Aerosol generating system and method for directing an airflow within an electrically heated aerosol generating system

Abstract

An aerosol-generating system comprises: a liquid storage portion including a container containing a liquid aerosol-forming substrate and defining an opening; and a heater assembly extending through the opening along a transverse plane. The heater assembly comprises at least one electrically operated heating element, and a first channel defines a first flow path for ambient air to impinge upon the heater assembly. In one embodiment, a portion of the first channel is arranged orthogonal to the transverse plane such that at least a portion of the first channel directs ambient air from outside the system to perpendicularly impinge upon a surface portion of the heating element, and subsequently conveys the ambient air to a downstream end.

Description

[0001] This application is a divisional application of an international application filed on December 14, 2015, with international application number PCT / EP2015 / 079623, national application number 201580064009.1, and entitled “Aerosol Generating System and Method for Guiding Airflow Inside an Electric Heating Aerosol Generating System”, which entered the Chinese national phase. Technical Field

[0002] The present invention relates to electrically heated aerosol generating systems, such as electrically heated smoking systems, and methods for directing an airflow within such systems. Background Art

[0003] Some aerosol-generating systems may include a battery and control electronics, a cartridge containing a supply of aerosol-forming substrate, and an electrically operated vaporizer. The substance is vaporized from the aerosol-forming substrate, for example, by a heater. When the user inhales (e.g., "draws") at the mouth end, an air flow is passed through the heater to entrain the vaporized liquid and direct it through the mouthpiece to the mouth end of the mouthpiece.

[0004] The flow air needs to be managed so that during each puff as much of the liquid vaporized by the heater as possible is carried away from the heating area for inhalation. The flow will further need to be managed to minimize the formation of droplets outside the desired inhalable range. Summary of the Invention

[0005] According to a first aspect, an electrically heated smoking system for generating an aerosol is provided. The heated smoking system utilizes a heater positioned relative to an airflow system having a downstream end and one or more channels for drawing in ambient air. Each of the one or more channels defines a respective flow path. A first flow path, defined by the first channels, directs air from outside the system so that the air impinges upon one or more electrical heating elements of the heater before being delivered to the downstream end. Air carried along each first flow path can be directed as ambient air at the heater without preheating, or can be subjected to a preheating step before being directed against and along the heater.

[0006] In some embodiments, the first flow path causes the air to initially impinge along a path substantially orthogonal to the plane in which the heater's electrical heating elements are arranged. This arrangement is advantageous because it has been found that a perpendicular impingement angle relative to the heater's geometric center promotes efficient steam entrainment. When multiple channels are used, the individual airflows can be combined at or before a point along a common orthogonal path. Alternatively, one or more airflows can be directed to impinge on the heater assembly at any angle so that the airflow impinges against and along a common plane passing through the one or more heating elements.

[0007] Steam in the heater zone is collected by air flowing through one or more channels and transported to the downstream end of the airflow system. As the steam condenses within the flowing air, droplets form, creating an aerosol. It has been found that ambient airflow impinging on the heating element at a 90-degree angle efficiently and effectively entrains steam, directing it toward the downstream "mouth" end of the system. The more aggressively the ambient airflow impinges on the heating element, the more efficient the steam is entrained and expelled. Specifically, if the ambient air impinges on the surface of the heating element at an angle normal to the geometric center of the heating element, uniform airflow within the heating element in a radially outward direction can be provided.

[0008] The volume of ambient air passing through the first and any other channels and perpendicularly impinging on the heating element can vary and be adapted, for example, to the type of heating element used or the amount of vaporised liquid available. For example, the volume of ambient air impinging on the heating element can be adapted to the total area effectively heated by the heating element.

[0009] In an embodiment, the heated air that contains steam that leaves the heater zone passes through cooling zone, and described zone intersects and is adjacent to the position that stores aerosol in the tube and forms matrix.Because the temperature of the tube surface in this area is lower than the air that contains steam, described adjacent relationship has significant cooling effect.When air passes through thin channel (setting its size and being arranged to be used for making the airflow interaction maximization in the tube surface), this effect is especially obvious.The result causes the supersaturated fast cooling of vaporized liquid in the air and promotes the formation of less aerosol droplet in turn.In certain embodiments, preferably during steam condensation, droplet size is remained in the inhalable range of 0.5 to 1 micron.

[0010] In some embodiments, a sharp bend (e.g., about 90 degrees) in the aerosol flow around the portion of the barrel containing the liquid matrix serves a supplemental droplet filtering function, where droplets exceeding the respirable range condense in the corners of the flow path and are not delivered to the downstream end.

[0011] Generally speaking, whenever the term 'about' is used in conjunction with a specific value in this application, it should be understood that the value following the term 'about' is not necessarily exactly the specific value due to technical considerations. However, the term 'about' used in conjunction with a specific value is always understood to include and also explicitly disclose the specific value following the term 'about'.

[0012] With respect to the orientation and position of the heater relative to the opening in the container containing the aerosol-generating liquid, the term "through" is intended to refer to an arrangement in which one or more heating elements, through which a common plane (e.g., a plane transverse to the container opening) passes, are located above or through at least a portion of the opening. In some embodiments, for example, the heater may completely cover the container opening, while in other embodiments, the heater may only partially cover the container opening. In still other embodiments, the heater may be positioned within the opening so that it extends through the entire opening on all sides, while in still other embodiments, the heater may be positioned so that it extends through a first pair of opposing side portions of the opening and not through a second pair of opposing side portions of the opening.

[0013] The terms 'upstream' and 'downstream' are used herein in view of the direction of the airflow in the system. The upstream and downstream ends of the system are defined relative to the airflow when a user draws on the proximal end or mouth end of an aerosol generating smoking article. Air is drawn into the system at the upstream end, passes through the system downstream and leaves the system at the proximal end or downstream end. As used herein, the terms 'proximal' and 'distal' refer to the position of an element relative to its orientation to or away from the user. Therefore, the proximal end of the mouthpiece of an aerosol generating system corresponds to the mouth end of the mouthpiece. Accordingly, the distal opening of the cartridge housing corresponds to the position of the opening arranged in the cartridge housing facing away from the user.

[0014] A heater for a smoking system in accordance with an embodiment of the present invention may, for example, be a fluid-permeable heating assembly comprising one or more electrically conductive heating elements. The one or more electrically conductive heating elements are sized and arranged to generate heat when an electric current is applied thereto. The fluid-permeable heating assembly is suitable for vaporizing different types of liquids in a cartridge. For example, the cartridge may contain a liquid, or a liquid containing a transport material such as a capillary material, such as a liquid aerosol-forming matrix. The transport material and the capillary material actively transport the liquid and are preferably oriented in the cartridge to transport the liquid to the heating element. In an embodiment, the one or more electrically conductive heating elements are heat-generating wires arranged near the liquid or near a capillary material containing the liquid, so that the heat generated by the heating element vaporizes the liquid. Preferably, the wire and the aerosol-forming matrix are arranged so that the liquid can flow into the voids of the wire structure by capillary action. The wire structure may also be in physical contact with the capillary material.

[0015] In an embodiment, the fluid permeable heating assembly includes one or more heating elements through which a common plane passes, so that the heater has a substantially flat orientation. The heating element can be, for example, a flat coil embedded in a porous ceramic or mesh heater, wherein the mesh or other filament structure is arranged above an opening in the heater. The fluid permeable heating assembly can, for example, include a conductive mesh or coil pattern printed on a heat-resistant carrier. The carrier can be, for example, ceramic, polyetheretherketone (PEEK), or other heat-resistant ceramics and polymers that do not thermally decompose and release volatile elements at temperatures below 200°C and preferably below 150°C.

[0016] The heater vaporizes liquid from a cartridge or cartridge housing comprising an aerosol-forming substrate. An aerosol-forming substrate is a substrate capable of releasing volatile compounds that can form an aerosol. The volatile compounds can be released by heating the aerosol-forming substrate. The aerosol-forming substrate can comprise a plant-based material. The aerosol-forming substrate can comprise tobacco. The aerosol-forming substrate can comprise a tobacco-containing material containing volatile tobacco flavor compounds, which is released from the aerosol-forming substrate when heated. Alternatively, the aerosol-forming substrate can comprise a non-tobacco-containing material. The aerosol-forming substrate can comprise a homogenized plant-based material. The aerosol-forming substrate can comprise a homogenized tobacco material. The aerosol-forming substrate can comprise at least one aerosol-forming agent. The aerosol-forming agent is any suitable known compound or mixture of compounds that, in use, contributes to forming a thick and stable aerosol and is substantially resistant to thermal degradation at the operating temperature of the system. Suitable aerosol formers are well known in the art and include, but are not limited to, polyols such as triethylene glycol, 1,3-butylene glycol, and glycerol; esters of polyols such as glycerol mono-, di-, or triacetate; and aliphatic esters of mono-, di-, or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Preferred aerosol formers are polyols or mixtures thereof such as triethylene glycol, 1,3-butylene glycol, and most preferably glycerol. The aerosol-forming matrix may include other additives and ingredients such as fragrances.

[0017] The aerosol-forming substrate can be delivered to the heating element via a capillary material in contact with or adjacent to the heating element. The capillary material can have a fibrous or sponge-like structure. Preferably, the capillary material comprises a bundle of capillaries. For example, the capillary material can include a plurality of fibers or threads or other fine-pored tubes. The fibers or threads can be generally aligned to deliver the liquid to the heating element. Alternatively, the capillary material can comprise a sponge-like or foam-like material. The structure of the capillary material forms a plurality of small pores or tubes through which the liquid can be transported by capillary action. The capillary material can comprise any suitable material or combination of materials. Examples of suitable materials include sponges or foams; ceramic or graphite-like materials in the form of fibers or sintered powders; foamed metals or plastic materials; fibrous materials, such as woven or extruded fibers, such as cellulose acetate, polyester or bonded polyolefins, polyethylene, terylene or polypropylene fibers, nylon fibers, or ceramics. The capillary material can have any suitable capillary properties and porosity to facilitate use with different liquid physical properties. Liquids have physical properties, including but not limited to viscosity, surface tension, density, thermal conductivity, boiling point, and vapor pressure, that cause the liquid to be transported through a capillary device by capillary action.

[0018] The capillary material may be in contact with the conductive filaments of the heater. The capillary material may extend into the spaces between the filaments. The heating element may draw the liquid aerosol-forming substrate into the spaces by capillary action. The capillary material may be in contact with the conductive filaments over substantially the entire extent of the opening in the heating element.

[0019] The heating element can be disposed in a heating assembly that includes a support element. The heating assembly can contain two or more different capillary materials, wherein a first capillary material in contact with the heating element has a higher thermal decomposition temperature, and a second capillary material in contact with the first capillary material but not in contact with the heating element has a lower thermal decomposition temperature. The first capillary material effectively acts as a spacer separating the heating element from the second capillary material, protecting the second capillary material from temperatures exceeding its thermal decomposition temperature. As used herein, 'thermal decomposition temperature' refers to the temperature at which a material begins to decompose and lose mass by producing gaseous byproducts. Advantageously, the second capillary material can occupy a larger volume than the first capillary material and can accommodate more aerosol-forming substrate than the first capillary material. The second capillary material can have better wicking properties than the first capillary material. The second capillary material can be cheaper or have a higher filling capacity than the first capillary material. The second capillary material can be polypropylene.

[0020] Flow path can be selected to reach desired result, for example, predetermined volume of air passes through one or more channels and impacts heater surface. For example, the length or diameter of the channel can be changed, for example, also reaching predetermined resistance to draw (RTD). Flow path is also selected according to the configuration and feature of the individual components of the aerosol generating smoking system and the smoking system. For example, aerosol can be generated at the proximal end or distal end of the cartridge housing containing an aerosol-forming substrate. Depending on the orientation of the cartridge in the aerosol generating smoking system, the open end of the cartridge housing is arranged to face the cigarette holder or is arranged to face away from the cigarette holder. Therefore, the heating element for heating the aerosol-forming substrate is arranged at the proximal end or distal end of the housing. Preferably, the liquid vaporizes at the open distal end of the cigarette holder, and the heating element is arranged between the cartridge and the cigarette holder.

[0021] In some embodiments, one or more heating elements are arranged at the open proximal end of the cartridge housing, such as to cover the proximal end of the cartridge (highest version). In the described embodiment, the first flow path and the first channel can be completely arranged in the cigarette holder of the smoking system, the first air inlet being arranged in the sidewall of the cigarette holder, and one or more outlets of the first channel being arranged in the proximal end or the mouth end of the cigarette holder. Optionally, other flow paths and channels are defined in the cigarette holder. The first channel and any other channels are arranged according to the position of the heating element of the smoking system. In an embodiment, for example, if the heating element is arranged at the open proximal end of the cartridge housing, such as to cover the proximal end of the cartridge (highest version), the channel can also be completely arranged in the cigarette holder so.

[0022] In the alternative embodiment that one or more heating elements are arranged at the open far-end of tube housing, flow path usually starts from another far-end position in smoking system, for example, is positioned at the far-end region of tube housing.For this purpose, the air inlet of each passage and first portion can be arranged in the main section of smoking system to define and be communicated with the first channel portion of the corresponding channel portion fluid defined in cigarette holder.Ambient air is subsequently introduced into system, passes through the heating element at the far-end of tube and entrains the steam that forms matrix by the aerosol in heating tube.Can subsequently along tube between tube housing and main housing, the air containing aerosol is directed to the downstream end of system, it mixes with the ambient air from the first flow path (before or after arriving downstream end) at described downstream end.

[0023] A single channel can be split into several channel portions downstream of the heating element, and several channel portions upstream of the heating element can be converged into a single channel that then impinges orthogonally on the geometric center of the heater. Alternatively, a first channel can be composed of several first partial channels, and a second channel can be composed of several second partial channels.

[0024] The flow path can provide multiple variations to supply ambient air to the heating element and transport aerosol away from the heating element and toward the downstream end of the system. For example, radial supply of ambient air is preferably combined with a large central extraction. Central supply of ambient air is preferably combined with radial distribution of air across the entire surface of the heating element, with circumferential delivery of the aerosol-laden air toward the downstream end. In the described embodiment, the flow path is combined to direct the ambient air to impinge on the heating element, for example, perpendicularly to the heating element, preferably toward the center of the heating element.

[0025] Airflow directed perpendicular to the central portion of the heating element exhibits improved aerosolization in terms of smaller particle size and a higher amount of total particulate matter present in the aerosol stream when compared to airflow impacting the surface at an angle greater than 0 and less than 90 degrees. This may be due to a lower level of eddy currents formed at the interface of the heater element and the airflow, improved aerosol production by maximizing the overall heater (e.g., portions outside the central portion of the heater element contribute to additional or higher amounts of aerosol), or due to a higher wicking effect based on the larger volume of air passing through the heating element.

[0026] A method for directing airflow to generate aerosol in an electrically heated smoking system comprises directing ambient air from outside the system perpendicular to a heating element and delivering heated air containing vapor to promote supersaturation of the vapor produced by heating a liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is further described with reference to the embodiments illustrated by the following drawings, in which:

[0028] Figure 1 An aerosol generating system using an air flow according to an embodiment consistent with the present invention is shown;

[0029] Figure 2 shows an aerosol generating system using an ambient air flow and a vapor-entrained air flow according to other embodiments consistent with the present invention;

[0030] Figure 3A shows an assembled form (in cross-section) of an aerosol generating system using an ambient air flow and a vapor-entrained air flow according to another embodiment consistent with the present invention;

[0031] Figure 3B show Figure 3A Exploded or unassembled form (in cross-section) of the embodiments;

[0032] Figure 4 Shows the cooling effect of different air flows on different heating elements;

[0033] Figure 5shows a temperature profile based on an exemplary flow impingement pattern and a substantially planar configuration of electrically powered heating wires forming a grid heater;

[0034] Figure 6 Display the temperature curve at the mouthpiece outlet;

[0035] Figure 7 Displays the average vapor saturation curve at the mouthpiece outlet;

[0036] Figure 8 Shown is the same heater configuration and applied power. Figure 1 and Figure 2 The air flow geometry at the mouthpiece outlet is the ratio of the droplet diameter;

[0037] Figures 9a, 9b show heating elements that may be used in a smoking system according to the present invention. DETAILED DESCRIPTION

[0038] Figure 1 , an embodiment of a cartridge 4 and a mouthpiece 1 for an aerosol-generating smoking system is shown in FIG. An elongated main housing 5 houses a cartridge having a tubular container 4 containing an aerosol-forming substrate (e.g., a liquid containing a capillary material 41). The container 4 has an open proximal end 42. A heater 30 is arranged to cover the open proximal end of the container 4. In some embodiments, the heater 30 is a fluid-permeable heater having a substantially flat profile. In one embodiment, the heater 30 is a substantially flat grid structure of electrically heated wires. The wires or other heating elements of the heater 30 may or may not be in direct physical contact with the aerosol-forming substrate 41. A mouthpiece 1 having a substantially tubular elongated body 15 is aligned with the main housing, the container 4, and the heater 30. The elongated body 15 has an open distal end facing the heater 30.

[0039] Figure 1The embodiment shown in FIG includes a first channel 10 that defines a first flow path in the mouthpiece 1. Incoming ambient air 20 enters the first flow path via an inlet 100 and follows the flow path defined by the first channel 10. This flow path causes the ambient air to impinge on the center of the heater 30. Preferably, the impingement occurs at the geometric center of the heater and at an angle of ninety degrees or near ninety degrees (i.e., the flow is substantially normal to the plane containing the heating surface of the heater 30). The vaporized liquid produced by the heater 30 is entrained as an aerosol by the airflow 20, and from there the air is delivered to the outlet 12 at the proximal or mouth end of the mouthpiece 1 to be inhaled when the user draws a puff. In some embodiments, a single channel such as the first channel 10 alone is sufficient to draw in the desired amount of ambient air during each puff. In other embodiments, it may be desirable to include two or more inlets and connected channels. For example, a second channel (not shown) may be provided to draw in additional air so that the ambient air flows merge before impinging on the heater 30.

[0040] exist Figure 1 In the embodiment of the present invention, the inlet 100 to the first flow path is an opening or bore in the mouthpiece 1 located in the distal half of the elongated body 15 of the mouthpiece 1. The first flow path in the upstream second channel portion 101 extends in the elongated body parallel to the outer circumference of the elongated body to the proximal end of the mouthpiece. In the radially inwardly directed portion 102 of the first channel 10, the first airflow 20 is directed to the center of the elongated body, and in the centrally arranged portion 103 of the first channel, the first airflow 20 is directed to the heater 30 to impinge on the center 31 of the heater 30. The first airflow 20 passes through the heater 30 and diffuses radially outward to several longitudinal end portions 104 of the first channel 10. The longitudinal end portions 104 are regularly arranged along the outer circumference within the elongated body.

[0041] In this embodiment, the flow path and corresponding channels are arranged entirely within the mouthpiece 1 of the aerosol generating system. One or more other flow paths may be defined in the mouthpiece, for example by symmetrically arranged channels, so that the airflows merge when the ambient air reaches the centrally arranged portion 103.

[0042] Figure 2, in which a heater 30 is disposed at the bottom of the cartridge, covering the open distal end 43 of the container 41. In this embodiment, a first inlet 100A is disposed in the main housing 5 and directs ambient air 20A directly toward the center of the main housing in a radially inwardly directed portion 102A of a first channel. Additionally, a second inlet 100B is disposed in the main housing 5 and directs ambient air 20B directly toward the center of the main housing 5 in a radially inwardly directed second channel 102B. The first and second channels merge to form a single airflow within a centrally disposed portion 103 of the first channel, and the combined airflow is directed to perpendicularly impinge upon the heater 30. The air then passes through the heater 30, entraining aerosol generated by the heating of the liquid in the aerosol-forming substrate 41 by the heater 30. Before being directed toward the proximal end of the cartridge 4, the aerosol-containing air enters a ninety-degree bend into one of several elongated longitudinal portions 105 of the first channel 10, disposed along the cartridge 4 between the cartridge 4 and the inner surface of the main housing 5.

[0043] There, the aerosol-containing airflow is directed toward and away from a single centrally located opening 52 in the main housing 5. A mouthpiece (not shown) may be positioned adjacent to and aligned with the main housing. Preferably, the mouthpiece then also has a centrally located opening and an end portion 104 of the first channel 10 to receive the aerosol-containing airflow and direct it toward a single outlet opening 12 in the proximal end of the mouthpiece 1.

[0044] Figure 3A and 3B An additional embodiment of system 8 is depicted, comprising a cartridge 4 with a heater 30 disposed at the bottom of the cartridge, covering the open distal end 43 of cartridge housing 41. In this embodiment, a first inlet 100A is disposed in main housing 5 and directs ambient air 20A directly toward the center of the main housing in a radially inwardly directed portion 102A of a first channel. Additionally, a second inlet 100B is disposed in main housing 5 and directs ambient air 20B directly toward the center of the main housing 5 in a radially inwardly directed second channel 102B. The first and second channels merge to form a single airflow within a centrally disposed portion 103 of the first channel, and the combined airflow is directed to vertically impinge upon heater 30. Conductive contacts 60, electrically coupled to a power source (not shown) located within main housing 5, electrically contact corresponding contacts of heater 30 and supply current to the heater.

[0045] Air arriving via the first channel portion 103 passes through the heater 30 and entrains vapor and condensed droplets produced by heating the liquid in the aerosol-forming substrate 41 by the heater 30. The aerosol thus produced enters the ninety-degree bends 45a, 45b into one of several elongated longitudinal portions 105 of the first channel 10, which are arranged between and along the barrel 4, before being directed toward the proximal end of the barrel 4. Thereafter, the aerosol is directed toward and away from the centrally located outlet opening 12 in the proximal end of the mouthpiece 1.

[0046] Figure 3B Through decomposition to show system 8 in more detail.As can be seen, the cartridge housing 4 comprising sections 4A and 4B accommodates the liquid containing high retention material or high release material (HRM) 41, and said cartridge housing serves as a liquid reservoir and directs liquid to heater 30 to evaporate at the heater. Capillary tube disc 44 (for example fiber disc) is arranged between HRM 41 and heater 30. The material of capillary tube disc 44 may be more heat-resistant than HRM 41, because it approaches heater 30 so that insulation is provided and protection HRM itself is not decomposed. Capillary tube disc 44 keeps moist because of the aerosol formation liquid of HRM, to ensure that when starting the heater, the liquid for vaporization is provided.

[0047] Figure 4 The data shown in Figure 3 show the relationship between air flow rate and cooling of the grid heater. Cooling rates were measured using different grid heaters: Reking (45 microns / 180 inches), Haver (25 microns / 200 inches), and 3 Warrington (25 microns / 250 inches). The measured data for the Reking heater is indicated by a cross, the measured data for the Haver heater is indicated by a circle, and the measured data for the 3 Warrington heaters is indicated by a triangle. All heaters were operated at three watts. Temperatures were measured using thermocouples connected to the heaters. An increase in the flow rate, indicated in liters / minute [L / min] on the x-axis, resulted in a lower measured temperature on the grid heater. The typical size of the airflow in an aerosol generating system can be roughly estimated by a standard smoking protocol (e.g., Health Canada smoking protocol), which effectively cools the heater. For example, Health Canada's exemplary smoking protocol involves inhaling 55 ml of a mixture of air and steam in 2 seconds. An alternative is 55 ml in 3 seconds. None of the exemplary smoking protocols accurately mimics behavior, but in fact serves as a representative of what an average user would inhale. To compensate for the higher cooling rates associated with the high velocity of airflow and the vertical impingement of air on the surface of heater 30, it may be necessary to supply increased levels of current to its heating elements.

[0048] Figure 5The graph of FIG shows the average temperature at the heater versus time during a puff. Curve 60 represents reference temperature data for the heater, where the total airflow is directed to the heater. For the reference data, the heater was heated using 5 watts.

[0049] Figure 6 The effect of directing a vapor-entrained airflow along the portion of the cartridge housing 4 containing the liquid storage portion 41 on the temperature of the aerosol-laden airflow at the mouthpiece outlet during a single puff is shown. The data refers to an example where ambient airflow was introduced via an outlet in the main housing such that it perpendicularly impinged on the surface of a substantially planar heater disposed in a transverse plane across the distal end of the cartridge opening at the inhalation end of the mouthpiece and curved around a downstream flow path to carry the airflow toward the inhalation end of the mouthpiece, as shown. Figure 2 and Figure 3A The temperature curve 61 represents the outlet air temperature of the heater powered at 5 watts, where the total airflow is based on Figure 1 The arrangement shown in FIG impinges on the heater and leaves. Temperature curve 71 shows the outlet air temperature of the heater also powered at 5 watts, but where the air flow is delivered close to the liquid storage portion to promote cooling, as shown in FIG. Figure 2 and Figure 3A Because the heat is transferred to the cartridge housing area close to the liquid storage portion, Figure 2 and Figure 3A The temperature of the aerosol-laden airflow at the proximal outlet of the arrangement main housing 5 and mouthpiece 1 is significantly lower. Typically, the 'fresh' air that is mixed into the aerosol-laden airflow is at room temperature.

[0050] Significant differences can also be seen in the ratio of the vapor pressure at the mouthpiece outlet to the saturation pressure of the glycerol solution (Pvapor / Psaturation) during one puff. This ratio is shown in Figure 7 Curve 72 refers to the pressure data at the outlet of the heater powered by 5 watts, where Figure 2 3A directs the total airflow to the heater. Curve 62 refers to the pressure data at the outlet of the heater powered by 5 watts, where the total airflow is calculated based on Figure 1 The arrangement impinges on the heater. This indicates a greater degree of supersaturation of the glycerol solution, which favors aerosolization of smaller droplets. The simulation clearly predicts smaller droplet sizes for the cooler vapor of the separated airflow embodiment compared to the vapor of the non-separated or total airflow embodiments. These simulation data 67 for a single puff at the mouthpiece outlet are shown in Figure 8 The Y axis represents the droplet diameter ratio of the separated airflow to the total airflow system. During one puff on the aerosol generating system, the ratio is calculated and displayed as d_separation / d_reference = T*Ln(S)reference / T*Ln(S)separation (relative to time in seconds), where T is the temperature in absolute degrees and S is the value obtained as a function of Pv and The saturation ratio of the function.

[0051] FIG9 a is a diagram of a first heater 30. The heater 30 is a fluid-permeable component of the heating element and includes a mesh 36 formed from 304L stainless steel, wherein the mesh size is approximately 400 Mesh US (approximately 400 filaments per inch). The filaments have a diameter of approximately 16 microns. The mesh is connected to electrical contacts 32, which are separated from each other by gaps 33 and formed from copper or tin foil having a thickness of approximately 30 microns. The electrical contacts 32 are disposed on a polyimide substrate 34 having a thickness of approximately 120 microns. The filaments forming the mesh define the spaces between the filaments. The gaps in this example have a width of approximately 37 microns, but larger or smaller gaps can be used. Using these roughly sized meshes allows the meniscus of the aerosol-forming substrate to form in the gaps and allows the mesh of the heating element to draw the aerosol-forming substrate through capillary action. The open area of ​​the mesh, i.e., the ratio of the area of ​​the gaps to the total area of ​​the mesh, is advantageously between 25% and 56%. The total resistance of the heating element is approximately 1 ohm. The mesh provides the vast majority of this resistance so that the mesh generates most of the heat. In this example, the mesh has a resistance that is more than 100 times higher than the electrical contacts 32.

[0052] The substrate 34 is electrically insulating and, in this example, is formed from a polyimide sheet approximately 120 microns thick. The substrate is circular and has a diameter of 8 mm. The grid is rectangular and has side lengths of 5 mm and 2 mm. These dimensions allow for the manufacture of a complete system similar in size and shape to a conventional cigarette or cigar. Another example of dimensions that have been found to be effective is a circular substrate with a diameter of 5 mm and a rectangular grid of 1 mm x 4 mm.

[0053] FIG9 b is a diagram of an alternative heater assembly. In the heating element of FIG9 b , a conductive heat-generating filament 37 is directly bonded to a substrate 34, and contacts 32 are subsequently bonded to the filament. As previously described, contacts 32 are separated from each other by insulating gaps 33 and are formed from copper foil approximately 30 microns thick. The same structure of substrate, filament, and contacts can be used for a grid-type heater as shown in FIG9 a. Using the contacts as the outermost layer can be beneficial in providing reliable electrical contact with a power source.

[0054] Back to Figures 1 to 3B , the capillary material 41 is advantageously oriented in the housing 4 to deliver liquid to the heater 30. When the cartridge is assembled, the heater filaments 36, 37, 38 may come into contact with the capillary material 41 and may deliver the aerosol-forming substrate directly to the mesh heater.

[0055] In use, the heating element operates by resistive heating. Current is passed through the filaments 36, 37, 38 under the control of control electronics (not shown), heating the filaments to a desired temperature range. The mesh or array of filaments has a significantly higher resistance than the electrical contacts 32, 35 and electrical connectors (not shown) so that high temperatures are localized to the filaments. The system can be configured to generate heat in response to a user's puff by supplying current to the heating element, or it can be configured to generate heat continuously when the device is in the "on" state.

[0056] Different filament materials can be used for different systems. For example, in a continuous heating system, graphite filament is suitable because it has a relatively low specific heat capacity and is compatible with low-current heating. In a suction-driven system that uses high-current pulses to generate heat in a short period of time, stainless steel filament with a high specific heat capacity may be more suitable.

[0057] In such Figures 1 to 3B In the above described barrel system, except for Figure 1 In addition to the cartridge housing described in the foregoing, the cartridge housing 4 can also be a separate cartridge container. In particular, the cartridge containing the liquid is a prefabricated product that can be inserted into a cartridge housing that is provided in the aerosol generating system for accommodating prefabricated cartridges.

Claims

1. An aerosol generating system comprising: a liquid storage portion comprising a container for containing a liquid aerosol-forming substrate and defining an opening; a heater assembly, wherein the heater assembly extends across the opening along a transverse plane and includes at least one heating element that is electrically operated; as well as a first channel defining a first flow path, wherein a portion of the first channel is arranged relative to the transverse plane so that at least a portion of the first channel directs an impingement of air originating from outside the aerosol generating system and across a surface portion of the at least one heating element, wherein the portion of the first channel that directs the impingement of air and across the surface portion of the at least one heating element is orthogonal to the transverse plane, wherein an aerosol is generated at a distal end of a cartridge housing containing an aerosol-forming substrate, wherein the heater assembly is disposed at the distal end of the container.

2. An aerosol generating system according to claim 1, wherein the aerosol generating system comprises a main unit and a cartridge removably coupled to the main unit, wherein the liquid storage portion and the heater assembly are provided in the cartridge, and the main unit comprises a power source.

3. An aerosol generating system according to claim 1 or 2, further comprising a mouthpiece, wherein the opening of the container faces away from the mouthpiece.

4. An aerosol generating system according to claim 1 or 2, further comprising a cartridge, a cartridge housing and a mouthpiece, wherein the open end of the cartridge housing is arranged facing away from the mouthpiece, and wherein the heating element is arranged at a distal end of the housing.

5. An aerosol generating system according to claim 1 or 2, wherein a portion of the first channel is sized and arranged to convey air along a curved portion away from the heater assembly.

6. An aerosol generating system according to claim 1 or 2, further comprising a capillary material in contact with or adjacent to the heating element, the capillary material being used to transport the aerosol-forming substrate to the heating element.

7. An aerosol generating system according to claim 6, wherein the capillary material comprises a ceramic material.

8. An aerosol generating system according to claim 6, wherein the first airflow channel defines an airflow path extending in a direction normal to the plane and the surface of the capillary material.

9. An aerosol generating system according to claim 1 or 2, wherein the heater assembly is a fluid permeable heater assembly comprising one or more electrically conductive heating elements.

10. An aerosol generating system according to claim 9, wherein the fluid permeable heater assembly comprises one or more heating elements located in a common plane so that the heater assembly has a substantially flat orientation.

11. An aerosol generating system according to claim 9, wherein the fluid permeable heater assembly comprises a pattern of conductive filaments printed on a heat-resistant carrier, wherein the carrier is ceramic.

12. An aerosol generating system according to claim 1 or 2, wherein the portion of the first channel is arranged relative to the transverse plane so that at least a portion of the first channel guides air originating from outside the aerosol generating system to impinge on a central portion of the at least one heating element and across a surface portion of the at least one heating element to provide an airflow on the heating element in a radially outward direction.

13. An aerosol generating system according to claim 1 or 2, wherein the heating element partially or fully covers the opening.

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