Heater assembly including insulation layer

Abstract

A heater assembly (100) for an aerosol generator, comprising: a heating element (110) for vaporizing a liquid aerosol forming substrate; a porous body (130) for transporting the liquid aerosol forming substrate to the heating element; and an insulating layer (120) having a lower thermal conductivity than the porous body (130), wherein the insulating layer (120) is positioned between and in contact with the porous body (130) and the heating element (110), and the insulating layer (120) is configured to reduce heat transfer from the heating element (110) to the porous body (130), the porous body (130) includes a porous ceramic body or a porous glass body, and the heating element forms a film across the insulating layer.

Description

[Technical Field]

[0001] This disclosure relates to heater assemblies for aerosol generators. In particular, though not exclusive, this disclosure relates to heater assemblies for handheld, electrically operated aerosol generators for heating an aerosol-forming substrate to generate an aerosol and delivering the aerosol into a user's mouth. This disclosure further relates to a device comprising a heater assembly and a cartridge comprising a heater assembly. [Background technology]

[0002] Aerosol generating systems that heat a liquid aerosol-forming substrate to generate an aerosol to be delivered to a user are generally known in the prior art. These systems typically comprise an aerosol generator, a storage unit attached to the device, or a replaceable cartridge. The storage unit contains a liquid aerosol-forming substrate that can release volatile compounds when heated. The device also typically includes a heater for heating the liquid aerosol-forming substrate. In known aerosol generating systems, the heater comprises a resistance heating element wound around a wick that supplies the liquid aerosol-forming substrate to a heating element. The aerosol generator or cartridge also comprises a mouthpiece. When negative pressure is applied to the mouthpiece, an electric current flows through the heating element, causing the heating element to be heated by resistance heating or Joule heating, and consequently the liquid aerosol-forming substrate supplied by the wick to be heated. This causes volatile compounds to be released from the liquid aerosol-forming substrate, which then cool to form an aerosol. The aerosol is then drawn into the user's mouth through the mouthpiece.

[0003] Such known aerosol generation systems have many drawbacks. For example, it is difficult to maintain consistent manufacturing tolerances during production, which can lead to inconsistent vapor generation and flavor development. Inconsistent manufacturing tolerances can also affect heat conduction from the heating element to the core, reducing the energy efficiency of such devices. Furthermore, "dry heating" or "dry fumes" can occur when the liquid aerosol-forming substrate supplied to the heating element is heated in an insufficient state, which can result in an unsatisfactory user experience.

[0004] One known aerosol generating system comprises a ceramic body and a heating element, to which power is supplied through electrical contacts. Liquid is supplied from a liquid reservoir to the heating element through pores in the ceramic body. In this known aerosol generating system, thermal inefficiency arises from energy loss in the heating element. In this system, energy is lost from the heating element to the ceramic body and to the liquid within the ceramic body. These energy losses increase the energy required during use. These energy losses also reduce the amount of time the device can be used before the device's battery needs to be recharged or replaced.

[0005] It is desirable to provide heater assemblies that are more energy-efficient. It is also desirable to provide heater assemblies that increase the amount of power the device can use before the battery needs to be recharged or replaced. [Overview of the Initiative]

[0006] According to one embodiment of the present disclosure, a heater assembly for an aerosol generator is provided. The heater assembly may include a heating element for vaporizing a liquid aerosol-forming substrate. The heater assembly may include a porous body for transporting the liquid aerosol-forming substrate to the heating element. The heater assembly may include an insulating layer. The insulating layer may have a lower thermal conductivity than the porous body. The insulating layer may be positioned between the porous body and the heating element. The insulating layer may be in contact with the porous body and the heating element. The insulating layer may be configured to reduce heat transfer from the heating element to the porous body. The porous body may include a porous ceramic body or a porous glass body.

[0007] According to one embodiment of the present disclosure, a heater assembly for an aerosol generator is provided. The heater assembly comprises a heating element for vaporizing a liquid aerosol-forming substrate. The heater assembly comprises a porous body for transporting the liquid aerosol-forming substrate to the heating element. The heater assembly comprises an insulating layer having a lower thermal conductivity than the porous body. The insulating layer is positioned between the porous body and the heating element, respectively. The insulating layer is in contact with both the porous body and the heating element. The insulating layer is configured to reduce heat transfer from the heating element to the porous body. The porous body includes a porous ceramic body or a porous glass body.

[0008] In this configuration, heat loss from the heating element to the porous body and the liquid within the porous body is reduced. This provides a more efficient heater assembly that allows users to increase the amount and number of uses of the device before the device power source, such as batteries, is depleted. The inventors estimated that in known devices, about one-third of the energy from the heating element is lost through conduction through the porous body and the liquid within the porous body. The remaining two-thirds are used to generate aerosols by heating the liquid aerosol-forming substrate. In the configuration described herein, these energy losses are reduced. Specifically, the insulating layer reduces heat propagation or conduction from the heating element to or through the porous body. This reduction in conduction allows heat to be concentrated on the heated surface of the porous body, minimizing heat dissipation and increasing the heating efficiency of the heater assembly.

[0009] As used herein, the term "aerosol generator" refers to a device that interacts with a liquid aerosol-forming substrate in order to generate an aerosol.

[0010] As used herein, the terms “cartridge” and “aerosol generating cartridge” refer to components that interact with a liquid aerosol generating apparatus for generating an aerosol. An aerosol generating cartridge contains, or is configured to contain, a liquid aerosol-forming substrate.

[0011] As used herein, the term “liquid aerosol-forming substrate” refers to a liquid substrate having the ability to release volatile compounds that can form aerosols. Such volatile compounds may be released by heating the aerosol-forming substrate.

[0012] As used herein, the term “porous” refers to a component having multiple pores. At least some of the pores are open pores. At least some of the pores are interconnected so that a liquid can pass through the porous component.

[0013] As used herein, the term “porous material” refers to a component having multiple pores. At least some of the pores are open pores. At least some of the pores are interconnected so that a liquid can pass through the porous component. The porous material is configured to contain a liquid within its multiple pores.

[0014] As used herein, “heating element” refers to a component that transfers thermal energy to a liquid aerosol-forming substrate.

[0015] As used herein, the term “thermal insulation” refers to a property that reduces or limits heat transfer. A more thermally insulating component transfers less heat than a less thermally insulating component, via conduction, convection, or radiation.

[0016] The heating element may form a film over the heat insulation layer.

[0017] The heat insulation layer may contain a heat insulating material. The heat insulating material may have a lower thermal conductivity than the porous body. The heat insulating material may have a higher porosity than the porous body. This has the advantage of providing a heat insulation layer that is particularly effective in reducing energy loss while being easy to manufacture.

[0018] The heat insulation layer may contain a material having a thermal conductivity of less than 40 watts per meter kelvin. This has the advantage of providing a heat insulation layer effective in reducing energy loss through the porous body. The heat insulation layer may contain a material having a thermal conductivity of less than 10 watts per meter kelvin. This has the advantage of providing a heat insulation layer particularly effective in reducing energy loss through the porous body.

[0019] The heat insulation layer may extend entirely between the porous body and the heating element. This has the advantage of more effectively providing a barrier between the heating element and the porous body, and is therefore particularly effective in reducing energy loss through the porous body.

[0020] The heat insulation layer may contain one or more of alumina, zirconia, zirconia containing magnesium oxide, glass ceramic, quartz, and porous polymer. The porous polymer may be polyimide.

[0021] The heat insulation layer may contain alumina having a thermal conductivity of 20 to 40 watts per meter kelvin. The heat insulation layer may contain materials such as zirconia, glass ceramic, and quartz, with or without magnesium oxide, having a thermal conductivity of less than 10 watts per meter kelvin. The use of alumina, zirconia with or without magnesium oxide, glass ceramic, and quartz is advantageous because these materials are compatible with manufacturing processes involving sintering, and thus a heater assembly having a heat insulation layer of one of these materials can be manufactured more easily.

[0022] The insulation layer may have a thickness of 0.1 mm to 2 mm. Insulation layers of this thickness are particularly suitable for reducing energy loss from the heating element to the porous ceramic body. Preferably, the insulation layer has a thickness of 0.5 mm to 1.5 mm. Insulation layers of this thickness are even more suitable for reducing energy loss from the heating element to the porous ceramic body.

[0023] Porous bodies may include porous ceramic bodies or porous glass bodies. Porous bodies may include porous materials having open pores. Multiple open pores may be interconnected to provide fluid pathways for aerosol-generating liquids passing through the porous body. Porous bodies may include materials that do not chemically interact with the liquid aerosol-forming substrate. Porous materials may have a porosity of 20 percent to 80 percent. Porous bodies may have flat or curved surfaces. Porous bodies may have geometric shapes. Porous bodies may be cubic or cubic in shape, or disk or cylindrical in shape, or any combination thereof. Porous bodies may include or consist of materials having low thermal conductivity. Porous bodies may include or consist of non-conductive materials. Porous bodies may include polymer materials or ceramic materials. Porous bodies may include cotton. The porous material may include, but is not limited to, porous ceramics such as Al2O3, ZrO2, Si3N4, SiC, Ti3AlC2, BN, AlN, SiO2, MgO, mica, diatomaceous earth, silicates, borides, glass, or any combination of these materials. The porous material may also contain aluminum nitride or silicon carbide. Aluminum nitride and silicon carbide typically have relatively high thermal conductivity of about 100–200 watts / meter-Kelvin. In sintered form, aluminum nitride and silicon carbide can have thermal conductivity of less than 100 watts / meter-Kelvin.

[0024] The porous body may be composed of a monolithic material or a hybrid material. The porous body may be composed of different parts that are attached to each other. These different parts may contain or consist of different materials and may have different forms, shapes, and properties. The porous body may have a thickness such that heat loss through conduction to the liquid storage section is negligible. The porous body may have a thickness that depends on the thermal properties of the material it is made from and the liquid it contains. The porous body may have a thickness of 0.5 mm to 10 mm. The porous body may contain an electrical insulating material.

[0025] The heating element may be placed on an insulating layer. The heating element may be attached to an insulating layer. The heating element may be attached to a porous body by an insulating layer. The heating element may be attached to a porous body having an insulating layer between the heating element and the porous body. The heating element may comprise a conductive material, or may consist of a conductive material. The heating element may contain, or consist of, metals such as stainless steel, Ni-Cr alloy, NiCrAlY alloy, FeCrAl alloy (e.g., "Kanthal"), FeCrAlY alloy, Fe3Al alloy, Ni3Al alloy, NiAl alloy, and CuNi alloy. The heating element may contain, or consist of, electroceramics such as MoSi2, doped SiC, indium tin oxide (ITO), lanthanum-doped strontium titanate (SLT), yttrium-doped strontium titanate, or any combination of these materials. The heating element may contain an impermeable material. When electricity is supplied, the heating element may generate heat by Joule heating.

[0026] The heating element may be deposited or patterned by thick-film techniques such as screen printing, inkjet printing, aerosol jet printing, or LDS (laser direct structuring). The heating element may also be deposited or patterned by thin-film techniques such as PVD (physical deposition, e.g., evaporation, sputtering) or CVD (chemical deposition). The resistance of the heating element at room temperature may be 0.5 ohms to 1.5 ohms, 0.7 ohms to 1.3 ohms, or preferably 1 ohm.

[0027] The heating element may be a porous heating element.

[0028] The heating element may extend to cover a portion of the heating surface of the insulation layer. The heating element may extend to cover a substantial portion of the heating surface of the insulation layer. The heating element may extend to cover at least half of the heating surface of the insulation layer. Preferably, the heating element extends to cover at least two-thirds of the heating surface of the insulation layer. More preferably, the heating element extends to cover at least three-quarters of the heating surface of the insulation layer. More preferably, the heating element extends to cover all of the heating surface of the insulation layer.

[0029] A template can be added to a heating element material that is removed by sintering to form a porous structure, thereby enhancing liquid vaporization. The heating element may have a microstructure indicating that it was manufactured using a template, and the template is removed by sintering to form a porous structure.

[0030] The heating element may be placed on at least one surface of the porous body. The heating element may cover at least one surface of the porous body. The heating element may enclose the porous body. The porous heating element may be planar or may have any preferred shape.

[0031] In known meandering heating elements, the onset of failure in the meandering heater track is accompanied by an increase in local resistance. In meandering heating elements, the increase in local resistance leads to increased power dissipation, further increasing resistance until failure occurs, i.e., forming a positive feedback loop. A porous layer avoids this effect by allowing the current flow to be redistributed and avoiding the areas of increased resistance. Porous heating elements extending over an insulating layer are particularly advantageous.

[0032] Heater assemblies having an insulating layer combined with a porous heating element are particularly advantageous. Such combinations are especially advantageous when the porous heating element extends to cover the entire heating surface of the porous body and thereby cover the insulating layer. In these cases, low thermal conductivity to the porous body can be achieved, which reduces heat loss while maintaining consistent heating of the aerosol-forming substrate. In contrast, when track-type heaters, such as serpentine or electrically parallel track heating elements, are combined with an insulating layer, a higher in-plane thermal conductivity of the insulating layer is required to allow heat to diffuse between heater tracks for uniform heating. However, a lower thermal conductivity of the insulating layer reduces energy loss through the porous body. The porous heating element may extend to partially cover only the heating surface of the porous body. This has the advantage of increased power density.

[0033] Heater assemblies having an insulating layer and a porous heating element are particularly advantageous because this combination allows heat to concentrate along the heating element and restricts heat flow and dissipation to the porous material.

[0034] The heating element may have tracks. The tracks may define paths across the heated surface of the insulation layer. The tracks may define meandering paths across the heated surface of the insulation layer.

[0035] The heating element may comprise multiple tracks or track portions arranged at a distance between at least two of a plurality of tracks or track portions within a range of 150 to 300 micrometers. All tracks or track portions may be separated from at least one other track portion by a gap of 150 to 300 micrometers. This has the advantage of providing a particularly efficient heater assembly in which the aerosol-forming substrate is efficiently vaporized.

[0036] The heating element may be placed on at least one surface of the porous body. The heating element may cover at least one surface of the porous body. The heating element may enclose the porous body. The heating element may have a resistive track. When electricity is supplied, the resistive track may generate heat by Joule heating. The resistive track may have any suitable shape, including but not limited to meandering, spiral, or multiple parallel tracks.

[0037] The heating element may have a depth of up to 250 micrometers. The heating element may have a depth in the range of 0.5 micrometers to 250 micrometers. The heating element may have a depth in the range of 50 micrometers to 250 micrometers. The heating element may have a depth in the range of 5 micrometers to 50 micrometers. The heating element may have a depth in the range of 0.5 micrometers to 10 micrometers. The heating element may have a microstructure indicating that it was etched from foil, screen printed, or deposited by a thin-film deposition method.

[0038] When electricity is supplied, heat loss occurs through the porous material due to heat conduction. Heating elements with tracks are advantageous because heat loss is proportional to the heated area. The tracks may be located on the surface or a portion of the surface of the porous material. To increase power density when power is supplied, the heating element may have a surface area of ​​less than half, preferably less than one-third, preferably less than one-quarter, preferably less than one-tenth of the heated surface area of ​​the porous material. Increasing power density increases the throughput of the liquid being vaporized, reduces the time to boiling, and improves thermal efficiency (by increasing the ratio of the power used for vaporization in the porous material to power loss). Power density may be increased by reducing the width of the heater tracks. Power density may be increased by reducing the gap between the tracks of the heating element. In heater assemblies with an insulating layer, distances between at least two of multiple tracks or track portions in the range of 150 to 300 micrometers are particularly advantageous.

[0039] The heating element may comprise multiple tracks or track sections electrically arranged in parallel. The resistance of the heating element at room temperature may be 0.5 ohms to 1.5 ohms, preferably 0.7 ohms to 1.3 ohms, and more preferably 1 ohm. The resistance of the heating element may match the requirements of the control electronic circuit.

[0040] At least two of the electrically parallel heating tracks may have similar resistances to each other, or they may have identical resistances to each other. Preferably, all electrically parallel heating tracks have similar or identical resistances to each other. Electrically arranged heating tracks in parallel may have different resistances, which is particularly beneficial in heater assemblies where zones of the heating element are advantageous for generating different power levels. This may be, for example, to compensate for higher heat loss in the outer portion of the heating element. Thus, heating tracks on the outside or on the outer portion of the heating element may be designed to have lower resistances (and thus generate more heat) than the heating track in the center of the heating element.

[0041] The heating element may comprise multiple tracks or track sections defining a path having at least one bend, the inner end of the bend being curved.

[0042] The inner end of a curved bend has the advantage of guiding the current so that it flows in a more evenly distributed manner around at least one bend. This reduces current concentration and thereby limits the generation of hot spots.

[0043] The heating element may include multiple tracks or track sections having an electrical resistivity gradient perpendicular to the current flow at the corner, resulting in higher electrical resistivity on the inside of the corner and lower resistivity on the outside. Such gradients are beneficial for offsetting localized high current densities and reducing the generation of hot spots.

[0044] An embodiment of the present disclosure provides a cartridge. The cartridge may comprise a heater assembly. The cartridge may include a liquid storage portion for holding an aerosol-forming substrate. The heater assembly may comprise a heating element for vaporizing the liquid aerosol-forming substrate. The heater assembly may comprise a porous body for transporting the liquid aerosol-forming substrate to the heating element. The heater assembly may comprise an insulating layer having a lower thermal conductivity than the porous body. The insulating layer may be positioned between the porous body and the heating element, respectively. The insulating layer may be in contact with the porous body and the heating element, respectively. The insulating layer may be configured to reduce heat transfer from the heating element to the porous body. The porous body may include a porous ceramic body or a porous glass body.

[0045] According to embodiments of the present disclosure, a cartridge is provided which comprises a heater assembly and a liquid storage portion for holding a liquid aerosol forming substrate, the heater assembly comprising a heating element for vaporizing the liquid aerosol forming substrate, a porous body for transporting the liquid aerosol forming substrate to the heating element, and an insulating layer having a lower thermal conductivity than the porous body, the insulating layer being positioned between the porous body and the heating element and in contact with each of the porous body and the heating element, and the insulating layer being configured to reduce heat transfer from the heating element to the porous body.

[0046] The cartridge may include a liquid aerosol-forming substrate within the liquid storage portion. The liquid aerosol-forming substrate may be as described above.

[0047] The porous body may be fluid-connected to the liquid storage portion. The porous body may have a liquid-absorbing surface. The liquid-absorbing surface of the porous body may be fluid-connected to the liquid storage portion.

[0048] The liquid storage portion may be disposed on the liquid-absorbing surface of a porous material.

[0049] An aerosol generating system is provided. The aerosol generating system may comprise a cartridge and an aerosol generating device. The cartridge may comprise a heater assembly. The cartridge may include a liquid storage portion for holding an aerosol-forming substrate. The heater assembly may comprise a heating element for vaporizing the liquid aerosol-forming substrate. The heater assembly may comprise a porous body for transporting the liquid aerosol-forming substrate to the heating element. The heater assembly may comprise an insulating layer having a lower thermal conductivity than the porous body. The insulating layer may be placed between the porous body and the heating element. The insulating layer may be in contact with both the porous body and the heating element. The insulating layer may be configured to reduce heat transfer from the heating element to the porous body. The porous body may include a porous ceramic body or a porous glass body. The aerosol generating device may comprise a power supply for supplying power to the heating element. The aerosol generating device may comprise a control circuit configured to control the supply of power from the power supply to the heating element.

[0050] An aerosol generating system is provided, comprising a cartridge and an aerosol generating device, wherein the cartridge comprises a liquid storage section for holding a heater assembly and a liquid aerosol forming substrate, the heater assembly comprises a heating element for vaporizing the liquid aerosol forming substrate, a porous body for transporting the liquid aerosol forming substrate to the heating element, and an insulating layer having a lower thermal conductivity than the porous body, the insulating layer being positioned between the porous body and the heating element and in contact with the porous body and the heating element, and the insulating layer being configured to reduce heat transfer from the heating element to the porous body. The aerosol generating device may comprise a power supply for supplying power to the heating element and a control circuit configured to control the power supply from the power supply to the heating element.

[0051] The cartridge may include a liquid aerosol-forming substrate within the liquid storage portion. The liquid aerosol-forming substrate may be as described above.

[0052] The aerosol generating system may be portable. The aerosol generating system may be comparable in size to a conventional cigar or cigarette.

[0053] The cartridge may be detachably coupled to the aerosol generator.

[0054] The aerosol-forming substrate may be liquid at room temperature. The aerosol-forming substrate may comprise both a liquid component and a solid component. The liquid aerosol-forming substrate may contain nicotine. The nicotine-containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may contain plant-derived materials. The liquid aerosol-forming substrate may contain tobacco. The liquid aerosol-forming substrate may contain tobacco-containing materials that include volatile tobacco-flavored compounds released from the aerosol-forming substrate upon heating. The liquid aerosol-forming substrate may contain homogenized tobacco materials. The liquid aerosol-forming substrate may contain non-tobacco-containing materials. The liquid aerosol-forming substrate may contain homogenized plant-derived materials.

[0055] A liquid aerosol-forming substrate may comprise one or more aerosol-forming elements. An aerosol-forming element is any suitable known compound, or mixture of compounds, that facilitates the formation of a high-density, stable aerosol during use and is substantially resistant to thermal decomposition at the system's operating temperature. Examples of suitable aerosol-forming elements include glycerin and propylene glycol. Suitable aerosol-forming elements 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 acids, dicarboxylic acids, or polycarboxylic acids (e.g., dimethyl dodecanediol, dimethyl tetradecanediol). The liquid aerosol-forming substrate may also contain water, a solvent, ethanol, plant extracts, and natural or artificial flavors.

[0056] The liquid aerosol-forming substrate may contain nicotine and at least one aerosol-forming agent. The aerosol-forming agent may be glycerin or propylene glycol. The aerosol-forming agent may contain both glycerin and propylene glycol. The liquid aerosol-forming substrate may have a nicotine concentration of about 0.5% to about 10%, for example, about 2%.

[0057] The airflow path may pass through the liquid storage portion. For example, the liquid storage portion may have an annular cross-section defining an internal passage or aerosol channel, and the airflow path may extend through the internal passage or aerosol channel of the liquid storage portion.

[0058] The cartridge may include a cartridge housing. The cartridge housing may be formed from a durable material. The cartridge housing may be formed from a liquid-impermeable material. The cartridge housing may be formed from a moldable plastic material such as polypropylene (PP) or polyethylene terephthalate (PET), or from a copolymer such as Tritan® made from three monomers, namely dimethyl terephthalate (DMT), cyclohexanedimethanol (CHDM), and 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO). The cartridge housing may define a liquid storage portion or part of a storage portion. The cartridge housing may define a liquid storage portion. The cartridge housing and the liquid storage portion may be formed integrally. Alternatively, the liquid storage portion may be formed separately from the outer housing or disposed within the outer housing.

[0059] The aerosol generator may include a power supply for supplying power to the heater assembly. The aerosol generator may also include a control circuit for controlling the power supply from the power supply to the heater assembly. The cartridge may be detachably coupled to the aerosol generator.

[0060] The aerosol generator may include a housing. The housing may be elongated. The housing may be made of any suitable material, or a combination of such materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of these materials, or thermoplastic resins suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably lightweight and not brittle.

[0061] The aerosol generator housing may define a cavity for receiving a portion of the cartridge. The aerosol generator may have a connecting terminal configured to connect the aerosol generator to the cartridge. The connecting terminal may include a cavity for receiving the cartridge.

[0062] The power source may be any suitable power source. Preferably, the power source is a DC power source. The power source may be a battery. The battery may be a lithium-based battery, for example, a lithium cobalt battery, a lithium iron phosphate battery, a lithium titanate battery, or a lithium polymer battery. The battery may be a nickel-metal hydride battery or a nickel-cadmium battery. The power source may be another form of charge storage device, such as a capacitor. The power source may be rechargeable and may be configured to undergo multiple charge-discharge cycles. The power source may have a capacity that allows for the storage of sufficient energy for one or more user experiences of the aerosol generating system. For example, the power source may have a capacity that allows for continuous aerosol generation for about six minutes, or a multiple of six minutes, corresponding to the typical time it takes to smoke one conventional cigarette. In another embodiment, the power source may have a capacity that allows for a predetermined number of smoking sessions or for intermittent startup of the aerosol generating system.

[0063] The control circuit may include any suitable controller or electrical component. The controller may include memory. Information for performing the operation of the device or system may be stored in memory. The control circuit may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, an application-specific integrated circuit (ASIC), or other electronic circuit capable of providing control. The control circuit may be configured to supply power to the heating element continuously after the device is started, or to supply power intermittently, such as with each smoke extraction. Power may be supplied to the heating element in the form of current pulses, for example by pulse width modulation (PWM).

[0064] Features described in relation to one of the above embodiments may be equally applicable to other embodiments of the present disclosure.

[0065] The heating element may have multiple tracks or track sections. The multiple tracks or track sections may be electrically arranged in parallel. By being electrically arranged in parallel, the current flow is divided into separate parallel channels, which are then recombined.

[0066] The heating element may include a first connection pad and a second connection pad. The first or second connection pad (or the first and second connection pads) may be configured to allow connection to an external circuit. Openings or multiple openings within the heating element may isolate each track or track portion. The heating element may include at least one branching portion where the current is divided from the first connection pad to the track portions. The track portions define electrically parallel paths. The heating element may also include a merging portion. In the merging portion, the current is combined from the track portions defining electrically parallel paths to the second connection pad.

[0067] Various different arrangements of electrically arranged tracks or track sections are possible. The heating element may have two, three, four or more track sections that define electrically parallel paths.

[0068] By electrically arranging tracks or track sections in parallel, if one track section is faulty, the current can be redistributed and still flow through the heating element, i.e., the electrical connection between the first and second connecting pads is not broken. In contrast, in a simple meandering heater that defines a single electrical path between the first and second connecting pads, if a section of the meandering heating element is broken or faulty, this causes an increase in local resistance, leading to increased power dissipation and consequently increasing resistance until it breaks.

[0069] The inventors also identified that electrically parallel tracks or track sections have a surprising additional advantage. In such arrangements, if one track section fails, the heating element continues to operate and can operate in a favorable manner, as the failure of one track or track section results in a higher energy density for the remaining tracks or track sections during the initial transient period. In such cases, the same power is still provided, but it is provided over a smaller area, thus increasing the throughput of the aerosol-forming substrate. Such failures, which cause an increase in current on the undamaged tracks or track sections, can ultimately affect the user experience. This can be mitigated by a mechanism to warn the user about the potential for a future decrease in the optimal performance of the heater assembly. Electrically parallel tracks have the advantage of increasing the number of fume extractions before the heater completely fails, potentially increasing the heater's lifespan to the end of the device's life.

[0070] According to one embodiment of the present disclosure, a ceramic heating member for an aerosol generation system is provided. The ceramic heating member may include a heating portion for vaporizing a liquid aerosol-forming substrate. The ceramic heating member may include a porous portion for transporting the liquid aerosol-forming substrate to the heating portion. The heating portion and the porous portion may be integrally formed. An insulating layer may be placed between the heating portion and the porous portion.

[0071] According to one embodiment of the present disclosure, a ceramic heating member for an aerosol generation system is provided. The ceramic heating member comprises a heating portion for vaporizing a liquid aerosol-forming substrate. The ceramic heating member comprises a porous portion for transporting the liquid aerosol-forming substrate to the heating portion. The heating portion and the porous portion are integrally formed. An insulating layer is disposed between the heating portion and the porous portion.

[0072] The ceramic heating element of this embodiment provides an improved component for an aerosol generation system. By providing a ceramic heating element in which a heating portion for vaporizing a liquid aerosol-forming substrate and a porous portion for transporting the liquid aerosol-forming substrate are integrally formed, a more robust and reliable connection can be established between the heating portion and the porous portion. This can advantageously help to improve heat transfer between the heating portion and the porous portion.

[0073] Integrating the heating portion with the porous portion also has the advantage of providing a heating element that is easier to manufacture and therefore can result in a more energy-efficient heating element that can generate a more consistent aerosol. This, in turn, can provide users of the aerosol generating system with an improved and more comfortable experience. Such arrangements can also help reduce the likelihood of users experiencing dry heating or dry fumes.

[0074] The advantage of integrally forming the heating portion with the porous portion is that it helps mitigate manufacturing tolerance issues that arise in core and coil heaters, as well as in other arrangements where the heating element is removed from the liquid transfer element. The dimensions and placement of the electric heating portion relative to the porous portion are also fixed, which helps in more consistent aerosol generation. This is because the electric heating portion is fixed to the porous portion, which helps in supplying the liquid aerosol-forming substrate to the heating element. This also helps prevent undesirable heat loss, which contributes to improved energy efficiency.

[0075] By integrally forming the heating portion with the porous portion, the resulting aerosol generation system can benefit from reduced material requirements. This is because the need for intermediate components to fix the heating portion to the porous portion can be reduced or completely eliminated. Material savings can lead to cost reductions for the entire aerosol generation system. A further advantage of reduced material requirements in the overall aerosol generation system is that it provides a more sustainable and environmentally friendly solution.

[0076] These ceramic heating elements may also have the advantage of significantly reducing the risk of the heating and porous parts being removed.

[0077] The heating element, insulation layer, and porous body may be molded as a single monolithic component.

[0078] This can help simplify the manufacturing of heater assemblies by reducing manufacturing time and providing a more cost-effective solution. This can also be advantageous as it can create a tighter mechanical connection between the heating element, insulation layer, and porous body.

[0079] The heating element may be a doped portion of a porous material.

[0080] The porous material may be doped such that the portion of the porous material acting as a heat-generating element is conductive. Doping the porous material to provide a heat-generating element may be advantageous in that it avoids changes in the porosity of the porous material. This may be preferable to other known techniques for forming heat-generating elements, including depositing the heat-generating element by thin-film or thick-film techniques that can reduce the properties of the porous material, particularly the porosity. The heat-generating element doped portion may be 5 to 100 micrometers thick. The thickness of the heat-generating element doped portion may be increased if the cross-sectional area of ​​the heat-generating element is small or if the required heating resistance is high. The heat-generating element dopant used to dope the porous material may be an n-type dopant or a p-type dopant. The heat-generating element dopant may be, but is not limited to, nitrogen, phosphorus, aluminum, or boron. The interface between the insulating layer and the porous material may include a portion of the partially doped porous material.

[0081] According to one embodiment of the present disclosure, a heater assembly for an aerosol generating system is provided. The heater assembly may comprise a heating element for vaporizing a liquid aerosol-forming substrate. The heater assembly may also include a porous ceramic body for transporting the liquid aerosol-forming substrate to the heating element. The porous ceramic body may have a liquid-absorbing surface and a heating surface. The heating element may be located on the heating surface of the porous ceramic body and bonded to the heating surface of the porous ceramic body. An insulating layer may be placed between the heating element and the porous ceramic body.

[0082] According to one embodiment of the present disclosure, a heater assembly for an aerosol generating system is provided. The heater assembly comprises a heating element for vaporizing a liquid aerosol-forming substrate. The heater assembly includes a porous ceramic body for transporting the liquid aerosol-forming substrate to the heating element. The porous ceramic body has a liquid-absorbing surface and a heating surface. The heating element is located on the heating surface of the porous ceramic body and is bonded to the heating surface of the porous ceramic body. An insulating layer is placed between the heating element and the porous ceramic body.

[0083] The bonding of a heating element to the heating surface of a porous ceramic body advantageously provides a heater assembly that is easier to manufacture and assemble, and therefore can result in a more energy-efficient heater assembly that can generate a more consistent aerosol. This, in turn, can provide users of the aerosol generating system with an improved and more comfortable experience. Such arrangements can also help reduce the likelihood of users experiencing dry heating or dry fumes.

[0084] The advantage of providing and bonding the heating element to the heating surface of a porous ceramic body is that it helps mitigate the manufacturing tolerance issues that arise in other arrangements where the core and coil heater and heating element are separated from the liquid transport element. The dimensions and placement of the electric heating element relative to the porous body are also fixed, which helps in more consistent aerosol production. This is because the electric heating element is fixed to the porous ceramic body, which helps in supplying the heating element with a liquid aerosol-forming substrate. This also helps prevent undesirable heat loss, which contributes to improved energy efficiency.

[0085] By providing a heating element on the heated surface of a porous ceramic body and bonding an insulating layer between them, the resulting aerosol generation system can benefit from reduced material requirements. This is because the need for intermediate fixing components to secure the heating element to the porous body can be reduced or completely eliminated. Material savings can lead to cost reductions for the entire aerosol generation system. A further advantage of reduced material requirements in the overall aerosol generation system is that it provides a more sustainable and environmentally friendly solution.

[0086] An aerosol generating system is provided according to one embodiment of the present disclosure. The aerosol generating system may include the heater assembly described above. The heating element may be fluid permeable so that vapor is released from the heater assembly in the mean vapor discharge direction during use. The aerosol generating system may further include an air intake and an aerosol outlet. The air intake may be in fluid communication with the aerosol outlet to define an airflow path through the aerosol generating system. The heater assembly may be arranged in fluid communication with the airflow path so that air flows through the heater assembly in the mean airflow direction. The heater assembly and the airflow path may be arranged such that the angle between the mean vapor discharge direction and the mean airflow direction is less than 135 degrees.

[0087] Advantageously, by arranging the heater assembly and airflow path so that the angle between the mean vapor discharge direction and the mean airflow direction is less than 135 degrees, the mean airflow direction does not directly oppose the mean vapor discharge direction. Therefore, the momentum of the vapor and airflow is not reduced as much as when the mean airflow direction directly opposes the mean vapor discharge direction. This reduces the tendency for recirculation and turbulence to occur within the airflow path, and the vapor is less likely to collide with the internal surfaces of the aerosol generation system. Consequently, the likelihood of aerosol condensation occurring within the aerosol generation system is reduced.

[0088] The average vapor emission direction may be substantially perpendicular to the heated surface of the insulating layer. The average vapor emission direction may be substantially perpendicular to the heated surface of the porous body. As used herein, the term “substantially perpendicular” means 90 degrees plus or minus 10 degrees, preferably plus or minus 5 degrees.

[0089] The advantage of an average vapor discharge direction substantially perpendicular to the heated surface of the insulating layer is that, because the vapor is discharged substantially perpendicular to the heated surface of the insulating layer, it becomes easier to orient it relative to the average airflow direction. Therefore, by appropriately angling the heater assembly with respect to the airflow in the airflow path, or vice versa, a desirable angle between the average vapor discharge direction and the average airflow direction can be achieved.

[0090] The heater assembly and airflow path may be arranged such that the angle between the average vapor discharge direction and the average airflow direction is less than 110 degrees, preferably less than 100 degrees.

[0091] The heater assembly and airflow path may be arranged such that the angle between the mean vapor discharge direction and the mean airflow direction is approximately 90 degrees. This arrangement causes the vapor to be discharged at an angle substantially perpendicular to the mean airflow direction. The mean vapor discharge direction has no velocity or directional component opposed to the airflow direction, and therefore the loss of momentum in the airflow is reduced. This reduces the tendency for recirculation and turbulence to occur within the airflow path, and the vapor is less likely to collide with the internal surfaces of the aerosol generating system. Furthermore, the mixing of vapor into the airflow is improved. Therefore, the likelihood of aerosol condensation occurring within the aerosol generating system is reduced.

[0092] The heater assembly and airflow path may be arranged such that the angle between the mean vapor discharge direction and the mean airflow direction is less than 90 degrees. In this arrangement, the mean vapor discharge direction has no velocity or directional component opposed to the airflow direction, and in fact has velocity and directional components in the same direction as the mean airflow direction. Thus, momentum loss of the airflow is further reduced. This reduces the tendency for recirculation and turbulence to occur within the airflow path, and the vapor is less likely to collide with the internal surfaces of the aerosol generating system. Furthermore, vapor mixing into the airflow is improved. Thus, the likelihood of aerosol condensation occurring within the aerosol generating system is reduced.

[0093] The heater assembly and airflow path may be arranged such that the angle between the mean vapor discharge direction and the mean airflow direction is approximately 45 degrees. The heater assembly and airflow path may be arranged such that the angle between the mean vapor discharge direction and the mean airflow direction is less than 45 degrees.

[0094] The heater assemblies and airflow paths may be arranged such that the mean vapor discharge direction and the mean airflow direction are substantially the same. In this arrangement, since the mean vapor discharge direction and the mean airflow direction are the same, there is virtually no loss of momentum in the airflow. This reduces the tendency for recirculation and turbulence to occur within the airflow path, and the vapor is less likely to collide with the internal surfaces of the aerosol generating system. Furthermore, the mixing of vapor into the airflow is improved. Therefore, the likelihood of aerosol condensation occurring within the aerosol generating system is reduced.

[0095] The cross-sectional area of ​​the airflow path in the heater assembly region may be configured such that the airflow velocity during use is 0.1 to 2 meters / second, preferably 0.5 to 1.5 meters / second, and more preferably about 1 meter / second. It has been found that airflow velocities in this range effectively entrain steam released from different designs of the heating element without excessively cooling the heating element.

[0096] The heating element may comprise a porous layer of conductive material. Advantageously, a heating element comprising a porous layer of conductive material allows resistance heating of the heating element and also allows current to flow through the heating element, enabling vapor to move through the pores within its porous structure. Therefore, vapor release occurs through the porous heating element. This avoids the accumulation of vapor pressure beneath the heating element and rapid vapor release at the sides of the heating element. The inventors found that this arrangement generates consistent vapor across the heating element, resulting in a low vapor release velocity of approximately 0.1 meters / second. Such a low vapor release velocity means that the vapor is easily carried by an airflow that reduces vapor collisions on the inner walls of the aerosol generating system.

[0097] The porous body may have a liquid-absorbing surface and a heating surface. The insulating layer may be placed on the heating surface. The liquid-absorbing surface of the porous body may have a region different from the heating surface region of the porous body. The porous body may include a porous ceramic body or a porous glass body. The porous body may be substantially incompressible. The porous body may be incompressible.

[0098] A heater assembly having a heating surface with the same area as the liquid absorption surface may be inefficient due to the heat generated by the heater used to vaporize the aerosol-forming substrate. An inefficient heater assembly results in reduced aerosol throughput.

[0099] Advantageously, providing a porous material in which the heating surface and the liquid absorption surface have different regions can improve the throughput of aerosols that may be generated by the heater assembly compared to a heater assembly in which the heating surface has the same region as the liquid absorption surface.

[0100] Increased heating efficiency may reduce power consumption during use of the heater assembly.

[0101] The heating surface area of ​​the porous material may be smaller than the liquid-absorbing surface area of ​​the porous material. The heating surface area of ​​the insulating layer may be smaller than the liquid-absorbing surface area of ​​the porous material. The liquid-absorbing surface area of ​​the porous material may be larger than the heating surface area of ​​the porous material. The liquid-absorbing surface area of ​​the porous material may be larger than the heating surface area of ​​the insulating layer.

[0102] Advantageously, if the porous material has a shape such that the heated surface has a smaller area than the liquid-absorbing surface, the heat that flows from the heating element to the liquid storage portion via the liquid-absorbing surface can be reduced. The relatively small heated surface provides a small heat transfer region through which heat can be transferred by conduction from the heating element to the porous material and toward the liquid-absorbing surface.

[0103] Since much of the thermal energy provided by the heating element can be used to vaporize the aerosol-forming substrate, reducing heat loss from the heating element to the porous bulk can consequently increase heating efficiency. As a result, porous materials with a shape in which the heated surface has a smaller area than the liquid-absorbing surface can increase the aerosol throughput generated by the heater assembly.

[0104] Advantageously, a porous body having a shape such that the heating surface has a smaller area than the liquid absorption surface can reduce the area of ​​the heating surface that is not close enough to the heating element for the aerosol-forming substrate transported to the heating surface to vaporize. In other words, the size and shape of the heating surface may more closely match the size and shape of the heating element. As a result, more liquid aerosol-forming substrate may be transported from the liquid absorption surface to the region of the heating surface closer to the heating element, thereby allowing more liquid aerosol-forming substrate on the heating surface to vaporize. An increase in the vaporized liquid aerosol-forming substrate can increase the aerosol throughput generated by the heater assembly. Furthermore, this arrangement may allow for maximization of the power density on the heating surface, which also improves heating efficiency.

[0105] Advantageously, a liquid absorption surface having a larger surface area than the heating surface may allow the liquid absorption surface to receive a larger volume of liquid aerosol substrate from the liquid storage portion. As a result of the relatively small area of ​​the heating surface, the flow rate of liquid aerosol-forming substrate to the heating element may be higher than the flow rate in a typical heater assembly as the liquid aerosol-forming substrate is transported through the porous material toward the heating surface. An increased flow rate of liquid aerosol-forming substrate in the heating element may increase the aerosol throughput generated by the heater assembly.

[0106] The area of ​​the heated surface of the porous material may be larger than the area of ​​the liquid-absorbing surface of the porous material. The area of ​​the liquid-absorbing surface of the porous material may be smaller than the area of ​​the heated surface of the porous material.

[0107] Advantageously, if the porous material has a shape such that the liquid absorption surface has a smaller area than the heating surface, the smaller liquid absorption surface area can lead to a reduction in heat flow from the heating element to the liquid absorption surface through the aerosol-forming substrate via heat conduction. Since much of the thermal energy provided by the heating element can be used to vaporize the liquid aerosol-forming substrate, reducing the heat flow from the heating surface to the liquid absorption surface can consequently increase thermal efficiency. As a result, porous materials with a shape such that the liquid absorption surface has a smaller area than the heating surface can improve heating efficiency, which can increase the throughput of aerosols generated by the heater assembly.

[0108] Advantageously, a porous body having a shape such that the liquid absorption surface has a smaller area than the heating surface can reduce the area of ​​the heating surface that is not close enough to the heating element for the aerosol-forming substrate transported to the heating surface to vaporize. In other words, the size and shape of the heating surface may more closely match the size and shape of the heating element. As a result, more liquid aerosol-forming substrate may be transported from the liquid absorption surface to the heating surface region closer to the heating element, thereby allowing more liquid aerosol-forming substrate on the heating surface to vaporize. An increase in the vaporized liquid aerosol-forming substrate can increase the aerosol throughput generated by the heater assembly.

[0109] The heated surface of the porous body may be convex in one or both of the first and second transverse directions, with the first transverse direction being perpendicular to the second transverse direction. The insulating layer may be placed on the heated surface of the porous body. The heated surface of the insulating layer may be convex in one or both of the first and second transverse directions, with the first transverse direction being perpendicular to the second transverse direction.

[0110] By including such porous materials or insulating layers, it may be possible to increase the surface area of ​​the heated surface without increasing the volume of the porous material. This may improve the efficiency of the heater assembly when vaporizing the liquid aerosol-forming substrate, as it may allow the surface area of ​​the heating assembly available for vaporizing the liquid aerosol-forming substrate to increase without increasing the volume of the porous material where heat loss can occur through conduction.

[0111] Providing a heating surface that is convex in one or both of the first transverse direction and the second transverse direction is a heating surface This may allow for an increase in the surface area of ​​the heated surface without increasing its width. This can help improve the efficiency of the heater assembly in vaporizing the liquid aerosol-forming substrate while avoiding the need to redesign other components of the aerosol generation system to accommodate the porous material.

[0112] Providing a heating surface that is convex along one or both of the first and second transverse directions may help avoid or minimize recirculation of the airflow adjacent to the heater assembly. In particular, a convex heating surface may help avoid or minimize recirculation of the airflow adjacent to the central region of the heater assembly. This may reduce the level of turbulence in the airflow adjacent to the heater assembly. Reducing the level of turbulence in the airflow adjacent to the heater assembly may improve the incorporation of aerosol-forming substrate vapors into the airflow. This may improve the quality of the aerosols generated by the aerosol generating system.

[0113] Improving the inclusion of vapors in the airflow through an aerosol generation system can avoid or reduce vapor condensation, which is necessary for the formation of larger droplets of the liquid aerosol-forming substrate. This can help avoid an unpleasant and undesirable user experience.

[0114] Improving the inclusion of vapors in the airflow through an aerosol generating system can prevent or reduce condensation of vapors on the internal surface of the aerosol generating system. This can help prevent or minimize damage to the aerosol generating system and enable its optimal functioning.

[0115] The heated surface of the porous body or insulating layer may be convex in a single transverse direction.

[0116] The heated surface of the porous body or insulating layer may be convex in both the first transverse direction and the second transverse direction.

[0117] The heating surface of the porous body or insulating layer may be convex in one or both of the first and second transverse directions, based on the configuration of the heater assembly with respect to one or more airflow paths in the aerosol generating system. The heater assembly may be configured to minimize the level of turbulence in the airflow adjacent to the heater assembly. For example, it may be advantageous for the heater assembly to be positioned within the aerosol generating system such that the air drawn into the aerosol generating system follows a curved path along at least a portion of the curved surface of the heater assembly.

[0118] The heating element may be convex in one or both of the first and second transverse directions.

[0119] The curvature of the heating element or insulating layer in the first transverse direction may be substantially the same as the curvature of the porous body or the heated surface of the insulating layer in the first transverse direction. The curvature of the heating element or insulating layer in the second transverse direction may be substantially the same as the curvature of the porous body or the heated surface of the insulating layer in the second transverse direction. The curvature of the heating element or insulating layer in both the first and second transverse directions may be substantially the same as the curvature of the porous body or the heated surface of the insulating layer in both the first and second transverse directions, respectively.

[0120] The average pore size of a porous material can vary between the liquid-absorbing surface and the heated surface of the porous material.

[0121] Providing a porous material that includes variations in pore size between the liquid-absorbing surface and the heating surface of the porous material can, advantageously, help control the transport of the liquid aerosol-forming substrate from the storage portion to the heating element. Specifically, the variation in pore size between the liquid-absorbing surface and the heating surface of the porous material can enable the porous material to provide a consistent supply of the aerosol-forming substrate to the heating surface. This can, advantageously, avoid undesirable "dry heating." Furthermore, the porous material of the present invention can also, advantageously, prevent leakage of the liquid aerosol-forming substrate from the heating surface of the porous material.

[0122] The average pore size of a porous material can vary in any way between the liquid-absorbing surface and the heated surface of the porous material. The average pore size can change so that the pores are relatively large at the liquid-absorbing surface and relatively small at the heated surface.

[0123] Providing a porous body having a larger average pore diameter at the liquid absorption end and a smaller average pore diameter at the heating end of the porous body can particularly facilitate the efficient movement of a liquid aerosol-forming substrate from the liquid absorption end to the heating end of the porous body without causing leakage. In particular, the inventors of the present invention have identified that the liquid aerosol-forming substrate moves from the liquid absorption end to the heating end of the porous body by capillary action. How quickly the liquid aerosol-forming substrate moves through the porous body depends on many factors, including, but not limited to, the geometric shape of the pores, the surface tension between the liquid aerosol-forming substrate and the porous body, the viscosity of the liquid aerosol-forming substrate, the surface tension of the liquid aerosol-forming substrate, and the overall geometric shape of the porous body. The inventors of the present invention have identified the need to balance these factors while preventing leakage of the liquid aerosol-forming substrate and providing efficient movement of the liquid aerosol-forming substrate to the heating surface of the porous body.

[0124] Firstly, to provide efficient capillary flow of liquid through the porous material, the capillary pressure must not exceed the viscous drag pressure. Secondly, to prevent leakage, the inertial force must not exceed the capillary pressure. These two requirements are met by providing a porous material having larger pores at the liquid absorption end and smaller pores at the heating end of the porous material.

[0125] In particular, the inventors of the present invention recognized that the viscosity of the liquid aerosol-forming substrate changes with temperature. Specifically, the viscosity of the liquid aerosol-forming substrate decreases as its temperature increases. As a result, the viscosity of the liquid aerosol-forming substrate decreases as it moves through the porous material from the liquid absorption surface to the heated surface of the porous material. Since the liquid aerosol-forming substrate is transported through the porous material by capillary force, the capillary force must overcome the viscous drag of the liquid. Viscous drag decreases as viscosity decreases. As a result, the capillary force required to move the liquid aerosol-forming substrate decreases toward the heated surface of the porous material while still maintaining the same flow rate. Consequently, the average pore size of the porous material can decrease toward the heated surface of the porous material without reducing the flow of the liquid aerosol-forming substrate through the porous material.

[0126] Features described in relation to one of the above embodiments may be equally applicable to other embodiments of the present disclosure. [Examples]

[0127] The present invention is defined in the claims. However, a non-exclusive list of non-limiting embodiments is provided below. One or more features of these embodiments may be combined with one or more features of other embodiments, forms, or aspects described herein.

[0128] Example 1. A heater assembly for an aerosol generator, wherein the heater assembly is A heat-generating element for vaporizing the liquid aerosol-forming substrate, A porous body for transporting a liquid aerosol-forming substrate to a heating element, A heater assembly comprising: an insulating layer having a lower thermal conductivity than a porous body, wherein the insulating layer is positioned between the porous body and the heating element and is in contact with them, and is configured to reduce heat transfer from the heating element to the porous body, and the porous body includes a porous ceramic body or a porous glass body. Example 2. The heater assembly according to Example 1, wherein the insulation layer contains an insulating material, and the insulating material has a lower thermal conductivity than the porous material. Example 3. A heater assembly according to Example 1 or 2, wherein the insulation layer comprises a material having a thermal conductivity of less than 40 watts / meter·Kelvin. Example 4. A heater assembly according to any one of Examples 1 to 3, wherein the insulation layer comprises a material having a thermal conductivity of less than 10 watts / meter·Kelvin. Example 5. A heater assembly according to any one of Examples 1 to 4, wherein the insulation layer contains an insulating material, and the insulating material has a higher porosity than a porous material. Example 6. A heater assembly according to any of Examples 1 to 5, wherein the insulating layer extends throughout the space between the porous body and the heating element. Example 7. A heater assembly according to any one of Examples 1 to 6, wherein the insulating layer contains one or more of alumina, zirconia, zirconia containing magnesium oxide, glass ceramic, quartz, and porous polymer. Example 8. A heater assembly according to any one of Examples 1 to 7, wherein the heat insulating layer has a thickness of 0.1 mm to 2 mm, preferably 0.5 mm to 1.5 mm. Example 9. A heater assembly according to any of Examples 1 to 8, wherein the heating element is a porous heating element. Example 10. A heater assembly according to any one of Examples 1 to 9, wherein the insulating layer has a heating surface, and the heating element extends to cover the heating surface area of ​​the insulating layer. Example 11. A heater assembly according to any one of Examples 1 to 10, comprising multiple tracks or track sections, wherein the heating element is arranged such that the distance between at least two of the multiple tracks or track sections is in the range of 150 to 300 micrometers. Example 12. A heater assembly according to any of Examples 1 to 11, wherein the porous body contains an electrical insulating material. Example 13. A heater assembly according to any of Examples 1 to 12, wherein the heating element and the porous body are integrally formed. Example 14. A heater assembly according to any one of Examples 1 to 13, wherein the heat insulating layer has a heating surface, and the heating element is located on the heating surface of the heat insulating layer and bonded to it. Example 15. The porous material has a liquid-absorbing surface and a heating surface, The heating element and the insulating layer are located on the heated surface of the porous body. A heater assembly according to any one of Examples 1 to 14, wherein the liquid-absorbing surface of the porous material has a region different from the heating surface region of the porous material. Example 16. The heater assembly described in Example 15, wherein the heating surface area of ​​the porous material is smaller than the liquid-absorbing surface area of ​​the porous material. Example 17. The heater assembly according to Example 14 or 15, wherein the area of ​​the liquid-absorbing surface of the porous material is smaller than the area of ​​the heating surface of the porous material. Example 18. A porous ceramic body has a liquid absorption surface and a heating surface, The heating element and the insulating layer are located on the heated surface of the porous ceramic body. A heater assembly according to any of Examples 1 to 17, wherein the heating surface of the porous body is convex in one or both of the first transverse direction and the second transverse direction, and the first transverse direction is perpendicular to the second transverse direction. Example 19. The heater assembly according to Example 18, wherein the heating surface of the porous material has a radius of curvature of at least about 1.5 millimeters. Example 20. The porous material has a liquid-absorbing surface and a heating surface, The heating element is placed on the heated surface of the porous body. A heater assembly according to any of Examples 1 to 19, wherein the average pore size of the porous material changes between the liquid absorption surface and the heating surface. Example 21. A heater assembly according to Example 20, wherein a heating element, an insulating layer, and a porous body are integrally formed. Example 22. The porous body has a heating end and a liquid absorption end, with the heating surface located at the heating end and the liquid absorption surface located at the liquid absorption end. A heater assembly according to Example 20 or Example 21, wherein the porous body has a first average pore diameter at the liquid absorption end and a second average pore diameter at the heating end, and the first average pore diameter is larger than the second average pore diameter. Example 23. A heater assembly according to any of Examples 1 to 22, wherein the heating element comprises multiple tracks or track sections electrically arranged in parallel. Example 24. A heater assembly according to any one of Examples 1 to 23, wherein the heating element comprises a plurality of tracks or track portions defining a path having at least one bend, the inner end of the bend being curved. Example 25. An aerosol generating system comprising a heater assembly as described in any of Examples 1 to 24, wherein the heating element is fluid permeable so that vapor is released from the heater assembly in the mean vapor discharge direction during use, The aerosol generation system further comprises an air intake and an aerosol outlet, the air intake and the aerosol outlet being in fluid communication to define an airflow path through the aerosol generation system. An aerosol generating system in which a heater assembly is arranged in fluid communication with an airflow path so that air flows through the heater assembly in the mean airflow direction, and the heater assembly and airflow path are arranged such that the angle between the mean vapor emission direction and the mean airflow direction is less than 135 degrees. [Brief explanation of the drawing]

[0129] Here, we will further describe the embodiment with reference to the attached drawings.

[0130] [Figure 1] Figure 1 is a schematic cross-sectional view of a heater assembly according to an embodiment of the present disclosure, and the heating element is a truck heater. [Figure 2] Figure 2 is a schematic cross-sectional view of a heater assembly according to an embodiment of the present disclosure, in which the heating element is a porous layer. [Figure 3] Figures 3(a) to 3(c) are graphs showing the effect of increased thermal conductivity on various factors. [Figure 4] Figures 4(a) to 4(c) are graphs showing the effects of increasing power density on (a) time to boiling, (b) throughput, and (c) thermal efficiency. [Figure 5] Figures 5(a) and 5(b) are schematic diagrams showing the current flowing through a porous heating element, with (a) showing the case without defects and (b) showing the case with defects. [Figure 6] Figures 6(a) to 6(c) are schematic diagrams depicting the heat source track. [Figure 7] Figures 7(a) and 7(b) are schematic diagrams showing the current flow around the corners of the heating element track. [Figure 8] Figure 8 is a schematic plan view of a heater assembly according to an embodiment of the present disclosure. [Figure 9] Figure 9 is a schematic cross-sectional view of the heater assembly shown in Figure 8. [Figure 10] Figure 10 is a schematic diagram of the inside of an aerosol generation system according to an embodiment of the present disclosure. [Figure 11] Figure 11 is a schematic cross-sectional view of a portion of an aerosol generating system according to another embodiment of the present disclosure, showing the arrangement of a heater assembly with respect to the airflow path within the aerosol generating system. [Figure 12] Figure 12 is a schematic cross-sectional view of a portion of another aerosol generating system according to another embodiment of the present disclosure, showing a different arrangement of the heater assembly relative to the airflow path within the aerosol generating system. [Figure 13] Figure 13 is a schematic diagram of a heater assembly according to one embodiment of the present disclosure. [Figure 14] Figure 14 is a side view of the schematic diagram in Figure 13. [Figure 15] Figure 15 is a schematic diagram of a heater assembly according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0131] The above and other features and advantages of the exemplary embodiments will become further apparent by describing the exemplary embodiments in detail with reference to the accompanying drawings. However, the details of certain structural and functional aspects disclosed herein are merely typical for the purpose of illustrating the exemplary embodiments. However, the exemplary embodiments may be embodied in numerous alternative forms and should not be construed as being limited to the embodiments described herein.

[0132] As a result, while exemplary embodiments are subject to various modifications and alternative forms, these embodiments are shown in the drawings as examples and will be described in detail herein. Naturally, however, there is no intention to limit the embodiments to any particular form disclosed; on the contrary, the exemplary embodiments encompass all modifications, equivalents, and alternatives that fall within the scope of the exemplary embodiments. Similar figures refer to similar elements throughout the description of the figures.

[0133] Spatial relationship terms (e.g., “downward”) may be used herein to facilitate explanation, as shown in the figures, to describe the relationship between one element or feature and another. Naturally, spatial relationship terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, the element described as “downward” of the other element or feature will then be oriented “above” the other element or feature. Thus, the term “downward” may encompass both upward and downward orientations. The device may be oriented in other ways (by rotating 90 degrees or in other orientations), and the spatial relationship terms used herein will be interpreted accordingly.

[0134] When it is said that one element or layer is "placed on top of" another element or layer, it should be understood that the element or layer may be directly on top of the other element or layer, directly connected to it, directly bonded to it, directly cover it, or there may be an intervening element or layer. In contrast, when it is said that one element is "placed on top of" another element or layer, there is no intervening element or layer.

[0135] The terms used herein are for illustrative purposes only and are not intended to limit the exemplary embodiments. The singular forms “a,” “an,” and “the” used herein are intended to include the plural, unless the context clearly indicates otherwise. The terms “includes,” “including,” “comprises,” and “comprising,” when used herein, identify the presence of the described feature, integer, process, operation, or element, but do not exclude the presence or addition of one or more other features, integers, processes, operations, elements, or groups thereof.

[0136] The exemplary embodiments are described herein with reference to schematic cross-sectional views of ideal embodiments (and intermediate structures) of the exemplary embodiments. Thus, variations from the exemplary shapes, for example, resulting from manufacturing techniques or tolerances, are expected. Accordingly, the exemplary embodiments should not be construed as limiting the shapes of the regions illustrated herein, and include deviations in shape resulting, for example, from manufacturing. Accordingly, the regions illustrated in the figures are essentially schematic, and their shapes are not intended to illustrate the actual shapes of the regions of the apparatus, nor are they intended to limit the scope of the exemplary embodiments. The same reference numerals indicate the same elements throughout the drawings. The accompanying drawings should not be considered to be drawn to actual size unless otherwise specified. It will be understood that the drawings of this application are schematic and that some features have been omitted for clarity.

[0137] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as those generally understood by those skilled in the art to the extent of the exemplary embodiments. Furthermore, terms (including those defined in commonly used dictionaries) should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, unless expressly defined herein, and not as ideal or overly formal.

[0138] The accompanying drawings are intended to illustrate exemplary embodiments and should not be construed as limiting the intended claims.

[0139] Referring to Figure 1, a schematic diagram of a heater assembly 100 for an aerosol generating system according to one embodiment of the present disclosure is shown. The heater assembly 100 comprises a heating element 110, an insulating layer 120, a porous body 130, and an electrical control circuit (not shown for clarity).

[0140] The porous body 130 is configured to supply the liquid aerosol-forming substrate to the heating element 110. Specifically, the porous body 130 is configured to transport the liquid aerosol-forming substrate from the liquid storage section (not shown in Figure 1 for clarity) to the heating element 110. The porous body 130 is configured to store a portion of the liquid aerosol-forming substrate until it is aerosolized by the heating element 110.

[0141] The porous body 130 is a rectangular block. The porous body 130 has a first end face and an opposing second end face. The first end face is a liquid absorption surface 134, and the second end face is a heating surface 133. In this embodiment, both the liquid absorption surface 134 and the heating surface 133 are substantially flat surfaces. The porous body 130 also has a plurality of sides extending between the liquid absorption surface 134 and the heating surface 133. The porous body 130 has a first side face 131 opposite to a second side face 132, and a third side face (not shown) opposite to a fourth side face (not shown). The porous body 130 has a thickness defined between the liquid absorption surface 134 and the heating surface 133.

[0142] The porous body 130 contains a plurality of open pores. The plurality of open pores are interconnected to provide a fluid path for the aerosol-generating liquid to pass through the porous body 130. The heater assembly 100 may be configured so that the liquid can pass through the fluid path in the porous body 130 to the heating element 110, as indicated by arrow 170. The porous body 130 is configured so that the fluid 170 passes from the liquid absorption side 134 to the heating surface 133. The porous body 130 includes a material that does not chemically interact with the liquid aerosol-forming substrate. The porous body 130 includes a ceramic. The porous body 130 includes, but is not limited to, one or more porous ceramics such as Al2O3, ZrO2, Si3N4, SiC, Ti3AlC2, BN, AlN, SiO2, MgO, mica, diatomaceous earth, silicates, borides, and glass. It will be understood that the porous body 130 may have a different shape or may contain different materials.

[0143] The heating element 110 is configured to heat the liquid aerosol-forming substrate in order to form an aerosol. The heating element 110 is configured to convert electrical energy into thermal energy through the material resistance of the heating element 110 to electric current.

[0144] The heating element 110 has tracks that define a path across the heated surface 123 of the insulating layer 120. The heating element 110 defines a meandering or electrically parallel track shape across the heated surface 123 of the insulating layer 120. Figure 1 shows three cross-sections passing through a portion of the track of the heating element 110. The multiple track portions are arranged at a distance between at least two of the multiple track portions 118, 119, in the range of 150 to 300 micrometers. The track portions are evenly spaced. It will be understood that the distances between at least two of the multiple track portions 118, 119 do not have to be equal.

[0145] The heating element 110 has an elongated shape. The heating element 110 includes, but is not limited to, metals such as stainless steel, Ni-Cr alloy, NiCrAlY alloy, FeCrAl alloy (e.g., Kanthal), FeCrAlY alloy, Fe3Al alloy, Ni3Al alloy, NiAl alloy, and CuNi alloy. Naturally, the heating element 110 may have a different shape or contain different materials.

[0146] The heating element 110 is arranged along the outer surface of the insulation layer 120. The heating element 110 is in direct contact with the insulation layer 120.

[0147] The insulation layer 120 is arranged to enhance the insulation between the heat-generating element 110 and the porous body 130. The insulation layer 120 extends over at least a portion of the heat-generating element 110 and is arranged to insulate the heat-generating element 110 from the porous body 130. The insulation layer 120 is configured to reduce heat dissipation through the porous body 130 in order to improve energy efficiency by reducing energy loss.

[0148] The insulation layer 120 is planar. The insulation layer 120 has a size and shape configured to extend across the electric heating element 110. The insulation layer 120 is configured to extend across the entire surface of the heating element 110. The insulation layer 120 is configured to substantially cover the porous body 130 beneath the insulation layer 120.

[0149] The thermal insulation layer 120 has a first end face and an opposing second end face. The first end face is a liquid absorption surface 124, and the second end face is a heating surface 123. In this embodiment, both the liquid absorption surface 124 and the heating surface 123 are substantially flat surfaces. The liquid absorption surface 124 of the thermal insulation layer 120 is in direct contact with the porous body 130. The heating surface 123 of the thermal insulation layer 120 is in direct contact with the heating element 110.

[0150] The thermal insulation layer 120 also has a plurality of sides extending between the liquid absorption surface 124 and the heating surface 123. The thermal insulation layer 120 has a first side 121 facing a second side 122 and a third side (not shown) facing a fourth side (not shown).

[0151] The insulation layer 120 is configured such that its first side surface 121 extends to the first side surface 131 of the porous body 130. The insulation layer is configured such that its second side surface 122 extends to the second side surface 132 of the porous body 130. The insulation layer is configured such that its third side surface extends to the third side surface of the porous body 130. The insulation layer is configured such that its fourth side surface extends to the fourth side surface of the porous body 130.

[0152] The thermal insulation layer 120 has a defined thickness between the liquid absorption surface 124 and the heating surface 123. The thickness of the thermal insulation layer 120 is less than the thickness of the porous body 130. The thermal insulation layer may have a thickness of 0.1 mm to 2 mm, preferably 0.5 mm to 1.5 mm.

[0153] The thermal insulation layer 120 contains a material having a low thermal conductivity. The thermal insulation layer 120 contains, or consists of, a material having a lower thermal conductivity than the porous body 130. The thermal insulation layer 120 may have a higher porosity than the porous body 130. The thermal insulation layer 120 may contain one or more materials such as alumina, zirconia, zirconia containing magnesium oxide, glass ceramic, quartz, and porous polymers. It will be understood that the thermal insulation layer 120 may have different shapes or contain different materials.

[0154] Referring to Figure 2, a schematic diagram of a heater assembly 100 for an aerosol generating system according to a second embodiment of the present disclosure is shown. The heater assembly 100 comprises a heating element 110, an insulating layer 120, a porous body 130, and an electrical control circuit (not shown for clarity).

[0155] The porous body 130 and the heat insulating layer 120 are as described in relation to the embodiment shown in Figure 1.

[0156] The heating element 110 in the second embodiment is a porous heating element. The heating element 110 extends to cover the heated surface area of ​​the insulating layer 120.

[0157] The heating element 110 has a first end face and an opposing second end face. The first end face is a liquid-absorbing surface 114, and the second end face is an outer surface 113. In this embodiment, both the liquid-absorbing surface 114 and the outer surface 113 are substantially flat surfaces. The liquid-absorbing surface 114 of the heating element 110 is in direct contact with the heat insulating layer 120.

[0158] The heating element 110 also has a plurality of sides extending between the liquid-absorbing surface 114 and the outer surface 113. The heating element 110 has a first side 111 facing a second side 112 and a third side (not shown) facing a fourth side (not shown).

[0159] The heating element 110 is configured such that its first side surface 111 extends to the first side surface 121 of the insulation layer 120. The heating element 110 is configured such that its second side surface 112 extends to the second side surface 112 of the insulation layer 120. The heating element 110 is configured such that its third side surface extends to the third side surface of the insulation layer 120. The heating element 110 is configured such that its fourth side surface extends to the fourth side surface of the insulation layer 120.

[0160] In the first and second embodiments, heat loss from the heating element to the porous body and to the liquid within the porous body is reduced. Compared to known devices without an insulating layer, the heater assemblies of the first and second embodiments are more efficient because they allow for increased user usage and frequency of the device before the device battery is depleted.

[0161] To further demonstrate the problems addressed by the insulation layer, the following simulation shows heat loss and dissipation in a known heater assembly without an insulation layer. Such a known heater assembly has a porous body and an electrically heated element.

[0162] As a first approximation, heat is considered to dissipate within the porous body away from the heater solely through diffusion (i.e., thermal diffusion without considering convection induced by liquid movement toward the heated surface). In this case, the heat diffuses over distance d according to equation (1).

number

[0163] In the formula, α M This indicates the thermal diffusivity of the porous material and the liquid containing it, and t P This refers to the duration of smoking.

[0164] α M 9.2e-8m 2 / s and t P If the time is 3 seconds, then d = 1.1 mm.

[0165] In a second approximation that can more accurately model heat dissipation, the liquid is considered to flow towards the heated surface, restricting the diffusion of heat from the heated region. In this case, heat conduction in the porous body is the result of a competition between heat diffusion (where heat is transferred from the heated surface to the bulk material of the porous body) and convection (where the flow of the liquid returns heat to the heated surface).

[0166] In such an approximation, the temperature profile T(z) with respect to the distance z from the heated surface asymptotically approaches a steady-state profile defined as follows.

Equation

[0167] where z = 0 at the heated surface and z < 0 when at a certain distance from the heated surface within the porous body, T R R is the temperature of the liquid in the reservoir, T H H is the temperature of the heated surface of the heating element, ε W W is the porosity of the porous body, u L L is the velocity of the liquid towards the heated region within the porous body.

[0168] When the temperature of the heating element is 250 °C, the thermal diffusivity of the porous body is 9.2e-8 m 2 2 / s, the liquid flows through the porous body of the vaporization region of 25 mm 2 2 at a rate of 0.2 ml / min with a porosity of 50 percent, and the heat diffuses α M M / (ε W u L L )= 0.5 mm backward (i.e., away from the heating element and into the porous body).

[0169] In this approximation, to reduce heat loss in the porous body, it is necessary to minimize the diffusion of heat away from the heated surface. This requires one or more of the following: · A high liquid flow rate (u L L ) within the porous body, · A high porosity (ε W W ) in the porous body, ·Low thermal diffusivity (α M ).

[0170] Thermal diffusivity α M This is the ratio of the thermal conductivity k, expressed by equation (3), to the volumetric heat capacity. α M =k / (ρc p ) (3)

[0171] In the formula, ρ is the material density, and c p This is the specific heat capacity of the material.

[0172] Thermal diffusivity can be reduced by selecting porous materials with high specific heat capacity and low thermal conductivity. Porous materials such as cotton, alumina, and zirconia are 10 -8 ~3×10 -5 m 2 It has low thermal conductivity combined with a reasonable specific heat capacity that results in a low thermal diffusivity in the range of / s, but is not limited to these.

[0173] The inventors identified that the thermal conductivity is affected by the combination of the porous material and the liquid contained within it. The thermal conductivity of a mixture of a porous material and a liquid is λ M Increasing this can be detrimental to the proper operation of the vaporization system.

[0174] The simulation results are shown in Figure 3. Figure 3 shows (a) the thermal conductivity (λ) of the porous material and the liquid mixture as a function of the time to boiling. M (b) Increasing the thermal conductivity of the porous material and liquid combination (λ) for the energy required per unit of smoke extraction M (c) to increase the thermal conductivity of the porous material and liquid combination (λ) for thermal efficiency. MThis includes graphs showing the modeled effects of increasing the ) ). In the model that generated the graphs in Figure 3, the supplied power was adjusted to ensure a constant liquid throughput of 0.2 ml / min through the porous material. When the thermal conductivity of the porous material and liquid combination is increased, more energy diffuses through it. As shown in Figure 3(a), increasing the thermal conductivity of the porous material and liquid combination increases the time it takes for the liquid to reach its boiling point. As shown in Figure 3(b), increasing the thermal conductivity of the porous material and liquid combination increases the energy required per unit of vapor extraction. As shown in Figure 3(c), increasing the thermal conductivity of the porous material and liquid combination directly affects energy efficiency (i.e., the ratio of energy used for the actual vaporization of the liquid to the energy wasted in the mixture).

[0175] A mixture with a thermal conductivity of 0.225 watts / meter-Kelvin yielded an energy efficiency of 67 percent, but at thermal conductivity higher than 1 watts / meter-Kelvin, the energy efficiency decreased by less than 50 percent. Therefore, the inventors identified that porous materials and liquids can be designed to ensure the lowest possible thermal conductivity in order to increase energy efficiency.

[0176] The inventors also identified that the power density of the heating element affects its performance. For a heated surface on a combination of a porous material and a liquid, the simulation trends are provided in Figure 4, where the porous material and the liquid have fixed thermal conductivity. As shown in Figure 4(a), the time required to reach boiling decreases as the power density of the heating element increases. To reach boiling during fuming, a minimum power density is required to define a threshold Th. The simulations performed define the minimum power density required to ensure boiling of the liquid after 3 seconds, which is the duration of fuming by the Cholesterol method. This threshold depends, among other things, on the surface of the heated area and the thermal properties of the porous material and the liquid. As shown in Figure 4(b), very low throughput is obtained at threshold Th. Beyond threshold Th, throughput increases almost linearly with the supplied power density.

[0177] To ensure a usable throughput of 0.2 ml / min (equivalent to 3.3 μl / second or 10 μl / smoke inhalation per 3 seconds), a minimum of 25 watts / cm² is required. 2 The power density was simulated. In this simulation, each was 10 watts / cm². 2 The power delivers 7.5 joules per fumes, and once throughput is established, approximately 6 joules of fixed energy are wasted heating the porous body, with the remaining portion of the supplied energy delivered to vaporize the liquid. As a result, thermal efficiency increases with power density, as shown in Figure 4(c). Therefore, to maximize thermal efficiency, the vaporization surface area should be kept as small as possible with a heater delivering high power. This increases the liquid flow velocity within the porous body, which reduces heat loss within the porous body according to equation (2) (u L (The higher the temperature, the faster T(z) decreases.) However, this is limited by the liquid properties (surface tension, viscosity) and the throughput (porosity) that the porous material can accommodate. If insufficient liquid is supplied to the heating element, the heating element may overheat and eventually break.

[0178] In a model where the 0.5 mm heating side of the porous material is used as a heater with a power supply of 6.25 watts (i.e., bulk heating), the boiling point of 250 degrees Celsius is reached approximately 1.5 seconds later than with surface heating (Equation 1), i.e., 0.5 to 1.0 seconds later. This delay is due to the high energy required (and wasted) to heat a large amount of the porous material. The energy delivered during fumes is 19 joules (6.25 watts × 3 seconds), but the simulation is performed for a 5 × 5 mm layer. 2 It was shown that 14 joules are required to heat a 1 mm thick slice of porous material to 250 degrees Celsius. This energy is wasted and reduces the thermal efficiency of the vaporization system. Therefore, by ensuring that only the surface of the porous material is heated, for example by using an insulating layer, heat diffusion into the porous material is minimized and energy loss is reduced.

[0179] Figures 5(a) and 5(b) are schematic diagrams showing the current 109 flowing through the porous heating element 110, where (a) shows the case without defects and (b) shows the case with defects 108. In this case, the heating element 110 forms a film across the insulation layer 120. The porous heating element has advantages as a parallel track portion heating element as described in relation to Figures 6(a) to (c).

[0180] Generally, the beginning of a heater track failure is accompanied by an increase in local resistance. In the case of a single narrow track design, such as those present in existing meanders, the increase in local resistance leads to more power dissipation, further increasing resistance to failure, i.e., positive feedback.

[0181] The heater assemblies in Figures 5(a) and 5(b) avoid the effects of increased resistance by allowing the current flow to redistribute and avoiding the area of ​​increased resistance. Specifically, as illustrated in Figure 5(a), when a voltage is applied across the heating element, current flows within the heating element. Under normal (undamaged) heating conditions, the current flows in parallel within the heating element. In the case of damage to the heater film, indicated by defect 108 in Figure 5(b), the local resistance increases in the damaged area. This increase in local resistance pushes the current away from the damaged area and allows it to flow along the path of least resistance, avoiding positive feedback that would lead to heater failure. Because the heater failure is localized (unlike in the case of a single narrow heating track), the overall operation of the heater is preserved, and therefore its lifespan is increased.

[0182] Referring to Figures 6(a) to 6(c), schematic diagrams of different heating elements 110 for an aerosol generation system are shown. Each heating element 110 comprises multiple tracks or track sections 117 electrically arranged in parallel. By being electrically arranged in parallel, the current flow is divided into separate parallel channels. The channels are then recombined.

[0183] In the heating elements 110 shown in Figures 6(a) to 6(c), each heating element 110 includes a first connection pad 113 and a second connection pad 114. The first connection pad 113 and the second connection pad 114 are configured to allow connection to an external circuit. An opening or a number of openings 115 within the heating element 110 isolates each track 117. Each heating element 110 includes a branching section where the current is split from the first connection pad 113 to the track 117 which defines an electrically parallel path. Each heating element 110 includes a merging section where the current is combined from the track 117 which defines an electrically parallel path into the second connection pad 114.

[0184] Various different arrangements of electrically arranged tracks or track sections are possible. In Figure 6(a), four tracks 117 are separated by three openings 115 to define four electrically parallel paths. In Figure 6(b), six track sections 117 are separated by one opening 115 to define two electrically parallel paths. In Figure 6(b), each electrically parallel path defines a meandering path between a first connection pad 113 and a second connection pad 114. In Figure 6(c), eight track sections 117 are separated by four openings 115 to define four pairs of electrically parallel paths. Each pair of electrically parallel paths in Figure 6(c) is separated by an intermediate connection 116, three of which are shown in Figure 6(c).

[0185] By electrically arranging tracks or track sections in parallel, if one track section is faulty, the current can be redistributed and can still flow through the heating element 110, i.e., the electrical connection between the first connecting pad 113 and the second connecting pad 114 is not broken. This has the advantage of increasing the number of times the heater can be sucked up before it completely fails, potentially extending the heater's lifespan to the lifespan of the device. In contrast, in a simple meandering heater that defines a single electrical path between the first connecting pad 113 and the second connecting pad 114, if a part of the meandering heating element breaks, the heating element stops working due to an increase in local resistance at the point of breakage or fault. A fault in a simple meandering heater causes an increase in local resistance. An increase in local resistance causes an increase in power dissipation. Increased power dissipation then increases resistance until it breaks.

[0186] The inventors also identified that parallel tracks or track sections, electrically arranged in parallel as described with reference to Figures 6(a)-(c), have a surprising additional advantage. In such arrangements, if one track section fails, the heating element can still operate and, for an initial transient period, operate in a favorable manner because the failure of one track or track section results in a higher energy density for the remaining tracks or track sections. In such cases, the same power is still provided, but throughput increases in a smaller area. While such failures, which cause an increase in current on the undamaged tracks or track sections, may ultimately degrade the user experience, the device or cartridge may include a mechanism to warn the user of the potential for future degradation of the heater assembly's optimal performance.

[0187] These mechanisms depend on the following principles. The total electrical resistance of the heating element depends on the following factors: 1) Number of parallel heating tracks (more parallel tracks reduce total resistance), 2) Cross-sectional area (width or thickness (or width and thickness)) of parallel heating tracks (higher cross-sectional area leads to lower resistance), 3) Length of parallel heating tracks (longer tracks have higher resistance), 4) If the heating element is porous, adjust the porosity of the heating element (the higher the porosity, the greater the resistance). 5) A specific chemical or material composition (e.g., an alloy due to doping).

[0188] At least two adjacent tracks or sections of a track have currents flowing in the same direction R i The overall total heating element resistance R of the arrangement of multiple heating tracks or track sections (i) arranged in parallel so as to flow through them. tot This is shown in Equation 4.

number

[0189] In the formula, n is the total number of heating tracks electrically connected in parallel.

[0190] The behavior of a parallel track heating element when one heating track fails can be considered by referring to a heating element having four parallel heating tracks, for example, as shown in Figure 6(a). Each heating track has a resistance of 3 ohms. The total resistance of the heating element is 0.75 ohms, which is calculated using Equation 4.

[0191] When one heating track begins to fail, the resistance of the failed heating track increases. The total resistance of the heating element also begins to increase, after initially having a linear relationship with the resistance of the failed heating track. However, as the resistance of the heating tracks continues to increase, the resistance of the heating element becomes asymmetrical to a constant resistance value. At this constant resistance value, the effect of the failed heating track on the resistance of the heating element is minimized. In this embodiment, where each undamaged heating track has a resistance of 3 ohms, if the failed track can be considered an open circuit (i.e., no more current can flow through it), the total resistance of the heating element eventually approaches 1 ohm. When one track fails in this embodiment, only three tracks remain to calculate the total resistance of the heating element.

[0192] To account for the behavior of these heating elements, a supply voltage of 3.5 volts and a target power of 5.5 watts are considered. In this example, the undamaged parallel heating track remains at an initial resistance of 3 ohms. In the faulty track, the total maximum current decreases with increasing resistance. In the faulty track, the current decreases to zero upon breakage. The current through the undamaged parallel track becomes substantially constant as the resistance of the faulty track increases (assuming resistance changes due to temperature rise are ignored).

[0193] Similar behavior is observed with respect to maximum heating power generation. When a heating track fails, the total power generated decreases. However, in this embodiment, the maximum power remains above the 5.5 watt target even when one of the heating tracks fails.

[0194] In contrast to the heater film schematically illustrated in Figures 5(a) and 5(b), the increase in the overall heating resistance of a parallel track heating element can be monitored by a control electronic circuit. In a heater film such as the films in Figures 5(a) and 5(b), the current density (perpendicular to the flow of current) at both ends of the heater film increases in the damaged area, generating more power and raising the local temperature, so the damaged area 108 may expand over time until failure occurs. This locally increases the resistance of the heater film, causing the temperature to rise further and leading to failure (i.e., positive feedback). In the parallel track heating element, in contrast, the increase in the overall heating resistance can be monitored by a control electronic circuit. The device or system may be configured to communicate to the user through a user interface that the device or system should replace the heater assembly when a predetermined threshold is reached.

[0195] The device or cartridge may also be configured to extend the lifespan of the parallel track heating elements. The aerosol generator or system may include a control circuit. The control circuit may be configured to adjust the power supplied to the heater after detecting a failure in a heating track, for example, by a feedback loop. The control circuit may be configured to control the power supplied to the heater by providing a pulse-width modulation ("PWM") signal. The control circuit may adjust the power supplied to the heater by adjusting the load cycle of the pulse-width modulation signal. In one embodiment, the control circuit may be configured to have a load cycle of 33.7 percent when the heating tracks are in normal condition. The load cycle may increase to 44.9 percent when one of the heating tracks fails. When one of the heating tracks fails, the power density (heating power generated by the surface area) increases, improving the thermal efficiency of the heater body. Thus, the proper operation of the heater is not jeopardized by one failed heating track. A similar result occurs when a second heating track fails. The control circuit may be configured to further increase the load cycle (to 67.4 percent in this embodiment). Therefore, a heating element with four parallel heating tracks can still operate at its nominal 5.5 watts even if two of these heating tracks fail, because the load cycle remains below 100 percent.

[0196] The control circuit may be configured to evaluate the condition of the heating elements (i.e., the number of failed heating tracks) based on the change in the nominal total resistance of the heating elements when a parallel heating track fails. The control circuit may also be configured to inform the user that the device should replace the heater assembly after a predetermined number of heating tracks have failed.

[0197] The heating element in Figures 6(a) to 6(c) comprises multiple tracks or track portions 117 arranged at distances 118, 119 between at least two of the multiple tracks or track portions 117 within a range of 150 to 300 micrometers. This has the advantage of providing particularly effective heating of the substrate with the heating element 110 while limiting heat loss through the porous body 130.

[0198] Referring to Figures 7(a) and 7(b), schematic diagrams of the current flow 109 around the corners of the heating element track are shown.

[0199] Figure 7(a) is a schematic diagram of current flow 109 around a well-known heating element, where the track portion defines a path with a bend, and the inner end of the bend has a sharp corner. In such a track, the current flow indicated by arrow 109 following the path of least resistance is concentrated (i.e., there is an increase in current density). This concentration occurs at the inner edge of the corner. Current concentration can increase the local temperature, which can lead to the formation of a hot spot at the corner. Hot spots are undesirable because they can affect the efficiency and reliability of the heating element. Hot spots occur despite the possibility that the local resistivity of the heater track material may increase due to the local increase in temperature (directing the current to flow through the path of lower resistance).

[0200] Figure 7(b) is a schematic diagram of the current flow 109 around a heating element, where the track portion 117 defines a path with bends, and the inner end of the bend is curved. In such a track 117, the current flow 109 does not form localized hot spots.

[0201] In contrast to the track shape shown in Figure 7(a), the current flow 109 in a smoother, curved section of the track 117, as shown in Figure 7(b), remains more evenly distributed across the heating track 117, as indicated by the dashed arrows 109. The current flow 109 is guided to flow more evenly to avoid current concentration at any point. This limits the generation of hot spots. The heating track 117 may have a resistivity gradient perpendicular to the current flow at the corner, such that the resistivity is higher in the inner part of the corner and lower in the outer part of the corner. Such a gradient is beneficial in offsetting localized high current densities and reducing the generation of hot spots.

[0202] Referring to Figure 8, a heater assembly 200 is shown, which comprises a heating element 204 for vaporizing a liquid aerosol forming substrate and a porous body 202 for supplying the liquid aerosol forming substrate from a storage section or liquid storage section (not shown) to the heating element. The porous body 202 has a liquid absorption surface (not shown) and a heating surface 202a. The heating element 204 is disposed on the heating surface 202a of the porous body 202.

[0203] The heating element 204 is formed from a layer of conductive material so that an electric current can pass through it and heat it by resistance heating or Joule heating. The heating element 204 is also fluid permeable and porous so that vapor can pass through it from the heating surface 202a of the porous body 202. Thus, in the heater assembly 200 of Figure 8, vapor emission occurs through the heating element 204. The heating element 204 may comprise a thin metal layer or film having pores that pass through the thickness of the layer or film. Alternatively, the heating element may comprise a metal foam having interconnected open pores that pass through the thickness of the foam. In this example, the porous body 202 comprises a porous ceramic body formed from a suitable ceramic material such as Al2O3. Furthermore, the heating element 204 is deposited on the porous ceramic body 202 using a suitable physical or chemical vapor deposition process.

[0204] The heater assembly 200 further comprises electrical contacts 206 electrically connected to the heating element. The electrical contacts 206 are located on the heating surface 202a and at or near both ends of the heating surface 202a. The electrical contacts 206 are located on top of the insulating layer that is placed between the heating surface 202a and the heating element 204. The heating element 204 extends between the electrical contacts 206. The electrical contacts 206 are arranged to be connected to a control circuit for controlling the power supply to the heating element. The electrical contacts 206 are formed from a material that is more conductive than the heating element, such as copper, gold, or zinc, but other suitable materials may be used. This prevents the generation of excess waste heat within the electrical contacts.

[0205] Figure 9 shows a schematic cross-sectional view of the heater assembly 200 of Figure 8. For clarity and simplification, features are not depicted to scale. The liquid absorption surface 202b is shown as the underside of the porous body 202 in Figure 9, and the heating surface 202a is shown as the underside of the porous body 202, but it should be understood that the orientation of these surfaces may differ during use or when the heater assembly 200 is installed in an aerosol generator. Liquid stored in the liquid storage section or liquid storage portion (not shown) comes into contact with the liquid absorption surface 202b and is transported through the porous body 202 to the heating surface 202a, as indicated by arrow E in Figure 9. The porous heating element 204 is positioned on the heating surface 202a of the porous body 202 and heats the liquid aerosol-forming substrate being transported to it so that the liquid aerosol-forming substrate boils and generates steam. The porous heating element 204 has multiple pores that extend from the heating surface 202a through the thickness of the heating element to the outside of the heater assembly 200.

[0206] Because the heating element 204 is porous, steam generated during heating of the heating element 204 can pass through the pores of the heating element 204 and be released from the heated surface 202a, as indicated by arrow F in Figure 9. The heating element does not have an impermeable section to prevent steam release and cause steam pressure buildup beneath the heating element. This reduces the rate of steam release from the heating element 204 compared to conventional impermeable track heating elements. Simulations show that the average steam release rate from the heated surface 202a is 0.1 meters / second at a power of 6.3 watts. Such a low steam release rate means that the steam can be easily carried by the airflow in the airflow path without colliding with the inner walls of the airflow path and without causing condensation. As indicated by arrow F, the average steam release direction is substantially perpendicular to the heated surface 202a of the porous body 202, and the steam is consistently released across the surface of the heating element.

[0207] Figure 10 is a schematic diagram of the interior of an aerosol generating system 800 according to an embodiment of the present disclosure. The aerosol generating system 800 comprises two main components: a cartridge 801 and a main body or aerosol generating device 900. The cartridge 801 is detachably connected to the aerosol generating device 900. In this embodiment, the aerosol generating device 900 comprises a device housing 901 containing a power source in the form of a battery 902, which is a rechargeable lithium-ion battery, and a control circuit 903. The aerosol generating system 800 is portable and has a size comparable to a conventional cigar or cigarette. A mouthpiece is located at the mouth end of the cartridge 801.

[0208] The cartridge 801 comprises a cartridge housing that contains a heater assembly 100 and a liquid storage section or liquid storage portion 803 for holding a liquid aerosol forming substrate. The liquid aerosol forming substrate is conveyed downward from the liquid absorption surface 134 through the porous material to the heating element, and the vaporized aerosol forming substrate is released from the heating surface 133 when power is supplied to the heating element.

[0209] The cartridge 801 includes one or more air intake ports 804 formed within the cartridge housing 805 at positions along the length of the cartridge 801. The aerosol outlet 806 is located within the mouthpiece at the mouth end of the cartridge 801. The one or more air intake ports 804 are in fluid communication with the aerosol outlet 806 to define the airflow path through the cartridge 801 of the aerosol generating system 800. The airflow path flows from the one or more air intake ports 804 to the heater assembly 100 in the airflow channel. The heater assembly 100 is arranged to be in fluid communication with the airflow path in the airflow channel. Air enters the one or more air intake ports 804 and flows through the airflow channel, passing through the heater assembly 100 in the mean airflow direction.

[0210] In the embodiment shown in Figure 10, the liquid storage section 803 has an annular cross-section and is arranged around a centrally sealed aerosol channel 807. When the airflow path reaches the heater assembly 100, it is redirected upward around the side of the heater assembly 100 and flows through the aerosol channel 807 to the aerosol outlet 806.

[0211] The aerosol generating system 800 is configured so that a user can inhale or smoke the mouthpiece of a cartridge, thereby drawing an aerosol into their mouth through an aerosol outlet 806. During operation, when a user smokes the mouthpiece, air is drawn through one or more air intake ports 804, along an airflow path through an airflow channel, through the heater assembly 100, and around it, along an airflow path through an aerosol channel 807, to the aerosol outlet 806. The control circuit 903 controls the supply of power from the battery 902 to the cartridge 801 when the system is started. This then controls the amount and characteristics of the vapor produced by the heater assembly 100. The control circuit 903 includes an airflow sensor (not shown) that supplies power to the heater assembly 100 when a user is detected by the airflow sensor. This type of control device is well established in aerosol generating systems such as inhalers and e-cigarettes. When the user inhales vapor from the mouthpiece of cartridge 801, the heater assembly 100 is activated, generating vapor, which is carried into the airflow path. The vapor cools in the airflow path, forming an aerosol, which is then inhaled into the user's mouth through the aerosol outlet 806.

[0212] Figure 11 is a schematic cross-sectional view of a portion of an aerosol generating system 300 according to another embodiment of the present disclosure, showing the arrangement of the heater assembly 300 with respect to the airflow path 320 within the aerosol generating system 300. For simplification, other components of the aerosol generating system are omitted from Figure 11. The heater assembly 200 in Figure 11 is identical to the heater assembly 200 in Figures 8 and 9. The aerosol generating system 300 includes a liquid storage portion 322 that holds a liquid aerosol-forming substrate in contact with the liquid-absorbing surface 202b of the porous body 202. The liquid aerosol-forming substrate is transported from the liquid storage portion 322 through the porous body 202 to the heated surface 202a, as indicated by arrow E. The vaporized aerosol-forming substrate is released from the heated surface 202a through a porous heating element 204. As indicated by arrow F, the mean vapor release direction is substantially perpendicular to the heated surface 202a of the porous body 202.

[0213] In the embodiment shown in Figure 11, the heater assembly 200 is positioned below or to the side of one side of the airflow channel or path 320, which is defined by the airflow channel wall 324. As seen in Figure 11, the left end of the visible portion of the airflow path 320 receives airflow from an air intake (not shown), and the right end of the visible portion of the airflow path delivers airflow to an aerosol outlet (not shown). The heating surface 202a of the porous body 202 is positioned in parallel with the airflow path 320 and faces the airflow path 320. The heater assembly 200 is in fluid communication with the airflow path, as indicated by arrow G, so that the airflow in the airflow path flows through the heater assembly 200 in the mean airflow direction. The heater assembly 200 and the airflow path 320 are arranged such that the angle θ between the mean vapor discharge direction F and the mean airflow direction G is approximately 90 degrees, that is, an angle θ substantially perpendicular to the mean airflow direction G. The mean vapor discharge direction F has no velocity or directional component opposite to the mean airflow direction G, and therefore the loss of airflow momentum is reduced. This reduces the tendency for recirculation and turbulence to occur within the airflow path 320 and makes it less likely for vapor to collide with the inner surface of the airflow channel wall 324.

[0214] Figure 12 is a schematic cross-sectional view of a portion of an aerosol generating system 400 according to another embodiment of the present disclosure, showing an alternative arrangement of the heater assembly 200 with respect to an airflow path 420 within the aerosol generating system 400. For simplification, other components of the aerosol generating system are omitted from Figure 12. The heater assembly 200 in Figure 12 is identical to the heater assembly 200 in Figures 8 and 9. The aerosol generating system 400 includes a liquid storage portion 422 that holds a liquid aerosol-forming substrate in contact with the liquid-absorbing surface 202b of the porous body 202. The liquid aerosol-forming substrate is transported from the liquid storage portion 422 through the porous body 202 to the heated surface 202a, as indicated by arrow E. The vaporized aerosol-forming substrate is released from the heated surface 202a through a porous heating element 204. As indicated by arrow F, the mean vapor release direction is substantially perpendicular to the heated surface 202a of the porous body 202.

[0215] In the embodiment shown in Figure 12, the airflow channel or path 420 is divided into first and second airflow path sections 420a and 420b that pass through both sides of the heater assembly 200. The first airflow path section 420a and the second airflow path section 420b are combined into a third airflow path section 420c downstream of the heater assembly 200. The first airflow path section 420a and the second airflow path section 420b receive airflow from one or more air intakes (not shown), and the third airflow path section 420c delivers airflow to an aerosol outlet (not shown). The airflow path 420 is defined by the airflow channel wall 424. The heating surface 202a of the porous body 202 is positioned substantially perpendicular to the airflow path 420 and faces downstream of the airflow path 420. The heater assembly 200 is in fluid communication with the airflow path, as indicated by arrow G, such that the airflow within the airflow path flows through the heater assembly 200 in the direction of the mean airflow.

[0216] The heater assembly 200 and the airflow path 220 are arranged such that the angle θ between the mean vapor release direction F and the mean airflow direction G is less than 90 degrees. Upstream of the heated surface 202a of the porous body 202, the mean airflow direction G passing through the heater assembly 200 is substantially the same as the vapor release direction F. Along the airflow path 420 corresponding to the heated surface 202a, the airflow path 420 begins to narrow inward or taper, and at that point, the mean airflow direction G passing through the heater assembly 200 changes to an angle θ of approximately 45 degrees with respect to the vapor release direction F. Downstream of the heated surface 202a of the porous body 202 in the third airflow path section 420c, the mean airflow direction G of the combined airflow is again substantially the same as the vapor release direction F. It will be understood that the narrowing or taper of the airflow path 420 may be omitted. In that case, the average airflow direction G passing through the heater assembly 100 is substantially the same as the steam discharge direction F.

[0217] Figures 13 and 14 show schematic diagrams of an embodiment of a heater assembly 500 for an aerosol generation system. The heater assembly includes a heating element 510 and a porous body 520.

[0218] The heating element 510 is configured to vaporize an aerosol-forming substrate, such as a liquid aerosol-forming substrate, to form an aerosol. The heating element 510 is configured to convert electrical energy into thermal energy through the material resistance of the heating element 510 to electric current.

[0219] The porous body 520 is configured to transport the liquid aerosol-forming substrate to the heating element 510. In other words, the porous body 520 supplies the liquid aerosol-forming substrate to the heating element 510.

[0220] The porous body 520 has a first end face and an opposing second end face. The first end face is the liquid absorption surface 530, and the second end face is the heating surface 540. In this embodiment, both the liquid absorption surface 530 and the heating surface 540 are substantially flat surfaces. The porous body 520 also has a plurality of sides extending between the liquid absorption surface 530 and the heating surface 540.

[0221] In this embodiment, as will be discussed in more detail below, the porous body 520 has a first side surface 550 facing the second side surface 560, and a third side surface 570 facing the fourth side surface 580.

[0222] The porous body 520 contains a plurality of pores. The plurality of pores are interconnected to provide a fluid path through the porous body 520 for the liquid aerosol-forming substrate from the liquid absorption surface 530 to the heating surface 140. The porous body 520 is formed from a material that does not chemically interact with the liquid aerosol-forming substrate. In this embodiment, the porous body 520 is a porous ceramic body and may be formed from, for example, Ca2SiO3 or SiO2 (or Ca2SiO3 and SiO2). In another embodiment, the porous body 520 may be, for example, a porous glass body.

[0223] The heating element 510 is located on the insulating layer 590 and on the porous body 520. In the embodiments shown in Figures 13 and 14, the heating element 510 is a porous film that extends substantially over all heating surfaces 540.

[0224] The liquid-absorbing surface 530 of the porous body 520 has a different region from the heated surface 540 of the porous body 520. Specifically, in the embodiments shown in Figures 13 and 14, the area of ​​the heated surface 540 is smaller than the area of ​​the liquid-absorbing surface 530.

[0225] In the embodiments of Figures 13 and 14, the length of the heating surface 540 is shorter than the length of the liquid absorption surface 530, so the heating surface 540 has a smaller area than the liquid absorption surface 530. Furthermore, in another embodiment, the width of the heating surface 540 is smaller than the width of the liquid absorption surface 530, so the heating surface 540 may have a smaller area than the liquid absorption surface 530.

[0226] In the embodiments of Figures 13 and 14, the porous body 520 is formed as a trapezoidal prism. With the porous body 520 having a trapezoidal prism shape, the first side surface 550 and the second side surface 560 are both trapezoidal, particularly isosceles trapezoidal, the third side surface 570 and the fourth side surface 580 are both rectangular, and the liquid absorption surface 530 and the heating surface 540 are both rectangular. In another embodiment, the liquid absorption surface 530 and the heating surface 540 may have a square shape.

[0227] The porous body 520 tapers from the liquid-absorbing surface 530 towards the heating surface 540. In other words, the cross-sectional area of ​​the porous body 520 gradually decreases from the liquid-absorbing surface 530 towards the heating surface 540. In the embodiments of Figures 13 and 14, the length of the porous body 520 decreases and tapers from the liquid-absorbing surface 530 towards the heating surface 540.

[0228] The heater assembly 500 includes an insulation layer 590.

[0229] The heating element 510 is positioned along the heating surface of the insulation layer 590. The heating element 510 is in direct contact with the insulation layer 590.

[0230] The insulation layer 590 is arranged to enhance the insulation between the heating element 510 and the porous ceramic body 520. The insulation layer 590 extends over at least a portion of the heating element 510 and is arranged to insulate the heating element 510 from the porous ceramic body 520. The insulation layer 590 is configured to reduce heat dissipation through the porous ceramic body 520 in order to improve energy efficiency by reducing energy loss.

[0231] Figure 15 shows a heater assembly 600 for use in an aerosol generation system. The heater assembly 600 includes a heating element 610 for vaporizing a liquid aerosol-forming substrate. The heater assembly 600 includes a porous ceramic body 620 for transporting the liquid aerosol-forming substrate to the heating element 610. The porous ceramic body 620 has a liquid absorption surface 621 and an opposing heating surface 622. The heating element 610 is located on an insulating layer 630. The insulating layer 630 is located on the heating surface 622 of the porous ceramic body 620.

[0232] The heated surface 622 of the porous ceramic body 620 is curved. In particular, the heated surface 622 of the porous ceramic body 620 is curved in a convex shape in a single transverse direction (first transverse direction).

[0233] The porous body 620 has a prismatic shape. When viewing a cross-section of the porous body 620 in the direction of its major axis perpendicular to the curvature direction, the heated surface 622 of the porous body 620 is shown as a circular arc. The porous body 620 has two symmetrical planes in the direction of its major axis.

[0234] The heating surface 620 of the porous ceramic body 620 has a first transverse width 623 that is substantially the same as the first transverse width of the porous ceramic body 620 and substantially the same as the first transverse width of the heater assembly 600. The heating surface 620 of the porous ceramic body 620 has a width of approximately 5 millimeters in the first transverse direction.

[0235] The heated surface 620 of the porous ceramic body 620 has a length or thickness of approximately 1 millimeter. The porous ceramic body 620 has a length or thickness of approximately 3 millimeters.

[0236] The heated surface 620 of the porous ceramic body has a radius of curvature of approximately 3.6 millimeters. The heated surface 620 of the porous ceramic body has a surface area of ​​approximately 28 square millimeters.

[0237] The porous body 620 has four longitudinal surfaces or side walls extending from the liquid-absorbing surface 621 to the heating surface 622. The four side walls are substantially perpendicular to the liquid-absorbing surface 621, which is substantially flat. The liquid-absorbing surface 621 has a square shape.

[0238] The heating element 610 is a resistance heating element 610.

[0239] The heating element 610 is curved. In particular, the curvature of the heating element is substantially the same as the curvature of the heating surface 622 of the porous ceramic body 120. Thus, the heating element 610 is also curved convexly in a single transverse direction.

[0240] The heating element 610 is located directly on the heating surface 622 of the porous ceramic body 620. The heating element 610 extends over most of the heating surface 622 of the porous ceramic body 620. The entire heating element 610 is substantially in contact with the heating surface 622 of the porous ceramic body 620.

[0241] The heater assembly 600 includes an insulating layer 630 located between the porous ceramic body 620 and the heating element 610. The insulating layer 630 is in direct contact with both the heating surface 622 of the porous ceramic body 620 and the heating element 610. The insulating layer 620 substantially covers the entire heating surface 622 of the porous ceramic body 620.

[0242] The insulation layer 630 is arranged to enhance the insulation between the heating element 610 and the porous ceramic body 620. The insulation layer 630 is configured to reduce heat dissipation through the porous ceramic body 620 in order to improve the energy efficiency of the heater assembly 600 by reducing energy loss.

[0243] The insulation layer 630 is curved. In particular, the insulation layer 630 is curved convexly in a single transverse direction (first transverse direction). The curvature of the insulation layer 630 corresponds to the curvature of the heated surface 622 of the porous ceramic body 620.

[0244] In particular, the thermal insulation layer 620 has a first end face and an opposing second end face. The first end face is a liquid absorption surface 631, and the second end face is a heating surface 632. Both the liquid absorption surface 631 of the thermal insulation layer 630 and the heating surface 632 of the thermal insulation layer are convex in the first transverse direction with a curvature corresponding to the curvature of the heating surface 622 of the porous ceramic body 620.

[0245] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers representing amounts, quantities, proportions, etc., are understood to be modified in all cases by the term “approximately.” Furthermore, all ranges include the disclosed maximum and minimum values, as well as any intermediate ranges contained within them, whether or not they are specifically enumerated herein. Thus, in this context, the number A is understood as A ± 10 percent (10%). In this context, the number A may be considered to include a number that falls within the general standard error of the measurement of the characteristic that A modifies. In some examples used in the appended claims, the number A may deviate by the percentages listed above, as long as the amount of deviation of A does not substantially affect the basic and novel characteristics of the invention described in the claims. Furthermore, all ranges include the disclosed maximum and minimum values, as well as any intermediate ranges contained within them, whether or not they are specifically enumerated herein.

Claims

1. A heater assembly for an aerosol generator, wherein the heater assembly is A heat-generating element for vaporizing the liquid aerosol-forming substrate, A porous body for transporting the liquid aerosol forming substrate to the heating element, A thermal insulation layer having a lower thermal conductivity than the porous material, wherein the thermal insulation layer is disposed between the porous material and the heating element, and is in contact with the porous material and the heating element, and is configured to reduce heat transfer from the heating element to the porous material, The porous body includes a porous ceramic body or a porous glass body, A heater assembly in which the heating element forms a film across the heat insulating layer.

2. The heater assembly according to claim 1, wherein the insulating layer includes an insulating material, and the insulating material has a lower thermal conductivity than the porous body.

3. The heater assembly according to claim 1 or claim 2, wherein the insulating layer comprises a material having a thermal conductivity of less than 40 watts / meter-Kelvin.

4. The heater assembly according to any one of claims 1 to 3, wherein the insulating layer comprises a material having a thermal conductivity of less than 10 watts / meter-Kelvin.

5. The heater assembly according to any one of claims 1 to 4, wherein the insulating layer includes an insulating material, and the insulating material has a higher porosity than the porous body.

6. The heater assembly according to any one of claims 1 to 5, wherein the insulating layer extends throughout the space between the porous body and the heating element.

7. The heater assembly according to any one of claims 1 to 6, wherein the heat insulating layer comprises one or more of alumina, zirconia, zirconia containing magnesium oxide, glass ceramic, quartz, and porous polymer.

8. The heater assembly according to any one of claims 1 to 7, wherein the heat insulating layer has a thickness of 0.1 mm to 2 mm, preferably 0.5 mm to 1.5 mm.

9. The heater assembly according to any one of claims 1 to 8, wherein the heating element is a porous heating element.

10. The heater assembly according to any one of claims 1 to 9, wherein the heat insulating layer has a heating surface, and the heating element extends to cover the region of the heating surface of the heat insulating layer.

11. The heater assembly according to any one of claims 1 to 10, wherein the heating element comprises a plurality of tracks or track portions, wherein the distance between at least two of the plurality of tracks or track portions is within the range of 150 to 300 micrometers.

12. The heater assembly according to any one of claims 1 to 11, wherein the porous body includes an electrical insulating material.

13. The heater assembly according to any one of claims 1 to 12, wherein the heating element and the porous body are integrally formed.

14. The heater assembly according to any one of claims 1 to 13, wherein the heat insulating layer has a heating surface, the heating element is located on the heating surface of the heat insulating layer and bonded to the heating surface.

15. An aerosol generating system comprising a heater assembly according to any one of claims 1 to 14, wherein the heating element is fluid permeable such that vapor is released from the heater assembly in the average vapor discharge direction during use, The aerosol generating system further comprises an air intake and an aerosol outlet, the air intake and the aerosol outlet are in fluid communication, defining an airflow path through the aerosol generating system. An aerosol generating system in which the heater assembly is arranged in fluid communication with the airflow path such that air flows through the heater assembly in the mean airflow direction, and the heater assembly and the airflow path are arranged such that the angle between the mean vapor discharge direction and the mean airflow direction is less than 135 degrees.

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