An aerosol generating system comprising a cartridge having an internal air flow passage

Abstract

The present invention provides a cartridge (200) for use in an electrically heated aerosol-generating system, the electrically heated aerosol-generating system comprising an aerosol-generating device (100), the cartridge being configured to be used with the device, wherein the device (100) comprises a device housing (101); an inductor coil (110) located within the device housing; and a power source (102), the power source being connected to the inductor coil and being configured to provide a high-frequency oscillating current to the inductor coil (110); the cartridge (200) comprising a cartridge housing (204) containing an aerosol-generating substrate, the housing (204) having an inner surface (212) surrounding an inner passage (216) through which air can flow; and a susceptor element (210) positioned to heat the aerosol-generating substrate.

Description

[0001] The present application is a divisional application of the Chinese patent application with international application number PCT / EP2015 / 060728, Chinese application number 201580023629.0, application date May 14, 2015, and name “Aerosol generating system including a cartridge having an internal air flow channel”. Technical Field

[0002] The present disclosure relates to an aerosol-generating system that operates by heating an aerosol-forming substrate. In particular the present invention relates to an aerosol-generating system comprising a device portion containing a power source and a replaceable cartridge portion comprising a consumable aerosol-forming substrate. Background Art

[0003] One type of aerosol-generating system is an electronic cigarette. Electronic cigarettes typically use a liquid aerosol-forming substrate that is vaporized to form an aerosol. Electronic cigarettes typically use a power source, a liquid storage portion for holding a supply of the aerosol-forming substrate, and an atomizer.

[0004] The liquid aerosol-forming substrate is depleted during use and therefore needs to be replenished. The most common way to supply refills of the liquid aerosol-forming substrate is a cartridge of the cartomiser type. The cartomiser cartridge comprises a supply of the liquid substrate and an atomiser, which is usually in the form of an electrically operated resistive heater wound around a capillary material immersed in the aerosol-forming substrate. Replacing the atomiser cartridge as a single unit has the benefit of being convenient for the user and avoiding the need for the user to have to clean or otherwise maintain the atomiser.

[0005] However, it would be desirable to be able to provide a system that allows refills of aerosol-forming substrate to be produced at a lower cost and more durable than currently available atomizer cartridges, while still being easy and convenient for consumers to use. It would also be desirable to provide a system that does not require welded joints and allows for easily cleanable sealing devices. Summary of the invention

[0006] In a first aspect, the present invention provides a cartridge for use in an electrically heated aerosol-generating system, the electrically heated aerosol-generating system comprising an aerosol-generating device, the cartridge being configured for use with the device, wherein the device comprises a device housing; an inductor coil located within the device housing; and a power source connected to the inductor coil and configured to provide a high-frequency oscillating current to the inductor coil; the cartridge comprising a cartridge housing containing an aerosol-forming substrate, the housing having an interior surface surrounding an interior passage through which air can flow; and a susceptor element positioned to heat the aerosol-forming substrate.

[0007] Advantageously, at least a portion of the interior surface of the housing is fluid permeable. As used herein, a "fluid permeable" element means an element that allows liquid or gas to penetrate therethrough. The housing may have a plurality of openings formed therein to allow fluid to penetrate therethrough. Specifically, the housing allows aerosol-forming substrate to penetrate therethrough in both the gas phase or the gas phase and the liquid phase.

[0008] In operation, a high frequency oscillating current is passed through the flat spiral inductor coil to generate an alternating magnetic field which induces a voltage in the susceptor element. The induced voltage causes a current to flow in the susceptor element and the current causes Joule heating of the susceptor, which in turn heats the aerosol-forming substrate. If the susceptor element is ferromagnetic, the hysteresis losses in the susceptor element also generate heat. The vaporized aerosol-forming substrate may pass through the susceptor element and subsequently cool to form an aerosol that is delivered to the user.

[0009] The advantage of this arrangement using induction heating is that there is no need to form electrical contact between the tube and the device. And the heating element (in this case, the susceptor element) does not need to be electrically connected to any other parts, and does not need solder or other bonding elements. In addition, the coil is provided as a part of the device, so that a simple, cheap and durable tube can be constructed. The tube is typically a disposable product produced in a quantity far greater than the device operating with them. Therefore reducing the cost of the tube (even if it requires a more expensive device) can lead to significant cost savings for manufacturers and consumers.

[0010] As used herein, a high frequency oscillating current means an oscillating current having a frequency between 500 kHz and 30 MHz.The high frequency oscillating current may have a frequency between 1 and 30 MHz, preferably between 1 and 10 MHz and more preferably between 5 and 7 MHz.

[0011] The provision of an internal passage in the cartridge for airflow allows a compact system. It also allows the system to be made symmetrical and balanced, which is advantageous when the system is a handheld system. The internal passage for airflow also minimizes heat loss from the device and allows the housing of the device and cartridge to be easily maintained at a comfortable temperature. The vaporized aerosol-forming substrate in the airflow can be cooled in the internal passage and form aerosol.

[0012] The aerosol-forming substrate may be held within the annular space surrounding the internal passage.The cartridge may have a generally cylindrical shape and may have any desired cross-section, such as circular, hexagonal, octagonal or decagonal.

[0013] As used herein, a "susceptor element" means an electrically conductive element that heats when subjected to a changing magnetic field. This may be the result of eddy currents and / or hysteresis losses induced in the susceptor element. Possible materials for the susceptor element include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, and virtually any other electrically conductive element. Advantageously, the susceptor element is a ferrite element. The material and geometry of the susceptor element may be selected to provide the desired resistance and heat generation. The susceptor element may comprise, for example, a mesh, a flat spiral coil, an inner coil, a fiber, or a fabric.

[0014] Advantageously, the susceptor element is in contact with the aerosol-forming substrate.The susceptor element may form part or all of the interior surface.The susceptor element may advantageously be fluid permeable.

[0015] The susceptor element may be provided as a sheet extending across an opening in the cartridge housing.The susceptor element may extend around an inner periphery or an outer periphery of the cartridge housing.

[0016] Alternatively, the susceptor element may comprise a capillary wick extending across the internal passage of the cartridge.The wick may comprise a plurality of fibres.

[0017] Advantageously, the susceptor element has a relative permeability between 1 and 40,000. When it is desired that most of the heating be by eddy currents, a lower permeability material may be used, and when a hysteresis effect is desired a higher permeability material may be used. Preferably, the material has a relative permeability between 500 and 40,000. This provides efficient heating.

[0018] The material of the susceptor element may be chosen due to its Curie temperature. Above its Curie temperature the material is no longer ferromagnetic and therefore heating due to hysteresis effects no longer occurs. In case the susceptor element is made of a single material, the Curie temperature may correspond to the maximum temperature that the susceptor element should have (that is, the Curie temperature is the same as the temperature to which the susceptor element should be heated or deviates from this maximum temperature by about 1-3%). This reduces the possibility of rapid overheating.

[0019] If the susceptor element is made of more than one material, the materials of the susceptor element may be optimized with respect to further aspects. For example, the materials may be selected such that a first material of the susceptor element may have a Curie temperature that is higher than the maximum temperature to which the susceptor element should be heated. For example, this first material of the susceptor element may then be optimized with respect to maximum heat generation and transfer to the aerosol-forming substrate on the one hand to provide efficient heating of the susceptor. However, the susceptor element may then additionally include a second material having a Curie temperature corresponding to the maximum temperature to which the susceptor should be heated, and once the susceptor element reaches this Curie temperature, the magnetic properties of the susceptor element change overall. This change may be detected and transmitted to a microcontroller, which then interrupts the generation of alternating current until the temperature cools again to below the Curie temperature, whereby alternating current generation may be resumed.

[0020] The majority of the cartridge housing is preferably a rigid housing comprising a liquid impermeable material. "Rigid housing" when used herein means a self-supporting housing.

[0021] The aerosol-forming substrate is a substrate that can release volatile compounds that can form an aerosol. The volatile compounds can be released by heating the aerosol-forming substrate. The aerosol-forming substrate can be solid or liquid, or include solid and liquid components.

[0022] The smoke-forming substrate may include a plant material. The smoke-forming substrate may include tobacco. The smoke-forming substrate may include a tobacco-containing material containing volatile tobacco flavor compounds, which are released from the smoke-forming substrate when heated. The smoke-forming substrate may alternatively include a material that does not contain tobacco. The smoke-forming substrate may include a homogenized plant material. The smoke-forming substrate may include a homogenized tobacco material. The smoke-forming substrate may include at least one aerosol former. The smoke-forming agent is any suitable known compound or a mixture of compounds that is convenient for forming dense and stable smoke in use and is substantially resistant to thermal degradation at the operating temperature of the system. Suitable aerosol formers are well known in the art and include, but are not limited to: polyols, such as triethylene glycol, 1,3-butylene glycol and glycerol; esters of polyols, such as glycerol mono-, di- or triacetate; and fatty acid esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanoate. Preferred aerosol formers are polyhydroxy alcohols or mixtures thereof, such as triethylene glycol, 1,3-butylene glycol and most preferably glycerol. The aerosol-forming substrate may include other additives and ingredients, such as flavourants.

[0023] The aerosol matrix can be adsorbed, coated, impregnated or otherwise loaded on a carrier or support. In one example, the aerosol matrix is ​​a liquid matrix held in a capillary material. The capillary material can have a fibrous or spongy structure. The capillary material preferably includes a capillary bundle. For example, the capillary material can include a plurality of fibers or lines or other fine-pore tubes. The fiber or line can be aligned substantially to transfer the liquid to the heater. Alternatively, the capillary material can include a spongy or foamy material. The structure of the capillary material forms a plurality of small holes or tubes, and liquid can be transported through the small holes or tubes by capillary action. The capillary material can include any suitable material or a combination of materials. The example of a suitable material is a sponge or foam material, a ceramic or graphite-based material in the form of a fiber or sintered powder, a foamed metal or a plastic material, for example, a fibrous material made by spinning or extruding a fiber, such as cellulose acetate, polyester or bonded polyolefin, polyethylene, terylene or polypropylene fiber, nylon fiber or ceramic. The capillary material may have any suitable capillary action and porosity for use with different liquid physical properties. Liquids have physical properties, including but not limited to viscosity, surface tension, density, thermal conductivity, boiling point and vapor pressure, which allow the liquid to be transported through the capillary material by capillary action. The capillary material may be configured to deliver the aerosol-forming substrate to the susceptor element. The capillary material may extend into a gap in the susceptor element.

[0024] The susceptor element may be provided on a wall of the cartridge housing, the wall being configured to be positioned adjacent the inductor coil when the cartridge housing is engaged with the device housing. In use, it is advantageous to have the susceptor element close to the inductor coil in order to maximise the voltage induced in the susceptor element.

[0025] In a second aspect, an electrically heated aerosol-generating system is provided, comprising an aerosol-generating device and a cartridge according to the first aspect, the device comprising:

[0026] Device housing;

[0027] an inductor coil located within the device housing; and

[0028] A power source is connected to the inductor coil and is configured to provide a high frequency oscillating current to the inductor coil; wherein, in use, the magnetic field generated by the inductor coil causes heat to be generated in the susceptor material within the cartridge.

[0029] When the cartridge housing is engaged with the device housing, the air flow channel may be disposed between the inductor coil and the susceptor element.The vaporized aerosol-forming substrate may be entrained in air flowing in the air flow channel, which is subsequently cooled to form an aerosol.

[0030] When the device housing is engaged with the tube housing, the device housing may define a cavity for receiving at least a portion of the tube, wherein the inductor coil is disposed in the cavity, around the cavity, or adjacent to the cavity. When the tube is received in the cavity, the inductor coil may be disposed outside the tube. When the tube is received in the cavity, the inductor coil may surround the tube. The inductor coil may be shaped to be consistent with the inner surface of the cavity.

[0031] Alternatively, the inductor coil may be within the cavity when the cartridge is received in the cavity. In some embodiments, the inductor coil is within the interior passage when the cartridge housing is engaged with the device housing.

[0032] The device housing may include a body and a mouthpiece portion. The cavity may be in the body and the mouthpiece portion may have an outlet through which smoke generated by the system may be drawn into the user's mouth. The inductor coil may be in the mouthpiece portion or in the body.

[0033] Alternatively, the mouthpiece portion may be provided as part of the cartridge. When used herein, the term mouthpiece portion means a portion of a device or cartridge that is placed in the user's mouth to directly inhale the aerosol generated by the aerosol-generating system. The aerosol is delivered to the user's mouth through the mouthpiece.

[0034] The device may include a single inductor coil or multiple inductor coils. One or more inductor coils may be spiral coils or flat spiral coils. The inductor coil may be wound around a ferrite core. When used herein, "flat spiral coil" means a coil that is a generally planar coil, wherein the winding axis of the coil is perpendicular to the surface on which the coil is located. However, when used herein, the term "flat spiral coil" encompasses planar coils as well as flat spiral coils that are shaped to conform to a curved surface. The use of flat spiral coils allows the design of compact devices with a simple design that is durable and inexpensive to manufacture. The coil can be kept within the device housing and does not need to be exposed to the generated fumes so that deposits and possible corrosion on the coil can be prevented. The use of flat spiral coils also allows a simple interface between the device and the cartridge, allowing a simple and inexpensive cartridge design. The flat spiral inductor may have any desired shape within the plane of the coil. For example, the flat spiral coil may have a circular shape or may have a generally oblong shape.

[0035] The inductor coil may have a shape that matches the shape of the susceptor element.The coil may have a diameter between 5 mm and 10 mm.

[0036] The system may also include a circuit connected to the inductor coil and a power source. The circuit may include a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application specific integrated chip (ASIC) or other electronic circuit capable of providing control. The circuit may also include electronic components. The circuit may be configured to regulate the current supplied to the coil. Current may be continuously supplied to the inductor coil after starting the system or may be supplied intermittently on a puff-by-puff basis. The circuit may advantageously include a DC / AC converter, which may include a Class D or Class E power amplifier.

[0037] The system advantageously includes a power source in the body of the housing, typically a battery, such as a lithium iron phosphate battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may need to be recharged and may have a capacity that allows storage of enough energy for one or more smoking experiences. For example, the power source may have enough capacity to allow continuous generation of aerosol for a period of about six minutes, corresponding to the typical time spent smoking a conventional cigarette, or for a period of multiple six minutes. In another example, the power source may have enough capacity to allow a predetermined number of puffs or intermittent activation of the inductor coil.

[0038] The system may be an electrically operated smoking system. The system may be a handheld aerosol generating system. The aerosol generating system may have a size comparable to a conventional cigar or cigarette. The smoking system may have an overall length of between about 30 mm and about 150 mm. The smoking system may have an outer diameter of between about 5 mm and about 30 mm.

[0039] Features described in relation to one aspect may be applicable to other aspects of the disclosure. In particular, advantageous or optional features described in relation to the first aspect of the disclosure may be applicable to the second aspect of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Embodiments of a system according to the present disclosure will now be described in detail, by way of example only, with reference to the accompanying drawings, in which:

[0041] Figure 1 is a schematic diagram of a first embodiment of an aerosol generating system using a flat spiral inductor coil;

[0042] Figure 2 show Figure 1 The tube;

[0043] Figure 3 show Figure 1 The inductor coil;

[0044] Figure 4 is a schematic diagram of a second embodiment;

[0045] Figure 5 is a schematic diagram of a third embodiment;

[0046] Figure 6 for Figure 5 An end view of a cylinder;

[0047] Figure 7 exhibit Figure 5 The inductor coil and magnetic core;

[0048] Fig. 8A is a first example of a drive circuit for generating a high frequency signal for an inductor coil; and

[0049] Figure 8B is a second example of a driving circuit for generating a high frequency signal for an inductor coil. DETAILED DESCRIPTION

[0050] The embodiments shown in the figures all rely on induction heating. Induction heating works by placing the conductive article to be heated in a time-varying magnetic field. Eddy currents are induced in the conductive article. If the conductive article is electrically insulated, the eddy currents are consumed by the Joule heating of the conductive article. In a smoke-forming system that operates by heating the smoke-forming substrate, the smoke-forming substrate is typically not sufficiently conductive itself and is thus inductively heated in this way. Therefore, in the embodiments shown in the figures, the susceptor element is used as the heated conductive article and the smoke-forming substrate is then heated by the susceptor element through heat conduction, convection and / or radiation. If a ferromagnetic susceptor element is used, heat is also generated by hysteresis losses when the magnetic domains switch in the susceptor element.

[0051] The described embodiments all use an inductor coil to generate a time varying magnetic field. The inductor coil is designed so that it does not experience significant Joule heating. In contrast the susceptor element is designed so that there is significant Joule heating of the susceptor.

[0052] Figure 1 is a schematic diagram of an aerosol generating system according to a first embodiment. The system comprises a device 100 and a cartridge 200. The device comprises a main housing 101 containing a lithium iron phosphate battery 102 and control electronics 104. The main housing 101 also defines a cavity 112 in which the cartridge 200 is received. The device also comprises a mouthpiece portion 120 having an outlet 124. The mouthpiece portion is connected to the main housing 101 by a hinged connection in this example, but any type of connection may be used, such as a snap fit or a screw fit. When the mouthpiece portion is in a closed position, as shown in FIG. Figure 1 As shown in FIG. 1 , the air inlet 122 is defined between the mouthpiece portion 120 and the main body 101 .

[0053] Inside the device housing, in the side wall of cavity 112, is a flat spiral inductor coil 110. Coil 110 is formed by stamping or cutting a spiral coil from copper sheet. Figure 31. If the device housing has a generally circular cross-section, the coil 110 can be shaped to conform to the curvilinear shape of the device housing. The coils 110 are disposed on either side of the cavity and generate a magnetic field that extends within the cavity.

[0054] The cartridge 200 comprises a cartridge housing 204 which holds a capillary material and which is filled with a liquid aerosol-forming substrate. Figure 1 The cartridge 200 has Figure 2 The cartridge housing 204 is primarily liquid impermeable. The interior surface 212 of the cartridge 200 (i.e., the surface surrounding the interior passage 216) includes a fluid permeable susceptor element 210 (a ferrite mesh in this example). Figure 1 As shown, the ferrite mesh may line the entire interior surface of the cartridge or only a portion of the interior surface of the cartridge. The aerosol-forming substrate may form a meniscus in the interstices of the mesh. Another option for the susceptor is a graphite fabric with an open mesh structure.

[0055] When the cartridge 200 is engaged with the device and received in the cavity 112, the susceptor element 210 is positioned within the magnetic field generated by the flat helical coil 110. The cartridge 200 may include a keying feature to ensure that it is not incorrectly inserted into the device.

[0056] In use, the user draws on the mouthpiece portion 120 to draw air through the central channel of the tube through the air inlet 164, through the susceptor element 262, into the mouthpiece portion 120 and out of the outlet 124 into the user's mouth. When the suction is detected, the control electronics supplies a high-frequency oscillating current to the coil 110. This generates an oscillating magnetic field. The oscillating magnetic field passes through the susceptor element, inducing eddy currents in the susceptor element. The susceptor element heats up due to Joule heating and due to hysteresis losses in the susceptor element, reaching a temperature sufficient to evaporate the aerosol-forming substrate near the susceptor element. The vaporized aerosol-forming substrate is entrained in the air flowing from the air inlet to the air outlet through the internal passage 216, and is cooled before entering the user's mouth to form aerosol in the mouthpiece portion. After the suction is detected, the control electronics supplies an oscillating current to the coil for a predetermined duration (five seconds in this example), and then cuts off the current until a new suction is detected.

[0057] It can be seen that the cartridge has a simple and durable design which can be manufactured cheaply compared to the atomizer cartridges available on the market. The use of a hollow cartridge allows the overall length of the system to be shorter, as the steam cools within the hollow space defined by the cartridge.

[0058] Figure 4 The second embodiment is described. Figure 4 Only the front end of the system is shown in the , because it can be used with Figure 1The same battery and control electronics shown in FIG, including the puff detection mechanism. Figure 4 The cartridge 200 shown in FIG. Figure 1 However, Figure 4 The device has a different configuration that includes a flat spiral inductor coil 132 on a support blade 136 that extends into the central passage 216 of the barrel to generate an oscillating magnetic field proximate to the susceptor element 210. Figure 4 The operation of the embodiment is Figure 1 The same.

[0059] Figure 5 The third embodiment is described. Figure 5 Only the front end of the system is shown in the , because you can use Figure 1 The same battery and control electronics shown in FIG, including the puff detection mechanism.

[0060] Figure 5 The device is similar to Figure 1 The device of claim 1, wherein the housing 150 of the device defines a cavity within which the cartridge 250 is received. The device also includes a mouthpiece portion 120 having an outlet 124. The mouthpiece portion is formed by Figure 1 The hinged connection shown is connected to the main housing 101. An air inlet 154 is defined in the body 150. At the bottom of the cavity there is a helical coil 152 surrounding a C-shaped ferrite core 153. The C-shaped core is oriented so that the magnetic field generated by the coil 152 extends into the cavity. Figure 7 The core and coil assembly are shown separately, and the magnetic field pattern is shown with dotted lines.

[0061] Figure 5 The tube is displayed in Figure 6 The cartridge housing 250 has the following Figure 1 and Figure 2 256 therethrough. The aerosol-forming substrate is held in an annular space around the central passage and, as before, may be held in a capillary element within the housing 250. A capillary wick 252 is provided at one end of the barrel, spanning the central passage 256. The capillary wick 252 is formed of ferrite fibre and acts both as a core for the aerosol-forming substrate and as a susceptor which is inductively heated by the coil 152.

[0062] In use, an aerosol-forming substrate is drawn into the ferrite core 252. When a puff is detected, the coil 152 is activated and an oscillating magnetic field is generated. The changing magnetic flux across the core induces eddy currents and hysteresis losses in the core, causing it to heat up, vaporizing the aerosol-forming substrate within the core. The vaporized aerosol-forming substrate is entrained in the air drawn through the system from the air inlet 154 to the outlet 124 by the smoker's puff on the mouthpiece portion. The air flows through the internal passage 256, which acts as an aerosol-forming chamber, cooling the air and vaporizing it as it passes through the outlet 124.

[0063] The described embodiments may all be driven by substantially the same electronic circuit 104 . Fig. 8A A first example of a circuit for providing a high frequency oscillating current to an inductor coil using a class E power amplifier is described. Fig. 8A As can be seen, the circuit includes a class E power amplifier, which includes a transistor switch 1100 including a field effect transistor (FET) 1110, such as a MOSFET, a transistor switch power supply circuit indicated by arrow 1120 that supplies a switching signal (gate-source voltage) to the FET 1110, and an LC load network 1130 including a parallel capacitor C1 and a series connection of a capacitor C2 and an inductor L2. A DC power supply including a battery 101 includes a choke L1 and supplies a DC supply voltage. Fig. 8A Also shown is an ohmic resistance R representing a total resistive load 1140, which is the ohmic resistance R of the inductor coil labeled L2. Coil and the ohmic resistance R of the sensor element Load The sum of .

[0064] Due to the small number of components, the volume of the power electronics can be kept small. This extremely small volume of the power electronics is possible because the inductor L2 of the LC load network 1130 is used directly as an inductor for inductive coupling to the susceptor element, and this small volume allows the overall size of the entire induction heating device to be kept small.

[0065] Although the general operating principles of Class-E power amplifiers are known and described in detail in the already mentioned article "Class-E RF Power Amplifiers" by Nathan O. Sokal, published in the bimonthly magazine QEX, January / February 2001, pages 9-20, of the American Radio Relay League (ARRL), Newington, CT, USA, some general principles will be explained below.

[0066] Let us assume that the transistor switch supply circuit 1120 supplies a switching voltage (gate-source voltage of the FET) having a rectangular distribution to the FET 1110. As long as the FET 1321 is conducting (in the "on" state), it essentially constitutes a short circuit (low resistance) and the entire current flows through the choke L1 and the FET 1110. When the FET 1110 is not conducting (in the "off" state), the entire current flows into the LC load network because the FET 1110 essentially represents an open circuit (high resistance). Switching the transistor between these two states inverts the supplied DC voltage and DC current into an AC voltage and AC current.

[0067] In order to efficiently heat the susceptor element, the supplied DC power is transmitted to the inductor L2 as much as possible in the form of AC power and then transmitted to the susceptor element inductively coupled to the inductor L2. The power consumed in the susceptor element (eddy current losses, hysteresis losses) generates heat in the susceptor element, as further described above. In other words, the power consumption in the FET 1110 must be minimized while maximizing the power consumption in the susceptor element.

[0068] The power dissipated in the FET 1110 during one cycle of the AC voltage / current is the product of the transistor voltage and current at each moment during the cycle of the AC voltage / current, integrated over the period and averaged over the cycle. Since the FET 1110 must withstand high voltages during a portion of the cycle and conduct high currents during a portion of the cycle, the simultaneous presence of high voltages and high currents must be avoided because this will result in significant power dissipation in the FET 1110. In the "on" state of the FET 1110, the transistor voltage is nearly zero when a high current is flowing through the FET. In the "off" state of the FET 1110, the transistor voltage is high, but the current through the FET 1110 is nearly zero.

[0069] The switching transistor inevitably also extends for some time periods of this cycle. However, the high voltage-current product that represents high power losses in the FET 1110 can be avoided by the following additional measures. First, the rise of the transistor voltage is delayed until the current through the transistor has dropped to zero. Second, the transistor voltage returns to zero before the current through the transistor begins to rise. This is achieved by a series-connected load network 1130 including parallel capacitors C1 and C2 and inductor L2, which is the network between the FET 1110 and the load 1140. Third, the transistor voltage is actually zero when turned on (for a bijunction transistor "BJT", it is the saturation bias voltage V o). The turned-on transistor does not discharge the charged shunt capacitor C1, thus avoiding dissipation of the energy stored in the shunt transistor. Fourth, the slope of the transistor voltage is zero during the on-time. Then, the current injected into the turned-on transistor by the load network rises smoothly at a controllable and moderate rate, resulting in low power dissipation, while the transistor conductance accumulates from zero during the conduction transition. As a result, the transistor voltage and current are not high at the same time. The switching inversions of voltage and current are time-shifted from each other. The values ​​of L1, C1 and C2 can be selected to maximize the efficient dissipation of power in the sensor element.

[0070] Although class E power amplifiers are preferred for most systems according to the present disclosure, other circuit configurations can be used. Figure 8B A second example of a circuit for providing a high frequency oscillating current to an inductor coil using a class D power amplifier is described. Figure 8B The circuit comprises a battery 101 connected to two transistors 1210, 1212. Two switching elements 1220, 1222 are provided for switching the two transistors 1210, 1212 on and off. The switches are controlled at high frequency in a way to ensure that one of the two transistors 1210, 1212 is switched off while the other of the two transistors is switched on. The inductor coil is again indicated by L2 and the combined ohmic resistance of the coil and the susceptor element is indicated by R. The values ​​of C1 and C2 may be selected to maximize the effective loss of power in the susceptor element.

[0071] The susceptor element may be made of a material or combination of materials having a Curie temperature close to the desired temperature to which the susceptor element should be heated. Once the temperature of the susceptor element exceeds the Curie temperature, the material changes its ferromagnetic properties to paramagnetic properties. As a result, the energy consumption in the susceptor element is significantly reduced, since the hysteresis losses of materials having paramagnetic properties are much lower than those of materials having ferromagnetic properties. This reduced power consumption in the susceptor element can be detected, and, for example, the generation of alternating current by the DC / AC converter can then be interrupted until the susceptor element has cooled below the Curie temperature again and has recovered its ferromagnetic properties. The generation of alternating current by the DC / AC inverter can then be resumed again.

[0072] Other cartridge designs including susceptor elements according to the present disclosure may now be envisioned by those skilled in the art. For example, the cartridge may include a mouthpiece portion and may have any desired shape. In addition, the coil and susceptor arrangement according to the present disclosure may be used in other types of systems other than those already described, such as humidifiers, air fresheners, and other aerosol-generating systems.

[0073] The exemplary embodiments described above are illustrative and not limiting. In view of the above exemplary embodiments, those of ordinary skill in the art will now appreciate other embodiments consistent with the above exemplary embodiments.

Claims

1. An electric heating aerosol generating system, the electric heating aerosol generating system comprising an aerosol generating device and a cartridge, the aerosol generating device comprising: a device housing defining a cavity for receiving at least a portion of the cartridge; a flat spiral inductor coil located within the housing of the device; and a power source connected to the inductor coil and configured to provide a high frequency oscillating current to the inductor coil, wherein, in use, a magnetic field generated by the inductor coil causes heat to be generated in a susceptor material within the cartridge; The cartridge comprises: a cartridge housing containing an aerosol-forming substrate, the cartridge housing having an interior surface surrounding an interior passage through which air can flow; and A susceptor element is positioned to heat the aerosol-forming substrate.

2. The electric heating aerosol generating system according to claim 1, wherein: The aerosol-forming substrate is retained within an annular space surrounding the internal passageway.

3. The electric heating aerosol generating system according to claim 1, wherein: The inductor coil is positioned around the cavity and is external to the cartridge when the cartridge is received in the cavity.

4. The electric heating aerosol generating system according to claim 1, wherein: The cartridge comprises a capillary material and wherein the aerosol-forming substrate is a liquid substrate held in the capillary material.

5. An electric heating aerosol generating system, the electric heating aerosol generating system comprising an aerosol generating device and a cartridge, the aerosol generating device comprising: a device housing defining a cavity for receiving at least a portion of the cartridge; an inductor coil located within the housing of the device; and a power source connected to the inductor coil and configured to provide a high frequency oscillating current to the inductor coil, wherein, in use, a magnetic field generated by the inductor coil causes heat to be generated in a susceptor material within the cartridge; The cartridge comprises: a cartridge housing containing an aerosol-forming substrate, the cartridge housing having an interior surface surrounding an interior passage through which air can flow; and a susceptor element positioned to heat the aerosol-forming substrate; Wherein, the device shell includes a main body and a cigarette holder part.

6. The electric heating aerosol generating system according to claim 5, wherein: The cavity receives at least a portion of the cartridge when the device housing is engaged with the cartridge housing, and wherein the inductor coil is positioned within, around, or near the cavity.

7. The electrically heated smoke generating system according to claim 6, wherein: The cavity is located in the main body, and the mouthpiece portion has an outlet, through which the smoke generated by the electric heating smoke generating system can be attracted into the user's mouth.

8. The electric heating aerosol generating system according to claim 5, wherein: The inductor coil is located in the body.

9. The electrically heated smoke generating system according to claim 5, wherein: The aerosol-forming substrate is retained in an annular space surrounding the internal passageway.

10. A cartridge for use in an electrically heated aerosol-generating system, the electrically heated aerosol-generating system comprising an aerosol-generating device, the cartridge being configured to be used with the aerosol-generating device, wherein: The aerosol-generating device comprises: a device housing defining a cavity for receiving at least a portion of the cartridge; an inductor coil located within the device housing, the inductor coil surrounding the cavity and located outside the cartridge when the cartridge is received in the cavity; and a power source connected to the inductor coil and configured to provide a high-frequency oscillating current to the inductor coil; The cartridge comprises a cartridge housing containing a liquid aerosol-forming substrate retained in a capillary material, the cartridge housing having an interior surface surrounding an interior passage through which air can flow; the cartridge further comprising a susceptor element positioned to heat the liquid aerosol-forming substrate.

11. The cartridge according to claim 10, wherein The liquid aerosol-forming substrate is retained in an annular space surrounding the internal passageway.

12. The cartridge according to claim 10, wherein The susceptor element forms part or all of the interior surface.

13. An electrically heated aerosol generating system, comprising an aerosol generating device and a cartridge according to any one of claims 10 to 12, wherein the aerosol generating device comprises: a device housing defining a cavity for receiving at least a portion of the cartridge; an inductor coil located within the device housing, the inductor coil surrounding the cavity and located external to the cartridge when the cartridge is received in the cavity; and a power source connected to the inductor coil and configured to provide a high frequency oscillating current to the inductor coil; Wherein, in use, a magnetic field generated by the inductor coil causes heat to be generated in a susceptor material within the cartridge.

14. A cartridge for use in an electrically heated aerosol-generating system, the electrically heated aerosol-generating system comprising an aerosol-generating device, the cartridge being configured to be used with the aerosol-generating device, wherein: The aerosol-generating device comprises: a device housing defining a cavity for receiving at least a portion of the cartridge; an inductor coil located within the device housing; and a power source connected to the inductor coil and configured to provide a high-frequency oscillating current to the inductor coil; The cartridge comprises: a cartridge housing containing an aerosol-forming substrate, the cartridge housing having an interior surface surrounding an interior passage through which air can flow; and a susceptor element positioned to heat the aerosol-forming substrate; Therein, the susceptor element comprises a material having a Curie temperature corresponding to a maximum temperature to which the susceptor element should be heated.

15. The cartridge according to claim 14, wherein The susceptor element comprises a first material having a Curie temperature higher than a maximum temperature to which the susceptor element should be heated, and the material having a Curie temperature corresponding to the maximum temperature to which the susceptor element should be heated is a second material.

16. The cartridge of claim 14, wherein The aerosol-forming substrate is retained in an annular space surrounding the internal passageway.

17. An electrically heated aerosol generating system, comprising an aerosol generating device and a cartridge according to any one of claims 14 to 16, wherein the aerosol generating device comprises: a device housing defining a cavity for receiving at least a portion of the cartridge; an inductor coil located within the housing of the device; and a power source connected to the inductor coil and configured to provide a high frequency oscillating current to the inductor coil; Wherein, in use, a magnetic field generated by the inductor coil causes heat to be generated in a susceptor material within the cartridge.

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