Insulation for aerosol generating devices

Abstract

The present invention relates to an aerosol-generating device comprising a cavity (10) for receiving an aerosol-generating article (12) including an aerosol-forming substrate (18). The cavity comprises a base (28). The base comprises at least one air opening (30). The device further comprises an induction heating device. The induction heating device comprises a susceptor device (14) and an induction coil (16). The induction heating device is disposed at least partially surrounding or forming the cavity. The device further comprises an insulating element (22). The insulating element is disposed between the susceptor device and the induction coil. The insulating element is sealingly attached to the base at the base of the cavity to prevent lateral airflow into the cavity.

Description

[Technical Field]

[0001] The present invention relates to an aerosol generating device. [Background technology]

[0002] It is known to provide aerosol-generating devices for generating inhalable vapors. Such devices may heat an aerosol-forming substrate to a temperature at which one or more components of the aerosol-forming substrate volatilize without burning the aerosol-forming substrate. The aerosol-forming substrate may be provided as part of an aerosol-generating article. The aerosol-generating article may have a rod shape for insertion of the aerosol-generating article into a cavity, such as a heating chamber, of the aerosol-generating device. A heating device may be disposed around the heating chamber to heat the aerosol-generating substrate when the aerosol-generating article is inserted into the heating chamber of the aerosol-generating device. The heating device may be configured as an induction heating device. For an induction heating device, the heating device may include an induction coil and a susceptor device. The susceptor device may be disposed to at least partially surround the heating chamber. The induction coil may be disposed surrounding the susceptor device. During operation, heating of the susceptor device may lead to an increase in the temperature of the induction coil in addition to heating the aerosol-generating article received in the heating chamber. The temperature rise of the induction coil may adversely affect the operation of the induction coil. Exemplarily, the electrical resistance of the induction coil may increase. Furthermore, heat may be lost, which may adversely affect the energy efficiency of the aerosol generating device.

[0003] It would be desirable to have an aerosol generating device with an induction heating device that has improved operating efficiency.It is also desirable to have an aerosol generating device with an induction heating device that has improved heating efficiency. Summary of the Invention

[0004] According to an embodiment of the present invention, there is provided an aerosol generating device comprising a cavity for receiving an aerosol-generating article comprising an aerosol-forming substrate. The cavity may comprise a base. The base comprises at least one air opening. The device further comprises an induction heating device. The induction heating device comprises a susceptor device and an induction coil. The induction heating device is disposed so as to at least partially surround or define the cavity. The device further comprises an insulating element. The insulating element is disposed between the susceptor device and the induction coil. The insulating element is sealingly attached to the base at the base of the cavity to prevent lateral airflow into the cavity.

[0005] Air openings disposed in the base allow axial airflow into the cavity. Airflow into the cavity is allowed in the axial direction, while lateral airflow into the cavity is prevented by the insulating element. The axial airflow may improve airflow into the aerosol-generating article, and the axial airflow may direct the airflow toward the upstream end face of the aerosol-generating article. To attach the insulating element to the base of the cavity, the insulating element may be glued to the base of the cavity. The upstream end face of the insulating element may be glued to the base of the cavity. Alternatively, the insulating element may extend outside the base of the cavity, whereby the inner surface of the insulating element may be attached to the base of the cavity, such as by gluing.

[0006] The susceptor unit may include one or more side walls of the susceptor unit. The one or more side walls of the susceptor unit may be permeable to allow lateral airflow to enter the cavity. The side walls of the susceptor unit may be formed from blade-shaped susceptors, and the lateral airflow may enter the cavity through gaps between the blade-shaped susceptors. The one or more side walls of the susceptor unit may include perforations or slits, whereby the lateral airflow may enter the cavity through the perforations or slits.

[0007] The insulating element may comprise one or more side walls of the insulating element. A gap may be provided between one or more side walls of the susceptor unit and one or more side walls of the insulating element. The gap may allow air to flow within the gap. An axial airflow may be provided within the gap. An axial path for the airflow may be provided by the gap to allow lateral airflow into the cavity at different axial positions. The gap may advantageously improve thermal insulation between the susceptor unit and the insulating element.

[0008] One or more side walls of the insulating element may be arranged to be substantially airtight in the lateral direction to prevent lateral air flow from exiting the cavity.

[0009] One or more side walls of the insulating element may coaxially surround one or more side walls of the susceptor unit. The one or more side walls of the insulating element may partially or completely form the side walls of the cavity, and the one or more side walls of the susceptor unit may be disposed adjacent to the one or more side walls of the insulating element toward the interior of the cavity.

[0010] One or more side walls of the susceptor unit may be permeable to lateral airflow to enter the cavity, and a gap may be provided between one or more side walls of the susceptor unit and one or more side walls of the insulating element. The permeable side walls of the susceptor unit may be airtight to prevent lateral airflow from exiting the cavity by the side walls of the insulating element.

[0011] The term "sealingly attached" may refer to an attachment between the insulating element and the base such that air flow is prevented in the area of the attachment. In other words, a seal may be provided by the attachment between the insulating element and the base.

[0012] The term "lateral" may refer to a direction perpendicular to the longitudinal axis of the aerosol generating device.

[0013] The air opening may have a longitudinal extension in the axial direction of the aerosol generating device. The air opening may have a circular cross section. The air opening may have an elongated, oval or rectangular cross section.

[0014] The insulating element may partially or completely form a sidewall of the cavity. The insulating element may partially or completely extend along the axial length of the cavity. The insulating element may directly abut the base of the cavity. The insulating element may be directly attached to the base of the cavity, thereby facilitating a sealed attachment between the insulating element and the base.

[0015] The aerosol generating device may include a housing, and the cavity may be located at a downstream end of the housing. The insulating element may be sealingly attached to the downstream end of the housing at the downstream end of the cavity to prevent lateral airflow into the cavity.

[0016] According to this embodiment, the insulating element preferably completely forms the side wall of the cavity or extends along the entire axial length of the cavity. The insulating element prevents lateral airflow into the cavity at the base of the cavity by sealingly attaching to the base of the cavity. Furthermore, according to this embodiment, the insulating element prevents lateral airflow into the cavity at the downstream end of the cavity by attaching between the insulating element and the housing of the aerosol generating device. In this embodiment, airflow into the cavity is preferably only possible through air openings arranged in the base of the cavity.

[0017] The insulating element may have a flat downstream end surface. The flat downstream end surface may aid in attachment between the insulating element and the aerosol generation device housing. The downstream end surface may abut directly against the aerosol generation device housing. The downstream end surface may be glued to the aerosol generation device housing.

[0018] The compartment in which the induction coil may be disposed may be hermetically sealed from the cavity by an insulating element at the downstream end of the cavity. The compartment in which the induction coil may be disposed may be disposed surrounding the cavity. This compartment may be referred to as a coil compartment. The coil compartment may partially or completely surround the cavity. The coil compartment may extend along the entire length of the cavity. The coil compartment may house an induction coil or multiple induction coils, as described in more detail below. The hermetic seal between the cavity and the coil compartment at the downstream end of the cavity by the insulating element prevents airflow between the coil compartment at the downstream end of the cavity and the cavity. Additionally, because the insulating element is sealingly attached to the base of the cavity and thereby prevents lateral airflow into the cavity at the base of the cavity, airflow between the cavity and the coil compartment may be prevented laterally along the entire length of the coil compartment.

[0019] The aerosol generating device may have an air inlet at the downstream end of the housing, and the air intake may be fluidly connected to the downstream end of the compartment in which the induction coil may be disposed. In other words, the aerosol generating device may have a downstream air intake connected to the coil compartment. The coil compartment may have an open upstream end. Air may be drawn from the downstream air intake through the coil compartment, through the coil compartment, and out the open upstream end of the coil compartment. The upstream open end of the coil compartment may be fluidly connected to an opening disposed at the base of the cavity.

[0020] Ambient air may be drawn into the coil section through the downstream air inlet. The air may then be drawn through the coil section, thereby cooling the induction coil disposed within the coil section. After passing through the coil section, the air may be drawn out of the coil section through the open upstream end of the coil section. After exiting the coil section, the air may be guided toward the base of the cavity and through the air openings into the air channel in a U-shape. The air may then enter the cavity and flow through the aerosol-generating article disposed within the cavity. Passage of the air through the coil section may preheat the air for optimized aerosol generation as the air flows through the aerosol-generating article received within the cavity.

[0021] In an alternative embodiment of the insulating element sealingly attached to the housing at the downstream end of the housing, a gap may be provided between the insulating element and the downstream end of the housing to allow lateral airflow into the cavity at the downstream end of the cavity. In this embodiment, airflow is allowed between the coil section and the cavity at the downstream end of the cavity. In other words, in this embodiment, a fluid connection is established between the coil section and the cavity at the downstream end of the cavity. Airflow is allowed adjacent to the downstream end of the insulating element. Airflow is allowed between the downstream end of the insulating element and the housing of the aerosol generating device.

[0022] The insulating element may have a convex downstream end surface, which may allow for smooth airflow between the coil section and the cavity without negatively impairing airflow.

[0023] The aerosol generating device may include an air inlet adjacent the upstream end of the cavity, the air inlet being in fluid communication with the upstream end of the compartment in which the induction coil may be disposed.

[0024] The air inlet may be fluidly connected to an air opening in the base of the cavity. Ambient air may flow through the air inlet adjacent the upstream end of the coil section toward the air opening in the base of the cavity. The air may then flow into the cavity and through the aerosol-generating article received in the cavity. Due to a gap provided between the downstream end of the insulating element and the housing of the aerosol generating device, air may flow from the cavity to the coil section through the gap. This air may flow through the coil section and out of the coil section at the open upstream end of the coil section. The open upstream end of the coil section may be fluidly connected to an airflow path between the air inlet and the air opening in the base of the cavity. Circular flow may be enabled between the cavity and the coil section by the gap between the insulating element and the housing and, on the other hand, by the open upstream end of the coil section. In this way, the induction coil disposed within the coil section may be cooled. At the same time, the air may be preheated to optimize aerosol generation.

[0025] The aerosol generating device may include a power source. The power source may be a direct current (DC) power source. The power source may be electrically connected to the first induction coil. In one embodiment, the power source is a DC power source having a DC supply voltage in the range of about 2.5 volts to about 4.5 volts and a DC supply current in the range of about 1 ampere to about 10 amperes (corresponding to a DC power supply in the range of about 2.5 watts to about 45 watts). The aerosol generating device may advantageously include a direct current to alternating current (DC / AC) inverter for converting the DC current provided by the DC power source into alternating current. The DC / AC converter may include a class D or class E power amplifier. The power source may be configured to provide the alternating current.

[0026] The power source may be a battery, such as a rechargeable lithium-ion battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging. The power source may have a capacity that allows for the storage of sufficient energy for one or more uses of the aerosol generating device. For example, the power source may have a capacity sufficient to allow continuous generation of aerosol for approximately six minutes, corresponding to the typical time it takes to smoke one conventional cigarette, or a multiple of six minutes. In another embodiment, the power source may have a capacity sufficient to allow for a predetermined number of puffs or for discontinuous activation.

[0027] The power source may be configured to operate at a high frequency. As used herein, the term "high frequency oscillating current" refers to an oscillating current having a frequency between 500 kilohertz and 30 megahertz. The high frequency oscillating current may have a frequency between about 1 megahertz and about 30 megahertz, preferably between about 1 megahertz and about 10 megahertz, and more preferably between about 5 megahertz and about 8 megahertz.

[0028] The induction heating device may be configured to generate heat by induction. The induction heating device comprises an induction coil and a susceptor device. A single induction coil may be provided. A single susceptor device may be provided. Preferably, more than a single induction coil is provided. A first induction coil and a second induction coil may be provided. Preferably, more than a single susceptor device is provided. Preferably, a first susceptor device and a second susceptor device are provided. The induction coil may surround the susceptor device. The first induction coil may surround the first susceptor device. The second induction coil may surround the second susceptor device. Alternatively, at least two induction coils may be provided surrounding the single susceptor device. If two or more susceptor devices are provided, it is preferred that an electrical insulating element be provided between the susceptor devices.

[0029] The susceptor device may include a susceptor. The susceptor device may include a plurality of susceptors. The susceptor device may include a blade-shaped susceptor. The blade-shaped susceptor may be arranged to surround a cavity. The blade-shaped susceptor may be arranged inside the cavity. The blade-shaped susceptor may be arranged to hold the aerosol-generating article when the aerosol-generating article is inserted into the cavity. The blade-shaped susceptor may have a flared downstream end to facilitate insertion of the aerosol-generating article into the blade-shaped susceptor. Air may flow into the cavity through air openings in the base of the cavity. The air may then enter the aerosol-generating article at the upstream end face of the aerosol-generating article. Alternatively or additionally, air may flow between the blade-shaped susceptor and a sidewall of the cavity, preferably formed by a thermal insulating element. The air may then pass through the gaps between the blade-shaped susceptors and into the aerosol-generating article. Uniform penetration of the aerosol-generating article by the air may be achieved in this way, thereby optimizing aerosol generation.

[0030] The aerosol generating device may include a magnetic flux concentrator. The magnetic flux concentrator may be made of a material having high magnetic permeability. The magnetic flux concentrator may be disposed surrounding the induction heating device. The magnetic flux concentrator may concentrate magnetic field lines within the magnetic flux concentrator, thereby increasing the heating effect of the susceptor device by the induction coil.

[0031] The aerosol generating device may include a controller. The controller may be electrically connected to the induction coil. The controller may be electrically connected to the first induction coil and to the second induction coil. The controller may be configured to control the current supplied to the induction coil and therefore the magnetic field strength generated by the induction coil.

[0032] The power supply and controller may be connected to the induction coils, preferably the first and second induction coils, and configured to provide alternating current to each of the induction coils independently of one another, such that, in use, each induction coil generates an alternating magnetic field. This means that the power supply and controller may be able to provide alternating current to the first induction coil alone, the second induction coil alone, or both induction coils simultaneously. Different heating profiles may be achieved in this manner. The heating profile may refer to the temperature of each induction coil. To heat to a high temperature, alternating current may be supplied to both induction coils simultaneously. To heat to a lower temperature or to heat only a portion of the aerosol-forming substrate of the aerosol-generating article, alternating current may be supplied only to the first induction coil. Thereafter, alternating current may be supplied only to the second induction coil.

[0033] A controller may be connected to the induction coil and the power source. The controller may be configured to control the supply of power from the power source to the induction coil. The controller may include a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application specific integrated circuit chip (ASIC) or other electronic circuit capable of providing control. The controller may include additional electronic components. The controller may be configured to regulate the current supply to the induction coil. Current may be supplied to one or both of the induction coils continuously after activation of the aerosol generating device, or may be supplied intermittently (such as with each puff).

[0034] The power supply and controller may be configured to independently vary the amplitude of the alternating current supplied to each of the first and second induction coils. In this arrangement, the strength of the magnetic field generated by the first and second induction coils may be independently varied by varying the amplitude of the current supplied to each coil. This may advantageously facilitate a variable heating effect. For example, the amplitude of the current provided to one or both of the coils may be increased during startup to reduce the start-up time of the aerosol generating device.

[0035] The first induction coil of the aerosol generating device may form part of a first circuit. The first circuit may be a resonant circuit. The first circuit may have a first resonant frequency. The first circuit may include a first capacitor. The second induction coil may form part of a second circuit. The second circuit may be a resonant circuit. The second circuit may have a second resonant frequency. The first resonant frequency may be different from the second resonant frequency. The first resonant frequency may be the same as the second resonant frequency. The second circuit may include a second capacitor. The resonant frequency of the resonant circuit depends on the inductance of each induction coil and the capacitance of each capacitor.

[0036] The cavity of the aerosol generating device may have an open end into which the aerosol-generating article is inserted. The cavity may have a closed end opposite the open end. The closed end may be the base of the cavity. The closed end may be closed except for the provision of an air opening disposed in the base. The base of the cavity may be flat. The base of the cavity may be circular. The base of the cavity may be disposed upstream of the cavity. The open end may be disposed downstream of the cavity. The longitudinal axis may extend between the open end and the closed end. The longitudinal axis of the cavity may be parallel to the longitudinal axis of the aerosol generating device.

[0037] The cavity may be configured as a heating chamber. The cavity may have a cylindrical shape. The cavity may have a hollow cylindrical shape. The cavity may have a circular cross section. The cavity may have an oval or rectangular cross section. The cavity may have a diameter corresponding to the diameter of the aerosol-generating article.

[0038] As used herein, the term "proximal" refers to the user end of the aerosol generating device or the mouth end of the aerosol generating device, and the term "distal" refers to the end opposite the proximal end. When referring to a cavity, the term "proximal" refers to the area closest to the open end of the cavity, and the term "distal" refers to the area closest to the closed end.

[0039] As used herein, the term "length" refers to the major dimension along the longitudinal axis of an aerosol-generating device, an aerosol-generating article, or a component of an aerosol-generating device or an aerosol-generating article.

[0040] As used herein, the term "width" refers to the major transverse dimension of an aerosol-generating device, an aerosol-generating article, or a component of an aerosol-generating device or article at a particular location along its length. The term "thickness" refers to the transverse dimension perpendicular to the width.

[0041] As used herein, the term "aerosol-forming substrate" relates to a substrate capable of releasing volatile compounds capable of forming an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate is part of an aerosol-generating article.

[0042] As used herein, the term "aerosol-generating article" refers to an article comprising an aerosol-forming substrate capable of emitting a volatile compound capable of forming an aerosol. For example, the aerosol-generating article may be an article that generates an aerosol that can be directly inhaled by a user sucking or puffing on a mouthpiece at the proximal or user end of the system. The aerosol-generating article may be disposable. An article comprising an aerosol-forming substrate containing tobacco is called a tobacco stick. The aerosol-generating article may be insertable into a cavity of an aerosol-generating device.

[0043] As used herein, the term "aerosol-generating device" refers to a device that interacts with an aerosol-generating article to generate an aerosol.

[0044] As used herein, the term "aerosol-generating system" refers to the combination of an aerosol-generating article as further described and illustrated herein with an aerosol-generating device as further described and illustrated herein. In the system, the aerosol-generating article and the aerosol-generating device cooperate to generate a respirable aerosol. The present invention may also relate to an aerosol-generating system.

[0045] As used herein, "susceptor device" means an electrically conductive element that heats when subjected to a changing magnetic field. This may be the result of eddy currents induced within the susceptor device, hysteresis losses, or both eddy currents and hysteresis losses. During use, the susceptor device is positioned in thermal contact or thermal proximity with an aerosol-forming substrate of an aerosol-generating article received within the cavity of the aerosol-generating device. In this manner, the aerosol-forming substrate is heated by the susceptor device, thereby forming an aerosol.

[0046] The susceptor device may preferably have a cylindrical shape structured by individual blade-shaped susceptors. The susceptor device may have a shape corresponding to the shape of the corresponding induction coil. The susceptor device may have a diameter smaller than the diameter of the corresponding induction coil so that the susceptor device can be disposed inside the induction coil.

[0047] The term "heating zone" refers to a portion of the length of the cavity that is at least partially surrounded by an induction coil such that a susceptor device positioned within or around the heating zone can be inductively heated by the induction coil. The heating zone may comprise a first heating zone and a second heating zone. The heating zone may be divided into a first heating zone and a second heating zone. The first heating zone may be surrounded by a first induction coil. The second heating zone may be surrounded by a second induction coil. Three or more heating zones may be provided. A plurality of heating zones may be provided. An induction coil may be provided for each heating zone. One or more induction coils may be movably disposed to surround the heating zone and may be configured for segmented heating of the heating zone.

[0048] As used herein, the term "coil" is interchangeable throughout with the terms "inductive coil" or "induction coil" or "inductor" or "inductor coil." A coil may be a driven (primary) coil connected to a power source.

[0049] The heating effect may be varied by independently controlling the first induction coil and the second induction coil. By providing the first induction coil and the second induction coil with different configurations, the heating effect may be varied because the magnetic field generated by each coil under the same applied current is different. For example, by forming the first induction coil and the second induction coil from different types of wire, the heating effect may be varied because the magnetic field generated by each coil under the same applied current is different. By independently controlling the first induction coil and the second induction coil and by providing different configurations for the first induction coil and the second induction coil, the heating effect may be varied because the magnetic field generated by each coil under the same applied current is different.

[0050] The induction coil(s) are each disposed at least partially around the heating zone. The induction coils may extend only partially around the periphery of the cavity in the region of the heating zone. The induction coils may extend around the entire periphery of the cavity in the region of the heating zone.

[0051] The induction coil(s) may be planar coils disposed around a portion of the perimeter of the cavity or around the entire perimeter of the cavity. As used herein, "planar coil" means a spirally wound coil with the axis of winding perpendicular to the surface on which the coil is placed. A planar coil may lie within a flat Euclidean plane. A planar coil may also lie on a curved surface. For example, a planar coil may be wound within a flat Euclidean plane and then bent to lie on a curved surface.

[0052] Advantageously, the induction coil(s) are helical. The induction coil may be helical and may be wound around a central space in which the cavity is located. The induction coil may be arranged around the entire periphery of the cavity.

[0053] The induction coil(s) may be helical and concentric. The first induction coil and the second induction coil may have different diameters. The first induction coil and the second induction coil may be helical and concentric and may have different diameters. In such embodiments, the smaller of the two coils may be at least partially positioned within the larger of the first induction coil and the second induction coil.

[0054] The windings of the first induction coil may be electrically isolated from the windings of the second induction coil.

[0055] The aerosol-generating device may further comprise one or more additional induction coils, for example, a third induction coil and a fourth induction coil, preferably associated with additional susceptors associated with different heating zones.

[0056] Advantageously, the first induction coil and the second induction coil may have different inductance values. The first induction coil may have a first inductance, and the second induction coil may have a second inductance that is smaller than the first inductance. This means that the magnetic fields generated by the first induction coil and the second induction coil will have different strengths for a given current. This may facilitate different heating effects by the first induction coil and the second induction coil while applying current of the same amplitude to both coils. This may reduce the control requirements of the aerosol generating device. When the first induction coil and the second induction coil are activated independently, the induction coil with the larger inductance may be activated at a different time than the induction coil with the smaller inductance. For example, the induction coil with the larger inductance may be activated during operation, such as during a puff, and the induction coil with the smaller inductance may be activated between operations, such as between puffs. Advantageously, this may facilitate maintaining a high temperature in the cavity between uses without requiring the same power as normal use. This "preheating" may reduce the time it takes for the cavity to return to a desired operating temperature once operation of the aerosol generating device is resumed. Alternatively, the first induction coil and the second induction coil may have the same inductance value.

[0057] The first induction coil and the second induction coil may be formed from the same type of wire. Advantageously, the first induction coil is formed from a first type of wire, and the second induction coil is formed from a second type of wire that is different from the first type of wire. For example, the wire compositions or cross sections may be different. In this manner, the inductances of the first induction coil and the second induction coil may be different even when the overall coil geometry is the same. This may allow the same or similar coil geometries to be used for the first induction coil and the second induction coil. This may facilitate a more compact arrangement.

[0058] The first type of wire may include a first wire material, and the second type of wire may include a second wire material that is different from the first wire material. The electrical properties of the first wire material may differ from the electrical properties of the second wire material. For example, the first type of wire may have a first resistivity, and the second type of wire may have a second resistivity that is different from the first resistivity.

[0059] Suitable materials for the induction coil(s) include copper, aluminum, silver, and steel. Preferably, the induction coil is formed from copper or aluminum.

[0060] When the first induction coil is formed from a first type of wire and the second induction coil is formed from a second type of wire that is different from the first type of wire, the first type of wire may have a different cross-section than the second type of wire. The first type of wire may have a first cross-section, and the second type of wire may have a second cross-section that is different from the first cross-section. For example, the first type of wire may have a first cross-sectional shape, and the second type of wire may have a second cross-sectional shape that is different from the first cross-sectional shape. The first type of wire may have a first thickness, and the second type of wire may have a second thickness that is different from the first thickness. The cross-sectional shapes and thicknesses of the first type of wire and the second type of wire may be different.

[0061] The susceptor device may be formed from any material that can be inductively heated to a temperature sufficient to aerosolize the aerosol-forming substrate. Suitable materials for the susceptor device include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Preferred susceptor devices include metal or carbon. Advantageously, the susceptor device may include or consist of ferromagnetic materials, such as ferritic iron, ferromagnetic steel, or stainless steel, ferromagnetic particles, and ferrite. Suitable susceptor devices may be or include aluminum. The susceptor device may include more than 5 percent ferromagnetic or paramagnetic material, preferably more than 20 percent ferromagnetic or paramagnetic material, and more preferably more than 50 percent or more than 90 percent ferromagnetic or paramagnetic material. Preferred susceptor devices may be heated to temperatures exceeding 250 degrees Celsius.

[0062] The susceptor device may be formed from a single layer of material, which may be a steel layer.

[0063] The susceptor device may include a non-metallic core having a metallic layer disposed thereon. For example, the susceptor device may include a ceramic core or a metallic track formed on the outer surface of the substrate.

[0064] The susceptor device may be formed from a layer of austenitic steel. One or more layers of stainless steel may be disposed on the layer of austenitic steel. For example, the susceptor device may be formed from a layer of austenitic steel with a layer of stainless steel on each of its upper and lower surfaces. The susceptor device may comprise a single susceptor material. The susceptor device may include a first susceptor material and a second susceptor material. The first susceptor material may be disposed in intimate physical contact with the second susceptor material. The first susceptor material and the second susceptor material may be in intimate contact to form a single, indestructible susceptor. In one particular embodiment, the first susceptor material is stainless steel and the second susceptor material is nickel. The susceptor device may have a two-layer structure. The susceptor device may be formed from a stainless steel layer and a nickel layer.

[0065] The intimate contact between the first susceptor material and the second susceptor material may be achieved by any suitable means. For example, the second susceptor material may be plated, deposited, coated, clad, or welded onto the first susceptor material. Preferred methods include electroplating, galvanizing, and cladding.

[0066] The second susceptor material may have a Curie temperature below 500 degrees Celsius. The first susceptor material may be primarily used to heat the susceptor when it is placed in an alternating electromagnetic field. Any suitable material may be used. For example, the first susceptor material may be aluminum or an iron-based material such as stainless steel. Preferably, the second susceptor material is primarily used to indicate when the susceptor reaches a specific temperature (the Curie temperature of the second susceptor material). The Curie temperature of the second susceptor material can be used to regulate the temperature of the entire susceptor during operation. Therefore, the Curie temperature of the second susceptor material should be below the ignition point of the aerosol-forming substrate. Suitable materials for the second susceptor material may include nickel and certain nickel alloys. The Curie temperature of the second susceptor material may be selected to be preferably less than 400°C, preferably less than 380°C, or even less than 360°C. The second susceptor material is preferably a magnetic material selected to have a Curie temperature substantially equal to the desired maximum heating temperature. That is, the Curie temperature of the second susceptor material is preferably approximately equal to the temperature to which the susceptor must be heated to generate an aerosol from the aerosol-forming substrate. The Curie temperature of the second susceptor material may be, for example, in the range of 200°C to 400°C, or in the range of 250°C to 360°C. In some embodiments, it may be preferable for the first susceptor material and the second susceptor material to be co-laminated. The co-laminarization may be formed by any suitable means. For example, strips of the first susceptor material may be welded or diffusion bonded to strips of the second susceptor material. Alternatively, a layer of the second susceptor material may be deposited or plated onto the strip of the first susceptor material.

[0067] The aerosol generating device is preferably portable. The aerosol generating device may have a size comparable to a conventional cigar or cigarette. The system may be an electrically operated smoking system. The system may be a handheld aerosol generating system. The aerosol generating device may have a total length of approximately 30 millimeters to approximately 150 millimeters. The aerosol generating device may have an outer diameter of approximately 5 millimeters to approximately 30 millimeters.

[0068] The housing may be elongated. The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composites containing one or more of these materials, or thermoplastics suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. Preferably, the material is light and not brittle.

[0069] The housing may include a mouthpiece. The mouthpiece may include at least one air inlet and at least one air outlet. The mouthpiece may include two or more air inlets. One or more of the air inlets may reduce the temperature of the aerosol before it is delivered to the user and may reduce the concentration of the aerosol before it is delivered to the user.

[0070] Alternatively, the mouthpiece may be provided as part of the aerosol-generating article.

[0071] As used herein, the term "mouthpiece" refers to the portion of an aerosol generating device that is placed into the user's mouth for direct inhalation of aerosol generated by the aerosol generating device from an aerosol-generating article received within a cavity of the housing.

[0072] The air intake port may be configured as a semi-open inlet. A semi-open inlet preferably allows air to enter the aerosol generating device. Air or liquid may be prevented from exiting the aerosol generating device through the semi-open inlet. The semi-open inlet may be, for example, a semi-permeable membrane that is permeable to air in only one direction but is airtight and liquid-tight in the opposite direction. The semi-open inlet may also be, for example, a one-way valve. A semi-open inlet preferably allows air to pass through the inlet only when certain conditions are met, such as a minimum pressure on the aerosol generating device or the amount of air passing through the valve or membrane.

[0073] Operation of the heating device may be triggered by a puff detection system. Alternatively, the heating device may be triggered by pressing an on / off button and maintained for the duration of the user's puff. The puff detection system may be provided as a sensor, which may be configured as an airflow sensor to measure airflow velocity. Airflow velocity is a parameter that characterizes the amount of air per time drawn by the user through the airflow path of the aerosol generating device. The onset of a puff may be detected by the airflow sensor when the airflow exceeds a predetermined threshold. Onset may also be detected when the user activates a button.

[0074] The sensor may also be configured as a pressure sensor for measuring the pressure of air inside the aerosol-generating device that is drawn through the airflow path of the device by the user during a puff. The sensor may be configured to measure the pressure difference or pressure drop between the pressure of the ambient air outside the aerosol-generating device and the pressure of the air drawn through the device by the user. The air pressure may be detected at the air inlet, the mouthpiece of the device, or a cavity (such as a heating chamber or any other passage or chamber within the aerosol-generating device through which air flows). When a user draws on the aerosol-generating device, a negative pressure or vacuum is created inside the device, and this negative pressure may be detected by the pressure sensor. The term "negative pressure" is understood as a pressure that is relatively lower than the pressure of the ambient air. In other words, when a user draws on the device, the air drawn through the device has a pressure that is lower than the pressure of the ambient air outside the device. The start of a puff may be detected by the pressure sensor when the pressure difference exceeds a predetermined threshold.

[0075] The aerosol generating device may include a user interface for activating the aerosol generating device, such as a button to initiate heating of the aerosol generating device, or a display that indicates the status of the aerosol generating device or the aerosol-forming substrate.

[0076] An aerosol generating system is a combination of an aerosol generating device and one or more aerosol-generating articles for use with the aerosol generating device. However, an aerosol generating system may also include additional components, such as an electrically operated aerosol generating device or a charging unit for recharging an on-board power supply in an electric aerosol generating device.

[0077] The aerosol-forming substrate may comprise nicotine. The nicotine-containing aerosol-forming substrate may be a nicotine salt matrix. The aerosol-forming substrate may comprise a plant-derived material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a tobacco-containing material comprising volatile tobacco flavour compounds that are released from the aerosol-forming substrate upon heating. Alternatively, the aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may comprise a homogenized plant-derived material. The aerosol-forming substrate may comprise a homogenized tobacco material. The homogenized tobacco material may be formed by agglomerating particulate tobacco. In a particularly preferred embodiment, the aerosol-forming substrate may comprise an assembly of a crimped sheet of homogenized tobacco material. As used herein, the term "crimped sheet" means a sheet having a plurality of substantially parallel ridges or corrugations.

[0078] The aerosol-forming substrate may include at least one aerosol former. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense and stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperatures of the system. Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (e.g., triethylene glycol, 1,3-butanediol, glycerin), esters of polyhydric alcohols (e.g., glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (e.g., dimethyl dodecanedioate, dimethyl tetradecanedioate). Preferred aerosol formers are polyhydric alcohols or mixtures thereof (e.g., triethylene glycol, 1,3-butanediol, etc.). Preferably, the aerosol former is glycerin. When present, the homogenized tobacco material may have an aerosol former content of 5 weight percent or more on a dry weight basis, and preferably has an aerosol former content of 5 weight percent to 30 weight percent on a dry weight basis. The aerosol-forming substrate may also include other additives and ingredients, such as flavorants.

[0079] In any of the above embodiments, the aerosol-generating article and the cavity of the aerosol-generating device may be arranged such that the aerosol-generating article is partially received within the cavity of the aerosol-generating device, or the aerosol-generating device and the cavity of the aerosol-generating article may be arranged such that the aerosol-generating article is completely received within the cavity of the aerosol-generating device.

[0080] The aerosol-generating article may be substantially cylindrical in shape. The aerosol-generating article may be substantially elongated. The aerosol-generating article may have a length and a circumference substantially perpendicular to the length. The aerosol-forming substrate may be provided as an aerosol-forming segment containing the aerosol-forming substrate. The aerosol-forming segment may be substantially cylindrical in shape. The aerosol-forming segment may be substantially elongated. The aerosol-forming segment may also have a length and a circumference substantially perpendicular to the length.

[0081] The aerosol-generating article may have an overall length of approximately 30 millimeters to approximately 100 millimeters. In one embodiment, the aerosol-generating article has an overall length of approximately 45 millimeters. The aerosol-generating article may have an outer diameter of approximately 5 millimeters to approximately 12 millimeters. In one embodiment, the aerosol-generating article may have an outer diameter of approximately 7.2 millimeters.

[0082] The aerosol-forming substrate may be provided as an aerosol-forming segment having a length of about 7 millimeters to about 15 millimeters. In one embodiment, the aerosol-forming segment may have a length of approximately 10 millimeters. Alternatively, the aerosol-forming segment may have a length of approximately 12 millimeters.

[0083] The aerosol-generation segment preferably has an outer diameter approximately equal to the outer diameter of the aerosol-generating article. The outer diameter of the aerosol-forming segment may be from approximately 5 millimeters to approximately 12 millimeters. In one embodiment, the aerosol-forming segment may have an outer diameter of approximately 7.2 millimeters.

[0084] The aerosol-generating article may include a filter plug. The filter plug may be located at the downstream end of the aerosol-generating article. The filter plug may be a cellulose acetate filter plug. The filter plug may be a hollow cellulose acetate filter plug. In one embodiment, the filter plug is approximately 7 millimeters long, but may have a length of approximately 5 millimeters to approximately 10 millimeters.

[0085] As used herein, the terms "upstream" and "downstream" are used to describe the relative location of a component or portion of a component of an aerosol generating device with respect to the direction in which a user draws on the aerosol generating device during use.

[0086] The aerosol-generating article may include an outer paper wrapper. Additionally, the aerosol-generating article may include a separation between the aerosol-forming substrate and the filter plug. The separation may be approximately 18 millimeters, but may also be in the range of approximately 5 millimeters to approximately 25 meters.

[0087] Features described with respect to one embodiment may equally apply to other embodiments of the invention.

[0088] The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0089] [Figure 1] FIG. 1 shows a cross-sectional view of an aerosol generating device according to the present invention. [Figure 2] FIG. 2 shows an exemplary diagram of an aerosol-generating device with an aerosol-generating article inserted and with the airflow indicated. [Figure 3] FIG. 3 shows a cross-sectional view of a further embodiment of an aerosol generating device. [Figure 4]FIG. 4 shows an exemplary diagram of the aerosol-generating article of FIG. 3 with an aerosol-generating article inserted and with the airflow indicated. DETAILED DESCRIPTION OF THE INVENTION

[0090] Figure 1 shows the proximal or downstream portion of an aerosol-generating device. The aerosol-generating device comprises a cavity 10 for insertion of an aerosol-generating article 12. The inserted aerosol-generating article 12 can be seen in Figures 2 and 4. The cavity 10 is configured as a heating chamber.

[0091] Disposed inside the cavity 10 is a susceptor device 14. The susceptor device 14 includes a plurality of susceptor blades. Each individual susceptor blade is flared at its downstream end for ease of insertion of the aerosol-generating article 12 into the cavity 10. The inner diameter of the susceptor device 14 corresponds to or is slightly smaller than the outer diameter of the aerosol-generating article 12. The aerosol-generating article 12 is held by the susceptor device 14 after insertion of the aerosol-generating article 12 into the cavity 10.

[0092] The susceptor device 14 is part of an induction heating device. The induction heating device includes an induction coil 16. The induction coil 16 is disposed so as to at least partially surround the cavity 10. The induction coil 16 surrounds the entire circumference of the cavity 10. The induction coil 16 is disposed so as to surround the susceptor device 14. The induction coil 16 surrounds a portion of the cavity 10 in which the substrate portion 18 of the aerosol-generating article 12 is received. A filter portion 20 of the aerosol-generating article 12 protrudes from the cavity 10 after the aerosol-generating article 12 is inserted into the cavity 10. A user draws on the filter portion 20.

[0093] Two or more induction coils 16 may be provided. Preferably, two induction coils 16, or three or more induction coils 16 are provided. The induction coils 16 may be part of an induction heating device. The induction coils 16 may be separately controllable to enable heating of separate heating zones within the cavity 10. Exemplarily, a first induction coil may be disposed to surround a downstream portion of the cavity 10 corresponding to a downstream heating zone, while a second induction coil may be disposed to surround an upstream portion of the cavity 10 corresponding to an upstream heating zone.

[0094] The aerosol generating device may include additional elements not shown in the figure, such as a controller for controlling the induction heating device. If the induction heating device includes more than one induction coil 16, the controller may be configured to separately control each individual coil. The aerosol generating device may include a power source, such as a battery. The controller may be configured to control the supply of electrical energy from the power source to the induction coil 16 or to each individual induction coil 16.

[0095] An insulating element 22 is disposed between the susceptor device 14 and the induction coil 16. The insulating element 22 forms a sidewall of the cavity 10. The insulating element 22 has an elongated extension. The insulating element 22 has a hollow cylindrical shape. The insulating element 22 is attached to a housing 24 of the aerosol generating device. The insulating element 22 is preferably attached to a downstream end 26 of the housing 24, as shown in FIG. 1 . Additionally, the insulating element 22 is attached to a base 28 of the cavity 10 at the downstream end of the cavity 10. One or more air openings 30 are disposed at the base 28 of the cavity 10.

[0096] The air opening 30 has an elongated extension parallel to the longitudinal axis of the aerosol generating device. The air opening 30 allows air to enter the cavity 10 at the upstream end 32 of the cavity 10. The insulating element 22 prevents air from entering the cavity 10 laterally. In other words, the insulating element 22 is disposed surrounding the cavity 10 such that air can enter the cavity 10 only at the upstream end 32 of the cavity 10 and can exit the cavity 10 only at the open downstream end of the cavity 10.

[0097] The induction coil 16 is disposed within a coil section 34. The coil section 34 is disposed surrounding an insulating element 22. The layered structure has a cavity 10 in the middle, in the middle. The insulating element 22 is disposed surrounding the cavity 10. The coil section 34 is disposed surrounding the insulating element 22. The aerosol generating device housing 24 is disposed surrounding the coil section 34.

[0098] An air inlet 36 is provided to allow ambient air to enter the coil section 34. The air inlet 36 is disposed at the downstream end 26 of the housing 24. Preferably, the air inlet 36 is disposed adjacent to the coil section 34. The air inlet 36 is provided between the outer periphery of the housing 24 and a portion of the downstream end 26 of the housing 24 connected to the insulating element 22. The air inlet 36 allows ambient air to be drawn into the coil section 34. Preferably, the air inlet 36 is not directly fluidly connected to the cavity 10. The upstream end of the coil section 34 is open. Air drawn into the coil section 34 through the air inlet 36 exits the coil section 34 at the open upstream end of the coil section 34. After exiting the coil section 34, the air flows in a U-shape toward an air opening 30 disposed in the base 28 of the cavity 10. The air then enters the cavity 10 at the upstream end 32 of the cavity 10. The air flowing through the coil section 34 before entering the cavity 10 is utilized to cool the induction coil 16 disposed within the coil section 34 .

[0099] In Figure 1, a resilient sealing element 38 is shown at the downstream end of the cavity 10. The resilient sealing element 38 is disposed surrounding the downstream end of the cavity 10. The resilient sealing element 38 has a circular shape. The resilient sealing element 38 has a funnel shape that facilitates insertion of the aerosol-generating article 12. After insertion, the resilient sealing element 38 applies pressure to the aerosol-generating article 12 to hold the aerosol-generating article 12 in place. The resilient sealing element 38 is air-impermeable to prevent air from escaping from the cavity 10 except through the aerosol-generating article 12.

[0100] 2 shows a diagram of an aerosol-generating device in which an aerosol-generating article 12 is inserted into a cavity 10. A substrate portion 18 of the aerosol-generating article 12 is received within the cavity 10. A filter portion 20 of the aerosol-generating article 12 may protrude from the cavity 10 for a user to inhale the aerosol-generating article 12.

[0101] 2, the airflow is shown in addition to the inserted aerosol-generating article 12. Air flows into the aerosol-generating device through an air inlet 36. More than one air inlet 36 may be provided. The air flows through the coil section 34. After exiting the coil section 34, the air flows into the cavity 10 through air openings 30 disposed in the base 28 of the cavity 10. The air then flows into the aerosol-generating article 12 through gaps provided between the individual susceptor blades.

[0102] 3 shows a further embodiment in which the downstream end of the insulating element 22 is not attached to the downstream end of the aerosol generation device housing 24. Rather, a gap is provided between the downstream end of the insulating element 22 and the aerosol generation device housing 24. Additionally, in the embodiment shown in FIG. 3, the air inlet 36 is positioned differently. The air inlet 36 is positioned within the sidewall of the aerosol generation device housing 24. In other words, the air inlet 36 is positioned on the outer periphery of the aerosol generation device housing 24. The air inlet 36 is disposed adjacent to the upstream end of the cavity 10.

[0103] As shown in FIG. 4 , when air is drawn into the cavity 10 through the air inlet 36, it is drawn directly from the air inlet 36 toward the air openings 30 disposed in the base 28 of the cavity 10. When air is drawn into the cavity 10, in contrast to the embodiment shown in FIGS. 1 and 2 , it is possible for the air not to simply exit the cavity 10 through the inserted aerosol-generating article 12. Instead, the air is drawn out of the cavity 10, through the gap between the insulating element 22 and the housing 24, and into the coil section 34. The air drawn into the coil section 34 may exit the coil section 34 through the open upstream end thereof, similar to the embodiment shown in FIGS. 1 and 2 . The air exiting the coil section 34 is drawn back into the cavity 10 through the air openings 30 disposed in the base 28 of the cavity 10. In the embodiment shown in FIG. 3 , air may circulate between the cavity 10 and the coil section 34, which has various advantages. The induction coil 16 is cooled. Additionally or alternatively, the air is preheated before entering or re-entering the cavity 10.

Claims

1. An aerosol generating device, comprising: a cavity for receiving an aerosol-generating article comprising an aerosol-forming substrate, said cavity comprising a base, said base comprising at least one air opening; an induction heating device comprising a susceptor device and an induction coil, the induction heating device disposed to at least partially surround or form the cavity; an insulating element disposed between the susceptor device and the induction coil and attached to the base of the cavity so as to prevent lateral airflow into the cavity at the base in a direction perpendicular to the longitudinal axis of the aerosol-generating device; An aerosol generating device wherein one or more side walls of said susceptor device are permeable to lateral airflow into said cavity.

2. 2. The aerosol generating device of claim 1, wherein the aerosol generating device comprises a housing, the cavity is disposed within a downstream end of the housing, and the insulating element is sealingly attached to the downstream end of the housing to prevent lateral airflow into the cavity at the downstream end of the cavity.

3. 3. The aerosol generating device of claim 2, wherein the insulating element has a downstream end surface, the downstream end surface being flat.

4. 4. The aerosol generating device according to claim 2 or 3, wherein the aerosol generating device comprises a compartment in which the induction coil is disposed, the compartment being hermetically sealed from the cavity by the insulating element at the downstream end of the cavity.

5. 5. The aerosol generating device of claim 4, wherein the aerosol generating device has an air inlet at the downstream end of the housing, the air inlet being fluidly connected to the downstream end of the compartment in which the induction coil is disposed.

6. 2. The aerosol generating device of claim 1, wherein the aerosol generating device comprises a housing, the cavity is disposed within a downstream end of the housing, and a gap is provided between the insulating element and the downstream end of the housing to allow lateral airflow into the cavity at the downstream end of the cavity.

7. 7. The aerosol generating device of claim 6, wherein the insulating element has a convex downstream end surface.

8. 8. An aerosol generating device according to claim 1, wherein the insulating element at least partially forms a side wall of the cavity.

9. 9. An aerosol generating device according to any one of claims 1 to 8, wherein the insulating element extends partly or completely along the length of the cavity.

10. 10. An aerosol generating device according to any one of claims 1 to 9, wherein the insulating element is glued to the base of the cavity.

11. 11. The aerosol generating device according to claim 1, wherein a gap is provided between the one or more side walls of the susceptor device and a side wall of the thermal insulating element.

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