Temperature measurement system for an aerosol generating device, an aerosol generating device equipped with a temperature measurement system, and a method for measuring the temperature in an aerosol generating device

Abstract

A temperature measurement system for an aerosol generating device according to the invention comprises a magnetic field source, a ferromagnetic or ferrimagnetic body, and a force sensor configured to measure an attractive force between the magnetic field source and the ferromagnetic or ferrimagnetic body. The temperature measurement system further comprises a memory in which pre-recorded data is stored associating at least one force value with a value indicative of a temperature of the ferromagnetic or ferrimagnetic body, and a control unit configured to determine temperature information based on the measured force values ​​from the force sensor and the pre-recorded data. A method for measuring a temperature in an aerosol generating device according to the invention comprises the steps of providing a magnetic field source, a ferromagnetic or ferrimagnetic body, and a force sensor, measuring the attractive force between the magnetic field source and the ferromagnetic or ferrimagnetic body with the force sensor, and determining temperature information based on the measured force values ​​obtained from the force sensor and the pre-recorded data associating at least one force value with a value indicative of a temperature of the ferromagnetic or ferrimagnetic body.

Description

[Technical field]

[0001] The present invention relates generally to the field of aerosol generating devices. In particular, the present invention is directed to a temperature measurement system for an aerosol generating device, an aerosol generating device equipped with such a temperature measurement system, and a method for measuring temperature within an aerosol generating device. [Background technology]

[0002] In recent years, devices that heat, rather than burn or combust, a substance to generate a vapor or aerosol intended for inhalation by a user have become increasingly popular.

[0003] Such commonly used devices typically use tobacco and / or other suitable substances that are heated, rather than burned, to generate an inhalable aerosol, which may also be referred to as an aerosol-generating material, and the device may also be referred to as an aerosol-generating device.

[0004] Typically, the aerosol-generating material is placed in a container, also called a stick or tobacco stick, which can be inserted into and removed from the aerosol-generating device by a user, in other words, the stick or tobacco stick is a consumable item.

[0005] Typically, a user inserts a consumable into a heating section of an aerosol generating device, also known as a heating chamber or oven chamber. When the user has inserted the consumable into the heating section, the user can turn on the heating of the aerosol generating device by operating an operating button. The user then waits until the heating has progressed to a state where the heated aerosol generating material generates an aerosol that can be consumed by the user.

[0006] In this context, the temperature of the aerosol-generating substance plays an important role in the use of the aerosol generating device. On the one hand, it is necessary to reach a minimum temperature of the aerosol-generating substance in order to obtain an adequate amount of aerosol. On the other hand, extremely high temperatures should also be avoided, for example because polymer layers in the fluid chamber and nozzle may start to melt, and because the aerosol ejected from the aerosol generating device may burn or be too hot for the user to consume. Furthermore, excessively high temperatures may result in the formation of undesirable or even harmful components in the aerosol. In addition, different types of aerosol-generating substances may require different temperatures for aerosol generation. Finally, users of aerosol generating devices may have different personal preferences regarding the preferred heating temperature of the aerosol-generating substance.

[0007] In view of the above, there is a need to measure the temperature of the aerosol-generating material. However, due to the limited space available within the oven chamber, it is inherently difficult to measure the temperature within the consumable itself or even in direct proximity to the consumable. Furthermore, the accuracy of the temperature probe may be compromised by the type of heating employed, for example when a conductive temperature probe is inserted into an oven chamber that is heated by induction heating.

[0008] Thus, previously known devices focus their safety measures on avoiding excessively high temperatures.

[0009] For example, EP 3606363 A1 proposes to hold and heat the aerosol-forming liquid by an open-porous, inductively heatable ceramic material, where heating occurs mainly or exclusively as a result of hysteresis losses. The material is preferably ferrimagnetic or ferromagnetic and non-conductive. In this case, the inductive heatability essentially disappears above the Curie temperature. This effect is used to control the maximum heating temperature of the susceptor.

[0010] EP 3788893 A1 discloses an aerosol generating device comprising a housing and a control unit. The housing comprises a cavity for inserting an aerosol-generating article and a magnetic element. If an excessively high temperature is detected, the magnetic element control module controls the magnetic element to generate a magnetic repulsive force against the aerosol-generating article such that the aerosol-generating article is displaced.

[0011] An alternative approach is pursued in Korean Patent No. 102231229B1, which suggests providing a diamagnetic or paramagnetic material between the heating body and the temperature measuring device, thereby minimizing the maximum measurement error caused by eddy currents caused by the electromagnetic waves of the coil. In other words, the temperature of the heating body is measured indirectly in this document.

[0012] The document CN110236230A relates to a temperature control device for an electronic cigarette, which comprises a thermocouple, an electromotive force sampling circuit and a control module. The high temperature end of the temperature difference thermocouple is connected to the atomizer of the electronic cigarette, and the electromotive force sampling circuit is connected to the low temperature end. The control module is connected to the electromotive force sampling circuit and the temperature sensor. The control module obtains the electromotive force according to the temperature information at the low temperature end of the thermocouple and a pre-set temperature-electromotive force comparison table. The temperature of the high temperature end is obtained in real time with the help of the temperature-electromotive force comparison table, thereby controlling the temperature of the atomizer. Summary of the Invention [Means for solving the problem]

[0013] The present invention is intended to address one or more of the technical problems mentioned above. One or more of these problems may be remedied by the subject matter of the independent claims. Further preferred embodiments are defined in the dependent claims.

[0014] In particular, in consideration of the problems discussed above, the inventors have devised a temperature measurement system for an aerosol generating device comprising a magnetic field source, a ferromagnetic body, and a force sensor configured to measure an attractive force between the magnetic field source and the ferromagnetic body, the temperature measurement system further comprising a memory in which pre-recorded data relating at least one force value to a value indicative of a temperature of the ferromagnetic body is stored, and a control unit configured to determine temperature information based on the measured force values ​​from the force sensor and the pre-recorded data.

[0015] In particular, the inventors have surprisingly discovered that the correlation between the temperature of a given ferromagnetic body and its magnetic susceptibility can be utilized for temperature measurement. In particular, the invention provides for comprising a magnetic field source and a ferromagnetic body. The ferromagnetic body is magnetized by a magnetic field originating from the magnetic field source, resulting in an attractive force between the magnetic field source and the ferromagnetic body. The force sensor is configured to measure said attractive force between the magnetic field source and the ferromagnetic body. As mentioned above, the magnetic susceptibility and therefore the attractive force between the magnetic field source and the ferromagnetic body depends on the temperature of the ferromagnetic body (see FIG. 3). In the present invention, this causal relationship is exploited by pre-recording and storing reference data in a memory and then determining temperature information by evaluating measured force values ​​from the force sensor against said pre-recorded reference data.

[0016] In other words, the physical principle of this wireless thermometer is based on the fact that the force of attraction between a ferromagnetic body and a magnetic field source is a function of the ferromagnetic susceptibility, which is a function of temperature (see Figure 3). By calibrating the force / temperature reading of the transfer function, it is possible to determine the temperature of the ferromagnetic body, which will act as a temperature sensor, without wiring to electronics, and therefore wirelessly. Thanks to this wireless property, the ferromagnetic body can be placed in places where wiring is not possible or difficult, for example inside the consumable or inside the oven chamber.

[0017] Instead of ferromagnetic materials, ferrimagnetic materials can also be used. It should be noted that all features and preferred embodiments presented in relation to an embodiment using ferromagnetic materials can also be implemented using ferrimagnetic materials.

[0018] The quantitative correlation between the suction force and the temperature can be preferably established by performing a corresponding calibration. Alternatively, the quantitative correlation between the suction force and the temperature can be estimated based on the specific materials (type of magnetic field source and ferromagnetic body, distance between them, Curie constant, etc.) and formulas such as Curie's law and Curie-Weiss law. The correlation data between the suction force and the temperature can then be pre-recorded in the memory of the temperature measurement system. During use of the aerosol generating device, the control unit can then retrieve the measured force value from the force sensor and compare said value with the pre-recorded data. Based on this comparison, the control unit determines temperature information regarding the ferromagnetic body.

[0019] According to one embodiment of the invention, the pre-recorded correlation data may include only one threshold value for the attractive force and one associated value indicative of the temperature of the ferromagnetic body. In the above embodiment with a single pre-recorded threshold value for the attractive force, the control unit may compare the measured force value to the threshold value. If the measured force value is lower than the threshold value, the control unit determines that the target temperature (which may be, for example, a minimum temperature, an optimum temperature or a maximum temperature) has not yet been reached. If the measured force value is equal to or greater than the threshold value, the control unit determines that the target temperature has been achieved or exceeded. In this embodiment, the temperature information determined by the control unit is a binary parameter, with possible parameter values ​​being "target temperature achieved or exceeded" and "target temperature not achieved."

[0020] Preferably, the control unit is additionally configured to control the heating based on the obtained temperature information.

[0021] According to a preferred embodiment of the invention, the control unit of the temperature measurement system is configured to determine whether the ferromagnetic body has a temperature below and / or above its Curie temperature. At (or above) the Curie temperature, the magnetic susceptibility of the ferromagnetic body is very small (see FIG. 3). Therefore, based on the attraction between the magnetic field source and the ferromagnetic body, it can be determined with relatively high reliability whether the temperature of the ferromagnetic body is below or above the Curie temperature. In a particularly preferred embodiment, the ferromagnetic body exhibits a Curie temperature of particular interest in connection with the aerosol generating device, for example between 150° C. and 350° C., more preferably between 200° C. and 300° C., even more preferably between 230° C. and 270° C. Thereby, temperatures of particular relevance in the use of the aerosol generating device can be reliably determined, such as a minimum, optimum or maximum temperature required to generate a sufficient amount of aerosol. Preferably, the ferromagnetic body exhibits a Curie temperature corresponding to the maximum temperature, i.e. the highest recommended temperature for the aerosol generating material, ±20° C., preferably ±10° C. This is because the temperature dependence of magnetic susceptibility becomes more pronounced below the Curie temperature, making it easier to reliably determine temperatures within this temperature range of interest, i.e., below the maximum temperature of the aerosol-generating material.

[0022] According to a preferred embodiment, the pre-recorded data associates a plurality of force values ​​with corresponding temperatures of the ferromagnetic body, and the control unit is configured to determine the temperature of the ferromagnetic body. In this preferred embodiment, a specific correlation between the attraction force and the temperature can be established by performing a calibration that associates all discrete temperature values ​​within a predefined temperature range with corresponding force values ​​or force value ranges. For example, the resulting pre-recorded data can associate all temperatures between 0°C and 400°C with corresponding force value ranges in 0.1°C or 1°C steps. To avoid ambiguity, each force value can be associated with only one temperature value.

[0023] According to a preferred embodiment of the present invention, the force sensor includes a strain gauge, a load cell, or a system configured to convert force into displacement and measure the displacement. These types of force sensors are typically relatively small, so they can be easily implemented in a limited space in close proximity to the oven chamber. Furthermore, these sensors can be acquired with high sensitivity, so that reliable results can be ensured even with relatively small suction forces.

[0024] A preferred embodiment of the present invention is directed to an aerosol generating device comprising the temperature measurement system described above and an oven chamber having an oven wall.

[0025] According to a preferred embodiment of the aerosol generating device, the ferromagnetic body is provided on the inner surface of the oven wall, and the force sensor and the magnetic field source are provided on the outer surface of the oven wall facing the ferromagnetic body. This setup ensures a very reliable temperature measurement due to the short distance between the ferromagnetic body and the consumable inserted in the oven chamber. In other words, the temperature of the ferromagnetic body is very similar to the temperature of the aerosol generating material in the consumable.

[0026] According to another preferred embodiment of the present invention, the aerosol generating device comprises a consumable, preferably a tobacco stick, which is at least partially inserted into the oven chamber. Furthermore, a ferromagnetic body is provided inside the consumable in the oven chamber, and the force sensor and the magnetic field source are provided on the outer surface of the oven wall, facing the ferromagnetic body. In this arrangement, the ferromagnetic body is in direct contact with the aerosol-generating substance in the consumable. Thus, the temperature of the ferromagnetic body is essentially the same as the temperature of the aerosol-generating substance in the consumable. Preferably, the oven chamber and the consumable have a concentric cylindrical shape, and the ferromagnetic body is located on the cylindrical axis (of the consumable) within the consumable. This ensures a continuous distance between the ferromagnetic body and the magnetic field source, and therefore a reliable measurement.

[0027] According to a preferred embodiment of the present invention, the oven chamber of the aerosol generating device is made entirely of non-magnetic material or is provided with a non-magnetic window between the ferromagnetic material and the force sensor and the magnetic field source. This feature significantly improves the sensitivity of the attraction force measurement. In the context of the present invention, the term non-magnetic material refers to paramagnetic and / or diamagnetic materials.

[0028] Furthermore, the inventors have devised a method for measuring the temperature within an aerosol generating device, comprising the steps of providing a magnetic field source, a ferromagnetic body and a force sensor, measuring the force of attraction between the magnetic field source and the ferromagnetic body using the force sensor, and determining temperature information based on measured force values ​​obtained from the force sensor and pre-recorded data relating at least one force value to a value indicative of the temperature of the ferromagnetic body. For the reasons set out above, this measurement method is suitable for reliably measuring the temperature within an aerosol generating device.

[0029] The invention will now be described with reference to exemplary embodiments thereof. [Brief description of the drawings]

[0030] [Figure 1] 1 shows a schematic cross-sectional view of an aerosol generating device equipped with a temperature measurement system according to one embodiment of the present invention. [Diagram 2] 1 shows a schematic cross-sectional view of an aerosol generating device including another embodiment of the present invention. [Diagram 3] This is a qualitative plot of the magnetic susceptibility of a ferromagnetic material (or a ferrimagnetic material) versus temperature. [Figure 4] FIG. 2 is a detailed view of the magnetic field source, the non-magnetic window in the oven wall, the force sensor, and the magnetic field source of the temperature measurement system depicted in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate certain embodiments of the invention and, together with the description, serve to explain the principles of the invention. Other embodiments of the invention and many of the attendant advantages thereof will be readily apparent as the invention becomes better understood with reference to the following detailed description.

[0032] It will be appreciated that to facilitate a more abstract view of the embodiments, common and / or well-understood elements that may be useful or necessary in commercially feasible embodiments have not necessarily been depicted. Elements of the figures are not necessarily drawn to scale relative to each other. It will be further appreciated that, although certain acts and / or steps in method embodiments may be described or illustrated in a particular order, those skilled in the art will understand that no specificity regarding such order is actually required. It will also be understood that the terms and expressions used in this specification have ordinary meanings as consistent with such terms and expressions for their corresponding respective fields of inquiry and study, unless a specific meaning is otherwise defined herein.

[0033] FIG. 1 shows a schematic cross-sectional view of an aerosol generation device 1 according to one embodiment of the present invention, taken along the longitudinal direction of the aerosol generation device 1.

[0034] The aerosol generating device 1 contains an oven chamber with oven walls 5. The oven chamber is configured so that a user can place a consumable 6 therein. Preferably, the shape of the oven chamber and the consumable has an elongated cylindrical shape. However, the shape of the consumable 6 and the oven chamber should not be considered as limiting the concept of the present invention. The oven chamber comprises one or more oven walls 5. For example, the oven chamber may comprise a cylindrical side wall when the shape of the oven chamber is cylindrical as described above, or may comprise multiple side walls when the shape of the oven chamber is different from a cylindrical shape.

[0035] Although not shown in Fig. 1, the aerosol generating device 1 may include a heater for supplying heat to the oven chamber, thereby heating the aerosol generating material in the consumable 6 when inserted into the heating section. The heater is also located in the housing portion of the aerosol generating device 1. The heater is preferably a heater that supplies heat to the oven chamber based on resistive heating. However, the type of heating should not be considered as limiting the concept of the present invention.

[0036] The aerosol generating device 1 shown in Fig. 1 is equipped with a temperature measurement system according to an embodiment of the present invention. The temperature measurement system comprises a ferromagnetic body 4 provided on the inner surface of an oven wall 5 that defines the oven chamber, specifically on the inner surface of the lower base of the cylindrical oven chamber. The ferromagnetic body 4 is preferably disk-shaped.

[0037] An NdFeB grade N35 magnet is used as the magnetic field source 2. The magnet is also disk-shaped with a diameter of 10 mm and a thickness of 2 mm. The maximum tensile force generated between a single magnet and a polished thick flat steel plate is about 36 N. Alternatively, a grade N52 magnet can be used. At a distance of 0.5 cm, a tensile force of about 0.5 N is still generated by this magnet.

[0038] The force sensor 3 in this embodiment is a so-called Force Sensing Resistor (FSR). These sensors are robust polymer thick film (PTF) devices that exhibit a decrease in resistance with increasing force applied to the sensor surface. FSR devices are commonly available and the force sensing range is usually selected between about 0.2N and 20N. In this embodiment, an FSR 402 Short sensor from Interlink Electronics is used. From top to bottom, the force sensor comprises an adhesive 3a, an upper substrate 3b, a spacer adhesive 3c and a lower substrate 3d (see FIG. 4).

[0039] In this embodiment, the magnetic field source 2 is only glued to the lower substrate 3b of the force sensor 3. In other words, the magnet is free to move relative to the lower substrate 3b of the force sensor 3. The rest of the structure does not have to move, since it is the magnet that makes the small movements required to deform the lower substrate into the gaps of the spacer adhesive. This deformation causes a change in the resistance of the resistor printed on the lower substrate.

[0040] FIG. 2 shows a schematic cross-sectional view of an aerosol generating device 1 according to another embodiment of the present invention. One main difference with respect to the embodiment of FIG. 1 is the location of the ferromagnetic body 4. In this embodiment, the ferromagnetic body is provided in the consumable 6. This configuration brings the ferromagnetic body 4 into contact with the aerosol-generating material, thereby (theoretically) increasing the accuracy of the temperature measurement. However, as the distance between the ferromagnetic body 4 and the magnetic field source 2 increases, the resulting attraction force is also significantly limited, making it more difficult to accurately determine the temperature based on the measured force value. In addition, the embodiment of FIG. 2 also differs from the embodiment of FIG. 1 in that the magnetic field source 2 and the force sensor 3 are provided in the oven wall at the side of the oven chamber. [Explanation of symbols]

[0041] 1. Aerosol generator 2. Magnetic field source 3 Force Sensor 3a Adhesive 3b Top board 3c Spacer Adhesive 3d bottom board 4 Ferromagnetic or ferrimagnetic material 5 Oven walls 6 Consumables 7 Non-magnetic window 8. Memory 9. Control Unit

Claims

1. A temperature measurement system for an aerosol generator (1), comprising: a magnetic field source (2); a ferromagnetic or ferrimagnetic material (4); a force sensor (3) configured to measure an attractive force between the magnetic field source (2) and the ferromagnetic or ferrimagnetic material (4); a memory (8) storing pre-recorded data associating at least one force value with a value indicating the temperature of the ferromagnetic or ferrimagnetic material (4); a control unit (9) configured to determine temperature information based on the measured force value from the force sensor (3) and the pre-recorded data; A temperature measurement system comprising the above components.

2. The temperature measurement system according to claim 1, wherein the control unit (9) is configured to determine whether the ferromagnetic or ferrimagnetic material (4) has a temperature below and / or above the Curie temperature of the ferromagnetic or ferrimagnetic material (4). The temperature measurement system according to claim 1.

3. The pre-recorded data associates a plurality of force values with corresponding temperatures of the ferromagnetic or ferrimagnetic material (4), and the control unit (9) is configured to determine the temperature of the ferromagnetic or ferrimagnetic material (4). The temperature measurement system according to claim 1.

4. The temperature measurement system according to claim 1, wherein the force sensor (3) includes a strain gauge, a load cell, or a system configured to convert the force into displacement and measure the displacement.

5. An aerosol generator (1), comprising: the temperature measurement system according to any one of claims 1 to 4, and an oven chamber having an oven wall (5). An aerosol generator (1) comprising the above components.

6. The ferromagnetic or ferrimagnetic material (4) is provided on the inner surface of the oven wall (5), and the force sensor (3) and the magnetic field source (2) are provided on the outer surface of the oven wall (5) facing the ferromagnetic or ferrimagnetic material (4). The aerosol generator (1) according to claim 5.

7. A consumable (6), preferably a tobacco stick, at least partially inserted into the oven chamber, and the ferromagnetic or ferrimagnetic material (4) is provided inside the consumable (6) in the oven chamber, and the force sensor (3) and the magnetic field source (2) are provided on the outer surface of the oven wall (5) facing the ferromagnetic or ferrimagnetic material (4). The aerosol generator (1) according to claim 5.

8. The aerosol generator (1) according to claim 5, wherein the oven chamber is made entirely of a non-magnetic material or is provided with a non-magnetic window (7) between the ferromagnetic or ferrimagnetic body (4) and the force sensor (3) and the magnetic field source (2).

9. A method for measuring the temperature inside an aerosol generator (1), comprising: providing a magnetic field source (2), a ferromagnetic or ferrimagnetic body (4), and a force sensor (3); measuring, using the force sensor (3), the attractive force between the magnetic field source (2) and the ferromagnetic or ferrimagnetic body (4); determining temperature information based on the measured force value obtained from the force sensor (3) and pre-recorded data associating at least one force value with a value indicating the temperature of the ferromagnetic or ferrimagnetic body (4); A method comprising the steps of:

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