WO2023070270A1

WO2023070270A1 - Aerosol-generating device having a restricted airflow pathway

Info

Publication number: WO2023070270A1
Application number: PCT/CN2021/126131
Authority: WO
Inventors: Enrico TURRINI; Jerome Uthurry
Original assignee: Philip Morris Products S.A.
Priority date: 2021-10-25
Filing date: 2021-10-25
Publication date: 2023-05-04

Abstract

An aerosol-generating device (100) comprising: an air inlet (116); a cavity for receiving at least part of an aerosol-generating article; and an airflow channel (118) defining an airflow pathway extending between the air inlet and the cavity; wherein the airflow channel comprises a first airflow channel portion (118a) and a second airflow channel portion (118b), the cross-sectional area of the airflow pathway in the first airflow channel portion being less than the cross-sectional area of the airflow pathway in the second airflow channel portion such that the aerosol-generating device is configured to restrict the airflow in first airflow channel portion.

Description

AEROSOL-GENERATING DEVICE HAVING A RESTRICTED AIRFLOW PATHWAY

The present disclosure relates to an aerosol-generating device. In particular, but not exclusively, the present disclosure relates to a handheld electrically operated aerosol-generating device for heating an aerosol-forming substrate to generate an aerosol and for delivering the aerosol to a consumer. The present disclosure also relates to an aerosol-generating system comprising an aerosol-generating device and an aerosol-generating article.

Aerosol generating devices which heat an aerosol-forming substrate to produce an aerosol without burning the aerosol-forming substrate are known in the art and are often referred to as heat-not-burn devices. The aerosol-forming substrate is typically provided within an aerosol-generating article, together with other components such as filters. The aerosol-generating article may have a rod shape for insertion of the aerosol-generating article into a cavity of the aerosol-generating device. A heating element is typically arranged in or around the cavity for heating the aerosol-forming substrate once the aerosol-generating article is inserted into the cavity of the aerosol-generating device. In use, the heating element heats the aerosol-generating article inserted into the cavity of the aerosol-generating device to generate an aerosol from the aerosol-forming substrate. In many such devices, the consumer draws the aerosol from an end of the aerosol-generating article which protrudes from the aerosol-generating device.

For consumers, the “resistance to draw” (RTD) is a key quality parameter of an aerosol-generating article and is a measure of the pressure drop through the aerosol-generating article. In other words, it is a measure of how much suction force a consumer has to exert to draw air and generated aerosol through the aerosol-generating article. In aerosol-generating articles for heat-not-burn devices, it is desirable to seek to replicate the RTD to draw of a conventional cigarette. An acceptable RTD for consumer comfort for a conventional cigarette is typically in the range of 60 to 100 millimetres of water gauge (mmWg) .

There are several ways to customise the RTD of an aerosol-generating article. For example, RTD can be adjusted by varying the density or size of tobacco components within a tobacco plug. Alternatively or additionally, elements can be provided at the proximal or distal end of a consumable which restrict the airflow and so produce a pressure drop. Like for example, a filter. Furthermore, the RTD parameter tolerances for various components of the aerosol-generating article are significant, particularly for a rod made from a natural product like a tobacco rod that is made of finely cut and only slightly compressed tobacco leaves. For example, the RTD variation for a tobacco plug having a length of 10mm can vary from 10 mmWg to 25 mmWg. This variation has an impact on the performance of the aerosol-generating article and the aerosol delivered to a consumer. Moreover, once a component of the aerosol-generating article such a filter plug or tobacco plug has been produced, there is little possibility to further adjust the RTD. Therefore, a consumer may need to provide a different suction force for different aerosol-generating articles which may adversely affect the consumer’s experience.

As used herein, the terms “ ‘distal” , “upstream” “proximal” and “downstream” describe the relative positions of components, or portions of components, of an aerosol-generating device and aerosol generating article. Aerosol generating articles and devices according to the present disclosure have a proximal end through which, in use, an aerosol exits the article or device for delivery to a consumer, and have an opposing distal end. In use, a consumer draws on the proximal end of the aerosol generating article. The terms upstream and downstream are relative to the direction of aerosol or air movement through the aerosol generating article or aerosol-generating device when a consumer draws on the proximal end of the aerosol-generating article. The proximal end of the aerosol-generating article is downstream of the distal end of the aerosol-generating article. The proximal end of the aerosol-generating article may also be referred to as the downstream end of the aerosol-generating article and the distal end of the aerosol-generating article may also be referred to as the upstream end of the aerosol-generating article.

It would be desirable to provide an aerosol-generating device which is less dependent on the characteristics of the aerosol-generating article to provide a satisfactory and consistent consumer experience. In particular, it would be desirable to provide an aerosol-generating device which provides a more stable and repeatable RTD.

According to an example of the present disclosure, there is provided an aerosol-generating device. The aerosol-generating device may comprise an air inlet. The aerosol-generating device may comprise a cavity for receiving an aerosol-generating article. The aerosol-generating device may comprise an airflow channel defining an airflow pathway extending between the air inlet and the cavity. The airflow channel may comprises a first airflow channel portion and a second airflow channel portion. The cross-sectional area of the airflow pathway in the first airflow channel portion may be less than the cross-sectional area of the airflow pathway in the second airflow channel portion. The aerosol-generating device may be configured to restrict the airflow in first airflow channel portion.

According to an example of the present disclosure, there is provided an aerosol-generating device comprising an air inlet, a cavity for receiving an aerosol-generating article and an airflow channel defining an airflow pathway extending between the air inlet and the cavity. The airflow channel comprises a first airflow channel portion and a second airflow channel portion. The cross-sectional area of the airflow pathway in the first airflow channel portion is less than the cross-sectional area of the airflow pathway in the second airflow channel portion such that the aerosol-generating device is configured to restrict the airflow in first airflow channel portion.

Advantageously, in the above-described example, a significant amount of RTD is generated in the aerosol-generating device and not solely in the aerosol-generating article. This means that the aerosol-generating device is less dependent on the characteristics of the aerosol-generating article to provide the necessary RTD. The RTD is generated by providing a first airflow channel portion having an airflow pathway of reduced cross-sectional area compared to remainder of the airflow channel. The reduced cross-sectional area restricts the airflow. Since the dimensions of the airflow channel of the aerosol-generating device are fixed and are the same for every use, the RTD value is comparatively constant. Therefore, substantially the same suction force from a consumer is required for each puff during a consumer experience. Furthermore, the RTD is repeatable and stable over the lifespan of the aerosol-generating device and also during the use of a single aerosol-generating article.

A resistance to draw through the airflow channel may be greater than 50 millimetres of water gauge. A resistance to draw through the airflow channel is between 20 millimetres of water gauge and 100 millimetres of water gauge. A resistance to draw through the airflow channel may be between 25 millimetres of water gauge and 95 millimetres of water gauge. A resistance to draw through the airflow channel may be between 30 millimetres of water gauge and 90 millimetres of water gauge. A resistance to draw through the airflow channel may be between 35 millimetres of water gauge and 85 millimetres of water gauge. A resistance to draw through the airflow channel may be between 40 millimetres of water gauge and 80 millimetres of water gauge. A resistance to draw through the airflow channel may be between 45 millimetres of water gauge and 75 millimetres of water gauge. A resistance to draw through the airflow channel may be between 50 millimetres of water gauge and 70 millimetres of water gauge.

Unless otherwise specified, the resistance to draw (RTD) of the aerosol-generating device or an aerosol-generating article or a component of either is measured in accordance with ISO 6565-2015. The RTD refers to the pressure required to force air through the full length of a component. The terms “pressure drop” or “draw resistance” of a component or article may also refer to the “resistance to draw” . Such terms generally refer to the measurements in accordance with ISO 6565-2015 are normally carried out at under test at a volumetric flow rate of about 17.5 millilitres per second at the output or downstream end of the measured component at a temperature of about 22 degrees Celsius, a pressure of about 101 kPa (about 760 Torr) and a relative humidity of about 60%.

An end of the first airflow channel portion may be arranged at the air inlet to restrict the airflow pathway at the air inlet.

A ratio of the cross-sectional area of the airflow pathway in the second airflow channel portion to the cross-sectional area of the airflow pathway in the first airflow channel portion may be between 10: 1 and 100: 1, and preferably between 10: 1 and 20: 1. These ratios have been found to be particularly effective at providing a desirable RTD.

The airflow channel may comprise a tubular casing. An internal surface of the tubular casing may define the airflow pathway.

The first airflow channel portion of the tubular casing may have an internal width or diameter of between 0.5 millimetres and 2 millimetres, and preferably between 0.75 millimetres and 1.5 millimetres. These dimensions have been found to be particularly effective at providing a desirable RTD.

The second airflow channel portion of the tubular casing may have an internal width or diameter of between 4 millimetres and 6 millimetres.

A ratio of the length of the second airflow channel portion to the length of the first airflow channel portion may be between 5: 1 and 1: 1, and preferably between 4: 1 and 2: 1. These ratios have been found to be particularly effective at providing a desirable RTD.

The first airflow channel portion has a length of between 5 millimetres and 25 millimetres, preferably between 12 millimetres and 18 millimetres, more preferably between 14 millimetres and 16 millimetres, and yet more preferably about 15 millimetres. These dimensions have been found to be particularly effective at providing a desirable RTD.

The first airflow channel portion may be tapered. The first airflow channel portion may have an exit width or diameter (at a downstream end of the first airflow channel portion) that is smaller than an entry width or diameter (at a upstream end of the first airflow channel portion) . The exit width or diameter of the first airflow channel portion may be between 5 percent and 15 percent smaller than the entry width of the first airflow channel portion, or preferably about 10 percent smaller. The width or diameter of the first airflow channel portion may decrease linearly between the upstream and downstream ends of the first airflow channel portion. The width or diameter of the first airflow channel portion may decrease non-linearly between the upstream and downstream ends of the first airflow channel portion.

The first airflow channel portion may have an entry width or diameter of between 1 millimetre and 2 millimetres, preferably between 1 millimetre and 1.5 millimetres and more preferably about 1.3 millimetres. The first airflow channel portion may have an exit width or diameter of between 0.75 millimetres and 1.5 millimetres, preferably between 1 millimetre and 1.25 millimetres and more preferably about 1.2 millimetres.

The first airflow channel portion may have an exit width or diameter (at a downstream end of the first airflow channel portion) that is larger than an entry width or diameter (at a upstream end of the first airflow channel portion) . The exit width or diameter of the first airflow channel portion may be between 5 percent and 15 percent larger than the entry width of the first airflow channel portion, or preferably about 10 percent larger. The width or diameter of the first airflow channel portion may increase linearly between the upstream and downstream ends of the first airflow channel portion. The width or diameter of the first airflow channel portion may increase non-linearly between the upstream and downstream ends of the first airflow channel portion.

The first airflow channel portion may have an exit width or diameter of between 1 millimetre and 2 millimetres, preferably between 1 millimetre and 1.5 millimetres and more preferably about 1.3 millimetres. The first airflow channel portion may have an entry width or diameter of between 0.75 millimetres and 1.5 millimetres, preferably between 1 millimetre and 1.25 millimetres and more preferably about 1.2 millimetres.

The first and second airflow channel portions may be integrally formed in the tubular casing. This helps to reduce component count and simplify manufacture of the aerosol-generating device.

The first airflow channel portion may comprise a removable plug. The removable plug may be configured to be connected to the second airflow channel portion. The removable plug may have a through-bore extending between its opposing ends to define an airflow pathway through the plug. Advantageously, in this arrangement, the removable plug provides the RTD. Different removable plugs having through-bores of different cross-sectional areas may be used to enable a consumer to configure the aerosol-generating device to have a preferred RTD. The removable plug may have an RTD of about 20 millimetres of water gauge, or about 30 millimetres of water gauge, or about 40 millimetres of water gauge, or about 50 millimetres of water gauge, or about 60 millimetres of water gauge.

The aerosol-generating device may further comprise a heater for heating the aerosol-generating article in the cavity.

The heater may comprise one or more electric heating elements. The electric heating elements may comprise an electrically resistive material. Suitable electrically resistive materials include but are not limited to: semiconductors such as doped ceramics, electrically “conductive” ceramics (such as, for example, molybdenum disilicide) , carbon, graphite, metals, metal alloys and composite materials made of a ceramic material and a metallic material. Such composite materials may comprise doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum and metals from the platinum group. Examples of suitable metal alloys include stainless steel, nickel-, cobalt-, chromium-, aluminium-titanium-zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, gold-and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, Timetal ^TM, Kanthal ^TM and other iron-chromium-aluminium alloys, and iron-manganese-aluminium based alloys. In composite materials, the electrically resistive material may optionally be embedded in, encapsulated or coated with an insulating material or vice-versa, depending on the kinetics of energy transfer and the external physicochemical properties required. Alternatively, the electric heaters may comprise one or more infra-red heating elements, photonic sources, or inductive heating elements.

The one or more heating elements may be formed using a metal or metal alloy having a defined relationship between temperature and resistivity. Heating elements formed in this manner may be used to both heat and monitor the temperature of the heating element during operation.

The heating element may be deposited in or on a rigid carrier material or substrate. The heating element may be formed as a track on a suitable insulating material, such as ceramic or glass. The heating element may be sandwiched between two insulating materials.

The heater may comprise an internal heater or an external heater, or both internal and external heaters, where “internal” and “external” refer to a position relative to the aerosol-forming substrate.

The internal heater may take any suitable form. For example, the internal heater may take the form of a heating blade. Alternatively, the internal heater may take the form of a casing or substrate having different electro-conductive portions, or an electrically resistive metallic tube. Alternatively, the internal heater may be one or more heating needles or rods that run through the centre of the aerosol-forming substrate. Other alternatives include a heating wire or filament, for example a Ni-Cr (Nickel-Chromium) , platinum, gold, silver, tungsten or alloy wire or a heating plate.

The external heater may take any suitable form. For example, the external heater may take the form of one or more flexible heating foils on a dielectric substrate, such as polyimide. The flexible heating foils can be shaped to conform to the perimeter of the cavity for receiving the aerosol-generating article. Alternatively, the external heater may take the form of a heating coil, a metallic grid or grids, a flexible printed circuit board, a moulded interconnect device (MID) , ceramic heater, flexible carbon fibre heater or may be formed using a coating technique, such as plasma vapour deposition, on a suitable shaped substrate.

The heater may be a tubular heater which is arranged to receive an aerosol-forming substrate or aerosol-generating article within an internal space of the tube. The tubular heater may comprise a tubular support or substrate having a heating element disposed on or within the support or substrate. The heating element may be disposed on an inside surface of the tube or an outside surface of the tube. In one embodiment, the heater may comprise an aluminium oxide ceramic tube with a Kanthal ^TM heating element circumscribing the external cylindrical surface of the tube.

The aerosol-generating device may further comprise a power supply or source for supplying power to the internal and external heaters. The power supply may be any suitable power supply, for example a DC voltage source. In one embodiment, the power supply is a Lithium-ion battery. Alternatively, the power supply may be a Nickel-metal hydride battery, a Nickel cadmium battery, or a Lithium based battery, for example a Lithium-Cobalt, a Lithium-Iron-Phosphate or a Lithium-Polymer battery.

The aerosol-generating device is preferably a handheld aerosol-generating device that is comfortable for a consumer to hold between the fingers of a single hand.

The aerosol-generating device may further comprise control circuitry configured to control a supply of electrical power to the heater assembly. The control circuitry may comprise a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, or an application specific integrated chip (ASIC) or other electronic circuitry capable of providing control. The control circuitry may comprise further electronic components. For example, in some embodiments, the control circuitry may comprise any of: sensors, switches, display elements. Power may be supplied to the heater assembly continuously following activation of the device or may be supplied intermittently, such as on a puff-by-puff basis. The power may be supplied to the heater assembly in the form of pulses of electrical current, for example, by means of pulse width modulation (PWM) .

The aerosol-generating device may comprise a housing. The housing may comprise the cavity for receiving an aerosol-forming substrate or aerosol-generating article. The housing may comprise the heater, power supply and control circuitry. The housing may comprise an air inlet. The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics or composite materials containing one or more of those materials, or thermoplastics that are suitable for food or pharmaceutical applications, for example polypropylene, polyetheretherketone (PEEK) and polyethylene. The material is preferably light and non-brittle.

According to another example of the present disclosure, there is provided an aerosol-generating system comprising any of the above-described aerosol-generating devices. The aerosol-generating system may comprise an aerosol-generating article. The aerosol-generating article may comprise an aerosol-forming substrate.

According to an example of the present disclosure, there is provided an aerosol-generating system comprising any of the above-described aerosol-generating devices and an aerosol-generating article. The aerosol-generating article comprises an aerosol-forming substrate.

As used herein, the term “aerosol-generating article” refers to an article comprising an aerosol-forming substrate that, when heated in an aerosol-generating device, releases volatile compounds that can form an aerosol. An aerosol-generating article is separate from and configured for combination with an aerosol-generating device for heating the aerosol-generating article.

The aerosol-generating article may be substantially cylindrical in shape. The aerosol-generating article may be substantially elongate. The aerosol-forming substrate may be substantially cylindrical in shape. The aerosol-forming substrate may be substantially elongate.

The aerosol-generating article may have a total length between approximately 30 mm and approximately 100 mm. The aerosol-generating article may have an external diameter between approximately 5 mm and approximately 12 mm. The aerosol-forming substrate may have a length of between approximately 10 mm and approximately 18 mm. Further, the diameter of the aerosol-forming substrate may be between approximately 5 mm and approximately 12 mm. The aerosol-generating article may comprise a filter plug. The filter plug may be located at the downstream end of the aerosol-generating article. The filter plug may be a cellulose acetate filter plug. The filter plug is approximately 7 mm in length in one embodiment, but may have a length of between approximately 5 mm to approximately 12 mm.

In one embodiment, the aerosol-generating article may have a total length of approximately 45 mm. The aerosol-generating article may have an external diameter of approximately 7.3 mm but may have an external diameter of between approximately 7.0 mm and approximately 7.4 mm. Further, the aerosol-forming substrate may have a length of approximately 12 mm. Alternatively, the aerosol-forming substrate may have a length of approximately 16 mm. The aerosol-generating article may comprise an outer paper wrapper. Further, the aerosol-generating article may comprise a separation between the aerosol-forming substrate and the filter plug. The separation may be approximately 21 mm or approximately 26 mm, but may be in the range of approximately 5 mm to approximately 28 mm. The separation may be provided by a hollow tube. The hollow tube may be a made from cardboard or cellulose acetate.

The aerosol-forming substrate may be a solid aerosol-forming substrate. Alternatively, the aerosol-forming substrate may comprise both solid and liquid components. The aerosol-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavour compounds which are released from the substrate upon heating. Alternatively, the aerosol-forming substrate may comprise a non-tobacco material. The aerosol-forming substrate may further comprise an aerosol former. Examples of suitable aerosol formers are glycerine and propylene glycol.

If the aerosol-forming substrate is a solid aerosol-forming substrate, the solid aerosol-forming substrate may comprise, for example, one or more of: powder, granules, pellets, shreds, spaghettis, strips or sheets containing one or more of: herb leaf, tobacco leaf, fragments of tobacco ribs, reconstituted tobacco, homogenised tobacco, extruded tobacco and expanded tobacco. The solid aerosol-forming substrate may be in loose form, or may be provided in a suitable container or cartridge. Optionally, the solid aerosol-forming substrate may contain additional tobacco or non-tobacco volatile flavour compounds, to be released upon heating of the substrate. The solid aerosol-forming substrate may also contain capsules that, for example, include the additional tobacco or non-tobacco volatile flavour compounds and such capsules may melt during heating of the solid aerosol-forming substrate.

As used herein, homogenised tobacco refers to material formed by agglomerating particulate tobacco. Homogenised tobacco may be in the form of a sheet. Homogenised tobacco material may have an aerosol-former content of greater than 5 percent on a dry weight basis. Homogenised tobacco material may alternatively have an aerosol former content of between 5 percent and 30 percent by weight on a dry weight basis. Sheets of homogenised tobacco material may be formed by agglomerating particulate tobacco obtained by grinding or otherwise comminuting one or both of tobacco leaf lamina and tobacco leaf stems. Alternatively, or in addition, sheets of homogenised tobacco material may comprise one or more of tobacco dust, tobacco fines and other particulate tobacco by-products formed during, for example, the treating, handling and shipping of tobacco. Sheets of homogenised tobacco material may comprise one or more intrinsic binders, that is tobacco endogenous binders, one or more extrinsic binders, that is tobacco exogenous binders, or a combination thereof to help agglomerate the particulate tobacco; alternatively, or in addition, sheets of homogenised tobacco material may comprise other additives including, but not limited to, tobacco and non-tobacco fibres, aerosol-formers, humectants, plasticisers, flavourants, fillers, aqueous and non-aqueous solvents and combinations thereof.

In a particularly preferred embodiment, the aerosol-forming substrate comprises a gathered crimpled sheet of homogenised tobacco material. As used herein, the term ‘crimped sheet’ denotes a sheet having a plurality of substantially parallel ridges or corrugations. Preferably, when the aerosol-generating article has been assembled, the substantially parallel ridges or corrugations extend along or parallel to the longitudinal axis of the aerosol-generating article. This advantageously facilitates gathering of the crimped sheet of homogenised tobacco material to form the aerosol-forming substrate. However, it will be appreciated that crimped sheets of homogenised tobacco material for inclusion in the aerosol-generating article may alternatively or in addition have a plurality of substantially parallel ridges or corrugations that are disposed at an acute or obtuse angle to the longitudinal axis of the aerosol-generating article when the aerosol-generating article has been assembled. In certain embodiments, the aerosol-forming substrate may comprise a gathered sheet of homogenised tobacco material that is substantially evenly textured over substantially its entire surface. For example, the aerosol-forming substrate may comprise a gathered crimped sheet of homogenised tobacco material comprising a plurality of substantially parallel ridges or corrugations that are substantially evenly spaced-apart across the width of the sheet.

Optionally, the solid aerosol-forming substrate may be provided on or embedded in a thermally stable carrier. The carrier may take the form of powder, granules, pellets, shreds, spaghettis, strips or sheets. Alternatively, the carrier may be a tubular carrier having a thin layer of the solid substrate deposited on its inner surface, or on its outer surface, or on both its inner and outer surfaces. Such a tubular carrier may be formed of, for example, a paper, or paper like material, a non-woven carbon fibre mat, a low mass open mesh metallic screen, or a perforated metallic foil or any other thermally stable polymer matrix.

The solid aerosol-forming substrate may be deposited on the surface of the carrier in the form of, for example, a sheet, foam, gel or slurry. The solid aerosol-forming substrate may be deposited on the entire surface of the carrier, or alternatively, may be deposited in a pattern in order to provide a non-uniform flavour delivery during use.

Although reference is made to solid aerosol-forming substrates above, it will be clear to one of ordinary skill in the art that other forms of aerosol-forming substrate may be used with other embodiments. For example, the aerosol-forming substrate may be a liquid aerosol-forming substrate. If a liquid aerosol-forming substrate is provided, the aerosol-generating device preferably comprises means for retaining the liquid. For example, the liquid aerosol-forming substrate may be retained in a container or a liquid storage portion. Alternatively or in addition, the liquid aerosol-forming substrate may be absorbed into a porous carrier material. The porous carrier material may be made from any suitable absorbent plug or body, for example, a foamed metal or plastics material, polypropylene, terylene, nylon fibres or ceramic. The liquid aerosol-forming substrate may be retained in the porous carrier material prior to use of the aerosol-generating device or alternatively, the liquid aerosol-forming substrate material may be released into the porous carrier material during, or immediately prior to use. For example, the liquid aerosol-forming substrate may be provided in a capsule. The shell of the capsule preferably melts upon heating and releases the liquid aerosol-forming substrate into the porous carrier material. The capsule may optionally contain a solid in combination with the liquid.

Alternatively, the carrier may be a non-woven fabric or fibre bundle into which tobacco components have been incorporated. The non-woven fabric or fibre bundle may comprise, for example, carbon fibres, natural cellulose fibres, or cellulose derivative fibres.

Examples will now be further described with reference to the figures in which:

Figure 1 is a schematic cross-sectional view showing the interior of an aerosol-generating device according to an example of the present disclosure and an aerosol-generating article received within the aerosol-generating device.

Figure 2A is a schematic cross-sectional view showing the interior of an aerosol-generating device according to another example of the present disclosure and an aerosol-generating article received within the aerosol-generating device.

Figure 2B is an enlarged view of part of the aerosol-generating device of Figure 2A outlined by dashed box A.

Figure 3A is a schematic cross-sectional view showing the interior of an aerosol-generating device according to another example of the present disclosure and an aerosol-generating article received within the aerosol-generating device.

Figure 3B is an enlarged view of part of the aerosol-generating device of Figure 3A outlined by dashed box B.

Figure 4A is a schematic cross-sectional view of an aerosol-generating article for use with an aerosol-generating device of the present disclosure.

Figure 4B is a schematic cross-sectional view of another aerosol-generating article for use with an aerosol-generating device of the present disclosure.

Referring to Figure 1, this shows a schematic cross-sectional view of the interior of an aerosol-generating device 100 and an aerosol-generating article 200 received within the aerosol-generating device 100. Together, the aerosol-generating device 100 and aerosol-generating article 200 form an aerosol-generating system. In Figure 6, the aerosol-generating device 100 and aerosol-generating article are shown in a simplified manner. In particular, the elements of the aerosol-generating device 100 and aerosol-generating article 200 are not drawn to scale. Furthermore, elements that are not relevant for the understanding of the aerosol-generating device 100 have been omitted.

The aerosol-generating device 100 comprises a housing 102, a power supply 104, control circuitry 106, a heater casing 108, a heating chamber 110 and a tubular casing 112. The heating chamber 110 defines a cavity for receiving the aerosol-generating article 200 and has a flexible heating element (not shown) arranged around it for heating the heating chamber 110 and, in turn, the aerosol-generating article 200. The heater casing 108 surrounds the heating chamber 110 and prevents aerosol generated within the heating chamber 110 from leaking into the aerosol-generating device 100. The heater casing 108 may also comprise insulation (not shown) to reduce heat loss from the heating chamber 110 to the housing 102. The power supply 104 comprises a battery and, in this example, it is a rechargeable lithium ion battery. The control circuitry 106 is connected to both the power supply 104 and the heating element and controls the supply of electrical energy from the power supply 104 to the heating element to regulate the temperature of the heating element.

The aerosol-generating device 100 comprises an opening 114 formed in the housing 102 at a proximal or mouth end of the aerosol-generating device 100 through which an aerosol-generating article 200 can be inserted into the heating chamber 110. The aerosol-generating article 200 is longer than the cavity defined in part by the heating chamber 110 inside the aerosol-generating device and therefore a proximal or mouth end of the aerosol-generating article 200 protrudes from the aerosol-generating device 100 when the aerosol-generating article 200 is fully inserted.

The aerosol-generating article 200 comprises an aerosol-forming substrate 202 which is arranged in the aerosol-generating article such that, when the aerosol-generating article is fully inserted into the aerosol-generating device, the aerosol-forming substrate 202 is located within the heating chamber 110. The aerosol-generating article 200 may also comprise further components arranged along the length of the aerosol-generating article 200 as will be described in more detail below with reference to Figures 4A and 4B.

The aerosol-generating device 100 further comprises an air inlet 116 formed in the housing 102 at a distal end of the aerosol-generating device 100. The tubular casing 112 has a hollow interior and provides an airflow channel 118 defining an airflow pathway that extends between the air inlet 116 and the heating chamber 110. The airflow channel 118 provides fluid communication between the external atmosphere at the air inlet 116 and the aerosol-generating article 200 located in the heating chamber 110. The tubular casing 112 has a flange 120 which connects to the heater casing 108 to provide an airtight seal between the tubular casing 112 and the heater casing 108.

The airflow channel 118 comprises a first airflow channel portion 118a and a second airflow channel portion 118b. The first airflow channel portion 118a has an internal diameter d of 1 millimetre and the second airflow channel portion 118b has an internal diameter D of 4.2 millimetres. Therefore, the internal cross-sectional area of the first airflow channel portion 118a is over sixteen times smaller than the internal cross-sectional area of the second airflow channel portion 118b. The smaller internal cross-sectional area of the first airflow channel portion 118 creates a restriction of the airflow pathway in the first airflow channel portion 118a.

The first airflow channel portion 118a extends in a downstream direction from the air inlet 116 for a length of 15 millimetres, where it meets the increased diameter D of the second airflow channel portion 118b. This arrangement restricts the airflow at the air inlet 116. The inventors have observed that a restriction of 1 millimetre in diameter and 15 millimetres in length generates an RTD of 60 millimetres of water gauge. However, it will be appreciated that these dimensions can be varied to achieve different RTDs.

The aerosol-generating device 100 therefore generates an RTD which is similar to that of a conventional cigarette. This means that the aerosol-generating device 100 is less dependent on the characteristics of the aerosol-generating article 200 to provide the necessary RTD because a significant amount of the RTD is generated by the aerosol-generating device 100. Furthermore, since a significant amount of the RTD is being generated by the aerosol-generating device 100, the dimensions and structure of which are fixed, the RTD value is comparatively constant and repeatable. In addition, the aerosol-generating article 200 can be configured such that is has a significantly lower RTD than the aerosol-generating device 100 so that the majority of the RTD is being generated by the aerosol-generating device 100. This also means that the aerosol-generating article 200 does not significantly increase the RTD when it is used with the aerosol-generating device 100.

In use, a consumer inserts the aerosol-generating article 200 into the aerosol-generating device 100 via opening 114 which locates the aerosol-forming substrate 202 within the heating chamber 110. The consumer then activates the aerosol-generating device 100 which causes the control circuity 106 to supply power from the power supply 104 to the heating element arranged around the heating chamber 110 to controllably heat the aerosol-forming substrate 202 located within the heating chamber 110. This causes volatile compounds within the aerosol-forming substrate 202 to be released and form an aerosol. The consumer draws aerosol from the end of the aerosol-generating article 200 which protrudes from the aerosol-generating device 200. By applying a suction force with their mouth to the aerosol-generating article 200, the consumer creates a pressure drop within the aerosol-generating article 200, which is in fluid communication with the air inlet 116 of the aerosol-generating device 100 via the airflow channel 118. The pressure drop causes air to be drawn into the aerosol-generating device 100 via the air inlet 116 and flow via the airflow channel 118 to the aerosol-generating article 200. The air passes through the aerosol-generating article 200 entraining the aerosol, which is then delivered to the consumer.

Figure 2A shows a schematic cross-sectional view of the interior of another aerosol-generating device 300 in which an aerosol-generating article 200 has been received. The structure of the aerosol-generating device 300 and aerosol-generating article 200 of Figure 2A are the same as those in Figure 1 with the exception that the first airflow channel portion 318a of the airflow channel 318 is tapered. Figure 2B is an enlarged view of the part of the aerosol-generating device 300 of Figure 2A outlined by dashed box A, which shows the first airflow channel portion 318a in more detail. The taper of the first airflow channel portion 318a has been exaggerated in Figures 2A and 2B to illustrate the feature more clearly.

Similar to the aerosol-generating device 100 of Figure 1, the first airflow channel portion 318a and second airflow channel portion 318b of the aerosol-generating device 300 in Figures 2A and 2B are formed in the tubular casing 312. The first airflow channel portion 318a has an exit diameter d1 at a downstream end of the first airflow channel portion 318a that is smaller than an entry diameter d2 at a upstream end of the first airflow channel portion 318a. The first airflow channel portion 318a has an exit diameter d1 of 1.20 millimetres and an entry diameter d2 of 1.32 millimetres. Therefore, the exit diameter d1 is approximately 9 to 10 percent smaller than the entry diameter d2. Both the exit diameter d1 and entry diameter d2 are smaller than the diameter D of 4.2 millimetres of the second airflow channel portion 318b. Therefore the smaller internal cross-sectional area of the first airflow channel portion 318a creates a restriction of the airflow pathway in the first airflow channel portion 318a. The diameter of the first airflow channel portion 318a decreases linearly between the upstream and downstream ends of the first airflow channel portion 318a.

The first airflow channel portion 318a extends in a downstream direction from the air inlet 316 for a length of 15 millimetres, where it meets the increased diameter D of the second airflow channel portion 318b. This arrangement restricts the airflow at the air inlet 316. The arrangement of Figure 2B has been found to provide an effective RTD for the aerosol-generating device 300. However, it will be appreciated that the dimensions can be varied to achieve different RTDs.

Figure 3A shows a schematic cross-sectional view of the interior of another aerosol-generating device 400 in which an aerosol-generating article 200 has been received. The structure of the aerosol-generating device 400 and aerosol-generating article 200 of Figure 3A are the same as those in Figure 1 with the exception that the first airflow channel portion 418a of the airflow channel 418 comprises a removable plug 420. Figure 3B is an enlarged view of the part of the aerosol-generating device 400 of Figure 3A outlined by dashed box B, which shows the removable plug 420 in more detail.

Similar to the aerosol-generating device 100 of Figure 1, the second airflow channel portion 418b of the aerosol-generating device 400 in Figures 3A and 3B is formed in the tubular casing 412. As mentioned above, the first airflow channel portion 418a comprises a removable plug 420. The removable plug 420 has a through-bore 422 extending between its opposing ends to define an airflow pathway through the removable plug 420. The through-bore 422 formed in the removable plug 420 has an internal diameter d of 1 millimetre. The second airflow channel portion 418b formed in the tubular casing 412 has an internal diameter D of 4.2 millimetres. Therefore the smaller internal cross-sectional area of the through-bore 422 creates a restriction of the airflow pathway in the first airflow channel portion 318a formed by the removable plug 420.

The removable plug 420 has a narrower insertion portion 424 which is configured to be inserted into a distal end of the tubular casing 412 to connect the through-bore 422 to the second airflow channel portion 418b. The removable plug 420 is held in place in the tubular casing by an interference fit between the tubular casing 412 and the insertion portion 424. The removable plug 420 has a length of 15 millimetres. A distal end of the through-bore 422 forms an air inlet 416 and therefore the narrower through-bore 422 restricts the airflow at the air inlet 416. The arrangement of Figure 3B has been found to provide an effective RTD for the aerosol-generating device 400. However, it will be appreciated that the dimensions can be varied to achieve different RTDs. Indeed, different removable plugs having through-bores of different cross-sectional areas may be used to enable a consumer to configure the aerosol-generating device to have a preferred RTD.

Figure 4A shows a schematic cross-sectional view of an aerosol-generating article 500 for use with any of the aforementioned aerosol-generating devices. The aerosol-generating article 500 comprises an end plug 504, an aerosol-forming substrate 502, a hollow tube 506, a mouthpiece filter 508. Each of the aforementioned components of the aerosol-generating article 500 is a substantially cylindrical element, each having substantially the same diameter. The components are arranged sequentially in abutting coaxial alignment and are circumscribed by an outer paper wrapper 510 to form a cylindrical rod. The aerosol-forming substrate 502 is a tobacco rod or plug comprising a gathered sheet of crimped homogenised tobacco material circumscribed by a wrapper (not shown) . The crimped sheet of homogenised tobacco material comprises glycerine as an aerosol-former. The end plug 504 and mouthpiece filter 508 are formed from cellulose acetate fibres.

Figure 4B shows a schematic cross-sectional view of another aerosol-generating article 600 for use with any of the aforementioned aerosol-generating devices. The aerosol-generating article 600 comprises a tobacco rod 601 and a downstream section 605 arranged downstream of the tobacco rod. The tobacco rod 601 comprises an aerosol-forming substrate 602 wrapped in a plug wrap 603. The aerosol-forming substrate 602 comprises tobacco cut filler impregnated with about 12 percent by weight of an aerosol former, such as glycerine. The tobacco cut filler comprises 90 percent by weight of tobacco leaf lamina. The cut width of the tobacco cut filler is about 0.7 millimetres. The aerosol-forming substrate 12 comprises about 130 milligrams of tobacco cut filler.

The downstream section 605 comprises a hollow tubular element 606 located immediately downstream of the tobacco rod 601 of aerosol-generating substrate. The hollow tubular element 606 is in longitudinal alignment with the tobacco rod 601 and is combined with the tobacco rod 601 by means of an outer wrapper 607. In the embodiment of Figure 4B, the upstream end of the hollow tubular element 606 abuts the downstream end of the tobacco rod 601.

The hollow tubular element 606 comprises a hollow cylindrical tube made of cellulose acetate or of stiff paper, such as paper having a grammage (basis weight) of at least about 90 grams per square metre. The hollow tubular element 606 defines an internal cavity 608 that extends all the way from an upstream end of the hollow tubular element 606 to a downstream end of the hollow tubular element 606. The internal cavity 608 is substantially empty, and so substantially unrestricted airflow is enabled through the internal cavity 608.

The tobacco rod 1 has an RTD of approximately 18 millimetres of water gauge. The hollow tubular element 606 has a negligible RTD. Consequently, the hollow tubular element 606 does not substantially contribute to the overall RTD of the aerosol-generating article 10, which overall RTD is substantially the same as that of the tobacco rod 601. Accordingly, the aerosol-generating article 600 has an RTD which is significantly lower than the RTD of the aerosol-generating device so that the majority of the RTD is being generated by the aerosol-generating device. This also means that the aerosol-generating article 600 does not significantly increase the RTD when it is used with an aerosol-generating device.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about" . Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 5 percent of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic (s) of the claimed invention.

Claims

An aerosol-generating device comprising:

an air inlet;

a cavity for receiving at least part of an aerosol-generating article; and

an airflow channel defining an airflow pathway extending between the air inlet and the cavity;

wherein the airflow channel comprises a first airflow channel portion and a second airflow channel portion, the cross-sectional area of the airflow pathway in the first airflow channel portion being less than the cross-sectional area of the airflow pathway in the second airflow channel portion such that the aerosol-generating device is configured to restrict the airflow in first airflow channel portion.
An aerosol-generating device according to claim 1, wherein a resistance to draw through the airflow channel is greater than 50 millimetres of water gauge.
An aerosol-generating device according to claim 1, wherein a resistance to draw through the airflow channel is between 20 millimetres of water gauge and 100 millimetres of water gauge.
An aerosol-generating device according to claim 3, wherein a resistance to draw through the airflow channel is between 25 millimetres of water gauge and 95 millimetres of water gauge.
An aerosol-generating device according to claim 4, wherein a resistance to draw through the airflow channel is between 30 millimetres of water gauge and 90 millimetres of water gauge.
An aerosol-generating device according to claim 5, wherein a resistance to draw through the airflow channel is between 35 millimetres of water gauge and 85 millimetres of water gauge.
An aerosol-generating device according to claim 6, wherein a resistance to draw through the airflow channel is between 40 millimetres of water gauge and 80 millimetres of water gauge.
An aerosol-generating device according to claim 7, wherein a resistance to draw through the airflow channel is between 45 millimetres of water gauge and 75 millimetres of water gauge.
An aerosol-generating device according to claim 8, wherein a resistance to draw through the airflow channel is between 50 millimetres of water gauge and 70 millimetres of water gauge.
An aerosol-generating device according to any preceding claim, wherein an end of the first airflow channel portion is arranged at the air inlet to restrict the airflow pathway at the air inlet.
An aerosol-generating device according to any preceding claim, wherein a ratio of the cross-sectional area of the airflow pathway in the second airflow channel portion to the cross-sectional area of the airflow pathway in the first airflow channel portion is between 10: 1 and 100: 1.
An aerosol-generating device according to claim 11, wherein a ratio of the cross-sectional area of the airflow pathway in the second airflow channel portion to the cross-sectional area of the airflow pathway in the first airflow channel portion is between 10: 1 and 20: 1.
An aerosol-generating device according to any preceding claim, wherein the airflow channel comprises a tubular casing, an internal surface of the tubular casing defining the airflow pathway.
An aerosol-generating device according to claim 13, wherein the first airflow channel portion of the tubular casing has an internal width or diameter of between 0.5 millimetres and 2 millimetres.
An aerosol-generating device according to claim 14, wherein the first airflow channel portion of the tubular casing has an internal width or diameter of between 0.75 millimetres and 1.5 millimetres.
An aerosol-generating device according to any of claims 13 to 15, wherein the second airflow channel portion of the tubular casing has an internal width or diameter of between 4 millimetres and 6 millimetres.
An aerosol-generating device according to any preceding claim, wherein a ratio of the length of the second airflow channel portion to the length of the first airflow channel portion is between 5: 1 and 1: 1.
An aerosol-generating device according to claim 17, wherein a ratio of the length of the second airflow channel portion to the length of the first airflow channel portion is between 4: 1 and 2: 1.
An aerosol-generating device according to any preceding claim, wherein the first airflow channel portion has a length of between 5 millimetres and 25 millimetres.
An aerosol-generating device according to claim 19, wherein the first airflow channel portion has a length of between 12 millimetres and 18 millimetres
An aerosol-generating device according to claim 20, wherein the first airflow channel portion has a length of between 14 millimetres and 16 millimetres.
An aerosol-generating device according to claim 21, wherein the first airflow channel portion has a length of about 15 millimetres.
An aerosol-generating device according to any preceding claim, wherein the first airflow channel portion is tapered.
An aerosol-generating device according to claim 23, wherein the first airflow channel portion has an exit width or diameter at a downstream end of the first airflow channel portion that is smaller than an entry width or diameter at a upstream end of the first airflow channel portion.
An aerosol-generating device according to claim 24, wherein the exit width or diameter of the first airflow channel portion is between 5 percent and 15 percent smaller than the entry width of the first airflow channel portion.
An aerosol-generating device according to claim 25, wherein the exit width or diameter of the first airflow channel portion is about 10 percent smaller than the entry width of the first airflow channel portion.
An aerosol-generating device according to any of claims 23 to 26, wherein the width or diameter of the first airflow channel portion decreases linearly between the upstream and downstream ends of the first airflow channel portion.
An aerosol-generating device according to any of claims 23 to 26, wherein the width or diameter of the first airflow channel portion decreases non-linearly between the upstream and downstream ends of the first airflow channel portion.
An aerosol-generating device according to any of claims 23 to 28, wherein the first airflow channel portion has an entry width or diameter of between 1 millimetre and 2 millimetres.
An aerosol-generating device according to claim 29, wherein the first airflow channel portion has an entry width or diameter of between 1 millimetre and 1.5 millimetres.
An aerosol-generating device according to claim 30, wherein the first airflow channel portion has an entry width or diameter of about 1.3 millimetres.
An aerosol-generating device according to any of claims 23 to 31, wherein the first airflow channel portion has an exit width or diameter of between 0.75 millimetres and 1.5 millimetres.
An aerosol-generating device according to claim 32, wherein the first airflow channel portion has an exit width or diameter of between 1 millimetre and 1.25 millimetres.
An aerosol-generating device according to claim 33, wherein the first airflow channel portion has an exit width or diameter of about 1.2 millimetres.
An aerosol-generating device according to claim 23, wherein the first airflow channel portion has an exit width or diameter at a downstream end of the first airflow channel portion that is larger than an entry width or diameter at a upstream end of the first airflow channel portion.
An aerosol-generating device according to claim 35, wherein the exit width or diameter of the first airflow channel portion is between 5 percent and 15 percent larger than the entry width of the first airflow channel portion.
An aerosol-generating device according to claim 36, wherein the exit width or diameter of the first airflow channel portion is about 10 percent larger than the entry width of the first airflow channel portion.
An aerosol-generating device according to any of claims 35 to 37, wherein the width or diameter of the first airflow channel portion increases linearly between the upstream and downstream ends of the first airflow channel portion.
An aerosol-generating device according to any of claims 35 to 37, wherein the width or diameter of the first airflow channel portion increases non-linearly between the upstream and downstream ends of the first airflow channel portion.
An aerosol-generating device according to any of claims 35 to 39, wherein the first airflow channel portion has an exit width or diameter of between 1 millimetre and 2 millimetres
An aerosol-generating device according to claim 40, wherein the first airflow channel portion has an exit width or diameter of between 1 millimetre and 1.5 millimetres.
An aerosol-generating device according to claim 41, wherein the first airflow channel portion has an exit width or diameter of about 1.3 millimetres.
An aerosol-generating device according to any of claims 35 to 42, wherein the first airflow channel portion has an entry width or diameter of between 0.75 millimetres and 1.5 millimetres.
An aerosol-generating device according to claim 43, wherein the first airflow channel portion has an entry width or diameter of between 1 millimetre and 1.25 millimetres.
An aerosol-generating device according to claim 44, wherein the first airflow channel portion has an entry width or diameter of about 1.2 millimetres.
An aerosol-generating device according to any of claims 13 to 45, wherein the first and second airflow channel portions are integrally formed in the tubular casing.
An aerosol-generating device according to any of claims 13 to 45, wherein the first airflow channel portion comprises a removable plug configured to be connected to the second airflow channel portion, the plug having a through-bore extending between its opposing ends to define an airflow pathway through the plug.
An aerosol-generating device according to claim 47, wherein the removable plug has a resistance to draw of about 20 millimetres of water gauge.
An aerosol-generating device according to claim 47, wherein the removable plug has a resistance to draw of about 30 millimetres of water gauge.
An aerosol-generating device according to claim 47, wherein the removable plug has a resistance to draw of about 40 millimetres of water gauge.
An aerosol-generating device according to claim 47, wherein the removable plug has a resistance to draw of about 50 millimetres of water gauge.
An aerosol-generating device according to claim 47, wherein the removable plug has a resistance to draw of about 60 millimetres of water gauge.
An aerosol-generating device according to any preceding claim , further comprising a heater for heating the aerosol-generating article in the cavity.
An aerosol-generating system comprising an aerosol-generating device according to any of the preceding claims and an aerosol-generating article, the aerosol-generating article comprising an aerosol-forming substrate.
An aerosol-generating system according to claim 54, wherein the aerosol-generating article has a resistance to draw which is less than 50 percent of the resistance to draw of the airflow channel of the aerosol-generating device.
An aerosol-generating system according to claim 55, wherein the aerosol-generating article has a resistance to draw which is less than 40 percent of the resistance to draw of the airflow channel of the aerosol-generating device.
An aerosol-generating system according to claim 56, wherein the aerosol-generating article has a resistance to draw which is less than 30 percent of the resistance to draw of the airflow channel of the aerosol-generating device.
An aerosol-generating system according to any of claims 54 to 57, wherein the aerosol-generating article has a resistance to draw of less than 30 millimetres of water gauge.
An aerosol-generating system according to claim 58, wherein the aerosol-generating article has a resistance to draw of less than 25 millimetres of water gauge.
An aerosol-generating system according to claim 59, wherein the aerosol-generating article has a resistance to draw of less than 20 millimetres of water gauge.