Aerosol Generation Device with Reduced Spitting Effect

An aerosol generation device includes a reservoir storing an aerosol-forming liquid having first and second mixed compounds having first and second boiling points, a heater for vaporizing the aerosol-forming liquid mixed with air in an aerosol chamber to generate an aerosol, a power source storing electrical energy, and a controller arranged, during each inhalation phase of a vaping session, for controlling supply of electrical power to the heater according to a chosen profile in which the electrical power varies over time depending on the first and second boiling points in order to control a vaporization ratio of the first and second compounds in the aerosol chamber.

FIELD OF THE INVENTION

The present invention relates to aerosol generation devices, and more precisely to the control of the composition of the aerosols that are generated by such aerosol generation devices during vaping sessions.

BACKGROUND

The invention concerns the aerosol generation devices often named “E-vapor devices” and comprising:

a reservoir storing an aerosol-forming liquid comprising at least first and second mixed compounds having respectively first and second boiling points,
a heater for vaporizing the aerosol-forming liquid mixed with air in an aerosol chamber to generate an aerosol,
a power source, possibly a rechargeable battery, storing electrical energy, and
a controller (or control device) arranged for controlling the supply of electrical power to the heater during each inhalation phase (or puff) of a vaping session.

Some aerosol-forming liquids comprises at least first and second mixed compounds having respectively first and second boiling points. This is notably the case for those comprising Propylene Glycol (PG) and Vegetable Glycerin/Glycerol (VG) with different ratios. It is recalled that propylene glycol has a first boiling point between 185° C. and 189° C., while vegetable glycerin/glycerol has a second boiling point around 290° C.

When the coil of the heater heats the compounds (or components) of the aerosol-forming liquid, these compounds can dissociate and the liquid with the lower boiling point can vaporise at a faster rate, which causes a build up of the component with the higher boiling point. A first part of the aerosol-forming liquid (or “e-liquid”) with the highest concentration of first compound (for instance PG) is located in the center of the heating area (generally a wick) surrounded by the heating element(s) of the heater, while a second part of the aerosol-forming liquid with the highest concentration of second compound (for instance VG) is located at the periphery of the heating area near the heating element(s). When some new aerosol-forming liquid is introduced into the heating area, the first compound (PG) newly introduced is heated above its first boiling point due to latent heat in the areas comprising a high concentration of hot and vaporized second compound (VG) and also due to the role of the heat capacity (i.e. if the VG build up is too much the temperature at the coil goes above the boiling point of PG, as does the VG rich area of the wick—this is what allows vaporisation of PG at the centre of the wick and thus bubbles of vapor forcing their way out from the centre and taking hot second compound rich liquid droplets with them, with symptoms such as cracks, pops, crackles). So, unwanted droplets of e-liquid that have not been completely vaporized reach the lips and/or mouth of the user during a puff, which may be unpleasant and therefore has a negative impact on the user experience. The generation of these unwanted e-liquid droplets is sometimes call “spitting effect”. Since this spitting effect has a randomised occurrence it causes variability of aerosol delivery.

To reduce the spitting effect it has been proposed to modify the heating area and/or the heater characteristics. For instance, it is possible to reduce the wick thickness inside the heater and/or to replace the wound coil of the heater with ceramic. But this induces a cost increase. It has been also proposed to place filter(s) and/or baffle(s) in the aerosol path to capture the generated e-liquid droplets (of the spitting effect). But this induces not only a cost increase, but also an increasing complexity of the internal architecture.

Therefore, an object of this invention is to improve the situation, and notably to allow decreasing the spitting effect without inducing a noticeable cost increase or an increasing complexity of the internal architecture.

SUMMARY OF THE INVENTION

The proposed invention provides notably an embodiment of an aerosol generation device comprising:

a reservoir storing an aerosol-forming liquid comprising at least first and second mixed compounds having respectively first and second boiling points,
a heater for vaporizing the aerosol-forming liquid mixed with air in an aerosol chamber to generate an aerosol,
a power source storing electrical energy, and
a controller arranged for controlling supply of electrical power to the heater during each inhalation phase of a vaping session.

This aerosol generation device is characterized in that its controller is arranged for controlling this supply according to a chosen profile in which the electrical power varies over time depending on the first and second boiling points in order to control a vaporization ratio of the first and second compounds in the aerosol chamber.

Thanks to the invention, the control of the level of the electrical power and of the duration at such a level allows to control the vaporization ratio of the first and second compounds, and therefore the ratio of vapor bubbles (rich of first compound) over unvaporized liquid droplets (rich of second compound) in the heating area, which allows reducing the spitting effect.

The embodiment of an aerosol generation device may comprise other aspects or features, considered separately or combined, as defined hereafter:the controller may be arranged for controlling the supply according to a chosen profile that allows minimizing the vaporization ratio of the first and second compounds in the aerosol chamber;in a first example of embodiment the controller may be arranged for controlling the supply according to a chosen profile comprising a first phase having a first duration at a first electrical power, a second phase having a second duration at a second electrical power greater than this first electrical power, and a third phase having a third duration at a third electrical power greater than this second electrical power;in this first example of embodiment the first, second and third durations may be equal to a chosen first value. For instance, this chosen first value may be comprised between 150 ms and 250 ms;in a second example of embodiment the controller may be arranged for controlling the supply according to a chosen profile comprising a first phase having a first duration at a first electrical power, a second phase having a second duration at an electrical power equal to zero, a third phase having a third duration at this first electrical power, a fourth phase having a fourth duration at an electrical power equal to zero, and a fifth phase having a fifth duration at this first electrical power;in this second example of embodiment the first, third and fifth durations may be equal to a chosen second value. For instance, this chosen second value may be comprised between 70 ms and 130 ms;also in this second example of embodiment the second and fourth durations may be equal to a chosen third value. For instance, this chosen third value may be comprised between 10 ms and 50 ms;in a third example of embodiment the controller may be arranged for controlling the supply according to a chosen profile comprising a phase having a chosen duration during which the electrical power strictly increases;in this third example of embodiment the controller may be arranged for controlling the supply according to a chosen profile comprising a phase during which the electrical power varies as a logarithmic function;also in this third example of embodiment the chosen duration may be comprised between 550 ms and 650 ms;the power source may be a rechargeable battery;the aerosol generation device may constitute an electronic cigarette (or e-cigarette).

The proposed invention provides also an embodiment of a method intended for controlling aerosol generation by an aerosol generation device comprising:

a reservoir storing an aerosol-forming liquid comprising at least first and second mixed compounds having respectively first and second boiling points,
a heater for vaporizing this aerosol-forming liquid mixed with air in an aerosol chamber to generate an aerosol,
a power source storing electrical energy, and
a controller arranged for controlling supply of electrical power to the heater during each inhalation phase of a vaping session.

This method is characterized in that it comprises a step in which the controller controls the supply according to a chosen profile in which the electrical power varies over time depending on the first and second boiling points in order to control a vaporization ratio of the first and second compounds in the aerosol chamber.

DETAILED DESCRIPTION OF EMBODIMENTS

The invention aims, notably, at proposing an aerosol generation device (or E-vapor device)1, comprising a cartomizer2(comprising an aerosol-forming liquid comprising at least first and second mixed compounds having respectively first bp1and second bp2boiling points) and an electrical and control device3, and subjected to a reduced spitting effect.

In the following description it will be considered that the aerosol generation device1is an electronic cigarette (or e-cigarette or else personal vaporizer). But an aerosol generation device1according to the invention could be of another type, as soon as it allows the generation of an aerosol by heating an aerosol-forming liquid (or e-liquid). So, for instance, the aerosol generation device1could be an inhaler.

Moreover, in the following description it will be considered that the aerosol-forming liquid comprises at least propylene glycol (or PG—first compound with a first boiling point bp1between 185° C. and 189° C.) and vegetable glycerin/glycerol (or VG—second compound with a second boiling point bp2around 290° C.). But the aerosol-forming liquid may comprise one or more of nicotinoid(s), cannabinoid(s), caffeine, tobacco material, organic acids, salts, flavoring, and combinations thereof, and a carrier (e.g. a liquid solvent) which may include propylene glycol, glycerin/glycerol, trimethylene glycol, water, ethanol, and combinations thereof.

Furthermore, in the following description the term “aerosol” may include a suspension of substance as one or more of solid particles, liquid droplets and gas. Such a suspension may be in a gas including air.

As illustrated partially inFIGS.1and2, an aerosol generation device1, according to the invention, comprises at least a reservoir5, a heater18, an aerosol chamber7, a power source23and a controller27.

For instance, and as illustrated in the non-limiting example ofFIGS.1and2, the reservoir5, the heater18and the aerosol chamber7may be part of a cartomizer2(possibly exchangeable and illustrated inFIG.1), while the power source23and the controller27may be part of an electrical and control device3(illustrated inFIG.2). In this embodiment, the electrical and control device3and the cartomizer2are intended to be physically and electrically coupled together.

As illustrated inFIG.2the cartomizer2may comprise a body4comprising the reservoir5, the heater18, an aerosol chamber7, at least one first air inlet11and at least one aerosol outlet16.

The reservoir5is arranged for storing an aerosol-forming liquid (or e-liquid) comprising at least first and second mixed compounds having respectively first bp1and second bp2boiling points.

The heater18is arranged for vaporizing (or aerosolizing) the aerosol-forming liquid mixed with air in the aerosol chamber7in order to generate an aerosol.

The (each) first air inlet11is set upstream the aerosol chamber7and in fluid communication therewith, in order to supply it with air originating from outside.

The (each) aerosol outlet16is set downstream the aerosol chamber7and in fluid communication therewith, in order to receive the generated aerosol when a user of the aerosol generation device1inhales during a vaping session.

For instance, and as illustrated in the non-limiting example ofFIG.2, the cartomizer body4may comprise an internal wall6defining the aerosol chamber7. Also for instance, this internal wall6may have an annular shape. The aerosol chamber7is fed with air (sucked in by the user) through each first air inlet11defined in the internal wall6(as illustrated by the two small arrows B inFIG.2). This air comes from outside through at least one second air inlet12defined in the body4(as illustrated by the arrow C inFIG.2). But, each second air inlet12could be defined in a wall of the body13of the electrical and control device3.

Also for instance, and as illustrated in the non-limiting example ofFIG.2, the cartomizer body4may comprise a mouthpiece8comprising the (each) aerosol outlet16and allowing the user to inhale the generated aerosol through this aerosol outlet16during a vaping session (as illustrated by the arrows A inFIG.2). In this case, the aerosol chamber7is fluidly coupled to the mouthpiece8by a central conduit (or passage)9leading to the aerosol outlet16. Also for instance, the mouthpiece8may be integral with an end10of the cartomizer body4that receives the generated aerosol from the central conduit9. But this mouthpiece8could be an additional part coupled to the cartomizer body4.

Also for instance, and as illustrated in the non-limiting example ofFIG.2, the cartomizer body4may comprise an outer wall17defining a cavity, and the reservoir5may be delimited at least partially by this outer wall17and the central conduit9.

In the illustrated example, the aerosol chamber7comprises the heater18that is arranged for heating the aerosol-forming liquid (originating from the reservoir5) to generate the aerosol, when it receives electrical power (or energy) originating from the power source23of the electrical and control device3. This heater18may be a resistive heater, such as a resistive coil, and/or an inductive heater, such as a metallic susceptor. In this case, the heater18may comprise one or more electrically activated resistive and/or inductive heating elements. The heating can be made by conduction, convection and/or radiation.

For instance, the aerosol-forming liquid can leave the reservoir5to reach the aerosol chamber7(see the four arrows D) through openings15defined in the internal wall6.

Also for instance, and as illustrated in the non-limiting example ofFIG.2, the reservoir5may have an annular shape and a central passage defining the central conduit (or aerosol passage)9.

Also for instance, and as illustrated in the non-limiting example ofFIG.1, the body13of the electrical and control device3may define a housing26intended for receiving a part of the cartomizer body4.

Also for instance, and as illustrated in the non-limiting example ofFIGS.1and2, the coupling between the cartomizer body4and the body13of the electrical and control device3can be done by permanent magnets24that may be located in the housing26and intended for attracting corresponding elements25of the cartomizer body4. But in a variant of embodiment not illustrated, the coupling between the cartomizer body4and the body13of the electrical and control device3could be done by screwing by means of corresponding threaded portions, for instance.

As illustrated inFIG.1the body13of the electrical and control device3may comprise at least the controller (or control device)27and a possible user interface28in addition to the power source23(storing electrical energy).

For instance, the power source23may be a rechargeable battery. In this case the body13may comprise an electrical connector to which a charger cable may be connected during a charging session of the rechargeable battery23. Such a charger cable may be coupled to an (AC) adapter or to a wall socket.

The controller27is electrically coupled to the power source23and controls the operation of the cartomizer2(and notably its heater18) during a vaping session and also during a possible charging session. For instance, and as illustrated in the non-limiting example ofFIG.1, the controller27may be fixed onto a printed circuit board29(housed in the body13).

Explicit use of the term “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read only memory (ROM) for storing software, random access memory (RAM), and non volatile storage. Other hardware, conventional and/or custom, may also be included. The functions of the controller27may be carried out through the operation of program logic, through dedicated logic, through the interaction of program control and dedicated logic, or even manually (by the user). These functions may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software.

The possible user interface28is coupled to the controller27and the power source23to allow the user to control at least partly the controller27. For instance, the user interface28may comprise a display (such as a screen or light emitting diode (or LED)-type interface) arranged for displaying information relative to a current vaping session or a possible current charging session and for allowing the user to control the controller27. Also for instance, and as illustrated in the non-limiting example ofFIG.1, the user interface28may be fixed partly to the printed circuit board29to ease and simplify its connections with the controller27.

Also for instance, the cartomizer2and the electrical and control device3may comprise respectively electrical pins intended for contacting each other during their coupling to allow the feeding of the heater18with electrical power (or energy) during a vaping session.

Also for instance, and as illustrated in the non-limiting example ofFIG.2, the aerosol chamber7may comprise an aerosol-forming liquid transport element33to transport aerosol-forming liquid from the openings15of the internal wall6to the heater18. For instance, this aerosol-forming liquid transport element33may be a capillary element (possibly a capillary wick) having two opposite ends set in front of the openings15, and possibly against the latter (and therefore against the internal surface of the internal wall6). But in a variant of embodiment not illustrated, the aerosol-forming liquid transport element33may traverse two large openings (larger than those referenced15) and defined in the internal wall6to finish in the reservoir5. These large openings may seal the aerosol-forming liquid transport element33at its circumference to avoid by-pass of liquid around it. The capillary element33can be a fiber or ceramic rod, for instance. For instance, the heater18may comprise a resistive coil wound around the capillary element33and connected to internal electrodes via lead wires. In this case the windings of the heater18define a heating area comprising at least a part of the capillary element33and in which the aerosol-forming liquid (to be heated and originating from the reservoir5) is introduced.

According to the invention, the controller27is arranged for controlling supply of electrical power (ep) to the heater18, during each inhalation phase of a vaping session, according to a chosen electrical power profile. More precisely, in this chosen profile the electrical power varies over time depending on the first bp1and second bp2boiling points in order to control the vaporization ratio of the first and second compounds in the aerosol chamber7(and more particularly in the heating area).

It should be understood that the control of the level of the electrical power and of the duration at such a level allows to control the vaporization ratio of the first and second compounds when taking also into account the difference between the boiling points of these first and second compounds. So, the profile depends on the first and second compounds, and allows reducing the spitting effect since the vaporization ratio, and therefore the ratio of vapor bubbles (rich of first compound) over unvaporized liquid droplets (rich of second compound) in the heating area, can be now controlled.

Preferably, the controller27is arranged for controlling the supply of the heater18according to a chosen profile that allows minimizing the vaporization ratio of the first and second compounds in the aerosol chamber7.

In a first example of embodiment illustrated non-limitatively inFIG.3, the controller27may be arranged for controlling the supply of the heater18according to a chosen profile comprising three successive phases. The first phase p11has a first duration d11at a first electrical power ep11. The second phase p12has a second duration d12at a second electrical power ep12greater than the first electrical power ep11. The third phase p13has a third duration d13at a third electrical power ep13greater than the second electrical power ep12. For instance, the first electrical power ep11corresponds to a low power, the second electrical power ep12corresponds to a medium power, and the third electrical power ep13corresponds to a high power.

This first example of embodiment allows minimization of the temperature rise difference to achieve a reduction of the vaporization ratio vr1and therefore of the spitting effect.

Also for instance, and as illustrated inFIG.3, in this first example of embodiment the first d11, second d12and third d13durations may be equal to a chosen first value v1. But they could be different one from the other.

Also for instance, in this first example of embodiment the chosen first value v1may be comprised between 150 ms and 250 ms. As an illustrative example, well adapted to the case where the first and second compounds are respectively propylene glycol and vegetable glycerin/glycerol, the chosen first value v1may be equal to 200 ms. But other first values v1may be used, preferably as long as the sum of the first d11, second d12and third d13durations remains smaller or equal to the duration of a “standard puff” (which is generally considered equal to 3 s).

In a second example of embodiment illustrated non-limitatively inFIG.4, the controller27may be arranged for controlling the supply of the heater18according to a chosen profile comprising five successive phases. The first phase p21has a first duration d21at a first electrical power ep13. The second phase p22has a second duration d22at an electrical power equal to zero. The third phase p23has a third duration d23at the first electrical power ep13. The fourth phase p24has a fourth duration d24at an electrical power equal to zero. The fifth phase p25has a fifth duration d25at the first electrical power ep13. For instance, the first electrical power ep13corresponds to a high power.

This second example of embodiment allows reducing the time to first vapor whilst achieving a minimal spitting effect. The high power required to achieve the high aerosol output could be applied in short bursts first to allow the first and second compounds to rise up closer together to achieve a reduction of the vaporization ratio vr2and therefore of the spitting effect.

For instance, and as illustrated inFIG.4, in this second example of embodiment the first d21, third d23and fifth d25durations may be equal to a chosen second value v2. But they could be different one from the other, preferably as long as the sum of the first d21, second d22, third d23, fourth d24and fifth d25durations remains smaller or equal to the duration of a “standard puff” (which is generally considered equal to 3 s).

Also for instance, in this second example of embodiment the chosen second value v2may be comprised between 70 ms and 130 ms. As an illustrative example, well adapted to the case where the first and second compounds are respectively propylene glycol and vegetable glycerin/glycerol, the chosen second value v2may be equal to 100 ms. But other second values v2may be used, preferably as long as the sum of the first d21, second d22, third d23, fourth d24and fifth d25durations remains smaller or equal to the duration of a standard puff.

Also for instance, and as illustrated inFIG.4, in this second example of embodiment the second d22and fourth d24durations may be equal to a chosen third value v3. But they could be different one from the other.

For instance, this chosen third value v3may be comprised between 10 ms and 50 ms. As an illustrative example, well adapted to the case where the first and second compounds are respectively propylene glycol and vegetable glycerin/glycerol, the chosen third value v3may be equal to 30 ms. But other third values v3may be used, preferably as long as the sum of the first d21, second d22, third d23, fourth d24and fifth d25durations remains smaller or equal to the duration of a standard puff.

In a third example of embodiment illustrated non-limitatively inFIG.5, the controller27may be arranged for controlling the supply of the heater18according to a chosen profile comprising a single phase p4having a chosen duration d4during which the electrical power ep strictly increases.

This third example of embodiment allows to control the difference in the rate of change of temperature in the first and second compounds to reduce the vaporization ratio vr3and therefore the spitting effect. This means that it will take longer for the spitting effect to happen, but this is not a problem since the control delays the spitting effect beyond the time of a standard puff, or at the very least the spitting effect will occur for a shorter duration and will therefore be reduced.

For instance, and as illustrated inFIG.5, in this third example of embodiment the chosen profile may comprise a phase p4during which the electrical power ep varies as a logarithmic function.

Also for instance, in this third example of embodiment the chosen duration d4may be comprised between 550 ms and 650 ms. As an illustrative example, well adapted to the case where the first and second compounds are respectively propylene glycol and vegetable glycerin/glycerol, the chosen duration d4may be equal to 600 ms. But other chosen durations d4may be used.

It should be noticed that the invention can also be considered as a control method intended for controlling aerosol generation by the aerosol generation device1. This control method comprises a step in which the controller27controls the supply of the heater18according to a chosen profile in which the electrical power varies over time depending on the first bp1and second bp2boiling points in order to control a vaporization ratio of the first and second compounds in the aerosol chamber7.

It should be appreciated by those skilled in the art that some block diagrams ofFIGS.1and2herein represent conceptual views of illustrative elements embodying the principles of the invention.