Aerosol Generating System and Device

Abstract

An aerosol generating system includes an induction heatable susceptor, an induction coil arranged to generate a time varying electromagnetic field for inductively heating the induction heatable susceptor, a power source for supplying power to the induction coil and a controller. The controller is arranged to detect the self-resonant frequency of the induction coil and to control the operation of the aerosol generating system based on the detected self-resonant frequency. An aerosol generating device is also described.

Claims

1. An aerosol generating system comprising: an induction heatable susceptor; an induction coil arranged to generate a time varying electromagnetic field for inductively heating the induction heatable susceptor; a power source for supplying power to the induction coil; and a controller; wherein the controller is arranged to detect the self-resonant frequency of the induction coil and to control the operation of the aerosol generating system based on the detected self-resonant frequency.

2. The aerosol generating system according to claim 1, wherein the controller is arranged to control the amount of power supplied by the power source to the induction coil based on the detected self-resonant frequency.

3. The aerosol generating system according to claim 2, wherein the controller stores a first type of reference value and is further arranged to control the amount of power supplied by the power source to the induction coil based on the first type of reference value.

4. The aerosol generating system according to claim 1 for use with an aerosol generating article comprising an aerosol generating material, wherein the controller is arranged to detect the type of aerosol generating article used with the aerosol generating system based on the detected self-resonant frequency of the induction coil, preferably when the induction coil is supplied with a predetermined amount of power and/or when the induction coil is operated according to a predetermined power profile.

5. The aerosol generating system according to claim 4, wherein the controller stores a second type of reference value and is further arranged to detect the type of aerosol generating article based on the second type of reference value.

6. The aerosol generating system according to claim 5, wherein the controller stores a plurality of the second type of reference values and a corresponding plurality of predetermined heating profiles adapted for use with different types of aerosol generating articles, and the controller is arranged to select one of the plurality of predetermined heating profiles based on the plurality of second type of reference values and the detected self-resonant frequency.

7. The aerosol generating system according to claim 6, wherein one or more of the plurality of second type of reference values corresponds to an aerosol generating article that is not suitable for use with the aerosol generating system and the controller is adapted to cease supplying power to the induction coil upon detecting the use of an unsuitable aerosol generating article.

8. The aerosol generating system according to claim 1, wherein the controller is arranged to detect an inhalation by a user of the system based on the detected self-resonant frequency and based on the amount of power supplied by the power source to the induction coil at the time of detection and/or at least part of a predetermined power profile before the time of detection.

9. The aerosol generating system according to claim 8, wherein the controller stores a third type of reference value and is further arranged to detect an inhalation by a user based on the third type of reference value.

10. The aerosol generating system according to claim 1, wherein the controller is arranged to: detect a timing change of an aerosol generating article used with the system based on the detected self-resonant frequency and based on the amount of power supplied by the power source to the induction coil at the time of detection and/or at least part of a predetermined power profile before the time of detection; and indicate the detected timing change and/or cease supplying power to the induction coil.

11. The aerosol generating system according to claim 10, wherein the controller stores a fourth type of reference value and is further arranged to detect a timing change of an aerosol generating article based on the fourth type of reference value.

12. The aerosol generating system according to claim 1, wherein the controller is arranged to: detect an unexpected event based on the detected self-resonant frequency and based on the amount of power supplied by the power source to the induction coil at the time of detection and/or at least part of a predetermined power profile before the time of detection; and indicate the detected unexpected event and/or cease supplying power to the induction coil.

13. The aerosol generating system according to claim 12, wherein the controller stores a fifth type of reference value and is further arranged to detect an unexpected event based on the fifth type of reference value.

14. An aerosol generating device comprising: a space for receiving an aerosol generating article; an induction coil arranged to generate a time varying electromagnetic field; a power source for supplying power to the induction coil; and a controller; wherein the controller is arranged to detect the self-resonant frequency of the induction coil and to control the operation of the aerosol generating device based on the detected self-resonant frequency.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG. 1 is a diagrammatic view of an example of an aerosol generating system;

[0056] FIG. 2 is a schematic representation of a methodology for temperature control of an aerosol generating article used with the aerosol generating system of FIG. 1;

[0057] FIG. 3 is a schematic representation of a methodology for detecting a type of aerosol generating article used with the aerosol generating system of FIG. 1;

[0058] FIG. 4 is a schematic representation of a methodology for detecting inhalation by a user during use of the aerosol generating system of FIG. 1;

[0059] FIG. 5 is a schematic representation of a methodology for detecting the timing change of an aerosol generating article used with the aerosol generating system of FIG. 1; and

[0060] FIG. 6 is a schematic representation of a methodology for detecting an unexpected event during use of the aerosol generating system of FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS

[0061] Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

[0062] Referring initially to FIG. 1, there is shown diagrammatically an example of an aerosol generating system 1. The aerosol generating system 1 comprises an aerosol generating device 10 and an aerosol generating article 24. The aerosol generating device 10 has a proximal end 12 and a distal end 14 and comprises a device body 16 which includes a power source 18 and a controller 20 which may be configured to operate at high frequency. The power source 18 typically comprises one or more batteries which could, for example, be inductively rechargeable.

[0063] The aerosol generating device 10 is generally cylindrical and comprises a generally cylindrical aerosol generating space 22, for example in the form of a heating compartment, at the proximal end 12 of the aerosol generating device 10. The cylindrical aerosol generating space 22 is arranged to receive a correspondingly shaped generally cylindrical aerosol generating article 24 containing an aerosol generating material 26 and one or more induction heatable susceptors 28. The aerosol generating article 24 typically comprises a non-metallic cylindrical outer shell 24a and an air-permeable layer or membrane 24b, 24c at the proximal and distal ends to contain the aerosol generating material 26 and allow air to flow through the aerosol generating article 24. The aerosol generating article 24 is a disposable article which may, for example, contain tobacco as the aerosol generating material 26.

[0064] The aerosol generating device 10 comprises a helical induction coil 30 which has a circular cross-section and which extends around the cylindrical aerosol generating space 22. The induction coil 30 can be energised by the power source 18 and controller 20. The controller 20 includes, amongst other electronic components, an inverter which is arranged to convert a direct current from the power source 18 into an alternating high-frequency current for the induction coil 30.

[0065] The aerosol generating device 10 includes one or more air inlets 32 in the device body 16 which allow ambient air to flow into the aerosol generating space 22. The aerosol generating device 10 also includes a mouthpiece 34 having an air outlet 36. The mouthpiece 34 is removably mounted on the device body 16 at the proximal end 12 to allow access to the aerosol generating space 22 for the purposes of inserting or removing an aerosol generating article 24.

[0066] As will be understood by one of ordinary skill in the art, when the induction coil 30 is energised during use of the aerosol generating system 1, an alternating and time-varying electromagnetic field is produced. This couples with the one or more induction heatable susceptors 28 and generates eddy currents and/or magnetic hysteresis losses in the one or more induction heatable susceptors 28 causing them to heat up. The heat is then transferred from the one or more induction heatable susceptors 28 to the aerosol generating material 26, for example by conduction, radiation and convection.

[0067] The induction heatable susceptor(s) 28 can be in direct or indirect contact with the aerosol generating material 26, such that when the susceptor(s) 28 is/are inductively heated by the induction coil 30, heat is transferred from the susceptor(s) 28 to the aerosol generating material 26, to heat the aerosol generating material 26 and thereby produce an aerosol. The aerosolisation of the aerosol generating material 26 is facilitated by the addition of air from the surrounding environment through the air inlets 32. The aerosol generated by heating the aerosol generating material 26 exits the aerosol generating space 22 through the air outlet 36 where it can be inhaled by a user of the device 10. The flow of air through the aerosol generating space 22, i.e. from the air inlets 32, through the aerosol generating space 22 and out of the air outlet 36, can be aided by negative pressure created by a user drawing air from the air outlet 36 side of the device 10.

[0068] The induction coil 30 forms part of a tuned circuit with the induction heatable susceptor(s) 28 of the aerosol generating article 24 and has a self-resonant frequency which may vary. The controller 20 is arranged to detect the self-resonant frequency of the induction coil 30 and to control the operation of the aerosol generating system 1 and device 10 based on the detected self-resonant frequency.

[0069] In a first example illustrated in FIG. 2 which is suitable for controlling the temperature of the aerosol generating article 24, there is a linear relationship between the temperature of the induction heatable susceptor(s) 28 and the self-resonant frequency of the induction coil 30. As noted above, this is because the induction coil 30 forms part of a tuned circuit with the induction heatable susceptor(s) 28 and it therefore follows that a change in the temperature of the induction heatable susceptor(s) 28 causes a change in the self-resonant frequency of the induction coil 30. It is, therefore, possible to indirectly determine the temperature of the induction heatable susceptor(s) 28 by arranging the controller 20 to determine the self-resonant frequency of the induction coil 30. Furthermore, the controller 20 is arranged to control the temperature of the induction heatable susceptor(s) 28 based on the detected self-resonant frequency by controlling the amount of power supplied by the power source 18 to the induction coil 30 based on the detected self-resonant frequency.

[0070] In a typical implementation and as best seen in FIG. 2, the controller 20 stores a first type of reference value 40, namely the value of a self-resonant frequency itself or a certain value calculated based on the value of the self-resonant frequency, which corresponds to a target operating temperature 42 of the induction heatable susceptor(s) 28. If the controller 20 determines that the detected value of the self-resonant frequency or the value calculated based on the detected value of the self-resonant frequency differs from, e.g. is higher than, the first type of reference value 40, the controller 20 determines that the temperature of the induction heatable susceptor(s) 28 is higher than the target temperature 42 and reduces the amount of power supplied by the power source 18 to the induction coil 30. In doing so, the temperature of the induction heatable susceptor(s) 28 is reduced to a value which is substantially equal to the target operating temperature thereby shifting the value of the self-resonant frequency of the induction coil 30 or the value calculated based on the value of the self-resonant frequency to a value which is substantially equal to the first type of reference value 40. Similarly, if the controller 20 determines that the detected value of the self-resonant frequency or the value calculated based on the detected value of the self-resonant frequency differs from, e.g. is lower than, the first type of reference value 40, the controller 20 determines that the temperature of the induction heatable susceptor(s) 28 is lower than the target temperature 42 and increases the amount of power supplied by the power source 18 to the induction coil 30. In doing so, the temperature of the induction heatable susceptor(s) 28 is increased to a value which is substantially equal to the target operating temperature thereby shifting the value of the self-resonant frequency of the induction coil 30 or the value calculated based on the value of the self-resonant frequency to a value which is substantially equal to the first type of reference value 40.

[0071] In a second example illustrated in FIG. 3, the controller 20 is arranged to detect the type of aerosol generating article 24 (e.g. type A or type B) used with the aerosol generating system 1 based on the detected self-resonant frequency of the induction coil 30 or based on a value calculated based on the value of the detected self-resonant frequency when the induction coil 30 is supplied with a predetermined amount of power and/or when the induction coil 30 is operated according to a predetermined power profile. In the illustrated example, the controller 20 stores a plurality of a second type of reference values 50 (e.g. Value A, Value B, Value C).

[0072] The particular type of aerosol generating article 24 used with the aerosol generating system 1 can be determined by detecting the self-resonant frequency of the induction coil 30 or a value calculated based on the value of the detected self-resonant frequency because, as noted above, the induction coil 30 forms part of a tuned circuit with the induction heatable susceptor(s) 28. Thus, the physical properties of the induction heatable susceptor(s) 28, including, e.g., material and thickness, influence the self-resonant frequency of the induction coil 30 during operation of the aerosol generating system 1. By positioning one or more induction heatable susceptors 28 with different characteristics inside different types of aerosol generating article 24, the self-resonant frequency of the induction coil 30 can be controlled in a known manner and the self-resonant frequency or a value calculated based on the value of the self-resonant frequency can, thus, be used to reliably detect the type of aerosol generating article 24 that is used with the aerosol generating system 1.

[0073] Different types of aerosol generating article 24 may contain different types of aerosol generating material 26 and/or may have different moisture and humectant content. Different types of aerosol generating article 24 may require different heating profiles to ensure that an aerosol with optimum characteristics is generated when the aerosol generating article 24 is used with the aerosol generating device 10. Different heating profiles may, for example, have different rates of heating (e.g. rapid/slow), different maximum and/or minimum operating temperatures and different time periods for which such operating temperatures are maintained.

[0074] As mentioned above, the controller 20 stores a plurality of the second type of reference values 50 (Value A, Value B, Value C). The controller 20 also stores a plurality of predetermined heating profiles (heating profile A, heating profile B) which are adapted for use with different types of aerosol generating article 24. In one implementation and following insertion of an aerosol generating article 24 into the aerosol generating space 22, the controller 20 is arranged to detect the self-resonant frequency of the induction coil 30 or a value calculated based on the value of the detected self-resonant frequency and to compare the detected self-resonant frequency or the value calculated based on the value of the detected self-resonant frequency with the plurality of second type of reference values. The controller 20 is arranged to identify the type of aerosol generating article 24 based on the comparison and to select a heating profile based on the comparison. For example, if the controller 20 determines that the detected self-resonant frequency or the value calculated based on the value of the detected self-resonant frequency has a value between A and B as shown in FIG. 3, the controller 20 determines that the aerosol generating article 24 is of type A and selects heating profile A. The controller 20 then controls the power supplied by the power source 18 to the induction coil 30 to provide heating profile A and indicates to a user that an aerosol generating article 24 of type A has been positioned in the aerosol generating space 22. Similarly, if the controller 20 determines that the detected self-resonant frequency or the value calculated based on the value of the detected self-resonant frequency has a value between B and C as shown in FIG. 3, the controller 20 determines that the aerosol generating article 24 is of type B and selects heating profile B. The controller 20 then controls the power supplied by the power source 18 to the induction coil 30 to provide heating profile B and indicates to a user that an aerosol generating article 24 of type B has been positioned in the aerosol generating space 22.

[0075] In some implementations, one or more of the plurality of second type of reference values 50 can correspond to aerosol generating articles 24 that are not suitable for use with the aerosol generating system 1. If the controller 20 detects that the self-resonant frequency or the value calculated based on the value of the detected self-resonant frequency corresponds to a second type of reference value which indicates that an aerosol generating article 24 that is not suitable for use with the system 1 has been positioned in the aerosol generating space 22, the controller 20 can terminate the supply of power to the induction coil 30 from the power source 18 and indicate to a user an error state. For example, if the controller 20 determines that the detected self-resonant frequency or the value calculated based on the value of the detected self-resonant frequency is not in the range between Value A and Value C as shown in FIG. 3, the controller 20 determines that the aerosol generating article 24 is not suitable for use with the aerosol generating system 1. The controller 20 then ceases supplying power from the power source 18 to the induction coil 30 and indicates an error state to a user. A typical example of an unsuitable aerosol generating article 24 is an article which is off-specification and unsuitable for use with the aerosol generating system 1. Other non-limiting examples include an aerosol generating article 24 which has been previously used and which, upon further use, is incapable of generating an aerosol with suitable characteristics due to depletion of the aerosol generating material 26 and an aerosol generating article 24 which has been incorrectly positioned within the aerosol generating space 22 thus preventing the induction heatable susceptor(s) from being optimally coupled with the electromagnetic field generated by the induction coil 30.

[0076] In a third example illustrated in FIG. 4, the controller 20 is arranged to detect an inhalation (or puff) by a user of the system 1 based on the detected self-resonant frequency of the induction coil 30 or a certain value calculated based on the value of the detected self-resonant frequency and based on the amount of power supplied by the power source 18 to the induction coil 30 at the time of detection and/or at least part of a predetermined power profile before the time of detection. The controller 20 stores a third type of reference value and may be further arranged to detect a puff by a user based on the third type of reference value.

[0077] In one implementation, the controller 20 determines a marker value for a puff (MVP) based on the detected self-resonant frequency (DSRF) as follows:

[00001]$\mathrm{MVP}=\frac{\Delta \mathrm{DSRF}}{\Delta t}$ [0078] where: [0079] ADSRF=DSRF at time a−DSRF at time b; and [0080] Δt=time a−time b.

[0081] It will be understood that when a user inhales aerosol through the mouthpiece 34, the flow of ambient air through the air inlets 32 and into the aerosol generating article 24 causes a decrease in the temperature of the aerosol generating article 24 and, hence, a decrease in the temperature of the induction heatable susceptor(s) 28. As explained above in connection with FIG. 2, a decrease in the temperature of the induction heatable susceptor(s) causes a decrease in the self-resonant frequency of the induction coil 30 which is detected by the controller 20. By detecting the change in the self-resonant frequency or a value calculated based on the self-resonant frequency between two predetermined points in time, namely time a and time b, the controller 20 is able to determine the marker value for puff (MVP) in the manner described above. The controller 20 compares the marker value for puff (MVP) with the third type of reference value and, if the controller 20 determines that the marker value for puff (MVP) is greater than the stored third type of reference value, the controller 20 determines that a puff has occurred.

[0082] In a fourth example illustrated in FIG. 5, the controller 20 is arranged to detect a timing change of an aerosol generating article 24 used with the system 1 based on the detected self-resonant frequency or a value calculated based on the value of the detected self-resonant frequency and based on the amount of power supplied by the power source 18 to the induction coil 30 at the time of detection and/or at least part of a predetermined power profile before the time of detection. The controller 20 is also arranged to indicate the detected timing change so that a user can replace the aerosol generating article 24 and/or to cease supplying power to the induction coil to prevent further use of the aerosol generating device 10 until the aerosol generating article 24 has been replaced by the user.

[0083] FIG. 5 illustrates a linear relationship between the amount of power supplied by the power source 18 to the induction coil 30 and the self-resonant frequency of the induction coil 30. As will be understood by one of ordinary skill in the art, as the moisture and humectant content of the aerosol generating material 26 within an aerosol generating article 24 is depleted over time, the temperature of the aerosol generating article 24, and hence of the induction heatable susceptor(s) 28, increases with continued use when the same amount of power is supplied by the power source 18 to the induction coil 30. Since the self-resonant frequency of the induction coil 30 is affected by the temperature of the induction heatable susceptor(s) 28 as explained above, a change in the detected self-resonant frequency or a value calculated based on the value of the detected self-resonant frequency can be used by the controller 20 to determine that the aerosol generating article 24 needs to be replaced.

[0084] In one implementation, the controller 20 stores a fourth type of reference value 60 and is arranged to detect a timing change of the aerosol generating article 24 based on the fourth type of reference value 60. The fourth type of reference value 60 is typically a self-resonant frequency range or a range calculated based on the self-resonant frequency range which corresponds to a target temperature range of the induction heatable susceptor(s) 28.

[0085] For example, it will be seen in FIG. 5 that if the self-resonant frequency detected by the controller 20 or the value calculated based on the detected self-resonant frequency is less than the fourth type of reference value 60, in other words in Area B, the controller 20 detects that the self-resonant frequency or the value calculated based on the detected self-resonant frequency (and hence the temperature of the induction heatable susceptor(s) 28) is within the normal operating range, thus indicating that there is sufficient humectant and moisture content within the aerosol generating article 24 and that replacement of the aerosol generating article 24 is not yet needed. If, on the other hand, the self-resonant frequency detected by the controller 20 or the value calculated based on the detected self-resonant frequency is greater than the fourth type of reference value 60, in other words in Area A, the controller 20 detects that the self-resonant frequency or the value calculated based on the detected self-resonant frequency (and hence the temperature of the induction heatable susceptor(s) 28) is higher than the normal operating range, thus indicating that there is insufficient humectant and moisture content within the aerosol generating article 24 and that the aerosol generating article 24 needs to be replaced. In these circumstances, the controller 20 can indicate to a user that the aerosol generating article needs to be replaced (for example via a visual alert and/or an audible alert and/or a tactile alert) and/or can cease supplying power to the induction coil 30 from the power source 18 to prevent continued operation of the aerosol generating system 1 with the depleted aerosol generating article 24.

[0086] In a fifth example illustrated in FIG. 6, the controller 20 is arranged to detect an unexpected event based on the detected self-resonant frequency of the induction coil 30 or a value calculated based on the value of the detected self-resonant frequency and based on the amount of power supplied by the power source 18 to the induction coil 30 at the time of detection and/or at least part of a predetermined power profile before the time of detection. The controller 20 is also arranged to indicate the detected unexpected event and/or cease supplying power to the induction coil 30.

[0087] The controller 20 stores a fifth type of reference value 70 which is typically a self-resonant frequency or a value calculated based on the value of the self-resonant frequency which corresponds to a target operating temperature of the induction heatable susceptor(s) 28 and is arranged to detect an unexpected event by comparing the detected self-resonant frequency of the induction coil 30 or the value calculated based on the detected self-resonant frequency with the fifth type of reference value 70. Detection of an unexpected event is, thus, based on the methodology described above with reference to FIG. 2.

[0088] In a first example, the unexpected event may be that the temperature of the induction heatable susceptor(s) 28 is less than expected, for example less than the target operating temperature. In this first example, the controller 20 detects that the self-resonant frequency of the induction coil 30 or the value calculated based on the detected self-resonant frequency is less than the self-resonant frequency or the value calculated based on the self-resonant frequency corresponding to the fifth type of reference value 70, in other words that it is less than the self-resonant frequency or value which corresponds to the target operating temperature of the induction heatable susceptor(s) 28. This could, for example, occur in the event of attempted use of the aerosol generating system 1 when the ambient temperature is too low.

[0089] In a second example, the unexpected event may be that the temperature of the induction heatable susceptor(s) 28 is greater than expected, for example greater than the target operating temperature. In this second example, the controller 20 detects that the self-resonant frequency of the induction coil 30 or the value calculated based on the detected self-resonant frequency is greater than the self-resonant frequency or the value calculated based on the self-resonant frequency corresponding to the fifth type of reference value 70, in other words that it is greater than the self-resonant frequency or value which corresponds to the target operating temperature of the induction heatable susceptor(s) 28. This could, for example, occur in the event of attempted use of the aerosol generating system 1 when the ambient temperature is too high.

[0090] It will be understood by one of ordinary skill in the art that the example control methodologies described above with reference to the drawings are not mutually exclusive and that all, or a selection, of the control methodologies can be implemented by the controller 20 to provide enhanced control of the aerosol generating system 1.

[0091] Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments.

[0092] Any combination of the above-described features in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[0093] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.