volume with respect to time ;

Fig . 14 shows a flowchart representing the control logic of a vapori zation arrangement with a bi-metallic strip as the pre-heating element according to an embodiment of the present invention;

Fig . 15 shows from a side view a pair of electrodes with a coil outside the vapori zation volume according to an embodiment of the present invention;

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

Fig . 16B 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;

Fig . 17 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 ; and

Fig . 18 shows a flowchart representing the control logic of a vapori zation arrangement with a coil as the pre-heating element according to an embodiment of the present invention .

[ 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. 1 shows a vaporization arrangement 1 according to an embodiment of the invention in a cross-sectional view. The vaporization arrangement 1 is configured to generate an aerosol 2 to be inhaled by a user. The vaporization arrangement 1 comprises a vaporization chamber 3 comprising a pair of electrodes 4a, 4b. The pair of electrodes 4a, 4b define a vaporization volume 5 between them. A liquid 8 is supplied to the vaporization chamber 3. A de power source 11, not shown in Fig. 1, is arranged to apply an electric de potential to 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. A de current flow is generated between the pair of electrodes 4a, 4b and passes through the liquid 8 in the vaporization volume 5. This way, the liquid 8 can be heated via ohmic heating to its boiling temperature to generate the aerosol 2. The vaporization arrangement 1 further comprises a pre-heating element 16, not shown in Fig. 1, which is arranged to heat at least a part of the liquid in the vaporization volume 5 to a pre-heating temperature. The arrangement of the pre-heating element 16 within the vaporization arrangement 1 will be described with reference to Figs. 6A and 6B .

A liquid conduit 6 may be arranged to supply, from a liquid store 7, the liquid 8 to the vaporization chamber 3. A vapor conduit 9 may be arranged to discharge the aerosol 2, generated in the vaporization volume 5, from the vaporization chamber 3. The air flow 10, indicated by the arrow in Fig. 1, illustrates the direction in which the aerosol 2 may be discharged to then be inhaled by a user.

The vaporization arrangement 1 may be provided in an electronic cigarette, an electronic air freshener or a medical inhaler. Depending on the application, the vaporization arrangement 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 store 7 may serve as a reservoir for the liquid 8. The liquid store 7 may be provided as an exchangeable capsule or pod, which a user can insert into the vapori zation arrangement 1 in detachable manner . For example , the user can attach a capsule to the vapori zation arrangement 1 such that the liquid 8 therein can flow from it , through the liquid conduit 6 and into the vapori zation chamber 3 . Then, when the liquid 8 in the capsule is depleted, that is most of the liquid 8 therein has been vapori zed, the user may detach the depleted capsule in order to insert a new one . The liquid store 7 may be connected to a secondary reservoir, not shown in Fig . 1 , which may serve as the exchangeable capsule or pod in this case . The liquid store 7 may be provided with a transparent enclosure such that the user may observe the fill level of the liquid 8 .

The liquid conduit 6 may connect the liquid store 7 with the vapori zation chamber 3 such that the liquid 8 can flow from the liquid store 7 to the vapori zation chamber 3 . 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 vapori zation chamber 3 . For example , a sidewall of a bottom section of the vapori zation chamber 3 may comprise a liquid inlet allowing the liquid 8 to flow into the vapori zation chamber 3 . For an exchangeable liquid store 7 the liquid conduit 6 may be provided with sealings , such as gaskets , that prevent leakage of the liquid 8 . 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 . 1 , the pair of electrodes 4a, 4b is provided parallel to the flow direction of liquid 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 Figs . 2A and 2B and Figs . 3A and 3B .

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 de power source 11 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 of the de power source 11 , which may result in faster heating of the liquid 8 and thus in an increased amount o f 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 gauze 18 in the direction of the vapor conduit 9 . In other words , the gauze 18 may be arranged above the pair of electrodes 4a, 4b . The gauze 18 may allow the generated aerosol 2 to pass through but prevent any liquid 8 which has not yet been vapori zed from exiting the vaporization volume 5 . This way, leakage of the liquid 8 into the vapor conduit 9 may be prevented, thereby ensuring that the user does not take in the liquid 8 directly .

Furthermore , the vapori zation chamber 3 may be provided with a valve in the direction of the vapor conduit 9 . 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 in the direction of the vapor conduit 9 .

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 . 2B . 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 vapor conduit 9 . The air flow 10 inside the vapor conduit 9 may transport the aerosol 2 out of the vapori zation arrangement 1 such that it may be inhaled by the user . 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 di f 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 .

The de power source 11 applies the electric de potential to the pair of electrodes 4a, 4b . The de power source 11 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 vapori zation arrangement 1 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 11 . 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 liquid store 7 or any capsule or pod used to store the liquid 8 . The interface may further comprise a display, such as one or more indicator LEDs for indicating an operation of the vapori zation arrangement 1 , an electric and/or liquid capacity or the like .

Figs . 2A and 2B illustrate a more compact design of the vapori zation arrangement 1 according to other embodiments , wherein the pair of electrodes 4a, 4b is provided perpendicular to the flow direction of the liquid 8 . Figs . 2A and 2B show a cross-sectional view of the vapori zation arrangement 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 liquid store 7 may be arranged to surround the vapor conduit 9 and the vapori zation chamber 3 . The liquid store 7 may be connected to a secondary reservoir, not shown in Figs . 2A and 2B, such as an exchangeable capsule or pod . The vapori zation arrangement 1 shown in Fig . 2B is 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 .

As shown in Fig . 3 , in addition to a gauze 18 above the pair of electrodes 4a, 4b, leakage of the liquid 8 toward the vapor conduit 9 may further be prevented by providing a recess 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 vapor conduit 9 .

Figs . 1 , 2A and 2B illustrate embodiments in which the vapori zation chamber 3 is arranged below the fill level of the liquid in the liquid store 7 so that the liquid 8 flows from the liquid store 7 into the vapori zation volume 3 . In other words , as long as the vapori zation volume 5 is located below a current fill level of the liquid 8 within the liquid store 7 , liquid 8 can flow from the liquid store 7 through the liquid conduit 6 into the vapori zation volume 5 via gravity . Fig . 4 shows the vapori zation arrangement 1 in another embodiment in a cross-sectional view . Here , the liquid store 7 is , for the most part , located below the vapori zation volume 5 . The current fill level of the liquid 8 within the liquid store 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 liquid store 7 into the vapori zation volume 5 . This way, the liquid 8 can flow from the liquid store 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 vapori zation arrangement according to this embodiment may operate more reliably in di f ferent orientations .

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

Fig . 5 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. 5, 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 vaporization arrangement 1 and power requirements for generating the aerosol 2 lead to a conductive threshold below which ohmic heating may be used efficiently. The conductive threshold corresponds the maximal total resistance of the circuit used for heating. The amount of power generated by the de power source 11 may be limited. On the other hand, the minimal amount of power required for nearly instantaneous vaporization of the liquid 8 may be around 7 W. Furthermore, in order to ensure safe operations of the vaporization arrangement 1, 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 significantly improve the conductivity just 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. 6A and 6B show a section of the vaporization arrangement 1 according to Fig. 1, the section comprising the liquid conduit 6 and the vaporization chamber 3, including a pre-heating element 16. As shown in Fig. 6A, the pre-heating element 16 may be arranged before the vaporization volume 5, that is between the liquid conduit 6 and the vaporization volume 5. This way the liquid 8 flowing from the liquid conduit 8 into the vaporization chamber 3 is pre-heated and at least a part of the liquid 8 entering the vaporization volume 5 has the pre-heating temperature. Alternatively, as shown in Fig. 6B, the pre-heating element 16 may be arranged within the vaporization volume 5, that is between the pair of electrodes 4a, 4b. This way, at least part of the liquid 8 within the vaporization volume 5 is heated to the pre-heating temperature . It should be noted that , although not shown in the corresponding illustrations , the vapori zation arrangements 1 according to the embodiments shown in Figs . 2A, 2B and 3 also each comprise a pre-heating element which may be arranged before or within the vapor i zation volume 5 as described above .

The pre-heating element 16 may be in contact with the pair of electrodes 4a, 4b during pre-heating, and the de power source 11 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 pre-heating temperature , to the vapori zation temperature .

The vapori zation arrangement 1 may be configured to heat liquid to the pre-heating temperature in response to an activation signal . For example , activation signal may be triggered using the interface described above .

Figs . 7A and 7B illustrate the pair of electrodes 4a, 4b according to the embodiment described with reference to Figs . 2A and 2B, wherein the pair of electrodes 4a, 4b are connected to the de power source 11 and have the shape of a disc which is provided with a plurality of holes . Fig . 7A shows the pair of electrodes 4a, 4b from an angled point o f 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 vapori zation volume 5 . The smaller holes in electrode 4a may allow the aerosol 2 , generated via ohmic heating, to exit the vapori zation volume 5 in the direction of the vapor conduit 9 . A gauze 18 may be provided above the electrode 4a to prevent leakage of the liquid 8 into the vapor conduit 9 . Fig . 7B 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.

Fig. 8 shows the pair of electrodes 4a, 4b from a side view according to the embodiment described with reference to Figs. 2A and 2B. 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 vaporization 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 vaporization volume 5 is 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.

The vaporization arrangement 1 according to the embodiment described with reference to Fig. 8 may optionally be provided with a current regulator 14, as shown schematically in the circuit diagram of Fig. 10. The de power source 11 is connected via the current regulator 14 to the pair of electrodes 4, 4b, not shown in Fig. 10. The de current flow may flow through the PTC resistor 16-1 and the liquid 8 in the vaporization volume 5 and said liquid 8 may be treated as a resistor.

The current regulator 14 may control the de current flow between the two electrodes 4a, 4b and the liquid 8 in the vaporization volume 5 on the basis of a target vaporization power. The target vaporization 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. 11 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. 11, 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 o f , for example , 514 Q, as described above .

Figs . 12A and 12B show the pair of electrodes 4a, 4b from a side view according to the embodiment described with reference to Figs . 2A and 2B . 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 di f ferent type j oined 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 vapori zation 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 . 12A. 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 . 12B . 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 de power source 11 may further be configured to regulate a first voltage level to the pair of electrodes 4a, 4b during pre-heating 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 de power source 11 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 . 13 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 .

Fig . 14 shows a flowchart representing the control logic of a vapori zation arrangement 1 with a bi-metallic strip 16-2 as the pre-heating element 16 according to an embodiment of the present invention .

In step S 10 , the conductive threshold of the liquid i s determined, and a previous resistance value is set to zero .

In step S20 , a current resistance of the liquid 8 in the vapori zation volume 5 is determined by measuring de current flow at maximum applied voltage . The de power source 11 may be arranged to measure the de current flow .

In step S30 , is determined whether or not the previous resistance value is equal to zero . If the previous resistance value is not equal to zero (NO in step S30) , it is determined whether or not the previous resistance value is larger than the current resistance.

If the previous resistance value is not larger than the current resistance (NO in step S80) , the heating process is stopped in step S90. It may further be determined that the vaporization arrangement 1 is malfunctioning since the resistance of the liquid 8 should decrease with increasing temperature .

If the previous resistance value is larger than the current resistance (YES in step S80) , the control logic continues with step S40.

If the previous resistance value is equal to zero (YES in step S30 or step S80) , it is determined, in step S40, whether or not the de current is flowing through the bi-metallic strip 16-2.

If the de current is flowing through the bi-metallic strip 16-2 (YES in step S40) , the voltage on the bi-metallic strip 16-2 is controlled, in step S70, so that the output power corresponds to a predetermined amount of power. The predetermined amount of power may be 7 W. The control logic then continues with step S60.

If the de current is not flowing through the bi-metallic strip 16-2 (NO in step S40) , maximum voltage is applied, in step S50, to the pair of electrodes 4a, 4b and then the voltage is adjusted to supply the pair of electrodes 4a, 4b with the predetermined amount of power for a predetermined time period. The predetermined time period may be 10 ms. The control logic then continues with step S60. In step S 60 , the current resistance is set as the previous resistance value . The control logic then continues with step S20 .

Figs . 15 , 16A and 16B shows the pair of electrodes 4a, 4b from a side view according to the embodiment described with reference to Figs . 2A and 2B . As shown in Fig . 15 , the preheating element 16 may be provided by a coil 16-3 in the vapori zation chamber 3 outside the vapori zation volume 5 . Figs . 16A and 16B show the pair of electrodes 4a, 4b from a side view according to the embodiment described with reference to Figs . 2A and 2B . Alternatively, as shown in Figs . 16A and 16B, the coil 16-3 may be arranged within the vapori zation volume 5 , that is between the pair of electrodes 4a, 4b . The de power source 11 may comprise a first module 17a to control power to the coil 16-3 and a second module 17b to control power to the pair of electrodes 4a, 4b . This way, heat may be generated within the coil 16-3 and the surrounding liquid 8 within, or flowing into , the vapori zation volume 5 may be heated to the pre-heating temperature in accordance with the power delivered to coi l 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 de power source 11 may 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. 17 shows plots of the temperature of the liquid 8 in the vaporization volume 5, the electric power through the coil 16-3 and the electric power through the liquid 8 in the vaporization volume 5 with respect to time. As described above, when the resistance of the liquid 8 in vaporization 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 vaporization volume 5, thereby heating the liquid 8 in the vaporization volume 3 via ohmic heating.

Similar to the control logic described with reference to Fig. 14 for the embodiment with a bi-metallic strip 16-2 as the pre-heating element 16, Fig. 18 shows a flowchart representing the control logic of a vaporization arrangement 1 with a coil 16-3 as the pre-heating element 16 according to an embodiment of the present invention. In the following, the description of steps identical to those already described with reference to Fig. 14 is omitted.

If the previous resistance value is equal to zero (YES in step S30 or step S80) , it is determined, in step S41, whether or not the current resistance is larger than the conductive threshold .

If the current resistance is larger than the conductive threshold (YES in step S41) , the coil 16-3 is supplied, in step S71, with a predetermined amount of power for a predetermined time period. The predetermined amount of power may be 7 W. The predetermined time period may be 10 ms. The control logic then continues with step S60.

If the current resistance is not larger than the conductive threshold (NO in step S41) , the control logic then continues with step S50. It should be noted that , although the working principle and ef fects of a PTC resistor 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 embodiment described with reference to Figs . 2A and 2B, the implementation of such preheating elements 16 is not limited thereto . A PTC resistor 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 vapori zation arrangement 1 , for example , any one of the embodiments described with reference to Figs . 1 or 3 .

[Reference Signs ]

1 vapori zation arrangement

2 aerosol

3 vapori zation chamber

4a, 4b pair of electrodes

5 vapori zation volume

6 liquid conduit

7 liquid store

8 liquid

9 vapor conduit

10 air flow

11 de power source

12 sediment trap

13 insulating spacer

14 current regulator

15 expansion chamber

16 pre-heating element

16- 1 PTC resistor

16-2 bi-metallic strip

16-3 coil

17a first module 17b second module

18 gauze

Claims

Claims :

1 . A vapori zation arrangement for an inhaler and configured to generate an aerosol to be inhaled by a user comprising : a vapori zation chamber comprising a pair of electrodes defining a vapori zation volume between the pair of electrodes ; a pre-heating element arranged to heat at least a part of liquid in said vapori zation volume to a pre-heating temperature ; and a de power source arranged to apply an electric de potential to the pair of electrodes to generate a de current flow between the two electrodes and liquid in the vapori zation volume having the pre-heating temperature .

2 . The vapori zation arrangement according to claim 1 , wherein the pre-heating element is arranged in the vapori zation volume .

3 . The vapori zation arrangement according to claim 2 , wherein the pre-heating element is in contact with the pair of electrodes during pre-heating, and the de power source is configured to apply power to the pre-heating element via the pair of electrodes .

4 . The vapori zation arrangement according to claim 3 , wherein the pre-heating element is a PTC resistor .

5 . The vapori zation arrangement according to claim 4 , wherein the power supplied to the pair of electrodes remains at a same voltage level during pre-heating and during continued heating of liquid having the preheating temperature to the vapori zation temperature .

The vapori zation arrangement according to claim 3 , wherein the pre-heating element is a bimetallic strip .

The vapori zation arrangement according to claim 6 , wherein the de power source is further configured to regulate a first voltage level to the pair of electrodes during pre-heating and control a second voltage level to the pair of electrodes during continued heating of liquid having the pre-heating temperature , wherein the first voltage level is lower than the second voltage level .

The vapori zation arrangement according to claim 7 , wherein the de power source is further configured to measure a current through the pair of electrodes , and switch the voltage from the first voltage level to the second voltage level when the measured current reaches a threshold level .

The vapori zation arrangement according to claim 2 , wherein the pre-heating element is a coil , the de power source comprises a first module to control power to the coil and a second module to control power to the pair o f electrodes .

The vapori zation arrangement according to claim 9 , wherein the de power source is further configured to : measure a resistance of liquid in the vapori zation volume ; and stop power to the coil when the measured resistance of liquid in the vaporization volume is smaller than a conductive threshold.

11. The vaporization arrangement according to any of the preceding claims, wherein the pre-heating temperature is between 50°C and 100°C.

12. The vaporization arrangement according to any of the preceding claims, wherein the vaporization arrangement is configured to heat liquid to the pre-heating temperature in response to an activation signal.